Exploring Dark Energy with Next-Generation Photometric Redshift Surveys

The coming decade will be an exciting period for dark energy research, during which astronomers will address the question of what drives the accelerated cosmic expansion as first revealed by type Ia supernova (SN) distances, and confirmed by later observations. The mystery of dark energy poses a challenge of such magnitude that, as stated by the Dark Energy Task Force (DETF), nothing short of a revolution in our understanding of fundamental physics will be required to achieve a full understanding of the cosmic acceleration. The lack of multiple complementary precision observations is a major obstacle in developing lines of attack for dark energy theory. This lack is precisely what next-generation surveys will address via the powerful techniques of weak lensing (WL) and baryon acoustic oscillations (BAO) -- galaxy correlations more generally -- in addition to SNe, cluster counts, and other probes of geometry and growth of structure. Because of their unprecedented statistical power, these surveys demand an accurate understanding of the observables and tight control of systematics. This white paper highlights the opportunities, approaches, prospects, and challenges relevant to dark energy studies with wide-deep multiwavelength photometric redshift surveys. Quantitative predictions are presented for a 20000 sq. deg. ground-based 6-band (ugrizy) survey with 5-sigma depth of r~27.5, i.e., a Stage 4 survey as defined by the DETF

Superconducting properties in heavily overdoped Ba(Fe0.86Co0.14)2As2 single crystals

We report the intrinsic superconducting parameters in a heavily overdoped Ba(Fe1-xCox)(2)As-2 (x=0.14) single crystal and their influence in the resulting vortex dynamics. We find a bulk superconducting critical temperature of 9.8 K, magnetic penetration depth lambda(ab) (0)=660 +/- 50 nm, coherence length xi(ab) (0)=6.4 +/- 0.2 nm, and the upper critical field anisotropy gamma(T -> Tc) approximate to 3.7. The vortex phase diagram, in comparison with the optimally doped compound, presents a narrow collective creep regime. The intrinsic pinning energy plays an important role in the resulting vortex dynamics as compared with similar pinning landscape and comparable intrinsic thermal fluctuations. (C) 2014 Elsevier Ltd. All rights reserved.X1111Ysciescopu

Hubble Space Telescope Discovery of a z = 3.9 Multiply Imaged Galaxy Behind the Complex Cluster Lens WARPS J1415.1+36 at z = 1.026

We report the discovery of a multiply lensed Ly Alpha (Lya) emitter at z = 3.90 behind the massive galaxy cluster WARPS J1415.1+3612 at z = 1.026. Images taken by the Hubble Space Telescope(HST) using ACS reveal a complex lensing system that produces a prominent, highly magnified arc and a triplet of smaller arcs grouped tightly around a spectroscopically confirmed cluster member. Spectroscopic observations using FOCAS on Subaru confirm strong Lya emission in the source galaxy and provide redshifts for more than 21 cluster members, from which we obtain a velocity dispersion of 807+/-185 km/s. Assuming a singular isothermal sphere profile, the mass within the Einstein ring (7.13+/-0.38 ) corresponds to a central velocity dispersion of 686+15-19 km/s for the cluster, consistent with the value estimated from cluster member redshifts. Our mass profile estimate from combining strong lensing and dynamical analyses is in good agreement with both X-ray and weak lensing results

The critical role of ERK in death resistance and invasiveness of hypoxia-selected glioblastoma cells

