328 research outputs found

    Moth-inspired navigation algorithm in a turbulent odor plume from a pulsating source

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    Some female moths attract male moths by emitting series of pulses of pheromone filaments propagating downwind. The turbulent nature of the wind creates a complex flow environment, and causes the filaments to propagate in the form of patches with varying concentration distributions. Inspired by moth navigation capabilities, we propose a navigation strategy that enables a flier to locate a pulsating odor source in a windy environment using a single threshold-based detection sensor. The strategy is constructed based on the physical properties of the turbulent flow carrying discrete puffs of odor and does not involve learning, memory, complex decision making or statistical methods. We suggest that in turbulent plumes from a pulsating point source, an instantaneously measurable quantity referred as a "puff crossing time", improves the success rate as compared to the navigation strategy based on "internal counter" that does not use this information. Using computer simulations of fliers navigating in turbulent plumes of the pulsating point source for varying flow parameters: turbulent intensities, plume meandering and wind gusts, we obtained trajectories qualitatively resembling male moths flights towards the pheromone sources. We quantified the probability of a successful navigation as well as the flight parameters such as the time spent searching and the total flight time, with respect to different turbulent intensities, meandering or gusts. The concepts learned using this model may help to design odor-based navigation of miniature airborne autonomous vehicles

    Assessing Challenges Facing Implementation of Information Security Critical Success Factors: A Case of National Examination Council, Tanzania

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    Aim of this study was to assess challenges facing implementation of information security critical success factors. The study employed quantitative research approach and survey research design where case study design was used. A sample of 79 respondents derived from the population sample of 372 were used by using Slovin’s formula sampling technique, 86% of respondents questionnaire filled effectively were used. Descriptive data analysis was used to analyze variables based on research questions while, statistical tables and figures were used in data presentation. Results of this study indicate that, there are challenges in implementation of information security critical success factors such as security training program, security policy, risk assessment, regular system update, system auditing and committed of top management. The study found reasons for challenges of implementation from respondent views as availability of limited resources, weak financial support from top management, lack of understanding of needed technology from information technology professionals; poor security awareness program for top management who may think that information security is the issue of information technology department only and not the whole organization. It is therefore concluded that organization should identify their specific information security critical success factors to enhance useful of organization limited resource, without investing in generalization and give solutions based on risk priority, in order to make organization secure also utilization of information security critical success factors holds significant importance in ensuring security of an organization's data. It is crucial to address and eliminate any challenges that are within the scope of affordability or manageability

    Pre-operational baseline studies of selected nearshore marine biota at the Diablo Canyon power plant site: 1979-1982

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    This is the final report of the California Department of Fish and Games intertidal and subtidal surveys of plants and animals in the vicinity of the Diablo Canyon Power Plant. These studies cover the period from 1979 through 1982. Our previous report (Gotshall, et al. 1984) covered the period from 1973 through 1978. The report includes abundances and statistical analyses of comparisons of abundances between years and study areas for selected intertidal and subtidal plants and animals. A total of 556 random subtidal stations, 540 intertidal stations and 67 permanent abalone transects were completed during this report period. Trends in abundances of most species observed during our 1973 through 1978 studies continued, i.e. the population of giant red sea urchins remained at a very low level, bull kelp Nereocystis leutkeana densities continued to decline in Diablo Cove and North Control. These two trends are probably due to the effects of continued sea otter foraging in the study area. Our observations of the presence or absence of fishes at subtidal 30m stations indicate a continued decline in the abundances of lingcod, Ophiodon elongatus and a decline in the abundance of blue rockfish since the 1973 through 1978 study period. A new study was begun during this study period, the use of baited stations to obtain relative abundance indices for those species of fishes attracted to the bait. Black-and-yellow rockfish were the most frequently observed fishes at Diablo Cove stations, while blue rockfish were the most frequently observed fish at North control baited stations. (Document has 393 pages

    A Comprehensive Overview of In-patients Treated for Hepatocellular Carcinoma at a Tertiary Care Facility in Tanzania

