Thermal Excitation of Fourth Sound in Liquid Helium II

In narrow channels filled with helium II two wave modes propagate, fourth sound1–3 and the fifth wave mode.4–6 According to new results of theoretical studies,7–8 it has been predicted that it should be possible to excite both wave modes mechanically by vibrating the diaphragm of a condenser microphone as well as thermally by periodically heating the surface of a solid body (e.g., a resistance layer). Shapiro and Rudnick3 have produced and detected fourth-sound signals mechanically. In the present contribution it will be experimentally verified that it is also possible to excite fourth sound thermally. Since the theory7,8 gives the result that fourth sound can be generated thermally only if…

Evidence for a two-phonon octupole vibrational state in208Pb

Collective properties of206,208Pb have been investigated with gamma-ray spectroscopy using nuclear and electromagnetic excitation by208Pb projectiles. From the measurement of particle-particle-γ and particle-particle-γ γ coincidences a new energy level in208Pb at 5.683 MeV was observed and the data suggest an interpretation as a 2-phonon octupole vibrational state with spin 4+ or 6+. For this state one finds the same dynamical deformation parameterβ3 as for the first-excited collective 3− state. The results are compared to predictions of models which consider, in particular, the aspects of the quadrupole interaction and the interaction of the 2-particle pairing vibration with the 2-phonon o…

Analysis of T-2 toxin by HPLC and GC in samples of corn and oats

HPLC is the only physico-chemical method for the analysis of trichothecenes for which no derivatization is necessary. Hence a combination of different methods can be performed. For exclusion of any faulty interpretation of data and in order to decrease the detection limit HPLC should be followed by GC.

Energy Dependence of Collective Flow of Neutrons and Charged Particles in 197AU + 197AU Collisions

Collective flow of nuclear matter is one important aspect of the research performed at heavy ion accelerator laboratories. The phenomenon was predicted on the basis of hydrodynamical calculations [1], and experimental evidence was first presented for the systems 93 Nb + 93 Nb and 197 Au + 197 Au in the projectile energy range between 150 and 1050 MeV/u [2]. The comparison to microscopic calculations shows that nuclear matter is compressed to about two to three times the ground state density and that a substantial fraction of the kinetic energy in the entrance channel is converted into compressional energy [3]. In these calculations, the relation between density and compressional energy depe…

Structural Variability of 3C 111 on Parsec Scales

We discuss the parsec-scale structural variability of the extragalactic jet 3C111 related to a major radio flux density outburst in 2007. The data analyzed were taken within the scope of the MOJAVE, UMRAO, and F-GAMMA programs, which monitor a large sample of the radio brightest compact extragalactic jets with the VLBA, the University of Michigan 26 m, the Effelsberg 100 m, and the IRAM 30m radio telescopes. The analysis of the VLBA data is performed by fitting Gaussian model components in the visibility domain. We associate the ejection of bright features in the radio jet with a major flux-density outburst in 2007. The evolution of these features suggests the formation of a leading compone…

Heat transport of helium II in restricted geometries

The linear heat transport of helium II contained in porous powder samples with mean pore diameters of 1.25µm, 0.17µm and 0.02µm was systematically studied in the temperature range between 0.8 K and 2 K. The effective thermal conductivity was determined by steady-state heat flow measurements and the effective thermal diffusivity by transitory temperature measurements. The experimental results are interpreted by a simple theoretical model. In the framework of this model the linear heat transport consists of two contributions: the laminar flow of the normal fluid (T≳1.4 K) and a diffusion mechanism (T≲1.4 K). At low temperatures (T≲1.2 K) the mean free paths of the elementary excitations of he…

Energy dependence of collective flow of neutrons and protons in197Au+197Au collisions

We investigate the beam energy dependence of neutron and proton squeeze-out in collisions of197Au+197Au atE/A=400—800 MeV. The azimuthal anisotropy that describes the enhanced emission of mid-rapidity neutrons perpendicular to the reaction plane rises strongly with the transverse momentum of the neutrons. This dependence of the azimuthal anisotropy follows a universal curve — independent of beam energy — if the neutron momenta are measured in fractions of the projectile momentum per mass unit. Analogously, the kinetic energy spectra of mid-rapidity neutrons exhibit a universal behaviour as a function of the kinetic energy of the projectile.

