Do Balance Demands Induce Shifts in Visual Proprioception in Crawling Infants?

The onset of hands-and-knees crawling during the latter half of the first year of life heralds pervasive changes in a range of psychological functions. Chief among these changes is a clear shift in visual proprioception, evident in the way infants use patterns of optic flow in the peripheral field of view to regulate their postural sway. This shift is thought to result from consistent exposure in the newly crawling infant to different patterns of optic flow in the central field of view and the periphery and the need to concurrently process information about self-movement, particularly postural sway, and the environmental layout during crawling. Researchers have hypothesized that the demands on the infant's visual system to concurrently process information about self-movement and the environment press the infant to differentiate and functionalize peripheral optic flow for the control of balance during locomotion so that the central field of view is freed to engage in steering and monitoring the surface and potentially other tasks. In the current experiment, we tested whether belly crawling, a mode of locomotion that places negligible demands on the control of balance, leads to the same changes in the functional utilization of peripheral optic flow for the control of postural sway as hands-and-knees crawling. We hypothesized that hands-and-knees crawlers (n = 15) would show significantly higher postural responsiveness to movements of the side walls and ceiling of a moving room than same-aged pre-crawlers (n = 19) and belly crawlers (n = 15) with an equivalent amount of crawling experience. Planned comparisons confirmed the hypothesis. Visual-postural coupling in the hands-and-knees crawlers was significantly higher than in the belly crawlers and pre-crawlers. These findings suggest that the balance demands associated with hands-and-knees crawling may be an important contributor to the changes in visual proprioception that have been demonstrated in several experiments to follow hands-and-knees crawling experience. However, we also consider that belly crawling may have less potent effects on visual proprioception because it is an effortful and attention-demanding mode of locomotion, thus leaving less attentional capacity available to notice changing relations between the self and the environment

Partial and macroscopic phase coherences in underdoped Bi2{}_{2}Sr2{}_{2}CaCu2{}_{2}O8+δ{}_{8+{\delta}} thin film

A combined study with use of time-domain pump-probe spectroscopy and time-domain terahertz transmission spectroscopy have been carried out on an underdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+{\delta}}$ thin film. It was observed that the low energy multi-excitation states were decomposed into superconducting gap and pseudogap. The pseudogap locally opens below $T^*{\simeq}210$ K simultaneously with the appearance of the high-frequency partial pairs around 1.3 THz. With decreasing temperature, the number of the local domains with the partial phase coherence increased and saturated near 100 K, and the macroscopic superconductivity appeared below 76 K through the superconductivity fluctuation state below 100 K. These experimental results indicate that the pseudogap makes an important role for realization of the superconductivity as a precursor to switch from the partial to the macroscopic phase coherence.Comment: Revtex4, 4 pages, 4 figure

Global exponential convergence to variational traveling waves in cylinders

We prove, under generic assumptions, that the special variational traveling wave that minimizes the exponentially weighted Ginzburg-Landau functional associated with scalar reaction-diffusion equations in infinite cylinders is the long-time attractor for the solutions of the initial value problems with front-like initial data. The convergence to this traveling wave is exponentially fast. The obtained result is mainly a consequence of the gradient flow structure of the considered equation in the exponentially weighted spaces and does not depend on the precise details of the problem. It strengthens our earlier generic propagation and selection result for "pushed" fronts.Comment: 23 page

Inverse Compton emission from relativistic jets in binary systems

The gamma-ray emission detected from several microquasars can be produced by relativistic electrons emitting through inverse Compton scattering. In particular, the GeV emission detected from Cygnus X-3, and its orbital phase dependence, strongly suggests that the emitting electrons are accelerated in a relativistic jet, and that the optical companion provides the dominant target. Here, we study the effects related to particle transport in the framework of the relativistic jet scenario. We find that even in the most compact binary systems, with parameters similar to Cygnus X-3, particle transport can have a substantial influence on the GeV light curve unless the jet is slow, β < 0.7. In more extended binary systems, strong impact of particle transport is nearly unavoidable. Thus, even for a very compact system such as Cygnus X-3, particle transport significantly affects the ability of one-zone models to infer the properties of the gamma-ray production site based on the shape of the GeV lightcurve. We conclude that a detailed study of the gamma-ray spectrum can further constrain the structure and other properties of the gamma-ray emitter in Cygnus X-3, although such a study should account for gamma-gamma attenuation, since it may strongly affect the spectrum above 5GeV⁠

Direct observation of quantized interlayer vortex flow and vortex pinning distribution in high-Tc La_(1.87)Sr_(0.13)CuO_4 single crystals

A scanning superconducting quantum interference device (SQUID) microscope (SSM) is used to study the magnetic imaging of dynamic motion of quantized interlayer vortices induced by the Lorentz force in anisotropic high-Tc La_(1.87)Sr_(0.13)CuO_4 single crystals. It is found that 3 modes of flux motion switch depending on the transport current. By increasing the current a transition from the creep-like behavior of vortices to a steady flow of vortices was observed. Even higher current induced a continuous expansion of vortex-flow area indicating an inhomogeneous distribution of various pinning centers.Comment: 16 pages, 4 figure

Magnetic excitations in coupled Haldane spin chains near the quantum critical point

