Early tumor response to intraarterial or intravenous administration of carboplatin to treat naturally occurring lower urinary tract carcinoma in dogs.

BackgroundSurvival times and tumor responses associated with malignant neoplasia of the lower urinary tract are poor despite the vast array of current treatments. Therefore, the evaluation of alternative treatments, such as intraarterial administration of chemotherapy (IAC) should be considered.ObjectiveTo describe a technique for superselective catheterization for IAC and to evaluate initial tumor response by ultrasonography after both IAC and intravenous administration of chemotherapy (IVC).AnimalsClient-owned dogs with lower urinary tract neoplasia treated with either IVC (n = 15) or IAC (n = 11).MethodsRetrospective study. An arterial approach via the carotid or femoral artery was utilized to obtain superselective access and administer chemotherapy in the IAC cases. Medical record review was performed, data were recorded, and recorded variables were evaluated statistically.ResultsIntraarterial chemotherapy was successfully administered in all cases. There was a significantly greater decrease in longest unidimensional measurement in the IAC group as compared to the IVC group (P = .013). The IAC group was also significantly more likely to have a tumor response as assessed by modified RECIST guidelines (P = .049). Dogs in the IAC group were significantly less likely to develop anemia (P = .001), lethargy (P = .010) and anorexia (P = .024).Conclusion and clinical importanceThis study demonstrated the feasibility and efficacy of performing IAC for lower urinary tract neoplasia. Further investigation is necessary as the follow-up time was short and the impact on long-term outcome and survival was not determined

On the anomalous thermal conductivity of one-dimensional lattices

The divergence of the thermal conductivity in the thermodynamic limit is thoroughly investigated. The divergence law is consistently determined with two different numerical approaches based on equilibrium and non-equilibrium simulations. A possible explanation in the framework of linear-response theory is also presented, which traces back the physical origin of this anomaly to the slow diffusion of the energy of long-wavelength Fourier modes. Finally, the results of dynamical simulations are compared with the predictions of mode-coupling theory.Comment: 5 pages, 3 figures, to appear in Europhysics Letter

Screening of classical Casimir forces by electrolytes in semi-infinite geometries

We study the electrostatic Casimir effect and related phenomena in equilibrium statistical mechanics of classical (non-quantum) charged fluids. The prototype model consists of two identical dielectric slabs in empty space (the pure Casimir effect) or in the presence of an electrolyte between the slabs. In the latter case, it is generally believed that the long-ranged Casimir force due to thermal fluctuations in the slabs is screened by the electrolyte into some residual short-ranged force. The screening mechanism is based on a "separation hypothesis": thermal fluctuations of the electrostatic field in the slabs can be treated separately from the pure image effects of the "inert" slabs on the electrolyte particles. In this paper, by using a phenomenological approach under certain conditions, the separation hypothesis is shown to be valid. The phenomenology is tested on a microscopic model in which the conducting slabs and the electrolyte are modelled by the symmetric Coulomb gases of point-like charges with different particle fugacities. The model is solved in the high-temperature Debye-H\"uckel limit (in two and three dimensions) and at the free fermion point of the Thirring representation of the two-dimensional Coulomb gas. The Debye-H\"uckel theory of a Coulomb gas between dielectric walls is also solved.Comment: 25 pages, 2 figure

Nanoscale Smoothing and the Analysis of Interfacial Charge and Dipolar Densities

The interface properties of interest in multilayers include interfacial charge densities, dipole densities, band offsets, and screening-lengths, among others. Most such properties are inaccesible to direct measurements, but are key to understanding the physics of the multilayers. They are contained within first-principles electronic structure computations but are buried within the vast amount of quantitative information those computations generate. Thus far, they have been extracted from the numerical data by heuristic nanosmoothing procedures which do not necessarily provide results independent of the smoothing process. In the present paper we develop the theory of nanosmoothing, establishing procedures for both unpolarized and polarized systems which yield interfacial charge and dipole densities and band offsets invariant to the details of the smoothing procedures when the criteria we have established are met. We show also that dipolar charge densities, i. e. the densities of charge transferred across the interface, and screening lengths are not invariant. We illustrate our procedure with a toy model in which real, transversely averaged charge densities are replaced by sums of Gaussians.Comment: 30 pages, 15 figures, 4 table

van der Waals coupling in atomically doped carbon nanotubes

We have investigated atom-nanotube van der Waals (vdW) coupling in atomically doped carbon nanotubes (CNs). Our approach is based on the perturbation theory for degenerated atomic levels, thus accounting for both weak and strong atom-vacuum-field coupling. The vdW energy is described by an integral equation represented in terms of the local photonic density of states (DOS). By solving it numerically, we demonstrate the inapplicability of standard weak-coupling-based vdW interaction models in a close vicinity of the CN surface where the local photonic DOS effectively increases, giving rise to an atom-field coupling enhancement. An inside encapsulation of atoms into the CN has been shown to be energetically more favorable than their outside adsorption by the CN surface. If the atom is fixed outside the CN, the modulus of the vdW energy increases with the CN radius provided that the weak atom-field coupling regime is realized (i.e., far enough from the CN). For inside atomic position, the modulus of the vdW energy decreases with the CN radius, representing a general effect of the effective interaction area reduction with lowering the CN curvature.Comment: 15 pages, 5 figure

