1,520 research outputs found

    Localization in momentum space of ultracold atoms in incommensurate lattices

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    We characterize the disorder induced localization in momentum space for ultracold atoms in one-dimensional incommensurate lattices, according to the dual Aubry-Andr\'e model. For low disorder the system is localized in momentum space, and the momentum distribution exhibits time-periodic oscillations of the relative intensity of its components. The behavior of these oscillations is explained by means of a simple three-mode approximation. We predict their frequency and visibility by using typical parameters of feasible experiments. Above the transition the system diffuses in momentum space, and the oscillations vanish when averaged over different realizations, offering a clear signature of the transition

    The Enzymatic Activity and Molecular Characterization of a Secreted Subtilisin-Like Protease in Microsporum gypseum and Trichophyton vanbreuseghemii

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    Background: Subtilisin -like proteases are the group of proteases including keratinases found in dermatophytes which de­graded keratin. Determination of the proteases activity of Trichophyton vanbreuseghemii isolates which were obtained from soil and clinical and soil isolates of Microsporum gypseum in Iran and characterization of their genome were aim of present study.Methods: Ezymatic activity was determined by use of chromogenic substrates. The genes, which coded subtilisin-like pro­teases in above-mentioned dermatophytes, was identified and amplified by using specific primers in PCR. Results: The highest yield of enzyme production was observed in only one isolate of T. vanbreuseghemii Ir-84 whereas low enzyme activity was observed in M. gypseum isolates. Homology study of obtained nucleotide as well as amino acid sequences indicated different rates of homology with other subtilisin-like proteases genes in other pathogenic dermato­phytes. Conclusion: Intra-strain differences were observed in production of serine proteinases and molecular characterization of genes encoding such enzymes could be of great interest for studies on pathogenicity and other purposes

    Nonlinear Lattice Waves in Random Potentials

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    Localization of waves by disorder is a fundamental physical problem encompassing a diverse spectrum of theoretical, experimental and numerical studies in the context of metal-insulator transition, quantum Hall effect, light propagation in photonic crystals, and dynamics of ultra-cold atoms in optical arrays. Large intensity light can induce nonlinear response, ultracold atomic gases can be tuned into an interacting regime, which leads again to nonlinear wave equations on a mean field level. The interplay between disorder and nonlinearity, their localizing and delocalizing effects is currently an intriguing and challenging issue in the field. We will discuss recent advances in the dynamics of nonlinear lattice waves in random potentials. In the absence of nonlinear terms in the wave equations, Anderson localization is leading to a halt of wave packet spreading. Nonlinearity couples localized eigenstates and, potentially, enables spreading and destruction of Anderson localization due to nonintegrability, chaos and decoherence. The spreading process is characterized by universal subdiffusive laws due to nonlinear diffusion. We review extensive computational studies for one- and two-dimensional systems with tunable nonlinearity power. We also briefly discuss extensions to other cases where the linear wave equation features localization: Aubry-Andre localization with quasiperiodic potentials, Wannier-Stark localization with dc fields, and dynamical localization in momentum space with kicked rotors.Comment: 45 pages, 19 figure

    Highlighting type A RRs as potential regulators of the dkHK1 multi-step phosphorelay pathway in Populus

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    In previous studies, we highlighted a multistep phosphorelay (MSP) system in poplars composed of two hybrid-type Histidine aspartate Kinases, dkHK1a and dkHK1b, which interact with three Histidine Phosphotransfer proteins, dkHPt2, 7, and 9, which in turn interact with six type B Response Regulators. These interactions correspond to the dkHK1a-b/dkHPts/dkRRBs MSP. This MSP is putatively involved in an osmosensing pathway, as dkHK1a-b are orthologous to the Arabidopsis osmosensor AHK1, and able to complement a mutant yeast deleted for its osmosensors. Since type A RRs have been characterized as negative regulators in cytokinin MSP signaling due to their interaction with HPt proteins, we decided in this study to characterize poplar type A RRs and their implication in the MSP. For a global view of this MSP, we isolated 10 poplar type A RR cDNAs, and determined their subcellular localization to check the in silico prediction experimentally. For most of them, the in planta subcellular localization was as predicted, except for three RRAs, for which this experimental approach gave a more precise localization. Interaction studies using yeast two-hybrid and in planta BiFC assays, together with transcript expression analysis in poplar organs led to eight dkRRAs being singled out as partners which could interfere the dkHK1a-b/dkHPts/dkRRBs MSP identified in previous studies. Consequently, the results obtained in this study now provide an exhaustive view of dkHK1a-b partners belonging to a poplar MSP

    On sequences with prescribed metric discrepancy behavior

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    Human Monoclonal Antibodies Neutralizing Cytomegalovirus (CMV) for Prophylaxis of CMV Disease: Report of a Phase I Trial in Bone Marrow Transplant Recipients

