5,234 research outputs found
Assessing the Impact of a New Inlet Created by 2012 Hurricane Sandy on the Intensity of Algae Blooms in Bellport Bay NY
Harmful algae blooms (HABs) are a growing ecosystem health issue in environments worldwide, driven by excess nitrogen runoff (Eutrophication) alongside high summer temperatures. HABs strip oxygen from the environment and create toxic environments that impact other primary producers, fish, birds, mammals, reptiles, and any other organisms that enter an affected body of water. The purpose of this study is to analyze the impact of a new inlet, created by Hurricane Sandy in Long Islandâs Bellport Bay, on the concentration of algae blooms during peak blooming periods (Jul-Aug) to inform ecosystem-based management. Google Earth Engine Code Editor and 2008-2017 Landsat 5-8 imagery correlated to the study area were used for imagery and data analysis. The colored infrared (CIR) before & after images of the study area clearly show the new inlet formation and shoal structure in Bellport Bay. Normalized Difference Vegetation Index (NDVI) imagery analysis found a significant decrease in algae bloom concentration, in close proximity to the new inlet formations. Additionally, NDVI imagery analysis found that algae concentration decreased across nearly the entire Moriches and Shinnecock bays, partly due to their pre-existing inlets. This shift is attributed to the differences in local watershed characteristics and waste management strategies across the bays, over the time period of analysis. This study concludes that the formation of new inlets can be beneficial in lowering algae concentrations in appropriate coastal areas afflicted by HABs. However, the primary focus for reducing HABs in all environments must be reductions in anthropogenic nitrogen loading, driven by ineffective land and water management practices overtime
Ailanthus altissima Aqueous Extract Deters Spodoptera frugiperda Oviposition
Ailanthus altissima (Mill.) Swingle (Simaroubaceae), the tree of heaven, is a highly invasive tree species containing phytochemicals with a range of biological activities. Exposure to novel chemistry from invasive plant species may result in changes to established Lepidopteran behaviors, including feeding or oviposition. However, the impact of A. altissima chemistry on insect behavior has not been extensively explored. Therefore, A. altissima extract was tested for oviposition deterrence effects against Spodoptera frugiperda (Smith) (Noctuidae). Oviposition substrates were treated with water-soluble extractions of Zea mays (L), A. altissima, or a combination of both. Moths were then placed in chambers containing different substrate treatments and allowed to oviposit. Given choice, S. frugiperda demonstrated a higher percentage of egg deposition on Z. mays treated substrate compared to water treated substrate or A. altissima treated substrate. Significantly, when Z. mays treated substrate was subsequently treated with A. altissima extract, S. frugiperda was deterred from laying eggs on its preferred substrate (Z. mays) in a concentration-dependent manner. This observed change in behavior suggests that the deterrent properties of A. altissima phytochemicals may have economically important crop protection applications in controlling pest species like S. frugiperda
Black hole masses and enrichment of z ~ 6 SDSS quasars
We present sensitive near-infrared spectroscopic observations for a sample of
five z ~ 6 quasars. These are amongst the most distant, currently known quasars
in the universe. The spectra have been obtained using ISAAC at the VLT and
include the CIV, MgII and FeII lines. We measure the FeII/MgII line ratio, as
an observational proxy for the Fe/alpha element ratio. We derive a ratio of
2.7+/-0.8 for our sample, which is similar to that found for lower redshift
quasars, i.e., we provide additional evidence for the lack of evolution in the
FeII/MgII line ratio of quasars up to the highest redshifts. This result
demonstrates that the sample quasars must have undergone a major episode of
iron enrichment in less than one Gyr and star formation must have commenced at
z > 8. The linewidths of the MgII and CIV lines give two estimates for the
black hole masses. A third estimate is given by assuming that the quasars emit
at their Eddington luminosity. The derived masses using these three methods
agree well, implying that the quasars are not likely to be strongly lensed. We
derive central black hole masses of 0.3-5.2 10^9 solar masses. We use the
difference between the redshift of MgII (a proxy for the systemic redshift of
the quasar) and the onset of the Gunn Peterson trough to derive the extent of
the ionized Stromgren spheres around our target quasars. The derived physical
radii are about five Mpc. Using a simple ionization model, the emission of the
central quasars would need of order 10^6-10^8 year to create these cavities in
a surrounding intergalactic medium with a neutral fraction between 0.1 and 1.0.
