On the possibility to supercool molecular hydrogen down to superfluid transition

Recent calculations by Vorobev and Malyshenko (JETP Letters, 71, 39, 2000) show that molecular hydrogen may stay liquid and superfluid in strong electric fields of the order of $4\times 10^7 V/cm$. I demonstrate that strong local electric fields of similar magnitude exist beneath a two-dimensional layer of electrons localized in the image potential above the surface of solid hydrogen. Even stronger local fields exist around charged particles (ions or electrons) if surface or bulk of a solid hydrogen crystal is statically charged. Measurements of the frequency shift of the $1 \to 2$ photoresonance transition in the spectrum of two-dimensional layer of electrons above positively or negatively charged solid hydrogen surface performed in the temperature range 7 - 13.8 K support the prediction of electric field induced surface melting. The range of surface charge density necessary to stabilize the liquid phase of molecular hydrogen at the temperature of superfluid transition is estimated.Comment: 5 pages, 2 figure

Radiation of a Charge Exiting Open-Ended Waveguide with Dielectric Filling

We consider a semi-infinite open-ended cylindrical waveguide with uniform dielectric filling placed into collinear infinite vacuum waveguide with larger radius. Electromagnetic field produced by a point charge or Gaussian bunch moving along structure's axis from the dielectric waveguide into the vacuum one is investigated. We utilize the modified residue-calculus technique and obtain rigorous analytical solution of the problem by determining coefficients of mode excitation in each subarea of the structure. Numerical simulations in CST Particle Studio are also performed and an excellent agreement between analytical and simulated results is shown. The main attention is paid to analysis of Cherenkov radiation generated in the inner dielectric waveguide and penetrated into vacuum regions of the outer waveguide. The discussed structure can be used for generation of Terahertz radiation by modulated bunches (bunch trains) by means of high-order Cherenkov modes. In this case, numerical simulations becomes difficult while the developed analytical technique allows for efficient calculation of the radiation characteristics.Comment: 13 pages, 11 figure

Test beam studies of the TRD prototype filled with different gas mixtures based on Xe, Kr, and Ar

Towards the end of LHC Run1, gas leaks were observed in some parts of the Transition Radiation Tracker (TRT) of ATLAS. Due to these leaks, primary Xenon based gas mixture was replaced with Argon based mixture in various parts. Test-beam studies with a dedicated Transition Radiation Detector (TRD) prototype were carried out in 2015 in order to understand transition radiation performance with mixtures based on Argon and Krypton. We present and discuss the results of these test-beam studies with different active gas compositions.Comment: 5 pages,12 figures, The 2nd International Conference on Particle Physics and Astrophysics (ICPPA-2016); Acknowledgments section correcte

Some results of test beam studies of Transition Radiation Detector prototypes at CERN

Operating conditions and challenging demands of present and future accelerator experiments result in new requirements on detector systems. There are many ongoing activities aimed to develop new technologies and to improve the properties of detectors based on existing technologies. Our work is dedicated to development of Transition Radiation Detectors (TRD) suitable for different applications. In this paper results obtained in beam tests at SPS accelerator at CERN with the TRD prototype based on straw technology are presented. TRD performance was studied as a function of thickness of the transition radiation radiator and working gas mixture pressure

Analysis of nucleus-nucleus collisions at high energies and Random Matrix Theory

We propose a novel statistical approach to the analysis of experimental data obtained in nucleus-nucleus collisions at high energies which borrows from methods developed within the context of Random Matrix Theory. It is applied to the detection of correlations in momentum distributions of emitted particles. We find good agreement between the results obtained in this way and a standard analysis based on the method of effective mass spectra and two-pair correlation function often used in high energy physics. The method introduced here is free from unwanted background contributions.Comment: 11 pages, 10 figure

A consecutive power dispatch in wind farms to mitigate secondary frequency dips

\ua9 2024 The AuthorsWith the rapid increase of wind energy integrated into power systems, wind turbine generators (WTGs) are required to provide frequency support to maintain the system frequency stability. However, the frequency regulation is achieved by employing temporary energy reserves from WTGs at the initial stage of a disturbance. Therefore, a second frequency dip (SFD) may occur, if no other energy reserve is available to compensate the power deficiency as WTGs have to recover their operating points and rotor speeds back to the initial operating points. To deal with this problem, this paper proposes a consecutive power dispatch scheme to reduce the SFD and prevent WTGs from over-deceleration. All WTGs are divided into two groups with in a wind farm: Group 1 (G1) WTGs operating at maximum power point tracking (MPPT), Group 2 (G2) WTGs operating at deloading power. If a frequency contingency occurs, the proposed scheme aims to release an amount of kinetic energy (KE) stored in the rotating masses of G1 WTGs to improve the frequency nadir (FN). Following this, energy reserves are released from G2 WTGs to compensate the power shortage during the period when G1 WTGs rotor speeds have to be recovered. The simulation results show that the scheme causes a small SFD while improving the first FN and preventing the rotor from over-decelerations in various wind conditions, contingency sizes, and wind penetration levels

