History of the study of hyperventilation syndrome (HVS). The first clinical description of GVS belongs to Da Costa (1842), who summarized his observations of soldiers participating in the civil war. He observed respiratory disorders and various unpleasant sensations associated with them in the region of the heart, calling them "soldier's heart", "irritated heart". The connection of pathological symptoms with physical activity was emphasized, hence another term - "effort syndrome". In 1918, Lewis proposed another name - "neurocirculatory dystonia", which is still widely used by therapists. Such manifestations of HVS as paresthesia, dizziness, muscle spasms have been described; connection of increased breathing (hyperventilation) with muscular-tonic and tetanic disorders was noticed. As early as 1930, it was shown that pains in the region of the heart in Da Costa syndrome are not only associated with physical activity, but also with hyperventilation as a result of emotional disturbances. These observations were confirmed during the Second World War. Hyperventilation manifestations were noted both among soldiers and civilians, which indicated the importance of psychological factors in the genesis of HVS.

Etiology and pathogenesis. In the 80-90s of the 20th century, it was shown that GVS is part of the structure of the psychovegetative syndrome. The main etiological factor is anxiety, anxiety-depressive (rarely hysterical) disorders. It is mental disorders that disorganize normal breathing and lead to hyperventilation. The respiratory system, on the one hand, has a high degree of autonomy, on the other hand, a high degree of learning and a close connection with the emotional state, especially anxiety. These features of it underlie the fact that GVS is in most cases of psychogenic origin; extremely rarely it is caused by organic neurological and somatic diseases - cardiovascular, pulmonary and endocrine.

An important role in the pathogenesis of HVS is played by complex biochemical changes, especially in the system of calcium-magnesium homeostasis. Mineral imbalance leads to an imbalance in the system of respiratory enzymes, contributes to the development of hyperventilation.

The habit of incorrect breathing is formed under the influence of cultural factors, past life experiences, as well as stressful situations experienced by the patient in childhood. Peculiarity of children's psychogenic disorders in patients with HVS is that they often involve a violation of the respiratory function: children become witnesses of dramatic manifestations of asthma attacks, cardiovascular and other diseases. Patients themselves in the past often have an increased load on the respiratory system: running, swimming, playing wind instruments, etc. In 1991, I.V.

Thus, the pathogenesis of HVS appears to be multilevel and multidimensional. A psychogenic factor (most often anxiety) disrupts normal breathing, resulting in hyperventilation. An increase in pulmonary, alveolar ventilation leads to stable biochemical changes: excessive release of carbon dioxide (CO 2) from the body, the development of hypocapnia with a decrease in the partial pressure of CO 2 in the alveolar air and oxygen in arterial blood, as well as respiratory alkalosis. These shifts contribute to the formation of pathological symptoms: impaired consciousness, vegetative, muscular-tonic, algic, sensory and other disorders. As a result, there is an increase in mental disorders, a pathological circle is formed.

Clinical manifestations of HVS. GVS can be paroxysmal in nature (hyperventilation crisis), but more often hyperventilation disorders are permanent. GVS is characterized by the classic triad of symptoms: respiratory disturbances, emotional disturbances, and muscular-tonic disorders (neurogenic tetany).

The first are represented by the following types:

• "empty breath";
• violation of automatism of breathing;
• labored breathing;
• hyperventilation equivalents (sighs, coughs, yawns, sniffles).
• Emotional disorders are manifested by feelings of anxiety, fear, internal tension.

Muscular tonic disorders (neurogenic tetany) include:

• sensory disorders (numbness, tingling, burning);
• convulsive phenomena (muscle spasms, "obstetrician's hand", carpopedal spasms);
• Chvostek's syndrome II-III degree;
• positive Trousseau test.

In the first type of respiratory disorders - "empty breath" - the main sensation is dissatisfaction with the breath, a feeling of lack of air, which leads to deep breaths. Patients constantly lack air. They open vents, windows and become "air maniacs". Respiratory disorders are exacerbated in agoraphobic situations (metro) or sociophobic (exam, public speaking). Breathing in such patients is frequent and/or deep.

In the second type - a violation of the automatism of breathing - patients have a feeling of stopping breathing, so they continuously monitor the act of breathing and are constantly included in its regulation.

The third type - difficulty breathing syndrome - differs from the first variant in that breathing is felt by patients as difficult, performed with great effort. They complain of a "lump" in the throat, the obstruction of air into the lungs, tightness of breath. This variant is called "atypical asthma". Objectively marked increased breathing, irregular rhythm. In the act of breathing, the respiratory muscles are used. The patient's appearance is tense, restless. Examination of the lungs reveals no pathology.

The fourth type - hyperventilation equivalents - is characterized by periodically observed sighs, coughing, yawning, sniffling. These manifestations are sufficient to maintain prolonged hypocapnia and alkalosis in the blood.

Emotional disturbances in HVS are mainly of an anxious or phobic nature. The most common is generalized anxiety disorder. It, as a rule, is not associated with any specific stressful situation - the patient has been noted for a long time (more than 6 months) as various mental (feeling of constant internal tension, inability to relax, anxiety over trifles), and somatic manifestations. Among the latter, respiratory disorders (more often "empty breath" or hyperventilation equivalents - cough, yawning) can form the core of the clinical picture - along with, for example, algic and cardiovascular manifestations.

Respiratory disturbances reach a significant degree during a panic attack, when the so-called hyperventilation crisis develops. Disorders of the second and third types are more often noted - loss of automatism of breathing and shortness of breath. The patient has a fear of suffocation and other symptoms characteristic of a panic attack. To make a diagnosis of a panic attack, four of the following 13 symptoms must be observed: palpitations, sweating, chills, shortness of breath, choking, pain and discomfort in the left side of the chest, nausea, dizziness, feeling of derealization, fear of going crazy, fear of death, paresthesia, waves heat and cold. An effective method of stopping a hyperventilation crisis and other symptoms associated with impaired breathing is breathing into a paper or plastic bag. In this case, the patient breathes his own exhaled air with a high content of carbon dioxide, which leads to a decrease in respiratory alkalosis and the listed symptoms.

Agoraphobia is often the cause of DHW. This is the fear that arises in situations that the patient regards as difficult to help him. For example, a similar condition may occur in the subway, a store, etc. Such patients, as a rule, do not leave the house unaccompanied and avoid these places.

A special place in the clinical picture of HVS is occupied by an increase in neuromuscular excitability, manifested by tetany. Tetanic symptoms include:

• sensory disorders in the form of paresthesias (numbness, tingling, crawling "goosebumps", sensations of buzzing, burning, etc.);
• convulsive muscular-tonic phenomena - spasms, information, tonic convulsions in the hands, with the phenomenon of "obstetrician's hand" or carpopedal spasms.

These manifestations often occur in the picture of a hyperventilation crisis. In addition, the Khvostek symptom, a positive Trousseau cuff test and its variant, the Trousseau-Bahnsdorff test, are characteristic of an increase in neuromuscular excitability. Characteristic electromyographic (EMG) signs of latent muscle tetany are essential in the diagnosis of tetany. An increase in neuromuscular excitability is caused by the presence in patients with HVS of a mineral imbalance of calcium, magnesium, chlorides, potassium, caused by hypocapnic alkalosis. There is a clear relationship between increased neuromuscular excitability and hyperventilation.

Along with the classic manifestations of HVS, paroxysmal and permanent, there are other disorders that are characteristic of the psychovegetative syndrome in general:

• cardiovascular disorders - pain in the heart, palpitations, discomfort, chest tightness. Objectively noted lability of the pulse and blood pressure, extrasystole, ECG - fluctuation of the ST segment; acrocyanosis, distal hyperhidrosis, Raynaud's phenomenon;
• disorders of the gastrointestinal tract: increased intestinal motility, belching with air, bloating, nausea, abdominal pain;
• changes in consciousness, manifested by a feeling of unreality, lipothymia, dizziness, blurred vision, in the form of a fog or grid before the eyes;
• algic manifestations, represented by cephalgia or cardialgia.

