3,147 research outputs found

    Bird extinctions threaten to cause disproportionate reductions of functional diversity and uniqueness

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    1. Human activities are driving rapid defaunation of Earth's ecosystems through increasing rates of extinction. However, the ecological consequences of species loss remain unclear, in part due to the limited availability of high-resolution functional trait data. / 2. To address this, we assess how predicted extinctions will reshape avian functional diversity quantified using a multidimensional trait space, or morphospace, reflecting variation in eight key morphological traits closely linked to ecological function across 9943 (>99%) extant bird species. / 3. We show that large regions of this morphospace are represented by very few species and, thus, vulnerable to species loss. We also find evidence that species at highest risk of extinction are both larger and functionally unique in terms of ecological trait dimensions unrelated to size, such as beak shape and wing shape. / 4. Although raw patterns suggest a positive relationship between extinction risk and functional uniqueness, this is removed when accounting for phylogeny and body mass, indicating a dominant role for clade-specific factors, including the combination of larger average body size and higher extinction risk in the non-passerine clade. / 5. Regardless of how a threat is related to uniqueness, we show using simulations that the loss of currently threatened bird species would result in a greater loss of morphological diversity than expected under random extinctions. / 6. Our results suggest that ongoing declines of threatened bird species may drive a disproportionately large loss of morphological diversity, with potentially major consequences for ecosystem functioning

    High Effective Coverage of Vector Control Interventions in Children After Achieving Low Malaria Transmission in Zanzibar, Tanzania.

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    \ud \ud Formerly a high malaria transmission area, Zanzibar is now targeting malaria elimination. A major challenge is to avoid resurgence of malaria, the success of which includes maintaining high effective coverage of vector control interventions such as bed nets and indoor residual spraying (IRS). In this study, caretakers' continued use of preventive measures for their children is evaluated, following a sharp reduction in malaria transmission. A cross-sectional community-based survey was conducted in June 2009 in North A and Micheweni districts in Zanzibar. Households were randomly selected using two-stage cluster sampling. Interviews were conducted with 560 caretakers of under-five-year old children, who were asked about perceptions on the malaria situation, vector control, household assets, and intention for continued use of vector control as malaria burden further decreases. Effective coverage of vector control interventions for under-five children remains high, although most caretakers (65%; 363/560) did not perceive malaria as presently being a major health issue. Seventy percent (447/643) of the under-five children slept under a long-lasting insecticidal net (LLIN) and 94% (607/643) were living in houses targeted with IRS. In total, 98% (628/643) of the children were covered by at least one of the vector control interventions. Seasonal bed-net use for children was reported by 25% (125/508) of caretakers of children who used bed nets. A high proportion of caretakers (95%; 500/524) stated that they intended to continue using preventive measures for their under-five children as malaria burden further reduces. Malaria risk perceptions and different perceptions of vector control were not found to be significantly associated with LLIN effective coverage While the majority of caretakers felt that malaria had been reduced in Zanzibar, effective coverage of vector control interventions remained high. Caretakers appreciated the interventions and recognized the value of sustaining their use. Thus, sustaining high effective coverage of vector control interventions, which is crucial for reaching malaria elimination in Zanzibar, can be achieved by maintaining effective delivery of these interventions

    Covariant Description of Flavor Conversion in the LHC Era

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    A simple covariant formalism to describe flavor and CP violation in the left-handed quark sector in a model independent way is provided. The introduction of a covariant basis, which makes the standard model approximate symmetry structure manifest, leads to a physical and transparent picture of flavor conversion processes. Our method is particularly useful to derive robust bounds on models with arbitrary mechanisms of alignment. Known constraints on flavor violation in the K and D systems are reproduced in a straightforward manner. Assumptions-free limits, based on top flavor violation at the LHC, are then obtained. In the absence of signal, with 100 fb^{-1} of data, the LHC will exclude weakly coupled (strongly coupled) new physics up to a scale of 0.6 TeV (7.6 TeV), while at present no general constraint can be set related to Delta t=1 processes. LHC data will constrain Delta F=2 contributions via same-sign tops signal, with a model independent exclusion region of 0.08 TeV (1.0 TeV). However, in this case, stronger bounds are found from the study of CP violation in D-bar D mixing with a scale of 0.57 TeV (7.2 TeV). In addition, we apply our analysis to models of supersymmetry and warped extra dimension. The minimal flavor violation framework is also discussed, where the formalism allows to distinguish between the linear and generic non-linear limits within this class of models.Comment: 24 pages, 6 figures. Some corrections and clarifications; references added. Matches published versio