<p>Abstract</p> <p>Background</p> <p>The rapid growth of tumor parenchyma leads to chronic hypoxia that can result in the selection of cancer cells with a more aggressive behavior and death-resistant potential to survive and proliferate. Thus, identifying the key molecules and molecular mechanisms responsible for the phenotypic changes associated with chronic hypoxia has valuable implications for the development of a therapeutic modality. The aim of this study was to identify the molecular basis of the phenotypic changes triggered by chronic repeated hypoxia.</p> <p>Methods</p> <p>Hypoxia-resistant T98G (HRT98G) cells were selected by repeated exposure to hypoxia and reoxygenation. Cell death rate was determined by the trypan blue exclusion method and protein expression levels were examined by western blot analysis. The invasive phenotype of the tumor cells was determined by the Matrigel invasion assay. Immunohistochemistry was performed to analyze the expression of proteins in the brain tumor samples. The Student T-test and Pearson Chi-Square test was used for statistical analyses.</p> <p>Results</p> <p>We demonstrate that chronic repeated hypoxic exposures cause T98G cells to survive low oxygen tension. As compared with parent cells, hypoxia-selected T98G cells not only express higher levels of anti-apoptotic proteins such as Bcl-2, Bcl-X_L, and phosphorylated ERK, but they also have a more invasive potential in Matrigel invasion chambers. Activation or suppression of ERK pathways with a specific activator or inhibitor, respectively, indicates that ERK is a key molecule responsible for death resistance under hypoxic conditions and a more invasive phenotype. Finally, we show that the activation of ERK is more prominent in malignant glioblastomas exposed to hypoxia than in low grade astrocytic glial tumors.</p> <p>Conclusion</p> <p>Our study suggests that activation of ERK plays a pivotal role in death resistance under chronic hypoxia and phenotypic changes related to the invasive phenotype of HRT98G cells compared to parent cells.</p

Functional Remineralization of Dentin Lesions Using Polymer-Induced Liquid-Precursor Process

It was hypothesized that applying the polymer-induced liquid-precursor (PILP) system to artificial lesions would result in time-dependent functional remineralization of carious dentin lesions that restores the mechanical properties of demineralized dentin matrix. 140 µm deep artificial caries lesions were remineralized via the PILP process for 7–28 days at 37°C to determine temporal remineralization characteristics. Poly-L-aspartic acid (27 KDa) was used as the polymeric process-directing agent and was added to the remineralization solution at a calcium-to-phosphate ratio of 2.14 (mol/mol). Nanomechanical properties of hydrated artificial lesions had a low reduced elastic modulus (ER = 0.2 GPa) region extending about 70 μm into the lesion, with a sloped region to about 140 μm where values reached normal dentin (18–20 GPa). After 7 days specimens recovered mechanical properties in the sloped region by 51% compared to the artificial lesion. Between 7–14 days, recovery of the outer portion of the lesion continued to a level of about 10 GPa with 74% improvement. 28 days of PILP mineralization resulted in 91% improvement of ER compared to the artificial lesion. These differences were statistically significant as determined from change-point diagrams. Mineral profiles determined by micro x-ray computed tomography were shallower than those determined by nanoindentation, and showed similar changes over time, but full mineral recovery occurred after 14 days in both the outer and sloped portions of the lesion. Scanning electron microscopy and energy dispersive x-ray analysis showed similar morphologies that were distinct from normal dentin with a clear line of demarcation between the outer and sloped portions of the lesion. Transmission electron microscopy and selected area electron diffraction showed that the starting lesions contained some residual mineral in the outer portions, which exhibited poor crystallinity. During remineralization, intrafibrillar mineral increased and crystallinity improved with intrafibrillar mineral exhibiting the orientation found in normal dentin or bone

The Ubiquitin Ligase Ubr2, a Recognition E3 Component of the N-End Rule Pathway, Stabilizes Tex19.1 during Spermatogenesis

Ubiquitin E3 ligases target their substrates for ubiquitination, leading to proteasome-mediated degradation or altered biochemical properties. The ubiquitin ligase Ubr2, a recognition E3 component of the N-end rule proteolytic pathway, recognizes proteins with N-terminal destabilizing residues and plays an important role in spermatogenesis. Tex19.1 (also known as Tex19) has been previously identified as a germ cell-specific protein in mouse testis. Here we report that Tex19.1 forms a stable protein complex with Ubr2 in mouse testes. The binding of Tex19.1 to Ubr2 is independent of the second position cysteine of Tex19.1, a putative target for arginylation by the N-end rule pathway R-transferase. The Tex19.1-null mouse mutant phenocopies the Ubr2-deficient mutant in three aspects: heterogeneity of spermatogenic defects, meiotic chromosomal asynapsis, and embryonic lethality preferentially affecting females. In Ubr2-deficient germ cells, Tex19.1 is transcribed, but Tex19.1 protein is absent. Our results suggest that the binding of Ubr2 to Tex19.1 metabolically stabilizes Tex19.1 during spermatogenesis, revealing a new function for Ubr2 outside the conventional N-end rule pathway