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    Hepatocellular carcinoma (HCC) is one of the commonest causes of cancer-related morbidity and mortality worldwide. However, only a limited number of studies on HCC have been conducted in Tanzania. We therefore conducted a cross-sectional study among in-patients treated for HCC in a tertiary referral hospital located in Dar es Salaam, Tanzania, in order to provide a concise description of the clinical characteristics and treatment options offered in the study setting. We identified 36 in-patients treated for HCC over a 6-month data collection period. Seventy-seven percent (n = 28) of the participants were males and about two-thirds (61.2%) were aged between 40 and 60 years. Majority (44.4% [n = 16]) of the patients had Child-Pugh class B and an Eastern Cooperative Oncology Group (ECOG) performance status of 2 (33.3% [n = 12]). Patients with tumors >6.5 cm and multinodular tumors (>3 nodules) accounted for 69.4% (n = 25) and 55.6% (n = 20), respectively. Portal vascular invasion and extrahepatic metastasis were respectively present in 27.8% (n = 10) and 25% (n = 9) of the patients. Of the study participants, only two had early-stage disease as per the Barcelona Clinic Liver Cancer (BCLC) staging system, corresponding to the observed tumor resection rate of 5.6%. The most frequently reported inoperable factor among the study participants was an ECOG performance status > 0 (n = 30 [83.3%]). Findings thus reveal a high proportion of late-stage diseases among participants that could have resulted in the observed low tumor resection rate. Initiatives to facilitate identification of the disease at an early stage are therefore paramount in optimizing care

    Novel gas-driven fuel cell HVAC and dehumidification prototype

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    Performance of a novel gas-driven, electricity-producing heating, ventilation, and air conditioning (HVAC) system with no vapor compression and no hydrofluorocarbon (HFC) refrigerant shall be discussed in the paper. The prototype was evaluated at ORNL under a Small Business Voucher (SBV) Cooperative Research and Development (CRADA) program. The target market is commercial buildings in the United States. The goal is to mitigate or eliminate grid-power for building air conditioning, coincident peak demand and associated spinning reserves, aiding in flattening of the “duck curve”. The technical goal is to transform the common packaged rooftop unit into a cost-effective distributed energy resource, opening a new range of small applications and broad markets for micro-combined cycle cooling, heating, and power with integral thermal energy storage. The test results indicate the prototype would be competitive with natural gas distributed power plants with average electrical production ranging from 45% to 60% natural gas to electricity conversion efficiency. The technology has a Primary Energy Savings Potential of 4.4 Quads, higher than any other air conditioning and heating technology

    Typology and Dynamics of Heavier Drinking Styles in Great Britain: 1978-2010.

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    AIMS: To identify a typology of heavier drinking styles in Great Britain and to identify socio-demographic trends in the typology over the period 1978-2010. METHODS: We applied multiple correspondence analysis and agglomerative hierarchical clustering to beverage-specific quantity-frequency measures of alcohol consumption in the repeated cross-sectional General Lifestyle Survey of Great Britain, 1978-2010. The cluster analysis focuses on the 60,043 adult respondents over this period reporting average drinking levels above the UK Government guidelines. We projected sex, age, income, education, socio-economic status and tobacco consumption variables onto the clusters to inspect socio-demographic trends in heavier drinking. RESULTS: We identified four stable clusters of heavier drinking: (a) high volume beer; (b) beer and spirit combination; (c) all beverage and (d) wine and spirit only. The socio-demographic characteristics of the clusters were distinct from both each other and the general population. However, all clusters had higher median incomes and higher smoking rates than the population. Increases in the prevalence of heavier drinking were driven by a 5-fold increase in the contribution of the female-dominated, wine and spirit only cluster. CONCLUSIONS: Recent changes in per capita alcohol consumption in Great Britain occurred within the context of a stable typology of heavier drinking styles and shifting socio-demographics. Identifying these trends is essential to better understand how drinking cultures develop over time and where potentially problematic drinking styles may emerge. Our findings suggest that careful attention to patterns and cultures of consumption is more important than relying on headline consumption data, for both understanding drinking behaviours and targeting interventions. SHORT SUMMARY: This analysis of alcohol consumption survey data identifies four styles of heavier drinking in Great Britain, which remain unchanged over the period 1978-2010. The socio-demographic characteristics of the drinking styles are distinct from both each other and the general population, with increased participation of female and older drinkers over time

    Brain function distinguishes female carriers and non-carriers of familial risk for autism

