802 research outputs found
Spectroscopic Constraints on the Surface Magnetic Field of the Accreting Neutron Star EXO 0748-676
Gravitationally redshifted absorption lines of Fe XXVI, Fe XXV, and O VIII
were inferred recently in the X-ray spectrum of the bursting neutron star EXO
0748-676. We place an upper limit on the stellar magnetic field based on the
iron lines. The oxygen absorption feature shows a multiple component profile
that is consistent with Zeeman splitting in a magnetic field of ~(1-2)x10^9
gauss, and for which the corresponding Zeeman components of the iron lines are
expected to be blended together. In other systems, a field strength >5x10^{10}
gauss could induce a blueshift of the line centroids that would counteract
gravitational redshift and complicate the derivation of constraints on the
equation of state of the neutron star.Comment: 5 pages, submitted to Phys. Rev. Let
Magnetic field-induced quantum critical point in YbPtIn and YbPtIn single crystals
Detailed anisotropic (Hab and Hc) resistivity and
specific heat measurements were performed on online-grown YbPtIn and
solution-grown YbPtIn single crystals for temperatures down to 0.4 K,
and fields up to 140 kG; Hab Hall resistivity was also measured on
the YbPtIn system for the same temperature and field ranges. All these
measurements indicate that the small change in stoichiometry between the two
compounds drastically affects their ordering temperatures (T
K in YbPtIn, and K in YbPtIn). Furthermore, a field-induced
quantum critical point is apparent in each of these heavy fermion systems, with
the corresponding critical field values of YbPtIn (H around
35-45 kG and H kG) also reduced compared to the analogous
values for YbPtIn (H kG and H kG
Magneto-optical Kerr effect in
We have measured the magneto-optical Kerr rotation of ferromagnetic
with x=0.2 and 0.4, as well as of serving as
the non-magnetic reference material. As previously for , we could
identify a feature at 1 in the Kerr response which is related with
electronic transitions involving the localized 4f electron states. The absence
of this feature in the data for confirms the relevance of the
partially occupied 4f states in shaping the magneto-optical features of
-based hexaborides. Disorder by -doping broadens the itinerant charge
carrier contribution to the magneto-optical spectra
CeRuSn: a strongly correlated material with nontrivial topology
Topological insulators form a novel state of matter that provides new
opportunities to create unique quantum phenomena. While the materials used so
far are based on semiconductors, recent theoretical studies predict that also
strongly correlated systems can show non-trivial topological properties,
thereby allowing even the emergence of surface phenomena that are not possible
with topological band insulators. From a practical point of view, it is also
expected that strong correlations will reduce the disturbing impact of defects
or impurities, and at the same increase the Fermi velocities of the topological
surface states. The challenge is now to discover such correlated materials.
Here, using advanced x-ray spectroscopies in combination with band structure
calculations, we infer that CeRuSn is a strongly correlated material
with non-trivial topology.Comment: 10 pages, 6 figures, submitted to Scientific Report
Do NHS GP surgeries employing GPs additionally trained in Integrative or Complementary Medicine have lower antibiotic prescribing rates? Retrospective cross-sectional analysis of national primary care prescribing data in England in 2016
ObjectiveTo determine differences in antibiotic prescription rates between conventional General Practice (GP) surgeries and GP surgeries employing general practitioners (GPs) additionally trained in integrative medicine (IM) or complementary and alternative medicine (CAM) (referred to as IM GPs) working within National Health Service (NHS) England.DesignRetrospective study on antibiotic prescription rates per STAR-PU (Specific Therapeutic group Age–sex weighting Related Prescribing Unit) using NHS Digital data over 2016. Publicly available data were used on prevalence of relevant comorbidities, demographics of patient populations and deprivation scores.SettingPrimary Care.Participants7283 NHS GP surgeries in England.Primary outcome measureThe association between IM GPs and antibiotic prescribing rates per STAR-PU with the number of antibiotic prescriptions (total, and for respiratory tract infection (RTI) and urinary tract infection (UTI) separately) as outcome.ResultsIM GP surgeries (n=9) were comparable to conventional GP surgeries in terms of list sizes, demographics, deprivation scores and comorbidity prevalence. Negative binomial regression models showed that statistically significant fewer total antibiotics (relative risk (RR) 0.78, 95% CI 0.64 to 0.97) and RTI antibiotics (RR 0.74, 95% CI 0.59 to 0.94) were prescribed at NHS IM GP surgeries compared with conventional NHS GP surgeries. In contrast, the number of antibiotics prescribed for UTI were similar between both practices.ConclusionNHS England GP surgeries employing GPs additionally trained in IM/CAM have lower antibiotic prescribing rates. Accessibility of IM/CAM within NHS England primary care is limited. Main study limitation is the lack of consultation data. Future research should include the differences in consultation behaviour of patients self-selecting to consult an IM GP or conventional surgery, and its effect on antibiotic prescription. Additional treatment strategies for common primary care infections used by IM GPs should be explored to see if they could be used to assist in the fight against antimicrobial resistance.</jats:sec
Flattening of Single-Particle Spectra in Strongly Correlated Electron Systems and the Violation of the Wiedemann-Franz Law
The renormalization of the Wiedemann-Franz (WF) ratio in strongly correlated
electron systems is analyzed within the Landau quasiparticle picture. We
demonstrate that the WF law is violated: (i) at the quantum critical point,
where the effective mass diverges, and (ii) beyond a point of fermion
condensation, where the single-particle spectrum becomes flat.
Results of the analysis are compared with available experimental data.Comment: 6 pages, 5 figures, added reference
Konsequenzen des großtechnischen Einsatzes der Kernenergie in der Bundesrepublik Deutschland. Teil II: Fragen der Brennstoffentsorgung bei einem großtechnischen Einsatz der Kernenergie in der Bundesrepublik Deutschland
Characterization of anomalous Zeeman patterns in complex atomic spectra
The modeling of complex atomic spectra is a difficult task, due to the huge
number of levels and lines involved. In the presence of a magnetic field, the
computation becomes even more difficult. The anomalous Zeeman pattern is a
superposition of many absorption or emission profiles with different Zeeman
relative strengths, shifts, widths, asymmetries and sharpnesses. We propose a
statistical approach to study the effect of a magnetic field on the broadening
of spectral lines and transition arrays in atomic spectra. In this model, the
sigma and pi profiles are described using the moments of the Zeeman components,
which depend on quantum numbers and Land\'{e} factors. A graphical calculation
of these moments, together with a statistical modeling of Zeeman profiles as
expansions in terms of Hermite polynomials are presented. It is shown that the
procedure is more efficient, in terms of convergence and validity range, than
the Taylor-series expansion in powers of the magnetic field which was suggested
in the past. Finally, a simple approximate method to estimate the contribution
of a magnetic field to the width of transition arrays is proposed. It relies on
our recently published recursive technique for the numbering of LS-terms of an
arbitrary configuration.Comment: submitted to Physical Review
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