Unusual temperature dependence of band dispersion in Ba(Fe(1-x)Ru(x))2As2 and its consequences for antiferromagnetic ordering

We have performed detailed studies of the temperature evolution of the electronic structure in Ba(Fe(1-x)Ru(x))2As2 using Angle Resolved Photoemission Spectroscopy (ARPES). Surprisingly, we find that the binding energy of both hole and electron bands changes significantly with temperature in pure and Ru substituted samples. The hole and electron pockets are well nested at low temperature in unsubstituted (BaFe2As2) samples, which likely drives the spin density wave (SDW) and resulting antiferromagnetic order. Upon warming, this nesting is degraded as the hole pocket shrinks and the electron pocket expands. Our results demonstrate that the temperature dependent nesting may play an important role in driving the antiferromagnetic/paramagnetic phase transition.Comment: 5 pages, 6 figure

Full length interleukin 33 aggravates radiation-induced skin reaction

The interleukin (IL)-1 family member IL-33 has been described as intracellular alarmin with broad roles in wound healing, skin inflammation but also autoimmunity. Its dichotomy between full length (fl) IL-33 and the mature (m) form of IL-33 and its release by necrosis is still not fully understood. Here, we compare functional consequences of both forms in the skin in vivo, and therefore generated two lines of transgenic mice which selectively overexpress mmIL-33 and flmIL-33 in basal keratinocytes. Transgene mRNA was expressed at high level in skin of both lines but not in organs due to the specific K14 promoter. We could demonstrate that transgenic overexpression of mmIL-33 in murine keratinocytes leads to a spontaneous skin inflammation as opposed to flmIL-33. K14-mmIL-33 mice synthesize and secrete high amounts of mmIL-33 along with massive cutaneous manifestations, like increased epidermis and dermis thickness, infiltration of mast cells in the epidermis and dermis layers and marked hyperkeratosis. Using skin inflammation models such as IL-23 administration, imiquimod treatment, or mechanical irritation did not lead to exacerbated inflammation in the K14-flmIL-33 strain. As radiation induces a strong dermatitis due to apoptosis and necrosis, we determined the effect of fractionated radiation (12 Gy, 4 times). In comparison to wild-type mice, an increase in ear thickness in flmIL-33 transgenic mice was observed 25 days after irradiation. Macroscopic examination showed more severe skin symptoms in irradiated ears compared to controls. In summary, secreted mmIL-33 itself has a potent capacity in skin inflammation whereas fl IL-33 is limited due to its intracellular retention. During tissue damage, fl IL-33 exacerbated radiation-induced skin reaction

Radiation Dose–Volume Effects in the Brain

We have reviewed the published data regarding radiotherapy (RT)-induced brain injury. Radiation necrosis appears a median of 1–2 years after RT; however, cognitive decline develops over many years. The incidence and severity is dose and volume dependent and can also be increased by chemotherapy, age, diabetes, and spatial factors. For fractionated RT with a fraction size of 80 Gy. For large fraction sizes (≥2.5 Gy), the incidence and severity of toxicity is unpredictable. For single fraction radiosurgery, a clear correlation has been demonstrated between the target size and the risk of adverse events. Substantial variation among different centers’ reported outcomes have prevented us from making toxicity–risk predictions. Cognitive dysfunction in children is largely seen for whole brain doses of ≥18 Gy. No substantial evidence has shown that RT induces irreversible cognitive decline in adults within 4 years of RT

A measurement of the W boson mass using large rapidity electrons

We present a measurement of the W boson mass using data collected by the D0 experiment at the Fermilab Tevatron during 1994--1995. We identify W bosons by their decays to e-nu final states where the electron is detected in a forward calorimeter. We extract the W boson mass, Mw, by fitting the transverse mass and transverse electron and neutrino momentum spectra from a sample of 11,089 W -> e nu decay candidates. We use a sample of 1,687 dielectron events, mostly due to Z -> ee decays, to constrain our model of the detector response. Using the forward calorimeter data, we measure Mw = 80.691 +- 0.227 GeV. Combining the forward calorimeter measurements with our previously published central calorimeter results, we obtain Mw = 80.482 +- 0.091 GeV

