Extremely anisotropic suppression of huge enhancement of electrical resistivity by magnetic field in α-R2S3 (R = Sm, Dy).

The electrical resistivity ρ and magnetization M of α-R 2S3 (R = Sm, Dy) single crystals have been measured in various magnetic fields lying in the ac-plane of an orthorhombic crystal structure. The measurements have been carried out by rotating the single crystals around the b-axis (being set parallel to a horizontal direction), corresponding to the longitudinal direction of needle-shaped single crystals, in vertical magnetic fields. The electrical resistivity under no magnetic field shows huge enhancement in a narrow temperature range around the successive magnetic transition temperatures, as reported previously. Such enhancement is suppressed rapidly by applying a magnetic field, which has been clearly seen as diminishing of the ρ(T) peak. The magnetic field along the easy magnetization axis; H easy, moves the ρ(T) peak toward higher temperature with diminishing it, while the magnetic field along the hard magnetization axis; H hard, moves it to lower temperature. The suppression effect is extremely anisotropic for the orientation of the magnetic field lying in the ac-plane. It has been concluded that H easy suppresses the ρ enhancement most strongly. The suppression effect under H easy is more than 200 times larger at least in some cases than that under H hard

Localized indirect excitons in a short-period GaAs/AlAs superlattice

We have studied the optical properties of a short-period superlattice composed of 20.4-Å GaAs and 14.7-Å AlAs layers. The superlattice behaves as an indirect-gap material. A slow and nonexponential decay of the luminescence can be interpreted as the emission from the Λ indirect excitons localized at the GaAs/AlAs interfaces. The temperature dependence of the exciton decay time can be explained in terms of a transition by phonon-assisted tunneling, followed by a nonradiative transition

Ectopic cardiovascular fat in middle-aged men: effects of race/ethnicity, overall and central adiposity. The ERA JUMP study.

Background/objectivesHigher volumes of ectopic cardiovascular fat (ECF) are associated with greater risk of coronary heart disease (CHD). Identifying factors that are associated with ECF volumes may lead to new preventive efforts to reduce risk of CHD. Significant racial/ethnic differences exist for overall and central adiposity measures, which are known to be associated with ECF volumes. Whether racial/ethnic differences also exist for ECF volumes and their associations with these adiposity measures remain unclear.Subjects/methodsBody mass index (BMI), computerized tomography-measured ECF volumes (epicardial, pericardial and their summation) and visceral adipose tissue (VAT) were examined in a community-based sample of 1199 middle-aged men (24.2% Caucasians, 7.0% African-Americans, 23.6% Japanese-Americans, 22.0% Japanese, 23.2% Koreans).ResultsSignificant racial/ethnic differences existed in ECF volumes and their relationships with BMI and VAT. ECF volumes were the highest among Japanese-Americans and the lowest among African-Americans. The associations of BMI and VAT with ECF differed by racial/ethnic groups. Compared with Caucasians, for each 1-unit increase in BMI, African-Americans had lower, whereas Koreans had higher increases in ECF volumes (P-values<0.05 for both). Meanwhile, compared with Caucasians, for each 1-unit increase in log-transformed VAT, African-Americans, Japanese-Americans and Japanese had similar increases, whereas Koreans had a lower increase in ECF volumes (P-value<0.05).ConclusionsRacial/ethnic groups differed in their propensity to accumulate ECF at increasing level of overall and central adiposity. Future studies should evaluate whether reducing central adiposity or overall weight will decrease ECF volumes more in certain racial/ethnic groups. Evaluating these questions might help in designing race-specific prevention strategy of CHD risk associated with higher ECF

Development of a stochastic computational fluid dynamics approach for offshore wind farms

In this paper, a method for stochastic analysis of an offshore wind farm using computational fluid dynamics (CFD) is proposed. An existing offshore wind farm is modelled using a steady-state CFD solver at several deterministic input ranges and an approximation model is trained on the CFD results. The approximation model is then used in a Monte-Carlo analysis to build joint probability distributions for values of interest within the wind farm. The results are compared with real measurements obtained from the existing wind farm to quantify the accuracy of the predictions. It is shown that this method works well for the relatively simple problem considered in this study and has potential to be used in more complex situations where an existing analytical method is either insufficient or unable to make a good prediction

Washingtonia filifera seed extracts inhibit the islet amyloid polypeptide fibrils formations and α-amylase and α-glucosidase activity

