2,758 research outputs found
New measurements of the cosmic infrared background fluctuations in deep Spitzer/IRAC survey data and their cosmological implications
We extend previous measurements of cosmic infrared background (CIB)
fluctuations to ~ 1 deg using new data from the Spitzer Extended Deep Survey.
Two fields, with depths of ~12 hr/pixel over 3 epochs, are analyzed at 3.6 and
4.5 mic. Maps of the fields were assembled using a self-calibration method
uniquely suitable for probing faint diffuse backgrounds. Resolved sources were
removed from the maps to a magnitude limit of AB mag ~ 25, as indicated by the
level of the remaining shot noise. The maps were then Fourier-transformed and
their power spectra were evaluated. Instrumental noise was estimated from the
time-differenced data, and subtracting this isolates the spatial fluctuations
of the actual sky. The power spectra of the source-subtracted fields remain
identical (within the observational uncertainties) for the three epochs
indicating that zodiacal light contributes negligibly to the fluctuations.
Comparing to 8 mic power spectra shows that Galactic cirrus cannot account for
the fluctuations. The signal appears isotropically distributed on the sky as
required for an extragalactic origin. The CIB fluctuations continue to diverge
to > 10 times those of known galaxy populations on angular scales out to < 1
deg. The low shot noise levels remaining in the diffuse maps indicate that the
large scale fluctuations arise from the spatial clustering of faint sources
well below the confusion noise. The spatial spectrum of these fluctuations is
in reasonable agreement with an origin in populations clustered according to
the standard cosmological model (LCDM) at epochs coinciding with the first
stars era.Comment: ApJ, to be publishe
Single-strand selective monofunctional uracil-DNA glycosylase (SMUG1) deficiency is linked to aggressive breast cancer and predicts response to adjuvant therapy
Uracil in DNA is an important cause of mutagenesis. SMUG1 is a uracil DNA glycosylase that removes uracil through base excision repair. SMUG1 also processes radiation induced oxidative base damage as well as 5-fluorouracil incorporated into DNA during chemotherapy. We investigated SMUG1 mRNA expression in 249 primary breast cancers. SMUG1 protein expression was investigated in 1165 breast tumours randomised into two cohorts [training set (n=583) and test set (n=582)]. SMUG1 and chemotherapy response was also investigated in a series of 315 ER negative tumours (n=315). For mechanistic insights, SMUG1 was correlated to biomarkers of aggressive phenotype, DNA repair, cell cycle and apoptosis. Low SMUG1 mRNA expression was associated with adverse disease specific survival (p=0.008) and disease free survival (p=0.008). Low SMUG1 protein expression (25%) was associated with high histological grade (p<0.0001), high mitotic index (p<0.0001), pleomorphism (p<0.0001), glandular de-differentiation (p=0.0001), absence of hormonal receptors (ER-/PgR-/AR) (p<0.0001), presence of basal-like (p<0.0001) and triple negative phenotypes (p<0.0001). Low SMUG1 protein expression was associated with loss of BRCA1 (p<0.0001), ATM (p<0.0001) and XRCC1 (p<0.0001). Low p27 (p<0.0001), low p21 (p=0.023), mutant p53 (p=0.037), low MDM2 (p<0.0001), low MDM4 (p=0.004), low Bcl-2 (p=0.001), low Bax (p=0.003) and high MIB1 (p<0.0001) were likely in low SMUG1 tumours. Low SMUG1 protein expression was associated with poor prognosis in univariate (p<0.001) and multivariate analysis (p<0.01). In ER+ cohort that received adjuvant endocrine therapy, low SMUG1 protein expression remains associated with poor survival (p<0.01). In ER- cohort that received adjuvant chemotherapy, low SMUG1 protein expression is associated with improved survival (p=0.043). Our study suggests that low SMUG1 expression may correlate to adverse clinicopathological features and predict response to adjuvant therapy in breast cancer
Regional climate modeling activities in relation to the CLAVIER project
