47 research outputs found
Comparison of the reliability of snap foal Ig test, Gamma-Check E test, refractometry and electrophoresis for determining the immune status of newborn foals in the first hours of life
Twenty-eight warmblood mares were monitored during their late pregnancy in the Teaching Hospital of Ghent University. The reliability of two commercial assays (enzyme immunoassay and glutaraldehyde coagulation test) used for determining the IgG concentrations of their newborn foals was tested. Mammary secretions were examined at the time of foaling (T0), and then 4 (T1) and 8 (T2) hours after foaling by refractometry and electrophoresis. The foalsâ blood IgG levels were measured at T1 and T2 as a routine clinical diagnostic examination using two different commercial test kits (SNAP Foal Ig and Gamma-Check E) and T0, T1 and T2 samples were stored (at â18 °C) for immunoglobulin (Ig) determination by electrophoresis. Differences between the results of refractometry and electrophoresis occurred in 27.8% of the colostrum analyses. Some serum IgG could be detected immediately post partum (T0) in 75% of the foals, and 42.82% of the newborn foals acquired a serum concentration of more than 800 mg/dl IgG within 8 h of birth. Compared to the electrophoresis, the glutaraldehyde test scored better (85%) than the enzyme immunoassay (74%), although both are accurate and safe to use since they clearly distinguish between safe and unsafe IgG concentrations
Experimental Determination of Momentum-Resolved Electron-Phonon Coupling
We provide a novel experimental method to quantitatively estimate the
electron-phonon coupling and its momentum dependence from resonant inelastic
x-ray scattering (RIXS) spectra based on the detuning of the incident photon
energy away from an absorption resonance. We apply it to the cuprate parent
compound NdBaCuO and find that the electronic coupling to the
oxygen half-breathing phonon mode is strongest at the Brillouin zone boundary,
where it amounts to eV, in agreement with previous studies. In
principle, this method is applicable to any absorption resonance suitable for
RIXS measurements and will help to define the contribution of lattice
vibrations to the peculiar properties of quantum materials.Comment: 6 pages, 3 figure
Determining the Electron-Phonon Coupling in Superconducting Cuprates by Resonant Inelastic X-ray Scattering: Methods and Results on NdBaCuO
The coupling between lattice vibration quanta and valence electrons can
induce charge density modulations and decisively influence the transport
properties of materials, e.g. leading to conventional superconductivity. In
high critical temperature superconductors, where electronic correlation is the
main actor, the actual role of electron-phonon coupling (EPC) is being
intensely debated theoretically and investigated experimentally. We present an
in-depth study of how the EPC strength can be obtained directly from resonant
inelastic x-ray scattering (RIXS) data through the theoretical approach derived
by Ament et al. [EPL 95, 27008 (2011)]. The role of the model parameters (e.g.
phonon energy , intermediate state lifetime , EPC matrix
element , and detuning energy ) is thoroughly analyzed, providing
general relations among them that can be used to make quantitative estimates of
the dimensionless EPC without detailed microscopic
modeling. We then apply these methods to very high resolution Cu edge
RIXS spectra of three NdBaCuO films. For the
insulating antiferromagnetic parent compound the value of as a function of
the in-plane momentum transfer is obtained for Cu-O bond-stretching (breathing)
and bond-bending (buckling) phonon branches. For the underdoped and the nearly
optimally doped samples, the effects of Coulomb screening and of
charge-density-wave correlations on are assessed. In light of the
anticipated further improvements of the RIXS experimental resolution, this work
provides a solid framework for an exhaustive investigation of the EPC in
cuprates and other quantum materials.Comment: 21 pages, 16 figure
Determining the electron-phonon coupling in superconducting cuprates by resonant inelastic x-ray scattering: Methods and results on Nd1+xBa2-xCu3O7-ÎŽ
The coupling between lattice vibration quanta and valence electrons can induce charge-density modulations and decisively influence the transport properties of materials, e.g., leading to conventional superconductivity. In high-critical-temperature superconductors, where electronic correlation is the main actor, the actual role of electron-phonon coupling (EPC) is being intensely debated theoretically and investigated experimentally. We present an in-depth study of how the EPC strength can be obtained directly from resonant inelastic x-ray scattering (RIXS) data through the theoretical approach derived by Ament et\ua0al. [Europhys. Lett. 95, 27008 (2011)]. The role of the model parameters (e.g., phonon energy Ï0, intermediate state lifetime 1/Î, EPC matrix element M, and detuning energy Ω) is thoroughly analyzed, providing general relations among them that can be used to make quantitative estimates of the dimensionless EPC g=(M/Ï0)2 without detailed microscopic modeling. We then apply these methods to very high-resolution Cu L3-edge RIXS spectra of three Nd1+xBa2âxCu3O7âÎŽ films. For the insulating antiferromagnetic parent compound, the value of M as a function of the in-plane momentum transfer is obtained for Cu-O bond-stretching (breathing) and bond-bending (buckling) phonon branches. For the underdoped and the nearly optimally doped samples, the effects of Coulomb screening and of charge-density-wave correlations on M are assessed. In light of the anticipated further improvements of the RIXS experimental resolution, this work provides a solid framework for an exhaustive investigation of the EPC in cuprates and other quantum materials
Influence of apical oxygen on the extent of in-plane exchange interaction in cuprate superconductors
In high Tc superconductors the magnetic and electronic properties are
determined by the probability that valence electrons virtually jump from site
to site in the CuO2 planes, a mechanism opposed by on-site Coulomb repulsion
and favored by hopping integrals. The spatial extent of the latter is related
to transport properties, including superconductivity, and to the dispersion
relation of spin excitations (magnons). Here, for three antiferromagnetic
parent compounds (single-layer Bi2Sr0.99La1.1CuO6+delta, double-layer
Nd1.2Ba1.8Cu3O6 and infinite-layer CaCuO2) differing by the number of apical
atoms, we compare the magnetic spectra measured by resonant inelastic x-ray
scattering over a significant portion of the reciprocal space and with
unprecedented accuracy. We observe that the absence of apical oxygens increases
the in-plane hopping range and, in CaCuO2, it leads to a genuine 3D
exchange-bond network. These results establish a corresponding relation between
the exchange interactions and the crystal structure, and provide fresh insight
into the materials dependence of the superconducting transition temperature.Comment: 9 pages, 4 figures, 1 Table, 42 reference
Hypoinsulinaemic, hypoketotic hypoglycaemia due to mosaic genetic activation of PI3-kinase.
