1,411 research outputs found

    Visual art inspired by the collective feeding behavior of sand-bubbler crabs

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    Sand--bubblers are crabs of the genera Dotilla and Scopimera which are known to produce remarkable patterns and structures at tropical beaches. From these pattern-making abilities, we may draw inspiration for digital visual art. A simple mathematical model is proposed and an algorithm is designed that may create such sand-bubbler patterns artificially. In addition, design parameters to modify the patterns are identified and analyzed by computational aesthetic measures. Finally, an extension of the algorithm is discussed that may enable controlling and guiding generative evolution of the art-making process

    Attenuation of leukocyte sequestration by selective blockade of PECAM-1 or VCAM-1 in murine endotoxemia

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    Background: Molecular mechanisms regulating leukocyte sequestration into the tissue during endotoxemia and/or sepsis are still poorly understood. This in vivo study investigates the biological role of murine PECAM-1 and VCAM-1 for leukocyte sequestration into the lung, liver and striated skin muscle. Methods: Male BALB/c mice were injected intravenously with murine PECAM-1 IgG chimera or monoclonal antibody (mAb) to VCAM-1 ( 3 mg/kg body weight); controls received equivalent doses of IgG2a ( n = 6 per group). Fifteen minutes thereafter, 2 mg/kg body weight of Salmonella abortus equi endotoxin was injected intravenously. At 24 h after the endotoxin challenge, lungs, livers and striated muscle of skin were analyzed for their myeloperoxidase activity. To monitor intravital leukocyte-endothelial cell interactions, fluorescence videomicroscopy was performed in the skin fold chamber model of the BALB/c mouse at 3, 8 and 24 h after injection of endotoxin. Results: Myeloperoxidase activity at 24 h after the endotoxin challenge in lungs (12,171 +/- 2,357 mU/g tissue), livers ( 2,204 +/- 238 mU/g) and striated muscle of the skin ( 1,161 +/- 110 mU/g) was significantly reduced in both treatment groups as compared to controls, with strongest attenuation in the PECAM-1 IgG treatment group. Arteriolar leukocyte sticking at 3 h after endotoxin (230 +/- 46 cells x mm(-2)) was significantly reduced in both treatment groups. Leukocyte sticking in postcapillary venules at 8 h after endotoxin ( 343 +/- 69 cells/mm(2)) was found reduced only in the VCAM-1-mAb-treated animals ( 215 +/- 53 cells/mm(2)), while it was enhanced in animals treated with PECAM-1 IgG ( 572 +/- 126 cells/mm(2)). Conclusion: These data show that both PECAM-1 and VCAM-1 are involved in endotoxin-induced leukocyte sequestration in the lung, liver and muscle, presumably through interference with arteriolar and/or venular leukocyte sticking. Copyright (C) 2004 S. Karger AG, Basel

    Rickets in Rural Kenyan Preschool Children: Case Report

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    Clinical rickets has not been reported previously in Embu district, Kenya. Baseline clinical assessments performed for a nutrition intervention study in preschool children (n=324) identified 28 cases of rickets (8.6% of study sample). Clinical characteristics included: delays of sitting, walking, and teething; bone and chest deformities; widened wrists and ankles; and bowed lower extremities. Risk factors identified were short duration of breastfeeding with feeding of cereal-based supplements with little or no milk, low calcium intake, limited sunlight exposure. Vitamin D and calcium deficiencies likely contributed to these cases. Treatment with Vitamin D3 and milk resulted inclinical improvement

