(2 +1)-dimensional Duffin-Kemmer-Petiau oscillator under a magnetic field in the presence of a minimal length in the noncommutative space

Using the momentum space representation, we study the (2 +1)-dimensional Duffin-Kemmer-Petiau oscillator for spin 0 particle under a magnetic field in the presence of a minimal length in the noncommutative space. The explicit form of energy eigenvalues are found, the wave functions and the corresponding probability density are reported in terms of the Jacobi polynomials. Additionally, we also discuss the special cases and depict the corresponding numerical results

Heptacarbonyldiosmium and Hexacarbonyldiosmium: Two Highly Unsaturated Binuclear Osmium Carbonyls

A total of nine singlet structures for Os2(CO)7 and 15 structures (nine singlet and six triplet) for Os2(CO)6 have been found by density functional theory thereby indicating very complicated energy surfaces. The global minimum for Os2(CO)7 is a doubly carbonyl bridged structure Os2(CO)5(μ-CO)2 with an Os=Os distance of 2.67 Å suggesting a formal double bond and hence a 16-electron rather than an 18-electron configuration for one of the osmium atoms. However, at only slightly higher energy (3.2 kcal mol−1) lies an unbridged Os2(CO)7 structure with a shorter Os≡Os distance of 2.54 Å, corresponding to a formal triple bond and an 18-electron configuration for each osmium atom. The global minimum for Os2(CO)6 can be derived from that of Os2(CO)7 by removal of a carbonyl group while retaining the Os=Os double bond and the two bridging carbonyl groups. Slightly higher energy Os2(CO)6 structures at ≈3 kcal mol−1 or more above the global minimum have short Os-Os quadrupole bond distances around 2.4 Å, consistent with the formal quadruple bonds necessary to give both osmium atoms the favored 18-electron configuration. None of the 24 structures for Os2(CO)7 and Os2(CO)6 found in this work has a four-electron donor η2-μ-CO bridging carbonyl group

CHIP-mediated stress recovery by sequential ubiquitination of substrates and Hsp70

Exposure of cells to various stresses often leads to the induction of a group of proteins called heat shock proteins (HSPs, molecular chaperones)1,2. Hsp70 is one of the most highly inducible molecular chaperones, but its expression must be maintained at low levels under physiological conditions to permit constitutive cellular activities to proceed3,4. Heat shock transcription factor 1 (HSF1) is the transcriptional regulator of HSP gene expression5, but it remains poorly understood how newly synthesized HSPs return to basal levels when HSF1 activity is attenuated. CHIP (carboxy terminus of Hsp70-binding protein), a dual-function co-chaperone/ubiquitin ligase, targets a broad range of chaperone substrates for proteasomal degradation6–11. Here we show that CHIP not only enhances Hsp70 induction during acute stress but also mediates its turnover during the stress recovery process. Central to this dual-phase regulation is its substrate dependence: CHIP preferentially ubiquitinates chaperone-bound substrates, whereas degradation of Hsp70 by CHIP-dependent targeting to the ubiquitin–proteasome system occurs when misfolded substrates have been depleted. The sequential catalysis of the CHIP-associated chaperone adaptor and its bound substrate provides an elegant mechanism for maintaining homeostasis by tuning chaperone levels appropriately to reflect the status of protein folding within the cytoplasm

Trends in survival of ovarian clear cell carcinoma patients from 2000 to 2015

PurposeTo analyze changes in survival outcomes in patients with ovarian clear cell carcinoma (OCCC) treated consecutively over a 16-year period using a population-based cohort.MethodsWe conducted a retrospective analysis of OCCC from 2000 to 2015 using data from the Surveillance, Epidemiology, and End Results (SEER) program. The ovarian cancer-specific survival (OCSS) and overall survival (OS) were analyzed according to the year of diagnosis. Joinpoint Regression Program, Kaplan-Meier analysis, and multivariate Cox regression analyses were used for statistical analysis.ResultsWe included 4257 patients in the analysis. The analysis of annual percentage change in OCSS (P=0.014) and OS (P=0.006) showed that patients diagnosed in later years had significantly better outcomes compared to those diagnosed in early years. The results of the multivariate Cox regression analyses showed that the year of diagnosis was the independent prognostic factor associated with OCSS (P=0.004) and had a borderline effect on OS (P=0.060). Regarding the SEER staging, the OCSS (P=0.017) and OS (P=0.004) of patients with distant stage showed a significant trend toward increased, while no significant trends were found in the survival of patients with localized or regional stage diseases. Similar trends were found in those aged <65 years or those treated with surgery and chemotherapy. However, no statistically significant changes in the survival rate were found in those aged ≥65 years or those receiving surgery alone regardless of SEER stage during the study period.ConclusionsOur study observed a significant increase in the survival outcomes in OCCC from 2000 to 2015, and patients aged <65 years and those with distant stage experienced a greater improvement in survival