So, for the diagnosis of DHW, it is necessary to confirm the following criteria:

1. The presence of polymorphic complaints: respiratory, emotional and musculo-tonic disorders, as well as additional symptoms.
2. Absence of organic nervous and somatic diseases.
3. Having a psychogenic history.
4. Positive hyperventilation test.
5. The disappearance of symptoms of a hyperventilation crisis when breathing into a bag or inhaling a mixture of gases (5% CO 2).
6. The presence of symptoms of tetany: Chvostek's symptom, a positive Trousseau test, a positive EMG test for latent tetany.
7. Change in blood pH towards alkalosis.

DHW treatment

The treatment of DHW is complex and is aimed at correcting mental disorders, teaching proper breathing, and eliminating mineral imbalance.

Non-drug methods

1. The essence of the disease is explained to the patient, they are convinced that it is curable (they explain the origin of the symptoms of the disease, especially somatic, their relationship with the mental state; they convince that there is no organic disease).
2. It is recommended to stop smoking, drink less coffee and alcohol.
3. Assign breathing exercises with the regulation of the depth and frequency of breathing. For its correct implementation, several principles must be observed. First, switch to diaphragmatic abdominal breathing, during which the “brake” Hering-Breuer reflex is activated, which causes a decrease in the activity of the reticular formation of the brain stem and, as a result, muscle and mental relaxation. Secondly, to maintain certain ratios between inhalation and exhalation: inhalation is 2 times shorter than exhalation. Thirdly, breathing should be rare. And finally, fourthly, breathing exercises should be carried out against the background of mental relaxation and positive emotions. Initially, breathing exercises continue for several minutes, then for quite a long time, forming a new psychophysiological pattern of breathing.
4. With severe hyperventilation disorders, breathing in a bag is recommended.
5. Autogenic training and respiratory-relaxation training are shown.
6. Psychotherapeutic treatment is highly effective.
7. Of the instrumental non-drug methods, biofeedback is used. The feedback mechanism with real-time objectification of a number of parameters allows achieving more effective mental and muscle relaxation, as well as more successfully than with autogenic training and respiratory-relaxation training, to regulate the breathing pattern. The biofeedback method has been successfully used for many years in the Headache and Autonomic Disorders Clinic named after A. acad. A. Wayne for the treatment of hyperventilation disorders, panic attacks, anxiety and anxiety-phobic disorders, as well as tension headaches.

Medicinal methods

Hyperventilation syndrome refers to psychovegetative syndromes. Its main etiological factor is anxiety, anxiety-depressive and phobic disorders. Priority in his treatment is psychotropic therapy. In the treatment of anxiety disorders, antidepressants are more effective than anxiolytics. Patients with anxiety disorders should be prescribed antidepressants with pronounced sedative or anxiolytic properties (amitriptyline, paroxetine, fluvoxamine, mirtazapine). The therapeutic dose of amitriptyline is 50-75 mg / day, to reduce side effects: lethargy, drowsiness, dry mouth, etc., the dose should be increased very slowly. Selective serotonin reuptake inhibitors are better tolerated and have less adverse side effects. The therapeutic dose of fluvoxamine is 50-100 mg/day, paroxetine is 20-40 mg/day. Nausea is one of their most common unwanted side effects. To prevent or more successfully overcome it, it is also recommended to prescribe the drug in half the dosage at the beginning of therapy and take it with meals. Given the hypnotic effect of fluvoxamine, the drug should be administered in the evening; paroxetine has less pronounced hypnogenic properties, so it is more often recommended to take it with breakfast. The four-cyclic antidepressant mirtazapine has a pronounced anti-anxiety and hypnotic effect. It is usually prescribed at bedtime, starting with 7.5 or 15 mg, gradually increasing the dose to 30-60 mg / day. When prescribing balanced antidepressants (without a pronounced sedative or activating effect): citalopram (20-40 mg / day), escitalopram (10-20 mg / day), sertraline (50-100 mg / day), etc., their combination is possible for a short period of 2-4 weeks with anxiolytics. The use of such a "benzodiazepine bridge" in some cases makes it possible to accelerate the onset of action of psychotropic therapy (this is important, given the delayed effect of antidepressants by 2-3 weeks) and overcome the increase in anxiety that temporarily occurs in some patients at the beginning of therapy. If the patient has hyperventilation crises during an attack, along with breathing into the bag, anxiolytics should be taken as abortive therapy: alprazolam, clonazepam, diazepam. The duration of psychotropic therapy is 3-6 months, if necessary, up to 1 year.

Psychotropic drugs, along with a positive therapeutic effect, have a number of negative properties: unwanted side effects, allergization, the development of addiction and dependence, especially to benzodiazepines. In this regard, it is advisable to use alternative agents, in particular, agents that correct mineral imbalance, which is the most important symptom-forming factor in hyperventilation disorders.

As a means of reducing neuromuscular excitability, prescribe drugs that regulate the exchange of calcium and magnesium. The most commonly used ergocalciferol (vitamin D 2), Calcium-D 3 , as well as other drugs containing calcium, for 1-2 months.

The generally accepted view is that magnesium is an ion with clear neurosedative and neuroprotective properties. Magnesium deficiency in some cases leads to increased neuro-reflex excitability, reduced attention, memory, convulsive seizures, impaired consciousness, heart rhythm, sleep disorders, tetany, paresthesia, ataxia. Stress - both physical and mental - increases the need for magnesium in the body and causes intracellular magnesium deficiency. The state of stress leads to the depletion of intracellular magnesium reserves and its loss in the urine, since an increased amount of adrenaline and norepinephrine promotes its release from cells. Magnesium sulfate has long been used in neurological practice as an antihypertensive and anticonvulsant. There are studies on the effectiveness of magnesium in the treatment of the consequences of acute cerebrovascular accident and traumatic brain injury, as an additional remedy for epilepsy, the treatment of autism in children.

Magne B 6 contains magnesium lactate and pyridoxine, which additionally potentiates the absorption of magnesium in the intestine and its transport into the cells. The implementation of the sedative, analgesic and anticonvulsant effects of magnesium-containing drugs is based on the property of magnesium to inhibit excitation processes in the cerebral cortex. The appointment of the drug Magne B 6, both in the form of monotherapy, 2 tablets 3 times a day, and in complex therapy in combination with psychotropic drugs and non-drug methods of treatment, leads to a decrease in the clinical manifestations of HVS.

For literature inquiries, please contact the editor.

E. G. Filatova, doctor of medical sciences, professor
MMA them. I. M. Sechenov, Moscow

Considering that it has been a decade without major revelations on the theoretical front, string theory guerrillas are now under increasing pressure to tie their ephemeral speculations to something concrete. All this time, one unchanging question hung over their fantastic beliefs: do these ideas really describe our Universe?

This legitimate question arises in connection with the audacious ideas presented here, any of which can cause a stupor in the average person. One such claim is that everywhere in our world, wherever we go, there is a higher dimensional space within reach, but so tiny that we will never see or feel it. Or that our world could be torn apart by a Big Crunch, or exploded in a fleeting jet of cosmic decompactification, during which the area we inhabit will immediately change from 4D to 10D. Or, more simply, that everything in the universe - all matter, all forces and even space itself - is the result of vibrations of tiny strings in ten dimensions. And here comes the second question, which also requires consideration: do we have any hope of verifying any of this - extra dimensions, strings, branes, etc.?

The challenge facing string theorists remains the same as it was when they first tried to recreate the Standard Model: can we bring this amazing theory into the real world, not only connect it to our world, but also predict something new, what have we not seen before?