Risk for non-AIDS-defining and AIDS-defining cancer of early versus delayed initiation of antiretroviral therapy

BACKGROUND: Immediate initiation of antiretroviral therapy (ART) regardless of CD4 cell count reduces risk for AIDS and non-AIDS-related events in asymptomatic, HIV-positive persons and is the standard of care. However, most HIV-positive persons initiate ART when their CD4 count decreases below 500 × 10 9 cells/L. Consequences of delayed ART on risk for non-AIDS-defining and AIDS-defining cancer, one of the most common reasons for death in HIV, are unclear. OBJECTIVE: To estimate the long-term risk difference for cancer with the immediate ART strategy.DESIGN: Multinational prospective cohort study.SETTING: The D:A:D (Data collection on Adverse events of anti-HIV Drugs) study, which included…

Nonequilibrium magnetization dynamics of gadolinium studied by magnetic linear dichroism in time-resolved 4f core-level photoemission.

The magnetic linear dichroism of the gadolinium 4f core level is studied in a time-resolved photoemission experiment employing laser pump- and synchrotron-radiation probe pulses. Upon optical excitation of the 5d6s valence electrons with femtosecond laser pulses, the magnetic order in the 4f spin system is reduced. Remarkably, the linear dichroism remains at 80% of the equilibrium contrast while the lattice temperature reaches the Curie temperature due to electron-phonon scattering. Contrasting itinerant ferromagnets, this shows that equilibration between the lattice and spin subsystems takes in Gd about 80 ps and is established in parallel with heat diffusion.

Response of BGO detectors to photons of 3–50 MeV energy

Abstract The response of an array of 7 hexagonal BGO detectors each 7.5 cm long (6.7 radiation lengths) with 3.6 cm side-to-side distance was measured using monochromatic photons from the tagged-photon facility at the electron accelerator MAMI A at Mainz. The experimental spectra of the deposited energy for a single detector and for the array of seven modules compare very well with the predictions of Monte Carlo shower simulations using the code GEANT3. Significant improvement of the energy resolution is observed for the summed energy spectra compared to the resolution of a single module. This improvement deteriorates at higher photon energies because the length of the detector is not suffi…

F-GAMMA: On the phenomenological classification of continuum radio spectra variability patterns of Fermi blazars

The F-GAMMA program is a coordinated effort to investigate the physics of Active Galactic Nuclei (AGNs) via multi-frequency monitoring of Fermi blazars. In the current study we show and discuss the evolution of broad-band radio spectra, which are measured at ten frequencies between 2.64 and 142 GHz using the Effelsberg 100-m and the IRAM 30-m telescopes. It is shown that any of the 78 sources studied can be classified in terms of their variability characteristics in merely 5 types of variability. It is argued that these can be attributed to only two classes of variability mechanisms. The first four types are dominated by spectral evolution and can be described by a simple two-component syst…

On the Gerasimov-Drell-Hearn sum rule for the deuteron

The Gerasimov-Drell-Hearn sum rule is evaluated for the deuteron by explicit integration up to a photon energy of 550 MeV including contributions from the photodisintegration channel and from coherent and incoherent single pion production as well. The photodisintegration channel converges fast enough in this energy range and gives a large negative contribution, essentially from the $^1S_0$ resonant state near threshold. Its absolute value is about the same size than the sum of proton and neutron GDH values. It is only partially cancelled by the single pion production contribution. But the incoherent channel has not reached convergence at 550 MeV.

Structural variability of 3C 111 on parsec scales

We discuss the parsec-scale structural variability of the extragalactic jet 3C 111 related to a major radio flux density outburst in 2007. The data analyzed were taken within the scope of the MOJAVE, UMRAO, and F-GAMMA programs, which monitor a large sample of the radio brightest compact extragalactic jets with the VLBA, the University of Michigan 26 m, the Effelsberg 100 m, and the IRAM 30 m radio telescopes. The analysis of the VLBA data is performed by fitting Gaussian model components in the visibility domain. We associate the ejection of bright features in the radio jet with a major flux-density outburst in 2007. The evolution of these features suggests the formation of a leading compo…

A large area detector for high-energy neutrons

Abstract We present design studies, results of test measurements, and Monte Carlo simulations which served as a basis for the realization of a large area neutron detector (LAND). It has a front area of 2m×2m and a depth of 1 m, and features a multilayer structure of passive converter and active scintillator material. The detector is subdivided in independently operating paddles which allow time-of-flight and position measurement. An energy resolution of ΔT n / T n =5.3% for a flight path of 15 m and an overall detection efficiency of ϵ ≈ 1 is anticipated for neutrons with T n ≈ 1 GeV. The operation of LAND at the SIS facility of GSI is described.

The energy calibration of LEP in the 1993 scan

This report summarizes the procedure for providing the absolute energy calibration of the LEP beams during the energy scan in 1993. The average beam energy around the LEP ring was measured in 25 calibrations with the resonant depolarization technique. The time variation of this average beam energy is well described by a model of the accelerator based on monitored quantities. The absolute calibration of the centre of mass energies of the off-peak points is determined with a precision of 2 parts in 10(5) resulting in a systematic error on the Z-mass of about 1.4 MeV and on the Z-width of about 1.5 MeV.

