Absence of Conventional Spin-Glass Transition in the Ising Dipolar System LiHo_xY_{1-x}F_4

The magnetic properties of single crystals of LiHo_xY_{1-x}F_4 with x=16.5% and x=4.5% were recorded down to 35 mK using a micro-SQUID magnetometer. While this system is considered as the archetypal quantum spin glass, the detailed analysis of our magnetization data indicates the absence of a phase transition, not only in a transverse applied magnetic field, but also without field. A zero-Kelvin phase transition is also unlikely, as the magnetization seems to follow a non-critical exponential dependence on the temperature. Our analysis thus unmasks the true, short-ranged nature of the magnetic properties of the LiHo_xY_{1-x}F_4 system, validating recent theoretical investigations suggesting the lack of phase transition in this system.Comment: 5 pages, 4 figure

Investigation of some features of the movement of surface waves and their interaction with the surface objects´ bases and foundations providing seismic safety

В статті розглянуто особливості руху поверхневих хвиль, а також виконано аналіз існуючих методик знаходження часових характеристик та закономірностей їх зміни в процесі руху R-хвилі вздовж вільної поверхні. З цією метою були проведені розрахунки частотно-часових показників за різними формулами в R-хвилі й порівняння між собою та із значеннями в R-хвилі залежно від двох факторів: ваги заряду і приведеної відстані, результати яких висвітлено у даній роботі. Непрямим чином було встановлено, що на будь-якій епіцентральній приведеній відстані поверхнева хвиля значно більш сейсмонебезпечна, ніж об’ємна, яка на будь-яких гіпоцентральних відстанях в різних пунктів на поверхні не може перевищувати величини періоду коливань в пункті при приведеному радіусі, рівному одиниці.The article describes the features of surface waves motion as well as the analysis of existing methods for finding the timing and patterns of change in motion R-waves along the free surface. To this end, we calculated time-frequency performance under different formulas in R-wave and compared with each other and with values in R-wave dependsng on two main factors: the weight of the charge and the reduced distance, the results of which are shown in this paper. Indirectly, it was found that the at any epicentral distance surface wave is significantly seysmic unsafety than the body wave, which in any hypocentral distances at different points on the surface may not exceed the period of oscillation in the above point with raduced radius equal to one.В статье рассмотрены особенности движения поверхностных волн, а также выполнен анализ имеющихся методик нахождения временных характеристик и закономерностей их изменения в процессе движения R-волны вдоль свободной поверхности. С этой целью были проведены расчёты временно-частотных показателей по разным формулам в R-волне и сравнение между собой и с значениями в R-волне в зависимости от двух главных факторов: веса заряда и приведенного расстояния, результаты которых приведены в настоящей работе. Косвенным образом было установлено, что на любом эпицентральном приведенном расстоянии поверхностная волна значительно более сейсмоопасная, чем объемная, которая на любых гипоцентральных расстояниях в различных пунктах на поверхности не может превышать величины периода колебаний в пункте при приведенном радиусе равном 1

A new class of non-Hermitian Hamiltonians with real spectra

We construct a new class of non-Hermitian Hamiltonians with real spectra. The Hamiltonians possess one explicitly known eigenfunction.Comment: 6 page

General approach to potentials with two known levels

We present the general form of potentials with two given energy levels $E_{1}$, $E_{2}$ and find corresponding wave functions. These entities are expressed in terms of one function $\xi (x)$ and one parameter $\Delta E=E_{2}$-$E_{1}$. We show how the quantum numbers of both levels depend on properties of the function $\xi (x)$. Our approach does not need resorting to the technique of supersymmetric (SUSY) quantum mechanics but automatically generates both the potential and superpotential.Comment: 14 pages, REVTeX 3.0. In v.2 misprints and inaccuracies in presentation corrected, discussion of 3-dim. case added. In v.3 misprint in eq. 41, several typos and inaccuracies in English corrected. To be published in J. of Phys. A: Math. Ge

