28,716 research outputs found
An application of statistics in mixture of exponential distributions
Order statistics in application to exponential distribution
An application of the multivariate extended Poisson distribution in 2 times 2 contingency tables Final report
Application of multivariate extended Poisson distribution
Evolution of Quantum Discord and its Stability in Two-Qubit NMR Systems
We investigate evolution of quantum correlations in ensembles of two-qubit
nuclear spin systems via nuclear magnetic resonance techniques. We use discord
as a measure of quantum correlations and the Werner state as an explicit
example. We first introduce different ways of measuring discord and geometric
discord in two-qubit systems and then describe the following experimental
studies: (a) We quantitatively measure discord for Werner-like states prepared
using an entangling pulse sequence. An initial thermal state with zero discord
is gradually and periodically transformed into a mixed state with maximum
discord. The experimental and simulated behavior of rise and fall of discord
agree fairly well. (b) We examine the efficiency of dynamical decoupling
sequences in preserving quantum correlations. In our experimental setup, the
dynamical decoupling sequences preserved the traceless parts of the density
matrices at high fidelity. But they could not maintain the purity of the
quantum states and so were unable to keep the discord from decaying. (c) We
observe the evolution of discord for a singlet-triplet mixed state during a
radio-frequency spin-lock. A simple relaxation model describes the evolution of
discord, and the accompanying evolution of fidelity of the long-lived singlet
state, reasonably well.Comment: 9 pages, 7 figures, Phys. Rev. A (in press
Immobilization by surface conjugation of cyclic peptides for effective mimicry of the HCV-envelope E2 protein as a strategy toward synthetic vaccines
Mimicry of the binding interface of antibody-antigen interactions using peptide-based modulators (i.e. epitope mimics) has promising applications for vaccine design. These epitope mimics can be synthesized in a streamlined and straightforward fashion, thereby allowing for high-throughput analysis. The design of epitope mimics is highly influenced by their spatial configuration and structural conformation. It is widely assumed that for proper mimicry sufficient conformational constraints have to be implemented. This paper describes the synthesis of bromide derivatives functional-ized with a flexible TEG linker equipped with a thiol-moiety that could be used to support cyclic or linear peptides. The cyclic and linear epitope mimics were covalently conjugated via the free thiol-moiety on maleimide-activated plate sur-faces. The resulting covalent, uniform, and oriented coated surface of cyclic or linear epitope mimics were subjected to an ELISA to investigate the effect of peptide cyclization with respect to mimicry of an antigen-antibody interaction of the HCV E2 glycoprotein. To our knowledge, the benefit of cyclized peptides over linear peptides has been clearly demon-strated here for the first time. Cyclic epitope mimics, and not the linear epitope mimics, demonstrated specificity towards their monoclonal antibodies HC84.1 and V3.2, respectively. The described strategy for the construction of epitope mimics shows potential for high-throughput screening of key-binding residues by simply changing the amino-acid sequences within synthetic peptides. In this way, leucine-438 has been identified as a key-binding residue for binding monoclonal antibody V3.2
Evolution of the far-infrared luminosity functions in the Spitzer Wide-area Infrared Extragalactic Legacy Survey
We present new observational determination of the evolution of the rest-frame
70 and 160 micron and total infrared (TIR) galaxy luminosity functions (LFs)
using 70 micron data from the Spitzer Wide-area Infrared Extragalactic Legacy
Survey (SWIRE). The LFs were constructed for sources with spectroscopic
redshifts only in the XMM-LSS and Lockman Hole fields from the SWIRE
photometric redshift catalogue. The 70 micron and TIR LFs were constructed in
the redshift range 0<z<1.2 and the 160 micron LF was constructed in the
redshift range 0<z<0.5 using a parametric Bayesian and the vmax methods. We
assume in our models, that the faint-end power-law index of the LF does not
evolve with redshifts. We find the the double power-law model is a better
representation of the IR LF than the more commonly used power-law and Gaussian
model. We model the evolution of the FIR LFs as a function of redshift where
