Ocean forcing of glacier retreat in the western Antarctic Peninsula

In recent decades, hundreds of glaciers draining the Antarctic Peninsula (63° to 70°S) have undergone systematic and progressive change. These changes are widely attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. Here, we identify a strong correspondence between mid-depth ocean temperatures and glacier-front changes along the ~1000-kilometer western coastline. In the south, glaciers that terminate in warm Circumpolar Deep Water have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat. We conclude that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region

Brief Communication: Newly developing rift in Larsen C Ice Shelf presents significant risk to stability

An established rift in the Larsen C Ice Shelf, formerly constrained by a suture zone containing marine ice, grew rapidly during 2014 and is likely in the near future to generate the largest calving event since the 1980s and result in a new minimum area for the ice shelf. Here we investigate the recent development of the rift, quantify the projected calving event and, using a numerical model, assess its likely impact on ice shelf stability. We find that the ice front is at risk of becoming unstable when the anticipated calving event occurs

Gravitational waves from quasi-spherical black holes

A quasi-spherical approximation scheme, intended to apply to coalescing black holes, allows the waveforms of gravitational radiation to be computed by integrating ordinary differential equations.Comment: 4 revtex pages, 2 eps figure

Binary black hole initial data for numerical general relativity based on post-Newtonian data

With the goal of taking a step toward the construction of astrophysically realistic initial data for numerical simulations of black holes, we for the first time derive a family of fully general relativistic initial data based on post-2-Newtonian expansions of the 3-metric and extrinsic curvature without spin. It is expected that such initial data provide a direct connection with the early inspiral phase of the binary system. We discuss a straightforward numerical implementation, which is based on a generalized puncture method. Furthermore, we suggest a method to address some of the inherent ambiguity in mapping post-Newtonian data onto a solution of the general relativistic constraints.Comment: 13 pages, 8 figures, RevTex

Circular orbits of corotating binary black holes: comparison between analytical and numerical results

We compare recent numerical results, obtained within a ``helical Killing vector'' (HKV) approach, on circular orbits of corotating binary black holes to the analytical predictions made by the effective one body (EOB) method (which has been recently extended to the case of spinning bodies). On the scale of the differences between the results obtained by different numerical methods, we find good agreement between numerical data and analytical predictions for several invariant functions describing the dynamical properties of circular orbits. This agreement is robust against the post-Newtonian accuracy used for the analytical estimates, as well as under choices of resummation method for the EOB ``effective potential'', and gets better as one uses a higher post-Newtonian accuracy. These findings open the way to a significant ``merging'' of analytical and numerical methods, i.e. to matching an EOB-based analytical description of the (early and late) inspiral, up to the beginning of the plunge, to a numerical description of the plunge and merger. We illustrate also the ``flexibility'' of the EOB approach, i.e. the possibility of determining some ``best fit'' values for the analytical parameters by comparison with numerical data.Comment: Minor revisions, accepted for publication in Phys. Rev. D, 19 pages, 6 figure

Reconfigurable microfluidic circuits for isolating and retrieving cells of interest

Microfluidic devices are widely used in many fields of biology, but a key limitation is that cells are typically surrounded by solid walls, making it hard to access those that exhibit a specific phenotype for further study. Here, we provide a general and flexible solution to this problem that exploits the remarkable properties of microfluidic circuits with fluid walls─transparent interfaces between culture media and an immiscible fluorocarbon that are easily pierced with pipets. We provide two proofs of concept in which specific cell subpopulations are isolated and recovered: (i) murine macrophages chemotaxing toward complement component 5a and (ii) bacteria (Pseudomonas aeruginosa) in developing biofilms that migrate toward antibiotics. We build circuits in minutes on standard Petri dishes, add cells, pump in laminar streams so molecular diffusion creates attractant gradients, acquire time-lapse images, and isolate desired subpopulations in real time by building fluid walls around migrating cells with an accuracy of tens of micrometers using 3D printed adaptors that convert conventional microscopes into wall-building machines. Our method allows live cells of interest to be easily extracted from microfluidic devices for downstream analyses

Impact of densitized lapse slicings on evolutions of a wobbling black hole

We present long-term stable and second-order convergent evolutions of an excised wobbling black hole. Our results clearly demonstrate that the use of a densitized lapse function extends the lifetime of simulations dramatically. We also show the improvement in the stability of single static black holes when an algebraic densitized lapse condition is applied. In addition, we introduce a computationally inexpensive approach for tracking the location of the singularity suitable for mildly distorted black holes. The method is based on investigating the fall-off behavior and asymmetry of appropriate grid variables. This simple tracking method allows one to adjust the location of the excision region to follow the coordinate motion of the singularity.Comment: 10 pages, 8 figure

Systems Biological Determination of the Epi-Genomic Structure Function Relation:

