1,347 research outputs found

    Functional Bosonization of Non-Relativistic Fermions in (2+1)(2+1) Dimensions

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    We analyze the universality of the bosonization rules in non-relativistic fermionic systems in (2+1)d(2+1)d. We show that, in the case of linear fermionic dispersion relations, a general fermionic theory can be mapped into a gauge theory in such a way that the fermionic density maps into a magnetic flux and the fermionic current maps into a transverse electric field. These are universal rules in the sense that they remain valid whatever the interaction considered. We also show that these rules are universal in the case of non-linear dispersion relations provided we consider only density-density interactions. We apply the functional bosonization formalism to a non-relativistic and non-local massive Thirring-like model and evaluate the spectrum of collective excitations in several limits. In the large mass limit, we are able to exactly calculate this spectrum for arbitrary density-density and current-current interactions. We also analyze the massless case and show that it has no collective excitations for any density-density potential in the Gaussian approximation. Moreover, the presence of current interactions may induce a gapless mode with a linear dispersion relation.Comment: 26 Pages, LaTeX, Final version to appear in International Journal of Modern Physics

    Loss of Arabidopsis matrix metalloproteinase-5 affects root development and root bacterial communities during drought stress

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    Matrix metalloproteinases (MMPs) are zinc-dependent endo-peptidases that in mammals are known to be involved in remodeling the extracellular matrix (ECM) in developmental and pathological processes. In this study, we report At5-MMP of Arabidopsis thaliana to be important for root development and root bacterial communities. At5-MMP is mainly localized in the root vasculature and lateral root, an At5-MMP T-DNA insertion mutant (mmp5 KO) showed reduced root growth and a lower number of root apexes, causing reduced water uptake from the soil. Subsequently, mmp5 KO is sensitive to drought stress. Inhibited auxin transport was accompanied with resistance to indole-3-acetic acid (IAA), 2, 4-dichlorophenoxyacetic acid (2, 4-D), and 1-naphthaleneacetic acid (NAA). The content of endogenous abscisic acid (ABA) was lower in roots of mmp5 KO than in wild type. Genes responsive to ABA as well as genes encoding enzymes of the proline biosynthesis were expressed to a lower extent in mmp5 KO than in wild type. Moreover, drought stress modulated root-associated bacterial communities of mmp5 KO: the number of Actinobacteria increased. Therefore, At5-MMP modulates auxin/ABA signaling rendering the plant sensitive to drought stress and recruiting differential root bacterial communities

    Case study: house rules

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    Abstract only.This is a case about rules, what they mean, and when to follow them. The case consists of two stories, one set in the halls of a major university and the other, a considerable time ago, in a Midwestern barber shop. In the first instance the Dean of a major Business Administration faculty must choose between following the rules concerning paying a faculty member for additional work, therefore forgoing an opportunity to secure a great deal of money for the faculty, or pay the faculty member therefore possibly violating the faculty's Collective Agreement but, in so doing, securing the large financial contribution. The Dean asks one of his advisors to recommend a course of action. The advisor recounts a story where a barber faced a similar situation, having to choose between breaking a law prohibiting gambling in the back room of his barbershop, or forgo the additional business the recreational, but illegal, poker game generated. The similarities between the stories are used to discuss issues of ethics, the meaning of rules, and "Pro-Social Rule Breaking"

    Actin-myosin–based contraction is responsible for apoptotic nuclear disintegration

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    Membrane blebbing during the apoptotic execution phase results from caspase-mediated cleavage and activation of ROCK I. Here, we show that ROCK activity, myosin light chain (MLC) phosphorylation, MLC ATPase activity, and an intact actin cytoskeleton, but not microtubular cytoskeleton, are required for disruption of nuclear integrity during apoptosis. Inhibition of ROCK or MLC ATPase activity, which protect apoptotic nuclear integrity, does not affect caspase-mediated degradation of nuclear proteins such as lamins A, B1, or C. The conditional activation of ROCK I was sufficient to tear apart nuclei in lamin A/C null fibroblasts, but not in wild-type fibroblasts. Thus, apoptotic nuclear disintegration requires actin-myosin contractile force and lamin proteolysis, making apoptosis analogous to, but distinct from, mitosis where nuclear disintegration results from microtubule-based forces and from lamin phosphorylation and depolymerization