As the e-folding time scale for the central accreting black hole is on the
order of a few times 10^7 year, it can grow by one e-folding or less within
this time span.Comment: Accepted by ApJ, 15 pages, 8 figure
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Dual gene activation and knockout screen reveals directional dependencies in genetic networks.
Understanding the direction of information flow is essential for characterizing how genetic networks affect phenotypes. However, methods to find genetic interactions largely fail to reveal directional dependencies. We combine two orthogonal Cas9 proteins from Streptococcus pyogenes and Staphylococcus aureus to carry out a dual screen in which one gene is activated while a second gene is deleted in the same cell. We analyze the quantitative effects of activation and knockout to calculate genetic interaction and directionality scores for each gene pair. Based on the results from over 100,000 perturbed gene pairs, we reconstruct a directional dependency network for human K562 leukemia cells and demonstrate how our approach allows the determination of directionality in activating genetic interactions. Our interaction network connects previously uncharacterized genes to well-studied pathways and identifies targets relevant for therapeutic intervention
Adolescents' understanding of obesity: a qualitative study from rural South Africa.
Funder: Department of HealthBACKGROUND: Levels of obesity are rising in South Africa, notably among adolescent females. Excessive energy-dense diets and physical inactivity are among the factors contributing to this increase. Given that these factors are largely behavioural, understanding young people's views of obesity can contribute to more targeted behavioural interventions. Yet little is known of how rural South African adolescents view obesity. OBJECTIVES: The aim of this study was to explore rural South African adolescents' views of obesity, including their understanding of its causes, consequences, and solutions. METHODS: This qualitative study took place within the MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt) study area, in rural northeast South Africa. Three focus group discussions were held with male (n = 16) and female adolescents (n = 15), aged 14-19 years in 2018. Data were analysed using thematic analysis and the Social Cognitive Theory used to frame the findings. RESULTS: Participants presented conflicting views of obesity, with both positive and negative opinions expressed. Causes of obesity were seen to be multifactorial, including genetics, diet, lack of physical activity, and HIV treatment. Adolescents proposed medication and hospitalisation as ways to address obesity. When discussing interventions to address obesity, adolescents expressed the need for more information, suggesting that providing information to both themselves and their family members as part of interventions would be important. CONCLUSIONS: Rural South African adolescents have a complex perspective of obesity, likely driven in part by the current nutrition transition underway and do not inherently see individual behaviour as a driver or mitigator of obesity. Complex interventions including the involvement of other household members are needed to change adolescents' views on the role of the individual, and ultimately, change both individual and household behaviour to prevent obesity
Mineral deposition and vascular invasion of hydroxyapatite reinforced collagen scaffolds seeded with human adipose-derived stem cells
Background:
Collagen-based scaffolds reinforced with hydroxyapatite (HA) are an attractive choice for bone tissue engineering because their composition mimics that of bone. We previously reported the development of compression-molded collagen-HA scaffolds that exhibited high porosity, interconnected pores, and mechanical properties that were well-suited for surgical handling and fixation. The objective of this study was to investigate these novel collagen-HA scaffolds in combination with human adipose-derived stem cells (hASCs) as a template for bone formation in a subcutaneous athymic mouse model.
Methods:
Collagen-HA scaffolds and collagen-only scaffolds were fabricated as previously described, and a clinically approved bone void filler was used as a control for the material. Constructs were seeded with hASCs and were pre-treated with either control or osteogenic media. A cell-free group was also included. Scaffolds were implanted subcutaneously in the backs of athymic nude mice for 8âweeks. Mineral deposition was quantified via micro-computed tomography. Histological and immunofluorescence images of the explants were used to analyze their vascular invasion, remodeling and cellularity.
Results:
Cell-free collagen-HA scaffolds and those that were pre-seeded with osteogenically differentiated hASCs supported mineral deposition and vascular invasion at comparable rates, while cell-seeded constructs treated with the control medium showed lower mineralization after implantation. HA-reinforcement allowed collagen constructs to maintain their shape, provided improved cell-tissue-scaffold integration, and resulted in a more organized tissue when pre-treated in an osteogenic medium. Scaffold type and pre-treatment also determined osteoclast activity and therefore potential remodeling of the constructs.
