Impact of Weddell Sea deep convection on natural and anthropogenic carbon in a climate model

A climate model is used to investigate the influence of Weddell Sea open ocean deep convection on anthropogenic and natural carbon uptake for the period 1860-2100. In a three-member ensemble climate change simulation, convection ceases on average by year 1981, weakening the net oceanic cumulative uptake of atmospheric CO2 by year 2100 (-4.3 Pg C) relative to an ocean that has continued convection. This net weakening results from a decrease in anthropogenic carbon uptake (-10.1 Pg C), partly offset by an increase in natural carbon storage (+5.8 Pg C). Despite representing only 4% of its area, the Weddell Sea is responsible for 22% of the Southern Ocean decrease in total climate-driven carbon uptake and 52% of the decrease in the anthropogenic component of oceanic uptake. Although this is a model-specific result, it illustrates the potential of deep convection to produce an inter-model spread in future projections of ocean carbon uptake

Facial asymmetry tracks genetic diversity among Gorilla subspecies

Mountain gorillas are particularly inbred compared to other gorillas and even the most inbred human populations. As mountain gorilla skeletal material accumulated during the 1970s, researchers noted their pronounced facial asymmetry and hypothesized that it reflects a population-wide chewing side preference. However, asymmetry has also been linked to environmental and genetic stress in experimental models. Here, we examine facial asymmetry in 114 crania from three Gorilla subspecies using 3D geometric morphometrics. We measure fluctuating asymmetry (FA), defined as random deviations from perfect symmetry, and population-specific patterns of directional asymmetry (DA). Mountain gorillas, with a current population size of about 1000 individuals, have the highest degree of facial FA (explaining 17% of total facial shape variation), followed by Grauer gorillas (9%) and western lowland gorillas (6%), despite the latter experiencing the greatest ecological and dietary variability. DA, while significant in all three taxa, explains relatively less shape variation than FA does. Facial asymmetry correlates neither with tooth wear asymmetry nor increases with age in a mountain gorilla subsample, undermining the hypothesis that facial asymmetry is driven by chewing side preference. An examination of temporal trends shows that stress-induced developmental instability has increased over the last 100 years in these endangered apes

A Novel Conserved Isoform of the Ubiquitin Ligase UFD2a/UBE4B Is Expressed Exclusively in Mature Striated Muscle Cells

Yeast Ufd2p was the first identified E4 multiubiquitin chain assembly factor. Its vertebrate homologues later referred to as UFD2a, UBE4B or E4B were also shown to have E3 ubiquitin ligase activity. UFD2a function in the brain has been well established in vivo, and in vitro studies have shown that its activity is essential for proper condensation and segregation of chromosomes during mitosis. Here we show that 2 alternative splice forms of UFD2a, UFD2a-7 and -7/7a, are expressed sequentially during myoblast differentiation of C2C12 cell cultures and during cardiotoxin-induced regeneration of skeletal muscle in mice. UFD2a-7 contains an alternate exon 7, and UFD2a-7/7a, the larger of the 2 isoforms, contains an additional novel exon 7a. Analysis of protein or mRNA expression in mice and zebrafish revealed that a similar pattern of isoform switching occurs during developmental myogenesis of cardiac and skeletal muscle. In vertebrates (humans, rodents, zebrafish), UFD2a-7/7a is expressed only in mature striated muscle. This unique tissue specificity is further validated by the conserved presence of 2 muscle-specific splicing regulatory motifs located in the 3′ introns of exons 7 and 7a. UFD2a interacts with VCP/p97, an AAA-type ATPase implicated in processes whose functions appear to be regulated, in part, through their interaction with one or more of 15 previously identified cofactors. UFD2a-7/7a did not interact with VCP/p97 in yeast 2-hybrid experiments, which may allow the ATPase to bind cofactors that facilitate its muscle-specific functions. We conclude that the regulated expression of these UFD2a isoforms most likely imparts divergent functions that are important for myogenisis

ÉTUDE DE L'ENDOMMAGEMENT PAR ÉROSION DE CAVITATION DU CUIVRE DE NUANCE c2

L'endommagement par érosion de cavitation du cuivre de nuance c2 procède en 2 étapes : La phase de déformation au cours de laquelle il y a création de petites cavités accompagnées d'une ondulation de la surface et d'une délinéation des joints de grains et de macles. La seconde phase est la phase d'érosion, caractérisée par l'apparition de décohésions aux joints de grains et de macles, de fissures transgranulaires et de fragmentations des grains par un mécanisme de convergence des cavités.Pure copper cavitation erosion is basically governed by two steps : First deformation process, among wich formation of small pits, surface roughness, delineation of grain and twin boundaries occur. Second erasion process, among wich creation of decohesions of grain and twin boundaries, transgranular cracks and pits converging mechanism is observed

