DC field induced enhancement and inhibition of spontaneous emission in a cavity

We demonstrate how spontaneous emission in a cavity can be controlled by the application of a dc field. The method is specially suitable for Rydberg atoms. We present a simple argument for the control of emission.Comment: 3-pages, 2figure. accepted in Phys. Rev.

Evaluation of different internal standards for precious metals quantification

The current study involved the evaluation of five different internal standards (Sc, Co, Y, In and La) as well as normal external or direct calibration methods in the simultaneous quantification of all six platinum group metals (PGMs) and gold (precious metals). The use of Sc as internal standard in the quantitative determination of precious metals in a liquid reference material (RM) and the geological Pyroxenite CRM was shown to yield excellent recoveries (> 99%) compared to the other metals used as internal standard in this study and the direct calibration method (> 91 %).Os recovered only 89% of the expected metal content. The evaluation of different proposed models (wavelength combinations, ionization and/or excitation energy) did not succeed in identifying or discriminating between the unsuccessful and successful internal standards. The robustness of the Sc internal standard addition method was evaluated with the variation in solution matrix (addition of HCl and NaCl). The analytical method (total metal recovery) proved to be very sensitive to elevated unmatched HCl matrix levels (above 1.0 mL of HCl (32% v/v) added) and Na+ addition larger than 4 ppm sodium using ICP-OES. KEY WORDS: Internal standard, Scandium, Precious metals, Spectrometric techniques, ICP-OES Bull. Chem. Soc. Ethiop. 2016, 30(1), 55-70.DOI: http://dx.doi.org/10.4314/bcse.v30i1.

Carbon­yl(N-nitroso-N-oxido-1-naphtylamine-κ2 O,O′)(triphenyl­phosphine-κP)rhodium(I) acetone solvate

The title compound, [Rh(C10H7N2O2)(C18H15P)(CO)]·(CH3)2CO, is the second structural report of a metal complex formed with the O,O′-C10H7N2O2 (neocupferrate) ligand. In the crystal structure, the metal centre is surrounded by one carbonyl ligand, one triphenyl­phosphine ligand and the bidentate neocupferrate ligand, forming a distorted square-planar RhCO2P coordination set which is best illustrated by the small O—Rh—O bite angle of 77.74 (10)°. There are no classical hydrogen-bond inter­actions observed for this complex

Magnetic field induced lattice anomaly inside the superconducting state of CeCoIn5_5: evidence of the proposed Fulde-Ferrell-Larkin-Ovchinnikov state

We report high magnetic field linear magnetostriction experiments on CeCoIn$_5$ single crystals. Two features are remarkable: (i) a sharp discontinuity in all the crystallographic axes associated with the upper superconducting critical field $B_{c2}$ that becomes less pronounced as the temperature increases; (ii) a distinctive second order-like feature observed only along the c-axis in the high field (10 T $\lesssim B \leq B_{c2}$) low temperature ($T \lesssim$ 0.35 K) region. This second order transition is observed only when the magnetic field lies within 20$^o$ of the ab-planes and there is no signature of it above $B_{c2}$, which raises questions regarding its interpretation as a field induced magnetically ordered phase. Good agreement with previous results suggests that this anomaly is related to the transition to the Fulde-Ferrel-Larkin-Ovchinnikov superconducting state.Comment: 3 figures, 5 page

Diffuse Galactic Soft Gamma-Ray Emission

The Galactic diffuse soft gamma-ray (30-800 keV) emission has been measured from the Galactic Center by the HIREGS balloon-borne germanium spectrometer to determine the spectral characteristics and origin of the emission. The resulting Galactic diffuse continuum is found to agree well with a single power-law (plus positronium) over the entire energy range, consistent with RXTE and COMPTEL/CGRO observations at lower and higher energies, respectively. We find no evidence of spectral steepening below 200 keV, as has been reported in previous observations. The spatial distribution along the Galactic ridge is found to be nearly flat, with upper limits set on the longitudinal gradient, and with no evidence of an edge in the observed region. The soft gamma-ray diffuse spectrum is well modeled by inverse Compton scattering of interstellar radiation off of cosmic-ray electrons, minimizing the need to invoke inefficient nonthermal bremsstrahlung emission. The resulting power requirement is well within that provided by Galactic supernovae. We speculate that the measured spectrum provides the first direct constraints on the cosmic-ray electron spectrum below 300 MeV.Comment: 26 pages, 7 figure, submitted to Ap

Some Remarks on the Question of Charge Densities in Stationary-Current-Carrying Conductors

Recently, some discussions arose as to the definition of charge and the value of the density of charge in stationary-current-carrying conductors. We stress that the problem of charge definition comes from a misunderstanding of the usual definition. We provide some theoretical elements which suggest that positive and negative charge densities are equal in the frame of the positive ions.Comment: 14 pages, TeX, macro newsym.tex include

Pressure Evolution of a Field Induced Fermi Surface Reconstruction and of the Neel Critical Field in CeIn3

We report high-pressure skin depth measurements on the heavy fermion material CeIn3 in magnetic fields up to 64 T using a self-resonant tank circuit based on a tunnel diode oscillator. At ambient pressure, an anomaly in the skin depth is seen at 45 T. The field where this anomaly occurs decreases with applied pressure until approximately 1.0 GPa, where it begins to increase before merging with the antiferromagnetic phase boundary. Possible origins for this transport anomaly are explored in terms of a Fermi surface reconstruction. The critical magnetic field at which the Neel ordered phase is suppressed is also mapped as a function of pressure and extrapolates to the previous ambient pressure measurements at high magnetic fields and high pressure measurements at zero magnetic field.Comment: 15 pages, 5 figure

Interrelations Between the Neutron's Magnetic Interactions and the Magnetic Aharonov-Bohm Effect

It is proved that the phase shift of a polarized neutron interacting with a spatially uniform time-dependent magnetic field, demonstrates the same physical principles as the magnetic Aharonov-Bohm effect. The crucial role of inert objects is explained, thereby proving the quantum mechanical nature of the effect. It is also proved that the nonsimply connectedness of the field-free region is not a profound property of the system and that it cannot be regarded as a sufficient condition for a nonzero phase shift.Comment: 18 pages, 1 postscript figure, Late

Predator-Induced Vertical Behavior of a Ctenophore

Although many studies have focused on Mnemiopsis leidyi predation, little is known about the role of this ctenophore as prey when abundant in native and invaded pelagic systems. We examined the response of the ctenophore M. leidyi to the predatory ctenophore Beroe ovata in an experiment in which the two species could potentially sense each other while being physically separated. On average, M. leidyi responded to the predator’s presence by increasing variability in swimming speeds and by lowering their vertical distribution. Such behavior may help explain field records of vertical migration, as well as stratified and near-bottom distributions of M. leidyi

Resonance between Noise and Delay

We propose here a stochastic binary element whose transition rate depends on its state at a fixed interval in the past. With this delayed stochastic transition this is one of the simplest dynamical models under the influence of ``noise'' and ``delay''. We demonstrate numerically and analytically that we can observe resonant phenomena between the oscillatory behavior due to noise and that due to delay.Comment: 4 pages, 5 figures, submitted to Phys.Rev.Lett Expanded and Added Reference