There is currently a huge gulf between theory and observation: the smallest things we can observe with current technology are about sixteen orders of magnitude larger than the Planck scale, where strings and extra dimensions are supposed to live, and so far there is no reasonable way overcome this gap. The "brute force" approach, i.e. direct observation, is probably out of the question, as it requires extraordinary skill and some degree of luck, so that ideas will have to be tested indirectly. But this challenge must be met if string theorists are to win over the skeptics and also convince themselves that their ideas add something to science and are not just grandiose speculations on a very small scale.

So where do we start? Let's look through a telescope? Let's collide particles at relativistic speeds and "sift through diamond dust" in search of clues? The shortest answer is that we do not know which road, if any, leads to the truth. We still haven't found the one experiment that we can bet on and that is designed to solve our problems once and for all. In the meantime, we are trying to study all of the above and even more, considering any idea that can provide any physical evidence. Researchers are ready to do it right now, when string phenomenology wins new positions in theoretical physics.

It is logical to first look up at the heavens, as Newton did when creating his theory of gravity and as astrophysicists did to test Einstein's theory of gravity. A close inspection of the heavens might, for example, shed light on one of the latest and strangest ideas in string theory—the idea that our universe is literally inside a bubble, one of the countless bubbles that grace the cosmic landscape. Although this idea may not seem the most promising to you, since it is more contemplative than natural science, we will nevertheless continue our story from where we left off in the previous chapter. And our example shows how difficult it is to implement these ideas in an experiment.

When we discussed bubbles in Chapter Eleven, we did so in the context of decompactification—that is, a process extremely improbable to be observed, since the time it takes for the universe to unfold is of the order of e(10,120) years, and a process that makes no sense to expect, since we still would not be able to see the decompactization of the bubble until it literally hit us. And if he hit us, then "we" would no longer exist; or we would be unable to understand what kind of "lid" slammed us. But perhaps there are other bubbles outside of "our" bubble. In particular, many cosmologists believe that right now we are sitting in one of the bubbles that formed at the end of inflation, a fraction of a second after the Big Bang, when a tiny pocket of low-energy matter appeared amid the high-energy inflationary vacuum, and has since expanded to become that the universe we know. In addition, it is widely believed that inflation never completely ends, but once it starts, it continues with the formation of countless bubble universes that differ in vacuum energies and other physical characteristics.

Proponents of the obscure idea of ​​the bubble theory are hoping to see not our current bubble, but rather signs of another bubble filled with a completely different vacuum state that inflated in our bubble sometime in the past. We could accidentally find evidence of such an observation, for example, in the cosmic microwave background (CMB), that is, the cosmic microwave background that “washes” our Universe. The CMF, a consequence of the Big Bang, is quite homogeneous with an accuracy of 1:100,000. According to the logic of things, the CMF should also be isotropic, that is, having the same properties in all directions. A collision with another bubble, which will lead to the predominance of energy in one part of the universe in relation to the other, should break the observed uniformity and cause anisotropy. This would mean the existence of a preferred direction in our universe, a kind of “arrow” that would point directly to the center of another bubble just before it crashed into us. Despite the dangers associated with the decompactification of our own universe, a collision with another universe in a different bubble is not necessarily fatal. The wall of our bubble, believe it or not, is able to provide some protection. However, such a collision can leave a noticeable imprint in the CMB, which will not be just the result of random fluctuations.

A kind of calling card that cosmologists are looking for, perhaps, is the discovered anisotropy of the CMF, called by its discoverers Joao Mageijo and Keith Land from King's College London "the axis of evil." Mageijo and Land argue that the hot and cold patches in the CMF appear to be oriented along a specific axis; if the data was processed correctly, then this means that the universe has a certain orientation, which contradicts the sacred cosmological principles that say that all directions in the universe are indistinguishable. But at the moment, no one knows if the supposed axis is anything more than a statistical fluctuation.

If we could get reliable evidence that another bubble hit us, what would that prove? And will it have anything to do with string theory? “If we weren’t living in a bubble, there wouldn’t be a collision, so for starters we would know that we really live in a bubble,” explains physicist Matthew Kleban of New York University. Moreover, thanks to the collision, we would also know that there is at least one more bubble outside. “While this does not prove the truth of string theory, the theory makes many strange predictions, one of which is that we live in a bubble” - one of the many such bubbles scattered throughout the landscape of string theory. “At the very least,” Kleban says, “we could see something strange and unexpected, which is also a prediction of string theory.”

However, there is a very important nuance that Henry Tai of Cornell University points out: Bubble collisions can also occur in quantum field theory, which has nothing to do with string theory. Tai admits that in the event that traces of a collision are found, he does not know which theory is better to explain them as a consequence - string theory or field theory.

The question then becomes: can something like this ever be seen, regardless of its origin? The probability of finding a bubble, of course, depends on whether any random bubble is in our path or within the "light cone". "He could be anywhere," says Ben Freifogel, a physicist at the University of California. "It's a matter of probabilities, and we don't have enough knowledge to determine those probabilities." Although no one can accurately estimate the chance of such a discovery, most experts believe that it is extremely small.

Although calculations suggest that bubbles do not provide fertile ground for research, many physicists still believe that cosmology offers an excellent chance to test string theory, given that the near-Planck energies at which strings are created are so huge that they can never be reproduced. in laboratory conditions.

Perhaps the greatest hope of ever seeing strings, estimated to be on the order of 10 -33 cm, is the possibility that they formed at the time of the Big Bang and increase in size as the universe expands. I mean the hypothetical formations called cosmic strings, - this idea arose before string theory, but was revived with renewed vigor due to association with this theory.

According to the traditional view, which coincides with that of string theory, cosmic strings are thin, superdense filaments formed during a "phase transition" in the first microsecond of cosmic history. As a crack inevitably appears in ice when water freezes, so the Universe in the first moments of its life goes through a phase transition, which is accompanied by the appearance of various kinds of defects. The phase transition had to occur in different areas at the same time, and linear defects should have formed at the junction, that is, where these areas ran into each other, leaving behind thin threads of untransformed matter, forever trapped initial state.

The cosmic strings should emerge during this phase transition in the form of a spaghetti-like tangle, with individual filaments propagating at speeds close to the speed of light. They are long and curved, with complex curves, fragmented, closed into smaller loops that resemble tightly stretched rubber bands. It is believed that cosmic strings, whose thickness is much less than the size of subatomic particles, must be almost immeasurably thin and almost infinite in length and stretched due to cosmic expansion in order to cover the entire Universe.

These extended filaments are characterized by mass per unit length, or stress, which serves as a measure of gravitational bonding. Their linear density can reach a monstrously high value - about 10 22 grams per centimeter of length for strings with the energy parameters of the Grand Unified Theory. “Even if we compress one billion neutron stars down to the size of one electron, we will hardly achieve the mass-energy density characteristic of the strings of the Grand Unified Theory,” says astronomer Alejandro Ganjui from the University of Buenos Aires.

These strange objects became popular in the early 1980s with cosmologists, who saw them as potential "seeds" for the formation of galaxies. However, in 1985, Edward Witten argued in his paper that the presence of cosmic strings should have created inhomogeneities in the CMB that should be much larger than those observed, thus casting doubt on their existence.

Since that time, cosmic strings have attracted continued interest, largely due to their popularity in string theory, which has prompted many people to look at these objects in a new light. Cosmic strings are now considered a common by-product of inflationary models based on string theory. The most recent versions of the theory show that the so-called fundamental strings, the basic units of energy and matter in string theory, can reach astronomical sizes and do not suffer from the problems described by Witten in 1985. Tai and his colleagues explained how cosmic strings could form at the end of the inflationary stage and not disappear, scattering through the universe during a short period of unstoppable expansion, when the universe doubled its size, perhaps fifty or even a hundred times in a row.