Conclusions:
The results of this study cumulatively indicate that treatment medium and scaffold composition direct mineralization and angiogenic tissue formation in an ectopic model. The data suggest that it may be necessary to match the scaffold with a particular cell type and cell-specific pre-treatment to achieve optimal bone formation
Giant negative magnetoresistance in semiconductors doped by multiply charged deep impurities
A giant negative magnetoresistance has been observed in bulk germanium doped
with multiply charged deep impurities. Applying a magnetic field the resistance
may decrease exponentially at any orientation of the field. A drop of the
resistance as much as about 10000% has been measured at 6 T. The effect is
attributed to the spin splitting of impurity ground state with a very large
g-factor in the order of several tens depending on impurity.Comment: 4 pages, 4 figure
Influence of Total Western Diet on Docosahexaenoic Acid Suppression of Silica-Triggered Lupus Flaring in NZBWF1 Mice
Lupus is a debilitating multi-organ autoimmune disease clinically typified by periods of flare and remission. Exposing lupus-prone female NZBWF1 mice to crystalline silica (cSiO2), a known human autoimmune trigger, mimics flaring by inducing interferon-related gene (IRG) expression, inflammation, ectopic lymphoid structure (ELS) development, and autoantibody production in the lung that collectively accelerate glomerulonephritis. cSiO2-triggered flaring in this model can be prevented by supplementing mouse diet with the Ï-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA). A limitation of previous studies was the use of purified diet that, although optimized for rodent health, does not reflect the high American intake of saturated fatty acid (SFA), Ï-6 PUFAs, and total fat. To address this, we employed here a modified Total Western Diet (mTWD) emulating the 50th percentile U.S. macronutrient distribution to discern how DHA supplementation and/or SFA and Ï-6 reduction influences cSiO2-triggered lupus flaring in female NZBWF1 mice. Six-week-old mice were fed isocaloric experimental diets for 2 wks, intranasally instilled with cSiO2 or saline vehicle weekly for 4 wks, and tissues assessed for lupus endpoints 11 wks following cSiO2 instillation. In mice fed basal mTWD, cSiO2 induced robust IRG expression, proinflammatory cytokine and chemokine elevation, leukocyte infiltration, ELS neogenesis, and autoantibody production in the lung, as well as early kidney nephritis onset compared to vehicle-treated mice fed mTWD. Consumption of mTWD containing DHA at the caloric equivalent to a human dose of 5 g/day dramatically suppressed induction of all lupus-associated endpoints. While decreasing SFA and Ï-6 in mTWD modestly inhibited some disease markers, DHA addition to this diet was required for maximal protection against lupus development. Taken together, DHA supplementation at a translationally relevant dose was highly effective in preventing cSiO2-triggered lupus flaring in NZBWF1 mice, even against the background of a typical Western diet
Effect of vessel wettability on the foamability of "ideal" surfactants and "real-world" beer heads
The ability to tailor the foaming properties of a solution by controlling its chemical composition is highly desirable and has been the subject of extensive research driven by a range of applications. However, the control of foams by varying the wettability of the foaming vessel has been less widely reported. This work investigates the effect of the wettability of the side walls of vessels used for the in situ generation of foam by shaking aqueous solutions of three different types of model surfactant systems (non-ionic, anionic and cationic surfactants) along with four different beers (Guinness Original, Banksâs Bitter, Bass No 1 and Harvest Pale). We found that hydrophilic vials increased the foamability only for the three model systems but increased foam stability for all foams except the model cationic system. We then compared stability of beer foams produced by shaking and pouring and demonstrated weak qualitative agreement between both foam methods. We also showed how wettability of the glass controls bubble nucleation for beers and champagne and used this effect to control exactly where bubbles form using simple wettability patterns
Do female association preferences predict the likelihood of reproduction?
Sexual selection acting on male traits through female mate choice is commonly inferred from female association preferences in dichotomous mate choice experiments. However, there are surprisingly few empirical demonstrations that such association preferences predict the likelihood of females reproducing with a particular male. This information is essential to confirm association preferences as good predictors of mate choice. We used green swordtails (<i>Xiphophorus helleri</i>) to test whether association preferences predict the likelihood of a female reproducing with a male. Females were tested for a preference for long- or short-sworded males in a standard dichotomous choice experiment and then allowed free access to either their preferred or non-preferred male. If females subsequently failed to produce fry, they were provided a second unfamiliar male with similar sword length to the first male. Females were more likely to reproduce with preferred than non-preferred males, but for those that reproduced, neither the status (preferred/non-preferred) nor the sword length (long/short) of the male had an effect on brood size or relative investment in growth by the female. There was no overall preference based on sword length in this study, but male sword length did affect likelihood of reproduction, with females more likely to reproduce with long- than short-sworded males (independent of preference for such males in earlier choice tests). These results suggest that female association preferences are good indicators of female mate choice but that ornament characteristics of the male are also important
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