Initiation of hepatitis C virus infection is dependent on cholesterol and cooperativity between CD81 and scavenger receptor B type I.

In the past several years, a number of cellular proteins have been identified as candidate entry receptors for hepatitis C virus (HCV) by using surrogate models of HCV infection. Among these, the tetraspanin CD81 and scavenger receptor B type I (SR-BI), both of which localize to specialized plasma membrane domains enriched in cholesterol, have been suggested to be key players in HCV entry. In the current study, we used a recently developed in vitro HCV infection system to demonstrate that both CD81 and SR-BI are required for authentic HCV infection in vitro, that they function cooperatively to initiate HCV infection, and that CD81-mediated HCV entry is, in part, dependent on membrane cholesterol

Investigating the impact of feedback update interval on the efficacy of restorative brain–computer interfaces

Restorative brain-computer interfaces (BCIs) have been proposed to enhance stroke rehabilitation. Restorative BCIs are able to close the sensorimotor loop by rewarding motor imagery (MI) with sensory feedback. Despite the promising results from early studies, reaching clinically significant outcomes in a timely fashion is yet to be achieved. This lack of efficacy may be due to suboptimal feedback provision. To the best of our knowledge, the optimal feedback update interval (FUI) during MI remains unexplored. There is evidence that sensory feedback disinhibits the motor cortex. Thus, in this study, we explore how shorter than usual FUIs affect behavioural and neurophysiological measures following BCI training for stroke patients using a single-case proof-of-principle study design. The action research arm test was used as the primary behavioural measure and showed a clinically significant increase (36%) over the course of training. The neurophysiological measures including motor evoked potentials and maximum voluntary contraction showed distinctive changes in early and late phases of BCI training. Thus, this preliminary study may pave the way for running larger studies to further investigate the effect of FUI magnitude on the efficacy of restorative BCIs. It may also elucidate the role of early and late phases of motor learning along the course of BCI training

TRIM63 (MuRF-1) Gene Polymorphism is Associated with Biomarkers of Exercise-Induced Muscle Damage

Unaccustomed strenuous exercise can lead to muscle strength loss, inflammation and delayed onset muscle soreness, which may be influenced by genetic variation. We investigated if a missense single nucleotide polymorphism (A>G, rs2275950) within the TRIM63 gene (encoding MuRF-1 and potentially affecting titin mechanical properties) was associated with the variable response to unaccustomed eccentric exercise. Sixty-five untrained, healthy participants (genotyped for rs2275950: AA, AG and GG) performed 120 maximal eccentric knee extensions (ECC) to induce muscle damage. Isometric and isokinetic maximal voluntary knee extension contractions (MVCs) and muscle soreness were assessed before, immediately after, and 48h after ECC. AA homozygotes were consistently stronger [baseline isometric MVC: 3.23±0.92 Nm/kg (AA) vs. 2.09±0.67 Nm/kg (GG); p=0.006] and demonstrated less muscle soreness over time (p=0.022) compared to GG homozygotes. This may be explained by greater titin stiffness in AA homozygotes, leading to intrinsically stronger muscle fibers that are more resistant to eccentric damaging contractions

Coherent strong-field control of multiple states by a single chirped femtosecond laser pulse

We present a joint experimental and theoretical study on strong-field photo-ionization of sodium atoms using chirped femtosecond laser pulses. By tuning the chirp parameter, selectivity among the population in the highly excited states 5p, 6p, 7p and 5f, 6f is achieved. Different excitation pathways enabling control are identified by simultaneous ionization and measurement of photoelectron angular distributions employing the velocity map imaging technique. Free electron wave packets at an energy of around 1 eV are observed. These photoelectrons originate from two channels. The predominant 2+1+1 Resonance Enhanced Multi-Photon Ionization (REMPI) proceeds via the strongly driven two-photon transition $4s\leftarrow\leftarrow3s$, and subsequent ionization from the states 5p, 6p and 7p whereas the second pathway involves 3+1 REMPI via the states 5f and 6f. In addition, electron wave packets from two-photon ionization of the non-resonant transiently populated state 3p are observed close to the ionization threshold. A mainly qualitative five-state model for the predominant excitation channel is studied theoretically to provide insights into the physical mechanisms at play. Our analysis shows that by tuning the chirp parameter the dynamics is effectively controlled by dynamic Stark-shifts and level crossings. In particular, we show that under the experimental conditions the passage through an uncommon three-state "bow-tie" level crossing allows the preparation of coherent superposition states

Complete Solving for Explicit Evaluation of Gauss Sums in the Index 2 Case

Let $p$ be a prime number, $q=p^f$ for some positive integer $f$, $N$ be a positive integer such that $\gcd(N,p)=1$, and let \k be a primitive multiplicative character of order $N$ over finite field \fq. This paper studies the problem of explicit evaluation of Gauss sums in "\textsl{index 2 case}" (i.e. f=\f{\p(N)}{2}=[\zn:\pp], where \p(\cd) is Euler function). Firstly, the classification of the Gauss sums in index 2 case is presented. Then, the explicit evaluation of Gauss sums G(\k^\la) (1\laN-1) in index 2 case with order $N$ being general even integer (i.e. N=2^{r}\cd N_0 where $r,N_0$ are positive integers and $N_03$ is odd.) is obtained. Thus, the problem of explicit evaluation of Gauss sums in index 2 case is completely solved

Coherent Optimal Control of Multiphoton Molecular Excitation

We give a framework for molecular multiphoton excitation process induced by an optimally designed electric field. The molecule is initially prepared in a coherent superposition state of two of its eigenfunctions. The relative phase of the two superposed eigenfunctions has been shown to control the optimally designed electric field which triggers the multiphoton excitation in the molecule. This brings forth flexibility in desiging the optimal field in the laboratory by suitably tuning the molecular phase and hence by choosing the most favorable interfering routes that the system follows to reach the target. We follow the quantum fluid dynamical formulation for desiging the electric field with application to HBr molecule.Comment: 5 figure