Вплив сезонних факторів на вміст кератоз, вільних внутрішніх ліпідів та фізичні показники вовни овець

Вовноутворення – складний та багатогранний процес, який залежить від багатьох чинників, а саме генетичних, аліментарних, умов утримання тварин, у тому числі і впливу сезонних факторів. Для дослідження використовували вовну вівцематок породи прекос, зразки якої відбирали у різні сезони року, зокрема у зимовий, весняний, літній та осінній періоди утримання тварин. Встановлено, що вміст гамма-кератози, тобто матриксу волокна, є найвищим у літній та осінній періоди, тобто періоди найкращого аліментарного забезпечення тварин. У пасовищний період у вовні овець також міститься найвища кількість вільних внутрішніх ліпідів (1,1%). У осінній період їхня кількість починає поступово зменшуватися, і найменше їх зафіксовано у зимово-стійловий період (0,9%). Найбільш чіткі сезонні зміни серед цих ліпідів зафіксовані з боку холестеролових фракцій. Зокрема, найбільша кількість неетерифікованого холестеролу міститься у вовні зимового росту – 67,2%. З настанням весни кількість цієї фракції зменшується до 62,3% (Р < 0,01), і ця тенденція продовжується у літній (61,6%, Р < 0,001) та осінній (60,8%, Р < 0,01) періоди. Щодо етерифікованого холестеролу, то тут спостерігається діаметрально протилежна картина змін. Встановлено, що міцність вовни літньо-осіннього періоду росту є більшою на 12% порівняно з вовною, яка виросла у зимово-стійловий період. Показано, що між міцністю волокон та вмістом у них церамідів існує позитивний зв’язок, який у зимовий період становив – 0,923, весняний – 0,989, літній – 0,827, осінній – 0,786.Wool formation is a complex and multifaceted process, which depend on a lot of factors, namely genetic, alimentary, animal maintenance conditions, including seasonal factors’ impact. Seasonal weather changes or so-called photoperiodism, changing the retention and feeding regimes by periods of the year, highly correlate with the physiological state of the organism of the sheep and influence the growth and quality of the wool. Given this the purpose of our work was to investigate the impact of the season on the macrostructure, chemical composition and physical properties of wool. For the research wool of ewe breed precos was used, the samples of which were taken in different seasons, in particular winter, spring, summer and autumn periods of animal maintenance. In the wool there were determined the contents of keratoses and free internal lipids, as well as the strength of the fibers at the break. It was established that wool that grew in the winter and spring period contains the largest amount of protein macro- and microfiber, i.e. alpha keratosis. Instead, with the onset of summer and until autumn the amount of this fraction decreased by an average of 2%. A similar trend was observed on the part of beta keratosis, however, these changes were less significant and did not exceed one percent. It has been established that the content of gamma keratosis, i.e. matrix of fiber, is on the highest level in summer and spring periods, that is, the periods of the best alimentary provision of animals. In the pasture period in the sheep wool there is the biggest amount of free internal lipids (1.1%). In the autumn period, their number begins to decrease gradually and the lowest one is recorded in the winter-stool period (0.9%). The most distinct seasonal changes among these lipids are fixed by cholesterol factions. In particular, the largest number of unesterified cholesterol is contained in the wool of winter growth – 67.2%. With the onset of spring the amount of this fraction decreases up to 62.3% (Р < 0.01) and the trend continues in the summer (61.6%, Р < 0.001) and autumn (60.8%, Р < 0.01) periods. Regarding unesterified cholesterol, there is a diametrically opposite picture of changes. It was established that the strength of the wool of the summer-autumn growth period is bigger by 12%, in comparison with the wool that grew in the winter-stool period. It is shown that there is a positive correlation between the strength of fibers and the content of ceramides in them, which in the winter period was 0.923, in the spring one was 0.989, for summer it was 0.827, in autumn it was 0.786