    The impact of morbidity on food intake in rural Kenyan children

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    Objective: To quantify the effect of common illnesses on energy intake in rural Kenyan children.Design, setting and subjects: Toddlers in rural Kenya (n = 110) were studied longitudinally from 18-30 months of age in the mid-1980s.Outcome measures: Morbidity data were collected weekly using an illness questionnaire and physical inspection. Food intake was quantitatively assessed on two successive days each month. Food intake on days of illness was compared to food intake on days of wellness and during convalescence.Results: Significant decreases in mean daily energy intake were seen between days of wellness vs. days of severe illness. Above usual intakewas observed during convalescence. Girls showed a greater reduction in intake during illness compared to boys. Food intake reductions weregreatest in children with gastrointestinal (diarrhoea) and lower respiratory tract infections, measles and other febrile illnesses. In the case ofsevere illness, a compensatory increase in intake during week one of the convalescence period was observed, being greater in girls (376 kcalvs. 71 kcal extra per day for boys).Conclusion: Food intake is decreased during common acute illnesses in children and increased above their usual intake during convalescence.Food should not be withheld from sick children and feeding should be actively encouraged during illness, particularly during convalescencewith the return of appetite. These data, although somewhat dated, are still applicable to toddlers in rural Africa where malnutrition and feedingpractices have changed very little

    Comparison of blood smear microscopy to a rapid diagnostic test for in-vitro testing for P. Falciparum malaria in Kenyan school children

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    Objective: To compare the diagnostic performance of microscopy using Giemsastained thick and thin blood smears to a rapid malaria dipstick test (RDT) in detecting P. falciparum malaria in Kenyan school children. Design: Randomised, controlled feeding intervention trial from 1998-2001. Setting: Rural Embu district, Kenya. The area is considered endemic for malaria, with four rainy seasons per year. Chloroquine resistance was estimated in 80% of patients. Children had a spleen rate of 45%. Subjects: A sample of 515 rural Kenyan primary school children, aged 7-11 years, who were enrolled in a feeding intervention trial from 1998-2001. Main outcome measures: Percent positive and negative P. falciparum malaria status, sensitivity, specificity and positive and negative predictive values of RDT. Results: For both years, the RDT yielded positive results of 30% in children compared to microscopy (17%). With microscopy as the “gold standard,” RDT yielded a sensitivity of 81.3% in 1998 and 79.3% in 2000. Specificity was 81.6% in 1998 and 78.3% in 2000. Positive predictive value was 47.3% in 1998 and 42.6% in 2000, and negative predictive value was 95.6% in 1998 and 94.9% in 2000. Conclusion: Rapid diagnostic testing is a valuable tool for diagnosis and can shorten the interval for starting treatment, particularly where microscopy may not be feasible due to resource and distance limitations. East African Medical Journal Vol. 85 (11) 2008: pp. 544-54

    Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector

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    The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Observation of associated near-side and away-side long-range correlations in √sNN=5.02  TeV proton-lead collisions with the ATLAS detector

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    Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

    Mantle thermal pulses below the Mid-Atlantic Ridge and temporal variations in the formation of oceanic lithosphere

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    A 20-Myr record of creation of oceanic lithosphere is exposed along a segment of the central Mid-Atlantic Ridge on an uplifted sliver of lithosphere. The degree of melting of the mantle that is upwelling below the ridge, estimated from the chemistry of the exposed mantle rocks, as well as crustal thickness inferred from gravity measurements, show oscillations of 3–4 Myr superimposed on a longer-term steady increase with time. The time lag between oscillations of mantle melting and crustal thickness indicates that the mantle is upwelling at an average rate of 25 mm yr-1, but this appears to vary through time. Slow-spreading lithosphere seems to form through dynamic pulses of mantle upwelling and melting, leading not only to along-axis segmentation but also to across-axis structural variability. Also, the central Mid-Atlantic Ridge appears to have become steadily hotter over the past 20 Myr, possibly owing to north–south mantle flow

    Search for R-parity-violating supersymmetry in events with four or more leptons in sqrt(s) =7 TeV pp collisions with the ATLAS detector

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    A search for new phenomena in final states with four or more leptons (electrons or muons) is presented. The analysis is based on 4.7 fb−1 of s=7  TeV \sqrt{s}=7\;\mathrm{TeV} proton-proton collisions delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in two signal regions: one that requires moderate values of missing transverse momentum and another that requires large effective mass. The results are interpreted in a simplified model of R-parity-violating supersymmetry in which a 95% CL exclusion region is set for charged wino masses up to 540 GeV. In an R-parity-violating MSUGRA/CMSSM model, values of m 1/2 up to 820 GeV are excluded for 10 < tan β < 40
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