798 research outputs found
Influence of genotype and age of explant source on the capacity for somatic embryogenesis of two Cavendish banana cultivars (Musa acuminata Colla, AAA)
The embryogenic capacities of flower explants from one- and two-week-old male inflorescence buds from Musa acuminata Cavendish, AAA, genotypes ‘Williams’ and ‘Grand Naine’ were investigated. Explants of hands with immature flowers were excised and induced for embryogenesis. Highlysignificant differences were found in the embryogenic response, depending on the genotype and the developmental stage of the buds from which the explants were excised. After four months of induction, the total percentage of callus formed ranged from 97.81% in explants of two-week-old ‘Williams’ buds to 52.11% in explants of two-week-old ‘Grand Naine’ buds. Embryogenic callus formation was, on average, higher in the two-week-old ‘Williams’ explants (10.01%) than in the one-week-old explants (0.78%). The opposite was true for ‘Grand Naine’, with 7.51% embryogenic callus produced in explants of one-week-old buds compared to 2.49% in two-week-old buds. Selected embryogenic calluses that were successfully established on proliferation medium led to embryogenic cell suspensions with good regeneration capacities. Fifteen to thirty-five percent of the embryos germinated, demonstrated high plant-conversion capacity (99%). The effect of the interaction between the developmental age ofexplant and the genotype on the embryogenesis response is discussed
Intentional injury reported by young people in the Federated States of Micronesia, Kingdom of Tonga and Vanuatu
<p>Abstract</p> <p>Background</p> <p>Intentional injury presents a threat to the physical and psychological well being of young people, especially in developing countries, which carry the greatest part of the global injury burden. While the importance of this problem is recognized, there are limited population data in low and middle income countries that can guide public health action. The present study investigates the prevalence and distribution of intentional injury among young people in three Pacific Island societies, and examines behavioural and psychosocial factors related to risk of intentional injury.</p> <p>Methods</p> <p>Population surveys were conducted with <b>s</b>tudents aged 11–17 years in Pohnpei State in the Federated States of Micronesia (n = 1495), the Kingdom of Tonga (n = 2808) and Vanuatu (n = 4474). Surveys measured self-reported injury and intentional injury, sources of intentional injury, and the range of behavioural, psychological, educational and social variables that may be related to injury risk.</p> <p>Results</p> <p>Among boys and girls aged 14–17 years the respective period prevalence of intentional injury was 62% and 56% in Pohnpei, 58% and 41% in Tonga, and 33% and 24% in Vanuatu. The prevalence of intentional injury declined with age in Tonga and Vanuatu, but there was little evidence of an age-trend in Pohnpei. Across the three societies, the major sources of intentional injury among boys were 'other persons' followed by boyfriends/girlfriends and fathers. Mothers, boyfriends/girlfriends and other persons were primary sources of injury among girls. An intentional injury was reported more often by those who had been bullied (OR 1.40–1.66, P < 0.05), by regular smokers in Tonga and Vanuatu (OR 1.52–2.21, P < 0.05), and illicit drug users in Pohnpei and Vanuatu (OR 1.87–1.92, P < 0.05).</p> <p>Conclusion</p> <p>Intentional injury was reported extensively in these three populations. Interventions directed towards the school environment and which take into account the role of bullying and drug use need to be considered.</p
Spatial heterogeneity of habitat suitability for Rift Valley fever occurrence in Tanzania: an ecological niche modelling approach
Despite the long history of Rift Valley fever (RVF) in Tanzania, extent of its suitable habitat in the country remains unclear. In this study we investigated potential effects of temperature, precipitation, elevation, soil type, livestock density, rainfall pattern, proximity to wild animals, protected areas and forest on the habitat suitability for RVF occurrence in Tanzania. Presence-only records of 193 RVF outbreak locations from 1930 to 2007 together with potential predictor variables were used to model and map the suitable habitats for RVF occurrence using ecological niche modelling. Ground-truthing of the model outputs was conducted by comparing the levels of RVF virus specific antibodies in cattle, sheep and goats sampled from locations in Tanzania that presented different predicted habitat suitability values. Habitat suitability values for RVF occurrence were higher in the northern and central-eastern regions of Tanzania than the rest of the regions in the country. Soil type and precipitation of the wettest quarter contributed equally to habitat suitability (32.4% each), followed by livestock density (25.9%) and rainfall pattern (9.3%). Ground-truthing of model outputs revealed that the odds of an animal being seropositive for RVFV when sampled from areas predicted to be most suitable for RVF occurrence were twice the odds of an animal sampled from areas least suitable for RVF occurrence (95% CI: 1.43, 2.76, p < 0.001). The regions in the northern and central-eastern Tanzania were more suitable for RVF occurrence than the rest of the regions in the country. The modelled suitable habitat is characterised by impermeable soils, moderate precipitation in the wettest quarter, high livestock density and a bimodal rainfall pattern. The findings of this study should provide guidance for the design of appropriate RVF surveillance, prevention and control strategies which target areas with these characteristics
Are sedatives and hypnotics associated with increased suicide risk of suicide in the elderly?
