Effects of Disorder in a Dilute Bose Gas

We discuss the effects of a weak random external potential on the properties of the dilute Bose gas at zero temperature. The results recently obtained by Huang and Meng for the depletion of the condensate and of the superfluid density are recovered. Results for the shift of the velocity of sound as well as for its damping due to collisions with the external field are presented. The damping of phonons is calculated also for dense superfluids. (submitted to Phys.Rev.B)Comment: 21 pages, Plain Tex, 2 figures available upon request, preprint UTF 31

ELVIS - ELectromagnetic Vector Information Sensor

The ELVIS instrument was recently proposed by the authors for the Indian Chandrayaan-1 mission to the Moon and is presently under consideration by the Indian Space Research Organisation (ISRO). The scientific objective of ELVIS is to explore the electromagnetic environment of the moon. ELVIS samples the full three-dimensional (3D) electric field vector, E(x,t), up to 18 MHz, with selective Nyqvist frequency bandwidths down to 5 kHz, and one component of the magnetic field vector, B(x,t), from a few Hz up to 100 kHz.As a transient detector, ELVIS is capable of detecting pulses with a minimum pulse width of 5 ns. The instrument comprises three orthogonal electric dipole antennas, one magnetic search coil antenna and a four-channel digital sampling system, utilising flexible digital down conversion and filtering together with state-of-the-art onboard digital signal processing.Comment: 8 pages, 3 figures. Submitted to the DGLR Int. Symposium "To Moon and Beyond", Bremen, Germany, 2005. Companion paper to arXiv:astro-ph/050921

Semi-classical twists for sl(3) and sl(4) boundary r-matrices of Cremmer-Gervais type

We obtain explicit formulas for the semi-classical twists deforming the coalgebraic structure of U(sl(3)) and U(sl(4)). In rank 2 and 3 the corresponding universal R-matrices quantize the boundary r-matrices of Cremmer-Gervais type defining Lie Frobenius structures on the maximal parabolic subalgebras in sl(n)

HD101584: Circumstellar characteristics and evolutionary status

We have performed a study of the characteristics of the circumstellar environment of the binary object HD101584, that provides information on a likely evolutionary scenario. We have obtained and analysed ALMA observations, complemented with observations using APEX, of a large number of molecular lines. An analysis of the spectral energy distribution has also been performed. Emissions from 12 molecular species (not counting isotopologues) have been observed, and most of them mapped with angular resolutions in the range 0.1" to 0.6". Four circumstellar components are identified: i) a central compact source of size 0.15", ii) an expanding equatorial density enhancement (a flattened density distribution in the plane of the orbit) of size 3", iii) a bipolar high-velocity outflow (150 km/s), and iv) an hourglass structure. The outflow is directed almost along the line of sight. There is evidence of a second bipolar outflow. The mass of the circumstellar gas is 0.5[D/1 kpc]^2 Msun, about half of it lies in the equatorial density enhancement. The dust mass is 0.01[D/1 kpc]^2 Msun, and a substantial fraction of this is in the form of large-sized, up to 1 mm, grains. The estimated kinetic age of the outflow is 770[D/1 kpc] yr. The kinetic energy and the scalar momentum of the accelerated gas are estimated to be 7x10^(45)[D/1 kpc]^2 erg and 10^(39)[D/1 kpc]^2 g cm/s, respectively. We provide good evidence that the binary system HD101584 is in a post-common-envelope-evolution phase, that ended before a stellar merger. Isotope ratios combined with stellar mass estimates suggest that the primary star's evolution was terminated already on the first red giant branch (RGB). Most of the energy required to drive the outflowing gas was probably released when material fell towards the companion.Comment: Accepted for publication in A&

Theory and Numerics of Gravitational Waves from Preheating after Inflation

Preheating after inflation involves large, time-dependent field inhomogeneities, which act as a classical source of gravitational radiation. The resulting spectrum might be probed by direct detection experiments if inflation occurs at a low enough energy scale. In this paper, we develop a theory and algorithm to calculate, analytically and numerically, the spectrum of energy density in gravitational waves produced from an inhomogeneous background of stochastic scalar fields in an expanding universe. We derive some generic analytical results for the emission of gravity waves by stochastic media of random fields, which can test the validity/accuracy of numerical calculations. We contrast our method with other numerical methods in the literature, and then we apply it to preheating after chaotic inflation. In this case, we are able to check analytically our numerical results, which differ significantly from previous works. We discuss how the gravity wave spectrum builds up with time and find that the amplitude and the frequency of its peak depend in a relatively simple way on the characteristic spatial scale amplified during preheating. We then estimate the peak frequency and amplitude of the spectrum produced in two models of preheating after hybrid inflation, which for some parameters may be relevant for gravity wave interferometric experiments.Comment: 28 pages, 10 figures, refs added, published versio

Relation Between the Widom line and the Strong-Fragile Dynamic Crossover in Systems with a Liquid-Liquid Phase Transition