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    The safety and pharmacokinetics of the two neutralizing human IgG1 monoclonal antibodies to cytomegalovirus (CMV) SDZ89-104 and 89-109 in bonemarrowtransplant (BM1)recipients was assessed in an open phase I trial. Thirteen patients, 8 seropositive and 5 seronegative for CMV, were treated with allogeneic or autologous bone marrow transplantation. SDZ 89-104 was given to 5 and SDZ 89-109 to 8 patients. Patients were divided into high-and low-dose groups. A fixed prestudy dose of 0.1 mg/kg was given 4 days before BMT. On days 3, 17, 31,45, 59, and 73, patients were treated with either 0.5 or 2 mg/kg of the respective antibody. Results indicate that doses of 2 mg/kg of SDZ 89-104 or SDZ 89-109 in alternating weeks can be safely administered to BMT patients. Serum trough levels measured by antiidiotype ELISA were ∼10 µg/ml after administration of 0.5 mg/kg and ∼50 µg/ml after treatment with 2 mg/kg of SDZ 89-104 or SDZ 89-109. High serum levels defined by antiidiotype ELISA techniques closely paralleled increased neutralizing activity. Serum half-lives calculatedfrom these data were ∼6 day

    Gas valves, forests and global change: a commentary on Jarvis (1976) 'The interpretation of the variations in leaf water potential and stomatal conductance found in canopies in the field'.

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    Microscopic turgor-operated gas valves on leaf surfaces-stomata-facilitate gas exchange between the plant and the atmosphere, and respond to multiple environmental and endogenous cues. Collectively, stomatal activities affect everything from the productivity of forests, grasslands and crops to biophysical feedbacks between land surface vegetation and climate. In 1976, plant physiologist Paul Jarvis reported an empirical model describing stomatal responses to key environmental and plant conditions that predicted the flux of water vapour from leaves into the surrounding atmosphere. Subsequent theoretical advances, building on this earlier approach, established the current paradigm for capturing the physiological behaviour of stomata that became incorporated into sophisticated models of land carbon cycling. However, these models struggle to accurately predict observed trends in the physiological responses of Northern Hemisphere forests to recent atmospheric CO2 increases, highlighting the need for improved representation of the role of stomata in regulating forest-climate interactions. Bridging this gap between observations and theory as atmospheric CO2 rises and climate change accelerates creates challenging opportunities for the next generation of physiologists to advance planetary ecology and climate science. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society

    Transport by molecular motors in the presence of static defects

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    The transport by molecular motors along cytoskeletal filaments is studied theoretically in the presence of static defects. The movements of single motors are described as biased random walks along the filament as well as binding to and unbinding from the filament. Three basic types of defects are distinguished, which differ from normal filament sites only in one of the motors' transition probabilities. Both stepping defects with a reduced probability for forward steps and unbinding defects with an increased probability for motor unbinding strongly reduce the velocities and the run lengths of the motors with increasing defect density. For transport by single motors, binding defects with a reduced probability for motor binding have a relatively small effect on the transport properties. For cargo transport by motors teams, binding defects also change the effective unbinding rate of the cargo particles and are expected to have a stronger effect.Comment: 20 pages, latex, 7 figures, 1 tabl

    Point sets on the sphere S2\mathbb{S}^2 with small spherical cap discrepancy

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    In this paper we study the geometric discrepancy of explicit constructions of uniformly distributed points on the two-dimensional unit sphere. We show that the spherical cap discrepancy of random point sets, of spherical digital nets and of spherical Fibonacci lattices converges with order N−1/2N^{-1/2}. Such point sets are therefore useful for numerical integration and other computational simulations. The proof uses an area-preserving Lambert map. A detailed analysis of the level curves and sets of the pre-images of spherical caps under this map is given

    I4U Submission to NIST SRE 2018: Leveraging from a Decade of Shared Experiences

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    The I4U consortium was established to facilitate a joint entry to NIST speaker recognition evaluations (SRE). The latest edition of such joint submission was in SRE 2018, in which the I4U submission was among the best-performing systems. SRE'18 also marks the 10-year anniversary of I4U consortium into NIST SRE series of evaluation. The primary objective of the current paper is to summarize the results and lessons learned based on the twelve sub-systems and their fusion submitted to SRE'18. It is also our intention to present a shared view on the advancements, progresses, and major paradigm shifts that we have witnessed as an SRE participant in the past decade from SRE'08 to SRE'18. In this regard, we have seen, among others, a paradigm shift from supervector representation to deep speaker embedding, and a switch of research challenge from channel compensation to domain adaptation.Comment: 5 page
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