A Canonical Ds(2317)?

It is shown that quark mass dependence induced by one loop corrections to the Breit-Fermi spin-dependent one gluon exchange potential permit an accurate determination of heavy-light meson masses. Thus the $D_s(2317)$ is a canonical $c\bar s$ meson in this scenario. The multiplet splitting relationship of chiral doublet models, $M(1^+)-M(1^-) = M(0^+) -M(0^-)$, holds to good accuracy in the $D$ and $D_s$ systems, but is accidental. Radiative transitions and bottom flavoured meson masses are discussed.Comment: 7 pages, 6 figures. References improve

Study of meson properties in quark models

The main motivation is to investigate meson properties in the quark model to understand the model applicability and generate possible improvements. Certain modifications to the model are suggested which have been inspired by fundamental QCD properties (such as running coupling or spin dependence of strong interactions). These modifications expand the limits of applicability of the constituent quark model and illustrate its weaknesses and strengths. The meson properties studied include meson spectra, decay constants, electromagnetic and electroweak form-factors and radiative transitions. The results are compared to the experimental data, lattice gauge theory calculations and other approaches

The Guidance of Olfactory Sensory Axons to Identifiable Protoglomeruli in the Larval Zebrafish Olfactory Bulb

During development, sensory neurons in the olfactory epithelium extend axons into the olfactory bulb. The earliest axons to enter the bulb terminate onto distinct neuropilar condensations called protoglomeruli. Protoglomeruli are thought to segregate into individual glomeruli later in development. The three day old larval zebrafish olfactory bulb contains 12 stereotyped, identifiable protoglomeruli, rendering it a good system to investigate mechanisms of initial axonal targeting in the bulb. In this thesis, I describe the generation of transgenic zebrafish lines in which neurons expressing odorant receptors along with the olfactory marker protein (OMP), V2R vomeronasal receptors along with the transient receptor potential channel2 (TRPC2) or the odorant receptor OR111-7 are selectively labeled. OMP and TRPC2 expressing neurons innervate multiple, non-overlapping protoglomeruli. Transgenic neurons expressing OR111-7:IRES:Gal4; UAS:Citrine transgenes primarily target a single protoglomerulus, the central zone, allowing the investigation of mechanisms directing axonal navigation to an individual protoglomerulus. Using this transgenic line, I show for the first time in any system that netrin/DCC signaling is required to guide olfactory sensory axons to a specific location within the olfactory bulb. Interestingly, I find that the central zone protoglomerulus is innervated by neurons expressing related odorant receptors of the OR111 subfamily. Upon replacing the coding sequence of OR111-7 in the OR111-7:IRES:Gal4 transgenic construct with RFP, axons continue to target the central zone, suggesting that the OR111-7 is not required for the protoglomerular targeting of transgene expressing axons. Rather, it is likely that the transgenic construct is selectively expressed in neurons destined to target the central zone. Based on these observations, I propose a model hypothesizing that the zebrafish olfactory epithelium consists of distinct neuronal subsets. Each subset innervates a specific protoglomerulus and is restricted to express a predetermined set of odorant receptors and axon guidance receptors, which mediate the navigation of axons to particular protoglomeruli. These studies have laid the groundwork for future investigations into the mechanisms of axonal targeting to protoglomeruli in the larval zebrafish olfactory bulb

On the Geographic Location of Internet Resources

One relatively unexplored question about the Internet's physical structure concerns the geographical location of its components: routers, links and autonomous systems (ASes). We study this question using two large inventories of Internet routers and links, collected by different methods and about two years apart. We first map each router to its geographical location using two different state-of-the-art tools. We then study the relationship between router location and population density; between geographic distance and link density; and between the size and geographic extent of ASes. Our findings are consistent across the two datasets and both mapping methods. First, as expected, router density per person varies widely over different economic regions; however, in economically homogeneous regions, router density shows a strong superlinear relationship to population density. Second, the probability that two routers are directly connected is strongly dependent on distance; our data is consistent with a model in which a majority (up to 75-95%) of link formation is based on geographical distance (as in the Waxman topology generation method). Finally, we find that ASes show high variability in geographic size, which is correlated with other measures of AS size (degree and number of interfaces). Among small to medium ASes, ASes show wide variability in their geographic dispersal; however, all ASes exceeding a certain threshold in size are maximally dispersed geographically. These findings have many implications for the next generation of topology generators, which we envisage as producing router-level graphs annotated with attributes such as link latencies, AS identifiers and geographical locations.National Science Foundation (CCR-9706685, ANI-9986397, ANI-0095988, CAREER ANI-0093296); DARPA; CAID

