一种简易的4.2K低温样品架及其应用

于2010-11-23批量导入

Consequências da análise inadequada de um experimento fatorial 2k am parcelas subdivididas e sem replicação

Em experimentos com vários fatores em que alguns são mais difíceis de mudar que outros, pode ser inconveniente executar as provas do experimento em uma forma completamente aleatória, levando o pesquisador a criar naturalmente uma restrição na ordem de execução para poupar tempo ou reduzir os custos. Este tipo de restrição pode resultar em uma generalização do planejamento fatorial, conhecida como experimentos em parcelas subdivididas. Na prática, é comum executar um experimento em parcelas subdivididas e analisá-lo como se fosse completamente aleatorizado. O objetivo principal do trabalho é avaliar o impacto de analisar um experimento com restrição na aleatorização como completamente aleatorizado

Doxycycline ameliorates 2K-1C hypertension-induced vascular dysfunction in rats by attenuating oxidative stress and improving nitric oxide bioavailability

Vascular dysfunction associated with two-kidney, one-clip (2K-1C) hypertension may result from both altered matrix metalloproteinase (MMP) activity and higher concentrations of reactive oxygen species (ROS). Doxycycline is considering the most potent MMP inhibitor of tetracyclines and attenuates 2K-1C hypertension-induced high blood pressure and chronic vascular remodeling. Doxycycline might also act as a ROS scavenger and this may contribute to the amelioration of some cardiovascular diseases associated with increased concentrations of ROS. We hypothesized that in addition to its MMP inhibitory effect, doxycycline attenuates oxidative stress and improves nitric oxide (NO) bioavailability in 2K-1C hypertension, thus improving hypertension-induced arterial endothelial dysfunction. Sham operated or 2K-1C hypertensive rats were treated with doxycycline 30 mg/kg/day (or vehicle). After 8 weeks of treatment, aortic rings were isolated to assess endothelium dependent vasorelaxation to A23187. Arterial and systemic levels of ROS were respectively measured using dihydroethidine (DHE) and thiobarbituric acid reactive substances (TBARS). Neutrophils-derived ROS were tested in vitro using the fluoroprobe Carboxy-H(2)DCFDA and human neutrophils stimulated with phorbol 12-myristate 13-acetate (PMA). NO levels were assessed in rat aortic endothelial cells by confocal microscopy. Aortic MMP activity was determined by in situ zymography. Doxycycline attenuated 2K-1C hypertension (169 +/- 17.3 versus 209 +/- 10.9 mm Hg in hypertensive controls, p < 0.05) and protected against hypertension-induced reduction in endothelium-dependent vasorelaxation to A23187 (p < 0.05). Doxycycline also decreased hypertension-induced oxidative stress (p <= 0.05), higher MMP activity (p < 0.01) and improved NO levels in aortic endothelial cells (p < 0.01). Therefore, doxycycline ameliorates 2K-1C hypertension-induced endothelial dysfunction in aortas by inhibiting oxidative stress generation and improving NO bioavailability, in addition to its inhibitory effects on MMP activity. (C) 2012 Elsevier Inc. All rights reserved.

Prevention, diagnosis, therapy and follow-up care of sepsis: 1st revision of S-2k guidelines of the German Sepsis Society (Deutsche Sepsis-Gesellschaft e.V. (DSG)) and the German Interdisciplinary Association of Intensive Care and Emergency Medicine (Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin (DIVI))

Practice guidelines are systematically developed statements and recommendations that assist the physicians and patients in making decisions about appropriate health care measures for specific clinical circumstances taking into account specific national health care structures. The 1(st) revision of the S-2k guideline of the German Sepsis Society in collaboration with 17 German medical scientific societies and one self-help group provides state-of-the-art information (results of controlled clinical trials and expert knowledge) on the effective and appropriate medical care (prevention, diagnosis, therapy and follow-up care) of critically ill patients with severe sepsis or septic shock. The guideline had been developed according to the "German Instrument for Methodological Guideline Appraisal" of the Association of the Scientific Medical Societies (AWMF). In view of the inevitable advancements in scientific knowledge and technical expertise, revisions, updates and amendments must be periodically initiated. The guideline recommendations may not be applied under all circumstances. It rests with the clinician to decide whether a certain recommendation should be adopted or not, taking into consideration the unique set of clinical facts presented in connection with each individual patient as well as the available resources.

Pipelined Radix- 2k Feedforward FFT Architectures

The appearance of radix-$2^{2}$ was a milestone in the design of pipelined FFT hardware architectures. Later, radix-$2^{2}$ was extended to radix-$2^{k}$ . However, radix-$2^{k}$ was only proposed for single-path delay feedback (SDF) architectures, but not for feedforward ones, also called multi-path delay commutator (MDC). This paper presents the radix-$2^{k}$ feedforward (MDC) FFT architectures. In feedforward architectures radix-$2^{k}$ can be used for any number of parallel samples which is a power of two. Furthermore, both decimation in frequency (DIF) and decimation in time (DIT) decompositions can be used. In addition to this, the designs can achieve very high throughputs, which makes them suitable for the most demanding applications. Indeed, the proposed radix-$2^{k}$ feedforward architectures require fewer hardware resources than parallel feedback ones, also called multi-path delay feedback (MDF), when several samples in parallel must be processed. As a result, the proposed radix-$2^{k}$ feedforward architectures not only offer an attractive solution for current applications, but also open up a new research line on feedforward structures.

