Cross-relaxation and phonon bottleneck effects on magnetization dynamics in LiYF4:Ho3+

Frequency and dc magnetic field dependences of dynamic susceptibility in diluted paramagnets LiYF$_4$:Ho$^{3+}$ have been measured at liquid helium temperatures in the ac and dc magnetic fields parallel to the symmetry axis of a tetragonal crystal lattice. Experimental data are analyzed in the framework of microscopic theory of relaxation rates in the manifold of 24 electron-nuclear sublevels of the lowest non-Kramers doublet and the first excited singlet in the Ho$^{3+}$ ground multiplet $^5I_8$ split by the crystal field of S$_4$ symmetry. The one-phonon transition probabilities were computed using electron-phonon coupling constants calculated in the framework of exchange charge model and were checked by optical piezospectroscopic measurements. The specific features observed in field dependences of the in- and out-of-phase susceptibilities (humps and dips, respectively) at the crossings (anti-crossings) of the electron-nuclear sublevels are well reproduced by simulations when the phonon bottleneck effect and the cross-spin relaxation are taken into account

Possible Method for Measuring the Proton Form Factors in Processes with and without Proton Spin Flip

The ratio of the squares of the electric and magnetic proton form factors is shown to be proportional to the ratio of the cross sections for the elastic scattering of an unpolarized electron on a partially polarized proton with and without proton spin flip. The initial proton at rest should be polarized along the direction of the motion of the final proton. Similar results are valid for both radiative $ep$ scattering and the photoproduction of pairs on a proton in the Bethe--Heitler kinematics. When the initial proton is fully polarized in the direction of the motion of the final proton, the cross section for the $ep \to ep$ process, as well as for the $ep \to ep \gamma$ and $\gamma p \to e \bar e p$ processes, without (with) proton spin flip is expressed only in terms of the square of the electric (magnetic) proton form factor. Such an experiment on the measurement of the cross sections without and with proton spin flip would make it possible to acquire new independent data on the behavior of $G_E^2(Q^2)$ and $G_M^2(Q^2)$, which are necessary for resolving the contradictions appearing after the experiment of the JLab collaboration on the measurement of the proton form factors with the method of polarization transfer from the initial electron to the final proton.Comment: 7 pages, revtex

Broadband optical gain via interference in the free electron laser: principles and proposed realizations

We propose experimentally simplified schemes of an optically dispersive interface region between two coupled free electron lasers (FELs), aimed at achieving a much broader gain bandwidth than in a conventional FEL or a conventional optical klystron composed of two separated FELs. The proposed schemes can {\it universally} enhance the gain of FELs, regardless of their design when operated in the short pulsed regime

Polarized triplet production by circularly polarized photons

A process of the pair production by a circularly polarized photon in the field of unpolarized atomic electron has been considered in the Weizaecker-Williams approximation. The degree of longitudinal polarization of positron and electron has been calculated. An exclusive cross-section as well as a spectral distribution are obtained. We estimate the accuracy of our calculations at the level of a few percent. We show the identity of the positron polarization for considered process and for process of pair production in the screened Coulomb field of nucleus.Comment: 9 pages, 3 picture

One-dimensional Model of a Gamma Klystron

A new scheme for amplification of coherent gamma rays is proposed. The key elements are crystalline undulators - single crystals with periodically bent crystallographic planes exposed to a high energy beam of charged particles undergoing channeling inside the crystals. The scheme consists of two such crystals separated by a vacuum gap. The beam passes the crystals successively. The particles perform undulator motion inside the crystals following the periodic shape of the crystallographic planes. Gamma rays passing the crystals parallel to the beam get amplified due to interaction with the particles inside the crystals. The term `gamma klystron' is proposed for the scheme because its operational principles are similar to those of the optical klystron. A more simple one-crystal scheme is considered as well for the sake of comparison. It is shown that the gamma ray amplification in the klystron scheme can be reached at considerably lower particle densities than in the one-crystal scheme, provided that the gap between the crystals is sufficiently large.Comment: RevTeX4, 22 pages, 4 figure

Surgical treatment of patients with symptomatic Kimmerle's anomaly using video endoscopy

Background: Clinical manifestations of Kimmerle’s anomaly are detected in 5.5 to 20% of patients. The main reason for the development of symptoms is prolonged compression of the V3 (atlantic) segment of the vertebral artery in the bone ring as a result of the atlantooccipital membrane’s exostosis. To date, the final tactics for treating patients with Kimmerle’s anomaly has not been determined. The effectiveness of conservative methods of therapy does not exceed 40%. The aim Of this study was to evaluate the results of a minimally invasive surgical treatment of patients with symptomatic Kimmerle’s anomaly using video endoscopic assistance. Methods: In the period from 2020 to 2022, 15 patients were operated on. The indication for the surgical treatment was the lack of the conservative therapy’s effect for 1 year from the onset of the disease, aggravation of the disease symptoms, a decrease in the blood flow through the vertebral artery at the Kimmerle’s anomaly side when turning the head. The vertebral artery decompression was performed using video endoscopy through a posterior median approach in two (13%) patients and through a paravertebral intermuscular approach (4 cm incision in the occipitocervical region in the projection of the Kimmerle’s anomaly) in thirteen (87%) patients. Results: The outcome of the disease was assessed at the time of discharge from the hospital, as well as in 6 and in 12 months after the operation. Following the surgical treatment, all the patients showed the complete regression of symptoms and restoration of the blood flow velocities in the vertebral artery. There were no complications after the operation. The use of video endoscopy made it possible to reduce the size of the surgical wound from 12 cm to 4 cm, which contributed to a decrease in the intensity of pain in the postoperative period, early activation and a decrease in the duration of the inpatient treatment. Conclusion: With the proper selection of patients with Kimmerle’s anomaly, decompression of the V3 segment of the VA using video endoscopy is a safe and effective method of treatment

