Dielectric Properties of the Quasi-Two-Dimensional Electron Liquid in Heterojunctions

A quasi-two-dimensional (Q2D) electron liquid (EL) is formed at the interface of a semiconductor heterojunction. For an accurate characterization of the Q2D EL, many-body effects need to be taken into account beyond the random phase approximation. In this theoretical work, the self-consistent static local-field correction known as STLS is applied for the analysis of the Q2D EL. The penetration of the charge distribution to the barrier-acting material is taken into consideration through a variational approach. The Coulomb from factor that describes the effective 2D interaction is rigorously treated. The longitudinal dielectric function and the plasmon dispersion of the Q2D EL are presented for a wide range of electron and ionized acceptor densities choosing GaAs/AlGaAs as the physical system. Analytical expressions fitted to our results are also supplied to enable a widespread use of these results.Comment: 39 pages (in LaTeX), including 8 PostScript figure

Label-Free Nanometer-Resolution Imaging of Biological Architectures through Surface Enhanced Raman Scattering

Label free imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with super resolution imaging. We demonst

Thermoelectric power of nondegenerate Kane semiconductors under the conditions of mutual electron-phonon drag in a high electric field

The thermoelectric power of nondegenerate Kane semiconductors with due regard for the electron and phonon heating, and their thermal and mutual drags is investigated. The electron spectrum is taken in the Kane two-band form. It is shown that the nonparabolicity of electron spectrum significantly influences the magnitude of the thermoelectric power and leads to a change of its sign and dependence on the heating electric field. The field dependence of the thermoelectric power is determined analytically under various drag conditions.Comment: 25 pages, RevTex formatted, 3 table

Microsurgery can cure most intracranial dural arteriovenous fistulae of the sinus and non-sinus type

There is consensus that intracranial dural arteriovenous fistulae (dAVF) with direct (non-sinus-type) or indirect (sinus-type) retrograde filling of a leptomeningeal vein should be treated due to the high risk of neurological deficits and hemorrhage. No consensus exists on treatment modality (surgery and/or embolization) and, if surgery is performed, on the best surgical strategy. This series aims to evaluate the role of surgery in the management of aggressive dAVFs. Forty-two patients underwent surgery. Opening and packing the sinus with thrombogenic material was performed in 9 of the 12 sinus-type dAVFs. In two sinus-type fistulae of the cavernous sinus and 1 of the torcular, microsurgery was used as prerequisite for subsequent embolization by providing access to the sinus. In the 30 non-sinus-type dAVFs, surgery consisted of interruption of the draining vein at the intradural entry point. In 41 patients undergoing 43 operations, elimination of the dAVF was achieved (97.6%). In one case, a minimal venous drainage persisted after surgery. The transient surgical morbidity was 11.9% (n = 5) and the permanent surgical morbidity 7.1% (n = 3). Our surgical strategy was to focus on the arterialized leptomeningeal vein in the non-sinus-type and on the arterialized sinus segment in the sinus-type dAVFs allowing us to obliterate all but one dAVF with a low morbidity rate. We therefore propose that microsurgery should be considered early in the treatment of both types of aggressive dAVFs. In selected cases of cavernous sinus dAVFs, the role of microsurgery is reduced to that of an adjunct to endovascular therapy

Law-governed natures of biochemical processes in permanent-teeth roots canals while children’s periodontitis

В исследовании принимали участие дети в возрасте 7 – 15 лет с обострившейся (44 человека) и хронической формой (42 человека) периодонтита, которые составили две отдельные группы. Каждая группа в свою очередь была разделена на подгруппу сравнения, детям которой проводили базовую терапию и основную, детям которой поэтапно проводили предлагаемую схему лечения периодонтита. Традиционная терапия обострившегося и хронического периодонтита в группах сравнения привела к существенному уменьшению активности уреазы и достоверному снижению лизоцима в экссудатах. После обработки корневого канала «жидкостью для лечения периодонтита» с последующим применением сорбента в основных группах активность уреазы не обнаружена при обеих формах периодонтита, уровень лизоцима увеличился в 3,9 раза, тогда как после базовой терапии в группе сравнения содержание лизоцима повысилось только в 1,8 раза. Применение предлагаемой схемы лечения хронического периодонтита привело к снижению МДА в экссудате в 30,5 раза на фоне падения этого показателя в 5,5 раза в экссудате детей после традиционной терапии в группе сравнения; и к более выраженному увеличению активности каталазы по отношению к этому показателю в группах сравнения.У дослідженні брали участь діти віком 7-15 років із загостреною (44 особи) і хронічною формою (42 особи) періодонтиту , які склали дві окремі групи. Кожна група у свою чергу була розподілена на підгрупу по рівняння, дітям якої проводили базову терапію, і основну, дітям якої поетапно проводили запропоновану схему лікування періодонтиту. Традиційна терапія загостреного і хронічного періодонтиту у групах порівняння призвело до суттєвого зменшення активності уреази та достеменного зниження лізоциму в ексудатах. Після обробки кореневого каналу «рідиною для лікування періодонтиту» з подальшим застосуванням сорбента в основних групах активність уреази не виявлена при обох формах періодонтита, рівень лізоцима збільшився у 3,9 рази, тоді як після базової терапії у групі порівняння рівень лізоцима збільшився тільки в 1,8 рази. Застосування запропонованої схеми лікування хронічного періодонтиту призвело до зниження МДА в ексудаті у 30,5 раз на фоні падіння цього показника у 5,5 раз в ексудаті дітей після традиційної терапії у групі порівняння, і більш вираженого збільшення активності каталази стосовно цього показника у групі порівняння.There were examined two separate groups of children aged 7 to 15 years (44 and 42 persons, acute and chronic periodontitis, respectively). Each group was subdivided into a reference subgroup of the children treated with the traditional periodontitis therapy, and a basic subgroup with the children subjected to step-by-step treatment with the proposed therapeutic regimen of pathology. As for the reference subgroups, the treatment of acute and chronic periodontitis with traditional therapy resulted in considerable decrease of the urease activity in exudates and in significant decrease of the lysozyme activity in exudates. As for the basic subgroups, upon the root-canal treatment with periodontal fluid followed by usage of sorbent, the level of lysozyme increased 3.9 times. As for the reference subgroup, upon the standard therapeutic treatment, the level of lysozyme increased just 1.8 times. While considering chronic periodontitis, the proposed regimen treatment resulted in 30.5-times decrease of malonic dialdehyde in exudates, and the traditional therapeutic treatment resulted in just 5.5-times decrease; besides, the former treatment, when compared with the effect in reference subgroups, resulted in higher catalase activity

