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The architectural complexity of flower structures (hereafter referred to as floral complexity) may be linked to pollination by specialized pollinators that can increase the probability of successful seed set. As plant—pollinator systems become fragile, a loss of such specialized pollinators could presumably result in an increased likelihood of pollination failure. This is an issue likely to be particularly evident in plants that are currently rare. Using a novel index describing floral complexity we explored whether this aspect of the structure of flowers could be used to predict vulnerability of plant species to extinction. To do this we defined plant vulnerability using the Red Data Book of Rare and Threatened Plants of Greece, a Mediterranean biodiversity hotspot. We also tested whether other intrinsic (e.g. life form, asexual reproduction) or extrinsic (e.g. habitat, altitude, range-restrictedness) factors could affect plant vulnerability. We found that plants with high floral complexity scores were significantly more likely to be vulnerable to extinction. Among all the floral complexity components only floral symmetry was found to have a significant effect, with radial-flower plants appearing to be less vulnerable. Life form was also a predictor of vulnerability, with woody perennial plants having significantly lower risk of extinction. Among the extrinsic factors, both habitat and maximum range were significantly associated with plant vulnerability (coastal plants and narrow-ranged plants are more likely to face higher risk). Although extrinsic and in particular anthropogenic factors determine plant extinction risk, intrinsic traits can indicate a plant’s proneness to vulnerability. This raises the potential threat of declining global pollinator diversity interacting with floral complexity to increase the vulnerability of individual plant species. There is potential scope for using plant—pollinator specializations to identify plant species particularly at risk and so target conservation efforts towards them.  相似文献   

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Linked social-ecological systems in which surprise and crisis are interspersed with periods of stability and predictability are inherently difficult to manage. This condition, coupled with the legacies of past management actions, typically leaves policy and decision makers few options other than to incrementally adapt and reinforce the current trajectory of the system. Decision making becomes increasingly reactive and incremental as the system moves from one crisis to another. Eventually the system loses its capacity to cope with perturbations and surprise. Using a combination of dynamical-systems modeling and historical analysis, we studied a process of this kind as it developed in the Goulburn Broken Catchment in southeastern Australia over the past 150 years. Using the model to simulate trajectories of the biohydrological system, we correlate the state of the physical system to historical events and management action. We show how sequential management decisions have eroded the resilience of the system (its ability to cope with shocks and surprises) and reduced options for future change. Using the model in a forward-looking mode, we explore future management options and their implications for the resilience of the system.  相似文献   

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There is evidence that HIV prevention programs for sex workers, especially female sex workers, are cost-effective in several contexts, including many western countries, Thailand, India, the Democratic Republic of Congo, Kenya, and Zimbabwe. The evidence that sex worker HIV prevention programs work must not inspire complacency but rather a renewed effort to expand, intensify, and maximize their impact. The PLOS Collection “Focus on Delivery and Scale: Achieving HIV Impact with Sex Workers” highlights major challenges to scaling-up sex worker HIV prevention programs, noting the following: sex worker HIV prevention programs are insufficiently guided by understanding of epidemic transmission dynamics, situation analyses, and programmatic mapping; sex worker HIV and sexually transmitted infection services receive limited domestic financing in many countries; many sex worker HIV prevention programs are inadequately codified to ensure consistency and quality; and many sex worker HIV prevention programs have not evolved adequately to address informal sex workers, male and transgender sex workers, and mobile- and internet-based sex workers. Based on the wider collection of papers, this article presents three major clusters of recommendations: (i) HIV programs focused on sex workers should be prioritized, developed, and implemented based on robust evidence; (ii) national political will and increased funding are needed to increase coverage of effective sex worker HIV prevention programs in low and middle income countries; and (iii) comprehensive, integrated, and rapidly evolving HIV programs are needed to ensure equitable access to health services for individuals involved in all forms of sex work.

