621 research outputs found

    Half-metallicity and Slater-Pauling behavior in the ferromagnetic Heusler alloys

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    Introductory chapter for the book "Halfmetallic Alloys - Fundamentals and Applications" to be published in the series Springer Lecture Notes on Physics, P. H. Dederichs and I. Galanakis (eds). It contains a review of the theoretical work on the half-metallic Heusler alloys.Comment: Introductory chapter for the book "Halfmetallic Alloys - Fundamentals and Applications" to be published in the series Springer Lecture Notes on Physics, P. H. Dederichs and I. Galanakis (eds

    Structure and Kinetic Investigation of Streptococcus pyogenes Family GH38 α-Mannosidase

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    BACKGROUND: The enzymatic hydrolysis of alpha-mannosides is catalyzed by glycoside hydrolases (GH), termed alpha-mannosidases. These enzymes are found in different GH sequence-based families. Considerable research has probed the role of higher eukaryotic "GH38" alpha-mannosides that play a key role in the modification and diversification of hybrid N-glycans; processes with strong cellular links to cancer and autoimmune disease. The most extensively studied of these enzymes is the Drosophila GH38 alpha-mannosidase II, which has been shown to be a retaining alpha-mannosidase that targets both alpha-1,3 and alpha-1,6 mannosyl linkages, an activity that enables the enzyme to process GlcNAc(Man)(5)(GlcNAc)(2) hybrid N-glycans to GlcNAc(Man)(3)(GlcNAc)(2). Far less well understood is the observation that many bacterial species, predominantly but not exclusively pathogens and symbionts, also possess putative GH38 alpha-mannosidases whose activity and specificity is unknown. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that the Streptococcus pyogenes (M1 GAS SF370) GH38 enzyme (Spy1604; hereafter SpGH38) is an alpha-mannosidase with specificity for alpha-1,3 mannosidic linkages. The 3D X-ray structure of SpGH38, obtained in native form at 1.9 A resolution and in complex with the inhibitor swainsonine (K(i) 18 microM) at 2.6 A, reveals a canonical GH38 five-domain structure in which the catalytic "-1" subsite shows high similarity with the Drosophila enzyme, including the catalytic Zn(2+) ion. In contrast, the "leaving group" subsites of SpGH38 display considerable differences to the higher eukaryotic GH38s; features that contribute to their apparent specificity. CONCLUSIONS/SIGNIFICANCE: Although the in vivo function of this streptococcal GH38 alpha-mannosidase remains unknown, it is shown to be an alpha-mannosidase active on N-glycans. SpGH38 lies on an operon that also contains the GH84 hexosaminidase (Spy1600) and an additional putative glycosidase. The activity of SpGH38, together with its genomic context, strongly hints at a function in the degradation of host N- or possibly O-glycans. The absence of any classical signal peptide further suggests that SpGH38 may be intracellular, perhaps functioning in the subsequent degradation of extracellular host glycans following their initial digestion by secreted glycosidases

    A new isotropic cell for studying the thermo-mechanical behavior of unsaturated expansive clays

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    This paper presents a new suction-temperature controlled isotropic cell that can be used to study the thermo-mechanical behavior of unsaturated expansive clays. The vapor equilibrium technique is used to control the soil suction; the temperature of the cell is controlled using a thermostat bath. The isotropic pressure is applied using a volume/pressure controller that is also used to monitor the volume change of soil specimen. Preliminary experimental results showed good performance of the cell

    Action theory and the value of sport

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    I present a corrective to the formalist and conventionalist down-playing of physical actions in the understanding of the value of sport. I give a necessarily brief account of the Causal Theory of Action (CTA) and its implications for the normativity of actions. I show that the CTA has limitations, particularly in the case of failed or incomplete actions, and I show that failed or incomplete actions are constitutive of sport. This allows me to open up the space for another model, drawn from Aristotle, for failed or incomplete actions, conceived of as ‘doables’. This avoids some of the problems of the CTA. I explain the importance of difficult but doable actions, at which athletes often fail, and suggest that this establishes pro tanto value. Finally, I claim that this account of the actions that are constitutive of sport deepens our understanding of the value of sport as a whole

