Suppression of hole-hole scattering in GaAs/AlGaAs heterostructures under uniaxial compression

Resistance, magnetoresistance and their temperature dependencies have been investigated in the 2D hole gas at a [001] p-GaAs/Al$_{0.5}$Ga$_{0.5}$As heterointerface under [110] uniaxial compression. Analysis performed in the frame of hole-hole scattering between carriers in the two spin splitted subbands of the ground heavy hole state indicates, that h-h scattering is strongly suppressed by uniaxial compression. The decay time $\tau_{01}$ of the relative momentum reveals 4.5 times increase at a uniaxial compression of 1.3 kbar.Comment: 5 pages, 3 figures. submitted to Phys.Rev.

Longitudinal Momentum Fraction X_L for Two High P_t Protons in pp->ppX Reaction

We present an analysis of new data from Experiment E850 at BNL. We have characterized the inclusive cross section near the endpoint for pp exclusive scattering in Hydrogen and in Carbon with incident beam energy of 6 GeV. We select events with a pair of back-to-back hadrons at large transverse momentum. These cross sections are parameterized with a form $\frac{d \sigma}{d X_{L}}$ $\sim(1-X_{L})^{p}$, where ${X_{L}}$ is the ratio of the longitudinal momentum of the observed pair to the total incident beam momentum. Small value of $p$ may suggest that the number of partons participating in the reaction is large and reaction has a strong dependence on the center-of-mass energy. We also discuss nuclear effects observed in our kinematic region.Comment: 4 pages, 2 figures, to be published in Proceedings of CIPANP2000, Quebec, May 22-28, 2000, requires aipproc.sty(included

Energy Dependence of Nuclear Transparency in C(p,2p) Scattering

The transparency of carbon for (p,2p) quasi-elastic events was measured at beam energies ranging from 6 to 14.5 GeV at 90 degrees c.m. The four momentum transfer squared q*q ranged from 4.8 to 16.9 (GeV/c)**2. We present the observed energy dependence of the ratio of the carbon to hydrogen cross sections. We also apply a model for the nuclear momentum distribution of carbon to normalize this transparency ratio. We find a sharp rise in transparency as the beam energy is increased to 9 GeV and a reduction to approximately the Glauber level at higher energies.Comment: 4 pages, 2figures, submitted to PR

Эволюция донорства печени в Москве. Движение в направлении расширенных критериев донорства

The objective of the study was to investigate the evolution and trends in liver donation in the city of Moscow, with special focus on the expansion of liver donor selection criteria for transplantation. Materials and methods. The study included 1,548 effective donors (EDs) in the period from January 1, 2012 to December 31, 2020. Their basic characteristics – age and cause of death – are presented. The dynamics of changes in the age groups of donors and the dynamics of the number of ≥60-year-old liver donors were studied. The influence of expanded liver donor selection criteria over the dynamics of the number of transplant surgeries and patient flow on the waiting list was assessed. Results. During the study period, the number of effective liver donors (ELDs) in Moscow increased 4.7-fold. The average age of ELDs increased from 37.1 in 2012 to 48.8 in 2020. There was an absolute prevalence of donors who died from cerebrovascular accident compared with donors who died from traumatic causes, 83.4% vs 16.6%, respectively. Since 2016, there has been a progressive increase in ≥60-year-old liver donors; the number of such donors in 2020 reached 39, accounting for 13.6% of the total pool of EDs. The progressive growth in the number of liver transplants has significantly influenced patient movement on the waiting list. In 2012, there was a 25.2% increase in the number of liver transplants per 100 patients on the waiting list; by 2020, it had reached 86.6%. Conclusion. The results reasonably indicate an increase in liver donation and liver transplantation (LTx) in Moscow. Comparison of Russian data with those of leading foreign donor programs shows that the trends in the donor pool in the context of older age, including ≥60-year-old donors, and shifting causes of donor death towards cerebrovascular diseases are similar. An overall increase in donor activity and expansion of liver donor criteria contributed to an increase in the number of transplants performed per 100 patients on the waiting list, which, in turn, reduced the waiting time for a donor organ and increased the intensity of patient flow on the waiting list.Цель исследования – изучить эволюцию и тренды развития донорства печени в городе Москве, уделив особое внимание расширению критериев селекции доноров печени для трансплантации. Материалы и методы. В исследование включены 1548 эффективных доноров в период с 1 января 2012-го по 31 декабря 2020 года. Представлены их базовые характеристики – возраст, причина смерти. Изучены динамика изменения возрастных групп доноров и динамика числа доноров печени в возрасте 60 лет и старше. Оценено влияние расширения критериев селекции доноров печени на динамику числа трансплантаций и движения пациентов в листе ожидания. Результаты. За исследуемый период выявлен рост числа эффективных доноров печени в Москве в 4,7 раза. Средний возраст эффективных доноров печени увеличился с 37,1 в 2012 г. до 48,8 в 2020 г. Отмечается абсолютное преобладание доноров, умерших вследствие нарушения мозгового кровообращения, относительно доноров, умерших вследствие травматических причин, 83,4% vs 16,6% соответственно. С 2016 г. наблюдается прогрессивный рост доноров печени 60 лет и старше; в 2020 г. число таких доноров достигло 39 человек, что составило 13,6% от общего пула эффективных доноров. Прогрессивный рост количества трансплантаций печени значительно повлиял на движение пациентов в листе ожидания. В 2012 г. показатель числа трансплантаций печени на 100 пациентов из листа ожидания составлял 25,2%, к 2020 г. его рост достиг значения 86,6%. Заключение. Результаты обоснованно свидетельствуют о росте донорства и трансплантации печени в Москве. Сопоставление отечественных данных с ведущими зарубежными донорскими программами показывает, что тренды изменения донорского пула в контексте повышения возраста, включая доноров 60 лет и старше, смещения причин смерти доноров в сторону сосудистых заболеваний мозга аналогичны. Общее повышение донорской активности и расширение критериев доноров печени способствовали повышению показателя числа трансплантаций, выполняемых на 100 пациентов из листа ожидания, что, в свою очередь, вызвало снижение сроков ожидания донорского органа и повысило интенсивность движения пациентов в листе ожидания