Summary Points

  • HIV prevention programs for sex workers, especially female sex workers, are cost-effective.
  • There are opportunities to further increase the impact of HIV prevention programs for sex workers and to adapt interventions to a changing context.
  • Many sex worker HIV prevention programs are insufficiently guided by understanding of epidemic transmission dynamics, situation analyses, and programmatic mapping; receive limited domestic financing in many countries; are inadequately codified to ensure consistency and quality; and have not evolved adequately to address informal sex workers, male and transgender sex workers, and mobile and internet-based sex workers.
  • We recommend increasing our understanding of HIV epidemic transmission dynamics, improving situation analyses and programmatic mapping, increasing domestic financing for sex worker HIV prevention programs where feasible, delivering well-codified, comprehensive programs using “Science of Delivery” principles and developing more effective models to reach informal sex workers, male and transgender sex workers, and mobile and internet-based sex workers.
  • Given their marginalization, concerted efforts must be made to ensure sex workers have equitable access to HIV prevention, care, and treatment services, as well as wider health services, particularly for STIs, mental health, and addictions.
  相似文献   

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The detection of patterns in monitoring data of vital signs is of great importance for adequate bedside decision support in critical care. Currently used alarm systems, which are based on fixed thresholds and independency assumptions, are not satisfactory in clinical practice. Time series techniques such as AR‐models consider autocorrelations within the series, which can be used for pattern recognition in the data. For practical applications in intensive care the data analysis has to be automated. An important issue is the suitable choice of the model order which is difficult to accomplish online. In a comparative case‐study we analyzed 34564 univariate time series of hemodynamic variables in critically ill patients by autoregressive models of different orders and compared the results of pattern detection. AR(2)‐models seem to be most suitable for the detection of clinically relevant patterns, thus affirming that treating the data as independent leads to false alarms. Moreover, using AR(2)‐models affords only short estimation periods. These findings for pattern detection in intensive care data are of medical importance as they justify a preselection of a model order, easing further automated statistical online analysis.  相似文献   

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It is often argued that the benefit of eradication of an invasive species—a one-off injection of funds and the problem is solved—far outweighs the cost of a perennial control program. Furthermore, these are very attractive projects for funding agencies as outcomes are clear and easy to assess. Galapagos is in the early stage of the invasion process, with most alien species not yet naturalized and still restricted to gardens and farms. These species should be easy targets for early and cost-effective eradication projects, which would prevent many future problems. We review 30 plant eradication projects covering 23 potentially invasive species with limited distributions on four of the Galapagos Islands. Of the 30 projects, only four were successful: these were all less than 1 ha in net area, on land with a single owner and did not have persistent seed banks. Of the other 26 projects, most failed due to a lack of support from institutions that did not offer continuity of resources, from land owners who denied permission to carry out the work or from being too ambitious. As a result of these problems, 64.3% of the funding secured for the program was spent on discontinued projects. We highlight lessons learned to inform plant eradication programs in the future.  相似文献   

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Asclepias fruticosa L. is a small shrub containing latex with proteolytic activity. The crude extract (latex diluted 1:250 and ultracentrifuged) contained 276 g of protein/mL and the proteolytic activity reached 1.2 caseinolytic U/mL. This enzyme preparation was very stable even after 2 hours at 45°C, but was quickly inactivated after 5 minutes at 80°C. Chromatographic purification was achieved by FPLC using a cation exchanger (SP-Sepharose FF). Thus, a unique proteolitically active fraction could be isolated, being homogeneous by bidimensional electrophoresis and mass spectrometry (Mr = 23,652). The optimum pH range was achieved at 8.5–10.5. The enzyme activity was completely inhibited by specific cysteine peptidases inhibitors. Isoelectric focusing followed by zymogram showed the enzyme had a pI greater than 9.3. The N-terminus sequence (LPDSVDWREKGVVFPIRNQGK) shows a great deal of similarity to those of the other cysteine endopeptidases isolated from latices of Asclepiadaceae even when a high degree of homology could be observed with other plant cysteine endopeptidases.  相似文献   

