Comment on Zeeman-Driven Lifshitz Transition: A Model for the Experimentally Observed Fermi-Surface Reconstruction in YbRh2Si2 (A. Hackl and M. Vojta, Phys. Rev. Lett. 106, 137002 (2011))

Comment on Zeeman-Driven Lifshitz Transition: A Model for the Experimentally Observed Fermi-Surface Reconstruction in YbRh2Si2 by A. Hackl and M. Vojta, Phys. Rev. Lett. 106, 137002 (2011).Comment: 1 pag

Universal Behavior of Heavy-Fermion Metals Near a Quantum Critical Point

The behavior of the electronic system of heavy fermion metals is considered. We show that there exist at least two main types of the behavior when the system is nearby a quantum critical point which can be identified as the fermion condensation quantum phase transition (FCQPT). We show that the first type is represented by the behavior of a highly correlated Fermi-liquid, while the second type is depicted by the behavior of a strongly correlated Fermi-liquid. If the system approaches FCQPT from the disordered phase, it can be viewed as a highly correlated Fermi-liquid which at low temperatures exhibits the behavior of Landau Fermi liquid (LFL). At higher temperatures $T$, it demonstrates the non-Fermi liquid (NFL) behavior which can be converted into the LFL behavior by the application of magnetic fields $B$. If the system has undergone FCQPT, it can be considered as a strongly correlated Fermi-liquid which demonstrates the NFL behavior even at low temperatures. It can be turned into LFL by applying magnetic fields $B$. We show that the effective mass $M^*$ diverges at the very point that the N\'eel temperature goes to zero. The $B-T$ phase diagrams of both liquids are studied. We demonstrate that these $B-T$ phase diagrams have a strong impact on the main properties of heavy-fermion metals such as the magnetoresistance, resistivity, specific heat, magnetization, volume thermal expansion, etc.Comment: Revtex, 11 pages, revised and accepted by JETP Let

NECESSITY OF AGE-RELATED STANDARDS FOR IMMUNE PHENOTYPING OF BLOOD CELLS FOR MONITORING OF HEALTH IN CHILDREN BORN BY HIV-INFECTED WOMEN

Considering the increase in number of HIV-infected women of childbearing age this study was aimed at a comparison of CD-phenotype of children born by infected mothers with age standards obtained during the analysis of the functional state of the immune system of healthy children differing by sex and age in the Perm region. 133 children from infected mothers at the age from 1 month to 4 years and 53 clinically healthy children were examined. Among the peripheral blood lymphocytes of children the numbers of CD3+-T-lymphocytes, CD3+CD4+-T-helpers, CD3+CD8+-cytotoxic T-lymphocytes, CD3-CD19+-B-lymphocytes, CD3-CD16+/56+-NK-cells were identified. The increase in the functional activity of the immune system of the risk group was reliably determined. In HIV-positive children of 1 to 6 months and 1 to 4 years the increase in the absolute number of leukocytes, lymphocytes, T-lymphocytes, cytotoxic T-lymphocytes, B-lymphocytes was oserved as compared with their healthy coevals. By contrast, under similar comparison within the age group of 6 to 12 months the decrease in percentage of lymphocytes and absolute number of NK-cells was determined. Gender-based division of children under study supported the necessity in taking into account this factor yet in this early age. It was shown that both in perinatal contact and under the progression of HIV infection the reaction of male and female bodies differed. Data obtained from the phenotyping of blood from healthy children in the city of Perm were compared with those provided from American and Chinese investigations. Resulting differences primarily depended on the age range of the children and were frequently related to the absolute cell number that expressed definite markers. Results evidence for the necessity in further temporal specification under the assessment of the state of the immune system in children, and allow developing new criteria for immune system monitoring under the risk of vertical route of HIV infection

Universal behavior of CePd1−xRhx\rm CePd_{1-x}Rh_x Ferromagnet at Quantum Critical Point

The heavy-fermion metal $\rm CePd_{1-x}Rh_x$ can be tuned from ferromagnetism at $x=0$ to non-magnetic state at some critical concentration $x_c$. The non-Fermi liquid behavior (NFL) at $x\simeq x_c$ is recognized by power low dependence of the specific heat $C(T)$ given by the electronic contribution, magnetic susceptibility $\chi(T)$ and volume expansion coefficient $\alpha(T)$ at low temperatures: $C/T\propto\chi(T)\propto\alpha(T)/T\propto1/\sqrt{T}$. We also demonstrate that the behavior of normalized effective mass $M^*_N$ observed in $\rm CePd_{1-x}Rh_x$ at $x\simeq 0.8$ agrees with that of $M^*_N$ observed in paramagnetic $\rm CeRu_2Si_2$ and conclude that these alloys exhibit the universal NFL thermodynamic behavior at their quantum critical points. We show that the NFL behavior of $\rm CePd_{1-x}Rh_x$ can be accounted for within frameworks of quasiparticle picture and fermion condensation quantum phase transition, while this alloy exhibits a universal thermodynamic NFL behavior which is independent of the characteristic features of the given alloy such as its lattice structure, magnetic ground state, dimension etc.Comment: 5 pages, 3 figure

