Time-Resolved Photoluminescence in Antimonide and Dilute Nitride Quantum Well Structures

This Master's thesis is devoted to semiconductor samples study using time-resolved photoluminescence. This method allows investigating recombination in semiconductor samples in order to develop quality of optoelectronic device. An additional goal was the method accommodation for low-energy-gap materials. The first chapter gives a brief intercourse into the basis of semiconductor physics. The key features of the investigated structures are noted. The usage area of the results covers saturable semiconductor absorber mirrors, disk lasers and vertical-external-cavity surface-emittinglasers. The experiment set-up is described in the second chapter. It is based on up-conversion procedure using a nonlinear crystal and involving the photoluminescent emission and the gate pulses. The limitation of the method was estimated. The first series of studied samples were grown at various temperatures and they suffered rapid thermal annealing. Further, a latticematched and metamorphically grown samples were compared. Time-resolved photoluminescence method was adapted for wavelengths up to 1.5 µm. The results allowed to specify the optimal substrate temperature for MBE process. It was found that the lattice-matched sample and the metamorphically grown sample had similar characteristics

A nontrivial interplay between triadic closure, preferential, and anti-preferential attachment: New insights from online data

This paper presents an analysis of a temporal network that describes the social connections of a large-scale (∼30,000) sample of online social network users, inhabitants of a fixed city. We tested how the main network formation determinants—transitivity, preferential attachment, and social selection—contribute to network evolution. We obtained that tie appearing and tie removing events are governed by different combinations of mechanisms: whereas the structure of the network is responsible for the formation of new ties, nodal nonstructural characteristics “decide” whether a tie will continue to exist. Next, our findings show that only one network formation mechanism, gender selectivity, has a significant impact on both tie appearing and tie removing processes. What is interesting, the effect of gender selectivity is most notable for low-degree vertices. Besides this, our analysis revealed that opinion selectivity appears to be a noticeable (but not very important) factor only in the case of tie removing, whereas its contribution to tie appearing is elusive. Our findings suggest that nodes’ activity is a crucial factor of network evolution—the majority of tie removing events can be explained by the age-based activity mechanism. Finally, we report that transitivity and preferential attachment do govern network evolution. However, there are two important details: (i) their zone of influence is restricted primarily by tie appearing and (ii) the preferential attachment mechanism is replaced by the anti-preferential attachment rule if the number of common peers is greater than zero

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Simulation of stresses and contact surfaces of disk rolling cutters with the rock when sinking in mixed soils

In this paper, we consider the crack propagation in the rocks during sinking depending on the distance between the cutters. Under the same conditions, the hard and soft rocks form various fracture networks that leads to uneven sinking and decrease in the efficiency of the tunneling machine. In order to study this issue, four ranges of distance between the contact surfaces and various incidence angles of the contact surface were selected. The study includes a system that is a mountain mass layout with a disk cutter the only parameter of which is the tip width or the contact width of the disk cutter with the end-type rock. Simulation of research conditions and finding a solution to the problem were performed using the Autodesk Inventor Nastran 3D simulation software.</jats:p

Mathematical and Computer Simulation of the Biological Life Support System Module 1/2. Description of the model

