335 research outputs found

    Energy evolution in time-dependent harmonic oscillator

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    The theory of adiabatic invariants has a long history, and very important implications and applications in many different branches of physics, classically and quantally, but is rarely founded on rigorous results. Here we treat the general time-dependent one-dimensional harmonic oscillator, whose Newton equation q¨+ω2(t)q=0\ddot{q} + \omega^2(t) q=0 cannot be solved in general. We follow the time-evolution of an initial ensemble of phase points with sharply defined energy E0E_0 at time t=0t=0 and calculate rigorously the distribution of energy E1E_1 after time t=Tt=T, which is fully (all moments, including the variance μ2\mu^2) determined by the first moment E1ˉ\bar{E_1}. For example, μ2=E02[(E1ˉ/E0)2(ω(T)/ω(0))2]/2\mu^2 = E_0^2 [(\bar{E_1}/E_0)^2 - (\omega (T)/\omega (0))^2]/2, and all higher even moments are powers of μ2\mu^2, whilst the odd ones vanish identically. This distribution function does not depend on any further details of the function ω(t)\omega (t) and is in this sense universal. In ideal adiabaticity E1ˉ=ω(T)E0/ω(0)\bar{E_1} = \omega(T) E_0/\omega(0), and the variance μ2\mu^2 is zero, whilst for finite TT we calculate E1ˉ\bar{E_1}, and μ2\mu^2 for the general case using exact WKB-theory to all orders. We prove that if ω(t)\omega (t) is of class Cm{\cal C}^{m} (all derivatives up to and including the order mm are continuous) μT(m+1)\mu \propto T^{-(m+1)}, whilst for class C{\cal C}^{\infty} it is known to be exponential μexp(αT)\mu \propto \exp (-\alpha T).Comment: 26 pages, 5 figure

    Simple classical groups of Lie type are determined by their character degrees

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    In this paper, we will show that nonabelian simple classical groups of Lie type are uniquely determined by the structure of their complex group algebras.Comment: 10 pages, to appear in Journal of Algebr

    Antibiotic-producing symbionts dynamically transition between plant pathogenicity and insect-defensive mutualism

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    Pathogenic and mutualistic bacteria associated with eukaryotic hosts often lack distinctive genomic features, suggesting regular transitions between these lifestyles. Here we present evidence supporting a dynamic transition from plant pathogenicity to insect-defensive mutualism in symbiotic Burkholderia gladioli bacteria. In a group of herbivorous beetles, these symbionts protect the vulnerable egg stage against detrimental microbes. The production of a blend of antibiotics by B. gladioli, including toxoflavin, caryoynencin and two new antimicrobial compounds, the macrolide lagriene and the isothiocyanate sinapigladioside, likely mediate this defensive role. In addition to vertical transmission, these insect symbionts can be exchanged via the host plant and retain the ability to initiate systemic plant infection at the expense of the plant’s fitness. Our findings provide a paradigm for the transition between pathogenic and mutualistic lifestyles and shed light on the evolution and chemical ecology of this defensive mutualism

    Insect‐associated bacteria assemble the antifungal butenolide gladiofungin by non‐canonical polyketide chain termination

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    Genome mining of one of the protective symbionts ( Burkholderia gladioli ) of the invasive beetle Lagria villosa revealed a cryptic gene cluster that codes for the biosynthesis of a novel antifungal polyketide with a glutarimide pharmacophore. Targeted gene inactivation, metabolic profiling, and bioassays led to the discovery of the gladiofungins as previously‐overlooked components of the antimicrobial armory of the beetle symbiont, which are highly active against the entomopathogenic fungus Purpureocillium lilacinum . By mutational analyses, isotope labeling, and computational analyses of the modular polyketide synthase, we found that the rare butenolide moiety of gladiofungins derives from an unprecedented polyketide chain termination reaction involving a glycerol‐derived C3 building block. The key role of an A‐factor synthase (AfsA)‐like offloading domain was corroborated by CRISPR‐Cas‐mediated gene editing, which facilitated precise excision within a PKS domain

    Author Correction: Cancer Testis Antigen Promotes Triple Negative Breast Cancer Metastasis and is Traceable in the Circulating Extracellular Vesicles (Scientific Reports, (2019), 9, 1, (11632), 10.1038/s41598-019-48064-w)

