Mobility of flucarbazone in two prairie soils

Non-Peer Reviewe

Periodic orbit effects on conductance peak heights in a chaotic quantum dot

We study the effects of short-time classical dynamics on the distribution of Coulomb blockade peak heights in a chaotic quantum dot. The location of one or both leads relative to the short unstable orbits, as well as relative to the symmetry lines, can have large effects on the moments and on the head and tail of the conductance distribution. We study these effects analytically as a function of the stability exponent of the orbits involved, and also numerically using the stadium billiard as a model. The predicted behavior is robust, depending only on the short-time behavior of the many-body quantum system, and consequently insensitive to moderate-sized perturbations.Comment: 14 pages, including 6 figure

Oral tongue carcinoma among young patients: An analysis of risk factors and survival

Introduction: The incidence of oral tongue squamous cell carcinoma (OTSCC) in younger adults has rapidly increased over the past two decades. While tobacco and alcohol use may be less likely to cause these tumors, it remains controversial whether differences also exist in their prognosis. Our aim is to examine the risk factors for cancer among young (<45 years old) OTSCC patients at our institution, and to compare their recurrence and survival with older patients in a matched cohort. Materials and methods: All OTSCC patients seen at our institution between 2000 and 2015 were reviewed. Patients under 45 who with sufficient treatment information were matched 1:1 on race, T-stage, and N-stage with patients 45 and older. Three-year recurrence and survival were determined in stratified and adjusted Cox regression models. Results: Of 397 OTSCC patients were seen at our institution, 117 (29%) were less than 45 years old. Younger patients were significantly more likely to be female, (50% vs. 39%; p = 0.04) and to abstain from tobacco (51% vs. 39%; p < 0.01). Young patients in the matched cohort were significantly more likely to have a recurrence (HR 3.9 95% CI 1.4–10.5). There was no difference in overall survival. Conclusion: Younger OTSCC patients in a matched cohort were more likely to recur within 3 years, although there was no difference in overall mortality. Differences in risk factors and recurrence between older and younger patients suggest that some cancer among younger patients may be distinct from traditional OTSCC

Distribution of resonances for open quantum maps

We analyze simple models of classical chaotic open systems and of their quantizations (open quantum maps on the torus). Our models are similar to models recently studied in atomic and mesoscopic physics. They provide a numerical confirmation of the fractal Weyl law for the density of quantum resonances of such systems. The exponent in that law is related to the dimension of the classical repeller (or trapped set) of the system. In a simplified model, a rigorous argument gives the full resonance spectrum, which satisfies the fractal Weyl law. For this model, we can also compute a quantity characterizing the fluctuations of conductance through the system, namely the shot noise power: the value we obtain is close to the prediction of random matrix theory.Comment: 60 pages, no figures (numerical results are shown in other references

Spin-Charge Separation in the t−Jt-J Model: Magnetic and Transport Anomalies

A real spin-charge separation scheme is found based on a saddle-point state of the $t-J$ model. In the one-dimensional (1D) case, such a saddle-point reproduces the correct asymptotic correlations at the strong-coupling fixed-point of the model. In the two-dimensional (2D) case, the transverse gauge field confining spinon and holon is shown to be gapped at {\em finite doping} so that a spin-charge deconfinement is obtained for its first time in 2D. The gap in the gauge fluctuation disappears at half-filling limit, where a long-range antiferromagnetic order is recovered at zero temperature and spinons become confined. The most interesting features of spin dynamics and transport are exhibited at finite doping where exotic {\em residual} couplings between spin and charge degrees of freedom lead to systematic anomalies with regard to a Fermi-liquid system. In spin dynamics, a commensurate antiferromagnetic fluctuation with a small, doping-dependent energy scale is found, which is characterized in momentum space by a Gaussian peak at ($\pi/a$, $\pi/a$) with a doping-dependent width ($\propto \sqrt{\delta}$, $\delta$ is the doping concentration). This commensurate magnetic fluctuation contributes a non-Korringa behavior for the NMR spin-lattice relaxation rate. There also exits a characteristic temperature scale below which a pseudogap behavior appears in the spin dynamics. Furthermore, an incommensurate magnetic fluctuation is also obtained at a {\em finite} energy regime. In transport, a strong short-range phase interference leads to an effective holon Lagrangian which can give rise to a series of interesting phenomena including linear-$T$ resistivity and $T^2$ Hall-angle. We discuss the striking similarities of these theoretical features with those found in the high-$T_c$ cuprates and give aComment: 70 pages, RevTex, hard copies of 7 figures available upon request; minor revisions in the text and references have been made; To be published in July 1 issue of Phys. Rev. B52, (1995

