1,563 research outputs found
Paramagnon dispersion in -FeSe observed by Fe -edge resonant inelastic x-ray scattering
We report an Fe -edge resonant inelastic x-ray scattering (RIXS) study of
the unusual superconductor -FeSe. The high energy resolution of this
RIXS experiment (55meV FWHM) made it possible to resolve
low-energy excitations of the Fe manifold. These include a broad peak
which shows dispersive trends between 100-200meV along the and
directions of the one-Fe square reciprocal lattice, and which can
be attributed to paramagnon excitations. The multi-band valence state of FeSe
is among the most metallic in which such excitations have been discerned by
soft x-ray RIXS
Absolute conservation law for black holes
In all 2d theories of gravity a conservation law connects the (space-time
dependent) mass aspect function at all times and all radii with an integral of
the matter fields. It depends on an arbitrary constant which may be interpreted
as determining the initial value together with the initial values for the
matter field. We discuss this for spherically reduced Einstein-gravity in a
diagonal metric and in a Bondi-Sachs metric using the first order formulation
of spherically reduced gravity, which allows easy and direct fixations of any
type of gauge. The relation of our conserved quantity to the ADM and Bondi mass
is investigated. Further possible applications (ideal fluid, black holes in
higher dimensions or AdS spacetimes etc.) are straightforward generalizations.Comment: LaTex, 17 pages, final version, to appear in Phys. Rev.
High-resolution resonant inelastic soft X-ray scattering as a probe of the crystal electrical field in lanthanides demonstrated for the case of CeRh2Si2
The magnetic properties of rare earth compounds are usually well captured by
assuming a fully localized f shell and only considering the Hund's rule ground
state multiplet split by a crystal electrical field (CEF). Currently, the
standard technique for probing CEF excitations in lanthanides is inelastic
neutron scattering. Here we show that with the recent leap in energy
resolution, resonant inelastic soft X-ray scattering has become a serious
alternative for looking at CEF excitations with some distinct advantages
compared to INS. As an example we study the CEF scheme in CeRh2Si2, a system
that has been intensely studied for more than two decades now but for which no
consensus has been reached yet as to its CEF scheme. We used two new features
that have only become available very recently in RIXS, high energy resolution
of about 30 meV as well as polarization analysis in the scattered beam, to find
a unique CEF description for CeRh2Si2. The result agrees well with previous INS
and magnetic susceptibility measurements. Due to its strong resonant character,
RIXS is applicable to very small samples, presents very high cross sections for
all lanthanides, and further benefits from the very weak coupling to phonon
excitation. The rapid progress in energy resolution of RIXS spectrometers is
making this technique increasingly attractive for the investigation of the CEF
scheme in lanthanides
A Vector Supersymmetry in Noncommutative U(1) Gauge Theory with the Slavnov Term
We consider noncommutative U(1) gauge theory with the additional term,
involving a scalar field lambda, introduced by Slavnov in order to cure the
infrared problem. we show that this theory, with an appropriate space-like
axial gauge-fixing, wxhibits a linear vector supersymmetry similar to the one
present in the 2-dimensional BF model. This vector supersymmetry implies that
all loop corrections are independent of the -vertex and thereby
explains why Slavnov found a finite model for the same gauge-fixing.Comment: 18 pages, 3 figures; v2 Acknowledgments adde
Des(1–3)IGF-1 Treatment Normalizes Type 1 IGF Receptor and Phospho-Akt (Thr 308) Immunoreactivity in Predegenerative Retina of Diabetic Rats
Little is known about interventions that may prevent predegenerative changes in the diabetic retina. This study tested the hypothesis that immediate, systemic treatment with an insulin-like growth factor (IGF)-1 analog can prevent abnormal accumulations of type 1 IGF receptor, and phospho-Akt (Thr 308) immunoreactivity in predegenerative retinas of streptozotocin (STZ) diabetic rats. Type 1 IGF receptor immunoreactivity increased approximately 3-fold in both inner nuclear layer (INL) and ganglion cell layer (GCL) in retinas from STZ rats versus nondiabetic controls. Phospho-Akt (Thr 308) immunoreactivity increased 5-fold in GCL and 8-fold in INL of STZ rat retinas. In all cases, immunoreactive cells were significantly reduced in STZ des(1–3)IGF-1–treated versus STZ rats. Preliminary results suggested that vascular endothelial growth factor (VEGF) levels may also be reduced. Hyperglycemia/ failure of weight gain in diabetic rats continued despite systemic des(1–3)IGF-1. These data show that an IGF-1 analog can prevent early retinal biochemical abnormalities implicated in the progression of diabetic retinopathy, despite ongoing hyperglycemia