Tai showed that these strings should be less massive than Witten strings and other strings that physicists discussed in the 1980s, and therefore their influence on the universe should not be as strong, as has already been proven by observations. Meanwhile, Joe Polchinski of the University of California at Santa Barbara has shown why newly formed strings could be stable on a cosmological time scale.

The efforts of Ty, Polchinski and others, cleverly addressing the objections that Witten raised two decades ago, have revived interest in cosmic strings. Due to the postulated density, cosmic strings should exert a noticeable gravitational influence on their surroundings and thus reveal themselves.

For example, if a string runs between our galaxy and another galaxy, then the light from that galaxy will bend around the string symmetrically, creating two identical images that are close to each other in the sky. “Typically, in gravitational lensing, you would expect to see three images,” explains Alexander Vilenkin, a cosmic string theorist at Tufts University. Some of the light will go straight through the lensing galaxy, and the rest of the rays will go around it on both sides. But light cannot pass through a string because the diameter of the string is much smaller than the wavelength of the light; thus strings, unlike galaxies, will only produce two images, not three.

Hope loomed in 2003 when a Russian-Italian team led by Mikhail Sazhin of Moscow State University announced that they had obtained a double image of the galaxy in the constellation Raven. The images were at the same distance, had the same redshift, and were spectrally identical up to 99,96 % . Either these were two extremely similar galaxies that happened to be side by side, or the first observation of a gravitational lens created by a cosmic string. In 2008, a more detailed analysis based on data from the Hubble Space Telescope, which gives a much clearer picture than the ground-based telescope used by Sazhin and colleagues, showed that what appeared to be a lensed galaxy was actually two different galaxies; thus the effect of the cosmic string was eliminated.

A similar approach, called microlensing, is based on the assumption that the loop formed by a broken cosmic string can create potentially detectable gravitational lenses near individual stars. Although it is not possible to instrumentally observe a forked star, one can try to look for a star that will periodically double its brightness while remaining unchanged in color and temperature, which may indicate the presence of a cosmic string loop oscillating in the foreground. Depending on location, speed, tension, and particular vibrational mode, the loop will double-image in some cases and not in others - the star's brightness may vary over seconds, hours, or months. Such evidence could be found by the Gaia Satellite Telescope, which is scheduled to launch in 2012 and is tasked with observing billions of stars in the galaxy and its immediate environs. A Large Synoptic Survey Telescope (LSST) is now being built in Chile, which can also capture a similar phenomenon. "Direct astronomical detection of superstring relics is part of the challenge of experimentally testing some of the basic assumptions of string theory," says Cornell astronomer David Chernoff, a member of the LSST collaborative project.

Meanwhile, researchers continue to look for other means of detecting cosmic strings. For example, theorists believe that cosmic strings could form kinks and kinks in addition to loops, emitting gravitational waves as these irregularities are ordered or destroyed.

Gravitational waves of a certain frequency can be detected using a space antenna using the principle of a laser interferometer (Laser Interferometer Space Antenna, LISA) and designed for an orbital observatory that is currently being developed for NASA.

The measurements will be carried out using three spacecraft located at the vertices of an equilateral triangle. The two sides of this triangle, 5 million kilometers long, will form the arms of the giant Michelson interferometer. When a gravitational wave distorts the structure of space-time between two spacecraft, it becomes possible to measure the relative changes in the length of the interferometer arms from the phase shift of the laser beam, despite the smallness of this effect. Vilenkin and Thibault Damour of the French Institute for Higher Scientific Research (IHES) have suggested that precise measurements of these waves could reveal the presence of cosmic strings. “The gravitational waves emitted by cosmic strings have a specific shape that is very different from the waves generated by collisions of black holes or waves emitted by other sources,” Tai explains. - The signal should start from zero and then quickly increase and then decrease just as quickly. By “waveform” we mean the nature of the increase and decrease in the signal, and the described character is inherent only in cosmic strings.

Another approach is based on looking for distortions in the CMF caused by strings. A 2008 study by Mark Hyndmarsh of the University of Sussex suggested that cosmic strings may be responsible for the lumpy distribution of matter seen with the Wilkinson Microwave Background Anisotropy Probe.

This lumping phenomenon is known as non-gaussianity. Although the data obtained by the Hindmarsh team suggest the presence of cosmic strings, many scientists were skeptical, considering the observed correlation as a mere coincidence. This issue needs to be clarified by performing more accurate measurements of the CMF. The study of the potentially non-Gaussian distribution of matter in the Universe is actually one of the main tasks of the Planck satellite launched by the European Space Agency in 2009.

“Cosmic strings may or may not exist,” says Vilenkin. But the search for these objects is in full swing, and if they exist, "their detection seems quite realistic in the next few decades."

In some models of string inflation, the exponential growth of the volume of space occurs in a region of the Calabi-Yau manifold called crooked neck. In the abstract field of string cosmology, warped throats are considered to be objects with fundamental and generic characteristics "that emerge naturally from six-dimensional Calabi-Yau space," says Princeton's Igor Klebanov. While this does not guarantee that there will be inflation in such areas, it is expected that the geometric framework of the twisted necks will help us understand inflation and solve other mysteries. For theorists, there are great opportunities here.

The throat, the most common defect in the Calabi-Yau space, is a cone-shaped spike, or conifold, that protrudes from the surface. Cornell University physicist Liam McAllister says the rest of space, often described as bulk space, can be thought of as a large scoop of ice cream sitting on top of a thin and infinitely pointed cone. This throat becomes wider when the fields laid down by string theory (technical name - streams) are turned on. Cornell University astronomer Rachel Veen argues that since a given Calabi-Yau space likely has more than one curved throat, a rubber glove would be a better analogy. “Our three-dimensional universe is like a dot moving down the finger of a glove,” she explains.

Inflation ends when the brane, or "point," reaches the tip of the finger where the antibrane or stack of antibranes is. Rachel Veen believes that since the motion of the brane is constrained by the shape of the finger or throat, "the geometry of the throat will determine the specific characteristics of inflation."

Regardless of the analogy chosen, different curved neck models will lead to different predictions. spectrum cosmic strings - a full set of strings of various tensions that can arise under conditions of inflation, which, in turn, will tell us what Calabi-Yau geometry underlies the universe. "If we're lucky enough to see [the full spectrum of cosmic strings]," says Polchinski, "then we'll be able to tell which picture of the crooked throat is correct and which isn't."

If we are unlucky enough not to find a single cosmic string or network of cosmic strings, then we can still restrict the choice of Calabi-Yau space shapes through cosmological observations that rule out some models of cosmic inflation while leaving others. At least, physicist Gary Shui of the University of Wisconsin and his colleagues are following this strategy. “How did extra dimensions twist in string theory? Shui asks. "We argue that accurate measurements of the cosmic microwave background radiation will give us a clue."

Shui suggests that the latest string theory-based models of cosmic inflation are approaching the point at which detailed predictions about our universe can be made. These predictions, which vary depending on the specific Calabi-Yau geometry triggering inflation, can now be tested by analyzing the CMF data.

The basic premise is that inflation is driven by brane motion. And what we call our universe is actually on a three-dimensional brane. In this scenario, the brane and its antipode, the antibrane, are slowly moving towards each other in extra dimensions. In a more precise version of the theory, the branes move in the region of the curved throat within these extra dimensions.

Due to the mutual attraction of the brane and antibrane, when they separate, a potential energy is created that drives inflation. The fleeting process in which our four-dimensional space-time expands exponentially continues until the brane and antibrane collide and then annihilate, releasing the energy of the Big Bang and creating indelible imprints on the CMB. “The fact that the branes were moving allows us to learn more about space than if they were just sitting in a corner,” Ty says. - Just like at a cocktail party: you are unlikely to make many acquaintances if you stand modestly in one corner. But if you keep moving, you will learn a lot of interesting things.”

