Профессору А. А. Дульзону - 70 лет

31 июля исполнилось 70 лет со дня рождения профессора Томского политехнического университета Альфреда Андреевича Дульзона

Rolling current collector in direct current machines

The new method of rolling current collector has been developed. Its theoretical research was carried out. The operating model sample of the current collecting device using the rolling contact was made

Использование грейдинга в медиасфере

С помощью метода грейдинга разработана технология построения системы управления персоналом в медиасфере. Разработаны семь основных критериев для оценки должностей: навыки, образование, руководство, ответственность, вклад в результат (цена ошибки), коммуникационные навыки, вклад в обслуживание клиента. Предложена матрица грейдов и сетка окладов для организации. Показаны трудности внедрения системы грейдов

A Distributed Heterostructure Barrier Varactor Frequency Tripler

We present a broadband nonlinear transmission line (NLTL) frequency multiplier at F-band. The multiplier consists of a finline section periodically loaded with 15 heterostructure barrier varactor (HBV) diodes. Tapered slot antennas are used to couple the fundamental signal from a WR-22 rectangular waveguide to the distributed multiplier as well as radiate the output power into free space. The frequency tripler exhibits 10-dBm peak radiated power at 130.5 GHz with more than 10% 3-dB bandwidth and 7% conversion efficiency. The tripler can be used as an inexpensive broad-band solid-state source for millimeter-wave applications

Heterostructure-Barrier-Varactor Design

In this paper, we propose a simple set of accurate frequency-domain design equations for calculation of optimum embedding impedances, optimum input power, bandwidth, and conversion efficiency of heterostructure-barrier-varactor (HBV) frequency triplers. A set of modeling equations for harmonic balance simulations of HBV multipliers are also given. A 141-GHz quasi-optical HBV tripler was designed using the method and experimental results show good agreement with the predicted results

Recent wind driven high sea ice area export in the Fram Strait contributes to Arctic sea ice decline

Arctic sea ice area has been decreasing for the past two decades. Apart from melting, the southward drift through Fram Strait is the main ice loss mechanism. We present high resolution sea ice drift data across 79° N from 2004 to 2010. Ice drift has been derived from radar satellite data and corresponds well with variability in local geostrophic wind. The underlying East Greenland current contributes with a constant southward speed close to 5 cm s−1, and drives around a third of the ice export. We use geostrophic winds derived from reanalysis data to calculate the Fram Strait ice area export back to 1957, finding that the sea ice area export recently is about 25% larger than during the 1960's. The increase in ice export occurred mostly during winter and is directly connected to higher southward ice drift velocities, due to stronger geostrophic winds. The increase in ice drift is large enough to counteract a decrease in ice concentration of the exported sea ice. Using storm tracking we link changes in geostrophic winds to more intense Nordic Sea low pressure systems. Annual sea ice area export likely has a significant influence on the summer sea ice variability and we find low values in the 1960's, the late 1980's and 1990's, and particularly high values during 2005–2008. The study highlights the possible role of variability in ice export as an explanatory factor for understanding the dramatic loss of Arctic sea ice during the last decadespublishedVersio

Sr and Nd isotope data for arc-related (meta) volcanics (SW Iberia)