OBJECTIVE: Genetic activation of the insulin signal-transducing kinase AKT2 causes syndromic hypoketotic hypoglycaemia without elevated insulin. Mosaic activating mutations in class 1A phospatidylinositol-3-kinase (PI3K), upstream from AKT2 in insulin signalling, are known to cause segmental overgrowth, but the metabolic consequences have not been systematically reported. We assess the metabolic phenotype of 22 patients with mosaic activating mutations affecting PI3K, thereby providing new insight into the metabolic function of this complex node in insulin signal transduction. METHODS: Three patients with megalencephaly, diffuse asymmetric overgrowth, hypoketotic, hypoinsulinaemic hypoglycaemia and no AKT2 mutation underwent further genetic, clinical and metabolic investigation. Signalling in dermal fibroblasts from one patient and efficacy of the mTOR inhibitor Sirolimus on pathway activation were examined. Finally, the metabolic profile of a cohort of 19 further patients with mosaic activating mutations in PI3K was assessed. RESULTS: In the first three patients, mosaic mutations in PIK3CA (p.Gly118Asp or p.Glu726Lys) or PIK3R2 (p.Gly373Arg) were found. In different tissue samples available from one patient, the PIK3CA p.Glu726Lys mutation was present at burdens from 24% to 42%, with the highest level in the liver. Dermal fibroblasts showed increased basal AKT phosphorylation which was potently suppressed by Sirolimus. Nineteen further patients with mosaic mutations in PIK3CA had neither clinical nor biochemical evidence of hypoglycaemia. CONCLUSIONS: Mosaic mutations activating class 1A PI3K cause severe non-ketotic hypoglycaemia in a subset of patients, with the metabolic phenotype presumably related to the extent of mosaicism within the liver. mTOR or PI3K inhibitors offer the prospect for future therapy
Comparative examinations of the expulsion time of the foetal membranes in various horse breeds
SUMMARY
Being the most important link between the foetus and the dam, the placenta
has a pivotal role in maintaining the integrity of gestation and in ensuring foetal
well-being and development. Despite the fact that placental anomalies markedly
affect the status of the foal and the mare, thorough and critical assessment of the
intrauterine and postpartum placental parameters are often neglected. The aim
of this article is to highlight the importance of placental examination. Data from
106 pregnancies in 5 different breeds were collected, analyzed and interpreted in
the light of most recent publications. The mean±SD time of the placental passage
in Kisberi, Gidran, Hungarian draft, Thoroughbred and Arabians were 41 ± 32.330,
45.67 ± 39.727, 310.55 ± 351.442, 33.04 ± 17.750 and 56.86 ± 20.292 respectively
Influence of apical oxygen on the extent of in-plane exchange interaction in cuprate superconductors
In high-Tc superconductors the magnetic and electronic properties are determined by the probability that valence electrons
jump virtually from site to site in the CuO2 planes, a mechanism opposed by on-site Coulomb repulsion and favoured by
hopping integrals. The spatial extent of the latter is related to transport properties, including superconductivity, and to
the dispersion relation of spin excitations (magnons). Here, for three antiferromagnetic parent compounds (single-layer
Bi2Sr0.9La1.1CuO6C , double-layer Nd1.2Ba1.8Cu3O6 and infinite-layer CaCuO2) diering by the number of apical atoms, we
compare the magnetic spectra measured by resonant inelastic X-ray scattering over a significant portion of the reciprocal
space and with unprecedented accuracy.We observe that the absence of apical oxygens increases the in-plane hopping range
and, in CaCuO2, it leads to a genuine three-dimensional (3D) exchange-bond network. These results establish a corresponding
relation between the exchange interactions and the crystal structure, and provide fresh insight into the materials dependence
of the superconducting transition temperature