Despite our knowledge of the sequence of the human genome, the relation of its three-dimensional dynamic architecture with its function – the storage and expression of genetic information – remains one of the central unresolved issues of our age. It became very clear meanwhile that this link is crucial for the entire holistic function of the genome on all genomic coding levels from the DNA sequence to the entire chromosomes. To fulfil the dreams for better diagnostics and treatment in the 21st century (e.g. by gene therapy by inserting a gene into a new global context), we propose here in a unique interdisciplinary project to combine experiment with theory to analyze the (epi-)genomic structure function relationships within the dynamic organization of the -Globin locus, the Immuno Globin loci, and the Tumor Necrosis Factor Alpha regulated SAMD4 region in mouse and human active and inactive cell states, and their global genomic context. The project consists of five work packages (WP1-WP5) and corresponding tasks connected in a system biological approach with iterative use of data, modelling, simulation and experiments via a unique data sharing and visualization platform: In WP1 (Längst, Rippe, Wedemann, Knoch/Grosfeld; T1-T5) to investigate nucleosomal association changes in relation to the DNA sequence and the activity of ATP-driven chromatin remodelling complexes, nucleosome positions will be determined by high-throughput sequencing. The resulting nucleosomal localization probability maps will be evaluated by a novel combination of analysis tools and innovative generic data ontologies. The relation to epigenetic modifications, to the activity of ATP-driven remodelling complexes and compaction degree of nucleosomes will be analysed to understand chromatin morphogenesis and fiber formation. In parallel, in WP2 (Grosveld/Knoch, Cook, Rippe, Längst; T1-T3) we determine by high-throughput monitoring of intra/inter chromosomal contacts and architecture absolute DNA-DNA interaction probability maps for the individual loci and their global context using a novel chromosome conformation capture approach based on deep sequencing. From these the 3D conformation of the chromatin fiber and its higher-order folding into loops and loop clusters can be derived using algorithms recently developed by us. WP3 (Cook, Grosveld/Knoch, Längst; T1-T5) focuses on the determination of transcription rates and structure by qRT-PCR, DNA and RNA fluorescence in situ hybridization using intronic probes and high-resolution laser-scanning and single molecule imaging with advanced image analysis tools. Transcription-dependent changes of active and inactive loci as well as rapid synchronous transcription alteration against the unchanged background is one main interest here. This will yield results in a detailed cartography of the structure-transcription-function dependency and its importance. To rationalize the experimental results theoretically, in WP4 (Wedemann Knoch/Grosveld, Rippe; T1-T3) simulations are made of nucleosomal structure, chromatin fiber conformation and chromosomal architecture using parallel and grid super-computers with ~10.000 CPUs. The impact of different nucleosomal positions and epigenetic modifications on the nucleosomal structure and the chromatin fiber conformation will be assessed by novel Monte Carlo approaches. To understand the higher-order architecture Brownian Dynamics simulations of entire cell nuclei with molecular re

Connecting Numerical Relativity and Data Analysis of Gravitational Wave Detectors

Gravitational waves deliver information in exquisite detail about astrophysical phenomena, among them the collision of two black holes, a system completely invisible to the eyes of electromagnetic telescopes. Models that predict gravitational wave signals from likely sources are crucial for the success of this endeavor. Modeling binary black hole sources of gravitational radiation requires solving the Eintein equations of General Relativity using powerful computer hardware and sophisticated numerical algorithms. This proceeding presents where we are in understanding ground-based gravitational waves resulting from the merger of black holes and the implications of these sources for the advent of gravitational-wave astronomy.Comment: Appeared in the Proceedings of 2014 Sant Cugat Forum on Astrophysics. Astrophysics and Space Science Proceedings, ed. C.Sopuerta (Berlin: Springer-Verlag

Height and risk of death among men and women: aetiological implications of associations with cardiorespiratory disease and cancer mortality

OBJECTIVES: Height is inversely associated with cardiovascular disease mortality risk and has shown variable associations with cancer incidence and mortality. The interpretation of findings from previous studies has been constrained by data limitations. Associations between height and specific causes of death were investigated in a large general population cohort of men and women from the West of Scotland. DESIGN: Prospective observational study. SETTING: Renfrew and Paisley, in the West of Scotland. SUBJECTS: 7052 men and 8354 women aged 45-64 were recruited into a study in Renfrew and Paisley, in the West of Scotland, between 1972 and 1976. Detailed assessments of cardiovascular disease risk factors, morbidity and socioeconomic circumstances were made at baseline. MAIN OUTCOME MEASURES: Deaths during 20 years of follow up classified into specific causes. RESULTS: Over the follow up period 3347 men and 2638 women died. Height is inversely associated with all cause, coronary heart disease, stroke, and respiratory disease mortality among men and women. Adjustment for socioeconomic position and cardiovascular risk factors had little influence on these associations. Height is strongly associated with forced expiratory volume in one second (FEV1) and adjustment for FEV1 considerably attenuated the association between height and cardiorespiratory mortality. Smoking related cancer mortality is not associated with height. The risk of deaths from cancer unrelated to smoking tended to increase with height, particularly for haematopoietic, colorectal and prostate cancers. Stomach cancer mortality was inversely associated with height. Adjustment for socioeconomic position had little influence on these associations. CONCLUSION: Height serves partly as an indicator of socioeconomic circumstances and nutritional status in childhood and this may underlie the inverse associations between height and adulthood cardiorespiratory mortality. Much of the association between height and cardiorespiratory mortality was accounted for by lung function, which is also partly determined by exposures acting in childhood. The inverse association between height and stomach cancer mortality probably reflects Helicobacter pylori infection in childhood resulting inor being associated withshorter height. The positive associations between height and several cancers unrelated to smoking could reflect the influence of calorie intake during childhood on the risk of these cancers