In the southern sector of the Ossa-Morena Zone (Iberian Variscan Chain), along its boundaries with the Beja-Acebuches Ophiolite and the South-Portuguese Zone, Upper Palaeozoic igneous mafic and intermediate rocks, both intrusive and extrusive, are widely represented. The so-called Odivelas Unit (Andrade,1983), include (meta-) basalts and (meta-) andesites, which, according with previous studies, display low-K tholeiitic to calc-alkaline signatures and, therefore, are interpreted as remnants of an active margin volcanic arc. Santos et al. (1990) subdivided those volcanics into two groups: in Alfundão-Peroguarda, the tholeiitic nature is dominant; in Odivelas-Penique, the calc-alkaline signature becomes more pronounced. Intercalation of limestone layers provided some age constraints, showing that the subduction-related volcanic activity in the studied area began in the Lower Devonian and continued, at least, through the Middle Devonian (Conde & Andrade, 1974; Machado et al., 2010). In this work, samples previously studied by Santos et al. (1990) and Silva et al. (2011) were analysed for Sm-Nd and Rb-Sr isotopes. Considering that the volcanics were systematically affected by hydrothermal metamorphism, it is expected that the Sr signatures show significant disturbance. In contrast, Nd isotope ratios probably reflect the primary features. Alfundão-Peroguarda samples show a very limited range of positive initial εNd, from +5.1 to +4.3 (assuming 400 Ma), showing no evidence for significant crustal assimilation and, therefore, allowing the attribution of negative Nb and Ta anomalies to arc-related processes On the other hand, 87Sr/86Sr varies from 0.7044 to 0.7060 (for 400Ma). These samples rocks define a horizontal trend on the initial εNd vs. initial 87Sr/86Sr plot, typical of co-genetic rocks that underwent interaction with seawater. On the other hand, Odivelas-Penique volcanics show wide spectra for both initial 87Sr/86Sr (from 0.7038 to 0.7066) and εNd (from +4.6 to -4.1). Significantly, the highest εNd values for this group are within the narrow range defined by Alfundão-Peroguarda tholeiitic basalts, suggesting a common mantle source (or very similar sources) for the most mafic magmas of both sectors. The whole set of Nd isotope ratios supports the distinction previously proposed between the two groups of volcanics. In addition, the variation from positive to negative initial εNd values in the Odivelas-Penique suite shows that its geochemical features were likely influenced by assimilation of continental crustal material

Magnetic Resonance Spectroscopy in Depressed Subjects Treated With Electroconvulsive Therapy—A Systematic Review of Literature

Electroconvulsive therapy (ECT) is considered to be the most effective acute treatment for otherwise treatment resistant major depressive episodes, and has been used for over 80 years. Still, the underlying mechanism of action is largely unknow. Several studies suggest that ECT affects the cerebral neurotransmitters, such as gamma-aminobutyric acid (GABA) and glutamate. Magnetic resonance spectroscopy (MRS) allows investigators to study neurotransmitters in vivo, and has been used to study neurochemical changes in the brain of patients treated with ECT. Several investigations have been performed on ECT-patients; however, no systematic review has yet summarized these findings. A systematic literature search based on the Prisma guidelines was performed. PubMed (Medline) was used in order to find investigations studying patients that had been treated with ECT and had undergone an MRS examination. A search in the databases Embase, PsycInfo, and Web of Science was also performed, leading to no additional records. A total of 30 records were identified and screened which resulted in 16 original investigations for review. The total number of patients that was included in these studies, ignoring potential overlap of samples in some investigations, was 325. The metabolites reported were N-acetyl aspartate, Choline, Myoinositol, Glutamate and Glutamine, GABA and Creatine. The strongest evidence for neurochemical change related to ECT, was found for N-acetyl aspartate (reduction), which is a marker of neuronal integrity. Increased choline and glutamate following treatment was also commonly reported.publishedVersio

6 min walk test is a strong independent predictor of death in outpatients with heart failure

Aims The aim of this study was to examine the prognostic value of the 6 min walk test (6MWT) in a large cohort of outpatients with heart failure. Methods and results A total of 5519 outpatients with heart failure from the National Norwegian Heart Failure Registry (NNHFR), which is part of the Norwegian Cardiovascular Disease Registry, were included in this analysis. The NNHFR recommended the use of the 6MWT for prognostic assessment of all patients included in the registry. Patients were categorized according to the 6MWT: Category 1 walked the longest and Category 3 the shortest. During a median (25th–75th percentiles) follow-up of 24 (14–36), 12.9% of the patients died. Patients in Category 3 had the overall worst outcome than had patients in Categories 1 and 2. 6MWT used as a continuous variable was a highly significant independent predictor for mortality in a multivariate Cox regression model adjusted for 16 other variables with a hazard ratio of 0.979 [(95% confidence interval 0.972–0.986), P < 0.001]. The four most important predictors for mortality were active cancer in the last 5 years, age, 6MWT, and natriuretic peptides (all P < 0.001). Conclusions 6MWT is a strong independent predictor of mortality in outpatients with HF. The findings support the use of the 6MWT in the prognostic assessment of patients with HF irrespective of HF aetiology.publishedVersio