1,281 research outputs found
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Rethinking reactive halogen budgets in the midlatitude lower stratosphere
Current stratospheric models have difficulties in fully explaining the observed midlatitude ozone depletion in the lowermost stratosphere, particularly near the tropopause. Such models assume that only long-lived source gases provide significant contributions to the stratospheric halogen budget, while all the short-lived compounds are removed in the troposphere, the products being rained out. Here we show this assumption to be flawed. Using bromine species as an example, we show that in the lowermost stratosphere, where the observed midlatitude ozone trend maximizes, bromoform (CHBr3) alone likely contributes more inorganic bromine than all the conventional long-lived sources (halons and methyl bromide) combined. Copyright 1999 by the American Geophysical Union
The Largest Gravitational Lens: MACS J0717.5+3745 (z=0.546)
We identify 13 sets of multiply-lensed galaxies around MACS J0717.5+3745
(), outlining a very large tangential critical curve of major axis
\sim2.8\arcmin, filling the field of HST/ACS. The equivalent circular
Einstein radius is \theta_{e}= 55 \pm 3\arcsec (at an estimated source
redshift of ), corresponding to at the
cluster redshift, nearly three times greater than that of A1689 ( for ). The mass enclosed by this critical curve is very large,
and only weakly model dependent, with a
relatively shallow mass profile within , reflecting the unrelaxed
appearance of this cluster. This shallow profile generates a much higher level
of magnification than the well known relaxed lensing clusters of higher
concentration, so that the area of sky exceeding a magnification of
, is \simeq 3.5\sq\arcmin for sources with , making
MACS J0717.5+3745 a compelling target for accessing faint objects at high
redshift. We calculate that only one such cluster, with \theta_{e}\ge
55\arcsec, is predicted within Universes with ,
corresponding to a virial mass , for the
standard (WMAP5 parameters with uncertainties).Comment: 5 pages, 5 figures, accepted to the ApJ Letters; title modified;
minor change
Full-sky maps for gravitational lensing of the CMB
We use the large cosmological Millennium Simulation (MS) to construct the
first all-sky maps of the lensing potential and the deflection angle, aiming at
gravitational lensing of the CMB, with the goal of properly including
small-scale non-linearities and non-Gaussianity. Exploiting the Born
approximation, we implement a map-making procedure based on direct ray-tracing
through the gravitational potential of the MS. We stack the simulation box in
redshift shells up to , producing continuous all-sky maps with
arcminute angular resolution. A randomization scheme avoids repetition of
structures along the line of sight and structures larger than the MS box size
are added to supply the missing contribution of large-scale (LS) structures to
the lensing signal. The angular power spectra of the projected lensing
potential and the deflection-angle modulus agree quite well with semi-analytic
estimates on scales down to a few arcminutes, while we find a slight excess of
power on small scales, which we interpret as being due to non-linear clustering
in the MS. Our map-making procedure, combined with the LS adding technique, is
ideally suited for studying lensing of CMB anisotropies, for analyzing
cross-correlations with foreground structures, or other secondary CMB
anisotropies such as the Rees-Sciama effect.Comment: LaTeX file, 10 pages, MNRAS in press, scales larger than the
Millennium Simulation box size semi-analytically added, maps changed,
references added, typos correcte
Whole-genome association analysis of treatment response in obsessive-compulsive disorder.
Up to 30% of patients with obsessive-compulsive disorder (OCD) exhibit an inadequate response to serotonin reuptake inhibitors (SRIs). To date, genetic predictors of OCD treatment response have not been systematically investigated using genome-wide association study (GWAS). To identify specific genetic variations potentially influencing SRI response, we conducted a GWAS study in 804 OCD patients with information on SRI response. SRI response was classified as 'response' (n=514) or 'non-response' (n=290), based on self-report. We used the more powerful Quasi-Likelihood Score Test (the MQLS test) to conduct a genome-wide association test correcting for relatedness, and then used an adjusted logistic model to evaluate the effect size of the variants in probands. The top single-nucleotide polymorphism (SNP) was rs17162912 (P=1.76 × 10(-8)), which is near the DISP1 gene on 1q41-q42, a microdeletion region implicated in neurological development. The other six SNPs showing suggestive evidence of association (P<10(-5)) were rs9303380, rs12437601, rs16988159, rs7676822, rs1911877 and rs723815. Among them, two SNPs in strong linkage disequilibrium, rs7676822 and rs1911877, located near the PCDH10 gene, gave P-values of 2.86 × 10(-6) and 8.41 × 10(-6), respectively. The other 35 variations with signals of potential significance (P<10(-4)) involve multiple genes expressed in the brain, including GRIN2B, PCDH10 and GPC6. Our enrichment analysis indicated suggestive roles of genes in the glutamatergic neurotransmission system (false discovery rate (FDR)=0.0097) and the serotonergic system (FDR=0.0213). Although the results presented may provide new insights into genetic mechanisms underlying treatment response in OCD, studies with larger sample sizes and detailed information on drug dosage and treatment duration are needed
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Genome-wide association study in obsessive-compulsive disorder: results from the OCGAS.
