1,400 research outputs found
Search for dark matter in the hidden-photon sector with a large spherical mirror
If dark matter consists of hidden-sector photons which kinetically mix with
regular photons, a tiny oscillating electric-field component is present
wherever we have dark matter. In the surface of conducting materials this
induces a small probability to emit single photons almost perpendicular to the
surface, with the corresponding photon frequency matching the mass of the
hidden photons. We report on a construction of an experimental setup with a
large ~14 m2 spherical metallic mirror that will allow for searches of
hidden-photon dark matter in the eV and sub-eV range by application of
different electromagnetic radiation detectors. We discuss sensitivity and
accessible regions in the dark matter parameter space.Comment: 9 pages, proceeding of the 34th International Cosmic Ray Conference
(ICRC), July 30 - August 6, 2015, The Hague, The Netherland
Search for hidden-photon dark matter with the FUNK experiment
Many extensions of the Standard Model of particle physics predict a parallel
sector of a new U(1) symmetry, giving rise to hidden photons. These hidden
photons are candidate particles for cold dark matter. They are expected to
kinetically mix with regular photons, which leads to a tiny oscillating
electric-field component accompanying dark matter particles. A conducting
surface can convert such dark matter particles into photons which are emitted
almost perpendicularly to the surface. The corresponding photon frequency
follows from the mass of the hidden photons. In this contribution we present a
preliminary result on a hidden photon search in the visible and near-UV
wavelength range that was done with a large, 14 m2 spherical metallic mirror
and discuss future dark matter searches in the eV and sub-eV range by
application of different detectors for electromagnetic radiation.Comment: Contribution to the 35th International Cosmic Ray Conference
ICRC2017, 10 to 20 July, 2017, Bexco, Busan, Korea. arXiv admin note: text
overlap with arXiv:1711.0296
Hepatitis E virus: Efficacy of pasteurization of plasmaâderived VWF/FVIII concentrate determined by pig bioassay
Background Hepatitis E virus (HEV) is the leading cause of acute hepatitis throughout the world. Increasing blood component transfusion-associated HEV infections highlight the need for reliable virus inactivation procedures for plasma derivatives from pooled plasma donations.
Study Design and Methods An animal infection study was conducted to evaluate the efficiency of HEV inactivation by pasteurization during the manufacturing process of the von Willebrand Factor/Factor VIII (VWF/FVIII) concentrate Haemate P/Humate-P (CSL Behring, Marburg, Germany). For this purpose, groups of pigs were inoculated with stabilized VWF/FVIII intermediate spiked with HEV-positive liver homogenate and exposed to increasing incubation times of 0, 3, 6, and 10 h at 60 degrees C. Animals were evaluated for virus replication over 27 days and in a subsequent trial over 92 days.
Results Virus replication was detected in animals up to the 6-h pasteurization group. In contrast, pasteurization for 10 h did not reveal virus detection when the observation period was 27 days. In an additional experiment using the 10-h pasteurized material, two individuals started virus excretion and seroconverted when the observation period was extended to 92 days. Based on the total infection rate (2 of 12) of the animals inoculated with the sample pasteurized for 10 h, a virus reduction factor of at least 4.7 log(10) is calculated.
Conclusion This study demonstrates that pasteurization at 60 degrees C for 10 h of an HEV-positive plasma derivative leads to the effective reduction of infectivity, resulting in a VWF/FVIII product with an appropriate margin of safety for HEV
Operator Projection Theory for Electron Differentiation in Underdoped Cuprate Superconductors
Metals approaching the Mott insulator generate a new hierarchy in the
electronic structure accompanied by a momentum dependent electron
differentiation, beyond the Mott-Hubbard, Brinkman-Rice and Slater pictures of
the Mott transition. To consider such nonlinear phenomenon, we develop an
analytic nonperturbative theory based on operator projections combined with a
self-consistent treatment of the low-energy excitations. This reproduces the
formation of the Hubbard bands, Mott gap, spin fluctuations, mass divergence,
diverging charge compressibility, and strongly renormalized flat and damped
dispersion similar to angle-resolved photoemission data in high-T_c cuprates.
