Hamiltonian analysis of SO(4,1) constrained BF theory

In this paper we discuss canonical analysis of SO(4,1) constrained BF theory. The action of this theory contains topological terms appended by a term that breaks the gauge symmetry down to the Lorentz subgroup SO(3,1). The equations of motion of this theory turn out to be the vacuum Einstein equations. By solving the B field equations one finds that the action of this theory contains not only the standard Einstein-Cartan term, but also the Holst term proportional to the inverse of the Immirzi parameter, as well as a combination of topological invariants. We show that the structure of the constraints of a SO(4,1) constrained BF theory is exactly that of gravity in Holst formulation. We also briefly discuss quantization of the theory.Comment: 9 page

MacDowell-Mansouri gravity and Cartan geometry

The geometric content of the MacDowell-Mansouri formulation of general relativity is best understood in terms of Cartan geometry. In particular, Cartan geometry gives clear geometric meaning to the MacDowell-Mansouri trick of combining the Levi-Civita connection and coframe field, or soldering form, into a single physical field. The Cartan perspective allows us to view physical spacetime as tangentially approximated by an arbitrary homogeneous "model spacetime", including not only the flat Minkowski model, as is implicitly used in standard general relativity, but also de Sitter, anti de Sitter, or other models. A "Cartan connection" gives a prescription for parallel transport from one "tangent model spacetime" to another, along any path, giving a natural interpretation of the MacDowell-Mansouri connection as "rolling" the model spacetime along physical spacetime. I explain Cartan geometry, and "Cartan gauge theory", in which the gauge field is replaced by a Cartan connection. In particular, I discuss MacDowell-Mansouri gravity, as well as its more recent reformulation in terms of BF theory, in the context of Cartan geometry.Comment: 34 pages, 5 figures. v2: many clarifications, typos correcte

NMDB database and global survey method

The method of a global survey developed in the 1970s allows using a world-wide network of neutron monitor stations as a single multidirectional device. Wherein, receiving characteristics of each device, which reflects their geometries and geographical positions, are taken into account. Such an approach makes it possible to define the first two angular moments of the distribution function of cosmic rays in the interplanetary space at each hour of observation. With the creation in 2008/2009 and subsequent development of an international database of neutron monitors NMDB, for the first time it appeared an opportunity to use the global survey method in real-time mode. Such a situation creates a unique possibility to use the results not only for scienti- fic researches but also for space weather forecasting. To use the data of the world-wide network of neutron monitors it is necessary to carry preliminary preparations. Thereby, in the current work, the main attention is attracted to a solution to some practical questions that arise when using the NMDB in real-time

NMDB and space weather forecasting

From the creation of NMDB in 2007 and through the growth in the number of stations and the data accumulation, the ShICRA SB RAS group continuously have used its facilities. For the last years we have created a method for short-term forecasting of intense geomagnetic storms with an advance time 1-2 days. The probability of forecasting is around 80%. We have reported about the method in the previous NMDB: virtual symposium on cosmic ray studies with neutron detectors in 2020. The method is based on the global survey method that was developed in Yakutsk in 1960s and uses the world network of neutron monitors as a single multidirectional device. The method is intended to estimate hourly dynamics of cosmic ray anisotropy in free-space. Note that only with the NMDB creation we managed to implement it in real time mode. Now we started work on creating another method for space weather forecasting by measurements of cosmic ray fluctuations. For this purpose, we use 1-min data of NMDB. In the current report we present the first results of our investigation on forecasting of intense geomagnetic storms with Dst < -50 nT. The results obtained indicate the possibility of developing and implementing in real time a method for predicting strong geophysical manifestations of space weather on the basis of ground-based cosmic ray measurements

Neuroimmunological mechanisms of chronic pain syndrome

The article considers the mechanisms of chronic low back pain. Three pathophysiological mechanisms: nociceptive, neurogenic (neuropathic), and psychogenic are noted to be involved in the development of pain syndrome. The role of cellular and molecular changes in the posterior horn and in the somatosensory dysregulated mechanism of neuropathic pain is shown. Immunological processes, including neurohumoral (serotoninergic) and hormonal (sex hormones and specific proteins) ones, play an important role in the development of pain. The generalization and further study of these mechanisms are embodied in approaches to therapy for pain syndromes and hence these require analysis and further investigation

Radiation Tolerance of Single-Sided Microstrip Detector with Si3N4Si_{3}N_{4} Insulator

The ALICE Collaboration is investigating the radiation tolerance and operation of silicon microstrip detectors for the inner tracking system. Detectors with and without an additional layer of Si3N4 insulator were made in one set, using the same thickness of SiO2 insulator. Measurements were made on both types of detectors after irradiation with 20 MeV electrons, using doses up to 2Mrad. The additional Si3N4 layer allows a coupling capacitor breakdown voltage larger than 100 V and capacitor yield larger than 99 percent. However, the leakage current for detectors with double layer insulator is about 20 nA per strip while the leakage current for the single layer SiO2 insulated detectors is only 0.5 nA. The 20 nA leakage current leads to 450 electrons noise when the ALICE 128C electronics with a peaking time of 1.4 microseconds is used. At a 1 nA leakage current the noise is 100 electrons. The ENC for an input capacitance of 5 pF is 300 electrons. Since all detectors show an increased leakage current after irradiation, the difference between the single and duoble layer insulation detectors becomes negligible when doses of the order of several hundreds of krad are applied

Interstrip resistance of a semiconductor microstrip detector

In this work the interelement (interstrip) resistance of the microstrip detector is studied. A few detectors with a different construction are investigated. The dependence of the interstrip resistance on the dose of detector irradiation with electrons is obtained. The possibility of application interstrip resistance measurement for the determination of the good strip yield is shown

Cosmic ray angular distribution dynamics during Forbush decrease in 3-4 November 2021

On November 3-4, 2021, there was a coronal ejection of the solar mass into the interplanetary medium. According to direct observations of the interplanetary magnetic field and the solar wind, the ejection was accompanied by a magnetic cloud. During the event, neutron monitors of the NMDB network registered a two-stage Forbush decrease with a total amplitude of up to 15%. A preliminary analysis of the NMDB data shows that the first step was due to the cosmic ray decrease behind the shock wave front, while the second step was due to the cosmic ray anisotropy formed in the magnetic cloud. This work was undertaken to study the dynamics of the angular distribution of cosmic rays in this event. The cosmic ray distribution was determined using the global survey method developed at the ShICRA in the 1960s. The method makes it possible to use the worldwide network of neutron monitors as a single multidirectional instrument and to determine the hourly dynamics of CR distribution. It is shown that unidirectional and bidirectional anisotropies of significant amplitude are observed inside the magnetic cloud. The results obtained are discussed in the framework of modern theories of the formation of magnetic clouds. The temporal dynamics of the spatial-angular distribution of cosmic rays during the Forbush decrease on November 3–4, 2021 was determined. The presence of cosmic ray anisotropy with an amplitude comparable to the magnitude of the density decrease itself was found