1,347 research outputs found
Functional Bosonization of Non-Relativistic Fermions in Dimensions
We analyze the universality of the bosonization rules in non-relativistic
fermionic systems in . 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
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
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
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
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
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Cost analysis of noninvasive blood-based microRNA testing versus CT scans for follow-up in patients with testicular germ-cell tumors
BACKGROUND: Our group has developed a noninvasive blood-based microRNA (miRNA) test for improving diagnosis, disease monitoring, and relapse detection in malignant testicular germ-cell tumors (TGCTs). Performance analysis suggests the test is likely to have comparable sensitivity and specificity in detecting TGCT as computed tomography (CT), thus reducing the need for serial CT scans for follow-up monitoring, with associated reductions in cumulative radiation burden and second cancer risk. To facilitate clinical adoption, we undertook a cost analysis to identify the budget impact of replacing CT scans with miRNA testing within health care systems. METHODS: The TGCT aftercare pathway was mapped out using National Comprehensive Cancer Network guidelines. A Markov model was built to simulate the impact of the miRNA test on TGCT aftercare costs. Incidence, treatment probabilities, relapse rate, and death rate data were collected from published studies to populate the model. RESULTS: Applying our model to the US health care system, the miRNA test has the potential to save up to $69 million per year in aftercare expenses related to TGCT treatment, with exact savings depending on the adoption rate and test price. CONCLUSION: This analysis demonstrates the potential positive budget impact of adopting miRNA testing in place of CT scans in the clinical management of TGCTs
Brain fatty acid synthase activates PPARa to maintain energy homeostasis
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
<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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