Staffing support and results of work of health care centers for adults

The article shows the results ot a study aiming at evaluating the level of medical staffing support of the Health care centers (HCC) for adults located in the South administrative district (SAD) of Moscow and in Sverdlovsk oblast. It was estimated, that the level of staff density of both doctors and nurses was higher in Sverdlovsk oblast, while in HCC of SAD of Moscow it was below the standard. In 2015 the number of personnel has reduced in HCC of SAD of Moscow and it can be explained by the staff optimization in the heath care system as a whole. It was also noted that the change-over to per-capital financial approach in HCC of SAD of Moscow initiated the worsening of work results.В статье приведены результаты исследования по оценке обеспечения медицинским персоналом Центров здоровья (ЦЗ) для взрослого населения, расположенных в Южном административном округе (ЮАО) г. Москвы и Свердловской области. Установлено, что уровень обеспеченности населения врачами и средними медицинскими работниками ЦЗ в настоящее время в Свердловской области выше, а в ЮАО Москвы ниже действующего норматива. В 2015 г. в ЦЗ ЮАО г.Москвы отмечено сокращение численности персонала, обусловленное проводившейся в городе кадровой оптимизацией в системе здравоохранения. Показано, что переход на подушевой принцип финансирования ЦЗ в г. Москве привел к снижению результативности работы

Drawing Boundaries

In “On Drawing Lines on a Map” (1995), I suggested that the different ways we have of drawing lines on maps open up a new perspective on ontology, resting on a distinction between two sorts of boundaries: fiat and bona fide. “Fiat” means, roughly: human-demarcation-induced. “Bona fide” means, again roughly: a boundary constituted by some real physical discontinuity. I presented a general typology of boundaries based on this opposition and showed how it generates a corresponding typology of the different sorts of objects which boundaries determine or demarcate. In this paper, I describe how the theory of fiat boundaries has evolved since 1995, how it has been applied in areas such as property law and political geography, and how it is being used in contemporary work in formal and applied ontology, especially within the framework of Basic Formal Ontology

Long-term results of microvascular decompression with video endoscopy in the treatment of patients with atypical trigeminal neuralgia

Background: The incidence of atypical trigeminal neuralgia (aNTN) varies from 1 to 7 per 100,000 population per year. The main cause of its development is compression of the trigeminal nerve (TN) root by a vein and/or artery in the cerebellar cistern. To date, the final tactics of treatment for patients with aNTN has not been specified. The effectiveness of conservative methods of therapy does not exceed 50%. The aim of this study was to evaluate the results of microvascular decompression using video endoscopy in the treatment of patients with atypical trigeminal neuralgia. Methods: In the period from 2014 to 2021, 34 patients with aNTN were operated on, of which 18 (53%) patients had neuropathic pain (more than 4 points on the DN4 scale), and 15 (44%) patients had transformation of classical trigeminal neuralgia into atypical neuralgia. The conservative therapy (carbamazepine, gabapentin, pregabalin), administered to all the patients in the preoperative period, was not accompanied by a significant relief of pain syndrome. The maximum intensity of pain upon admission to the hospital was, according to the visual analog scale (VAS), 10 points, according to the BNI (Barrow Neurological Institute) Pain Intensity Scale V (severe, persistent pain). All the patients underwent microvascular decompression of the trigeminal nerve root with the use of Teflon; in 12 (35%) patients, in addition to microscopy, video endoscopy was used. The average follow-up period after the surgery was 3.41.7 years (from 1 to 5 years). Results: In all (100%) patients, the pain was completely eliminated (BNI I) after the surgery. A total five-year excellent and good outcome of the disease on the J. Miller and BNI scale (I -II) was noted in 80% (n=27) of patients with aNTN. The risk of pain recurrence after microvascular decompression was 14% (n=3) in the first three years, and 34% (n=4) after 5 years. The use of video endoscopy made it possible to identify the blood vessels compressing the root of the trigeminal nerve with a minimal displacement of the cerebellum and cranial nerves when visualizing the neurovascular conflict. Conclusion: The microvascular decompression method with video endoscopy is effective in the treatment of patients with aNTN

Progress with FEL-based coherent electron cooling

Cooling intense high-energy hadron beams remains a major challenge for accelerator physics. Synchrotron radiation is too feeble, while efficiency of two other cooling methods falls rapidly either at high bunch intensities (i.e. stochastic cooling of protons) or at high energies (i.e. e-cooling). The possibility of coherent electron cooling, based on high-gain FEL and ERL, was presented at last FEL conference [1]. This scheme promises significant increases in luminosities of modern high-energy hadron and electron-hadron colliders, such as LHC and eRHIC. In this paper we report progress made in the past year on the development of this scheme of coherent electron cooling (CeC), results of analytical and numerical evaluation of the concept as well our prediction for LHC and RHIC. We also present layout for proof-of-principle experiment at RHIC using our R&D ERL which is under construction