Researchers like Tai are inspired by the fact that the data is getting accurate enough that we can say that one Calabi-Yau space does not contradict the experimental data, while the other does. Thus, cosmological measurements are also made in order to impose restrictions on the kind of Calabi-Yau space in which we can live. "You take inflationary models and you divide them into two groups, one part will match observations, the other won't," says physicist Cliff Burgess of the Perimeter Institute for Theoretical Physics. "The fact that we can now distinguish between inflationary patterns means that we can also distinguish between the geometric constructions that gave rise to these patterns."

Shui and his former graduate student Bret Underwood, now at McGill University, have taken a few more steps in that direction. In 2007, in an article in Physical Review Letters Shui and Underwood showed that two different geometries for hidden six dimensions, which are variations of Calabi-Yau conifolds with curved throats, can give different patterns of cosmic radiation distribution. Shui and Underwood chose to compare two neck models - Klebanov-Strassler and Randall-Sandrum - whose geometries are well understood, and then looked at how inflation under these different conditions would affect the CMF. In particular, they focused on standard CMB measurements, that is, temperature fluctuations in the early life of the universe. These fluctuations are approximately the same on small and large scales. The rate of change in the magnitude of fluctuations when moving from a small scale to a large one is called spectral index. Shui and Underwood found a difference of 1% between the spectral indices of the two models, indicating that the choice of geometry leads to a measurable effect.

While this may not seem significant, a 1% difference is considered significant in cosmology. The recently launched Planck observatory should be able to measure the spectral index, at least at this level. In other words, it may turn out that by means of the Planck apparatus it is possible to obtain data that the geometry of the Klebanov-Strassler throat corresponds to observations, but the Randall-Sandrum geometry does not, or vice versa. “From the top of the neck, both geometries look pretty much the same, and people tend to think you can use one instead of the other,” notes Underwood. “Shui and I have shown that details matter a lot.”

However, moving from a spectral index, which is just a number, to an extra-dimensional geometry is a giant step. This is the so-called inverse problem: if we have enough data on the CMB, then can we determine what the Calabi-Yau space is? Burgess doesn't think it's possible in "this life," or at least not in the dozen years he has left until retirement. McAllister is also skeptical. “It will be a big win if we can tell in the next decade if inflation is happening or not,” she says. "I don't think we'll get enough experimental data to concretize the full shape of the Calabi-Yau space, although we might know what kind of neck it has or what kind of brane it contains."

Shui is more optimistic. Even though the inverse problem is much more difficult, he admits, we still have to take our best shot. “If you can only measure the spectral index, then it's hard to say anything definite about the geometry of space. But you get a lot more information if you can identify something like non-Gaussian features from the KMF data.” He believes that a clear indication of non-Gaussianity (deviation from the Gaussian distribution) will impose "significantly more restrictions on the geometry. Instead of one number - the spectral index, we will have an entire function - a whole bunch of numbers interconnected. A high degree of non-Gaussianity, Shui adds, could indicate a particular version of brane-induced inflation, such as the Dirac-Born-Infeld (DBI) model, which occurs within a well-described throat geometry. "Depending on the accuracy of the experiment, such a discovery may actually bring clarity to the problem."

Physicist Sarah Shandera of Columbia University notes that string theory inflation, such as the DBI model, will be important to us, even if we find that string theory is not the ultimate theory of nature. “The point is that it predicts a kind of non-Gaussianity that cosmologists have never thought about before,” Shandera says. And any experiments, if you ask the right questions and know what to look for, make up a large part of the whole game.

Another clue regarding string theory inflation can be found by examining the gravitational waves emitted during the strong phase transition that caused the inflation. The longest of these primordial space ripple waves cannot be directly observed because their wavelength range now spans the entire visible universe. But they leave traces in the microwave background radiation. Despite the fact that, according to theorists, this signal is difficult to distinguish from the CMB temperature maps, gravitational waves should create a characteristic pattern on the CMB photon polarization maps.

In some inflationary models of string theory, gravitational wave fingerprints are detectable, in others they are not. Roughly speaking, if the brane moves a small distance on the Calabi-Yau during inflation, then there is no estimable effect of the gravitational wave. But if the brane travels a long way through the extra dimensions, "leaving small circles like grooves on a gramophone record, then the result of the gravitational influence must be significant," Tai says. If the motion of the brane is tightly constrained, he adds, “there is a special kind of compactification and a special kind of Calabi-Yau. By seeing this, you will know what the type of manifold should be.” The compactifications discussed here are manifolds whose moduli are stabilized, which implies, in particular, the presence of a curved geometry and a curved neck.

Establishing the shape of Calabi-Yau space, including the shape of its throat, will require precise measurements of the spectral index and detection of non-Gaussianity, gravitational waves, and cosmic strings. Shiu suggests patience. “While we have confidence in the Standard Model, this model did not come about all at once. It was born out of a series of experiments carried out over many years. Now we need to take a lot of measurements to see if extra dimensions really exist or if there really is string theory behind it all.”

The main goal of research is not only to probe the geometry of hidden dimensions, but also to test string theory in general. McAllister, by the way, believes that this approach may give us the best chance to test the theory. “Perhaps string theory will predict a finite class of models, none of which will match the observed properties of the early universe, in which case we could say that the observations ruled out string theory. Some of the models have already been dropped, which is encouraging because it means that the current data really does make a difference between the models."

She adds that while such a claim is not entirely new to physicists, it is new to string theory, which is subject to experimental verification. And McAllister goes on to say that currently, crooked-neck inflation is one of the best patterns we've created so far, "but realistically, crooked-neck inflation may not occur, even if the picture looks perfect."

Finally, Rachel Bean agrees that “crooked-neck inflation patterns may not provide the expected response. But these models are based on geometries derived from string theory, from which we can make detailed predictions that can then be tested. In other words, it's a good starting point to start with."

The good news is that there is more than one starting point to get started. While some researchers comb the night (or day) sky for signs of extra dimensions, others have their eyes fixed on the Large Hadron Collider. Finding hints of the existence of extra dimensions is not a priority task of the collider, but it is quite high on the list of its tasks.

The most logical starting point for string theorists is the search for supersymmetric partners of already known particles. Supersymmetry is of interest to many physicists, not just string theorists: supersymmetric partners, which have the smallest mass, and these can be neutralinos, gravitinos or sneutrinos, are extremely important in cosmology, since they are considered the main candidates for the role of dark matter. The speculated reason why we have not yet observed these particles, and while they remain invisible to us and therefore dark, is that they are more massive than ordinary particles. Currently, there are no colliders powerful enough to produce these heavier "superpartners", so there are high hopes for the Large Hadron Collider.

In string theory models developed by Kumrun Vafa of Harvard University and Jonathan Heckman of the Institute for Advanced Study, the gravitino - the hypothetical superpartner of the graviton (the particle responsible for gravity) - is the lightest superpartner. Unlike heavier superpartners, the gravitino must be absolutely stable, since there is nothing for it to decay into. The gravitino in the above model makes up most of the dark matter in the universe. Although the gravitino is too weak to be observed with the Large Hadron Collider, Vafa and Heckman believe that another theoretical supersymmetric particle is the tau-slepton ( stau), the superpartner of the so-called tau lepton, should be stable somewhere in the range from a second to an hour, and this is more than enough for the detectors of the collider to fix it.

The discovery of such particles would confirm an important aspect of string theory. As we have seen, Calabi-Yau manifolds have been carefully chosen by string theorists as a suitable geometry for extra dimensions, in part because of the supersymmetry automatically built into their internal structure.

It is no exaggeration to say that the discovery of signs of supersymmetry at the Large Hadron Collider will be encouraging news for defenders of string theory and Calabi-Yau objects. Burt Ovrut explains that the characteristics of supersymmetric particles themselves can tell us about hidden dimensions, “because the way the Calabi-Yau manifold is compactified affects the kind of supersymmetry and the level of supersymmetry you get. You can find compactifications that preserve supersymmetry or those that break it.”