Universal conservation law and modified Noether symmetry in 2d models of gravity with matter
It is well-known that all 2d models of gravity---including theories with
nonvanishing torsion and dilaton theories---can be solved exactly, if matter
interactions are absent. An absolutely (in space and time) conserved quantity
determines the global classification of all (classical) solutions. For the
special case of spherically reduced Einstein gravity it coincides with the mass
in the Schwarzschild solution. The corresponding Noether symmetry has been
derived previously by P. Widerin and one of the authors (W.K.) for a specific
2d model with nonvanishing torsion. In the present paper this is generalized to
all covariant 2d theories, including interactions with matter. The related
Noether-like symmetry differs from the usual one. The parameters for the
symmetry transformation of the geometric part and those of the matterfields are
distinct. The total conservation law (a zero-form current) results from a two
stage argument which also involves a consistency condition expressed by the
conservation of a one-form matter ``current''. The black hole is treated as a
special case.Comment: 3
Enhanced Recovery Pathway for Right and Left Colectomy: Comparison of Functional Recovery.
Enhanced recovery (ERAS) guidelines do not differentiate between left- and right-sided colectomies, but differences in recovery have been reported for the two procedure types. We aimed to compare compliance with the ERAS protocol and outcomes after right versus left colectomy.
Between June 2011 and September 2014, all patients undergoing elective colonic resection were treated according to a standardized ERAS protocol and entered a prospective database. This retrospective analysis compared right and left colectomy regarding application of the ERAS pathway, bowel recovery, complications, and hospital stay.
Eighty-five patients with right colectomy matched well with 138 left-sided resections for baseline demographics. Overall compliance with the ERAS protocol was 76 % for right versus 77 % for left colectomy patients (p = 0.492). First flatus occurred at postoperative day 2 in both groups (p = 0.057); first stool was observed after a median of 3 (right) and 2 days (left), respectively (p = 0.189). Twenty patients (24 %) needed postoperative nasogastric tube after right colectomy compared to 11 patients (8 %) after left colectomy (p = 0.002). Overall complication rates were 49 and 37 % for right and left colectomy, respectively (p = 0.071). Median postoperative length of stay was 6 days (IQR 4-9) after right and 5 days (IQR 4-7.5) after left colectomy (p = 0.020).
Overall compliance with the protocol was equally high in both groups showing that ERAS protocol was applicable for right and left colectomy. Functional recovery however, tended to be slower after right colectomy, and postoperative ileus rate was significantly higher. More cautious early feeding after right colectomy should be considered
Gauge Independence of IR singularities in Non-Commutative QFT - and Interpolating Gauges
IR divergences of a non-commutative U(1) Maxwell theory are discussed at the
one-loop level using an interpolating gauge to show that quadratic IR
divergences are independent not only from a covariant gauge fixing but also
independent from an axial gauge fixing.Comment: 11 pages, 2 figures, v1 minor correction
Monopole Vacuum in Non-Abelian Theories
It is shown that, in the theory of interacting Yang -Mills fields and a Higgs
field, there is a topological degeneracy of Bogomol'nyi-Prasad-Sommerfield
(BPS) monopoles and that there arises, in this case, a chromoelectric monopole
characterized by a new topological variable that describes transitions between
topological states of the monopole in the Minkowski space (in just the same way
as an instanton describes such transitions in the Euclidean space). The limit
of an infinitely large mass of the Higgs field at a finite density of the BPS
monopole is considered as a model of the stable vacuum in the pure Yang-Mills
theory. It is shown that, in QCD, such a monopole vacuum may lead to a rising
potential, a topological confinement and an additional mass of the
meson. The relationship between the result obtained here for the generating
functional of perturbation theory and Faddeev-Popov integral is discussed
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