Measurement of the Top Pair Production Cross Section in the Dilepton Decay Channel in ppbar Collisions at sqrt s = 1.96 TeV

Submitted to Phys. Rev. DA measurement of the \ttbar production cross section in \ppbar collisions at $\sqrt{{\rm s}}$ = 1.96 TeV using events with two leptons, missing transverse energy, and jets is reported. The data were collected with the CDF II Detector. The result in a data sample corresponding to an integrated luminosity 2.8 fb$^{-1}$ is: \sigma_{\ttbar} = 6.27 $\pm$ 0.73(stat) $\pm$ 0.63(syst) $\pm$ 0.39(lum) pb. for an assumed top mass of 175 GeV/$c^{2}$.A measurement of the tt̅ production cross section in pp̅ collisions at √s=1.96  TeV using events with two leptons, missing transverse energy, and jets is reported. The data were collected with the CDF II detector. The result in a data sample corresponding to an integrated luminosity 2.8  fb-1 is σtt̅ =6.27±0.73(stat)±0.63(syst)±0.39(lum)  pb. for an assumed top mass of 175  GeV/c2.Peer reviewe

Tracking Structural Changes of Carbon Nanotube Electrodes for Lithium–Air Batteries by Time-Resolved <i>Operando</i> Wide- and Small-Angle X‑ray Scattering

In this study, we prepared single-walled carbon nanotube electrodes for lithium–air batteries (LABs) to investigate the structural changes of the electrodes during the discharge–charge cycle coupled with the precipitation and decomposition of Li oxide. Wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS) were used for the structural analysis. A new test cell was designed and fabricated to perform these measurements under operando conditions. From the results of the WAXS measurements during discharge tests, diffraction peaks indicating crystalline oxides and a broad peak indicating amorphous components were observed. The intensities of these peaks increased rapidly in the later stages of the discharge. Moreover, the WAXS measurements showed that the peak of the amorphous component preferentially disappears during the charging process. Furthermore, the nanoscale structural changes associated with the precipitation and decomposition of Li oxide were analyzed using SAXS. The results suggest that the electrode expansion caused electrolyte depletion in the electrode. The post-test electrode thickness was also analyzed, and the results support interpreting the data obtained from WAXS and SAXS. We think that the structural analysis approach and the pore formation discovered in this study will enable LABs to be used more effectively in the future

Preferential Positionings of Dopants and Co-dopants in Embedded and Freestanding Silicon Nanocrystals

In this work we aim at understanding the effect of n- and p-type substitutional doping in the case of matrix-embedded and freestanding Si nanocrystals. By means of ab initio calculations we identify the preferential positioning of the dopants and its effect on the structural properties with respect to the undoped case. Subsequently, we consider the case of phosphorus and boron co-doped nanocrystals showing that, against the single-doping situation, the energetics strongly favors the binding of the impurities at the nanocrystal surface. Indeed we demonstrate that the polar B-P bond forms a stable permanent electric dipole that radially points inward in the nanocrystal. Such a noteworthy characteristic and its physical consequences are discussed alongside new potential applications. \ua9 2014 American Chemical Society

Effectiveness of primary series, first, and second booster vaccination of monovalent mRNA COVID-19 vaccines against symptomatic SARS-CoV-2 infections and severe diseases during the SARS-CoV-2 omicron BA.5 epidemic in Japan: vaccine effectiveness real-time surveillance for SARS-CoV-2 (VERSUS)

This study aimed to evaluate VE of primary, first, and second booster ancestral-strain monovalent mRNA COVID-19 vaccination against symptomatic infections and severe diseases in Japan. We conducted a test-negative case-control study. We included medically attended episodes and hospitalizations involving individuals aged ≥16 with signs and symptoms from July to November 2022, when Omicron BA.5 was dominant nationwide. To evaluate VE, we calculated adjusted ORs of vaccination among test-positive versus test-negative individuals using a mixed-effects logistic regression. For VE against symptomatic infections among individuals aged 16 to 59, VE of primary vaccination at > 180 days was 26.1% (95% CI: 10.6–38.8%); VE of the first booster was 58.5% (48.4–66.7%) at ≤90 days, decreasing to 41.1% (29.5–50.8%) at 91 to 180 days. For individuals aged ≥60, VE of the first booster was 42.8% (1.7–66.7%) at ≤90 days, dropping to 15.4% (−25.9–43.2%) at 91 to 180 days, and then increasing to 44.0% (16.4–62.5%) after the second booster. For VE against severe diseases, VE of the first and second booster was 77.3% (61.2–86.7%) at ≤90 days and 55.9% (23.4–74.6%) afterward. mRNA booster vaccination provided moderate protection against symptomatic infections and high-level protection against severe diseases during the BA.5 epidemic in Japan.</p