The confirmation of supersymmetry does not in itself confirm string theory, but at least points in the same direction, indicating that part of the story that string theory tells is true. On the other hand, if we do not find supersymmetric particles, this will not mean the collapse of string theory. This may mean that we made a mistake in the calculations and the particles are beyond the reach of the collider. Vafa and Heckman, for example, allow for the possibility that the collider could produce semi-stable and electrically neutral particles instead of tau-sleptons, which cannot be detected directly. If the superpartners turn out to be slightly more massive than this collider can produce, then higher energies will be required to reveal them and, therefore, a long wait for a new instrument that will eventually replace the Large Hadron Collider.

There is a small chance that the Large Hadron Collider could find more direct and less dubious evidence for the extra dimensions predicted by string theory. In experiments already planned at this facility, researchers will look for particles with extra-dimensional signs where they come from, the so-called Kaluza-Klein particles. The essence of the idea is that oscillations in high-order dimensions can manifest themselves as particles in our four-dimensional world. We can see either the remnants of the decay of Kaluza-Klein particles or, perhaps, even signs of particles disappearing from our world along with energy and passing into more multidimensional regions.

Invisible motion in extra dimensions will impart momentum and kinetic energy to the particle, so Kaluza-Klein particles are expected to be heavier than their slow four-dimensional counterparts. An example is the Kaluza-Klein gravitons. They will look like ordinary gravitons, being gravitational carrier particles, only they will be heavier due to the additional momentum. One way to distinguish such gravitons from the vast sea of ​​other particles produced by the collider is to pay attention not only to the mass of the particle, but also to its spin. Fermions, like electrons, have a certain angular momentum, which we refer to as spin-1/2. Bosons, such as photons and gluons, have slightly more angular momentum, qualifying as spin-1. Any particles found to have spin-2 at the collider are likely Kaluza-Klein gravitons.

Such a discovery would be of great importance, as physicists would not only catch the first glimpse of the long-awaited particle, but would also gain conclusive evidence for the existence of the extra dimensions themselves. Finding the existence of at least one extra dimension is a startling discovery in itself, but Shui and his colleagues wanted to go further and get clues to the geometry of this extra space. In a 2008 paper written with Underwood, Devin Walker of the University of California at Berkeley, and Katerina Zurek of the University of Wisconsin, Shui and his team found that a small change in the shape of the extra dimensions causes huge—50% to 100%—changes, like in mass, and in the nature of the interaction of Kaluza-Klein gravitons. “When we changed the geometry just a little, the numbers changed dramatically,” Underwood notes.

While Shui et al.'s analysis is far from drawing conclusions about the shape of an interior space or refining Calabi-Yau geometry, it does offer some hope of using experimental data to "reduce the class of allowed shapes to a small range." “The secret of our success lies in the cross-correlation between different types of experiments in cosmology and high energy physics,” says Shiu.

The mass of particles recorded at the Large Hadron Collider will also give us hints about the size of the extra dimensions. The fact is that for particles this is a passage to a multidimensional region, and the smaller these regions, the heavier the particles will be. You may ask how much energy is needed to walk down the aisle. Probably not much. But what if the passage is not short, but very narrow? Then the passage through the tunnel will result in a struggle for every inch of the way, accompanied, no doubt, by curses and promises, and of course, more energy. That's roughly what's going on here, and technically speaking, it all comes down to the Heisenberg uncertainty principle, which says that the momentum of a particle is inversely proportional to the accuracy of measuring its location. In other words, if a wave or particle is trapped in a very, very tiny space, where its position is limited by very narrow boundaries, then it will have a huge momentum and a correspondingly large mass. Conversely, if the extra dimensions are huge, then the wave or particle will have more room to move and therefore have less momentum and be easier to detect.

However, there is a trap hidden here: the Large Hadron Collider will only detect things like Kaluza-Klein gravitons if these particles are many, many lighter than expected, which suggests that either the additional dimensions are extremely curved, or they must be much larger than the Planck scale traditionally accepted in string theory. For example, in the Randall-Sandrum warp model, space with extra dimensions is bounded by two branes, between which there is a folded space-time. On one brane - high-energy, gravity is strong; on the other brane - low energy, gravity is weak. Because of this arrangement, mass and energy change radically depending on the position of space in relation to these two branes. This means that the mass of elementary particles, which we usually considered within the Planck scale (of the order of 10 28 electron volts), will have to be “rescaled” to a closer range, that is, up to 10 12 electron volts, or 1 tera electron volt, which already corresponds to the range of energies with which the collider operates.

The size of extra dimensions in this model may be smaller than in conventional string theory models (although such a requirement is not made), while the particles themselves must probably be much lighter and therefore have less energy than expected.

Another pioneering approach considered today was first proposed in 1998 by physicists Nima Arkani-Hamed, Savas Dimopoulos, and Gia Dvali, when they were all working at Stanford. Challenging Oskar Klein's claim that we can't see any extra dimensions due to their small size, a trio of physicists commonly referred to by the acronym ADD claimed that the extra dimensions could be larger than the Planck length, at least 10 -12 cm and , perhaps even more, up to 10 -1 cm (1 millimeter). They argued that this would be possible if our universe was "stuck" on a three-dimensional brane with an extra dimension - time, and if this three-dimensional world is all we can see.

This may seem like a rather strange argument, since the idea that the extra dimensions are very small is the assumption on which most string theory models are built. But it turns out that the generally accepted size of the Calabi-Yau space, often taken for granted, "is still an open question," Polchinski said. - Mathematicians are not interested in the size of space. In mathematics, doubling something is commonplace. But in physics, size matters because it tells you how much energy it takes to see an object.”

The ADD script not only allows you to increase the size of extra dimensions; it narrows the energy scale at which gravity and other forces become unified, and hence narrows the Planck scale. If Arkani-Hamed and his colleagues are right, then the energy generated by the collision of particles at the Large Hadron Collider can penetrate into higher dimensions, which would look like a clear violation of the laws of conservation of energy. In their model, even the strings themselves, the basic units of string theory, can become large enough to be observed - something that was previously unthinkable. The ADD team is encouraged by the opportunity to address the apparent weakness of gravity relative to other forces, given that a convincing explanation for this disparity of forces does not yet exist. The ADD theory offers a new answer: gravity is not weaker than other forces, but only seems weaker because, unlike other forces, it "leaks" into other dimensions in such a way that we feel only a tiny fraction of its true strength. An analogy can be drawn: when billiard balls collide, some of the kinetic energy of their movement, limited by the two-dimensional surface of the table, escapes in the form of sound waves into the third dimension.

Finding out the details of this leakage of energy suggests the following strategies of observation: gravity, as we know, in four-dimensional space-time obeys the inverse square law. The gravitational pull of an object is inversely proportional to the square of the distance from it. But if we add one more dimension, gravity will be inversely proportional to the cube of the distance. If we have ten dimensions, as it should be in string theory, gravity will be inversely proportional to the eighth power of the distance. In other words, the more extra dimensions there are, the weaker gravity is compared to what is measured from our 4D point of view. The electrostatic force is also inversely proportional to the square of the distance between two point charges in four-dimensional space-time, and inversely proportional to the eighth power of the distance in ten-dimensional space-time. If we consider gravity at such large distances, as is customary to operate in astronomy and cosmology, then the inverse square law works well, because in this case we are in the space of three giant dimensions plus time. We won't notice the gravitational pull in a new direction, unusual for us, which corresponds to a hidden inner dimension, until we move to a small enough scale to move in these dimensions. And since we are physically forbidden to do this, our main and probably only hope remains to look for signs of additional dimensions in the form of deviations from the inverse square law. It is this effect that physicists from the University of Washington, the University of Colorado, Stanford and other universities are looking for by making gravitational measurements at short distances.