Obsessive-compulsive disorder (OCD) is a psychiatric condition characterized by intrusive thoughts and urges and repetitive, intentional behaviors that cause significant distress and impair functioning. The OCD Collaborative Genetics Association Study (OCGAS) is comprised of comprehensively assessed OCD patients with an early age of OCD onset. After application of a stringent quality control protocol, a total of 1065 families (containing 1406 patients with OCD), combined with population-based samples (resulting in a total sample of 5061 individuals), were studied. An integrative analyses pipeline was utilized, involving association testing at single-nucleotide polymorphism (SNP) and gene levels (via a hybrid approach that allowed for combined analyses of the family- and population-based data). The smallest P-value was observed for a marker on chromosome 9 (near PTPRD, P=4.13 × 10(-)(7)). Pre-synaptic PTPRD promotes the differentiation of glutamatergic synapses and interacts with SLITRK3. Together, both proteins selectively regulate the development of inhibitory GABAergic synapses. Although no SNPs were identified as associated with OCD at genome-wide significance level, follow-up analyses of genome-wide association study (GWAS) signals from a previously published OCD study identified significant enrichment (P=0.0176). Secondary analyses of high-confidence interaction partners of DLGAP1 and GRIK2 (both showing evidence for association in our follow-up and the original GWAS study) revealed a trend of association (P=0.075) for a set of genes such as NEUROD6, SV2A, GRIA4, SLC1A2 and PTPRD. Analyses at the gene level revealed association of IQCK and C16orf88 (both P<1 × 10(-)(6), experiment-wide significant), as well as OFCC1 (P=6.29 × 10(-)(5)). The suggestive findings in this study await replication in larger samples
Medical Students Educate Teens About Skin Cancer: What Have We Learned?
Skin cancer is a serious societal problem, and public awareness outreach, including to youth, is crucial. Medical students have joined forces to educate adolescents about skin cancer with significant impacts; even one 50-min interactive outreach session led to sustained changes in knowledge and behavior in a cohort of 1,200 adolescents surveyed. Medical students can act as a tremendous asset to health awareness public outreach efforts: enthusiastic volunteerism keeps education cost-effective, results in exponential spread of information, reinforces knowledge and communication skills of future physicians, and can result in tangible, life-saving benefits such as early detection of melanoma
Family-based association study of the BDNF, COMT and serotonin transporter genes and DSM-IV bipolar-I disorder in children
<p>Abstract</p> <p>Background</p> <p>Over the past decade pediatric bipolar disorder has gained recognition as a potentially more severe and heritable form of the disorder. In this report we test for association with genes coding brain-derived neurotrophic factor (<it>BDNF</it>), the serotonin transporter (<it>SLC6A4</it>), and catechol-O-methyltransferase (<it>COMT</it>).</p> <p>Methods</p> <p>Bipolar-I affected offspring triads (N = 173) were drawn from 522 individuals with 2 parents in 332 nuclear families recruited for genetic studies of pediatric psychopathology at the Clinical and Research Program in Pediatric Psychopharmacology and Adult ADHD at Massachusetts General Hospital.</p> <p>Results</p> <p>We failed to identify an association with the val66 allele in BDNF (OR = 1.23, p = 0.36), the COMT-l allele (OR = 1.27, p = 0.1), or the HTTLPR short allele (OR = 0.87, p = 0.38).</p> <p>Conclusion</p> <p>Our study suggests that the markers examined thus far in <it>COMT </it>and <it>SLC6A4 </it>are not associated with pediatric bipolar disorder and that if the val66met marker in <it>BDNF </it>is associated with pediatric bipolar disorder the magnitude of the association is much smaller than first reported.</p
Did a submarine landslide contribute to the 2011 Tohoku tsunami?
