1,012 research outputs found

    Tracheid Differentiation in Southern Pines During the Dormant Season

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    The differentiation of last-formed xylem tracheids of loblolly (Pinus taeda) and slash (P. elliottii) pines was followed during the overwinter dormant period in the upper Piedmont of South Carolina. Tissue samples taken from the outer portion of the stem of a poletimber-sized tree of each species in November and March were examined microscopically and tracheid transverse cell-wall thickness was measured. Cell double-wall thickness was compared between the two dormant season samples and with that of the previous year's cells of the same radial file. The comparison of cell-wall thickness indicated that the last-formed latewood cells of the annual ring continued to deposit cell-wall material through March and quite possibly into the following spring

    Evaluating Housing Health Hazards: Prevalence, Practices and Priorities in Delhi's Informal Settlements

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    Housing quality is crucially linked to health and sustainability goals, yet there is limited research on informal housing and settlements where housing quality is poor, and the health risks are expected to be greatest. This paper describes the investigation of housing conditions in a low-income resettlement colony in Delhi. A novel transdisciplinary methodology to evaluate multiple housing health hazards and establish intervention priorities in participation with the community was developed. Findings from housing surveys and indoor environmental monitoring were contrasted with a participatory self-assessment—revealing the widespread prevalence of hazards and suboptimal housing conditions as well as substantial differences in priorities, and thus perspectives, between participants and researchers. Focus group discussions explored the findings and built consensus on priorities. Our findings uncovered how poor housing conditions affect daily practices and thus are likely to adversely affect socio-economic development and gender equality. We highlight limitations in current frameworks to assess housing hazards and argue that a transdisciplinary approach is vital to provide a holistic understanding and to develop effective interventions. These insights are crucial to inform inclusive solutions for adequate housing and human settlements that can support improved health and help achieve the sustainable development goals

    Memory effects on descent from nuclear fission barrier

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    Non-Markovian transport equations for nuclear large amplitude motion are derived from the collisional kinetic equation. The memory effects are caused by the Fermi surface distortions and depend on the relaxation time. It is shown that the nuclear collective motion and the nuclear fission are influenced strongly by the memory effects at the relaxation time τ≥5⋅10−23s\tau \geq 5\cdot 10^{-23}{\rm s}. In particular, the descent of the nucleus from the fission barrier is accompanied by characteristic shape oscillations. The eigenfrequency and the damping of the shape oscillations depend on the contribution of the memory integral in the equations of motion. The shape oscillations disappear at the short relaxation time regime at τ→0\tau \to 0, which corresponds to the usual Markovian motion in the presence of friction forces. We show that the elastic forces produced by the memory integral lead to a significant delay for the descent of the nucleus from the barrier. Numerical calculations for the nucleus 236^{236}U shows that due to the memory effect the saddle-to-scission time grows by a factor of about 3 with respect to the corresponding saddle-to-scission time obtained in liquid drop model calculations with friction forces.Comment: 22 pages, 8 figures, submitted to Phys. Rev.

    Geochemical Processes and Controls Affecting Water Quality of the Karst Area of Big Creek near Mt. Judea, Arkansas

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    Karst regions typically are considered to be vulnerable with respect to various land-use activities, owing to the intimate association of surface and groundwater and lack of contaminant attenuation provided by most karst aquifers. Inasmuch as the soluble rocks of the karst landscape can be dissolved to create large, rapid-flow zones that compete successfully with surface streams, groundwater and subsurface flow represent a much larger component of the hydrologic budget in karst regions than in areas where non-soluble rocks predominate. Karst areas typically are distinguished by being unique, but some general approaches can be applied to characterize the hydrology of the area. These approaches include an evaluation of the degree of karstification, the hydrologic attributes of the groundwater flow system, the baseline water quality, the time-of-travel through the karst flow system, and the general flux moving through the system. The nature of potential contaminants and their total mass and range of concentrations are critical to understanding the potential environmental risk. This study describes the characterization of the baseline water quality of the shallow karst Boone aquifer and surface streams and springs to determine major processes and controls affecting water quality in the region, and to assess 2 years of waste spreading. Parameters evaluated include major constituents, contaminants and their breakdown products from the industrial operation of a concentrated animal-feeding operation (CAFO) on Big Creek, the indicator pathogen, E. coli, dissolved oxygen, selected trace metals, and other ancillary water-quality attributes that are directly observable in the environment. Determination of pre-CAFO water quality was accomplished by sampling approximately 40 sites that included wells, springs, and streams

    Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions

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    Three new ruthenium alkylidene complexes (PCy3)Cl2(H2ITap)Ru=CHSPh (9), (DMAP)2Cl2(H2ITap)Ru=CHPh (11) and (DMAP)2Cl2(H2ITap)Ru=CHSPh (12) have been synthesized bearing the pH-responsive H2ITap ligand (H2ITap = 1,3-bis(2’,6’- dimethyl-4’-dimethylaminophenyl)-4,5-dihydroimidazol-2-ylidene). Catalysts 11 and 12 are additionally ligated by two pH-responsive DMAP ligands. The crystal structure was solved for complex 12 by X-ray diffraction. In organic, neutral solution, the catalysts are capable of performing standard ring-opening metathesis polymerization (ROMP) and ring closing metathesis (RCM) reactions with standard substrates. The ROMP with complex 11 is accelerated in the presence of two equiv of H3PO4, but is reduced as soon as the acid amount increased. The metathesis of phenylthiomethylidene catalysts 9 and 12 is sluggish at room temperature, but their ROMP can be dramatically accelerated at 60 °C. Complexes 11 and 12 are soluble in aqueous acid. They display the ability to perform RCM of diallylmalonic acid (DAMA), however, their conversions are very low amounting only to few turnovers before decomposition. However, both catalysts exhibit outstanding performance in the ROMP of dicyclopentadiene (DCPD) and mixtures of DCPD with cyclooctene (COE) in acidic aqueous microemulsion. With loadings as low as 180 ppm, the catalysts afforded mostly quantitative conversions of these monomers while maintaining the size and shape of the droplets throughout the polymerization process. Furthermore, the coagulate content for all experiments staye

    Assessing the infection burden and associated risk factors in children under 5 across Jaipurs urban slums: A feasibility study using a One Health approach

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    Purpose: Infectious diseases are one of the leading causes of death among children under five (U5s) across both India & globally. This is worse in slum environments with poor access to water, sanitation & hygiene (WASH), good nutrition & a safe built environment. / Globally, a One Health (e.g. human, animal & environment) approach is increasingly advocated by WHO, FAO & OIE to reduce infections & antimicrobial resistance. As U5s living in peri-urban slums are exposed to household and community owned companion & livestock animals and pests, the CHIP Consortium hypothesized that utilizing a One Health approach to co-produce behavior change & slum upgrading interventions may reduce this burden where other WASH & nutrition interventions have failed. / This study aimed to assess the feasibility of utilising a One Health approach to assess U5 infection & risk factor prevalence in Jaipurs urban slums prior to undertaking prospective cohort studies involving culture and culture independent sampling of U5s and animals across our study sites in Jaipur, Jakarta & Antofagasta. / Methods: We administered a Rapid Household Survey to 25 purposely selected households across six slums. The questionnaire evaluated infection prevalence, health seeking behaviors, the built environment, presence of animals & pests, and individual to household-level demographics. Associations were calculated using correlations among continuous variables to show strength of significance between continuous variables. / Results: We found a high incidence of infections in children under five at 40%. This was most significantly correlated with accessibility of sanitary toilets (r = .62) and household expenditure. Vaccination coverage and child characteristics (such as size) were minimally correlated, while the presence of animals (pets or pests) was not correlated; the latter was likely due to the design of the survey. / Conclusion: This study found a higher infection prevalence than previous studies. We also found higher correlations with infection incidence among household-level characteristics, indicating that effective interventions need to address both the built and socio-economic environments. A pilot prospective cohort study, which includes researcher observations for the presence of animals to account for inconsistencies in the survey, is now underway

    Search for the decay KL0→3γK_L^0 \rightarrow 3\gamma

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    We performed a search for the decay KL0→3γK_L^0 \rightarrow 3\gamma with the E391a detector at KEK. In the data accumulated in 2005, no event was observed in the signal region. Based on the assumption of KL0→3γK_L^0 \rightarrow 3\gamma proceeding via parity-violation, we obtained the single event sensitivity to be (3.23±0.14)×10−8(3.23\pm0.14)\times10^{-8}, and set an upper limit on the branching ratio to be 7.4×10−87.4\times10^{-8} at the 90% confidence level. This is a factor of 3.2 improvement compared to the previous results. The results of KL0→3γK_L^0 \rightarrow 3\gamma proceeding via parity-conservation were also presented in this paper
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