Despite the fact that the researchers have different experimental equipment, their goals are nevertheless the same: to measure the force of gravity on a small scale with an accuracy that no one has ever dreamed of before. Eric Adelberger's team at the University of Washington, for example, is performing "torsional balance" experiments, in the spirit of those conducted by Henry Cavendish in 1798. The main goal is to infer the force of gravity by measuring the torque on a torsion pendulum.

Adelberger's group uses a small metal pendulum suspended above two metal discs that exert a gravitational force on the pendulum. The attractive forces from the two disks are balanced in such a way that if Newton's inverse square law works exactly, then the pendulum will not spin at all.

In the experiments performed so far, the pendulum has shown no sign of torsion when measured to within one tenth of a millionth of a degree. By placing the pendulum closer and closer to the disks, the researchers ruled out the existence of measurements with a radius greater than 40 microns. In his future experiments, Adelberger intends to test the inverse square law on even smaller scales, bringing the upper estimate down to 20 microns. Adelberger believes that this is not the limit. But to make measurements on even smaller scales, a different technological approach is needed.

Adelberger considers the hypothesis of large extra dimensions revolutionary, but notes that this does not make it true. We need new tactics not only to explore the question of large dimensions, but also to find answers to more general questions about the existence of extra dimensions and the validity of string theory.

This is the state of affairs today - many different ideas, of which we discussed only a small handful, and not enough sensational results to talk about. Looking to the future, Shamit Kachru, for example, hopes that a series of experiments, planned or not yet conceived, will provide many opportunities to see something new. However, he acknowledges the possibility of a less rosy scenario, suggesting that we live in a disappointing universe with few empirical clues. “If we learn nothing from cosmology, nothing from particle acceleration experiments, and nothing from laboratory experiments, then we are simply stuck,” Kachru says. Although he regards such a scenario as unlikely, since such a situation is not characteristic of either string theory or cosmology, he notes that the lack of data will affect other areas of science in a similar way.

What will we do next after we reach the end of this section of the road empty-handed? Whether this will turn out to be an even greater test for us than the search for gravitational waves in the CMF or infinitesimal deviations in measurements on torsion balances, in any case, this will be a test of our intelligence. Every time something like this happens, every time every good idea goes wrong and every road leads to a dead end, you either give up or try to come up with other questions that you can try to find answers to.

Edward Witten, who is generally conservative in his statements, looks to the future with optimism, feeling that string theory is too good not to be true. Although he acknowledges that it will be difficult to determine exactly where we are in the near future. “In order to test string theory, we must probably have a lot of luck,” he says. “It can sound like a thin string on which someone's dreams about the theory of everything are recorded, almost as thin as the cosmic string itself. But, fortunately, in physics there are many ways to get lucky.

I have no objection to this statement and I am inclined to agree with Witten because I think it is a wise policy. But if physicists decide that luck has turned against them, they may want to turn to their fellow mathematicians, who will gladly take on part of the solution to this problem.

the frequent occurrence of layers and the occurrence of layers disturbed by tectonic faults.

In geology, the inclined occurrence of rock layers is called monoclinal, and the structural forms formed by such layers are called monoclines. If, against the background of a horizontal or monoclinal occurrence of layers, an inflection occurs to a steeper occurrence, and then the layers flatten again, then such a structural form is called flexure (Fig. 3.2).

3.5.1. Folds

In addition to the noted disturbances, in the deformed volumes of the earth's crust, an occurrence is often noted, in which the layers, bending first in one direction, then in the other, form wavy structures similar to a sinusoid. Such an occurrence of layers is called folded, and individual bends are called folds.

All folds are characterized by certain structural elements that have their own names. On fig. 3.3 schematically shows one of the folds and gives the names of its elements. So, the surfaces of the layers that form the fold, inclined in different directions, are called its wings. In the given case, each individual wing of the fold is a particular case of the monoclinal occurrence of the layers. The region of sharp inflection of the layers, connecting different wings, is called the fold lock. There is no clear boundary between the wings of the fold and its lock. The fold angle is the angle formed by the planes of the wings, mentally extended until they intersect. The line passing through the points of maximum inflection of any one layer in the lock of the fold is called a hinge. The surface passing

	through the fold hinges, wire
	data on different layers, its
	setting, is axial
	fold surface. Axis warehouse
	ki is the projection of the hinge on
	horizontal plane. On
	end, interior warehouse
	ki, which stands out conditionally from
	for any layer
	called its core.
	In form and internal
	There are two types of building
	folds. In the simplest case
	convex folds
	down, are called syncli-
Rice. 3.3. The main elements of the warehouse	nasal folds, or synch-
	linalis, and the reversed convex

lost upwards - anticlinal folds, or anticlines.

However, a more reliable indication of the division of folds into synclinal and anticlinal is their internal structure. On fig. 3.4 shows block diagrams (diagrams that simultaneously show the structure of the folds in plan and in section) of the syncline and anticline folds, from which it follows that the cores of the synclines are composed of the youngest rocks, and towards the wings, the age of the layers composing the fold becomes more and more ancient. . In anticlines, the ratio of the ages of the rocks in the cores and on the limbs is directly opposite. For the analysis of folded structures, this feature is very important and should be remembered.

Shown in fig. 3.4 folds are folds with horizontal hinges. In plan view, such folds look like “bands” of rocks of different ages, arranged symmetrically with respect to the youngest and oldest formations. Such planned patterns can be observed only in small fragments of folded structures. If, however, the folded structure is studied over relatively large areas, it is easy to see that the hinges of the folds are almost never rectilinear. They are constantly bent in both horizontal and vertical planes. The bending of the hinges of the folds in the vertical plane is called undulation of hinges(Fig. 3.5). Associated with the undulation of fold hinges is the circumstance that, in plan view, coeval layers of different limbs of the same fold close at the intersection of the hinges with the relief surface, as shown

Rice. 3.4. Block diagrams of (a) synclinal and (6) anticlinal folds with horizontal hinges:

1-5 - age sequence of layers from older to younger

but in fig. 3.6. Closures in plan (on the earth's surface) of layers of different wings of synclinal folds are called centriclinal closures, or centriclines, and anticlinal - periclinal closures, or periclinals. In centriclines, the hinges of the folds at the intersection with the earth's surface "go into the air", i.e. rise, and in the periclinals "go underground", i.e. are immersed (see Fig. 3.6).

Rice. 3.7. Types of folds in plan:

a - linear S/L > 1/7; b - brachiform S/L = 1/5; c - isometric

S/L = 1/1

All folds recorded in nature are separated (classified) according to certain morphological features. There are classifications of folds observed in plan and in section.

The folds observed in the plan are divided into three classes according to the ratio of their length to width (Fig. 3.7). When the ratio of length to width is about 7-10 or more, the folds are called linear. If this ratio is between 7 and 3 - the folds are called brachiform (brachysynclines) or brachyanticlines). Folds with a length to width ratio of less than 3 are classified as isometric, with anticlines called domes and synclines called troughs. Such a division of folds is conditional, therefore, different figures of ratios can be found in different sources, but they will differ slightly from those given by us.

The classifications of folds observed in the section are more diverse. There are at least three such classifications.

1. Classification of folds according to the shape of the castle and the ratio of the wings (Fig. 3.8). In this class, the following types of folds are distinguished:

open (Fig. 3.8, a) - folds with a gentle slope of the layers on the wings; normal, or ordinary, (Fig. 3.8, b) are folds, the angle of which is close to 90 °; isoclinal, or closely compressed, (Fig. 3.8, c) - folds with a subparallel arrangement of the wings; sharp, keeled,(Fig. 3.8, d) - folds with a sharp lock; box-shaped, chest,(Fig. 3.8, e) - the lock of such folds,

Rice. 3.8. Classification of folds according to the shape of the castle and the ratio of the wings:

a - open; 6 - normal (ordinary); c - isoclinal (closely compressed); g - sharp (keeled); d - box-shaped (chest); e - fan-shaped; w -

conical; h - asymmetric

Rice. 3.9. Classification of folds according to the position of the axial surface: a - straight lines; b - inclined; in - overturned; g - recumbent; e - diving

on the contrary, it is wide, and the wings are steep; fan-shaped (Fig. 3.8, e)

Pleats with a wide lock and pinched core.