The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7

We present the discovery of nine quasars at $z\sim6$ identified in the Sloan Digital Sky Survey (SDSS) imaging data. This completes our survey of $z\sim6$ quasars in the SDSS footprint. Our final sample consists of 52 quasars at $5.7<z\le6.4$, including 29 quasars with $z_{\rm AB}\le20$ mag selected from 11,240 deg$^2$ of the SDSS single-epoch imaging survey (the main survey), 10 quasars with $20\le z_{\rm AB}\le20.5$ selected from 4223 deg$^2$ of the SDSS overlap regions (regions with two or more imaging scans), and 13 quasars down to $z_{\rm AB}\approx22$ mag from the 277 deg$^2$ in Stripe 82. They span a wide luminosity range of $-29.0\le M_{1450}\le-24.5$. This well-defined sample is used to derive the quasar luminosity function (QLF) at $z\sim6$. After combining our SDSS sample with two faint ($M_{1450}\ge-23$ mag) quasars from the literature, we obtain the parameters for a double power-law fit to the QLF. The bright-end slope $\beta$ of the QLF is well constrained to be $\beta=-2.8\pm0.2$. Due to the small number of low-luminosity quasars, the faint-end slope $\alpha$ and the characteristic magnitude $M_{1450}^{\ast}$ are less well constrained, with $\alpha=-1.90_{-0.44}^{+0.58}$ and $M^{\ast}=-25.2_{-3.8}^{+1.2}$ mag. The spatial density of luminous quasars, parametrized as $\rho(M_{1450}<-26,z)=\rho(z=6)\,10^{k(z-6)}$, drops rapidly from $z\sim5$ to 6, with $k=-0.72\pm0.11$. Based on our fitted QLF and assuming an IGM clumping factor of $C=3$, we find that the observed quasar population cannot provide enough photons to ionize the $z\sim6$ IGM at $\sim90$\% confidence. Quasars may still provide a significant fraction of the required photons, although much larger samples of faint quasars are needed for more stringent constraints on the quasar contribution to reionization.Comment: 20 pages, 12 figures, Accepted for publication in The Astrophysical Journa

Discovery of six high-redshift quasars with the Lijiang 2.4m telescope and the Multiple Mirror Telescope

Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with $i$-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from the YFOSC spectroscopy of the Lijiang 2.4m telescope in February, 2012. These quasars are in the list of $z>3.6$ quasar candidates selected by using our proposed $J-K/i-Y$ criterion and the photometric redshift estimations from the SDSS optical and UKIDSS near-IR photometric data. Nine candidates were observed by YFOSC, and five among six new quasars were identified as $z>3.6$ quasars. One of the other three objects was identified as a star and the other two were unidentified due to the lower signal-to-noise ratio of their spectra. This is the first time that $z>4$ quasars have been discovered using a telescope in China. Thanks to the Chinese Telescope Access Program (TAP), the redshift of 4.6 for one of these quasars was confirmed by the Multiple Mirror Telescope (MMT) Red Channel spectroscopy. The continuum and emission line properties of these six quasars, as well as their central black hole masses and Eddington ratios, were obtained.Comment: 7 pages, 2 figures, published in Research in Astronomy and Astrophysics (RAA) as a lette

Regulation of the Cytoplasmic Quality Control Protein Degradation Pathway by BAG2

The cytoplasm is protected against the perils of protein misfolding by two mechanisms: molecular chaperones (which facilitate proper folding) and the ubiquitin-proteasome system, which regulates degradation of misfolded proteins. CHIP (carboxyl terminus of Hsp70-interacting protein) is an Hsp70-associated ubiquitin ligase that participates in this process by ubiquitylating misfolded proteins associated with cytoplasmic chaperones. Mechanisms that regulate the activity of CHIP are, at present, poorly understood. Using a proteomics approach, we have identified BAG2, a previously uncharacterized BAG domain-containing protein, as a common component of CHIP holocomplexes in vivo. Binding assays indicate that BAG2 associates with CHIP as part of a ternary complex with Hsc70, and BAG2 colocalizes with CHIP under both quiescent conditions and after heat shock. In vitro and in vivo ubiquitylation assays indicate that BAG2 is an efficient and specific inhibitor of CHIP-dependent ubiquitin ligase activity. This activity is due, in part, to inhibition of interactions between CHIP and its cognate ubiquitin-conjugating enzyme, UbcH5a, which may in turn be facilitated by ATP-dependent remodeling of the BAG2-Hsc70-CHIP heterocomplex. The association of BAG2 with CHIP provides a cochaperone-dependent regulatory mechanism for preventing unregulated ubiquitylation of misfolded proteins by CHIP

Hard X-ray nano-focusing with Montel mirror optics

a b s t r a c t Kirkpatrick-Baez mirrors in the Montel (or nested) configuration were tested for hard X-ray nanoscale focusing at a third generation synchrotron beamline. In this scheme, two mirrors, mounted side-by-side and perpendicular to each other, provide for a more compact focusing system and a much higher demagnification and flux than the traditional sequential K-B mirror arrangement. They can accept up to a 120 mm  120 mm incident X-ray beam with a long working distance of 40 mm and broad-bandpass of energies up to $ 30 keV. Initial test demonstrated a focal spot of about 150 nm in both horizontal and vertical directions with either polychromatic or monochromatic beam. Montel mirror optics is important and very appealing for achromatic X-ray nanoscale focusing in conventional non-extra-long synchrotron beamlines