1,890 research outputs found
The Angular Clustering of Galaxy Pairs
We identify close pairs of galaxies from 278 deg^2 of Sloan Digital Sky
Survey commissioning imaging data. The pairs are drawn from a sample of 330,041
galaxies with 18 < r^* < 20. We determine the angular correlation function of
galaxy pairs, and find it to be stronger than the correlation function of
single galaxies by a factor of 2.9 +/- 0.4. The two correlation functions have
the same logarithmic slope of 0.77. We invert Limber's equation to estimate the
three-dimensional correlation functions; we find clustering lengths of r_0= 4.2
+/- 0.4 h^{-1} Mpc for galaxies and 7.8 +/- 0.7 h^{-1} Mpc for galaxy pairs.
These results agree well with the global richness dependence of the correlation
functions of galaxy systems.Comment: 12 pages. ApJ, in pres
Electrospun nanosized cellulose fibers using ionic liquids at room temperature
Aiming at replacing the noxious solvents commonly employed, ionic-liquid-based solvents have been recently explored as novel non-volatile and non-flammable media for the electrospinning of polymers. In this work, nanosized and biodegradable cellulose fibers were obtained by electrospinning at room temperature using a pure ionic liquid or a binary mixture of two selected ionic liquids. The electrospinning of 8 wt% cellulose in 1-ethyl-3-methylimidazolium acetate medium (a low viscosity and room temperature ionic liquid capable of efficiently dissolving cellulose) showed to produce electrospun fibers with average diameters within (470 ± 110) nm. With the goal of tailoring the surface tension of the spinning dope, a surface active ionic liquid was further added in a 0.10 : 0.90 mole fraction ratio. Electrospun cellulose fibers from the binary mixture composed of 1-ethyl-3-methylimidazolium acetate and 1-decyl-3-methylimidazolium chloride ionic liquids presented average diameters within (120 ± 55) nm. Scanning electron microscopy, X-ray diffraction analysis, nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric assays were used as core methods to evaluate the structural integrity, morphology and crystallinity of the raw, electrospun, and regenerated samples of cellulose. Moreover, the photoluminescence spectra of both raw and electrospun fibers were acquired, and compared, indicating that the cellulose emitting centers are not affected by the dissolution of cellulose in ionic liquids. Finally, the use of non-volatile solvents in electrospinning coupled to a water coagulation bath allows the recovery of the ionic fluid, and represents a step forward into the search of environmentally friendly alternatives to the conventional approaches
Essential and checkpoint functions of budding yeast ATM and ATR during meiotic prophase are facilitated by differential phosphorylation of a meiotic adaptor protein, Hop1
A hallmark of the conserved ATM/ATR signalling is its ability to mediate a wide range of functions utilizing only a limited number of adaptors and effector kinases. During meiosis, Tel1 and Mec1, the budding yeast ATM and ATR, respectively, rely on a meiotic adaptor protein Hop1, a 53BP1/Rad9 functional analog, and its associated kinase Mek1, a CHK2/Rad53-paralog, to mediate multiple functions: control of the formation and repair of programmed meiotic DNA double strand breaks, enforcement of inter-homolog bias, regulation of meiotic progression, and implementation of checkpoint responses. Here, we present evidence that the multi-functionality of the Tel1/Mec1-to-Hop1/Mek1 signalling depends on stepwise activation of Mek1 that is mediated by Tel1/Mec1 phosphorylation of two specific residues within Hop1: phosphorylation at the threonine 318 (T318) ensures the transient basal level Mek1 activation required for viable spore formation during unperturbed meiosis. Phosphorylation at the serine 298 (S298) promotes stable Hop1-Mek1 interaction on chromosomes following the initial phospho-T318 mediated Mek1 recruitment. In the absence of Dmc1, the phospho-S298 also promotes Mek1 hyper-activation necessary for implementing meiotic checkpoint arrest. Taking these observations together, we propose that the Hop1 phospho-T318 and phospho-S298 constitute key components of the Tel1/Mec1- based meiotic recombination surveillance (MRS) network and facilitate effective coupling of meiotic recombination and progression during both unperturbed and challenged meiosis
The Angular Correlation Function of Galaxies from Early SDSS Data
The Sloan Digital Sky Survey is one of the first multicolor photometric and
spectroscopic surveys designed to measure the statistical properties of
galaxies within the local Universe. In this Letter we present some of the
initial results on the angular 2-point correlation function measured from the
early SDSS galaxy data. The form of the correlation function, over the
magnitude interval 18<r*<22, is shown to be consistent with results from
existing wide-field, photographic-based surveys and narrower CCD galaxy
surveys. On scales between 1 arcminute and 1 degree the correlation function is
well described by a power-law with an exponent of ~ -0.7. The amplitude of the
correlation function, within this angular interval, decreases with fainter
magnitudes in good agreement with analyses from existing galaxy surveys. There
is a characteristic break in the correlation function on scales of
approximately 1-2 degrees. On small scales, < 1', the SDSS correlation function
does not appear to be consistent with the power-law form fitted to the 1'<
theta <0.5 deg data. With a data set that is less than 2% of the full SDSS
survey area, we have obtained high precision measurements of the power-law
angular correlation function on angular scales 1' < theta < 1 deg, which are
robust to systematic uncertainties. Because of the limited area and the highly
correlated nature of the error covariance matrix, these initial results do not
yet provide a definitive characterization of departures from the power-law form
at smaller and larger angles. In the near future, however, the area of the SDSS
imaging survey will be sufficient to allow detailed analysis of the small and
large scale regimes, measurements of higher-order correlations, and studies of
angular clustering as a function of redshift and galaxy type
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A Comprehensive Resource for Induced Pluripotent Stem Cells from Patients with Primary Tauopathies.