Initial source and site characterization studies for the U. C. San Diego campus

The basic approach of the Campus Laboratory Collaboration (CLC) project is to combine the substantial expertise that exists within the University of California (UC) system in geology, seismology, geotechnical engineering, and structural engineering to evaluate the effects of large earthquakes on UC facilities. These estimates draw upon recent advances in hazard assessment, seismic wave propagation modeling in rocks and soils, dynamic soil testing, and structural dynamics. The UC campuses currently chosen for applications of our integrated methodology are Riverside, San Diego, and Santa Barbara. The basic procedure is first to identify possible earthquake source regions and local campus site conditions that may affect estimates of strong ground motion. Combined geological , geophysical, and geotechnical studies are conducted to characterize each campus with specific focus on the location of particular target buildings of special interest to the campus administrators. The project will then drill and log deep boreholes next to the target structure, to provide direct in-situ measurements of subsurface material properties and to install uphole and downhole 3-component seismic sensors capable of recording both weak and strong motions. The boreholes provide access to deeper materials, below the soil layers, that have relatively high seismic shear-wave velocities. Analysis of conjugate downhole and uphole records provides a basis for optimizing the representation of the low-strain response of the sites. Earthquake rupture scenarios of identified causative faults are combined with the earthquake records and nonlinear soil models to provide site-specific estimates of strong motions at the selected target locations. The predicted ground motions are then used as input to the dynamic analysis of the buildings

Mine seismicity and the Comprehensive Nuclear Test Ban Treaty

Surface and underground mining operations generate seismic ground motions which are created by chemical explosions and ground failures. It may come as a surprise to some that the ground failures (coal bumps, first caves, pillar collapses, rockbursts, etc.) can send signals whose magnitudes are as strong or stronger than those from any mining blast. A verification system that includes seismic, infrasound, hydroacoustic and radionuclide sensors is being completed as part of the CTBT. The largest mine blasts and ground failures will be detected by this system and must be identified as distinct from signals generated by small nuclear explosions. Seismologists will analyze the seismic records and presumably should be able to separate them into earthquake-like and non earthquake-like categories, using a variety of so-called seismic discriminants. Non-earthquake essentially means explosion- or implosion-like. Such signals can be generated not only by mine blasts but also by a variety of ground failures. Because it is known that single-fired chemical explosions and nuclear explosion signals of the same yield give very similar seismic records, the non-earthquake signals will be of concern to the Treaty verification community. The magnitude of the mine-related events is in the range of seismicity created by smaller nuclear explosions or decoupled tests, which are of particular concern under the Treaty. It is conceivable that legitimate mining blasts or some mine-induced ground failures could occasionally be questioned. Information such as shot time, location and design parameters may be all that is necessary to resolve the event identity. In rare instances where the legitimate origin of the event could not be resolved by a consultation and clarification procedure, it might trigger on On-Site Inspection (OSI). Because there is uncertainty in the precise location of seismic event as determined by the International Monitoring System (IMS), the OSI can cover an area of up to 1,000 squared kilometers. In active mining districts this area could include several different mining operations. So, an OSI could be disruptive both to the mining community and to the US Government which must host the foreign inspection team. Accordingly, it is in the best interest of all US parties to try and eliminate the possible occurrence of false alarms. This can be achieved primarily by reducing the ambiguity of mine-induced seismic signals, so that even if these remain visible to the IMS they are clearly consistent with recognizable mining patterns

Identification of a novel prostate cancer susceptibility variant in the KLK3 gene transcript

Genome-wide association studies (GWAS) have identified more than 30 prostate cancer (PrCa) susceptibility loci. One of these (rs2735839) is located close to a plausible candidate susceptibility gene, KLK3, which encodes prostate-specific antigen (PSA). PSA is widely used as a biomarker for PrCa detection and disease monitoring. To refine the association between PrCa and variants in this region, we used genotyping data from a two-stage GWAS using samples from the UK and Australia, and the Cancer Genetic Markers of Susceptibility (CGEMS) study. Genotypes were imputed for 197 and 312 single nucleotide polymorphisms (SNPs) from HapMap2 and the 1000 Genome Project, respectively. The most significant association with PrCa was with a previously unidentified SNP, rs17632542 (combined P = 3.9 9 10-22). This association was confirmed by direct genotyping in three stages of the UK/Australian GWAS, involving 10,405 cases and 10,681 controls (combined P = 1.9 9 10-34). rs17632542 is also shown to be associated with PSA levels and it is a nonsynonymous coding SNP (Ile179Thr) in KLK3. Using molecular dynamic simulation, we showed evidence that this variant has the potential to introduce alterations in the protein or affect RNA splicing. We propose that rs17632542 may directly influence PrCa risk