Conceptual aspects of line tensions

We analyze two representative systems containing a three-phase-contact line: a liquid lens at a fluid--fluid interface and a liquid drop in contact with a gas phase residing on a solid substrate. We discuss to which extent the decomposition of the grand canonical free energy of such systems into volume, surface, and line contributions is unique in spite of the freedom one has in positioning the Gibbs dividing interfaces. In the case of a lens it is found that the line tension is independent of arbitrary choices of the Gibbs dividing interfaces. In the case of a drop, however, one arrives at two different possible definitions of the line tension. One of them corresponds seamlessly to that applicable to the lens. The line tension defined this way turns out to be independent of choices of the Gibbs dividing interfaces. In the case of the second definition,however, the line tension does depend on the choice of the Gibbs dividing interfaces. We provide equations for the equilibrium contact angles which are form-invariant with respect to notional shifts of dividing interfaces which only change the description of the system. Conceptual consistency requires to introduce additional stiffness constants attributed to the line. We show how these constants transform as a function of the relative displacements of the dividing interfaces. The dependences of the contact angles on lens or drop volumes do not render the line tension alone but a combination of the line tension, the Tolman length, and the stiffness constants of the line.Comment: 34 pages, 9 figure

Enhancement of the superconducting transition temperature in Nb/Permalloy bilayers by controlling the domain state of the ferromagnet

In (S/F) hybrids the suppression of superconductivity by the exchange field h_ex of the ferromagnet can be partially lifted when different directions of h_ex are sampled simultaneously by the Cooper pair. In F/S/F trilayer geometries where the magnetization directions of the two F-layers can be controlled separately, this leads to the so-called spin switch. Here we show that domain walls in a single F-layer yield a similar effect. We study the transport properties of Ni_0.8Fe_0.2/Nb bilayers structured in strips of different sizes. For large samples a clear enhancement of superconductivity takes place in the resistive transition, in the very narrow field range (order of 0.5 mT) where the magnetization of the Py layer switches and many domains are present. This effect is absent in microstructured samples. Comparison of domain wall width \delta_w to the temperature dependent superconductor coherence length \xi_S(T) shows that \delta_w ~ \xi_S(T), which means that the Cooper pairs sample a large range of different magnetization directions.Comment: 4 pages, 5 figure

A Large-Scale FPGA-Based Trigger and Dead-Time Free DAQ System for the Kaos Spectrometer at MAMI

The Kaos spectrometer is maintained by the A1 collaboration at the Mainz Microtron MAMI with a focus on the study of (e,e'K^+) coincidence reactions. For its electron-arm two vertical planes of fiber arrays, each comprising approximately 10 000 fibers, are operated close to zero degree scattering angle and in close proximity to the electron beam. A nearly dead-time free DAQ system to acquire timing and tracking information has been installed for this spectrometer arm. The signals of 144 multi-anode photomultipliers are collected by 96-channel front-end boards, digitized by double-threshold discriminators and the signal time is picked up by state-of-the-art F1 time-to-digital converter chips. In order to minimize background rates a sophisticated trigger logic was implemented in newly developed Vuprom modules. The trigger performs noise suppression, signal cluster finding, particle tracking, and coincidence timing, and can be expanded for kinematical matching (e'K^+) coincidences. The full system was designed to process more than 4 000 read-out channels and to cope with the high electron flux in the spectrometer and the high count rate requirement of the detectors. It was successfully in-beam tested at MAMI in 2009.Comment: Contributed to 17th IEEE Real Time Conference (RT10), Lisbon, 24-28 May 201

Health status assessment of related kidney donors in the late postoperative period