Observational records show that the global climate is changing and these changes are visible in the Central and Eastern European Countries (CEEC). Certainly negative impacts of climate change will involve significant economic losses in several regions of Europe, while others may bring health or welfare problems somewhere else. Within the EU funded project CLAVIER (Climate ChAnge and Variability: Impact on Central and Eastern EURope) three representative CEEC are Studied in detail: Hungary, Romania, and Bulgaria. Researchers from 6 countries and different disciplines identify linkages between climate change and its impact on weather patterns with consequences oil air Pollution, extreme events, and water resources. Furthermore, an evaluation of the economic impact on agriculture, tourism, energy supply, and public sector will be conducted, CLAVIER focuses oil ongoing and future climate changes in CEEC using measurements and existing regional scenarios to determine possible developments of the climate and to address related uncertainties. Three regional climate models are used to simulate the climate evolution in CEEC for the period 1951 to 2050, the future regional climate projection being the first half of the 21st century. The issue of climate change uncertainties is addressed through the multi-model and multi-scenario ensemble approach. As a result, CLAVIER establishes a large data base, tools, and methodologies, which contribute to reasonable planning for a successful development of society and economy in CEEC under climate change conditions. Current regional climate projections show a strong warming and drying during the summer months, which seems partly due to a systematic error in model simulations. Detailed validation of the CLAVIER simulations, which goes much beyond this paper, is needed, and the results have to be related to possible climate changes projected for the region in future simulations
Links between self-injury and suicidality in autism
Autistic individuals without intellectual disability are at heightened risk of self-injury, and appear to engage in it for similar reasons as non-autistic people. A wide divergence of autistic perspectives on self-injury, including those who frame it as a helpful coping mechanism, motivate investigating the link between self-injury, suicide ideation and attempts which has been reported in typically-developing individuals
Speleothem record of mild and wet mid-Pleistocene climate in northeast Greenland
The five interglacials before the Mid-Brunhes Event (MBE) [c.430 thousand years (ka) ago] are generally considered to be globally cooler than those post-MBE. Inhomogeneities exist regionally, however, which suggest that the Arctic was warmer than present during Marine Isotope Stage (MIS) 15a. Using the first speleothem record for the High Arctic, we investigate the climatic response of northeast Greenland between c.588 and c.549 ka ago. Our results indicate an enhanced warmth of at least +3.5 degrees C relative to the present, leading to permafrost thaw and increased precipitation. We find that delta O-18 of precipitation was at least 3 parts per thousand higher than today and recognize two local cooling events (c.571 and c.594 ka ago) thought to be caused by freshwater forcing. Our results are important for improving understanding of the regional climatic response leading up to the MBE and specifically provide insights into the climatic response of a warmer Arctic
Differential geometry, Palatini gravity and reduction
The present article deals with a formulation of the so called (vacuum)
Palatini gravity as a general variational principle. In order to accomplish
this goal, some geometrical tools related to the geometry of the bundle of
connections of the frame bundle are used. A generalization of
Lagrange-Poincar\'e reduction scheme to these types of variational problems
allows us to relate it with the Einstein-Hilbert variational problem. Relations
with some other variational problems for gravity found in the literature are
discussed.Comment: 28 pages, no figures. (v3) Remarks, discussion and references adde
Design and Fabrication of Electrostatically Actuated Silicon Microshutters Arrays
We have developed a new fabrication process to actuate microshutter arrays (MSA) electrostatically at NASA Goddard Space Flight Center. The microshutters are fabricated on silicon with thin silicon nitride membranes. A pixel size of each microshutter is 100 x 200 micrometers 2. The microshutters rotate 90 degrees on torsion bars. The selected microshutters are actuated, held, and addressed electrostatically by applying voltages on the electrodes the front and back sides of the microshutters. The atomic layer deposition (ALD) of aluminum oxide was used to insulate electrodes on the back side of walls; the insulation can withstand over 100 V. The ALD aluminum oxide is dry etched, and then the microshutters are released in vapor HF
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