where the characteristic luminosity, evolve as
\propto(1+z)^{\alpha_\textsc{l}}. The rest-frame 70 micron LF shows a strong
luminosity evolution out to z=1.2 with alpha_l=3.41^{+0.18}_{-0.25}. The
rest-frame 160 micron LF also showed rapid luminosity evolution with
alpha_l=5.53^{+0.28}_{-0.23} out to z=0.5. The rate of evolution in luminosity
is consistent with values estimated from previous studies using data from IRAS,
ISO and Spitzer. The TIR LF evolves in luminosity with
alpha_l=3.82^{+0.28}_{-0.16} which is in agreement with previous results from
Spitzer 24 micron which find strong luminosity evolution. By integrating the LF
we calculated the co-moving IR luminosity density out to z=1.2, which confirm
the rapid evolution in number density of LIRGs and ULIRGs which contribute
~68^{+10}_{-07} % to the co-moving star formation rate density at z=1.2. Our
results based on 70 micron data confirms that the bulk of the star formation at
z=1 takes place in dust obscured objects.Comment: 17 pages, 14 figure
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Melt conditioning by advanced shear technology (MCAST) for refining solidification microstructures
MCAST (melt conditioning by advanced shear technology) is a novel processing technology developed recently by BCAST at Brunel University for conditioning liquid metal prior to solidification processing. The MCAST process uses a twin screw mechanism to impose a high shear rate and a high intensity of turbulence to the liquid metal, so that the conditioned liquid metal has uniform temperature, uniform chemical composition and well-dispersed and completely wetted oxide particles with a fine size and a narrow size distribution. The microstructural refinement is achieved through an enhanced heterogeneous nucleation rate and an increased nuclei survival rate during the subsequent solidification processing. In this paper we present the MCAST process and its applications for microstructural refinement in both shape casting and continuous casting of light alloys
Analytic Element Method and Genetic Algorithm Based Models For Estimating Stream Bed Resistance
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
Weak-localization corrections to the conductivity of double quantum wells
The weak-localization contribution \delta\sigma(B) to the conductivity of a
tunnel-coupled double-layer electron system is evaluated and its behavior in
weak magnetic fields B perpendicular or parallel to the layers is examined. In
a perpendicular field B, \delta \sigma(B) increases and remains dependent on
tunneling as long as the magnetic field is smaller than \hbar/e D \tau_t, where
D is the in-plane diffusion coefficient and \tau_t the interlayer tunneling
time. If \tau_t is smaller than the inelastic scattering time, a parallel
magnetic field also leads to a considerable increase of the concuctivity
starting with a B**2 law and saturating at fields higher than \hbar/e Z (D
\tau_t)**(1/2), where Z is the interlayer distance. In the limit of coherent
tunneling, when \tau_t is comparable to elastic scattering time, \delta
\sigma(B) differs from that of a single-layer system due to ensuing
modifications of the diffusion coefficient. A possibility to probe the
weak-localization effect in double-layer systems by the dependence of the
conductivity on the gate-controlled level splitting is discussed.Comment: Text 18 pages in Latex/Revtex format, 4 Postscript figures. J. Phys.:
CM,in pres
An analysis on decentralized adaptive MAC protocols for Cognitive Radio networks
The scarcity of bandwidth in the radio spectrum has become more vital since the demand for more and more wireless applications has increased. Most of the spectrum bands have been allocated although many studies have shown that these bands are significantly underutilized most of the time. The problem of unavailability of spectrum and inefficiency in its utilization has been smartly addressed by the Cognitive Radio (CR) Technology which is an opportunistic network that senses the environment, observes the network changes, and then using knowledge gained from the prior interaction with the network, makes intelligent decisions by dynamically adapting their transmission characteristics. In this paper some of the decentralized adaptive MAC protocols for CR networks have been critically analyzed and a novel adaptive MAC protocol for CR networks, DNG-MAC which is decentralized and non-global in nature, has been proposed. The results show the DNG-MAC out performs other CR MAC protocols in terms of time and energy efficiency
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