Cluster Lenses

Clusters of galaxies are the most recently assembled, massive, bound structures in the Universe. As predicted by General Relativity, given their masses, clusters strongly deform space-time in their vicinity. Clusters act as some of the most powerful gravitational lenses in the Universe. Light rays traversing through clusters from distant sources are hence deflected, and the resulting images of these distant objects therefore appear distorted and magnified. Lensing by clusters occurs in two regimes, each with unique observational signatures. The strong lensing regime is characterized by effects readily seen by eye, namely, the production of giant arcs, multiple-images, and arclets. The weak lensing regime is characterized by small deformations in the shapes of background galaxies only detectable statistically. Cluster lenses have been exploited successfully to address several important current questions in cosmology: (i) the study of the lens(es) - understanding cluster mass distributions and issues pertaining to cluster formation and evolution, as well as constraining the nature of dark matter; (ii) the study of the lensed objects - probing the properties of the background lensed galaxy population - which is statistically at higher redshifts and of lower intrinsic luminosity thus enabling the probing of galaxy formation at the earliest times right up to the Dark Ages; and (iii) the study of the geometry of the Universe - as the strength of lensing depends on the ratios of angular diameter distances between the lens, source and observer, lens deflections are sensitive to the value of cosmological parameters and offer a powerful geometric tool to probe Dark Energy. In this review, we present the basics of cluster lensing and provide a current status report of the field.Comment: About 120 pages - Published in Open Access at: http://www.springerlink.com/content/j183018170485723/ . arXiv admin note: text overlap with arXiv:astro-ph/0504478 and arXiv:1003.3674 by other author

Ell3 Enhances Differentiation of Mouse Embryonic Stem Cells by Regulating Epithelial-Mesenchymal Transition and Apoptosis

Ell3 is a testis-specific RNA polymerase II elongation factor whose cellular function is not clear. The present study shows that Ell3 is activated during the differentiation of mouse embryonic stem cells (mESCs). Furthermore, Ell3 plays a critical role in stimulating lineage differentiation of mESCs by promoting epithelial-mesenchymal transition (EMT) and suppressing apoptosis. Mouse ESCs engineered to stably express Ell3 were rapidly differentiated compared with control cells either under spontaneous differentiation or neural lineage-specific differentiation conditions. Gene expression profile and quantitative RT-PCR analysis showed that the expression of EMT markers, such as Zeb1 and Zeb2, two major genes that regulate EMT, was upregulated in Ell3-overexpressing mESCs. Remarkably, knockdown of Zeb1 attenuated the enhanced differentiation capacity of Ell3-overexpressing mESCs, which indicates that Ell3 plays a role in the induction of mESC differentiation by inducing EMT. In contrast to Ell3-overexpressing mESCs, Ell3-knock down mESCs could not differentiate under differentiation conditions and, instead, underwent caspase-dependent apoptosis. In addition, apoptosis of differentiating Ell3-knock out mESCs was associated with enhanced expression of p53. The present results suggest that Ell3 promotes the differentiation of mESCs by activating the expression of EMT-related genes and by suppressing p53 expression

The effect of acute vs chronic magnesium supplementation on exercise and recovery on resistance exercise, blood pressure and total peripheral resistance on normotensive adults