We investigate, for two water models displaying a liquid-liquid critical point, the relation between changes in dynamic and thermodynamic anomalies arising from the presence of the liquid-liquid critical point. We find a correlation between the dynamic fragility transition and the locus of specific heat maxima $C_P^{\rm max}$ (``Widom line'') emanating from the critical point. Our findings are consistent with a possible relation between the previously hypothesized liquid-liquid phase transition and the transition in the dynamics recently observed in neutron scattering experiments on confined water. More generally, we argue that this connection between $C_P^{\rm max}$ and dynamic crossover is not limited to the case of water, a hydrogen bond network forming liquid, but is a more general feature of crossing the Widom line. Specifically, we also study the Jagla potential, a spherically-symmetric two-scale potential known to possess a liquid-liquid critical point, in which the competition between two liquid structures is generated by repulsive and attractive ramp interactions.Comment: 6 pages and 5 figure

Feasibility study for a numerical aerodynamic simulation facility. Volume 1

A Numerical Aerodynamic Simulation Facility (NASF) was designed for the simulation of fluid flow around three-dimensional bodies, both in wind tunnel environments and in free space. The application of numerical simulation to this field of endeavor promised to yield economies in aerodynamic and aircraft body designs. A model for a NASF/FMP (Flow Model Processor) ensemble using a possible approach to meeting NASF goals is presented. The computer hardware and software are presented, along with the entire design and performance analysis and evaluation

All-fibre source of amplitude-squeezed light pulses

An all-fibre source of amplitude squeezed solitons utilizing the self-phase modulation in an asymmetric Sagnac interferometer is experimentally demonstrated. The asymmetry of the interferometer is passively controlled by an integrated fibre coupler, allowing for the optimisation of the noise reduction. We have carefully studied the dependence of the amplitude noise on the asymmetry and the power launched into the Sagnac interferometer. Qualitatively, we find good agreement between the experimental results, a semi-classical theory and earlier numerical calculations [Schmitt etl.al., PRL Vol. 81, p.2446, (1998)]. The stability and flexibility of this all-fibre source makes it particularly well suited to applications in quantum information science

Effect of Prophylactic Ketoconazole and Nystatin on Fungal Flora

The effect of prophylactic antifungal drugs on oropharyngeal and anterior nares fungal colonization was studied in 20 patients receiving nystatin and 19 patients receiving ketoconazole. Surveillance cultures were obtained weekly for a mean of 27.1 ± 4.8 days in the nystatin group and 44.0 ±6.7 days in the ketoconazole group. Initially, 63.2% of nystatin patients and 77.8% of ketoconazole patients had yeasts in their oropharynx. Neither drug eliminated oropharyngeal yeast colonization; by the end of the first four weeks of surveillance, 66.7% of the nystatin group and 63.6% of the ketoconazole group still had yeasts in the oropharynx. However, both drugs caused a reduction in the quantity of yeasts grown on successive cultures. Filamentous fungi were isolated in baseline cultures in 42.1% of the nystatin patients and 33.3% of the ketoconazole patients. Prophylaxis did not appear to alter carriage of filamentous fungi in the upper airways. Pathogenic filamentous fungi were only rarely isolated, and this rate did not increase with prophylaxis. Resistance to polyene antifungals (nystatin, amphotericin B) or to ketoconazole did not occur as a result of prophylaxis. Zusammenfassung : Untersuchung Über die Pilzflora im Oropharynx und im vorderen Nasenraum unter dem Einfluß einer prophylaktischen antimykotischen Behandlung. 20 Patienten erhielten Nystatin und 19 Patienten Ketoconazol. WÖchentliche Kontrollkulturen wurden in der Nystatin-Gruppe Über einen durchschnittlichen Zeitraum von 27,1 ± 4,8 Tagen und in der Ketoconazol-Gruppe Über 44,0 ± 6,7 Tage durchgefÜhrt. Zu Beginn der Untersuchung hatten 63,2% der Nystatin-Patienten und 77,8% der Ketoconazol-Patienten Hefen im Oropharynx. Keines der beiden Antimykotika eliminierte die oropharyngeale Hefebesiedlung. Nach 4wÖchiger Beobachtung wurden Hefen in der Nystatin-Gruppe bei 76,7% und in der Ketoconazol-Gruppe bei 63,6% im Oropharynx festgestellt. Durch beide Antimykotika wurde jedoch eine Verringerung der kulturell nachweisbaren Hefemengen hervorgerufen. Schimmelpilze fanden sich zu Beginn der Untersuchung bei 42,1% der Nystatin-Patienten und bei 33,3% der Ketoconazol-Patienten. Unter der prophylaktischen Behandlung war keine Verringerung des Vorkommens derartiger Pilze in den oberen Luftwegen feststellbar. Pathogene Schimmelpilze wurden nur sehr selten isoliert und das Vorkommen dieser Pilze stieg unter der prophylaktischen Behandlung nicht an. Eine Resistenz gegenÜber Polyen-Antimykotika (Nystatin, Amphotericin B) oder Ketoconazol trat unter der prophylaktischen Behandlung nicht auf.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74832/1/j.1439-0507.1984.tb02016.x.pd

Blackbody-radiation-assisted molecular laser cooling

The translational motion of molecular ions can be effectively cooled sympathetically to temperatures below 100 mK in ion traps through Coulomb interactions with laser-cooled atomic ions. The distribution of internal rovibrational states, however, gets in thermal equilibrium with the typically much higher temperature of the environment within tens of seconds. We consider a concept for rotational cooling of such internally hot, but translationally cold heteronuclear diatomic molecular ions. The scheme relies on a combination of optical pumping from a few specific rotational levels into a ``dark state'' with redistribution of rotational populations mediated by blackbody radiation.Comment: 4 pages, 5 figure