The mathematical model based on kinetic coefficients and dependencies obtained during the experiments was constructed to estimate the character of functioning of the experimental module of biological life support system (BLSS) and the possibilities of its controlling. The mathematical model consists of two compartments - the phytotron model (with wheat and radish) and the mycotron model (for mushrooms). The following components are included into the model: edible mushrooms (mushroom fruit bodies and mycelium); wheat; radish; straw (processed by mycelium); dead organic matter in the phytotron (separately for the wheat unit and for the radish unit); worms; worms` coprolites; vermicompost used as a soil-like substrate (SLS); bacterial microflora; mineral nitrogen, phosphorus and iron; products of the system intended for humans (wheat grains, radish roots and mushroom fruit bodies); oxygen and carbon dioxide. At continuous gas exchange, the mass exchange between the compartments occurs at the harvesting time. The conveyor character of the closed ecosystem functioning has been taken into account - the number of culture age groups can be controlled (in experiments and in the model - 4 and 8 age groups). The conveyor cycle duration can be regulated as well. The module was designed for the food and gas exchange requirements of 1\30 of a virtually present human. The model estimates the values of all dynamic components of the system under various conditions and modes of functioning, especially those, which are difficult to be realized in the experiment. The model allows dynamic calculation of biotic turnover closedness coefficient for main considered elements. The coefficient of matter biotic cycle closure for systems based on matter supplies has been formalized.Для оценки характера функционирования экспериментального модуля биологической системы жизнеобеспечения и возможности управления им построена математическая модель, опирающаяся на кинетические коэффициенты и зависимости, полученные в экспериментальных исследованиях. Математическая модель состоит из двух компартментов - моделей «фитотрона» (с пшеницей и с редисом) и модели «микотрона» (для грибов). В модель включены следующие компоненты: пшеница, редис, солома (перерабатываемая мицелием), мертвое органическое вещество в фитотроне, съедобные грибы (плодовые тела и мицелий), черви, продукты жизнедеятельности червей (копролиты), вермикомпост, использующийся как почвоподобный субстрат, бактериальная микрофлора, минеральные формы биогенных элементов (азот, фосфор, железо), продукция системы для человека (зерно пшеницы, корнеплоды редиса, плодовые тела грибов), кислород и углекислый газ. При постоянном газообмене массообмен между компартментами происходит только во время снятия урожая. Учитывается конвейерный характер функционирования замкнутой экосистемы - число возрастов культуры может регулироваться (в эксперименте - четыре и восемь возрастов). Также поддается регулированию длина конвейерного цикла. По пище и газообмену модуль рассчитан на условное присутствие 1/30 доли человека. Модель позволяет оценить значения всех учитываемых динамических компонентов системы при различных условиях и режимах ее функционирования, в частности, при труднореализуемых в эксперименте условиях. Формализован коэффициент замкнутости биотического круговорота вещества для систем на запасах вещества

A Wenlockian (Silurian) gastropod shell and operculum from Siberia

In a large collection of Wenlockian gastropods from north Siberia, a single small specimen shows the operculum in situ just within the aperture. In other morphologic features, particularly the presence of numerous spiral lirae on the shell, this species is similar to Silurian gastropods traditionally assigned to Oriostoma. Preservation of the operculum is far from perfect, but almost certainly it has paucispiral growth, rather than concentric or multispiral construction. This new species (Australonema varvarae n. sp.) is assigned to Australonema, previously known only from the Lower Devonian of Australia, primarily because of the form of the operculum. The material was obtained from just below a biostromal unit in a bed interpreted as an interreef lagoon in an area of locally relatively quiet water.</jats:p

Diffusion Patterns of Social Network Posts

Social network posts as an efficient means of communication directly reflect users’ interests and engagements. Despite challenges there are strong interests in understanding how social network posts efficiently spread information. In this article some diffusion patterns of social network posts are explored. The information spreading via post chains based on partial data of popular social network is studied to gain insights of the problem of information diffusion. Mathematical models for information cascades are proposed and future research directions are discussed

Simulation of stresses and contact surfaces of disk rolling cutters with the rock when sinking in mixed soils

In this paper, we consider the crack propagation in the rocks during sinking depending on the distance between the cutters. Under the same conditions, the hard and soft rocks form various fracture networks that leads to uneven sinking and decrease in the efficiency of the tunneling machine. In order to study this issue, four ranges of distance between the contact surfaces and various incidence angles of the contact surface were selected. The study includes a system that is a mountain mass layout with a disk cutter the only parameter of which is the tip width or the contact width of the disk cutter with the end-type rock. Simulation of research conditions and finding a solution to the problem were performed using the Autodesk Inventor Nastran 3D simulation software