1,240 research outputs found

    An Examination of South Carolina’s Institutions of Reform and Their Impact on the Self-Narratives of African American Men

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    In the State of South Carolina (SC), African American male adolescents disproportionately face disciplinary action in public schools and other institutions. In 2013, South Carolina’s Department of Juvenile Justice (SCDJJ) released data that listed Black male children comprising 57% of all juvenile referrals in the state. This disproportionate trend is also present in South Carolina’s correctional system. In 2013, South Carolina’s Department of Corrections (SCDOC) reported that out of 20,777 male prisoners, 13,631 were Black. For adolescents or young adults looking to continue their education, alternative programs are available. One program that captures educationally displaced children in South Carolina is “Construct, SC”1 (CSC). It is one of four affiliate programs of a national non-profit, “Construct, USA”2 (CUSA), that operates in the state. The research carried out considers the efficacy of one affiliate to deliver program outcomes and includes critical insights of the author working at that affiliate’s program site. The racial and correctional implications of school removal inform discussions on South Carolina’s institutional framework in the lives of Black adolescents and young adults today. A critical theoretical approach is employed in this paper to examine the state agencies most prevalent in the lives of Black men, in a bid to ascertain how the observed disproportionate trends developed. The paper incorporates five interviews conducted with men enrolled in CSC. The interviews outline their experiences in public school, the juvenile justice and state corrections systems. This paper argues that the structural inequalities that impact African Americans today correlate closely with those of South Carolina’s slave-holding past. Indeed this history is the basis for the state’s development and upkeep of its contemporary correctional culture and delinquency reform strategies against Black boys and men. Facilities that were established and in operation until the 1970s are understood to be at the epicenter of subsequent inter-generational societal and achievement deficits among Black men in the state

    A comparison of dry and wet season aerosol number fluxes over the Amazon rain forest

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    Vertical number fluxes of aerosol particles and vertical fluxes of CO(2) were measured with the eddy covariance method at the top of a 53 m high tower in the Amazon rain forest as part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) experiment. The observed aerosol number fluxes included particles with sizes down to 10 nm in diameter. The measurements were carried out during the wet and dry season in 2008. In this study focus is on the dry season aerosol fluxes, with significant influence from biomass burning, and these are compared with aerosol fluxes measured during the wet season. Net particle deposition fluxes dominated in daytime in both seasons and the deposition flux was considerably larger in the dry season due to the much higher dry season particle concentration. The particle transfer velocity increased linearly with increasing friction velocity in both seasons. The difference in transfer velocity between the two seasons was small, indicating that the seasonal change in aerosol number size distribution is not enough for causing any significant change in deposition velocity. In general, particle transfer velocities in this study are low compared to studies over boreal forests. The reasons are probably the high percentage of accumulation mode particles and the low percentage of nucleation mode particles in the Amazon boundary layer, both in the dry and wet season, and low wind speeds in the tropics compared to the midlatitudes. In the dry season, nocturnal particle fluxes behaved very similar to the nocturnal CO(2) fluxes. Throughout the night, the measured particle flux at the top of the tower was close to zero, but early in the morning there was an upward particle flux peak that is not likely a result of entrainment or local pollution. It is possible that these morning upward particle fluxes are associated with emission of primary biogenic particles from the rain forest. Emitted particles may be stored within the canopy during stable conditions at nighttime, similarly to CO(2), and being released from the canopy when conditions become more turbulent in the morning.National Institute for Research in the Amazon (INPA)LBACNPq/MCTFAPES

    Aerosol number fluxes over the Amazon rain forest during the wet season

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    Number fluxes of particles with diameter larger than 10 nm were measured with the eddy covariance method over the Amazon rain forest during the wet season as part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) campaign 2008. The primary goal was to investigate whether sources or sinks dominate the aerosol number flux in the tropical rain forest-atmosphere system. During the measurement campaign, from 12 March to 18 May, 60% of the particle fluxes pointed downward, which is a similar fraction to what has been observed over boreal forests. The net deposition flux prevailed even in the absolute cleanest atmospheric conditions during the campaign and therefore cannot be explained only by deposition of anthropogenic particles. The particle transfer velocity v(t) increased with increasing friction velocity and the relation is described by the equation v(t) = 2.4x10(-3)xu(*) where u(*) is the friction velocity. Upward particle fluxes often appeared in the morning hours and seem to a large extent to be an effect of entrainment fluxes into a growing mixed layer rather than primary aerosol emission. In general, the number source of primary aerosol particles within the footprint area of the measurements was small, possibly because the measured particle number fluxes reflect mostly particles less than approximately 200 nm. This is an indication that the contribution of primary biogenic aerosol particles to the aerosol population in the Amazon boundary layer may be low in terms of number concentrations. However, the possibility of horizontal variations in primary aerosol emission over the Amazon rain forest cannot be ruled out.National Institute for Research in the Amazon (INPA)LBA infrastructure teamCNPq/MCT Millennium Institute ProgramFAPES

    Wintertime Arctic Ocean sea water properties and primary marine aerosol concentrations

