Point-contact tunneling spectroscopy measurement of Cux_xTiSe2_2: disorder-enhanced Coulomb effects

We performed point-contact spectroscopy tunneling measurements on Cu$_x$TiSe$_2$ bulk with $x=0.02$ and $0.06$ at temperatures ranging from $T=4-40$ K and observe a suppression in the density of states around zero-bias that we attribute to enhanced Coulomb interactions due to disorder. We find that the correlation gap associated with this suppression is related to the zero-temperature resistivity. We use our results to estimate the disorder-free transition temperature and find that the clean limit $T_{c0}$ is close to the experimentally observed $T_c$.Comment: 4 pages, 4 figure

Superconducting niobium thin film slow-wave structures

A superconducting comb structure as a slow-wave element in a traveling-wave maser will significantly improve maser noise temperature and gain by reducing the insertion loss. The results of the insertion loss measurements of superconducting niobium slow-wave structures subjected to maser operating conditions at X-Band frequencies are presented

Anomalous double peak structure in Nb/Ni superconductor/ferromagnet tunneling DOS

We have experimentally investigated the density of states (DOS) in Nb/Ni (S/F) bilayers as a function of Ni thickness, $d_F$. Our thinnest samples show the usual DOS peak at $\pm\Delta_0$, whereas intermediate-thickness samples have an anomalous ``double-peak'' structure. For thicker samples ($d_F \geq 3.5$ nm), we see an ``inverted'' DOS which has previously only been reported in superconductor/weak-ferromagnet structures. We analyze the data using the self-consistent non-linear Usadel equation and find that we are able to quantitatively fit the features at $\pm\Delta_0$ if we include a large amount of spin-orbit scattering in the model. Interestingly, we are unable to reproduce the sub-gap structure through the addition of any parameter(s). Therefore, the observed anomalous sub-gap structure represents new physics beyond that contained in the present Usadel theory.Comment: 4 pages, 3 figure

MECHANICAL MODEL FOR DETERMINING BASE RUNNING SPEED OF SOFTBALL PLAYERS

INTRODUCT10N -Speed on the bases is critical for fast pitch softball players. A mechanical model of critical features contributing to this speed is important for both the coach and athlete for success. The purpose of this study was to develop a model and determine which variables the coach could manipulate to enhance the success of the players. METHODS• Hat (1993) proposed a deterministic model for sprinting. Average speed was determined by stride length (SL) and stride frequency (SF). SL was further divided into takeoff distance, flight distance, and landing distance with mechanical variables which contribute to these distances supporting SL. SF was also further divided into stride time and additional mechanical variables. Our model incorporated these variables and included variables related to the physical characteristics of the subjects which could be manipulated by the athlete coach. Thirty-nine female NAIA and Division 11 softball players served as subjects. RESULTS -A database was created to determine the demographics of the population selected and of the preliminary data for the proposed model. The data in the table 00low represents the demographics of the population. The data were used 10 support our model and develop a practical approach to enhancing speed of a softball player. Hay, J.G. (1993). The Biomechanics of Sport Techniques. New Jersey: PrenliceHall, pp. 396-422 (Track and fjeld: Running)

FACTORS CONTRIBUTING TO SOFTBALL PLAYERS BASE RUNNING SPEED

INTRODUCTION • The fast pitch softball player relies on speed to reach a base successfully. The purpose of this study was to determine the mechanical variables which contribute to the success of the player on the base paths. METHODS -Thirty-nine female NAIA and Division 11 softball players served as subjects. Subjects were tested with a battery attests based on the theoretical model proposed earlier. Subjects were also videotaped in the sagittal view running from home plate to first base. The video images were captured, transformed, smoothed, and graphed with the Arie! Performance Analysis System (APAS). Data were statistically determined with regression analysis to determine which variables would predict speed. RESULTS • The dependent variable was fly 40 time and the independent variables age, wgt, hgt, percent body fat, sit and reach, sit-ups, leg press, stat 40 times, stride length. cog displacement x, trunk inc1ination, and angular displacement at the hip, knee, and ankle. The demographie data were presented previously. The kinematic data are displayed in the table below The variable with the highest regression coefficient to the fly 40 times was leg press (r=.8692). Stat 40 time was highly correlated to fly 40 times (r=.7354). CONCLUSIONS• The kinematic variables selected did not aid in the prediction process. Because of this the model may be revised and/or different variables selected for interpretation

Measurement of the Parallax of PSR B0950+08 Using the VLBA

A new technique has been developed to remove the ionosphere's distorting effects from low frequency VLBI data. By fitting dispersive and non-dispersive components to the phases of multi-frequency data, the ionosphere can be effectively removed from the data without the use of {\em a priori} calibration information. This technique, along with the new gating capability of the VLBA correlator, was used to perform accurate astrometry on pulsar B0950+08, resulting in a much improved measurement of this pulsar's proper motion ($\mu_{\alpha} = -1.6 \pm 0.4$ mas/yr, $\mu_{\delta} = 29.5 \pm 0.5$ mas/yr) and parallax ($\pi = 3.6 \pm 0.3$ mas). This puts the pulsar at a distance of $280 \pm 25$ parsecs, about twice as far as previous estimates, but in good agreement with models of the electron density in the local bubble.Comment: 5 pages, Latex with AASTEX. Accepted for publication in Ap

The Metallicity of Pre-Galactic Globular Clusters: Observational consequences of the first stars

We explore a scenario where metal-poor globular clusters (GCs) are enriched by the first supernovae in the Universe. If the first stars in a 10^7 Msun dark halo were very massive (>180 Msun), then a pair instability supernova from a single massive star can produce sufficient iron to enrich 10^6 Msun of pristine, primordial gas to [Fe/H] ~ -2. In such a scenario, where a single massive star acts as a seed for halo GCs, the accurate abundance analysis of GC stars would allow a direct measurement of the Population III initial mass. Using the latest theoretical yields for zero metallicity stars in the mass range 140-260 Msun, we find that the metals expelled from a ~230 Msun star are consistent with [Si/Fe] and [Ca/Fe] observed in GC stars. However, no single star in this mass range can simultaneously explain all halo GC heavy-element abundance ratios, such as [V/Fe], [Ti/Fe] and [Ni/Fe]. These require a combination masses for the Population III stellar progenitors. The various observational consequences of this scenario are discussed.Comment: 5 pages, 2 figures, accepted for publication in ApJ Lette