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Turbulent flow at 190 m height above London during 2006-2008: A climatology and the applicability of similarity theory
Flow and turbulence above urban terrain is more complex than above rural terrain, due to the different momentum and heat transfer characteristics that are affected by the presence of buildings (e.g. pressure variations around buildings). The applicability of similarity theory (as developed over rural terrain) is tested using observations of flow from a sonic anemometer located at 190.3 m height in London, U.K. using about 6500 h of data. Turbulence statisticsβdimensionless wind speed and temperature, standard deviations and correlation coefficients for momentum and heat transferβwere analysed in three ways. First, turbulence statistics were plotted as a function only of a local stability parameter z/Ξ (where Ξ is the local Obukhov length and z is the height above ground); the Ο_i/u_* values (i = u, v, w) for neutral conditions are 2.3, 1.85 and 1.35 respectively, similar to canonical values. Second, analysis of urban mixed-layer formulations during daytime convective conditions over London was undertaken, showing that atmospheric turbulence at high altitude over large cities might not behave dissimilarly from that over rural terrain. Third, correlation coefficients for heat and momentum were analyzed with respect to local stability. The results give confidence in using the framework of local similarity for turbulence measured over London, and perhaps other cities. However, the following caveats for our data are worth noting: (i) the terrain is reasonably flat, (ii) building heights vary little over a large area, and (iii) the sensor height is above the mean roughness sublayer depth
Planck intermediate results. XLI. A map of lensing-induced B-modes
The secondary cosmic microwave background (CMB) -modes stem from the
post-decoupling distortion of the polarization -modes due to the
gravitational lensing effect of large-scale structures. These lensing-induced
-modes constitute both a valuable probe of the dark matter distribution and
an important contaminant for the extraction of the primary CMB -modes from
inflation. Planck provides accurate nearly all-sky measurements of both the
polarization -modes and the integrated mass distribution via the
reconstruction of the CMB lensing potential. By combining these two data
products, we have produced an all-sky template map of the lensing-induced
-modes using a real-space algorithm that minimizes the impact of sky masks.
The cross-correlation of this template with an observed (primordial and
secondary) -mode map can be used to measure the lensing -mode power
spectrum at multipoles up to . In particular, when cross-correlating with
the -mode contribution directly derived from the Planck polarization maps,
we obtain lensing-induced -mode power spectrum measurement at a significance
level of , which agrees with the theoretical expectation derived
from the Planck best-fit CDM model. This unique nearly all-sky
secondary -mode template, which includes the lensing-induced information
from intermediate to small () angular scales, is
delivered as part of the Planck 2015 public data release. It will be
particularly useful for experiments searching for primordial -modes, such as
BICEP2/Keck Array or LiteBIRD, since it will enable an estimate to be made of
the lensing-induced contribution to the measured total CMB -modes.Comment: 20 pages, 12 figures; Accepted for publication in A&A; The B-mode map
is part of the PR2-2015 Cosmology Products; available as Lensing Products in
the Planck Legacy Archive http://pla.esac.esa.int/pla/#cosmology; and
described in the 'Explanatory Supplement'
https://wiki.cosmos.esa.int/planckpla2015/index.php/Specially_processed_maps#2015_Lensing-induced_B-mode_ma
Will ocean acidification affect marine microbes?
Author Posting. Β© The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in The ISME Journal 5 (2011): 1-7, doi:10.1038/ismej.2010.79.The pH of the surface ocean is changing as a result of increases in
atmospheric carbon dioxide (CO2) and there are concerns about potential
impacts of lower pH and associated alterations in seawater carbonate
chemistry on the biogeochemical processes in the ocean. However, it is
important to place these changes within the context of pH in the present day
ocean, which is not constant; it varies systematically with season, depth and
along productivity gradients. Yet this natural variability in pH has rarely been
considered in assessments of the effect of ocean acidification on marine
microbes. Surface pH can change as a consequence of microbial utilisation
and production of carbon dioxide, and to a lesser extent other microbiallymediated
processes such as nitrification. Useful comparisons can be made
with microbes in other aquatic environments that readily accommodate very
large and rapid pH change. For example, in many freshwater lakes, pH changes
that are orders of magnitude greater than those projected for the 22nd century
oceans can occur over periods of hours. Marine and freshwater assemblages
have always experienced variable pH conditions. Therefore, an appropriate null
hypothesis may be, until evidence is obtained to the contrary, that major
biogeochemical processes in the oceans other than calcification will not be
fundamentally different under future higher CO2 / lower pH conditions.Funding from the Gordon and Betty Moore Foundation, and logistical support from
the Plymouth Marine Laboratory and the Center for Microbial Oceanography:
Research and Education (National Science Foundation grant EF-0424599) are
gratefully acknowledged
Do personality traits assessed on medical school admission predict exit performance?:A UK-wide longitudinal cohort studyA2
We thank the UKCAT Research Group for funding this independent evaluation and thank Rachel Greatrix and Sandra Nicholson of the UKCAT Consortium for their support throughout this project, and their feedback on the draft paper. We also thank Professor Amanda Lee and Ms Katie Wilde for their input into the application for funding, and ongoing support.Peer reviewedPublisher PD
