611 research outputs found
Disseminated Herpes Simplex Type 2 and Systemic Candida Infection in a Patient with Previous Asymptomatic Human Immunodeficiency Virus Infection
Direct Observation and Anisotropy of the Contribution of Gap nodes in the Low Temperature Specific Heat of YBa_2Cu_3O_7
The specific heat due to line nodes in the superconducting gap of YBa2Cu3O7
has been obscured up to now by magnetic terms of extrinsic origin, even for
high quality crystals. We report the specific heat of a new single crystal
grown in a non-corrosive BaZrO3 crucible, for which paramagnetic terms are
reduced to less than one spin-1/2 center for 20'000 Cu atoms. The contribution
of line nodes shows up directly in the difference C(B,T) - C(0,T) at fixed
temperatures (T < 5 K) as a function of the magnetic field parallel to the
c-axis (B<=14 T). These data illustrate the smooth crossover from C propotional
to T^2 at low fields to C propotional to TB^1/2 at high fields, and provide new
values for gap parameters which are quantitatively consistent with tunneling
spectroscopy and thermal conductivity in the framework of dx^2-y^2 pairing
symmetry. Data for B along the nodal and antinodal directions in the ab-plane
are also provided. The in-plane anisotropy predicted in the clean limit is not
observed.Comment: 29 pages(using Revtex style), 14 postscript figures, submitted to
Phys. Rev. B Content of the file changed after replacin
Uncovering strong MgII absorbing galaxies: Imaging below the Lyman limit
The nature of the galaxies that give rise to absorption lines, such as damped
Lyman-alpha systems (DLAs) or strong MgII lines, in quasar spectra is difficult
to investigate in emission. Taking advantage of the total absorption of the QSO
light bluewards of the Lyman limit of two DLAs at z>3.4, we look for the
continuum emission from intervening galaxies at z~2 that are identified via
strong metal absorption lines. The MgII absorbers have equivalent width large
enough to be potential DLA systems. Deep images are obtained with the FOcal
Reducer and Spectrograph (FORS1) on the Very Large Telescope for the fields
towards SDSS J110855+120953 and SDSS J140850+020522. These quasars have MgII
absorption lines at z=1.87 (W_r(MgII)=2.46 A) and z=1.98 (W_r(MgII)=1.89 A),
respectively, and each QSO has two intervening higher redshift DLAs at z>3. The
U and R bands of FORS1 lie blue and redwards of the Lyman limit of the
background DLAs, allowing us to search for emission from the foreground
galaxies directly along the lines of sight to the QSOs. No galaxies are found
close to the sight line of the QSO to a point source limit of U_AB=28.0. In
both fields, the closest objects lie at an impact parameter of 5 arcsec
corresponding to 40 kpc in projection at z=2, and have typical colours of star
forming galaxies at that redshift. However, the currently available data do not
allow us to confirm if the galaxies lie at the same redshifts as the absorption
systems. A more extended structure is visible in the SDSS J14085+020522 field
at an impact parameter of 0.8 arcsec or 7 kpc. If these objects are at z~2
their luminosities are 0.03-0.04 L* in both fields. The star formation rates
estimated from the UV flux are 0.5-0.6 M_sun yr^-1. (Abbreviated).Comment: 10 pages, Accepted for publication in A&
Observation of d-wave scaling relations in the mixed-state specific heat of YBa2Cu3O7
The low temperature specific heat C(B,T) of an YBa2Cu3O7.00 single crystal is
measured from 1.2 to 10 K in magnetic fields up to 14 T. The anisotropic
component Caniso(T,B)=C(T,B//c)-C(T,B//ab) is a pure vortex quantity obtained
directly from experiment. It follows a scaling relation predicted recently for
line nodes characteristic of d-wave vortices. Our experimental field and
temperature range corresponds to a crossover region where the limit
Caniso(T,B)is proportional to T*sqrt(B) does not strictly apply. The variation
of the entropy caused by the magnetic field at low T is thermodynamically
compatible with measurements near Tc.Comment: submitted to Phys. Rev. Lett. PDF file, 18 page
Hardness of porous nanocrystalline Co-Ni electrodeposits
The Hall-Petch relationship can fail when the grain size is below a critical value of tens of nanometres. This occurs particularly for coatings having porous surfaces. In this study, electrodeposited nanostructured Co-Ni coatings from four different nickel electroplating baths having grain sizes in the range of 11-23 nm have been investigated. The finest grain size, approximately 11 nm, was obtained from a coating developed from the nickel sulphate bath. The Co-Ni coatings have a mixed face centred cubic and hexagonal close-packed structures with varying surface morphologies and different porosities. A cluster-pore mixture model has been proposed by considering no contribution from pores to the hardness. As the porosity effect was taken into consideration, the calculated pore-free hardness is in agreement with the ordinary Hall-Petch relationship even when the grain size is reduced to 11 nm for the Co-Ni coatings with 77±2 at% cobalt. The present model was applied to other porous nanocrystalline coatings, and the Hall-Petch relationship was maintained. © 2013 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht. © KIM and Springer
Influence of Annealing on the Optical and Scintillation Properties of CaWO Single Crystals
We investigate the influence of oxygen annealing on the room temperature
optical and scintillation properties of CaWO single crystals that are being
produced for direct Dark Matter search experiments. The applied annealing
procedure reduces the absorption coefficient at the peak position of the
scintillation spectrum ( nm) by a factor of and leads to an
even larger reduction of the scattering coefficient. Furthermore, the annealing
has no significant influence on the \emph{intrinsic} light yield. An additional
absorption occurring at nm suggests the formation of O hole
centers. Light-yield measurements at room temperature where one crystal surface
was mechanically roughened showed an increase of the \emph{measured} light
yield by and an improvement of the energy resolution at 59.5 keV by
for the annealed crystal. We ascribe this result to the reduction of
the absorption coefficient while the surface roughening is needed to compensate
for the also observed reduction of the scattering coefficient after annealing
Velocity-Metallicity Correlation for high-z DLA Galaxies: Evidence for a Mass-Metallicity Relation?
