1,141 research outputs found
Symmetries and transport in site-dependently driven quantum lattices
We explore the quantum dynamics of particles in a spatiotemporally driven
lattice. A powerful numerical scheme is developed, which provides us with the
Floquet modes and thus enables a stroboscopic propagation of arbitrary initial
states. A detailed symmetry analysis represents the cornerstone for an
intricate manipulation of the Floquet spectrum. Specifically, we show how exact
crossings can be converted into avoided ones, while the width of these
resulting avoided crossings can be engineered by adjusting parameters of the
local driving. Asymptotic currents are shown to be controllable over a certain
parameter range
Analysis of interface conversion processes of ballistic and diffusive motion in driven superlattices
We explore the non-equilibrium dynamics of non-interacting classical
particles in a one-dimensional driven superlattice which is composed of domains
exposed to different time-dependent forces. It is shown how the combination of
directed transport and conversion processes from diffusive to ballistic motion
causes strong correlations between velocity and phase for particles passing
through a superlattice. A detailed understanding of the underlying mechanism
allows us to tune the resulting velocity distributions at distinguished points
in the superlattice by means of local variations of the applied driving force.
As an intriguing application we present a scheme how initially diffusive
particles can be transformed into a monoenergetic pulsed particle beam whose
parameters such as its energy can be varied
Mini-Collagens in Hydra Nematocytes
We have isolated and characterized four collagen-related c-DNA clones (N-COL 1, N-COL 2, N-COL 3, N-COL 4) that are highly expressed in developing nematocytes in hydra. All four c-DNAs as well as their corresponding transcripts are small in size (600-1,000 bp). The deduced amino acid sequences show that they contain a central region consisting of 14 to 16 Gly-X-Y triplets. This region is flanked amino-terminal by a stretch of 14-23 proline residues and carboxy-terminal by a stretch of 6-9 prolines. At the NH2- and COOH-termini are repeated patterns of cysteine residues that are highly conserved between the molecules. A model is proposed which consists of a central stable collagen triple helix of 12-14 nm length from which three 9-22 nm long polyproline II type helices emerge at both ends. Disulfide linkage between cysteine- rich segments in these helices could lead to the formation of oligomeric network structures. Electrophoretic characterization of nematocyst extracts allows resolution of small proline-rich polypeptides that correspond in size to the cloned sequences
Botulinum Toxin as Preventive Treatment for Migraine: A Randomized Double-Blind Study
Aim: To determine if botulinum toxin type A (BoNT-A) injections can reduce the frequency and severity of migraines. Methods: Patients (n = 127) were randomized to receive placebo or two doses of BoNT-A (Dysport (R)). The primary endpoint was reduction in number of migraine attacks up to week 8 and between weeks 8 and 12 after injection. Patient diaries were used to record secondary endpoints, including frequency, severity and duration of migraine attacks. Results: There was a mean reduction of 0.54 and 0.94 attacks/month with placebo and BoNT-A, respectively, and absolute attack count was less in the verum group (3.6 vs. 4.2 attacks/month), but this was not statistically significant. The patients' global assessment of efficacy was significantly better than placebo in the high-dose group (p = 0.02) but no effects were seen for the other secondary efficacy parameters. Conclusion: Our study showed a trend towards a reduced attack rate with verum but did not show any statistically significant efficacy of BoNT-A in the prophylactic treatment of migraine. Copyright (C) 2009 S. Karger AG, Base
Feasibility of ultra-performance liquid chromatography-ion mobility-time-of-flight mass spectrometry in analyzing oxysterols
Oxysterols are oxygenated cholesterols that are important in many cell functions and they may also be indicative of certain diseases. The purpose of this work was to study the feasibility of ultra-performance liquid chromatography-ion mobility-time-of-flight mass spectrometry (UPLC-IM-TOFMS) using traveling wave cell in analyzing oxysterols and especially their isomers in biological samples. Oxysterols were analyzed as their p-toluenesulfonyl isocyanate derivatives, which improved the separation of isomeric oxysterols by ion mobility and ionization efficiency in the electrospray ionization step. The UPLC-IM-TOFMS method was shown to be fast and to provide good quantitative performance. The feasibility of the method was demonstrated in the analyses of oxysterols in fibroblast cell samples. (C) 2017 Elsevier B.V. All rights reserved.Peer reviewe
On the minimal diameter of closed hyperbolic surfaces
We prove that the minimal diameter of a hyperbolic compact orientable surface
of genus is asymptotic to as . The proof relies on a
random construction, which we analyse using lattice point counting theory and
the exploration of random trivalent graphs.Comment: 9 pages, 4 figure
Learning Automata and Transducers: A Categorical Approach
In this paper, we present a categorical approach to learning automata over words, in the sense of the L*-algorithm of Angluin. This yields a new generic L*-like algorithm which can be instantiated for learning deterministic automata, automata weighted over fields, as well as subsequential transducers. The generic nature of our algorithm is obtained by adopting an approach in which automata are simply functors from a particular category representing words to a "computation category". We establish that the sufficient properties for yielding the existence of minimal automata (that were disclosed in a previous paper), in combination with some additional hypotheses relative to termination, ensure the correctness of our generic algorithm
Management of collaborative BIM data by the Federatinon of Distributed Models
The architecture engineering and construction sector is currently undergoing a significant period of change and modernization. In the United Kingdom in particular this is driven by the government’s objective of reducing the cost of construction projects. This is to be achieved by requiring all publicly funded projects to utilize fully collaborative building information modeling by 2016. A common goal in increasing building information model (BIM) adoption by the industry is the movement toward the realization of a BIM as either a single data model or a series of tightly coupled federated models. However, there are key obstacles to be overcome, including uncertainty over data ownership, concerns relating to the security/privacy of data, and reluctance to “outsource” data storage. This paper proposes a framework that is able to provide a solution for managing collaboration in the architecture engineering and construction (AEC) sector. The solution presented in this paper provides an overlay that automatically federates and governs distributed BIM data. The use of this overlay provides an integrated BIM model that is physically distributed across the stakeholders in a construction project. The key research question addressed by this paper is whether such an overlay can, by providing dynamic federation and governance of BIM data, overcome some key obstacles to BIM adoption, including questions over data ownership, the security/privacy of data, and reluctance to share data. More specifically, this paper provides the following contributions: (1) presentation of a vision for the implementation and governance of a federated distributed BIM data model; (2) description of the BIM process and governance model that underpins the approach; (3) provision of a validation case study using real construction data from a U.K. highways project, demonstrating that both the federated BIM overlay and the process and governance model are fit for purpose. - See more at: http://ascelibrary.org/doi/full/10.1061/(ASCE)CP.1943-5487.0000657#sthash.jIj574Lh.dpu
Performance analysis of multi-institutional data sharing in the Clouds4Coordination system
Cloud computing is used extensively in Architecture/ Engineering/ Construction projects for storing data and running simulations on building models (e.g. energy efficiency/environmental impact). With the emergence of multi-Clouds it has become possible to link such systems and create a distributed cloud environment. A multi-Cloud environment enables each organisation involved in a collaborative project to maintain its own computational infrastructure/ system (with the associated data), and not have to migrate to a single cloud environment. Such infrastructure becomes efficacious when multiple individuals and organisations work collaboratively, enabling each individual/ organisation to select a computational infrastructure that most closely matches its requirements. We describe the “Clouds-for-Coordination” system, and provide a use case to demonstrate how such a system can be used in practice. A performance analysis is carried out to demonstrate how effective such a multi-Cloud system can be, reporting “aggregated-time-to-complete” metric over a number of different scenarios
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