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Response and effect traits help to understand how changes in ecological communities (e.g. in response to land use) relate to changes in ecosystem functioning. In grasslands, plants and insect herbivores are involved in many ecosystem processes such as herbivory and plant biomass production. Simultaneous changes in the trait composition of both plants and herbivores should affect herbivory rates, with consequences for plant growth and potentially biomass production. The mechanisms underlying these links are little understood for grasses and sucking insects, which build a major part of grassland communities. In a mesocosm experiment, we manipulated the composition of grasses and sucking herbivores (Hemiptera) to study the role of plant traits, herbivore traits and their interaction on herbivory and plant growth. Because sucking herbivory is generally difficult to quantify, we developed a novel experimental setting, in which we labelled plants with 15N isotope. This allowed to quantify 15N uptake and thus sucking rates of individuals. We found that herbivory and simultaneous plant growth reduction are most strongly linked to herbivore species identity. Unexpectedly, herbivory did not increase with herbivore size, but was highest for small species and for thin-bodied Heteroptera. Additionally, herbivory and plant growth reduction depended on the interacting herbivore and plant species, indicating trait matching, which could, however, not be explained with commonly used traits. This indicates that mechanisms linking ecological communities and ecosystem processes are highly context-specific. To understand how global change affects ecosystem functioning, studies need to cover all functionally relevant groups, including plant sap suckers.  相似文献   

10.
It has been more than 35 years since the last naturally occurring case of smallpox. Sufficient time has passed to allow an objective overview of what were the key factors in the success of the eradication effort and what lessons smallpox can offer to other campaigns. Professor D. A. Henderson headed the international effort to eradicate smallpox. Here, we present a summary of D. A. Henderson''s perspectives on the eradication of smallpox. This text is based upon the Unither Baruch Blumberg Lecture, delivered by D. A. Henderson at the University of Oxford in November 2012 and upon conversations and correspondence with Professor Henderson.  相似文献   

11.
Microsatellites are powerful markers often isolated de novo for species yet to be investigated. Enriched genomic libraries are usually used for isolation purposes. We critically evaluate the outcome of an enrichment-based protocol applied to two insect species (the ant Lasius austriacus and the beetle Pityogenes chalcographus) which yielded contrasting numbers of suitable loci. Our findings of differences in microsatellite isolation are consistent with the available data on differences in genomic characteristics across these taxa. In the beetle repeated isolation of identical motifs, difficulties in primer development, and multibanded products caused loss of most candidate clones. We identified critical steps during marker development. Reviewing Editor: Dr. John Oakeshott  相似文献   

12.
Restoring disturbed lands is essential for conserving biodiversity. In floristically diverse regions, restoring all plant species following anthropogenic disturbance is financially costly and it is unknown if this can be achieved. However, re‐creating faunal habitat may not require reinstating all plant species if there is a high degree of redundancy. Here, we assess whether there is redundancy among a subset of native plant species chosen to restore fauna habitat following a severe disturbance. Additionally, we determine if reestablished plants support similar faunal assemblages as the same plant species in less disturbed forest. We sampled plant‐dwelling Hemiptera from 1,800 plants across 16 species. We found 190 species of Hemiptera, with most plant species in the forest having distinct hemipteran assemblages. Returning these plant species to areas undergoing restoration reinstated 145 hemipteran species, including the dominant species. Recalcitrant plant species (difficult to propagate and reestablish in restored areas) had different hemipteran assemblages from all other species. There was only one plant species that did not have a distinct assemblage and thus was considered redundant. We conclude that there is little redundancy in this study. For plant‐dwelling Hemiptera (with good powers of dispersal) to recolonize restored areas, restoration efforts will need to reinstate at least 13 of the 16 species of host plant of appropriate age and structure. Consequently, to meet the goal of restoring fauna habitat when there is no knowledge of which plant species are redundant, restoration projects should aim to reinstate all plant species present in less disturbed reference areas.  相似文献   