We used our database of VLT-UVES quasar spectra to build up a sample of 70
Damped Lyman-alpha (DLA) or strong sub-DLA systems with total neutral hydrogen
column densities of log N(HI)>20 and redshifts in the range 1.7<z_abs<4.3. For
each of the systems, we measured in an homogeneous manner the metallicities
relative to Solar, [X/H] (with X=Zn, or S or Si), and the velocity widths of
low-ionization line profiles, Delta V. We provide for the first time evidence
for a correlation between DLA metallicity and line profile velocity width,
which is detected at the 6.1sigma significance level. This confirms the trend
previously observed in a much smaller sample by Wolfe & Prochaska (1998). The
best-fit linear relation is [X/H]=1.55(\pm 0.12) log Delta V -4.33(\pm 0.23)
with Delta V expressed in km/s. The slope of the DLA velocity-metallicity
relation is the same within uncertainties between the higher (z_abs>2.43) and
the lower (z_abs<2.43) redshift halves of our sample. However, the two
populations of systems are statistically different. There is a strong redshift
evolution in the sense that the mean metallicity and mean velocity width
increase with decreasing redshift. We argue that the existence of a DLA
velocity-metallicity correlation, over more than a factor of 100 spread in
metallicity, is probably the consequence of an underlying mass-metallicity
relation for the galaxies responsible for DLA absorption lines. Assuming a
simple linear scaling of the galaxy luminosity with the mass of the dark-matter
halo, we find that the slope of the DLA velocity-metallicity relation is
consistent with that of the luminosity-metallicity relation derived for local
galaxies. [...] abridged.Comment: 10 pages, 4 figures, A&A in pres
Update of the Swiss guidelines on post-treatment Lyme disease syndrome.
Lyme borreliosis is caused by Borrelia burgdorferi sensu lato infection, which responds well to antibiotic therapy in the overwhelming majority of cases. However, despite adequate antibiotic treatment some patients report persisting symptoms which are commonly summarised as post-treatment Lyme disease syndrome (PTLDS). In 2005, the Swiss Society of Infectious Diseases published a case definition for PTLDS. We aimed to review the scientific literature with a special emphasis on the last 10 years, questioning whether the definitions from 2005 are still valid in the light of current knowledge. Furthermore, we describe the clinical history of infection with Borrelia burgdorferi sensu lato, the estimated prevalence of PTLDS, the possible pathogenesis of PTLDS, and treatment options with an emphasis on clinical studies. In summary, we were unable to find a scientific reason for modification of the PTLDS definitions published in 2005. Thus, the diagnostic criteria remain unchanged, namely documented clinical and laboratory evidence of previous infection with B. burgdorferi, a completed course of appropriate antibiotic therapy, symptoms including fatigue, arthralgia, myalgia, cognitive dysfunction or radicular pain persisting for >6 months, a plausible timely association between documented B. burgdorferi infection and onset of symptoms (i.e., persistent or recurrent symptoms that began within 6 months of completion of a recommended antibiotic therapy for early or late Lyme borreliosis), and exclusion of other somatic or psychiatric causes of symptoms. The main therapeutic options remain cognitive behavioural therapy and low-impact aerobic exercise programmes. Growing and unequivocal evidence confirms that prolonged or repeated antibiotic therapy for PTLDS is not beneficial, but potentially harmful and therefore contraindicated. The Guidelines of the Swiss Society of Infectious Diseases offer an evidence based, diagnostic and therapeutic framework for physicians caring for patients suffering from presumptive PTLDS in Switzerland
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