765 research outputs found
Interdependence of magnetism and superconductivity in the borocarbide TmNi2B2C
We have discovered a new antiferromagnetic phase in TmNi2B2C by neutron
diffraction. The ordering vector is Q_A = (0.48,0,0) and the phase appears
above a critical in-plane magnetic field of 0.9 T. The field was applied in
order to test the assumption that the zero-field magnetic structure at Q_F =
(0.094,0.094,0) would change into a c-axis ferromagnet if superconductivity
were destroyed. We present theoretical calculations which show that two effects
are important: A suppression of the ferromagnetic component of the RKKY
exchange interaction in the superconducting phase, and a reduction of the
superconducting condensation energy due to the periodic modulation of the
moments at the wave vector Q_A
DIFFERENCES IN JUMPING PERFORMANCE OF CHILDREN FROM DIFFERENT SPORTS
The ability of high rate of force development is crucial in many high power sports. The aim of this study was to examine the possible differences in jumping skills of children participating in sports with different demands of leg strength, in order to investigate if specific training influenced different jump performances. 175 children from four different sports participated. The subjects performed squat jumps; counter movement jumps and drop jumps from 0.2 m and 0.4 m. The study showed that the nature of the sport has influence on the performance of drop jumping ability on children, though natural selection may also have an influence
Reductive Transformations of Anthropogenic Chemicals in Natural and Technical Systems
Reductive transformation reactions of chemical pollutants (e.g., polyhalogenated hydrocarbons, aromatic azo and nitro compounds, chromium(VI) species) in the environment are important both from an ecotoxicological and from an environmental technology point of view. Using well-defined
model reactors as well as more complex 'real world' systems, several groups at EAWAG are trying to unravel compound- and system-specific factors that control the reduction of a variety of anthropogenic chemicals under different conditions in the environment. The examples presented in this
article include the reduction of nitroaromatic compounds under iron- and sulfate-reducing conditions, the reductive dehalogenation of chlorinated ethenes by cob(I)alamin and by a bacterium that uses such compounds as terminal electron acceptors, and the reduction of chromium(VI) by various
reduced iron species. The link between microbial and abiotic (chemical) processes involved in reductive transformations of pollutants is emphasized. The major goal of this article is to illustrate the approaches taken to elucidate the mechanisms and kinetics of environmentally relevant reduction
reactions of pollutants, and to discuss how the results of such studies can be used 1) to gain insight into what is actually happening in the environment, and 2) to develop methods for the treatment of chemical wastes or contaminated sites
Riboflavin-Vancomycin Conjugate Enables Simultaneous Antibiotic Photo-Release and Photodynamic Killing against Resistant Gram-Positive Pathogens
Decades of antibiotic misuse have led to alarming levels of antimicrobial resistance, and the development of alternative diagnostic and therapeutic strategies to delineate and treat infections is a global priority. In particular, the nosocomial, multidrug-resistant "ESKAPE" pathogens such as Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp (VRE) urgently require alternative treatments. Here, we developed light-activated molecules based on the conjugation of the FDA-approved photosensitizer riboflavin to the Gram-positive specific ligand vancomycin to enable targeted antimicrobial photodynamic therapy. The riboflavin-vancomycin conjugate proved to be a potent and versatile antibacterial agent, enabling the rapid, light-mediated, killing of MRSA and VRE with no significant off-target effects. The attachment of riboflavin on vancomycin also led to an increase in antibiotic activity against S. aureus and VRE. Simultaneously, we evidenced for the first time that the flavin subunit undergoes an efficient photoinduced bond cleavage reaction to release vancomycin, thereby acting as a photoremovable protecting group with potential applications in drug delivery
Investigative Pattern Detection Framework for Counterterrorism
Law-enforcement investigations aimed at preventing attacks by violent
extremists have become increasingly important for public safety. The problem is
exacerbated by the massive data volumes that need to be scanned to identify
complex behaviors of extremists and groups. Automated tools are required to
extract information to respond queries from analysts, continually scan new
information, integrate them with past events, and then alert about emerging
threats. We address challenges in investigative pattern detection and develop
an Investigative Pattern Detection Framework for Counterterrorism (INSPECT).