Many studies have modeled the Tohoku tsunami of March 11, 2011 as being due entirely to slip on an earthquake fault, but the following discrepancies suggest that further research is warranted. (1) Published models of tsunami propagation and coastal impact underpredict the observed runup heights of up to 40 m measured along the coast of the Sanriku district in the northeast part of Honshu Island. (2) Published models cannot reproduce the timing and high-frequency content of tsunami waves recorded at three nearshore buoys off Sanriku, nor the timing and dispersion properties of the waveforms at offshore DART buoy #21418. (3) The rupture centroids obtained by tsunami inversions are biased about 60 km NNE of that obtained by the Global CMT Project.
Based on an analysis of seismic and geodetic data, together with recorded tsunami waveforms, we propose that, while the primary source of the tsunami was the vertical displacement of the seafloor due to the earthquake, an additional tsunami source is also required. We infer the location of the proposed additional source based on an analysis of the travel times of higher-frequency tsunami waves observed at nearshore buoys. We further propose that the most likely additional tsunami source was a submarine mass failure (SMF—i.e., a submarine landslide). A comparison of pre- and post-tsunami bathymetric surveys reveals tens of meters of vertical seafloor movement at the proposed SMF location, and a slope stability analysis confirms that the horizontal acceleration from the earthquake was sufficient to trigger an SMF. Forward modeling of the tsunami generated by a combination of the earthquake and the SMF reproduces the recorded on-, near- and offshore tsunami observations well, particularly the high-frequency component of the tsunami waves off Sanriku, which were not well simulated by previous models. The conclusion that a significant part of the 2011 Tohoku tsunami was generated by an SMF source has important implications for estimates of tsunami hazard in the Tohoku region as well as in other tectonically similar regions
A filament of dark matter between two clusters of galaxies
It is a firm prediction of the concordance Cold Dark Matter (CDM)
cosmological model that galaxy clusters live at the intersection of large-scale
structure filaments. The thread-like structure of this "cosmic web" has been
traced by galaxy redshift surveys for decades. More recently the Warm-Hot
Intergalactic Medium (WHIM) residing in low redshift filaments has been
observed in emission and absorption. However, a reliable direct detection of
the underlying Dark Matter skeleton, which should contain more than half of all
matter, remained elusive, as earlier candidates for such detections were either
falsified or suffered from low signal-to-noise ratios and unphysical
misalignements of dark and luminous matter. Here we report the detection of a
dark matter filament connecting the two main components of the Abell 222/223
supercluster system from its weak gravitational lensing signal, both in a
non-parametric mass reconstruction and in parametric model fits. This filament
is coincident with an overdensity of galaxies and diffuse, soft X-ray emission
and contributes mass comparable to that of an additional galaxy cluster to the
total mass of the supercluster. Combined with X-ray observations, we place an
upper limit of 0.09 on the hot gas fraction, the mass of X-ray emitting gas
divided by the total mass, in the filament.Comment: Nature, in pres
Skin cancer screening participation and impact on melanoma incidence in Germany – an observational study on incidence trends in regions with and without population-based screening
Background: The SCREEN (Skin Cancer Research to provide Evidence for Effectiveness of Screening in Northern Germany) project involved population-wide skin cancer screening with whole-body examination by general physicians and dermatologists. It was conducted in the German state of Schleswig-Holstein (July 2003–June 2004), but not in the German state of Saarland. Methods: The population-based registries of Schleswig-Holstein and Saarland provided data on melanoma incidence before, during, and after SCREEN to assess the association of skin cancer screening with incidence. Results: Approximately 19% of the Schleswig-Holstein population participated in SCREEN (women: 27%, men: 10%). A total of 52% of all melanomas diagnosed during SCREEN in Schleswig-Holstein were detected as part of the project. Melanoma incidence increased during SCREEN (invasive melanoma in women: +8.9 per 100 000 (95% confidence intervals (CI): 6.1; 11.7); men: +4.0 per 100 000 (95% CI: 1.6; 6.4)) and decreased afterwards (women: −10.6 per 100 000 (95% CI: −13.3; −7.9); men: −4.1 per 100 000 (95% CI: −6.5; −1.7)). Similar changes were not observed in Saarland that had no such project. The differences between the two states were greatest among women, the group with the greater SCREEN participation. Conclusion: The SCREEN project had a substantial impact on melanoma incidence. This is consistent with the impact of effective screening for other cancers
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