All the listed types of folds are, first, cylindrical; those in which the lines of intersection of the wings with the horizontal plane are parallel, and secondly, they are symmetrical with respect to the axial surface. However, in nature, so-called conical folds are often found (Fig. 3.8, g), in which the lines indicated above are not parallel. In addition, folds are often observed, the wings of which are not symmetrical with respect to their axial surfaces - asymmetric folds (Fig. 3.8, h).

2. Classification of folds according to the spatial position of their axial surfaces (Fig. 3.9). On this basis, the following types of folds are distinguished: straight lines (Fig. 3.9, a) - the axial surface of which is vertical or close to the vertical position; inclined (Fig. 3.9, b) - the axial surface of which is inclined and the wings are inclined in different directions; overturned (Fig. 3.9, c) - in which the axial surface is also tilted, but the wings are tilted to one side; recumbent

Rice. 3.10. Classification of folds according to the ratio of layer thicknesses

v locks and wings:

a - concentric; b - similar; c - anticlines with decreasing power

layers from wings to locks

Depiction of the disease process - a neuron affected by inclusion bodies

// wikipedia.org

Causes of Huntington's disease

Huntington's disease is caused by the expansion of the trinucleotide CAG repeat in the gene encoding the protein huntingtin. Healthy people have fewer than 36 CAG repeats, the sequence looks like this: CCAGCAGCAGCAGCAGCAGCAGCAGCAGCAG... People with Huntington's disease have 36 or more of these repeats. When the CAG repeats are translated into an amino acid, the mutant huntingtin receives an abnormally long polyglutamine tract. This type of mutation is seen in eight other neurodegenerative diseases.

An elongated polyglutamine tract imparts toxic properties to huntingtin. They may be related to the tendency of the mutant protein to aggregate or to the fact that the mutant huntingtin interferes with the normal functioning of other proteins in the cell. This leads to neurodegeneration, especially noticeable in the caudate nucleus, putamen and.

The structure of the huntingtin protein in the human body with an artificially attached maltose-binding protein

// wikipedia.org

Symptoms of Huntington's disease: chorea

On a clinical level, the patient exhibits abnormal erratic movements, cognitive decline (a form of dementia), and psychiatric abnormalities. The most obvious movement disorder seen in Huntington's disease is called chorea - abnormal short and irregular uncontrolled movements. Psychiatric symptoms of the disease, such as depression, are partly related to the biology of the disease and are not always the patient's response to its presence.

Huntington's disease usually manifests itself in the middle of life - by the age of 40. However, in cases with a very high recurrence rate, the disease may present in early childhood. In some cases, when the number of CAG repeats is close to 36, the disease manifests itself towards the end of life. The longer the trinucleotide repeat chain, the earlier signs of the disease appear. Symptoms of the disease are similar in all patients, although there may be some initial differences. The disease continues for 15–20 years until the death of the patient.

History of research into Huntington's disease

The disease is named after the American physician George Huntington, who described it in detail in 1872. "On the Chorea" is the first of two articles by Huntington in which he neatly described the signs of illness he observed in a family living on Long Island.

George Huntington (Huntington)

// wikipedia.org

However, there are earlier descriptions of Huntington's disease. James Guzella first made a connection between a disease-causing gene and the short arm of the fourth human chromosome. This is the first classic example of how you can find the location of a gene in a particular region of the chromosome, based on the study of families. The subsequent identification of the disease-causing gene by Guzella and a large consortium allowed further accurate genetic testing and provided a key resource for modeling disease in cells and animals, which is critical for developing treatments.

Treatment of Huntington's disease

Currently, there is no known treatment that alleviates human neurodegeneration, however, tetrabenazine may improve some movement disorders. It is believed that tetrabenazine does not reduce the rate of neurodegeneration in Huntington's disease. Chorea is caused by an excess of the neurotransmitter dopamine, tetrabenazine reduces its activity and reduces the symptom.

Numerous treatments for Huntington's disease are being developed at the mechanistic level. These include strategies to reduce expression of the mutant protein using antisense methods (in clinical trials) and activation. Antisense strategies involve nucleic acid oligonucleotides. They have complementary sequences to the Huntington's disease gene and reduce the amount of huntingtin synthesized. This strategy is quite rational, since the main driver of the disease is mutant huntingtin.

The prevalence of Huntington's disease

The disease affects 1 in 10,000 people in populations of European ancestry. Most often, Huntington's disease occurs in population isolates (in Venezuela), less often in some populations (for example, in the Japanese). Differences in the prevalence of the disease in populations are related to the number of gene carriers in these groups. This is a consequence of historical events, including random increases or decreases in HD carriers in population isolates.

Protective role of autophagy

In the lab, we have focused on the protective functions of autophagy in Huntington's disease and related neurodegenerative conditions. Autophagy is a process in which the internal components of a cell are delivered inside its lysosomes or vacuoles and are degraded in them.

We found that aggregating intracellular proteins (like mutated huntingtin) are substrates for autophagy. Importantly, we were the first to show that drugs that stimulate autophagy also stimulate the removal of toxic proteins. These are mutant huntingtin, mutant ataxin-3 (causing the most common spinocerebellar ataxia), alpha-synuclein (in Parkinson's disease), and wild-type and mutant tau proteins (associated with Alzheimer's disease and various types of frontotemporal dementia).

We have extended our research from cell systems to demonstrating the effectiveness of such drugs in disease models in fruit flies, zebrafish and mice. This concept has subsequently been validated by many research groups in various neurodegenerative diseases.

Our task is to develop this strategy to the status of a clinical reality. We conducted a number of studies to identify new drugs that induce autophagy. My colleague Dr. Roger Barker and I have completed testing one of the identified drugs in patients with Huntington's disease.

Huntingtin aggregates in the mouse brain (marked with arrows)

Study of the functions of huntingtin and modern therapy

There are many ongoing research projects that contribute to the study of the disease. First, the most actively developed question is how mutant huntingtin causes disease. To answer it, you need to use the methods of structural biology, biophysics, genetic scanning, cell biology and animal models. Some groups are focusing on examining the disease at the biochemical level, trying to understand the structure of the mutant protein and its early aggregating species. Others use cellular, neural, and stem cell models to understand what the mutated protein is doing. They are complemented by animal studies: worms, fruit flies, zebrafish, mice, rats, and even primates and sheep. This is necessary to develop models that will allow us to understand the disease at the level of the body. These models can be used to test therapeutic strategies.

Secondly, it is necessary to understand what the functions of normal huntingtin are - they are poorly understood. To shed light on these functions, research groups are using different approaches based on cellular modeling. This may affect therapeutic strategies and/or our overall understanding of how the cell works.

The third goal is to identify potential targets of therapy to alleviate the disease, improving existing treatment strategies. Various research groups are working on this issue; they use chemical and genetic scanning techniques to identify new targets and potential drugs.

The fourth goal is to identify and characterize biomarkers of disease progression to facilitate clinical trials. This will make it possible to track the benefits of any therapeutic strategy. It would be effective to have a very sensitive scale of disease progression with a short time interval. This is important for those who carry the disease gene but do not yet have obvious signs and symptoms. In this case, it will be possible to test the effects of potential therapeutic agents that slow down the development of the disease.

This is a translation of an article from our English edition of Serious Science. You can read the original version of the text here.