    Play and games:An opinionated introduction

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    Philosophy has a schizophrenic relationship with games. On the one hand, philosophers love using games as model, arguing that phenomena as diverse as linguistic meaning, meta‐ethics, normative ethics, applied ethics, law, and aesthetics can be illuminated via an analogy with games. On the other hand, there is scant focused discussion of the concept of a game as such. This is problematic; the appeal to games as a model to clarify philosophically puzzling questions has limited utility if games themselves (and the concept of a game) are poorly understood. Moreover, playing games plausibly is an important element in a good life; anyone interested in the theory of welfare, a traditional philosophical topic, should be interested in games. We play games, but if anything, play itself has been more neglected by philosophers than games. This neglect is unwarranted. Historically, philosophy has investigated foundational questions about human nature, and a disposition to play plausibly is a deep part of human nature. Moreover, play is an important concept in evolutionary biology and psychology, yet those working in those fields struggle to define the concept to their own satisfaction. E.O. Wilson went so far as to remark that “no behavioural concept has proved more ill‐defined, elusive, controversial, and even unfashionable than play.” One might have hoped philosophers could help here. In this paper, I provide an opinionated introduction to the philosophy of play and games.Some time ago, an innocent bystander, after glancing through a copy of Mind, asked me, ‘Why do philosophers talk so much about games? Do they play them a lot or something?’ (Midgley, 1974: 321

    Use of a differential pressure transducer for the monitoring of soil volume change in cyclic triaxial test on unsaturated soils

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    A new experimental set-up using a differential pressure transducer was developed, that enables the monitoring of volume changes in cyclic triaxial tests on unsaturated soils. Calibration tests were performed in order to analyze the performance of the set-up, especially in terms of loading frequencies. Based on calibration results, a low frequency of 0.05 Hz was adopted for the tests carried out on the unsaturated loess from northern France. Five water contents were considered in the tests. The obtained results have confirmed the efficiency of the new system for volume change monitoring under cyclic loading. The effect of water content on the cyclic behavior of loess was clearly evidenced. Finally, some suggestions were made to improve the accuracy of the system

    A Rapid Host-protein Test for Differentiating Bacterial From Viral Infection: Apollo Diagnostic Accuracy Study

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    OBJECTIVES: To determine the diagnostic accuracy of a rapid host-protein test for differentiating bacterial from viral infections in patients who presented to the emergency department (ED) or urgent care center (UCC). METHODS: This was a prospective multicenter, blinded study. MeMed BV (MMBV), a test based on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), interferon gamma-inducible protein-10 (IP-10), and C-reactive protein (CRP), was measured using a rapid measurement platform. Patients were enrolled from 9 EDs and 3 UCCs in the United States and Israel. Patients \u3e3 months of age presenting with fever and clinical suspicion of acute infection were considered eligible. MMBV results were not provided to the treating clinician. MMBV results (bacterial/viral/equivocal) were compared against a reference standard method for classification of infection etiology determined by expert panel adjudication. Experts were blinded to MMBV results. They were provided with comprehensive patient data, including laboratory, microbiological, radiological and follow-up. RESULTS: Of 563 adults and children enrolled, 476 comprised the study population (314 adults, 162 children). The predominant clinical syndrome was respiratory tract infection (60.5% upper, 11.3% lower). MMBV demonstrated sensitivity of 90.0% (95% confidence interval [CI]: 80.3-99.7), specificity of 92.8% (90.0%-95.5%), and negative predictive value of 98.8% (96.8%-99.6%) for bacterial infections. Only 7.2% of cases yielded equivocal MMBV scores. Area under the curve for MMBV was 0.95 (0.90-0.99). CONCLUSIONS: MMBV had a high sensitivity and specificity relative to reference standard for differentiating bacterial from viral infections. Future implementation of MMBV for patients with suspected acute infections could potentially aid with appropriate antibiotic decision-making
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