    Scheme Independence at First Order Phase Transitions and the Renormalisation Group

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    We analyse approximate solutions to an exact renormalisation group equation with particular emphasis on their dependence on the regularisation scheme, which is kept arbitrary. Physical quantities related to the coarse-grained potential of scalar QED display universal behaviour for strongly first-order phase transitions. Only subleading corrections depend on the regularisation scheme and are suppressed by a sufficiently large UV scale. We calculate the relevant coarse-graining scale and give a condition for the applicability of Langer's theory of bubble nucleation.Comment: 12 pages, LaTeX, 4 figures included (needs epsfig.sty), two equations added, typo correcte

    Brain fatty acid synthase activates PPARa to maintain energy homeostasis

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    Central nervous system control of energy balance affects susceptibility to obesity and diabetes, but how fatty acids, malonyl-CoA, and other metabolites act at this site to alter metabolism is poorly understood. Pharmacological inhibition of fatty acid synthase (FAS), rate limiting for de novo lipogenesis, decreases appetite independently of leptin but also promotes weight loss through activities unrelated to FAS inhibition. Here we report that the conditional genetic inactivation of FAS in pancreatic β cells and hypothalamus produced lean, hypophagic mice with increased physical activity and impaired hypothalamic PPARα signaling. Administration of a PPARα agonist into the hypothalamus increased PPARα target genes and normalized food intake. Inactivation of β cell FAS enzyme activity had no effect on islet function in culture or in vivo. These results suggest a critical role for brain FAS in the regulation of not only feeding, but also physical activity, effects that appear to be mediated through the provision of ligands generated by FAS to PPARα. Thus, 2 diametrically opposed proteins, FAS (induced by feeding) and PPARα (induced by starvation), unexpectedly form an integrative sensory module in the central nervous system to orchestrate energy balance

    Anidulafungin compared with fluconazole for treatment of candidemia and other forms of invasive candidiasis caused by Candida albicans: a multivariate analysis of factors associated with improved outcome

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    <p>Abstract</p> <p>Background</p> <p><it>Candida albicans </it>is the most common cause of candidemia and other forms of invasive candidiasis. Systemic infections due to <it>C. albicans </it>exhibit good susceptibility to fluconazole and echinocandins. However, the echinocandin anidulafungin was recently demonstrated to be more effective than fluconazole for systemic <it>Candida </it>infections in a randomized, double-blind trial among 245 patients. In that trial, most infections were caused by <it>C. albicans</it>, and all respective isolates were susceptible to randomized study drug. We sought to better understand the factors associated with the enhanced efficacy of anidulafungin and hypothesized that intrinsic properties of the antifungal agents contributed to the treatment differences.</p> <p>Methods</p> <p>Global responses at end of intravenous study treatment in patients with <it>C. albicans </it>infection were compared post-hoc. Multivariate logistic regression analyses were performed to predict response and to adjust for differences in independent baseline characteristics. Analyses focused on time to negative blood cultures, persistent infection at end of intravenous study treatment, and 6-week survival.</p> <p>Results</p> <p>In total, 135 patients with <it>C. albicans </it>infections were identified. Among these, baseline APACHE II scores were similar between treatment arms. In these patients, global response was significantly better for anidulafungin than fluconazole (81.1% vs 62.3%; 95% confidence interval [CI] for difference, 3.7-33.9). After adjusting for baseline characteristics, the odds ratio for global response was 2.36 (95% CI, 1.06-5.25). Study treatment and APACHE II score were significant predictors of outcome. The most predictive logistic regression model found that the odds ratio for study treatment was 2.60 (95% CI, 1.14-5.91) in favor of anidulafungin, and the odds ratio for APACHE II score was 0.935 (95% CI, 0.885-0.987), with poorer responses associated with higher baseline APACHE II scores. Anidulafungin was associated with significantly faster clearance of blood cultures (log-rank <it>p </it>< 0.05) and significantly fewer persistent infections (2.7% vs 13.1%; <it>p </it>< 0.05). Survival through 6 weeks did not differ between treatment groups.</p> <p>Conclusions</p> <p>In patients with <it>C. albicans </it>infection, anidulafungin was more effective than fluconazole, with more rapid clearance of positive blood cultures. This suggests that the fungicidal activity of echinocandins may have important clinical implications.</p> <p>Trial registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00058682">NCT00058682</a></p
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