    Prevalence of prehypertension and associated cardiovascular risk profiles among prediabetic Omani adults

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    <p>Abstract</p> <p>Background</p> <p>The importance of prediabetes and prehypertension has been demonstrated in several studies especially for primary prevention of CVD. A recent community based cross-sectional study revealed that 40.9 percent Omani adults are prediabetics. This study was undertaken to estimate the prevalence of prehypertension and associated cardiovascular risk profiles in prediabetics. To best of our knowledge, this is the first report on this subject.</p> <p>Methods</p> <p>The study included 327 confirmed pre-diabetic Omani adults, who were analysed for their demographic, metabolic and behavioral characteristics. These characteristics were compared between the three different blood pressure groups to determine the CVD risk factors. Univariate and step-wise multiple logistic regression methods were used to carry out the analysis of the data.</p> <p>Results</p> <p>In this study, the prevalence of prehypertension was 54.1 percent. Males were at higher risk of developing prehypertension as compared to females (OR = 2.30, 95% CI: 1.21, 4.38; P < 0.01). The individuals with higher BMI have two fold more risk of developing prehypertension (OR = 2.25, 95% CI: 1.26, 4.02; P < 0.01). The increased level of OGT enhanced the risk of developing prehypertension (OR = 1.26, 95% CI: 1.06, 1.50; P < 0.01).</p> <p>Conclusion</p> <p>A high prevalence of prehypertension (54.1%) exists in this study population. The major determinants of prehypertension in these prediabetic subjects were male gender, increasing dysglycemia and BMI. Appropriate intervention strategies have been suggested.</p

    Saudi SCD patients’ symptoms and quality of life relative to the number of ED visits

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    Background Individuals living with sickle cell disease (SCD) have significantly increased emergency department (ED) use compared to the general population. In Saudi Arabia, health care is free for all individuals and therefore has no bearing on increased ED visits. However, little is known about the relationship between quality of life (QoL) and frequency of acute care utilization in this patient population. Methods A cross-sectional study was conducted on 366 patients with SCD who attended the outpatient department at King Fahad Hospital, Hofuf, Saudi Arabia. Data were collected through self-administered surveys, which included: demographics, SCD-related ED visits, clinical issues, and QoL levels. We assessed the ED use by asking for the number of SCD-related ED visits within a 6-month period. Results The self-report survey of ED visits was completed by 308 SCD patients. The median number of SCD-related ED visits within a 6-month time period (IQR) was four (2-7 visits). According to the unadjusted negative binomial model, the rate of SCD-related ED visits increased by (46, 39.3, 40, and 53.5 %) for patients with fever, skin redness with itching, swelling, and blood transfusion, respectively. Poor QoL tends to increase the rate of SCD-related ED visits. Well education and poor general health positively influenced the rate of SCD-related ED visits. Well education tends to increase the rate of SCD-related ED visits by 50.2 %. The rate of SCD-related ED visits decreased by 1.4 % for every point increase in general health. Conclusion Saudi patients with sickle cell disease reported a wide range of SCD-related ED visits. It was estimated that six of 10 SCD patients had at least three ED visits within a 6-month period. Well education and poor general health resulted in an increase in the rate of SCD-related ED visits

    CD1b-restricted GEM T cell responses are modulated by Mycobacterium tuberculosis mycolic acid meromycolate chains

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    Tuberculosis, caused by Mycobacterium tuberculosis, remains a major human pandemic. Germline-encoded mycolyl lipid-reactive (GEM) T cells are donor-unrestricted and recognize CD1b-presented mycobacterial mycolates. However, the molecular requirements governing mycolate antigenicity for the GEM T cell receptor (TCR) remain poorly understood. Here, we demonstrate CD1b expression in tuberculosis granulomas and reveal a central role for meromycolate chains in influencing GEM-TCR activity. Meromycolate fine structure influences T cell responses in TB-exposed individuals, and meromycolate alterations modulate functional responses by GEM-TCRs. Computational simulations suggest that meromycolate chain dynamics regulate mycolate head group movement, thereby modulating GEM-TCR activity. Our findings have significant implications for the design of future vaccines that target GEM T cells