Spontaneous breaking of four-fold rotational symmetry in two-dimensional electronic systems explained as a continuous topological transition

The Fermi liquid approach is applied to the problem of spontaneous violation of the four-fold rotational point-group symmetry ($C_4$) in strongly correlated two-dimensional electronic systems on a square lattice. The symmetry breaking is traced to the existence of a topological phase transition. This continuous transition is triggered when the Fermi line, driven by the quasiparticle interactions, reaches the van Hove saddle points, where the group velocity vanishes and the density of states becomes singular. An unconventional Fermi liquid emerges beyond the implicated quantum critical point.Comment: 6 pages, 4 figure

Adaptation of the Landau-Migdal Quasiparticle Pattern to Strongly Correlated Fermi Systems

A quasiparticle pattern advanced in Landau's first article on Fermi liquid theory is adapted to elucidate the properties of a class of strongly correlated Fermi systems characterized by a Lifshitz phase diagram featuring a quantum critical point (QCP) where the density of states diverges. The necessary condition for stability of the Landau Fermi Liquid state is shown to break down in such systems, triggering a cascade of topological phase transitions that lead, without symmetry violation, to states with multi-connected Fermi surfaces. The end point of this evolution is found to be an exceptional state whose spectrum of single-particle excitations exhibits a completely flat portion at zero temperature. Analysis of the evolution of the temperature dependence of the single-particle spectrum yields results that provide a natural explanation of classical behavior of this class of Fermi systems in the QCP region.Comment: 26 pages, 14 figures. Dedicated to 100th anniversary of A.B.Migdal birthda

Морфологические свидетельства анаболического действия препарата «Гистохром» у крыс

The aim of the investigation was to assess histochrome’s anabolic effect as a consequence of treatment of various doses in rats in conditions of prolonged physical training.Materials and methods. The experiments were performed on the Wistar’s rats. Experimental Group 1 was subcutaneously injected with histochrome in a dose of 1 mg/kg (n = 20) within 10 days, experimental group 2 was treated subcutaneously at a dose of 10 mg/kg (n = 20), and control group 3 received equivolume injections of isotonic sodium chloride (n = 20). Rat musclehypertrophy was induced using the method of forced swimming. A piece ofmuscle  was takenfor morphological examination a day after the first and last period of swimming. Hypertrophy of muscle fibers was evaluated by the cross-sectional diameter of muscle fibers, the average quantity of argyrophilic nucleolar organizer region (AgNOR) proteins and the percentage of nuclei with 1, 2, 3 or more AgNOR compared to intact (control) animals.Results. Microscopic morphological examination of M. gastrocnemius registered increase in diameter of muscle fiber by 19,4% (1 mg/kg) and by 60% (10 mg/kg). In the control group of rats an increase in a transverse section of muscle fibers was not found to be statistically significant.The study of biosynthetic nuclei activity of myosimplastus registered increase the AgNOR proteins in both examines groups of animals in comparison the less dynamics in control one. By 10th day of observation the quantity of myosimplastus with two AgNOR increased in a control group of rats by 10%. The maximum AgNOR proteins gained was marked in case of the prolonged use of histochrome in a dose 1 mg/kg.Conclusion. Histochrome enables the increase in dose-dependent biosynthetic processes in skeletal muscles of rats, providing the development of anabolic effect.Цель. Изучить анаболическое действие различных доз гистохрома у крыс в условиях длительных физических тренировок.Материалы и методы. Эксперименты выполнены на аутбредных крысах сток Вистар обоего пола в возрасте 2–3 мес и весом 200–300 Крысам группы 1 (n = 20) в течение 10 сут подкожно вводили гистохром в дозе 1 мг/кг, группы 2 (n = 20) – 10 мг/кг, группы 3 (n = 20) – эквиобъемные инъекции изотонического раствора натрия хлорида (контроль). Гипертрофические процессы в мускулатуре крыс индуцировали, используя модель принудительного плавания. Тренировки проводили через 1 сут. Забор материала для морфологического исследования осуществляли через 1 сут после первого и последнего плавания. Гипертрофию мышечных волокон оценивали по диаметру поперечного сечения мышечных волокон, среднему количеству гранул серебра на одно ядро миосимпласта и процентному содержанию ядер с 1–3 и более гранулами в сравнении с интактными (контрольными) животными.Результаты. При морфологическом исследовании микропрепарата m. gastrocnemius зарегистрировано увеличение диаметра мышечного волокна на 19,4% в группе 1 и на 60% в группе 2. В контрольной группе крыс не обнаруживалось статистически значимого увеличения поперечного сечения мышечных волокон.Изучение биосинтетической активности ядер миосимпластов выявило увеличение аргирофильных белков (AgNORs) в обеих испытуемых группах животных при менее яркой динамике в контроле.  К 10-м сут наблюдения в контрольной группе крыс на 10% возросло количество миосимпластов с двумя ядрышковыми организаторами. Максимальный прирост аргирофильных гранул отмечался при длительном применении препарата «Гистохром» в дозе 1 мг/кг.Заключение. Гистохром дозозависимо повышает биосинтетические процессы в скелетной мускулатуре крыс, обеспечивая развитие анаболического эффекта