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Nigeria is the most populous country in Africa, has a large proportion of the world''s poor livestock keepers, and is a hotspot for neglected zoonoses. A review of the 127 accessible publications on brucellosis in Nigeria reveals only scant and fragmented evidence on its spatial and temporal distribution in different epidemiological contexts. The few bacteriological studies conducted demonstrate the existence of Brucella abortus in cattle and sheep, but evidence for B. melitensis in small ruminants is dated and unclear. The bulk of the evidence consists of seroprevalence studies, but test standardization and validation are not always adequately described, and misinterpretations exist with regard to sensitivity and/or specificity and ability to identify the infecting Brucella species. Despite this, early studies suggest that although brucellosis was endemic in extensive nomadic systems, seroprevalence was low, and brucellosis was not perceived as a real burden; recent studies, however, may reflect a changing trend. Concerning human brucellosis, no studies have identified the Brucella species and most reports provide only serological evidence of contact with Brucella in the classical risk groups; some suggest brucellosis misdiagnoses as malaria or other febrile conditions. The investigation of a severe outbreak that occurred in the late 1970s describes the emergence of animal and human disease caused by the settling of previously nomadic populations during the Sahelian drought. There appears to be an increasing risk of re-emergence of brucellosis in sub-Saharan Africa, as a result of the co-existence of pastoralist movements and the increase of intensive management resulting from growing urbanization and food demand. Highly contagious zoonoses like brucellosis pose a threat with far-reaching social and political consequences.  相似文献   

17.
The best-known attribute of the prion protein (PrP) is its tendency to misfold into a rogue isoform. Much less understood is how this misfolded isoform causes deadly brain illnesses. Neurodegeneration in prion disease is often seen as a consequence of abnormal PrP function yet, amazingly little is known about the normal, physiological role of PrP. In particular, the absence of obvious phenotypes in PrP knockout mice has prevented scientists from answering this important question. Using knockdown approaches, we previously produced clear PrP loss-of-function phenotypes in zebrafish embryos. Analysis of these phenotypes revealed that PrP can modulate E-cadherin-based cell-cell adhesion, thereby controlling essential morphogenetic cell movements in the early gastrula. Our data also showed that PrP itself can elicit homophilic cell-cell adhesion and trigger intracellular signaling via Src-related kinases. Importantly, these molecular functions of PrP are conserved from fish to mammals. Here we discuss the use of the zebrafish in prion biology and how it may advance our understanding of the roles of PrP in health and disease.Key words: PrP, zebrafish, development, cell adhesion, signaling  相似文献   

18.
Voluntary medical male circumcision (VMMC) is capable of reducing the risk of sexual transmission of HIV from females to males by approximately 60%. In 2007, the WHO and the Joint United Nations Programme on HIV/AIDS (UNAIDS) recommended making VMMC part of a comprehensive HIV prevention package in countries with a generalized HIV epidemic and low rates of male circumcision. Modeling studies undertaken in 2009–2011 estimated that circumcising 80% of adult males in 14 priority countries in Eastern and Southern Africa within five years, and sustaining coverage levels thereafter, could avert 3.4 million HIV infections within 15 years and save US$16.5 billion in treatment costs. In response, WHO/UNAIDS launched the Joint Strategic Action Framework for accelerating the scale-up of VMMC for HIV prevention in Southern and Eastern Africa, calling for 80% coverage of adult male circumcision by 2016. While VMMC programs have grown dramatically since inception, they appear unlikely to reach this goal. This review provides an overview of findings from the PLOS Collection “Voluntary Medical Male Circumcision for HIV Prevention: Improving Quality, Efficiency, Cost Effectiveness, and Demand for Services during an Accelerated Scale-up.” The use of devices for VMMC is also explored. We propose emphasizing management solutions to help VMMC programs in the priority countries achieve the desired impact of averting the greatest possible number of HIV infections. Our recommendations include advocating for prioritization and funding of VMMC, increasing strategic targeting to achieve the goal of reducing HIV incidence, focusing on programmatic efficiency, exploring the role of new technologies, rethinking demand creation, strengthening data use for decision-making, improving governments'' program management capacity, strategizing for sustainability, and maintaining a flexible scale-up strategy informed by a strong monitoring, learning, and evaluation platform.