Feasibility of In-Trap Conversion Electron Spectroscopy

We have used REXTRAP at ISOLDE to test the feasibility of in-trap electron spectroscopy. The results of calculations, experiments with various electron sources as well as a first test with trapped radioactive ions are presented.

On the phenomenological classification of continuum radio spectra variability patterns of Fermi blazars

The F-GAMMA program is a coordinated effort to investigate the physics of Active Galactic Nuclei (AGNs) via multi-frequency monitoring of {\em Fermi} blazars. The current study is concerned with the broad-band radio spectra composed of measurement at ten frequencies between 2.64 and 142 GHz. It is shown that any of the 78 sources studied can be classified in terms of their variability characteristics in merely 5 types of variability. The first four types are dominated by spectral evolution and can be reproduced by a simple two-component system made of the quiescent spectrum of a large scale jet populated with a flaring event evolving according to Marscher & Gear (1985). The last type is…

Search forBs0→μ+μ−andB0→μ+μ−Decays with CDF II

A search has been performed for B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -} and B{sup 0} {yields} {mu}{sup +}{mu}{sup -} decays using 7 fb{sup -1} of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. The observed number of B{sup 0} candidates is consistent with background-only expectations and yields an upper limit on the branching fraction of {Beta}(B{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 6.0 x 10{sup -9} at 95% confidence level. We observe an excess of B{sub s}{sup 0} candidates. The probability that the background processes alone could produce such an excess or larger is 0.27%. The probability that the combination of background and the expe…

Measurement of thett¯production cross section inpp¯collisions ats=1.96  TeVusing soft electronb-tagging

The authors present a measurement of the t{bar t} production cross section using events with one charged lepton and jets from p{bar p} collisions at a center-of-mass energy of 1.96 TeV. A b-tagging algorithm based on the probability of displaced tracks coming from the event interaction vertex is applied to identify b quarks from top decay. Using 318 pb{sup -1} of data collected with the CDF II detector, they measure the t{bar t} production cross section in events with at least one restrictive (tight) b-tagged jet and obtain 8.9{sub -1.0}{sup +1.0}(stat.){sub -1.0}{sup +1.1}(syst.) pb. The cross section value assumes a top quark mass of m{sub t} is presented in the paper. This result is cons…

Optical interface created by laser-cooled atoms trapped in the evanescent field surrounding an optical nanofiber.

Trapping and optically interfacing laser-cooled neutral atoms is an essential requirement for their use in advanced quantum technologies. Here we simultaneously realize both of these tasks with cesium atoms interacting with a multi-color evanescent field surrounding an optical nanofiber. The atoms are localized in a one-dimensional optical lattice about 200 nm above the nanofiber surface and can be efficiently interrogated with a resonant light field sent through the nanofiber. Our technique opens the route towards the direct integration of laser-cooled atomic ensembles within fiber networks, an important prerequisite for large scale quantum communication schemes. Moreover, it is ideally su…

Unification and physical interpretation of the radio spectra variability patterns in Fermi blazars and jet emission from NLSy1s

The F-GAMMA program is among the most comprehensive programs that aim at understanding the physics in active galactic nuclei through the multi-frequency monitoring of Fermi blazars. Here we discuss monthly sampled broad-band radio spectra (2.6 - 142 GHz). Two different studies are presented. (a) We discuss that the variability patterns traced can be classified into two classes: (1) to those showing intense spectral-evolution and (2) those showing a self-similar quasi-achromatic behaviour. We show that a simple two-component model can very well reproduce the observed phenomenologies. (b) We present the cm-to-mm behaviour of three gamma-ray bright Narrow Line Seyfert 1 galaxies over time span…

Identification of acetyl-T-2 toxin, a trichothecene, in moldy rice by HPLC and FDMS

Meta-analysis of 74,046 individuals identifies 11 new susceptibility loci for Alzheimer's disease

Eleven susceptibility loci for late-onset Alzheimer&apos;s disease (LOAD) were identified by previous studies; however, a large portion of the genetic risk for this disease remains unexplained. We conducted a large, two-stage meta-analysis of genome-wide association studies (GWAS) in individuals of European ancestry. In stage 1, we used genotyped and imputed data (7,055,881 SNPs) to perform meta-analysis on 4 previously published GWAS data sets consisting of 17,008 Alzheimer&apos;s disease cases and 37,154 controls. In stage 2, 11,632 SNPs were genotyped and tested for association in an independent set of 8,572 Alzheimer&apos;s disease cases and 11,312 controls. In addition to the APOE locu…