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NMHCs and halocarbons in Asian continental outflow during the Transport and Chemical Evolution over the Pacific (TRACE-P) Field Campaign: Comparison with PEM-West B
We present an overview of the spatial distributions of nonmethane hydrocarbons (NMHCs) and halocarbons observed over the western north Pacific as part of the NASA GTE Transport and Chemical Evolution over the Pacific (TRACEāP) airborne field campaign (FebruaryāApril 2001). The TRACEāP data are compared with earlier measurements from the Pacific Rim during the Pacific Exploratory MissionāWest B (PEMāWest B), which took place in FebruaryāMarch 1994, and with emission inventory data for 2000. Despite the limited spatial and temporal data coverage inherent to airborne sampling, mean levels of the longerālived NMHCs (including ethane, ethyne, and benzene) were remarkably similar to our results during the PEMāWest B campaign. By comparison, mixing ratios of the fire extinguisher Halonā1211 (CF2ClBr) increased by about 50% in the period between 1994 and 2001. Southern China (south of 35Ā°N), and particularly the Shanghai region, appears to have been a substantial source of Halonā1211 during TRACEāP. Our previous analysis of the PEMāWest B data employed methyl chloroform (CH3CCl3) as a useful industrial tracer. However, regulations have reduced its emissions to the extent that its mixing ratio during TRACEāP was only oneāthird of that measured in 1994. Methyl chloroform mixing ratio āhot spots,ā indicating regions downwind of continuing emissions, included outflow from the vicinity of Shanghai, China, but particularly high emission ratios relative to CO were observed close to Japan and Korea. Tetrachloroethene (C2Cl4) levels have also decreased significantly, especially north of 25Ā°N, but this gas still remains a useful indicator of northern industrial emissions. Methyl bromide (CH3Br) levels were systematically 1ā2 pptv lower from 1994 to 2001, in accord with recent reports. However, air masses that had been advected over Japan and/or South Korean port cities typically exhibited elevated levels of CH3Br. As a consequence, emissions of CH3Br from Japan and Korea calculated employing CH3Br/CO ratios and scaled to CO emission inventory estimates, were almost as large as for all of south China (south of 35Ā°N). Total east Asian emissions of CH3Br and CH3Cl were estimated to be roughly 4.7 Gg/yr and 167 Gg/yr, respectively, in 2001
Exact Black Holes and Gravitational Shockwaves on Codimension-2 Branes
We derive exact gravitational fields of a black hole and a relativistic
particle stuck on a codimension-2 brane in dimensions when gravity is ruled
by the bulk -dimensional Einstein-Hilbert action. The black hole is locally
the higher-dimensional Schwarzschild solution, which is threaded by a tensional
brane yielding a deficit angle and includes the first explicit example of a
`small' black hole on a tensional 3-brane. The shockwaves allow us to study the
large distance limits of gravity on codimension-2 branes. In an infinite
locally flat bulk, they extinguish as , i.e. as on a 3-brane
in , manifestly displaying the full dimensionality of spacetime. We check
that when we compactify the bulk, this special case correctly reduces to the 4D
Aichelburg-Sexl solution at large distances. Our examples show that gravity
does not really obstruct having general matter stress-energy on codimension-2
branes, although its mathematical description may be more involved.Comment: 18 pages, LaTeX; v2: added references, version to appear in JHE
Halothane hepatitis with renal failure treated with hemodialysis and exchange transfusion
A 38-year-old white female, hepatitis B antigen negative, developed fluminating hepatic failure associated with oliguria and severe azotemia after two halothane anesthesia and without exposure to other hepatotoxic drugs or blood transfusions. She was treated with multiple hemodialysis and exchange blood transfusion. The combined treatment corrected the uremic abnormalities and improved her level of consciousness. The liver and kidney function gradually improved, and she made a complete recovery, the first recorded with hepatic and renal failure under these post-anesthetic conditions. Further evaluation of this combined treatment used for this patient is warranted. Ā© 1974 The Japan Surgical Society
Perturbations of Gauss-Bonnet Black Strings in Codimension-2 Braneworlds
We derive the Lichnerowicz equation in the presence of the Gauss-Bonnet term.
Using the modified Lichnerowicz equation we study the metric perturbations of
Gauss-Bonnet black strings in Codimension-2 Braneworlds.Comment: 26 pages, no figures, clarifying comments and one reference added, to
be published in JHE
Charting the Landscape of Modified Gravity
We explore brane induced gravity on a 3-brane in six locally flat dimensions.
