Determining Shared Working Memory Systems for Rhythmic Incongruities in Music and Language using functional Near-Infrared Spectroscopy

Rhythmic organization of auditory information is used differently in the retention of music and spoken language. However, similar areas of the prefrontal cortex (PFC) have been implicated in the retention of unusual rhythmic patterns. This study investigated the degree of PFC activation using functional near-infrared spectroscopy (fNIRS) during three rhythmic pattern manipulation working memory tasks. In addition the normalized pair-wise variability index (NPVI) was tested as a measure of rhythmic accuracy. Of the six participants considered, three demonstrated greater activation of the right PFC in response to the Rhythmic Motor task, a manipulation of musical rhythms. Similar activation was observed for the Stress Speech task, which altered stress patterns in natural speech. No changes in activation were observed in the Rhythmic Speech task, which paired speech with metric patterns. The NPVI values did not reflect task performance. Refinement is needed to determine if the current procedure accurately measures rhythmic working memory

Imaging density disturbances in water with 41.3 attosecond time resolution

We show that the momentum flexibility of inelastic x-ray scattering may be exploited to invert its loss function, alowing real time imaging of density disturbances in a medium. We show the disturbance arising from a point source in liquid water, with a resolution of 41.3 attoseconds ($4.13 \times 10^{-17}$ sec) and 1.27 $\AA$ ($1.27 \times 10^{-8}$ cm). This result is used to determine the structure of the electron cloud around a photoexcited molecule in solution, as well as the wake generated in water by a 9 MeV gold ion. We draw an analogy with pump-probe techniques and suggest that energy-loss scattering may be applied more generally to the study of attosecond phenomena.Comment: 4 pages, 4 color figure

Eigen modes for the problem of anomalous light transmission through subwavelength holes

We show that the wide-spread concept of optical eigen modes in lossless waveguide structures, which assumes the separation on propagating and evanescent modes, fails in the case of metal-dielectric structures, including photonic crystals. In addition to these modes, there is a sequence of new eigen-states with complex values of the propagation constant and non-vanishing circulating energy flow. The whole eigen-problem ceases to be hermitian because of changing sign of the optical dielectric constant. The new anomalous modes are shown to be of prime importance for the description of the anomalous light transmission through subwavelength holes.Comment: 5 pages, 4 figure

Risk factors for severe acute lower respiratory infections in children – a systematic review and meta-analysis

Aim To identify the risk factors in children under five years of age for severe acute lower respiratory infections (ALRI), which are the leading cause of child mortality. Methods We performed a systematic review of published literature available in the public domain. We conducted a quality assessment of all eligible studies according to GRADE criteria and performed a meta-analysis to report the odds ratios for all risk factors identified in these studies. Results We identified 36 studies that investigated 19 risk factors for severe ALRI. Of these, 7 risk factors were significantly associated with severe ALRI in a consistent manner across studies, with the following meta-analysis estimates of odds ratios (with 95% confidence intervals): low birth weight 3.18 (1.02-9.90), lack of exclusive breastfeeding 2.34 (1.42-3.88), crowding – more than 7 persons per household 1.96 (1.53-2.52), exposure to indoor air pollution 1.57 (1.06-2.31), incomplete immunization 1.83 (1.32-2.52), undernutrition – weight-for-age less than 2 standard deviations 4.47 (2.10-9.49), and HIV infection 4.15 (2.57-9.74). Conclusion This study highlights the role of the above seven risk factors in the development of severe pneumonia in under-five children. In addition, it emphasizes the need for further studies investigating other potential risk factors. Since these risk factors are potentially preventable, health policies targeted at reducing their prevalence provide a basis for decreasing the burden of childhood pneumonia

Multipole structure and coordinate systems

Multipole expansions depend on the coordinate system, so that coefficients of multipole moments can be set equal to zero by an appropriate choice of coordinates. Therefore, it is meaningless to say that a physical system has a nonvanishing quadrupole moment, say, without specifying which coordinate system is used. (Except if this moment is the lowest non-vanishing one.) This result is demonstrated for the case of two equal like electric charges. Specifically, an adapted coordinate system in which the potential is given by a monopole term only is explicitly found, the coefficients of all higher multipoles vanish identically. It is suggested that this result can be generalized to other potential problems, by making equal coordinate surfaces coincide with the potential problem's equipotential surfaces.Comment: 2 figure

On the twist-2 contributions to polarized structure functions and new sum rules

The twist-2 contributions to the polarized structure functions in deep inelastic lepton--hadron scattering are calculated including the exchange of weak bosons and using both the operator product expansion and the covariant parton model. A new relation between two structure functions leading to a sequence of new sum rules is found. The light quark mass corrections to the structure functions are derived in lowest order QCD.Comment: 15 pages Latex, inclding five eps-figures, all compressed by uufile substituting the ps-file available befor