Nuclear spin driven quantum relaxation in LiY_0.998Ho_0.002F_4

Staircase hysteresis loops of the magnetization of a LiY_0.998Ho_0.002F_4 single crystal are observed at subkelvin temperatures and low field sweep rates. This behavior results from quantum dynamics at avoided level crossings of the energy spectrum of single Ho^{3+} ions in the presence of hyperfine interactions. Enhanced quantum relaxation in constant transverse fields allows the study of the relative magnitude of tunnel splittings. At faster sweep rates, non-equilibrated spin-phonon and spin-spin transitions, mediated by weak dipolar interactions, lead to magnetization oscillations and additional steps.Comment: 5 pages, 5 eps figures, using RevTe

Assessment of the reliability of the locomotive based on statistical methods of quality management

The lack of reliability of the diesel locomotive operation leads to a decrease in the technical and economic efficiency of using the locomotive service of the enterprise. During the experiment which aimed at assessing the reliability of repair and maintenance of a diesel locomotive in one of the railway divisions of OJSC "Russian Railways", it was found that the failures may be distributed by types of equipment, based on the failures for 12 months of 2017. Statistical quality management methods were used to identify the most problematic types of locomotive equipment and specific causes of failures. © Published under licence by IOP Publishing Ltd

The brachistochrone problem in open quantum systems

Recently, the quantum brachistochrone problem is discussed in the literature by using non-Hermitian Hamilton operators of different type. Here, it is demonstrated that the passage time is tunable in realistic open quantum systems due to the biorthogonality of the eigenfunctions of the non-Hermitian Hamilton operator. As an example, the numerical results obtained by Bulgakov et al. for the transmission through microwave cavities of different shape are analyzed from the point of view of the brachistochrone problem. The passage time is shortened in the crossover from the weak-coupling to the strong-coupling regime where the resonance states overlap and many branch points (exceptional points) in the complex plane exist. The effect can {\it not} be described in the framework of standard quantum mechanics with Hermitian Hamilton operator and consideration of $S$ matrix poles.Comment: 18 page

Associations of BCL-2 (RS17759659), CTLA-4 (RS231775), APO-1/FAS (RS2234767) genes polymorphisms with activity of proliferation and apoptosis in thyroid tissue of patients with nodular forms of goiter combined with autoimmune thyroiditis and thyroid adenoma

The study of apoptosis and proliferative activity in the thyroid gland (TG) tissue of patients with nodular goiter and autoimmune thyroiditis (NGAIT) and thyroid adenoma (TA) is based on the expression/density of Fas/FasL, BCL-2, p53, and Ki-67 markers assessment depending on the genetic polymorphisms of BCL-2 (rs17759659), CTLA-4 (rs231775) and APO-1/Fas (rs2234767) genes.Several mechanisms of thyroid cells' programmed killing are activated in NGAIT and TA with domination of Fas-induced apoptosis, which strongly associates with the BCL-2 gene's (rs17759659) promoter (F=25.33; p<0.001) and almost six fold weaker associates with the CTLA-4 gene's (rs231775) promoter (F=4.23, p=0.017). Factors that decrease the likelihood of NGAIT and TA regardless of the CTLA-4 (rs231775) and APO-1/Fas (rs2234767) genes' genotypes are the high Ki-67 density and reduction of cells containing p53 or BCL-2 proteins (OR=0.07-0.17; 95% CI OR: 0.03-0.36; p<0.001, and OR=0.08-0.11; 95% CI OR: 0.02-0.31; p<0.001, re­spectively). High expression of surface Fas and FasL in lymphoid infiltration and de­struction of thyroid cells (stronger in GG-genotype carriers of the BCL-2 gene by 18.54% (pAA=0.043) and 36.18% (pAG=0.018), respectively) indicates the initiation of the external pathway of apoptosis through the caspase mechanism (effector caspase- 8)