To regulate the short distance singularities in the brane core, we resolve the
thin brane by a cylindrical 4-brane, with the geometry of 4D Minkowski
a circle, which has an axion flux to cancel the vacuum pressure in the compact
direction. We discover a large diversity of possible solutions controlled by
the axion flux, as governed by its boundary conditions. Hence brane induced
gravity models really give rise to a {\it landscape} of vacua, at least
semiclassically. For sub-critical tensions, the crossover scale, below which
gravity may look 4D, and the effective 4D gravitational coupling are sensitive
to vacuum energy. This shows how the vacuum energy problem manifests in brane
induced gravity: instead of tuning the 4D curvature, generically one must tune
the crossover scale. On the other hand, in the near-critical limit, branes live
inside very deep throats which efficiently compactify the angular dimension. In
there, 4D gravity first changes to , and only later to . The crossover
scale saturates at the gravitational see-saw scale, independent of the tension.
Using the fields of static loops on a wrapped brane, we check the perturbative
description of long range gravity below the crossover scale. In sub-critical
cases the scalars are strongly coupled already at the crossover scale even in
the vacuum, because the brane bending is turned on by the axion flux. Near the
critical limit, linearized perturbation theory remains under control below the
crossover scale, and we find that linearized gravity around the vacuum looks
like a scalar-tensor theory.Comment: 47 LaTeX pages, 3 .eps figures, typos fixed to match the published
versio
The Job Search Intensity Supply Curve: How Labor Market Conditions Affect Job Search Effort
During the Great Recession of 2007, unemployment reached nearly 10 percent and the ratio of unemployment to open positions (as measured by the Help Wanted OnLine Index) more than tripled. The weak labor market prompted an unprecedented extension in the length of time in which a claimant can collect unemployment insurance (UI) to 99 weeks, at an expense to date of $226.4 billion. While many claim that extending UI during a recession will reduce search intensity, the effect of weak labor market conditions on search remains a mystery. As a result, policymakers are in the dark as to whether UI extensions reduce already low search effort during recessions or perhaps decrease excessive search, which causes congestion in the labor market. At the same time, modelers of the labor market have little empirical justification for their assumptions on how search intensity changes over the business cycle. This paper develops a search model where the impact of macro labor market conditions on a workerās search effort depends on whether these two factors are substitutes or complements in the job search process. Parameter estimates of the structural model using a sample of unemployment spells from the National Longitudinal Survey of Youth 1997 indicate that macro labor market conditions and individual search effort are complements and move together over the business cycle. The estimation also reveals that more risk-averse and less wealthy individuals exhibit less search effort
Bulk Axions, Brane Back-reaction and Fluxes
Extra-dimensional models can involve bulk pseudo-Goldstone bosons (pGBs)
whose shift symmetry is explicitly broken only by physics localized on branes.
Reliable calculation of their low-energy potential is often difficult because
it requires details of the stabilization of the extra dimensions. In rugby ball
solutions, for which two compact extra dimensions are stabilized in the
presence of only positive-tension brane sources, the effects of brane
back-reaction can be computed explicitly. This allows the calculation of the
shape of the low-energy pGB potential and response of the extra dimensional
geometry as a function of the perturbing brane properties. If the
pGB-dependence is a small part of the total brane tension a very general
analysis is possible, permitting an exploration of how the system responds to
frustration when the two branes disagree on what the proper scalar vacuum
should be. We show how the low-energy potential is given by the sum of brane
tensions (in agreement with common lore) when only the brane tensions couple to
the pGB. We also show how a direct brane coupling to the flux stabilizing the
extra dimensions corrects this result in a way that does not simply amount to
the contribution of the flux to the brane tensions. We calculate the mass of
the would-be zero mode, and briefly describe several potential applications,
including a brane realization of `natural inflation,' and a dynamical mechanism
for suppressing the couplings of the pGB to matter localized on the branes.