Current Issues in Terminology and Classification of Hereditary Disorders at Endocrine Cancer

Significant interest in the problem of genetic oncological diseases is due to an increase in the frequency of their detection, existing difficulties of early recognition, disagreements in the clinical and morphological criteria for diagnosis and evaluation of prognostic factors, the absence of generally accepted standards of treatment and objective assessment of their results.The introduction of new diagnostic technologies into clinical practice (molecular genetic studies, the ability to determine a wide range of hormones and peptides, immunohistochemical determination of general and specific markers, modern methods of topical diagnostics, etc.) allowed us to identify a specific genetic substrate of various types of endocrine organ tumors, previously unknown nosological forms, improve the ability to predict the disease on the preclinical level, to assess their place and importance in the structure of general oncopathology.The issues of terminology, classification, criteria for the degree of malignancy and prognostic factors of hereditary endocrine diseases are particularly relevant. The article presents and analyzes the modern classification and terminological definitions of this group of diseases. The problem of hereditary endocrine tumor diseases and syndromes associated with neuroendocrine tumors (NETs) and multiple endocrine neoplasia syndromes (MEN-syndromes) has been described. In conclusion, the situation with the study of this problem in the Russian Federation is analyzed

Спорные вопросы ведения пациентов с инфарктом миокарда второго типа

Highlights. The article presents relevant literary data on the epidemiology, main causes, approaches to the diagnostics and treatment of type 2 myocardial infarction patients. The authors emphasize an unfavorable prognosis in these patients due to comorbidity that leads to development of myocardial infarction. They highlight the need to improve and unify approaches to identifying this phenomenon, as well as the necessity to conduct observational and randomized studies to evaluate approaches to the treatment of type 2 myocardial infarction patients.Abstract. The article summarizes the available data from clinical trials and current guidelines, approaches to the definition and type 2 myocardial infarction (MI) differential diagnosis in clinical practice. The attention is focused on the fundamental difference between type 1 and type 2 MI and the need to consider the comorbidities for the identification of etiological factors type 2 MI development. The lack of evidencebased medical data regarding the prognosis and effective treatment of patients with type 2 MI is emphasized. Nevertheless, such patients are characterized with high rates of overall and cardiovascular mortality in hospital and long-term disease course, as well as a high rate of readmission. Thus, there is the need for multicenter observational studies of type 2 MI patients and the development of algorithms for treatment and rehabilitation of this category of patients.Основные положения. Представлены актуальные литературные данные об эпидемиологии и основных причинах возникновения инфаркта миокарда 2-го типа, описаны методы диагностики и лечения пациентов данной группы. Подчеркнуты неблагоприятный прогноз больных из-за коморбидности, способствующей развитию инфаркта миокарда, необходимость усовершенствования и унификации подходов к выявлению заболевания, а также проведения наблюдательных и рандомизированных исследований для оценки тактики ведения пациентов с инфарктом миокарда 2-го типа.Резюме. В обзорной статье на основании данных клинических исследований и действующих рекомендаций актуализированы подходы к определению и дифференциальной диагностике инфаркта миокарда (ИМ) 2-го типа в клинической практике. Акцентировано внимание на принципиальном различии ИМ 1-го и 2-го типов и необходимости оценки коморбидного фона для выявления этиологических факторов развития ИМ 2-го типа. Подчеркнут дефицит данных доказательной медицины в отношении прогноза и эффективности методов лечения пациентов с ИМ 2-го типа. При этом такие больные характеризуются высокими показателями общей и сердечно-сосудистой смертности в госпитальном и отдаленном периодах заболевания, а также высокой частотой повторных госпитализаций. Таким образом, высокую важность представляют необходимость многоцентровых обсервационных исследований пациентов с ИМ 2-го типа и разработка алгоритмов лечения и реабилитации данной категории больных