Production of muons from heavy flavor decays at forward rapidity in pp and Pb-Pb collisions at sqrt[s(NN)]=2.76 TeV

The ALICE Collaboration has measured the inclusive production of muons from heavy-flavor decays at forward rapidity, 2.5<y<4, in pp and Pb-Pb collisions at sqrt[s(NN)]=2.76  TeV. The p(t)-differential inclusive cross section of muons from heavy-flavor decays in pp collisions is compared to perturbative QCD calculations. The nuclear modification factor is studied as a function of p(t) and collision centrality. A weak suppression is measured in peripheral collisions. In the most central collisions, a suppression of a factor of about 3-4 is observed in 6<p(t)<10  GeV/c. The suppression shows no significant p(t) dependence.

Germ cell-specific disruption of the Meig1 gene causes impaired spermiogenesis in mice

Meiosis expressed gene 1 (Meig1) was originally identified in a search for mammalian genes potentially involved in meiosis. Seven mouse Meig1 transcripts with the same coding region, but different 5'-UTRs, have been identified. These transcripts have different tissue distributions, two are only present in the testis. In the testis, Meig1 is present in germ cells and Sertoli cells. A Meig1 conditional knockout model has been generated. When Meig1 was inactivated globally by crossing with Cmv-Cre transgenic mice, the Meig1-deficient males were sterile due to severe spermiogenic defects, and had no obvious defects in meiosis. To further study its role in individual cell types in the testis, the Meig1(flox) mice were crossed with Hsp2a-Cre, Prm-Cre, and Amh-Cre mice, in which the Cre recombinase is driven by the heat shock protein 2 (Hsp2a) gene promoter (expressed in spermatocytes), the protamine 1 gene promoter (expressed in post-meiotic spermatids) and the anti-Mullerian hormone (Amh) gene promoter (expressed in Sertoli cells) respectively. Both Meig1 mRNA and protein were undetectable in testis of the Hsp2a-Cre; Meig1(flox/flox) mice and all the mutant adult males tested were sterile. This phenotype mirrors that of the Cmv-Cre; Meig1(flox/flox) mice. Even though the total testicular Meig1 mRNA and protein expression levels were dramatically reduced in testis of the Prm-Cre; Meig1(flox/flox) males, all the mice tested were fertile, and there was no significant difference in sperm count and sperm motility compared with age-matched Meig1(flox/flox) male mice. Disruption of Meig1 in the Sertoli cells did not affect the MEIG1 protein expression. Amh-Cre; Meig1(flox/flox) males were fertile, and produced the same amount of spermatozoa as age-matched Meig1(flox/flox) mice. The testicular histology was also normal. Our results indicate that MEIG1 regulates spermiogenesis through effects in germ cells alone, and that the Meig1 gene must be active during a discrete period in spermatogenesis after which it is dispensable.

J/ψ suppression at forward rapidity in Pb-Pb collisions at √s(NN) = 2.76 TeV

The ALICE experiment has measured the inclusive J/ψ production in Pb-Pb collisions at √s(NN) = 2.76 TeV down to zero transverse momentum in the rapidity range 2.5 < y < 4. A suppression of the inclusive J/ψ yield in Pb-Pb is observed with respect to the one measured in pp collisions scaled by the number of binary nucleon-nucleon collisions. The nuclear modification factor, integrated over the 0%-80% most central collisions, is 0.545 ± 0.032(stat) ± 0.083(syst) and does not exhibit a significant dependence on the collision centrality. These features appear significantly different from measurements at lower collision energies. Models including J/ψ production from charm quarks in a deconfined partonic phase can describe our data.

On the equivalence of posterior inference based on retrospective and prospective likelihoods: application to a case-control study of colorectal cancer

The paper develops a class of priors that leads to equivalent posterior inference for odds ratio parameters based on prospective and retrospective models for categorical response data. The results are applicable to both unmatched and matched case-control studies. The results hold for a general class of link functions for categorical response. The proposed method can accommodate multiple and possibly ordered disease states. The results are applied to the analysis of discrete subtypes in an ongoing case-control study of colorectal cancer. A simulation study illustrates the need for carefully considering prior choices in Bayesian analysis of data collected under retrospective design.

Particle-yield modification in jetlike azimuthal dihadron correlations in Pb-Pb collisions at √s(NN)=2.76 TeV

The yield of charged particles associated with high-p(t) trigger particles (8<p(t)<15 GeV/c) is measured with the ALICE detector in Pb-Pb collisions at √s(NN)=2.76 TeV relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jetlike correlation peaks in azimuthal dihadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta p(t)>3 GeV/c on the away side drops to about 60% of that observed in pp collisions, while on the near side a moderate enhancement of 20%-30% is found.

Influence of serum leptin levels on future overweight risk in Korean children

BACKGROUND AND AIMS

Leptin is an important regulator of energy metabolism. It is considered to be positively related to body adiposity and metabolic disorders in obese adults and children. The purpose of this study was to evaluate the relationship between baseline circulating leptin, insulin and adiponectin levels and future overweight and metabolic risks in a paediatric population-based cohort.