ДОНОРОВ МЕДИЦИНСКИЙ ОТБОРДОНОРОВ СКРИНИНГДОНОРЫ ТКАНЕЙДОНОРЫ ОРГАНОВНЕФРЭКТОМИЯПОЧЕК ТРАНСПЛАНТАЦИЯПЕРЕСАДКА ПОЧКИПОЧЕЧНАЯ ТРАНСПЛАНТАЦИЯТРАНСПЛАНТАЦИОННАЯ ТОЛЕРАНТНОСТЬПОЧЕЧНАЯ НЕДОСТАТОЧНОСТЬПОЧКИ, НЕДОСТАТОЧНОСТЬ ФУНКЦИИПОСЛЕОПЕРАЦИОННЫЙ ПЕРИОДЦель. Изучить состояние здоровья живых доноров почки на основании степени восстановления функции почки и общего физического статуса донора. Материал и методы. 37 родственных доноров почек перенесли нефрэктомию в период с 2014 по 2017 год. Средний возраст составил 48,3±9,7 года (М±сигма), мужчин было 19 (51%), женщин – 18 (49%). В позднем послеоперационном периоде (1,9±1,1 года (М±сигма)) изучали уровни протеинурии и скорости клубочковой фильтрации (СКФ). Качество жизни доноров почек оценивали с помощью опросника Medical Outcomes Study-Short Form-36. Результаты. Средняя СКФ до операции составила 78,9±24,5 мл/мин на 1,73 м{2} и снизилась до 49,8±11,2 мл/мин на 1,73 м{2} на 2-е сутки после операции. При выписке (15,2±7,0 LYZ) средняя СКФ увеличивалась до 53,4±8,0 мл/мин на 1,73 м{2} и практически достигла предоперационного уровня через 1,9±1,1 года. Отмечено повышение креатинина и увеличение протеинурии в ранние сроки с нормализацией этих показателей в отдаленные сроки. Это свидетельствует о том, что единственная почка с нормальной функцией способна компенсировать отсутствие контралатеральной. Кроме того, наше исследование показало, что в позднем послеоперационном периоде не было статистически значимой разницы ни по СКФ, ни по качеству жизни между донорами разных возрастных групп. Таким образом, при адекватной селекции пары донор-реципиент на основе комплексного обследования, трансплантация почки является не только эффективным методом лечения терминальной стадии хронической почечной недостаточности, но и безопасна для здоровья и дальнейшей почечной функции донора. Заключение. У прижизненных доноров отмечается постепенное восстановление почечной функции, согласно СКФ, при выписке (день 15,2±7,0) и в позднем послеоперационном периоде (1,9±1,1 года) практически до предоперационного уровня. Физический и психологический компоненты здоровья доноров разных возрастных групп были сопоставимы.Objective. To analyze the health status of living kidney donors based on the degree of restoration of the kidney function and the general physical status of the donor. Methods. 37 related kidney donors underwent nephrectomy between 2014 and 2017. The average age was 48.3±9.7 (М±sigma) years, with 19 men (51%) and 18 (49%) women. In the late postoperative period (1,9±1,1 years (М±sigma), the levels of proteinuria, and glomerular filtration rate (GFR) were studied. The life quality of kidney donors was assessed using the Medical Outcomes Study-Short Form-36 questionnaire. Results. The average GFR before the operation was 78,9±24,5 ml/min per 1.73 m{2}, and fell to 49,8±11,2 ml/min per 1.73 m{2} on the 2nd day after the operation. Upon discharge (15,2±7,0 day), average GFR increased to 53,4±8,0 ml/min per 1.73 m{2}, and almost reached pre-operation levels 1,9±1,1 years after the operation. This suggests that a single normally-functioning kidney is capable of taking on the load from the missing kidney. Furthermore, our study showed that, in the late postoperative period, there was no statistically significant difference in either GFR or quality of life between the donors of different age groups (p>0.05). Our research showed that if adequate protocols are used for living donor selection, donor-recipient kidney transplantation is not only an effective method for treating terminal stage of chronic end stage of renal disease, but is also safe for health and the subsequent renal function of the donor. Conclusions. In living donors, a gradual restoration of renal function is observed, according to GFR, at discharge (day 15.2±7.0) and in the late postoperative period (1.9±1.1 years), almost reaching the preoperative level. The physical and psychological health components of donors of different age groups were comparable

Experimental evidence for the separability of compound-nucleus and fragment properties in fission

