Search for diphoton events with large missing transverse energy in 6.3 fb(-1) of pp collisions at √s=1.96 TeV

We report a search for diphoton events with large missing transverse energy produced in pp collisions at √s=1.96  TeV. The data were collected with the D0 detector at the Fermilab Tevatron Collider and correspond to 6.3  fb(-1) of integrated luminosity. The observed missing transverse energy distribution is well described by the standard model prediction, and 95% C.L. limits are derived on two realizations of theories beyond the standard model. In a gauge-mediated supersymmetry breaking scenario, the breaking scale Λ is excluded for Λ<124  TeV. In a universal extra dimension model including gravitational decays, the compactification radius R(c) is excluded for R(c)(-1)<477  GeV.

Search for new fermions ("quirks") at the Fermilab Tevatron collider

We report results of a search for particles with anomalously high ionization in events with a high transverse energy jet and large missing transverse energy in 2.4 fb⁻¹ of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron pp collider. Production of such particles (quirks) is expected in scenarios with extra QCD-like SU(N) sectors, and this study is the first dedicated search for such signatures. We find no evidence of a signal and set a lower mass limit of 107, 119, and 133 GeV for the mass of a charged quirk with strong dynamics scale Λ in the range from 10 keV to 1 MeV and N=2, 3, and 5, respectively.

Search for events with leptonic jets and missing transverse energy in pp collisions at √s=1.96 TeV

We present the first search for pair production of isolated jets of charged leptons in association with a large imbalance in transverse energy in pp collisions using 5.8 fb⁻¹ of integrated luminosity collected by the D0 detector at the Fermilab Tevatron Collider. No excess is observed above the standard model background, and the result is used to set upper limits on the production cross section of pairs of supersymmetric chargino and neutralino particles as a function of "dark-photon" mass, where the dark photon is produced in the decay of the lightest supersymmetric particle.

Search for sneutrino production in eμ final states in 5.3 fb-1 of pp collisions at square root s =1.96 TeV

We report the results of a search for R parity violating (RPV) interactions leading to the production of supersymmetric sneutrinos decaying into eμ final states using 5.3 fb-1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Having observed no evidence for production of eμ resonances, we set direct bounds on the RPV couplings λ311' and λ312 as a function of sneutrino mass.

Intravenous administration of bone marrow mesenchymal stem cells benefits experimental autoimmune myasthenia gravis mice through an immunomodulatory action

Mesenchymal stem cells (MSC) are potent in immunomodulation. It has been proven that MSC functioned to correct immune disorder in several immune diseases. Here, we tested the hypothesis that MSC from human bone marrow (hMSC) can provide a potential therapy for experimental autoimmune myasthenia gravis (EAMG). EAMG mice model was established by subcutaneous injection of synthetic analogue of acetylcholine receptor (AchR), then, hMSC were intravenously delivered into these mice repeatedly. The results showed that hMSC could specifically home to spleen tissue and hMSC treatment significantly improved the functional deficits of EAMG mice. In addition, AchR antibody level was dramatically decreased in cell-treated group when compared with untreated control on 10 days after the second cell injection. Moreover, both in vivo and in vitro mixed lymphocyte proliferation assays revealed that hMSC could definitely inhibit the proliferation of AchR-specific lymphocyte. In conclusion, our study demonstrated that hMSC treatment was therapeutically useful in autoimmune myasthenia gravis mice, and the underlying mechanism may relate with their immunomodulatory potential.

Cautionary note: linewidth effect in dynamic NMR

In using NMR spectroscopy to evaluate the effects of kinetic processes taking place in the solute molecules being studied, one must estimate the inherent width w of each line, which is hidden from view throughout the kinetic thermal region due to the line-width broadening effected by the processes. We have herein built a self-consistent model function w(T) to attempt to evaluate the variation in the Arrhenius activation energy obtained with the model parameters present in w(T). As it turns out, a sizable number of such line-width parameters yields excellent spectral fits, and these lead to a considerable range of possible activation energies.

Assessment of the Risk of Rupture of Intracranial Aneurysms using Three-Dimensional Cerebral Digital Subtraction Angiography

The aim of this study was to develop an improved binary logistic regression model for predicting the risk of intracranial aneurysm rupture. A cohort of patients ( n = 37) with aneurysms underwent three-dimensional digital subtraction angiography examination to measure several morphological parameters of the aneurysm. The aspect ratio (height/neck size) and the size ratio (length/mean diameter of parent vessel) were also calculated. All the morphological parameters combined with the aneurysm location and the patient's baseline data were used to derive a backward binary logistic regression model. In order to validate the model, it was applied to another independent cohort of 19 patients with aneurysms. The model had sensitivity, specificity and accuracy of 84.6%, 66.7% and 78.9%, respectively. This binary logistic regression model of aneurysm rupture risk identified the status of an aneurysm with high accuracy and could form the basis of more complex models in the future.

Electronic structure of double perovskite A2FeReO6 (A = Ba and Ca): interplay between spin-orbit interaction, electron correlation, and lattice distortion

We have investigated the electronic structure of double perovskites, Ba(2)FeReO(6) (metallic) and Ca(2)FeReO(6) (insulating) using optical and x-ray absorption spectroscopy. By comparing the experimental results with the density functional theory calculations, we found that the electronic structure of Ba(2)FeReO(6) could be determined from the interaction of the electron correlation and spin-orbit coupling. On the other hand, for Ca(2)FeReO(6), the lattice distortion and electron correlation are important in determining the electronic structure. Additionally, the insulating gap in Ca(2)FeReO(6) is realized by the spin-orbit coupling. Our work shows that the subtle interplay of the spin-orbit interaction, electron correlation, and lattice distortion should be taken into account to understand the electronic structure of the 5d transition metal oxides.