Scalar--Field Amplitudes in Black--Hole Evaporation

We study the quantum-mechanical decay of a Schwarzschild-like black hole into almost-flat space and weak radiation at a very late time, evaluating quantum amplitudes (not just probabilities) for transitions from initial to final states. No information is lost. The model contains gravity and a massless scalar field. The quantum amplitude to go from given initial to final bosonic data in a slightly complexified time-interval $T={\tau}{\exp}(-i{\theta})$ at infinity is approximately $\exp(-I)$, where $I$ is the (complex) Euclidean action of the classical solution filling in between the boundary data. And in a locally supersymmetric (supergravity) theory, the amplitude const. exp(-I) is exact. Dirichlet boundary data for gravity and the scalar field are posed on an initial spacelike hypersurface extending to spatial infinity, just prior to collapse, and on a corresponding final spacelike surface, sufficiently far to the future of the initial surface to catch all the Hawking radiation. In an averaged sense this radiation has an approximately spherically-symmetric distribution. If the time-interval $T$ were exactly real, the resulting `hyperbolic Dirichlet boundary-value problem' would not be well posed. If instead (`Euclidean strategy'), one takes $T$ complex, as above ($0<\theta{\leq}{\pi}/2$), the field equations become strongly elliptic, with a unique solution to the classical boundary-value problem. Expanding the bosonic part of the action to quadratic order in perturbations about the classical solution gives the quantum amplitude for weak-field final configurations, up to normalization. Such amplitudes are calculated for weak final scalar fields.Comment: Submitted to Physics Letters B, Friday 23rd July 200

A cloudy model for the Circumnuclear Disk in the Galactic Centre

We present a first attempt to construct an analytic model for a clumped gas and dust disk and apply it to the Galactic Centre. The clumps are described as isothermal spheres partially ionized by the external UV radiation field. The disk structure formed by the clouds is described as a quasi standard continuous accretion disk using adequately averaged parameters of the discrete cloud model. The viscosity in the Circumnuclear Disk is due to partially inelastic cloud-cloud collisions. We find two different solutions for the set of equations corresponding to two stable cloud regimes: (i) the observed molecular clouds and (ii) much lighter and smaller clouds which correspond to the stripped cores of the observed clouds. It is shown that the resulting physical characteristics of the heavy clouds and the disk are in very good agreement with all comparable observations at multiple wavelengths. A mass accretion rate of approx. 10^-4 M_solar/yr for the isolated Circumnuclear Disk is inferred. We propose that the Circumnuclear Disk has a much longer lifetime (approx. 10^7 yr) than previously assumed.Comment: 12 pages with 13 figures, A&A, in pres

Ribosome recycling, diffusion, and mRNA loop formation in translational regulation

We explore and quantify the physical and biochemical mechanisms that may be relevant in the regulation of translation. After elongation and detachment from the 3' termination site of mRNA, parts of the ribosome machinery can diffuse back to the initiation site, especially if it is held nearby, enhancing overall translation rates. The elongation steps of the mRNA-bound ribosomes are modeled using exact and asymptotic results of the totally asymmetric exclusion process (TASEP).Since the ribosome injection rates of the TASEP depend on the local concentrations at the initiation site, a source of ribosomes emanating from the termination end can feed back to the initiation site, leading to a self-consistent set of equations for the steady-state ribosome throughput. Additional mRNA binding factors can also promote loop formation, or cyclization, bringing the initiation and termination sites into close proximity. The probability distribution of the distance between the initiation and termination sites is described using simple noninteracting polymer models. We find that the initiation, or initial ribosome adsorption binding required for maximal throughput can vary dramatically depending on certain values of the bulk ribosome concentration and diffusion constant. If cooperative interactions among the loop-promoting proteins and the initiation/termination sites are considered, the throughput can be further regulated in a nonmonotonic manner. Potential experiments to test the hypothesized physical mechanisms are discussed.Comment: 21 pp, 11 .eps figs, realigned figures and magin

On the Twist 2 and Twist 3 Contributions to the Spin-dependent Electroweak Structure Functions

The twist 2 and twist 3 contributions of the polarized deep-inelastic structure functions are calculated both for neutral and charged current interactions using the operator product expansion in lowest order in QCD. The relations between the different structure functions are determined. New integral relations are derived between the twist 2 contributions of the structure functions $g_3(x,Q^2)$ and $g_5(x,Q^2)$ and between combinations of the twist 3 contributions to the structure functions $g_2(x,Q^2)$ and $g_3(x,Q^2)$. The sum rules for polarized deep inelastic scattering are discussed in detail.Comment: 24 pages plain Latex, some typographical errors correcte