The environment of the fast rotating star Achernar - Thermal infrared interferometry with VLTI/MIDI and SIMECA modeling

Context: As is the case of several other Be stars, Achernar is surrounded by an envelope, recently detected by near-IR interferometry. Aims: We search for the signature of circumstellar emission at distances of a few stellar radii from Achernar, in the thermal IR domain. Methods: We obtained interferometric observations on three VLTI baselines in the N band (8-13 mic), using the MIDI instrument. Results: From the measured visibilities, we derive the angular extension and flux contribution of the N band circumstellar emission in the polar direction of Achernar. The interferometrically resolved polar envelope contributes 13.4 +/- 2.5 % of the photospheric flux in the N band, with a full width at half maximum of 9.9 +/- 2.3 mas (~ 6 Rstar). This flux contribution is in good agreement with the photometric IR excess of 10-20% measured by fitting the spectral energy distribution. Due to our limited azimuth coverage, we can only establish an upper limit of 5-10% for the equatorial envelope. We compare the observed properties of the envelope with an existing model of this star computed with the SIMECA code. Conclusions: The observed extended emission in the thermal IR along the polar direction of Achernar is well reproduced by the existing SIMECA model. Already detected at 2.2mic, this polar envelope is most probably an observational signature of the fast wind ejected by the hot polar caps of the star.Comment: A&A Letter, in pres

Spontaneous decay dynamics in atomically doped carbon nanotubes

We report a strictly non-exponential spontaneous decay dynamics of an excited two-level atom placed inside or at different distances outside a carbon nanotube (CN). This is the result of strong non-Markovian memory effects arising from the rapid variation of the photonic density of states with frequency near the CN. The system exhibits vacuum-field Rabi oscillations, a principal signature of strong atom-vacuum-field coupling, when the atom is close enough to the nanotube surface and the atomic transition frequency is in the vicinity of the resonance of the photonic density of states. Caused by decreasing the atom-field coupling strength, the non-exponential decay dynamics gives place to the exponential one if the atom moves away from the CN surface. Thus, atom-field coupling and the character of the spontaneous decay dynamics, respectively, may be controlled by changing the distance between the atom and CN surface by means of a proper preparation of atomically doped CNs. This opens routes for new challenging nanophotonics applications of atomically doped CN systems as various sources of coherent light emitted by dopant atoms.Comment: 10 pages, 4 figure

Cosmic D-Strings and Vortons in Supergravity

Recent developments in string inspired models of inflation suggest that D-strings are formed at the end of inflation. Within the supergravity model of D-strings there are 2(n-1) chiral fermion zero modes for a D-string of winding n. Using the bounds on the relic vorton density, we show that D-strings with winding number n>1 are more strongly constrained than cosmic strings arising in cosmological phase transitions. The D-string tension of such vortons, if they survive until the present, has to satisfy 8\pi G_N \mu \lesssim p 10^{-26} where p is the intercommutation probability. Similarly, D-strings coupled with spectator fermions carry currents and also need to respect the above bound. D-strings with n=1 do not carry currents and evade the bound. We discuss the coupling of D-strings to supersymmetry breaking. When a single U(1) gauge group is present, we show that there is an incompatibility between spontaneous supersymmetry breaking and cosmic D-strings. We propose an alternative mechanism for supersymmetry breaking, which includes an additional U(1), and might alleviate the problem. We conjecture what effect this would have on the fermion zero modes.Comment: 11 page

Expanded Vandermonde powers and sum rules for the two-dimensional one-component plasma

The two-dimensional one-component plasma (2dOCP) is a system of $N$ mobile particles of the same charge $q$ on a surface with a neutralising background. The Boltzmann factor of the 2dOCP at temperature $T$ can be expressed as a Vandermonde determinant to the power $\Gamma=q^{2}/(k_B T)$. Recent advances in the theory of symmetric and anti-symmetric Jack polymonials provide an efficient way to expand this power of the Vandermonde in their monomial basis, allowing the computation of several thermodynamic and structural properties of the 2dOCP for $N$ values up to 14 and $\Gamma$ equal to 4, 6 and 8. In this work, we explore two applications of this formalism to study the moments of the pair correlation function of the 2dOCP on a sphere, and the distribution of radial linear statistics of the 2dOCP in the plane

On a universal photonic tunnelling time

We consider photonic tunnelling through evanescent regions and obtain general analytic expressions for the transit (phase) time $\tau$ (in the opaque barrier limit) in order to study the recently proposed ``universality'' property according to which $\tau$ is given by the reciprocal of the photon frequency. We consider different physical phenomena (corresponding to performed experiments) and show that such a property is only an approximation. In particular we find that the ``correction'' factor is a constant term for total internal reflection and quarter-wave photonic bandgap, while it is frequency-dependent in the case of undersized waveguide and distributed Bragg reflector. The comparison of our predictions with the experimental results shows quite a good agreement with observations and reveals the range of applicability of the approximated ``universality'' property.Comment: RevTeX, 8 pages, 4 figures, 1 table; subsection added with a new experiment analyzed, some other minor change