Differential Production Cross Section of Z Bosons as a Function of Transverse Momentum at sqrt{s}=1.8 TeV

We present a measurement of the transverse momentum distribution of Z bosons produced in ppbar collisions at sqrt{s}=1.8 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider during 1994--1996. We find good agreement between our data and a current resummation calculation. We also use our data to extract values of the non-perturbative parameters for a particular version of the resummation formalism, obtaining significantly more precise values than previous determinations.Comment: 10 pages, 2 figures, submitted to Phys. Rev. Letters v2 has margin error correcte

Search for Charged Higgs Bosons in Decays of Top Quark Pairs

We present a search for charged Higgs bosons in decays of pair-produced top quarks using 109.2 +- 5.8 pb^-1 of data recorded from ppbar collisions at sqrt{s} = 1.8 TeV by the D0 detector during 1992-96 at the Fermilab Tevatron. No evidence is found for charged Higgs production, and most parts of the [m(H+),tan(beta)] parameter space where the decay t -> bH+ has a branching fraction close to or larger than that for t -> bW+ are excluded at 95% confidence level. Assuming m(t) = 175 GeV and sigma(ppbar -> ttbar) = 5.5 pb, for m(H+) = 60 GeV, we exclude tan(beta) 40.9.Comment: 11 pages, 3 figures, submitted to PR

Search for Squarks and Gluinos in Events Containing Jets and a Large Imbalance in Transverse Energy

Using data corresponding to an integrated luminosity of 79 pb-1, D0 has searched for events containing multiple jets and large missing transverse energy in pbar-p collisions at sqrt(s)=1.8 TeV at the Fermilab Tevatron collider. Observing no significant excess beyond what is expected from the standard model, we set limits on the masses of squarks and gluinos and on the model parameters m_0 and m_1/2, in the framework of the minimal low-energy supergravity models of supersymmetry. For tan(beta) = 2 and A_0 = 0, with mu < 0, we exclude all models with m_squark < 250 GeV/c^2. For models with equal squark and gluino masses, we exclude m < 260 GeV/c^2.Comment: 10 pages, 3 figures, Submitted to PRL, Fixed typo on page bottom of p. 6 (QCD multijet background is 35.4 events

Search for bottom squarks in pbarp collisions at sqrt(s)=1.8 TeV

We report on a search for bottom squarks produced in pbarp collisions at sqrt(s) = 1.8 TeV using the D0 detector at Fermilab. Bottom squarks are assumed to be produced in pairs and to decay to the lightest supersymmetric particle (LSP) and a b quark with branching fraction of 100%. The LSP is assumed to be the lightest neutralino and stable. We set limits on the production cross section as a function of bottom squark mass and LSP mass.Comment: 5 pages, Latex. submitted 3-12-1999 to PRD - Rapid Communicatio

Nanostructuring Strategies To Increase the Photoelectrochemical Water Splitting Activity of Silicon Photocathodes

Photoelectrochemical water splitting is a promising route for sustainable hydrogen production. Herein, we demonstrate a photoelectrode motif that enables a nanostructured large-surface area electrocatalyst without requiring a nanostructured semiconductor surface with the goal of promoting electrocatalysis while minimizing surface recombination. We compare the photoelectrochemical H2 evolution activity of two silicon photocathode nanostructuring strategies: (1) direct nanostructuring of the silicon surface and (2) incorporation of nanostructured zinc oxide to increase the electrocatalyst surface area on planar silicon. We observed that silicon photocathodes that utilized nanostructured ZnO supports outperformed nanostructured silicon electrodes by ∼50 mV at open circuit under 1 sun illumination and demonstrated comparable electrocatalytic activity