© 2015 Kass and Poeira; licensee BioMed Central. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Background: Magnesium supplementation has previously shown reductions in blood pressure of up to 12 mmHg. A positive relationship between magnesium supplementation and performance gains in resistance exercise has also been seen. However, no previous studies have investigated loading strategies to optimise response. The aim of this study was to assess the effect of oral magnesium supplementation on resistance exercise and vascular response after intense exercise for an acute and chronic loading strategy on a 2-day repeat protocol. Methods: The study was a randomised, double-blind, cross-over design, placebo controlled 2 day repeat measure protocol (n = 13). Intense exercise (40 km time trial) was followed by bench press at 80% 1RM to exhaustion, with blood pressure and total peripheral resistance (TPR) recorded. 300 mg/d elemental magnesium was supplemented for either a 1 (A) or 4 (Chr) week loading strategy. Food diaries were recorded. Results: Dietary magnesium intake was above the Reference Nutrient Intake (RNI) for all groups. Bench press showed a significant increase of 17.7% (p = 0.031) for A on day 1. On day 2 A showed no decrease in performance whilst Chr showed a 32.1% decrease. On day 2 post-exercise systolic blood pressure (SBP) was significantly lower in both A (p = 0.0.47) and Chr (p = 0.016) groups. Diastolic blood pressure (DBP) showed significant decreases on day 2 solely for A (p = 0.047) with no changes in the Chr. TPR reduced for A on days 1 and 2 (p = 0.031) with Chr showing an increase on day 1 (p = 0.008) and no change on day 2. Conclusion: There was no cumulative effect of Chr supplementation compared to A. A group showed improvement for bench press concurring with previous research which was not seen in Chr. On day 2 A showed a small non-significant increase but not a decrement as expected with Chr showing a decrease. DBP showed reductions in both Chr and A loading, agreeing with previous literature. This is suggestive of a different mechanism for BP reduction than for muscular strength. TPR showed greater reductions with A than Chr, which would not be expected as both interventions had reductions in BP, which is associated with TPR.Peer reviewedFinal Published versio

Association between a variation in the phosphodiesterase 4D gene and bone mineral density

BACKGROUND: Fragility fractures caused by osteoporosis are a major cause of morbidity and mortality in aging populations. Bone mineral density (BMD) is a useful surrogate marker for risk of fracture and is a highly heritable trait. The genetic variants underlying this genetic contribution are largely unknown. METHODS: We performed a large-scale association study investigating more than 25,000 single nucleotide polymorphisms (SNPs) located within 16,000 genes. Allele frequencies were estimated in contrasting DNA pools from white females selected for low (<0.87 g/cm(2), n = 319) and high (> 1.11 g/cm(2), n = 321) BMD at the lumbar spine. Significant findings were verified in two additional sample collections. RESULTS: Based on allele frequency differences between DNA pools and subsequent individual genotyping, one of the candidate loci indicated was the phosphodiesterase 4D (PDE4D) gene region on chromosome 5q12. We subsequently tested the marker SNP, rs1498608, in a second sample of 138 white females with low (<0.91 g/cm(2)) and 138 females with high (>1.04 g/cm(2)) lumbar spine BMD. Odds ratios were 1.5 (P = 0.035) in the original sample and 2.1 (P = 0.018) in the replication sample. Association fine mapping with 80 SNPs located within 50 kilobases of the marker SNP identified a 20 kilobase region of association containing exon 6 of PDE4D. In a second, family-based replication sample with a preponderance of females with low BMD, rs1498608 showed an opposite relationship with BMD at different sites (p = 0.00044-0.09). We also replicated the previously reported association of the Ser37Ala polymorphism in BMP2, known to interact biologically with PDE4D, with BMD. CONCLUSION: This study indicates that variants in the gene encoding PDE4D account for some of the genetic contribution to bone mineral density variation in humans. The contrasting results from different samples indicate that the effect may be context-dependent. PDE4 inhibitors have been shown to increase bone mass in normal and osteopenic mice, but up until now there have been no reports implicating any member of the PDE4 gene family in human osteoporosis