Washingtonia filifera seeds have revealed to possess antioxidant properties, butyrylcholinesterase and xanthine oxidase inhibition activities. The literature has indicated a relationship between Alzheimer’s disease (AD) and type-2 diabetes (T2D). Keeping this in mind, we have now evaluated the inhibitory properties of W. filifera seed extracts on α-amylase, α-glucosidase enzyme activity and the Islet Amyloid Polypeptide (IAPP) fibrils formation. Three extracts from seeds of W. filifera were evaluated for their enzyme inhibitory effect and IC50 values were calculated for all the extracts. The inhibition mode was investigated by Lineweaver-Burk plot analysis and the inhibition of IAPP aggregate formation was monitored. W. filifera methanol seed extract appears as the most potent inhibitor of α-amylase, α-glucosidase, and for the IAPP fibril formation. Current findings indicate new potential of this extract that could be used for the identification or development of novel potential agents for T2D and AD

STUDIE ON METALLÜBERGANG BEI DER SYNCHRONISIERTEN KONTROLLE DER DRAHTZUFÜHRUNG UND BEI STROM WELLENFORM

Za zavarivanje tankih limova s vrlo niskim unosom topline i minimalnim štrcanjem koristi se inačica MAG zavarivanje kratkim spojevima pri kojem se mijenja smjer gibanja elektrodne žice. Ako se takav stabilan prijenos može ostvariti u području globularnoga, tj. prijelaznog luka u zaštiti plina CO2, postiže se dodatna produktivnost. Za dane uvjete u ovom radu je opisan razvoj međuspremnika žice tzv. Buffer Position Control uređaja koji upravlja dodavanjem žice između motora koji gura i drugoga koji vuče žicu te može kompenzirati konstantnu brzinu dodavanja, uz primjenu tzv. Pulsed Dip Transfer Process, tj. kombinacije prijenosa metala impulsima i kratkim spojevima, čime se tijekom trajanja električnog luka stabilizira prijenos metalnih kapi za ravnu statičku značajku (CV-constant voltage). Primjenom takvoga valnog oblika struje poboljšava se prijenos topline u osnovni materijal. Dodatno su analizirana načela upravljanja procesom i utjecaj zavarivanja velikim brzinama na vrlo tankim limovima uz pojavu minimalnog štrcanja.A gas metal arc welding process that changes the wire feed direction according to the arc phenomena has been proposed and applied to a fi eld of the ultra-sheet plate joining on MAG welding process, due to the ultra-low spatter generation and the low heat input into the base metal in a current range of the short-circuit transfer mode. When such the welding process can realize the stable metal transfer in a current range of the globular transfer mode under the carbon dioxide shielding gas supplying, it can contribute the improvement of the further productivity. Under the circumstances, the authors have developed the Buffer Position Control which controls the interference reduction of the wire feed direction between the push feeder and the pull feeder and can compensate the constant mean wire feed rate, and the Pulsed Dip Transfer Process which forms the pulsatile output of the welding current during arc duration to stabilize the metal transfer by the constant voltage characteristic and improve the heat input to the base metal. In this paper, the principle of these controls and the effect of high speed welding with ultra-low spatter generation of the sheet metal joining will be presented.Beim Schweißen von dünnen Blechen mit einem sehr niedrigen Wärmeeintrag und mit minimalen Spritzen wird MAG Schweißen benutzt bei dem sich die Richtung der Drahtelektrode ändert. Falls sich so ein stabiler Metallübergang erreicht, im Bereich der globularen bzw. Übergehenden Lichtbogen beim CO2 Gas, kann man eine erweiterte Produktivität haben. Für die Konditionen in dieser Arbeit wurde die Entwicklung von dem Zwischendrahtbuffer beschrieben, der so genannter Buffer Position Control die die Drahtzufuhr reguliert zwischen dem Motor der den Draht schiebt und einen anderen Motor der den Draht zieht, und diese Bufferposition kann die konstante Drahtzufuhrgeschwindigkeit kompensieren und einen Pulsed Dip Transfer Process erreichen, bzw. eine Kombination des Metallübergangs mit Impulsen und Kurzlichtbogen wobei die statische Charakteristik des Lichtbogen gerade ist (CV-constant voltage). Mit der Anwendung so einer Strom Wellenform verbessert sich der Wärmeübergang in das Grundmaterial. Zusätzlich wurden die Prinzipen der Prozesskontrolle und der Einfl uss beim Schweißen mit hoher Geschwindigkeit an sehr dünnen Blechen mit minimalen Spritzen gezeigt