Shortest path discovery of complex networks

In this paper we present an analytic study of sampled networks in the case of some important shortest-path sampling models. We present analytic formulas for the probability of edge discovery in the case of an evolving and a static network model. We also show that the number of discovered edges in a finite network scales much slower than predicted by earlier mean field models. Finally, we calculate the degree distribution of sampled networks, and we demonstrate that they are analogous to a destructed network obtained by randomly removing edges from the original network.Comment: 10 pages, 4 figure

Nonlinear saturation of Rayleigh-Taylor instability and generation of shear flow in equatorial spread-F plasma

International audienceAn analysis of low order mode coupling equations is used to describe the nonlinear behaviour of the Rayleigh-Taylor (RT) instability in the equatorial ionosphere. The nonlinear evolution of RT instability leads to the development of shear flow. It is found that there is an interplay between the nonlinearity and the shear flow which compete with each other and saturate the RT mode, both in the collisionless and collisional regime. However, the nonlinearly saturated state, normally known as vortices or bubbles, may not be stable. Under certain condition these bubbles are shown to be unstable to short scale secondary instabilities that are driven by the large gradients which develop within these structures. Some understanding of the role of collisional nonlinearity in the shear flow generations is also discussed

Canonical Interpretation of the D_{sJ}(2860) and D_{sJ}(2690)

The spectrum and decay properties of radially excited $D_s$ states are examined in a new model. Good agreement is obtained with the properties of two recently announced $D_s$ mesons identified as $D_{s0}(2860) = c\bar{s}(2P)$ and $D^*_{s}(2690) = c\bar{s}$ as a possible mixture of $(2S;{}^3S_1)$ and $(1D;{}^3D_1)$. Searching for these mesons in B decays is advocated due to large predicted branching ratios.Comment: 6 pages, 2 ps figures, revte

Analysis of OD Flows (Raw Data)

In a recent paper, Structural Analysis of Network Traffic Flows, we analyzed the set of Origin Destination traffic flows from the Sprint-Europe and Abilene backbone networks. This report presents the complete set of results from analyzing data from both networks. The results in this report are specific to the Sprint-1 and Abilene datasets studied in the above paper. The following results are presented here: 1 Rows of Principal Matrix (V) 2 1.1 Sprint-1 Dataset ................................ 2 1.2 Abilene Dataset.................................. 9 2 Set of Eigenflows 14 2.1 Sprint-1 Dataset.................................. 14 2.2 Abilene Dataset................................... 21 3 Classifying Eigenflows 26 3.1 Sprint-1 Dataset.................................. 26 3.2 Abilene Datase.................................... 44Centre National de la Recherche Scientifique (CNRS) France; Sprint Labs; Office of Naval Research (N000140310043); National Science Foundation (ANI-9986397, CCR-0325701

Anomalous width variation of rarefactive ion acoustic solitary waves in the context of auroral plasmas

The presence of dynamic, large amplitude solitary waves in the auroral regions of space is well known. Since their velocities are of the order of the ion acoustic speed, they may well be considered as being generated from the nonlinear evolution of ion acoustic waves. However, they do not show the expected width-amplitude correlation for K-dV solitons. Recent POLAR observations have actually revealed that the low altitude rarefactive ion acoustic solitary waves are associated with an increase in the width with increasing amplitude. This indicates that a weakly nonlinear theory is not appropriate to describe the solitary structures in the auroral regions. In the present work, a fully nonlinear analysis based on Sagdeev pseudopotential technique has been adopted for both parallel and oblique propagation of rarefactive solitary waves in a two electron temperature multi-ion plasma. The large amplitude solutions have consistently shown an increase in the width with increasing amplitude. The width-amplitude variation profile of obliquely propagating rarefactive solitary waves in a magnetized plasma have been compared with the recent POLAR observations. The width-amplitude variation pattern is found to fit well with the analytical results. It indicates that a fully nonlinear theory of ion acoustic solitary waves may well explain the observed anomalous width variations of large amplitude structures in the auroral region