METHODS AND RESULTS

First-grade students, who entered elementary school at age 7 years in Gwacheon, a Korean city, were enrolled in this cohort study, and followed from 1st grade to 5th grade. Annual physical examinations from 2005 to 2009 were performed. In 2006, the levels of serum glucose, insulin, leptin and adiponectin and lipid profiles were examined. In 2008, the above parameters, except for adiponectin, were measured again in 381 children (202 boys and 179 girls) who participated. In 2006, 10.2% of the children were overweight (body mass index (BMI) ≥ 85th percentile), and after 2 years, an additional 3% became overweight. Compared with insulin and adiponectin, leptin was most highly associated with current and future BMI, and percent body fat. Boys in the highest tertile for initial leptin (T3) showed the highest prevalence of overweight and metabolic risk scores among three leptin tertile groups. Girls showed the same trends as boys. High initial leptin levels could be predictive of greater future BMI and metabolic risk score (p < 0.001).

CONCLUSION

These results suggest that elevated serum leptin concentrations among the childhood population could be a marker for future BMI and metabolic disorders.

J/ψ polarization in pp collisions at √s=7 TeV

The ALICE Collaboration has studied J/ψ production in pp collisions at √s=7 TeV at the LHC through its muon pair decay. The polar and azimuthal angle distributions of the decay muons were measured, and results on the J/ψ polarization parameters λ(θ) and λ(φ) were obtained. The study was performed in the kinematic region 2.5<y<4, 2<p(t)<8 GeV/c, in the helicity and Collins-Soper reference frames. In both frames, the polarization parameters are compatible with zero, within uncertainties.

MicroRNA-34a modulates cytoskeletal dynamics through regulating RhoA/Rac1 cross-talk in chondroblasts

MicroRNAs (miRNAs) have been implicated in various cellular processes, such as cell fate determination, cell death, and tumorigenesis. In the present study, we investigated the role of miRNA-34a (miR-34a) in the reorganization of the actin cytoskeleton, which is essential for chondrocyte differentiation. miRNA arrays to identify genes that appeared to be up-regulated or down-regulated during chondrogenesis were applied with chondrogenic progenitors treated with JNK inhibitor. PNA-based antisense oligonucleotides and miRNA precursor were used for investigation of the functional roles of miR-34a. We found that, in chick chondroprogenitors treated with JNK inhibitor, which suppresses chondrogenic differentiation, the expression levels of miR-34a and RhoA1 are up-regulated through modulation of Rac1 expression. Blockade of miR-34a via the use of PNA-based antisense oligonucleotides was associated with decreased protein expression of RhoA (a known modulator of stress fiber expression), down-regulation of stress fibers, up-regulation of Rac1, and recovery of protein level of type II collagen. miR-34a regulates RhoA/Rac1 cross-talk and negatively modulates reorganization of the actin cytoskeleton, which is one of the essential processes for establishing chondrocyte-specific morphology.

Origin of strong white electroluminescence from dense Si nanodots embedded in silicon nitride

Strong white electroluminescence (EL) from SiN-based devices containing Si nanodots with a density of more than 4.6×10(12)cm(2) was investigated. The white EL illustrates enhanced light emission with increasing applied voltage and can be divided into two components, a dominant peak at ~710 nm and weak one at ~550 nm, which are close to those of the PL spectra optically pumped by the 325 and 488 nm lines, respectively. Based on the PL characteristics, we propose that the dominant EL band arises from the band-to-band recombination in the dense Si nanodots where quantum confinement plays a decisive role in the light emission, whereas the weak EL band originates from the radiative Si dangling bond (K⁰) centers in the silicon nitride matrix.

Tea and cognitive health in late life: current evidence and future directions

This review summarizes the literature on the association between tea consumption and cognitive health in late life. Population-based studies reviewed in this article suggest that tea drinking has beneficial effects on cognitive function of elderly persons. However, a cause-effect relationship between tea consumption and cognitive decline and dementia could not be drawn given inconsistent findings from only two longitudinal cohort studies. The neuroprotective effects of tea consumption could be due to catechins, L-theanine and other compounds in tea leaves. More longitudinal observational study is needed. Information on life-time tea consumption and blood concentrations of catechins and L-theanine could be collected in future studies.

Effect of donor cell type on nuclear remodelling in rabbit somatic cell nuclear transfer embryos

Cloned rabbits have been produced for many years by somatic cell nuclear transfer (SCNT). The efficiency of cloning by SCNT, however, has remained extremely low. Most cloned embryos degenerate in utero, and the few that develop to term show a high incidence of post-natal death and abnormalities. The cell type used for donor nuclei is an important factor in nuclear transfer (NT). As reported previously, NT embryos reconstructed with fresh cumulus cells (CC-embryos) have better developmental potential than those reconstructed with foetal fibroblasts (FF-embryos) in vivo and in vitro. The reason for this disparity in developmental capacity is still unknown. In this study, we compared active demethylation levels and morphological changes between the nuclei of CC-embryos and FF-embryos shortly after activation. Anti-5-methylcytosine immunofluorescence of in vivo-fertilized and cloned rabbit embryos revealed that there was no detectable active demethylation in rabbit zygotes or NT-embryos derived from either fibroblasts or CC. In the process of nuclear remodelling, however, the proportion of nuclei with abnormal appearance in FF-embryos was significantly higher than that in CC-embryos during the first cell cycle. Our study demonstrates that the nuclear remodelling abnormality of cloned rabbit embryos may be one important factor for the disparity in developmental success between CC-embryos and FF-embryos.