Past-behavioural versus situational questions in a postgraduate admissions multiple mini-interview: a reliability and acceptability comparison
Spatial identification of potential health hazards: a systematic areal search approach
Integrated metatranscriptomic and metagenomic analyses of stratified microbial assemblages in the open ocean
As part of an ongoing survey of microbial community gene expression in the ocean, we sequenced and compared ~38βMbp of community transcriptomes and ~157βMbp of community genomes from four bacterioplankton samples, along a defined depth profile at Station ALOHA in North Pacific subtropical gyre (NPSG). Taxonomic analysis suggested that the samples were dominated by three taxa: Prochlorales, Consistiales and Cenarchaeales, which comprised 36β69% and 29β63% of the annotated sequences in the four DNA and four cDNA libraries, respectively. The relative abundance of these taxonomic groups was sometimes very different in the DNA and cDNA libraries, suggesting differential relative transcriptional activities per cell. For example, the 125βm sample genomic library was dominated by Pelagibacter (~36% of sequence reads), which contributed fewer sequences to the community transcriptome (~11%). Functional characterization of highly expressed genes suggested taxon-specific contributions to specific biogeochemical processes. Examples included Roseobacter relatives involved in aerobic anoxygenic phototrophy at 75βm, and an unexpected contribution of low abundance Crenarchaea to ammonia oxidation at 125βm. Read recruitment using reference microbial genomes indicated depth-specific partitioning of coexisting microbial populations, highlighted by a transcriptionally active high-light-like Prochlorococcus population in the bottom of the photic zone. Additionally, nutrient-uptake genes dominated Pelagibacter transcripts, with apparent enrichment for certain transporter types (for example, the C4-dicarboxylate transport system) over others (for example, phosphate transporters). In total, the data support the utility of coupled DNA and cDNA analyses for describing taxonomic and functional attributes of microbial communities in their natural habitats.Gordon and Betty Moore FoundationUnited States. Dept. of EnergyNational Science Foundation (U.S.) (Science and Technology Center Award EF0424599
Functional Induction of the Cystine-Glutamate Exchanger System Xc- Activity in SH-SY5Y Cells by Unconjugated Bilirubin
We have previously reported that exposure of SH-SY5Y neuroblastoma cells to unconjugated bilirubin (UCB) resulted in a marked up-regulation of the mRNA encoding for the Na+ -independent cystineβΆglutamate exchanger System Xcβ (SLC7A11 and SLC3A2 genes). In this study we demonstrate that SH-SY5Y cells treated with UCB showed a higher cystine uptake due to a significant and specific increase in the activity of System Xcβ, without the contribution of the others two cystine transporters (XAGβ and GGT) reported in neurons. The total intracellular glutathione content was 2 folds higher in the cells exposed to bilirubin as compared to controls, suggesting that the internalized cystine is used for gluthathione synthesis. Interestingly, these cells were significantly less sensitive to an oxidative insult induced by hydrogen peroxide. If System Xcβ is silenced the protection is lost. In conclusion, these results suggest that bilirubin can modulate the gluthathione levels in neuroblastoma cells through the induction of the System Xcβ, and this renders the cell less prone to oxidative damage
High-Performance Work Systems and Organizational Performance in Emerging Economies: Evidence from MNEs in Turkey
This study examines the association between the usage of high-performance work systems (HPWS) by subsidiaries of multinational enterprises (MNEs) in Turkey and employee and subsidiary level outcomes. The study is based on a survey of 148 MNE subsidiaries operating in Turkey. The results show that the usage of HPWS has a significant positive impact on employee effectiveness. However, their impact on employee skills and development, and organizational financial performance are far less clear. Our findings highlight the extent to which HWPS need to be adapted to take account of context-specific institutional realities. Β© 2014 Springer-Verlag Berlin Heidelberg
Sequential Bottlenecks Drive Viral Evolution in Early Acute Hepatitis C Virus Infection
Hepatitis C is a pandemic human RNA virus, which commonly causes chronic infection and liver disease. The characterization of viral populations that successfully initiate infection, and also those that drive progression to chronicity is instrumental for understanding pathogenesis and vaccine design. A comprehensive and longitudinal analysis of the viral population was conducted in four subjects followed from very early acute infection to resolution of disease outcome. By means of next generation sequencing (NGS) and standard cloning/Sanger sequencing, genetic diversity and viral variants were quantified over the course of the infection at frequencies as low as 0.1%. Phylogenetic analysis of reassembled viral variants revealed acute infection was dominated by two sequential bottleneck events, irrespective of subsequent chronicity or clearance. The first bottleneck was associated with transmission, with one to two viral variants successfully establishing infection. The second occurred approximately 100 days post-infection, and was characterized by a decline in viral diversity. In the two subjects who developed chronic infection, this second bottleneck was followed by the emergence of a new viral population, which evolved from the founder variants via a selective sweep with fixation in a small number of mutated sites. The diversity at sites with non-synonymous mutation was higher in predicted cytotoxic T cell epitopes, suggesting immune-driven evolution. These results provide the first detailed analysis of early within-host evolution of HCV, indicating strong selective forces limit viral evolution in the acute phase of infection
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