Main structures in electronic spectra show a remarkable similarity to numerical
results.Comment: 11 pages, presented at ``Spectroscopies of Novel Superconductors
2001'
Rapid disease progression on immune checkpoint inhibitors in young patients with stage IV melanoma
BackgroundImmune checkpoint inhibitors (ICIs) are the standard of care for metastatic cutaneous melanoma (mCM) patients, but their efficacy in young adults aged less than 40 years remains unclear.Materials and methodsWe retrospectively analyzed 303 stage IV melanoma patients of different ages treated with nivolumab, pembrolizumab, or ipilimumab plus nivolumab combination therapy. Clinical data and blood values such as LDH, CRP, and absolute immune cell counts were retrieved from the medical records. Pre-treatment serum concentrations of soluble immune checkpoint proteins were measured using ELISA. In addition, information on frequencies of various T cell subsets in the peripheral blood was collected from a previously reported study (ELEKTRA). Patient characteristics and clinical information was correlated with PFS and OS using univariate and multivariate cox regression analysis.ResultsOf 303 patients, 33 (11%) were †40 years old. The older patients had a median age of 64 (95% CI: 61â66). Concerning prognostic parameters, there was no difference between the age groups, e.g., in gender, LDH, or the existence of brain or liver metastases. Patients aged †40 years [p = 0.014; HR: 1.6 (95% CI: 1.1â2.4)], presence of liver metastases [p = 0.016; HR: 1.4 (95% CI: 1.0â1.9)], line of ICI treatment [p = 0.009; HR: 1.4 (1.0â1.9)], elevated LDH [p = 0.076; HR: 1.3 (95% CI: 0.97â1.8)], and brain metastasis [p = 0.080; HR: 1.3 (95% CI: 0.97â1.7)], were associated with shorter PFS in univariate analysis. Multivariate analysis revealed that the patientâs age (†40 years) remains a high-risk factor upon adjusting for all potential confounders [p = 0.067; HR: 1.5 (95% CI: 0.97â2.3)]. Blood parameters revealed that patients †40 years have relatively higher frequencies of activated CD4 T cells (CD4 + Ki67 + CD4 + ICOS +) in the blood, and significantly lower number of basophils and CD45RA- memory T cells, compared to patients above 40 years (p < 0.05). In addition, patients †40 years experiencing disease progression within 6 months of ICI treatment had increased concentrations of sPDL1 (p = 0.05) and sTIM3 (p = 0.054) at baseline.ConclusionYoung patients with stage IV melanoma may experience shorter progression-free survival upon ICI treatment compared to patients above 40 years and are characterized by fewer basophils and memory T cells in the blood
Search for dark photons as candidates for Dark Matter with FUNK
An additional U(1) symmetry predicted in theories beyond the Standard Model of particle physics can give rise to hidden (dark) photons. Depending on the mass and density of these hidden photons, they could account for a large fraction of the Dark Matter observed in the Universe. When passing through an interface of materials with different dielectric properties, hidden photons are expected to produce a tiny flux of photons. The wavelength of these photons is directly related to the mass of the hidden photons. In this contribution we report on measurements covering the visible and near-UV spectrum, corresponding to a dark photon mass in the eV range. The data were taken with the FUNK experiment using a spherical mirror of ~14m2 total area built up of 36 aluminum segments
Limits from the FUNK experiment on the mixing strength of hidden-photon dark matter in the visible and near-ultraviolet wavelength range
We present results from the FUNK experiment in the search for hidden-photon dark matter. Near the surface of a mirror, hidden photons may be converted into ordinary photons. These photons are emitted perpendicularly to the surface and have an energy equal to the mass of the dark matter hidden photon. Our experimental setup consists of a large, spherical mirror with an area of more than 14ââm2, which concentrates the emitted photons into its central point. Using a detector sensitive to visible and near-UV photons, we can exclude a kinetic-mixing coupling of stronger than Ïâ10â12 in the mass range of 2.5 to 7 eV, assuming hidden photons comprise all of the dark matter. The experimental setup and analysis used to obtain this limit are discussed in detai
LETSGO: A spacecraft-based mission to accurately measure the solar angular momentum with frame-dragging
LETSGO (LEnse-Thirring Sun-Geo Orbiter) is a proposed space-based mission
involving the use of a spacecraft moving along a highly eccentric heliocentric
orbit perpendicular to the ecliptic. It aims to accurately measure some
important physical properties of the Sun and to test some post-Newtonian
features of its gravitational field by continuously monitoring the Earth-probe
range. Preliminary sensitivity analyses show that, by assuming a cm-level
accuracy in ranging to the spacecraft, it would be possible to detect, in
principle, the Lense-Thirring effect on it at a 10^-3-10^-4 level over a
timescale of 2 yr, while the larger Schwarzschild component of the solar
gravitational field may be sensed with a relative accuracy of about 10^-8-10^-9
during the same temporal interval. The competing range perturbation due to the
non-sphericity of the Sun would be a source of systematic error, but it turns
out that all the three dynamical features of motion examined affect the
Earth-probe range in different ways, allowing for a separation in data
analyses. The high eccentricity would help in reducing the impact of the
non-gravitational perturbations whose impact would certainly be severe when
LETSGO would approach the Sun at just a few solar radii. Further studies should
be devoted to investigate both the consequences of the non-conservative forces
and the actual measurability of the effects of interest by means of extensive
numerical data simulations, parameter estimations and covariance analyses. Also
an alternative, fly-by configuration is worth of consideration.Comment: LaTex2e, double column, 19 pages, 3 figures, 3 tables, 97 references.
Accepted for publication in Acta Astronautica. Proof corrections inserte
A keratin scaffold regulates epidermal barrier formation, mitochondrial lipid composition, and activity.
Keratin intermediate filaments (KIFs) protect the epidermis against mechanical force, support strong adhesion, help barrier formation, and regulate growth. The mechanisms by which type I and II keratins contribute to these functions remain incompletely understood. Here, we report that mice lacking all type I or type II keratins display severe barrier defects and fragile skin, leading to perinatal mortality with full penetrance. Comparative proteomics of cornified envelopes (CEs) from prenatal KtyI(-/-) and KtyII(-/-)(K8) mice demonstrates that absence of KIF causes dysregulation of many CE constituents, including downregulation of desmoglein 1. Despite persistence of loricrin expression and upregulation of many Nrf2 targets, including CE components Sprr2d and Sprr2h, extensive barrier defects persist, identifying keratins as essential CE scaffolds. Furthermore, we show that KIFs control mitochondrial lipid composition and activity in a cell-intrinsic manner. Therefore, our study explains the complexity of keratinopathies accompanied by barrier disorders by linking keratin scaffolds to mitochondria, adhesion, and CE formation
- âŠ