The framework integrates numerous computing tools that include machine learning
techniques to identify behavioral indicators and graph pattern matching
techniques to detect risk profiles/groups. INSPECT also automates multiple
tasks for large-scale mining of detailed forensic biographies, forming
knowledge networks, and querying for behavioral indicators and radicalization
trajectories. INSPECT targets human-in-the-loop mode of investigative search
and has been validated and evaluated using an evolving dataset on domestic
jihadism.Comment: 9 pages, 4 figure
Mermin-Ho vortex in ferromagnetic spinor Bose-Einstein condensates
The Mermin-Ho and Anderson-Toulouse coreless non-singular vortices are
demonstrated to be thermodynamically stable in ferromagnetic spinor
Bose-Einstein condensates with the hyperfine state F=1. The phase diagram is
established in a plane of the rotation drive vs the total magnetization by
comparing the energies for other competing non-axis-symmetric or singular
vortices. Their stability is also checked by evaluating collective modes.Comment: 4 pages, 4 figure
Energies and damping rates of elementary excitations in spin-1 Bose-Einstein condensed gases
Finite temperature Green's function technique is used to calculate the
energies and damping rates of elementary excitations of the homogeneous,
dilute, spin-1 Bose gases below the Bose-Einstein condensation temperature both
in the density and spin channels. For this purpose the self-consistent
dynamical Hartree-Fock model is formulated, which takes into account the direct
and exchange processes on equal footing by summing up certain classes of
Feynman diagrams. The model is shown to fulfil the Goldstone theorem and to
exhibit the hybridization of one-particle and collective excitations correctly.
The results are applied to the gases of ^{23}Na and ^{87}Rb atoms.Comment: 26 pages, 21 figures. Added 2 new figures, detailed discussio
Evaluation of in situ measurements of atmospheric carbon monoxide at Mount Waliguan, China
Quasicontinuous measurements of carbon monoxide (CO) recorded over three years at Mount Waliguan (WLG), a global baseline station in remote western China, were examined using back trajectory analysis. The data include a revision to correct the working reference scale to the WMO2000 scale and corrections for drift in the reference gases. Between July 2004 and June 2007, CO exhibited large fluctuations and the 5 %, 50 % and 95 %-percentiles of relevant CO mixing ratios were 102 ppb, 126 ppb and 194 ppb. Approximately 50 % of all observed data were selected as CO background data using a mathematical procedure of robust local regression, with the remainder affected by regional-scale pollution. The monthly mean background CO mixing ratios showed a minimum in summer and a maximum in late winter, although all seasons were affected by short-term enhancements that exceeded background levels. The CO data were compared to values observed at the high alpine research station at Jungfraujoch, Switzerland. Smaller seasonal amplitudes were observed at WLG compared to the Jungfraujoch due to lower winter and spring CO levels, however, episodic enhancements of polluted air were greater at WLG. The air parcels arriving at WLG came predominately from the west, except in summer when advection from the east and southeast prevailed. Transport from the east or southeast typically brought polluted air to the site, having passed over populated urban areas upwind. A large number of elevated CO mixing ratios could also be associated with advection from the northwest of WLG via the central Xinjiang Uygur Autonomous Region (XUAR) and the Ge'ermu urban area where growing industrial activities as well as crops residue burning provide sources of CO. Air masses passing over northwestern Gansu were associated with relatively high CO values suggesting an anthropogenic influence, which was likely due to anthropogenic emissions from northwestern China (based on back-trajectory and potential source contribution analysis and on the INTEX-B: intercontinental Chemical Transport Experiment-Phase B). Background conditions were observed most frequently in air parcels from remote Tibet west of WLG. The probability that air parcels pass over regions of clean or polluted regions was further identified using potential source contribution function (PSCF) analysis
- …