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    Sea spray aerosols are an important part of the climate system through their direct and indirect effects. Due to the diminishing sea ice, the Arctic Ocean is one of the most rapidly changing sea spray aerosol source areas. However, the influence of these changes on primary particle production is not known. <br><br> In laboratory experiments we examined the influence of Arctic Ocean water temperature, salinity, and oxygen saturation on primary particle concentration characteristics. Sea water temperature was identified as the most important of these parameters. A strong decrease in sea spray aerosol production with increasing water temperature was observed for water temperatures between −1°C and 9°C. Aerosol number concentrations decreased from at least 1400 cm<sup>−3</sup> to 350 cm<sup>−3</sup>. In general, the aerosol number size distribution exhibited a robust shape with one mode close to dry diameter <i>D</i><sub>p</sub> 0.2 μm with approximately 45% of particles at smaller sizes. Changes in sea water temperature did not result in pronounced change of the shape of the aerosol size distribution, only in the magnitude of the concentrations. Our experiments indicate that changes in aerosol emissions are most likely linked to changes of the physical properties of sea water at low temperatures. The observed strong dependence of sea spray aerosol concentrations on sea water temperature, with a large fraction of the emitted particles in the typical cloud condensation nuclei size range, provide strong arguments for a more careful consideration of this effect in climate models

    Caries diagnosis using light fluorescence devices: VistaProof and DIAGNOdent

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    The modern concept of minimally invasive dentistry encompasses early detection of incipient carious lesions and their treatment. Due to the low sensitivity of visual inspection and radiography in the detection of occlusal hidden carious lesions under a macroscopically sound surface, several devices have been developed to increase detection accuracy. DIAGNOdent is one of the tools used for that purpose and VistaProof is a new device recently introduced into the market. They both use light fluorescence to detect incipient carious lesions. DIAGNOdent is based on the fact that carious lesions show higher level of fluorescence than sound tissues when excited by light at specific wavelength. Vistaproof is based on the same principle, but it uses a different wavelength of excitation than DIAGNOdent and a video camera for the detection of fluorescence. The aim of this article was to compare these two devices and present their clinical use

    Human RAD51 rapidly forms intrinsically dynamic nucleoprotein filaments modulated by nucleotide binding state.

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    Formation of RAD51 filaments on single-stranded DNA is an essential event during homologous recombination, which is required for homology search, strand exchange and protection of replication forks. Formation of nucleoprotein filaments (NF) is required for development and genomic stability, and its failure is associated with developmental abnormalities and tumorigenesis. Here we describe the structure of the human RAD51 NFs and of its Walker box mutants using electron microscopy. Wild-type RAD51 filaments adopt an 'open' conformation when compared to a 'closed' structure formed by mutants, reflecting alterations in helical pitch. The kinetics of formation/disassembly of RAD51 filaments show rapid and high ssDNA coverage via low cooperativity binding of RAD51 units along the DNA. Subsequently, a series of isomerization or dissociation events mediated by nucleotide binding state creates intrinsically dynamic RAD51 NFs. Our findings highlight important a mechanistic divergence among recombinases from different organisms, in line with the diversity of biological mechanisms of HR initiation and quality control. These data reveal unexpected intrinsic dynamic properties of the RAD51 filament during assembly/disassembly, which may be important for the proper control of homologous recombination

    Transcriptional dynamics elicited by a short pulse of notch activation involves feed-forward regulation by E(spl)/Hes genes.

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    Dynamic activity of signaling pathways, such as Notch, is vital to achieve correct development and homeostasis. However, most studies assess output many hours or days after initiation of signaling, once the outcome has been consolidated. Here we analyze genome-wide changes in transcript levels, binding of the Notch pathway transcription factor, CSL [Suppressor of Hairless, Su(H), in Drosophila], and RNA Polymerase II (Pol II) immediately following a short pulse of Notch stimulation. A total of 154 genes showed significant differential expression (DE) over time, and their expression profiles stratified into 14 clusters based on the timing, magnitude, and direction of DE. E(spl) genes were the most rapidly upregulated, with Su(H), Pol II, and transcript levels increasing within 5-10 minutes. Other genes had a more delayed response, the timing of which was largely unaffected by more prolonged Notch activation. Neither Su(H) binding nor poised Pol II could fully explain the differences between profiles. Instead, our data indicate that regulatory interactions, driven by the early-responding E(spl)bHLH genes, are required. Proposed cross-regulatory relationships were validated in vivo and in cell culture, supporting the view that feed-forward repression by E(spl)bHLH/Hes shapes the response of late-responding genes. Based on these data, we propose a model in which Hes genes are responsible for co-ordinating the Notch response of a wide spectrum of other targets, explaining the critical functions these key regulators play in many developmental and disease contexts

    Functional significance of the Rad51-Srs2 complex in Rad51 presynaptic filament disruption

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    The SRS2 (Suppressor of RAD Six screen mutant 2) gene encodes an ATP-dependent DNA helicase that regulates homologous recombination in Saccharomyces cerevisiae. Mutations in SRS2 result in a hyper-recombination phenotype, sensitivity to DNA damaging agents and synthetic lethality with mutations that affect DNA metabolism. Several of these phenotypes can be suppressed by inactivating genes of the RAD52 epistasis group that promote homologous recombination, implicating inappropriate recombination as the underlying cause of the mutant phenotype. Consistent with the genetic data, purified Srs2 strongly inhibits Rad51-mediated recombination reactions by disrupting the Rad51-ssDNA presynaptic filament. Srs2 interacts with Rad51 in the yeast two-hybrid assay and also in vitro. To investigate the functional relevance of the Srs2-Rad51 complex, we have generated srs2 truncation mutants that retain full ATPase and helicase activities, but differ in their ability to interact with Rad51. Importantly, the srs2 mutant proteins attenuated for Rad51 interaction are much less capable of Rad51 presynaptic filament disruption. An internal deletion in Srs2 likewise diminishes Rad51 interaction and anti-recombinase activity. We also present evidence that deleting the Srs2 C-terminus engenders a hyper-recombination phenotype. These results highlight the importance of Rad51 interaction in the anti-recombinase function of Srs2, and provide evidence that this Srs2 function can be uncoupled from its helicase activity
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