    System effectiveness of a targeted free mass distribution of long lasting insecticidal nets in Zanzibar, Tanzania

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    Insecticide-treated nets (ITN) and long-lasting insecticidal treated nets (LLIN) are important means of malaria prevention. Although there is consensus regarding their importance, there is uncertainty as to which delivery strategies are optimal for dispensing these life saving interventions. A targeted mass distribution of free LLINs to children under five and pregnant women was implemented in Zanzibar between August 2005 and January 2006. The outcomes of this distribution among children under five were evaluated, four to nine months after implementation. Two cross-sectional surveys were conducted in May 2006 in two districts of Zanzibar: Micheweni (MI) on Pemba Island and North A (NA) on Unguja Island. Household interviews were conducted with 509 caretakers of under-five children, who were surveyed for socio-economic status, the net distribution process, perceptions and use of bed nets. Each step in the distribution process was assessed in all children one to five years of age for unconditional and conditional proportion of success. System effectiveness (the accumulated proportion of success) and equity effectiveness were calculated, and predictors for LLIN use were identified. The overall proportion of children under five sleeping under any type of treated net was 83.7% (318/380) in MI and 91.8% (357/389) in NA. The LLIN usage was 56.8% (216/380) in MI and 86.9% (338/389) in NA. Overall system effectiveness was 49% in MI and 87% in NA, and equity was found in the distribution scale-up in NA. In both districts, the predicting factor of a child sleeping under an LLIN was caretakers thinking that LLINs are better than conventional nets (OR = 2.8, p = 0.005 in MI and 2.5, p = 0.041 in NA), in addition to receiving an LLIN (OR = 4.9, p < 0.001 in MI and in OR = 30.1, p = 0.001 in NA). Targeted free mass distribution of LLINs can result in high and equitable bed net coverage among children under five. However, in order to sustain high effective coverage, there is need for complimentary distribution strategies between mass distribution campaigns. Considering the community's preferences prior to a mass distribution and addressing the communities concerns through information, education and communication, may improve the LLIN usage

    FRAX- vs. T-score-based intervention thresholds for osteoporosis

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    Many current guidelines for the assessment of osteoporosis, including those in Kuwait, initiate fracture risk assessment in men and women using BMD T-score thresholds. We compared the Kuwaiti guidelines with FRAX-based age-dependent intervention thresholds equivalent to that in women with a prior fragility fracture. FRAX-based intervention thresholds identified women at higher fracture probability than fixed T-score thresholds, particularly in the elderly. PURPOSE: A FRAX® model been recently calibrated for Kuwait, but guidance is needed on how to utilise fracture probabilities in the assessment and treatment of patients. METHODS: We compared age-specific fracture probabilities, equivalent to women with no clinical risk factors and a prior fragility fracture (without BMD), with the age-specific fracture probabilities associated with femoral neck T-scores of -2.5 and -1.5 SD, in line with current guidelines in Kuwait. Upper and lower assessment thresholds for BMD testing were additionally explored using FRAX. RESULTS: When a BMD T-score of -2.5 SD was used as an intervention threshold, FRAX probabilities of a major osteoporotic fracture in women aged 50 years were approximately twofold higher than those in women of the same age but with an average BMD. The increase in risk associated with the BMD threshold decreased progressively with age such that, at the age of 83 years or more, a T-score of -2.5 SD was associated with a lower probability of fracture than that of the age-matched general population with no clinical risk factors. The same phenomenon was observed from the age of 66 years at a T-score of -1.5 SD. A FRAX-based intervention threshold, defined as the 10-year probability of a major osteoporotic fracture in a woman of average BMI with a previous fracture, rose with age from 4.3% at the age of 50 years to 23%, at the age of 90 years, and identified women at increased risk at all ages. Qualitatively comparable findings were observed in the case of hip fracture probability and in men. CONCLUSION: Intervention thresholds based on BMD alone do not optimally target women at higher fracture risk than those on age-matched individuals without clinical risk factors, particularly in the elderly. In contrast, intervention thresholds based on fracture probabilities equivalent to a 'fracture threshold' consistently target women at higher fracture risk, irrespective of age
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