Since the scalar can be light enough to be relevant to precision tests of
gravity (in a technically natural way) this mechanism can be relevant to
evading phenomenological bounds.Comment: 36 pages, JHEP styl
Phosphorylated DegU Manipulates Cell Fate Differentiation in the <i>Bacillus subtilis</i> Biofilm<em/>
Cell differentiation is ubiquitous and facilitates division of labor and development. Bacteria are capable of multicellular behaviors that benefit the bacterial community as a whole. A striking example of bacterial differentiation occurs throughout the formation of a biofilm. During Bacillus subtilis biofilm formation, a subpopulation of cells differentiates into a specialized population that synthesizes the exopolysaccharide and the TasA amyloid components of the extracellular matrix. The differentiation process is indirectly controlled by the transcription factor Spo0A that facilitates transcription of the eps and tapA (tasA) operons. DegU is a transcription factor involved in regulating biofilm formation. Here, using a combination of genetics and live single-cell cytological techniques, we define the mechanism of biofilm inhibition at high levels of phosphorylated DegU (DegUā¼P) by showing that transcription from the eps and tapA promoter regions is inhibited. Data demonstrating that this is not a direct regulatory event are presented. We demonstrate that DegUā¼P controls the frequency with which cells activate transcription from the operons needed for matrix biosynthesis in favor of an off state. Subsequent experimental analysis led us to conclude that DegUā¼P functions to increase the level of Spo0Aā¼P, driving cell fate differentiation toward the terminal developmental process of sporulation
Mutation of a single residue, Ī²-glutamate-20, alters proteinālipid interactions of light harvesting complex II
It is well established that assembly of the peripheral antenna complex, LH2, is required for proper photosynthetic membrane biogenesis in the purple bacterium Rhodobacter sphaeroides. The underlying interactions are, as yet, not understood. Here we examined the relationship between the morphology of the photosynthetic membrane and the lipidāprotein interactions at the LH2ālipid interface. The non-bilayer lipid, phosphatidylethanolamine, is shown to be highly enriched in the boundary lipid phase of LH2. Sequence alignments indicate a putative lipid binding site, which includes Ī²-glutamate-20 and the adjacent carotenoid end group. Replacement of Ī²-glutamate-20 with alanine results in significant reduction of phosphatidylethanolamine and concomitant raise in phosphatidylcholine in the boundary lipid phase of LH2 without altering the lipid composition of the bulk phase. The morphology of the LH2 housing membrane is, however, unaffected by the amino acid replacement. In contrast, simultaneous modification of glutamate-20 and exchange of the carotenoid sphaeroidenone with neurosporene results in significant enlargement of the vesicular membrane invaginations. These findings suggest that the LH2 complex, specifically Ī²-glutamate-20 and the carotenoids' polar head group, contribute to the shaping of the photosynthetic membrane by specific interactions with surrounding lipid molecules
Protein kinase Cepsilon is important for migration of neuroblastoma cells
<p>Abstract</p> <p>Background</p> <p>Migration is important for the metastatic capacity and thus for the malignancy of cancer cells. There is limited knowledge on regulatory factors that promote the migration of neuroblastoma cells. This study investigates the hypothesis that protein kinase C (PKC) isoforms regulate neuroblastoma cell motility.</p> <p>Methods</p> <p>PKC isoforms were downregulated with siRNA or modulated with activators and inhibitors. Migration was analyzed with scratch and transwell assays. Protein phosphorylation and expression levels were measured with Western blot.</p> <p>Results</p> <p>Stimulation with 12-<it>O</it>-tetradecanoylphorbol-13-acetate (TPA) induced migration of SK-N-BE(2)C neuroblastoma cells. Treatment with the general protein kinase C (PKC) inhibitor GF109203X and the inhibitor of classical isoforms Gƶ6976 inhibited migration while an inhibitor of PKCĪ² isoforms did not have an effect. Downregulation of PKCĪµ, but not of PKCĪ± or PKCĪ“, with siRNA led to a suppression of both basal and TPA-stimulated migration. Experiments using PD98059 and LY294002, inhibitors of the Erk and phosphatidylinositol 3-kinase (PI3K) pathways, respectively, showed that PI3K is not necessary for TPA-induced migration. The Erk pathway might be involved in TPA-induced migration but not in migration driven by PKCĪµ. TPA induced phosphorylation of the PKC substrate myristoylated alanine-rich C kinase substrate (MARCKS) which was suppressed by the PKC inhibitors. Treatment with siRNA oligonucleotides against different PKC isoforms before stimulation with TPA did not influence the phosphorylation of MARCKS.</p> <p>Conclusion</p> <p>PKCĪµ is important for migration of SK-N-BE(2)C neuroblastoma cells. Neither the Erk pathway nor MARCKS are critical downstream targets of PKCĪµ but they may be involved in TPA-mediated migration.</p
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