Vitamin D deficiency is associated with IL-6 levels and monocyte activation in HIV-infected persons

Immune activation plays a key role in HIV pathogenesis. Markers of inflammation have been associated with vitamin D deficiency in the general population. Studies have also demonstrated associations of vitamin D deficiency with increased risk of HIV progression and death. The relationship between persistent inflammation and immune activation during chronic HIV infection and vitamin D deficiency remains unclear.Cryopreserved specimens were analyzed from 663 participants at the time of enrollment from the Study to Understand the Natural History of HIV/AIDS in the Era of Effective Therapy (SUN Study) from 2004 to 2006. Biomarkers of inflammation, atherosclerosis, and coagulation were measured using enzyme-linked immunosorbent assays (ELISAs) and electrochemiluminescence. 25(OH)D, the stable precursor form of vitamin D, was measured using a radioimmunoassay with levels defined as: normal (≥30ng/mL), insufficient (20-29 ng/mL) and deficient (<20 ng/mL). Monocyte phenotypes were assessed by flow cytometry. Linear and logistic regression models were used to determine statistical associations between biomarkers and vitamin D deficiency.25(OH)D levels were deficient in 251 (38%) participants, insufficient in 222 (34%), and normal in 190 (29%). Patients with vitamin D deficiency, when compared to those with insufficient or normal vitamin D levels, had increased levels of IL-6 (23%; p<0.01), TNF-α (21%, p = 0.03), D-dimer (24%, p = 0.01), higher proportions of CD14dimCD16+ (22%, p<0.01) and CX3CR1+ monocytes (48%; p<0.001) and decreased frequency of CCR2+ monocytes (-3.4%, p<0.001). In fully adjusted models, vitamin D associations with abnormal biomarker levels persisted for IL-6 levels and CX3CR1+ and CCR2+ phenotypes.Vitamin D deficiency is associated with greater inflammation and activated monocyte phenotypes. The role of vitamin D deficiency in persistent immune activation and associated complications during chronic HIV disease should be further evaluated as a possible target for intervention

Low levels of β-lactam antibiotics induce extracellular DNA release and biofilm formation in Staphylococcus aureus.

UNLABELLED: Subminimal inhibitory concentrations of antibiotics have been shown to induce bacterial biofilm formation. Few studies have investigated antibiotic-induced biofilm formation in Staphylococcus aureus, an important human pathogen. Our goal was to measure S. aureus biofilm formation in the presence of low levels of β-lactam antibiotics. Fifteen phylogenetically diverse methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains were employed. Methicillin, ampicillin, amoxicillin, and cloxacillin were added to cultures at concentrations ranging from 0× to 1× MIC. Biofilm formation was measured in 96-well microtiter plates using a crystal violet binding assay. Autoaggregation was measured using a visual test tube settling assay. Extracellular DNA was quantitated using agarose gel electrophoresis. All four antibiotics induced biofilm formation in some strains. The amount of biofilm induction was as high as 10-fold and was inversely proportional to the amount of biofilm produced by the strain in the absence of antibiotics. MRSA strains of lineages USA300, USA400, and USA500 exhibited the highest levels of methicillin-induced biofilm induction. Biofilm formation induced by low-level methicillin was inhibited by DNase. Low-level methicillin also induced DNase-sensitive autoaggregation and extracellular DNA release. The biofilm induction phenotype was absent in a strain deficient in autolysin (atl). Our findings demonstrate that subminimal inhibitory concentrations of β-lactam antibiotics significantly induce autolysin-dependent extracellular DNA release and biofilm formation in some strains of S. aureus. IMPORTANCE: The widespread use of antibiotics as growth promoters in agriculture may expose bacteria to low levels of the drugs. The aim of this study was to investigate the effects of low levels of antibiotics on bacterial autoaggregation and biofilm formation, two processes that have been shown to foster genetic exchange and antibiotic resistance. We found that low levels of β-lactam antibiotics, a class commonly used in both clinical and agricultural settings, caused significant autoaggregation and biofilm formation by the important human pathogen Staphylococcus aureus. Both processes were dependent on cell lysis and release of DNA into the environment. The effect was most pronounced among multidrug-resistant strains known as methicillin-resistant S. aureus (MRSA). These results may shed light on the recalcitrance of some bacterial infections to antibiotic treatment in clinical settings and the evolution of antibiotic-resistant bacteria in agricultural settings