Shielding of a small charged particle in weakly ionized plasmas

In this paper we present a concise overview of our recent results concerning the electric potential distribution around a small charged particle in weakly ionized plasmas. A number of different effects which influence plasma screening properties are considered. Some consequences of the results are discussed, mostly in the context of complex (dusty) plasmas.Comment: This is a short review pape

On the convergence of stresses in fretting fatigue

Fretting is a phenomenon that occurs at the contacts of surfaces that are subjected to oscillatory relative movement of small amplitudes. Depending on service conditions, fretting may significantly reduce the service life of a component due to fretting fatigue. In this regard, the analysis of stresses at contact is of great importance for predicting the lifetime of components. However, due to the complexity of the fretting phenomenon, analytical solutions are available for very selective situations and finite element (FE) analysis has become an attractive tool to evaluate stresses and to study fretting problems. Recent laboratory studies in fretting fatigue suggested the presence of stress singularities in the stick-slip zone. In this paper, we constructed finite element models, with different element sizes, in order to verify the existence of stress singularity under fretting conditions. Based on our results, we did not find any singularity for the considered loading conditions and coefficients of friction. Since no singularity was found, the present paper also provides some comments regarding the convergence rate. Our analyses showed that the convergence rate in stress components depends on coefficient of friction, implying that this rate also depends on the loading condition. It was also observed that errors can be relatively high for cases with a high coefficient of friction, suggesting the importance of mesh refinement in these situations. Although the accuracy of the FE analysis is very important for satisfactory predictions, most of the studies in the literature rarely provide information regarding the level of error in simulations. Thus, some recommendations of mesh sizes for those who wish to perform FE analysis of fretting problems are provided for different levels of accuracy

Comprehensive analysis of normal adjacent to tumor transcriptomes.

Histologically normal tissue adjacent to the tumor (NAT) is commonly used as a control in cancer studies. However, little is known about the transcriptomic profile of NAT, how it is influenced by the tumor, and how the profile compares with non-tumor-bearing tissues. Here, we integrate data from the Genotype-Tissue Expression project and The Cancer Genome Atlas to comprehensively analyze the transcriptomes of healthy, NAT, and tumor tissues in 6506 samples across eight tissues and corresponding tumor types. Our analysis shows that NAT presents a unique intermediate state between healthy and tumor. Differential gene expression and protein-protein interaction analyses reveal altered pathways shared among NATs across tissue types. We characterize a set of 18 genes that are specifically activated in NATs. By applying pathway and tissue composition analyses, we suggest a pan-cancer mechanism of pro-inflammatory signals from the tumor stimulates an inflammatory response in the adjacent endothelium

ZnO Coatings with Controlled Pore Size, Crystallinity and Electrical Conductivity

Zinc oxide is a wide bandgap semiconductor with unique optical, electrical and catalytic properties. Many of its practical applications rely on the materials pore structure, crystallinity and electrical conductivity. We report a synthesis method for ZnO films with ordered mesopore structure and tuneable crystallinity and electrical conductivity. The synthesis relies on dip-coating of solutions containing micelles of an amphiphilic block copolymer and complexes of Zn2+ ions with aliphatic ligands. A subsequent calcination at 400 °C removes the template and induces crystallization of the pore walls. The pore structure is controlled by the template polymer, whereas the aliphatic ligands control the crystallinity of the pore walls. Complexes with a higher thermal stability result in ZnO films with a higher content of residual carbon, smaller ZnO crystals and therefore lower electrical conductivity. The paper discusses the ability of different types of ligands to assist in the synthesis of mesoporous ZnO and relates the structure and thermal stability of the precursor complexes to the crystallinity and electrical conductivity of the zinc oxide

3D structure of Thermus aquaticus single-stranded DNA–binding protein gives insight into the functioning of SSB proteins

In contrast to the majority of tetrameric SSB proteins, the recently discovered SSB proteins from the Thermus/Deinoccus group form dimers. We solved the crystal structures of the SSB protein from Thermus aquaticus (TaqSSB) and a deletion mutant of the protein and show the structure of their ssDNA binding domains to be similar to the structure of tetrameric SSBs. Two conformations accompanied by proline cis–trans isomerization are observed in the flexible C-terminal region. For the first time, we were able to trace 6 out of 10 amino acids at the C-terminus of an SSB protein. This highly conserved region is essential for interaction with other proteins and we show it to adopt an extended conformation devoid of secondary structure. A model for binding this region to the χ subunit of DNA polymerase III is proposed. It explains at a molecular level the reason for the ssb113 phenotype observed in Escherichia coli

Hypoxie-bedingte Hemmung der alveolären Flüssigkeitsresorption im Modell der isolierten, ventilierten und perfundierten Kaninchenlunge