Primary tauopathies are characterized neuropathologically by inclusions containing abnormal forms of the microtubule-associated protein tau (MAPT) and clinically by diverse neuropsychiatric, cognitive, and motor impairments. Autosomal dominant mutations in the MAPT gene cause heterogeneous forms of frontotemporal lobar degeneration with tauopathy (FTLD-Tau). Common and rare variants in the MAPT gene increase the risk for sporadic FTLD-Tau, including progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). We generated a collection of fibroblasts from 140 MAPT mutation/risk variant carriers, PSP, CBD, and cognitively normal controls; 31 induced pluripotent stem cell (iPSC) lines from MAPT mutation carriers, non-carrier family members, and autopsy-confirmed PSP patients; 33 genome engineered iPSCs that were corrected or mutagenized; and forebrain neural progenitor cells (NPCs). Here, we present a resource of fibroblasts, iPSCs, and NPCs with comprehensive clinical histories that can be accessed by the scientific community for disease modeling and development of novel therapeutics for tauopathies
Multiple Cancer/Testis Antigens Are Preferentially Expressed in Hormone-Receptor Negative and High-Grade Breast Cancers
BACKGROUND: Cancer/testis (CT) antigens are protein antigens normally expressed only in germ cells of testis, and yet are expressed in a proportion of a wide variety of human cancers. CT antigens can elicit spontaneous immune responses in cancer patients with CT-positive cancers, and CT antigen-based therapeutic cancer vaccine trials are ongoing for "CT-rich" tumors. Although some previous studies found breast cancer to be "CT-poor", our recent analysis identified increased CT mRNA transcripts in the ER-negative subset of breast cancer. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we performed a comprehensive immunohistochemical study to investigate the protein expression of eight CT genes in 454 invasive ductal carcinomas, including 225 ER/PR/HER2-negative (triple-negative) carcinomas. We found significantly more frequent expression of all eight CT antigens in ER-negative cancers, and five of them--MAGEA, CT7, NY-ESO-1, CT10 and CT45, were expressed in 12-24% of ER-negative cancers, versus 2-6% of ER-positive cancers (p<0.001 to 0.003). In comparison, GAGE, SAGE1 and NXF2 were only expressed in 3-5% of ER-negative and 0-2% of ER-positive cancers. ER-negative cancers were also more likely to simultaneously co-express multiple CT antigens, with 27% (34/125) of ER-negative, CT-positive tumors expressing three or more CT antigens. HER2 status had no consistent effect on CT expression, and triple-negative carcinomas showed similar frequencies of MAGEA and NY-ESO-1 expression as ER-negative/HER2-positive carcinomas. More frequent CT expression was also found in tumors with higher nuclear grade (p<0.001 to p = 0.01) and larger in size (>2 cm). CONCLUSIONS/SIGNIFICANCE: CT antigens are preferentially expressed in hormone receptor-negative and high-grade breast cancer. Considering the limited treatment options for ER/PR/HER2 triple-negative breast cancer, the potential of CT-based immunotherapy should be explored
Effects of dose modifications on the safety and efficacy of dacomitinib for EGFR mutation-positive non-small-cell lung cancer
Aim: We evaluated reasons for dacomitinib dose reduction (DR) and examined adverse event (AE) incidence, key efficacy end points (progression-free survival [PFS]/overall survival [OS]), and pharmacokinetics in dose-reducing patients in the ARCHER 1050 trial. Patients & methods: Newly diagnosed patients with EGFR mutation-positive, advanced non-small-cell lung cancer received oral dacomitinib (45 mg once-daily [QD]), with stepwise toxicity-managing DR (30 and 15 mg QD) permitted. Results: Skin toxicities (62.7%) were the most common DR-leading AEs. The AE incidence and severity decreased following DRs. Initial plasma dacomitinib exposure (45 mg QD) was generally lower in patients remaining at 45 mg QD compared with dose-reducing patients. Median PFS and OS were similar in all dacomitinib-treated patients and dose-reducing patients. Conclusion: Tolerability-guided dose modifications enabled patients to continue with dacomitinib and benefit from PFS/OS improvement
Ampullary cancers harbor ELF3 tumor suppressor gene mutations and exhibit frequent WNT dysregulation
The ampulla of Vater is a complex cellular environment from which adenocarcinomas arise to form a group of histopathologically heterogenous tumors. To evaluate the molecular features of these tumors, 98 ampullary adenocarcinomas were evaluated and compared to 44 distal bile duct and 18 duodenal adenocarcinomas. Genomic analyses revealed mutations in the WNT signaling pathway among half of the patients and in all three adenocarcinomas irrespective of their origin and histological morphology. These tumors were characterized by a high frequency of inactivating mutations of ELF3, a high rate of microsatellite instability, and common focal deletions and amplifications, suggesting common attributes in the molecular pathogenesis are at play in these tumors. The high frequency of WNT pathway activating mutation, coupled with small-molecule inhibitors of β-catenin in clinical trials, suggests future treatment decisions for these patients may be guided by genomic analysis
Associations of common breast cancer susceptibility alleles with risk of breast cancer subtypes in BRCA1 and BRCA2 mutation carriers
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