204 research outputs found
Environmental Health: Pest and Solid Waste Management
Presented for World Environmental Health Day, September 26, 2016 in Greenville, North Carolina
The Supersonic Project: The eccentricity and rotational support of SIGOs and DM GHOSts
A supersonic relative velocity between dark matter (DM) and baryons (the
stream velocity) at the time of recombination induces the formation of low mass
objects with anomalous properties in the early Universe. We widen the scope of
the `Supersonic Project' paper series to include objects we term Dark Matter +
Gas Halos Offset by Streaming (DM GHOSts)--diffuse, DM-enriched structures
formed because of a physical offset between the centers of mass of DM and
baryonic overdensities. We present an updated numerical investigation of DM
GHOSts and Supersonically Induced Gas Objects (SIGOs), including the effects of
molecular cooling, in high resolution hydrodynamic simulations using the AREPO
code. Supplemented by an analytical understanding of their ellipsoidal
gravitational potentials, we study the population-level properties of these
objects, characterizing their morphology, spin, radial mass, and velocity
distributions in comparison to classical structures in non-streaming regions.
The stream velocity causes deviations from sphericity in both the gas and DM
components and lends greater rotational support to the gas. Low mass ( M) objects in regions of streaming demonstrate core-like
rotation and mass profiles. Anomalies in the rotation and morphology of DM
GHOSts could represent an early Universe analogue to observed ultra-faint dwarf
galaxies with variations in DM content and unusual rotation curves.Comment: 26 pages, 20 figure
The Supersonic Project: Star Formation in Early Star Clusters without Dark Matter
The formation mechanism of globular clusters (GCs) has long been debated by
astronomers. It was recently proposed that Supersonically Induced Gas Objects
(SIGOs), which formed in the early Universe due to the supersonic relative
motion of baryons and dark matter at recombination, could be the progenitors of
early globular clusters. In order to become GCs, SIGOs must form stars
relatively efficiently despite forming outside of dark matter halos. We
investigate the potential for star formation in SIGOs using cosmological
hydrodynamic simulations, including the aforementioned relative motions of
baryons and dark matter, molecular hydrogen cooling in primordial gas clouds,
and including explicit star formation. We find that SIGOs do form stars and
that the nascent star clusters formed through this process are accreted by dark
matter halos on short timescales (a few hundreds of Myr). Thus, SIGOs may be
found as intact substructures within these halos, analogous to many present-day
GCs. From this result, we conclude that SIGOs are capable of forming star
clusters with similar properties to globular clusters in the early Universe and
we discuss their detectablity by upcoming JWST surveys.Comment: 11 pages, 5 figure
The Small Subunit of the Mammalian Mitochondrial Ribosome: IDENTIFICATION OF THE FULL COMPLEMENT OF RIBOSOMAL PROTEINS PRESENT
Identification of all the protein components of the small subunit (28 S) of the mammalian mitochondrial ribosome has been achieved by carrying out proteolytic digestions of whole 28 S subunits followed by analysis of the resultant peptides by liquid chromatography and tandem mass spectrometry (LC/MS/MS). Peptide sequence information was used to search the human EST data bases and complete coding sequences of the proteins were assembled. The human mitochondrial ribosome has 29 distinct proteins in the small subunit. Fourteen of this group of proteins are homologs of the Escherichia coli 30 S ribosomal proteins S2, S5, S6, S7, S9, S10, S11, S12, S14, S15, S16, S17, S18, and S21. All of these proteins have homologs in Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae mitochondrial ribosomes. Surprisingly, three variants of ribosomal protein S18 are found in the mammalian and D. melanogaster mitochondrial ribosomes while C. elegans has two S18 homologs. The S18 homologs tend to be more closely related to chloroplast S18s than to prokaryotic S18s. No mitochondrial homologs to prokaryotic ribosomal proteins S1, S3, S4, S8, S13, S19, and S20 could be found in the peptides obtained from the whole 28 S subunit digests or by analysis of the available data bases. The remaining 15 proteins present in mammalian mitochondrial 28 S subunits (MRP-S22 through MRP-S36) are specific to mitochondrial ribosomes. Proteins in this group have no apparent homologs in bacterial, chloroplast, archaebacterial, or cytosolic ribosomes. All but two of these proteins have a clear homolog in D. melanogaster while all but three can be found in the genome of C. elegans. Five of the mitochondrial specific ribosomal proteins have homologs in S. cerevisiae
Combined quantification of the global proteome, phosphoproteome, and proteolytic cleavage to characterize altered platelet functions in the human Scott syndrome
The Scott syndrome is a very rare and likely underdiagnosed bleeding disorder associated with mutations in the gene encoding anoctamin-6. Platelets from Scott patients are impaired in various Ca(2+)-dependent responses, including phosphatidylserine exposure, integrin closure, intracellular protein cleavage, and cytoskeleton-dependent morphological changes. Given the central role of anoctamin-6 in the platelet procoagulant response, we used quantitative proteomics to understand the underlying molecular mechanisms and the complex phenotypic changes in Scott platelets compared with control platelets. Therefore, we applied an iTRAQ-based multi-pronged strategy to quantify changes in (1) the global proteome, (2) the phosphoproteome, and (3) proteolytic events between resting and stimulated Scott and control platelets. Our data indicate a limited number of proteins with decreased (70) or increased (64) expression in Scott platelets, among those we confirmed the absence of anoctamin-6 and the strong up-regulation of aquaporin-1 by parallel reaction monitoring. The quantification of 1566 phosphopeptides revealed major differences between Scott and control platelets after stimulation with thrombin/convulxin or ionomycin. In Scott platelets, phosphorylation levels of proteins regulating cytoskeletal or signaling events were increased. Finally, we quantified 1596 N-terminal peptides in activated Scott and control platelets, 180 of which we identified as calpain-regulated, whereas a distinct set of 23 neo-N termini was caspase-regulated. In Scott platelets, calpain-induced cleavage of cytoskeleton-linked and signaling proteins was downregulated, in accordance with an increased phosphorylation state. Thus, multipronged proteomic profiling of Scott platelets provides detailed insight into their protection against detrimental Ca(2+)-dependent changes that are normally associated with phosphatidylserine exposure
The Supersonic Project: Lighting up the faint end of the JWST UV luminosity function
The James Webb Space Telescope (JWST) is capable of probing extremely early
eras of our Universe when the supersonic relative motions between dark matter
and baryonic overdensities modulate structure formation (). We study
low-mass galaxy formation including this "stream velocity" using high
resolution AREPO hydrodynamics simulations, and present theoretical predictions
of the UV luminosity function (UVLF) and galaxy stellar mass function (GSMF)
down to extremely faint and low mass galaxies (,
. We show that, although the stream velocity
suppresses early star formation overall, it induces a short period of rapid
star formation in some larger dwarfs, leading to an enhancement in the
faint-end of the UVLF at . We demonstrate that JWST observations are
close to this enhanced regime, and propose that the UVLF may constitute an
important probe of the stream velocity at high redshift for JWST and future
observatories.Comment: 12 pages, 7 figure
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