Carrier relaxation, pseudogap, and superconducting gap in high-Tc cuprates: A Raman scattering study

We describe results of electronic Raman-scattering experiments in differently doped single crystals of Y-123 and Bi-2212. The comparison of AF insulating and metallic samples suggests that at least the low-energy part of the spectra originates predominantly from excitations of free carriers. We therefore propose an analysis of the data in terms of a memory function approach. Dynamical scattering rates and mass-enhancement factors for the carriers are obtained. In B2g symmetry the Raman data compare well to the results obtained from ordinary and optical transport. For underdoped materials the dc scattering rates in B1g symmetry become temperature independent and considerably larger than in B2g symmetry. This increasing anisotropy is accompanied by a loss of spectral weight in B2g symmetry in the range between the superconducting transition at Tc and a characteristic temperature T* of order room temperature which compares well with the pseudogap temperature found in other experiments. The energy range affected by the pseudogap is doping and temperature independent. The integrated spectral loss is approximately 25% in underdoped samples and becomes much weaker towards higher carrier concentration. In underdoped samples, superconductivity related features in the spectra can be observed only in B2g symmetry. The peak frequencies scale with Tc. We do not find a direct relation between the pseudogap and the superconducting gap.Comment: RevTeX, 21 pages, 24 gif figures. For PostScript with embedded eps figures, see http://www.wmi.badw-muenchen.de/~opel/k2.htm

Detector Description and Performance for the First Coincidence Observations between LIGO and GEO

For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial change

Long Term Cyclic Pamidronate Reduces Bone Growth by Inhibiting Osteoclast Mediated Cartilage-to-Bone Turnover in the Mouse

Bisphosphonates, used to treat diseases exhibiting increased osteoclast activity, reduce longitudinal bone growth through an as yet undefined mechanism. Pamidronate, an aminobisphosphonate, was given weekly to mice at 0, 1.25, or 2.50 mg/kg/wk beginning at 4 weeks of age. At 12 weeks of age, humeral length, growth plate area, regional chondrocyte cell numbers, chondrocyte apoptosis, TRAP stained osteoclast number, and osteoclast function assessed by cathepsin K immunohistochemistry were quantified. Humeral length was decreased in pamidronate treated mice compared to vehicle control mice, and correlated with greater growth plate areas reflecting greater proliferative and hypertrophic chondrocyte cell numbers with fewer hypertrophic cells undergoing apoptosis. Pamidronate treatment increased TRAP stained osteoclast numbers yet decreased cathepsin K indicating that pamidronate repressed osteoclast maturation and function. The data suggest that long term cyclic pamidronate treatment impairs bone growth by inhibition of osteoclast maturation thereby reducing cartilage-to-bone turnover within the growth plate

Counting the Faces of Randomly-Projected Hypercubes and Orthants, with Applications

Abstract. Let A be an n by N real-valued matrix with n &lt; N; we count the number of k-faces fk(AQ) when Q is either the standard N-dimensional hypercube IN or else the positive orthant RN +. To state results simply, consider a proportional-growth asymptotic, where for fixed δ, ρ in (0, 1), we have a sequence of matrices An,Nn and of integers kn with n/Nn → δ, kn/n → ρ as n → ∞. If each matrix An,Nn has its columns in general position, then fk(AIN)/fk(I N) tends to zero or one depending on whether ρ&gt; min(0, 2 − δ−1) or ρ &lt; min(0, 2 − δ−1). Also, if each An,Nn is a random draw from a distribution which is invariant under right multiplication by signed permutations, then fk(ARN +)/fk(RN +) tends almost surely to zero or one depending on whether ρ&gt; min(0, 2 − δ−1) or ρ &lt; min(0, 2 − δ−1). We make a variety of contrasts to related work on projections of the simplex and/or cross-polytope. These geometric face-counting results have implications for signal processing, information theory, inverse problems, and optimization. Indeed, face counting is related to conditions for uniqueness of solutions of underdetermine