Summary Points

  • Large-scale implementation of voluntary medical male circumcision (VMMC) in 14 priority countries of Eastern and Southern Africa has the potential to significantly reduce heterosexual transmission of HIV to males, saving lives, averting suffering, and avoiding health care costs.
  • Resource and capacity constraints pose a serious challenge to the ability of the priority countries to reach their goals for VMMC scale-up.
  • The 13 papers in this collection examine issues of service quality, demand creation, cost, and efficiency faced by governments, donors, and programs.
  • Systematic, evidence-based management of programs and a dynamic culture of learning are proposed to help meet the challenges of VMMC scale-up.
  • Recommendations include greater prioritization and funding of VMMC, strategic targeting and demand creation, a focus on programmatic efficiencies, and exploration of new technologies.
  • Further recommendations are for strengthened data use, improving governments'' program management capacity, strategizing for sustainability, and maintaining a flexible scale-up strategy.
  相似文献   

19.
Recent publications have established the pulse oxygen saturation (SpO2) threshold of 90% for the hospitalization and discharge of infant patients with bronchiolitis. However, there is no clear recommendation regarding the Emergency Department (ED) observation period necessary before allowing safe home discharge for patients with SpO2 above 90%-92%. Our primary aims were to evaluate the risk factors associated with delayed desaturation in infants with SpO2 ≥ 92% on arrival at the ED as well as the ED observation period necessary before allowing safe home discharge. A secondary aim was to identify the risk factors for ED readmission. Of 581 episodes of bronchiolitis in patients < 1 year old admitted to the ED, only 47 (8%) had SpO2 < 92% on arrival there, although 106 (18%) exhibited a delayed desaturation (to < 92%) during ED observation. Female sex, age < 3 months old, ED readmission, more severe initial clinical presentation, and higher pCO2 level (> 6KPa) were risk factors for delayed desaturation with OR varying from 1.7 to 7.5. In patients < 3 months old, mean desaturation occured later than in older patients [6.0 hours (IQR 3.0–14.0) vs. 3.0 hours (IQR 2.0–6.0), P = 0.0018]. In 95% of patients with a delayed desaturation this decrease occurred within 25 hours for patients < 3 months old and within 11 hours for patients ≥ 3 months old. In patients < 3 months old with respiratory rates above the normal range for their age the desaturation occurred earlier than in patients < 3 months with normal respiratory rates [4.4 hours (IQR 3.0–11.7) vs. 14.6 hours (IQR 7.6–22.2), P = 0.037]. Based on the present study’s results, we propose a five step guide for pediatricians on discharging children with bronchiolitis from the ED. By using the threshold of an 11 hour ED observation period for patients ≥ 3 months old and a 25 hour period for patients < 3 months old we are able to detect 95% of the patients with bronchiolitis who are at risk of delayed desaturation.  相似文献   

20.

Background

Early diagnosis of HIV and treatment initiation at higher CD4 counts improves outcomes and reduces transmission. However, Lesotho is not realizing the full benefits of ART because of the low proportion of men tested (40%). Public sector VMMC services, which were launched in district hospitals in February 2012 by the Lesotho MOH supported by USAID/MCHIP, include HIV testing with referral to care and treatment. The objective of this study was to better understand the contribution of VMMC services to HIV diagnosis and treatment.

Methods

VMMC clients diagnosed with HIV were traced after 6 months to ascertain whether they: (1) presented to the referral HIV center, (2) had a CD4 count done and (3) were enrolled on ART. Linkages between VMMC and HIV services were assessed by comparing the proportion of HIV-infected males referred from VMMC services with those from other hospital departments.

Results

Between March and September 2012, 72 men presenting for VMMC services tested positive for HIV, representing 65% of the total male tests at the hospital; 45 of these men (62.5%) received an immediate CD4 count and went to the HIV referral site; 40 (89%) were eligible for treatment and initiated ART. 27 clients did not have a CD4 count due to stock-out of reagents. Individuals who did not receive a CD4 count on the same day did not return to the HIV center.

Conclusion

All VMMC clients testing positive for HIV and receiving a CD4 count on the testing day began ART. Providing VMMC services in a district hospital offering the continuum of care could increase diagnoses and treatment uptake among men, but requires an investment in communication between VMMC and ART clinics. In high HIV prevalence settings, investing in PIMA CD4 devices at integrated VMMC clinics is likely to increase male ART enrolment.  相似文献   

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