Two quasi-1-dimensional S=1 quantum antiferromagnetic materials, PbNi2V2O8 and SrNi2V2O8, are studied by inelastic neutron scattering on powder samples. While magnetic interactions in the two systems are found to be very similar, subtle differences in inter-chain interaction strengths and magnetic anisotropy are detected. The latter are shown to be responsible for qualitatively different ground state properties: magnetic long-range order in SrNi2V2O8 and disordered ``spin liquid'' Haldane-gap state in PbNi2V2O8.Comment: 15 figures, Figs. 5,9, and 10 in color. Some figures in JPEG format. Complete PostScript and PDF available from http://papillon.phy.bnl.gov/publicat.ht

The role of p16-cyclin D/CDK-pRb pathway in the tumorigenesis of endometrioid-type endometrial carcinoma

We analysed p16 gene alteration and p16, cyclin-dependent kinase 4 (CDK4), CDK6, cyclin D1, cyclin D2, cyclin D3 and retinoblastoma protein (pRb) expression in ten normal endometriums (PE), 18 endometrial hyperplasias (EH) and 35 endometrial cancers (EC). Two of ten PE (20%), nine of 18 EH (50.0%) and 29 of 35 EC (82.9%) exhibited p16 nuclear staining. p16 expression was significantly higher in EC than EH (P = 0.0119). In the six p16 (–) EC, one was considered to have reduced gene dosage consistent with possible homozygous deletion of the CDKN2 gene and three had methylation in 5′CpG island in the promoter region of the p16 gene, whereas none showed such reduced gene dosage and four had methylation in the nine p16 (–) EH. Strong CDK4 staining was observed in 12 of 35 EC (34.3%) and one of 18 EH (5.6%). The strong expression of CDK4 was higher in EC than in EH (P = 0.0399). The expression of CDK4 was higher in EH than PE (P = 0.0054). The abnormalities of p16-cyclin D/CDK-pRb pathway were detected in 18 of 35 EC (51.4%). In conclusion, the expression of p16 and CDK4 may be an early event in the neoplastic transformation of endometrial cancer. © 2000 Cancer Research Campaig

Fermi Large Area Telescope Observations of the Cygnus Loop Supernova Remnant

We present an analysis of the gamma-ray measurements by the Large Area Telescope(LAT) onboard the \textit{Fermi Gamma-ray Space Telescope} in the region of the supernova remnant(SNR) Cygnus Loop(G74.0$-$8.5). We detect significant gamma-ray emission associated with the SNR in the energy band 0.2--100 GeV. The gamma-ray spectrum shows a break in the range 2--3 GeV. The gamma-ray luminosity is $\sim$ $1 \times 10^{33}$erg s$^{-1}$ between 1--100 GeV, much lower than those of other GeV-emitting SNRs. The morphology is best represented by a ring shape, with inner/outer radii 0$^\circ$.7 $\pm$ 0$^\circ$.1 and 1$^\circ$.6 $\pm$ 0$^\circ$.1. Given the association among X-ray rims, \halpha filaments and gamma-ray emission, we argue that gamma rays originate in interactions between particles accelerated in the SNR and interstellar gas or radiation fields adjacent to the shock regions. The decay of neutral pions produced in nucleon-nucleon interactions between accelerated hadrons and interstellar gas provides a reasonable explanation for the gamma-ray spectrum.Comment: accepted by ApJ, 34 pages, 6 figure

One-loop surface tensions of (supersymmetric) kink domain walls from dimensional regularization

We consider domain walls obtained by embedding the 1+1-dimensional $\phi^4$-kink in higher dimensions. We show that a suitably adapted dimensional regularization method avoids the intricacies found in other regularization schemes in both supersymmetric and non-supersymmetric theories. This method allows us to calculate the one-loop quantum mass of kinks and surface tensions of kink domain walls in a very simple manner, yielding a compact d-dimensional formula which reproduces many of the previous results in the literature. Among the new results is the nontrivial one-loop correction to the surface tension of a 2+1 dimensional N=1 supersymmetric kink domain wall with chiral domain-wall fermions.Comment: 23 pages, LATeX; v2: 25 pages, 2 references added, extended discussion of renormalization schemes which dispels apparent contradiction with previous result

Origin of TeV Galactic Cosmic Rays

We consider a possibility of identification of sources of cosmic rays (CR) of the energy above 1 TeV via observation of degree-scale extended gamma-ray emission which traces the locations of recent sources in the Galaxy. Such emission in the energy band above 100 GeV is produced by CR nuclei and electrons released by the sources and spreading into the interstellar medium. We use the data from the Fermi gamma-ray telescope to locate the degree-scale 100 GeV gamma-ray sources. We find that the number of such sources and their overall power match to those expected when CRs injection events happen every ~100 yr in portions of ~1e50 erg. We find that most of the sources are associated to pulsars with spin down age less than ~30 kyr and hence to the recent supernova explosions. This supports the hypothesis of supernova origin of Galactic CRs. We notice that the degree-scale extended emission does not surround shell-like supernova remnants without pulsars. Based on this observation, we argue that the presence of the pulsar is essential for the CR acceleration process. We expect that a significant fraction of the degree-scale sources should be detectable as extended sources with km3-scale neutrino detectors.Comment: 14 pages, 14 figures, accepted for publication in Phys.Rev.