Eine intakte alveolar-epitheliale Barriere ist für eine ungestörte Gasaustauschfunktion der Lunge von maßgeblicher Bedeutung. Beeinträchtigungen sowohl der passiven wie auch aktiven Barrierefunktion können hier zu einem folgenschweren Organversagen führen. Der Einfluss alveolärer Hypoxie auf aktive Resorptionsmechanismen des alveolären Epithels wurde bisher unzureichend unter physiologischen Bedingungen untersucht. Im vorliegenden ex-vivo Modell der isolierten, perfundierten und ventilierten Kaninchenlunge wurde der Einfluss von Hypoxie und/oder alveolärer Flüssigkeitsbeladung auf die Funktion des alveolären Epithels untersucht. Der das Epithel auskleidende Flüssigkeitsfilm (epithelial lining fluid (ELF)) wird über aktiven und passiven transmembranösen Flüssigkeitstransport (alveolar fluid clearence (AFC)) reguliert. In dem hier verwendeten Modell konnten wir zeigen, dass der alveoläre Natriumtransport die treibende Kraft des AFC darstellt. Der aktive, durch apikale Amilorid-sensitive Natriumkänale (ENaC) und basolateral lokalisierte Na,KATPase von alveolär nach interstitiell/intravasal gerichtete Natriumgradient führt zu einem konsekutiven Nachströmen von Wasser entlang des Ionengradienten. Die Deposition eines Flüssigkeitsbolus von 2,5 ml per Aerosolierung (engl. excess fluid load) führte im verwendeten Modell zu keiner relevanten Funktionsbeeinträchtigung des isolierten Organs. Es zeigte sich überraschenderweise sogar eine Stimulation des aktiven Natrium- und somit auch Flüssigkeitstransportes, im Sinne einer gesteigerten Ödemresorption. Demgegenüber führte eine alveoläre Hypoxie (zwei Stunden Ventilation mit 3,0 % Sauerstoff) zu einem signifikanten Abfall des AFC und konsekutiver Ödembildung. Ursache hierfür war eine um ca. 60 % reduzierte aktive Natriumresorption mit entsprechender Senkung des Flüssigkeitstransportes. Wir konnten somit erstmals in einem intakten isolierten Lungenmodell (unter Beibehaltung der Ventilation) zeigen, dass alveoläre Hypoxie, nicht jedoch eine iatrogene Flüssigkeitsbeladung des Alveolarraumes zu einer Störung der Ödemresorption der Lunge führt. Diese Beobachtung hat Implikationen für das Verständnis von Krankheitsbildern wie dem akuten Lungenversagen, dem Höhenlungenödem und dem Beinahe-Ertrinken.Alveolar-capillary barrier function is essential to maintain alveolar fluid balance and adequate gas exchange in the lung. Malfunction of either passive and/or active barrier could resolve in a detrimental organ failure So far the influence of alveolar hypoxia on active barrier function and its underlying machinery has been only inadequately described in a physiological environment. Using the ex-vivo model of the isolated, perfused and ventilated rabbit lung, this experimental study evaluated the influence of hypoxia and/or excess fluid load on alveolar epithelium. The epithelial lining fluid (ELF) is balanced via active and passive transmembrane alveolar fluid clearance (AFC). In the present study using the isolated, perfused and ventilated rabbit lung alveolar sodium transport (AST) was evidenced to be the driving force of the AFC. Sodium is actively pumped out of the alveolar epithelial cells into the interstitium by Na,K-ATPase, located on the basolateral membrane of the epithelium, which in turn drives the sodium uptake by amiloride-sensitive sodium channels (ENaCs), located on the apical membrane of the epithelium. This generates an osmotic gradient that drives water out of the alveolar space. The deposition of 2,5 ml excess fluid load resulted in no relevant barrier dysfunction in our isolated organ model. Surprisingly, we found the active sodium- and therefore fluid transport stimulated, ascribed by enhanced edema resorption. In contrast, alveolar hypoxia (2 hours of ventilation with 3,0 % Oxygen) led to a significant decrease of AFC and consecutive alveolar edema formation. Etiologic was the reduction of active AST by about 60 %, correspondingly resulting in a decreased AFC. Taken together, the deleterious effect of alveolar hypoxia, but not experimental alveolar deposition of excess fluid load, on the edema clearence in the distal lung was proofed for the first time in an intact isolated lung model under perpetuated ventilation. Our results establish ramifications for the disease pattern of acute lung injury (ALI), adult respiratory distress syndrome (ARDS), high altitude pulmonary edema (HAPE) and near-drowning syndrome

Voice Operated Information System in Slovak

Speech communication interfaces (SCI) are nowadays widely used in several domains. Automated spoken language human-computer interaction can replace human-human interaction if needed. Automatic speech recognition (ASR), a key technology of SCI, has been extensively studied during the past few decades. Most of present systems are based on statistical modeling, both at the acoustic and linguistic levels. Increased attention has been paid to speech recognition in adverse conditions recently, since noise-resistance has become one of the major bottlenecks for practical use of speech recognizers. Although many techniques have been developed, many challenges still have to be overcome before the ultimate goal -- creating machines capable of communicating with humans naturally -- can be achieved. In this paper we describe the research and development of the first Slovak spoken language dialogue system. The dialogue system is based on the DARPA Communicator architecture. The proposed system consists of the Galaxy hub and telephony, automatic speech recognition, text-to-speech, backend, transport and VoiceXML dialogue management modules. The SCI enables multi-user interaction in the Slovak language. Functionality of the SLDS is demonstrated and tested via two pilot applications, ``Weather forecast for Slovakia'' and ``Timetable of Slovak Railways''. The required information is retrieved from Internet resources in multi-user mode through PSTN, ISDN, GSM and/or VoIP network