<p>Abstract</p> <p>Background</p> <p>While antidepressant-induced suicidality is a concern in younger age groups, there is mounting evidence that these drugs may reduce suicidality in the elderly. Regarding a possible association between other types of psychoactive drugs and suicide, results are inconclusive. Sedatives and hypnotics are widely prescribed to elderly persons with symptoms of depression, anxiety, and sleep disturbance. The aim of this case-control study was to determine whether specific types of psychoactive drugs were associated with suicide risk in late life, after controlling for appropriate indications.</p> <p>Methods</p> <p>The study area included the city of Gothenburg and two adjacent counties (total 65+ population 210 703 at the start of the study). A case controlled study of elderly (65+) suicides was performed and close informants for 85 suicide cases (46 men, 39 women mean age 75 years) were interviewed by a psychiatrist. A population based comparison group (n = 153) was created and interviewed face-to-face. Primary care and psychiatric records were reviewed for both suicide cases and comparison subjects. All available information was used to determine past-month mental disorders in accordance with DSM-IV.</p> <p>Results</p> <p>Antidepressants, antipsychotics, sedatives and hypnotics were associated with increased suicide risk in the crude analysis. After adjustment for affective and anxiety disorders neither antidepressants in general nor SSRIs showed an association with suicide. Antipsychotics had no association with suicide after adjustment for psychotic disorders. Sedative treatment was associated with an almost fourteen-fold increase of suicide risk in the crude analyses and remained an independent risk factor for suicide even after adjustment for any DSM-IV disorder. Having a current prescription for a hypnotic was associated with a four-fold increase in suicide risk in the adjusted model.</p> <p>Conclusion</p> <p>Sedatives and hypnotics were both associated with increased risk for suicide after adjustment for appropriate indications. Given the extremely high prescription rates, a careful evaluation of the suicide risk should always precede prescribing a sedative or hypnotic to an elderly individual.</p
Numerical study on load-bearing capabilities of beam-like lattice structures with three different unit cells
The design and analysis of lattice structures manufactured using Additive Manufacturing (AM) technique is a new approach to create lightweight high-strength components. However, it is difficult for engineers to choose the proper unit cell for a certain function structure and loading case. In this paper, three beam-like lattice structures with triangular prism, square prism and hexagonal prism were designed, manufactured by SLM process using AlSi10Mg and tested. The mechanical performances of lattice structures with equal relative density, equal base area and height, and equal length for all unit cells were conducted by Finite Element Analysis (FEA). It was found that effective Young’s modulus is proportional to relative density, but with different affecting levels. When the lattice structures are designed with the same relative density or the same side lengths, the effective Young’s modulus of lattice structure with triangular prism exhibits the maximum value for both cases. When the lattice structures are designed with the same base areas for all unit cells, the effective Young’s modulus of lattice structures with square prism presents the maximum. FEA results also show that the maximum stress of lattice structures with triangular prisms in each comparison is at the lowest level and the stiffness-to-mass ratio remains at the maximum value, showing the overwhelming advantages in terms of mechanical strength. The excellent agreements between numerical results and experimental tests reveal the validity of FEA methods applied. The results in this work provide an explicit guideline to fabricate beam-like lattice structures with the best tensile and bending capabilities
Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector
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 cos2Δϕ modulation for all ΣETPb ranges and particle pT
Search for the neutral Higgs bosons of the minimal supersymmetric standard model in pp collisions at root s=7 TeV with the ATLAS detector
A search for neutral Higgs bosons of the Minimal Supersymmetric Standard Model (MSSM) is reported. The analysis is based on a sample of proton-proton collisions at a centre-of-mass energy of 7TeV recorded with the ATLAS detector at the Large Hadron Collider. The data were recorded in 2011 and correspond to an integrated luminosity of 4.7 fb-1 to 4.8 fb-1. Higgs boson decays into oppositely-charged muon or τ lepton pairs are considered for final states requiring either the presence or absence of b-jets. No statistically significant excess over the expected background is observed and exclusion limits at the 95% confidence level are derived. The exclusion limits are for the production cross-section of a generic neutral Higgs boson, φ, as a function of the Higgs boson mass and for h/A/H production in the MSSM as a function of the parameters mA and tan β in the mhmax scenario for mA in the range of 90GeV to 500 GeV. Copyright CERN
Search for R-parity-violating supersymmetry in events with four or more leptons in sqrt(s) =7 TeV pp collisions with the ATLAS detector
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 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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