Clinical and organizational factors associated with mortality during the peak of first COVID-19 wave: the global UNITE-COVID study

Purpose: To accommodate the unprecedented number of critically ill patients with pneumonia caused by coronavirus disease 2019 (COVID-19) expansion of the capacity of intensive care unit (ICU) to clinical areas not previously used for critical care was necessary. We describe the global burden of COVID-19 admissions and the clinical and organizational characteristics associated with outcomes in critically ill COVID-19 patients. Methods: Multicenter, international, point prevalence study, including adult patients with SARS-CoV-2 infection confirmed by polymerase chain reaction (PCR) and a diagnosis of COVID-19 admitted to ICU between February 15th and May 15th, 2020. Results: 4994 patients from 280 ICUs in 46 countries were included. Included ICUs increased their total capacity from 4931 to 7630 beds, deploying personnel from other areas. Overall, 1986 (39.8%) patients were admitted to surge capacity beds. Invasive ventilation at admission was present in 2325 (46.5%) patients and was required during ICU stay in 85.8% of patients. 60-day mortality was 33.9% (IQR across units: 20%–50%) and ICU mortality 32.7%. Older age, invasive mechanical ventilation, and acute kidney injury (AKI) were associated with increased mortality. These associations were also confirmed specifically in mechanically ventilated patients. Admission to surge capacity beds was not associated with mortality, even after controlling for other factors. Conclusions: ICUs responded to the increase in COVID-19 patients by increasing bed availability and staff, admitting up to 40% of patients in surge capacity beds. Although mortality in this population was high, admission to a surge capacity bed was not associated with increased mortality. Older age, invasive mechanical ventilation, and AKI were identified as the strongest predictors of mortality

Co-infection and ICU-acquired infection in COIVD-19 ICU patients: a secondary analysis of the UNITE-COVID data set

Background: The COVID-19 pandemic presented major challenges for critical care facilities worldwide. Infections which develop alongside or subsequent to viral pneumonitis are a challenge under sporadic and pandemic conditions; however, data have suggested that patterns of these differ between COVID-19 and other viral pneumonitides. This secondary analysis aimed to explore patterns of co-infection and intensive care unit-acquired infections (ICU-AI) and the relationship to use of corticosteroids in a large, international cohort of critically ill COVID-19 patients.Methods: This is a multicenter, international, observational study, including adult patients with PCR-confirmed COVID-19 diagnosis admitted to ICUs at the peak of wave one of COVID-19 (February 15th to May 15th, 2020). Data collected included investigator-assessed co-infection at ICU admission, infection acquired in ICU, infection with multi-drug resistant organisms (MDRO) and antibiotic use. Frequencies were compared by Pearson's Chi-squared and continuous variables by Mann-Whitney U test. Propensity score matching for variables associated with ICU-acquired infection was undertaken using R library MatchIT using the "full" matching method.Results: Data were available from 4994 patients. Bacterial co-infection at admission was detected in 716 patients (14%), whilst 85% of patients received antibiotics at that stage. ICU-AI developed in 2715 (54%). The most common ICU-AI was bacterial pneumonia (44% of infections), whilst 9% of patients developed fungal pneumonia; 25% of infections involved MDRO. Patients developing infections in ICU had greater antimicrobial exposure than those without such infections. Incident density (ICU-AI per 1000 ICU days) was in considerable excess of reports from pre-pandemic surveillance. Corticosteroid use was heterogenous between ICUs. In univariate analysis, 58% of patients receiving corticosteroids and 43% of those not receiving steroids developed ICU-AI. Adjusting for potential confounders in the propensity-matched cohort, 71% of patients receiving corticosteroids developed ICU-AI vs 52% of those not receiving corticosteroids. Duration of corticosteroid therapy was also associated with development of ICU-AI and infection with an MDRO.Conclusions: In patients with severe COVID-19 in the first wave, co-infection at admission to ICU was relatively rare but antibiotic use was in substantial excess to that indication. ICU-AI were common and were significantly associated with use of corticosteroids