The large body of experimental data on nuclear fission is analyzed with a semi-empirical ordering scheme based on the macro-microscopic approach and the separability of compound-nucleus and fragment properties on the fission path. We apply the statistical model to the non-equilibrium descent from saddle to scission, taking the influence of dynamics into account by an early freeze out. The present approach reveals a large portion of common features behind the variety of the complex observations made for the different systems. General implications for out-of-equilibrium processes are mentioned.Comment: 11 pages, 3 figure

Observation of the Triplet Spin-Valve Effect in a Superconductor-Ferromagnet Heterostructure

The theory of superconductor-ferromagnet (S-F) heterostructures with two ferromagnetic layers predicts the generation of a long-range, odd-in-frequency triplet pairing at non-collinear alignment (NCA) of the magnetizations of the F-layers. This triplet pairing has been detected in a Nb/Cu41Ni59/nc-Nb/Co/CoOx spin-valve type proximity effect heterostructure, in which a very thin Nb film between the F-layers serves as a normal conducting (nc) spacer. The resistance of the sample as a function of an external magnetic field shows that for not too high fields the system is superconducting at a collinear alignment of the Cu41Ni59 and Co layer magnetic moments, but switches to the normal conducting state at a NCA configuration. This indicates that the superconducting transition temperature Tc for NCA is lower than the fixed measuring temperature. The existence of a minimum Tc, at the NCA regime below that one for parallel or antiparallel alignments of the F-layer magnetic moments, is consistent with the theoretical prediction of a singlet superconductivity suppression by the long-range triplet pairing generation.Comment: 7 pages, 4 fgures, Submitted to Physical Review Letter

Transition Radiation Spectra of Electrons from 1 to 10 GeV/c in Regular and Irregular Radiators

We present measurements of the spectral distribution of transition radiation generated by electrons of momentum 1 to 10 GeV/c in different radiator types. We investigate periodic foil radiators and irregular foam and fiber materials. The transition radiation photons are detected by prototypes of the drift chambers to be used in the Transition Radiation Detector (TRD) of the ALICE experiment at CERN, which are filled with a Xe, CO2 (15 %) mixture. The measurements are compared to simulations in order to enhance the quantitative understanding of transition radiation production, in particular the momentum dependence of the transition radiation yield.Comment: 18 pages, 15 figures, submitted to Nucl. Instr. Meth. Phys. Res.

Transition Radiation Spectroscopy with Prototypes of the ALICE TRD

We present measurements of the transition radiation (TR) spectrum produced in an irregular radiator at different electron momenta. The data are compared to simulations of TR from a regular radiator.Comment: 4 pages, 5 Figures, Proceedings for "TRDs for the 3rd millennium" (Sept. 4-7, 2003, Bari, Italy

Energy loss of pions and electrons of 1 to 6 GeV/c in drift chambers operated with Xe,CO2(15%)

We present measurements of the energy loss of pions and electrons in drift chambers operated with a Xe,CO2(15%) mixture. The measurements are carried out for particle momenta from 1 to 6 GeV/c using prototype drift chambers for the ALICE TRD. Microscopic calculations are performed using input parameters calculated with GEANT3. These calculations reproduce well the measured average and most probable values for pions, but a higher Fermi plateau is required in order to reproduce our electron data. The widths of the measured distributions are smaller for data compared to the calculations. The electron/pion identification performance using the energy loss is also presented.Comment: 15 pages, 10 figures, accepted for publication in Nucl.Instrum.Meth.

Space charge in drift chambers operated with the Xe,CO2(15%) mixture

Using prototype modules of the ALICE Transition Radiation Detector we investigate space charge effects and the dependence of the pion rejection performance on the incident angle of the ionizing particle. The average pulse height distributions in the drift chambers operated with the Xe,CO2(15%) mixture provide quantitative information on the gas gain reduction due to space charge accumulating during the drift of the primary ionization. Our results demonstrate that the pion rejection performance of a TRD is better for tracks which are not at normal incidence to the anode wires. We present detailed simulations of detector signals, which reproduce the measurements and lend strong support to our interpretation of the measurements in terms of space charge effects.Comment: 18 pages, 10 figures, accepted for publication in Nucl.Instrum.Meth. A. Data files available at http://www-alice.gsi.de/tr