Regulated Cleavages at the West Nile Virus NS4A-2K-NS4B Junctions Play a Major Role in Rearranging Cytoplasmic Membranes and Golgi Trafficking of the NS4A Protein

A common feature associated with the replication of most RNA viruses is the formation of a unique membrane environment encapsulating the viral replication complex. For their part, flaviviruses are no exception, whereupon infection causes a dramatic rearrangement and induction of unique membrane structures within the cytoplasm of infected cells. These virus-induced membranes, termed paracrystalline arrays, convoluted membranes, and vesicle packets, all appear to have specific functions during replication and are derived from different organelles within the host cell. The aim of this study was to identify which protein(s) specified by the Australian strain of West Nile virus, Kunjin virus (KUNV), are responsible for the dramatic membrane alterations observed during infection. Thus, we have shown using immunolabeling of ultrathin cryosections of transfected cells that expression of the KUNV polyprotein intermediates NS4A-4B and NS213-34A, as well as that of individual NS4A proteins with and without the C-terminal transmembrane domain 2K, resulted in different degrees of rearrangement of cytoplasmic membranes. The formation of the membrane structures characteristic for virus infection required coexpression of an NS4A-NS4B cassette with the viral protease NS2B-3pro which was shown to be essential for the release of the individual NS4A and NS4B proteins. Individual expression of NS4A protein retaining the C-terminal transmembrane domain 2K resulted in the induction of membrane rearrangements most resembling virus-induced structures, while removal of the 2K domain led to a less profound membrane rearrangement but resulted in the redistribution of the NS4A protein to the Golgi apparatus. The results show that cleavage of the KUNV polyprotein NS4A-4B by the viral protease is the key initiation event in the induction of membrane rearrangement and that the NS4A protein intermediate containing the uncleaved C-terminal transmembrane domain plays an essential role in these membrane rearrangements.

Efficient modular exponentiation-based puzzles for denial-of-service protection

Client puzzles are moderately-hard cryptographic problems neither easy nor impossible to solve that can be used as a counter-measure against denial of service attacks on network protocols. Puzzles based on modular exponentiation are attractive as they provide important properties such as non-parallelisability, deterministic solving time, and linear granularity. We propose an efficient client puzzle based on modular exponentiation. Our puzzle requires only a few modular multiplications for puzzle generation and verification. For a server under denial of service attack, this is a significant improvement as the best known non-parallelisable puzzle proposed by Karame and Capkun (ESORICS 2010) requires at least 2k-bit modular exponentiation, where k is a security parameter. We show that our puzzle satisfies the unforgeability and difficulty properties defined by Chen et al. (Asiacrypt 2009). We present experimental results which show that, for 1024-bit moduli, our proposed puzzle can be up to 30 times faster to verify than the Karame-Capkun puzzle and 99 times faster than the Rivest et al.'s time-lock puzzle.

Melt-textured YBa2Cu3O7-x wires having plate-like grains

YBCO wires which consist of well oriented plate-like fine grains are fabricated using a moving furnace to achieve higher mechanical strength. Melt-texturing experiments have been undertaken on YBCO wires with two different compositions: YBa1.5Cu2.9O7-x, and YBa1.8Cu3.0O7-x. Wires are extruded from a mixture of precursor powders (formed by a coprecipitation process) then textured by firing in a moving furnace. Size of secondary phases such as barium cuprate and copper oxide, and overall composition of the sample affect the orientation of the fine grains. At zero magnetic field, the YBa1.5Cu2.9O7-x wire shows the highest critical current density of 1,450 Acm-2 and 8,770 Acm-2 at 77K and 4.2K, respectively. At 1 T, critical current densities of 30 Acm-2 and 200 Acm-2, respectively, are obtained at 77K and 4.2K. Magnetisation curves are also obtained for one sample to evaluate critical current density using the Bean model. Analysis of the microstructure indicates that the starting composition of the green body significantly affects the achievement of grain alignment via melt-texturing processes.

A non-malleable group key exchange protocol robust against active insiders

In this paper we make progress towards solving an open problem posed by Katz and Yung at CRYPTO 2003. We propose the first protocol for key exchange among n ≥2k+1 parties which simultaneously achieves all of the following properties: 1. Key Privacy (including forward security) against active attacks by group outsiders, 2. Non-malleability — meaning in particular that no subset of up to k corrupted group insiders can ‘fix’ the agreed key to a desired value, and 3. Robustness against denial of service attacks by up to k corrupted group insiders. Our insider security properties above are achieved assuming the availability of a reliable broadcast channel.