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    Triple negative breast cancer (TNBC) has poor survival, exhibits rapid metastases, lacks targeted therapies and reliable prognostic markers. Here, we examined metastasis promoting role of cancer testis antigen SPANXB1 in TNBC and its utility as a therapeutic target and prognostic biomarker. Expression pattern of SPANXB1 was determined using matched primary cancer, lymph node metastatic tissues and circulating small extracellular vesicles (sEVs). cDNA microarray analysis of TNBC cells stably integrated with a metastasis suppressor SH3GL2 identified SPANXB1 as a potential target gene. TNBC cells overexpressing SH3GL2 exhibited decreased levels of both SPANXB1 mRNA and protein. Silencing of SPANXB1 reduced migration, invasion and reactive oxygen species production of TNBC cells. SPANXB1 depletion augmented SH3GL2 expression and decreased RAC-1, FAK, A-Actinin and Vinculin expression. Phenotypic and molecular changes were reversed upon SPANXB1 re-expression. SPANXB1 overexpressing breast cancer cells with an enhanced SPANXB1:SH3GL2 ratio achieved pulmonary metastasis within 5 weeks, whereas controls cells failed to do so. Altered expression of SPANXB1 was detected in the sEVs of SPANXB1 transduced cells. Exclusive expression of SPANXB1 was traceable in circulating sEVs, which was associated with TNBC progression. SPANXB1 represents a novel and ideal therapeutic target for blocking TNBC metastases due to its unique expression pattern and may function as an EV based prognostic marker to improve TNBC survival. Uniquely restricted expression of SPANXB1 in TNBCs, makes it an ideal candidate for targeted therapeutics and prognostication

    Preparation of anti-vicinal amino alcohols: asymmetric synthesis of D-erythro-Sphinganine, (+)-spisulosine and D-ribo-phytosphingosine

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    Two variations of the Overman rearrangement have been developed for the highly selective synthesis of anti-vicinal amino alcohol natural products. A MOM-ether directed palladium(II)-catalyzed rearrangement of an allylic trichloroacetimidate was used as the key step for the preparation of the protein kinase C inhibitor D-erythro-sphinganine and the antitumor agent (+)-spisulosine, while the Overman rearrangement of chiral allylic trichloroacetimidates generated by asymmetric reduction of an alpha,beta-unsaturated methyl ketone allowed rapid access to both D-ribo-phytosphingosine and L-arabino-phytosphingosine

    Discovery of 3-Formyl-Tyrosine Metabolites from Pseudoalteromonas tunicata through Heterologous Expression

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    Genome mining and identification of natural product gene clusters typically relies on the presence of canonical nonribosomal polypeptide synthetase (NRPS) or polyketide synthase (PKS) domains. Recently, other condensation enzymes, such as the ATP-grasp ligases, have been recognized as important players in natural product biosynthesis. In this study, sequence based searching for homologues of DdaF, the ATP-grasp amide ligase from dapdiamide biosynthesis, led to the identification of a previously unannotated biosynthetic gene cluster in Pseudoalteromonas tunicata. Heterologous expression of the cluster in Escherichia coli allowed for the production and structure determination of two new 3-formyl tyrosine metabolites.Molecular and Cellular Biolog

    Randomized phase 1b trial of MOR103, a human antibody to GM-CSF, in multiple sclerosis

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    Objectives: To determine the safety, pharmacokinetics (PK), and immunogenicity of the recombinant human monoclonal antibody MOR103 to granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients with multiple sclerosis (MS) with clinical or MRI activity.Methods: In this 20-week, randomized, double-blind, placebo-controlled phase 1b dose-escalation trial (registration number NCT01517282), adults with relapsing-remitting MS (RRMS) or secondary progressive MS (SPMS) received an IV infusion of placebo (n = 6) or MOR103 0.5 (n = 8), 1.0 (n = 8), or 2.0 (n = 9) mg/kg every 2 weeks for 10 weeks. Patients had to have ≤10 gadolinium (Gd)-enhancing brain lesions on T1-weighted MRI at baseline. The primary objective was safety.Results: Most treatment-emergent adverse events (TEAEs) were mild to moderate in severity. The most frequent was nasopharyngitis. Between-group differences in TEAE numbers were small. There were no TEAE-related trial discontinuations, infusion-related reactions, or deaths. Nine patients experienced MS exacerbations: 3, 5, 1, and 0 patient(s) in the placebo, 0.5, 1.0, and 2.0 mg/kg groups, respectively. A few T1 Gd-enhancing lesions and/or new or enlarging T2 lesions indicative of inflammation were observed in all treatment groups. No clinically significant changes were observed in other clinical assessments or laboratory safety assessments. No anti-MOR103 antibodies were detected. PK evaluations indicated dose linearity with low/no drug accumulation over time.Conclusions: MOR103 was generally well-tolerated in patients with RRMS or SPMS. No evidence of immunogenicity was found.Classification of evidence: This phase 1b study provides Class I evidence that MOR103 has acceptable tolerability in patients with MS
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