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    BACKGROUND: Autism spectrum disorder (ASD) is characterized by high population-level heritability and a three-to-one male-to-female ratio that occurs independent of sex linkage. Prior research in a mixed-sex pediatric sample identified neural signatures of familial risk elicited by passive viewing of point light motion displays, suggesting the possibility that both resilience and risk of autism might be associated with brain responses to biological motion. To confirm a relationship between these signatures and inherited risk of autism, we tested them in families enriched for genetic loading through undiagnosed ( carrier ) females. METHODS: Using functional magnetic resonance imaging, we examined brain responses to passive viewing of point light displays-depicting biological versus non-biological motion-in a sample of undiagnosed adult females enriched for inherited susceptibility to ASD on the basis of affectation in their respective family pedigrees. Brain responses in carrier females were compared to responses in age-, SRS-, and IQ-matched non-carrier-females-i.e., females unrelated to individuals with ASD. We conducted a hypothesis-driven analysis focused on previously published regions of interest as well as exploratory, brain-wide analyses designed to characterize more fully the rich responses to this paradigm. RESULTS: We observed robust responses to biological motion. Notwithstanding, the 12 regions implicated by prior research did not exhibit the hypothesized interaction between group (carriers vs. controls) and point light displays (biological vs. non-biological motion). Exploratory, brain-wide analyses identified this interaction in three novel regions. Post hoc analyses additionally revealed significant variations in the time course of brain activation in 20 regions spanning occipital and temporal cortex, indicating group differences in response to point light displays (irrespective of the nature of motion) for exploration in future studies. LIMITATIONS: We were unable to successfully eye-track all participants, which prevented us from being able to control for potential differences in eye gaze position. CONCLUSIONS: These methods confirmed pronounced neural signatures that differentiate brain responses to biological and scrambled motion. Our sample of undiagnosed females enriched for family genetic loading enabled discovery of numerous contrasts between carriers and non-carriers of risk of ASD that may index variations in visual attention and motion processing related to genetic susceptibility and inform our understanding of mechanisms incurred by inherited liability for ASD

    COVID-19 Therapeutics for Low- and Middle-Income Countries: A Review of Candidate Agents with Potential for Near-Term Use and Impact.

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    Low- and middle-income countries (LMICs) face significant challenges in the control of COVID-19, given limited resources, especially for inpatient care. In a parallel effort to that for vaccines, the identification of therapeutics that have near-term potential to be available and easily administered is critical. Using the United States (US), European Union (EU), and World Health Organization (WHO) clinical trial registries, we reviewed COVID-19 therapeutic agents currently under investigation. The search was limited to oral or potentially oral agents, with at least a putative anti-SARS-CoV-2 virus mechanism and with at least five registered trials. The search yielded 1,001, 203, and 1,128 trials, in the US, EU, and WHO trial registers, respectively. These trials covered 13 oral or potentially oral repurposed agents that are currently used as antimicrobials and immunomodulatory therapeutics with established safety profiles. The available evidence regarding proposed mechanisms of action, potential limitations, and trial status is summarized. The results of the search demonstrate few published studies of high quality, a low proportion of trials completed, and the vast majority with negative results. These findings reflect limited investment in COVID-19 therapeutics development compared with vaccines. We also identified the need for better coordination of trials of accessible agents and their combinations in LMICs. To prevent COVID-19 from becoming a neglected tropical disease, there is a critical need for rapid and coordinated efforts in the evaluation and deployment of those agents found to be efficacious

    The fitness of African malaria vectors in the presence and limitation of host behaviour

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    <p>Background Host responses are important sources of selection upon the host species range of ectoparasites and phytophagous insects. However little is known about the role of host responses in defining the host species range of malaria vectors. This study aimed to estimate the relative importance of host behaviour to the feeding success and fitness of African malaria vectors, and assess its ability to predict their known host species preferences in nature.</p> <p>Methods Paired evaluations of the feeding success and fitness of African vectors Anopheles arabiensis and Anopheles gambiae s.s in the presence and limitation of host behaviour were conducted in a semi-field system (SFS) at Ifakara Health Institute, Tanzania. In one set of trials, mosquitoes were released within the SFS and allowed to forage overnight on a host that was free to exhibit natural behaviour in response to insect biting. In the other, mosquitoes were allowed to feed directly on from the skin surface of immobile hosts. The feeding success and subsequent fitness of vectors under these conditions were investigated on 6 host types (humans, calves, chickens, cows, dogs and goats) to assess whether physical movements of preferred host species (cattle for An. arabiensis, humans for An. gambiae s.s.) were less effective at preventing mosquito bites than those of common alternatives.</p> <p>Results Anopheles arabiensis generally had greater feeding success when applied directly to host skin than when foraging on unrestricted hosts (in five of six host species). However, An. gambiae s.s obtained blood meals from free and restrained hosts with similar success from most host types (four out of six). Overall, the blood meal size, oviposition rate, fecundity and post-feeding survival of mosquito vectors were significantly higher after feeding on hosts free to exhibit behaviour, than those who were immobilized during feeding trials.</p> <p>Conclusions Allowing hosts to move freely during exposure to mosquitoes was associated with moderate reductions in mosquito feeding success, but no detrimental impact to the subsequent fitness of mosquitoes that were able to feed upon them. This suggests that physical defensive behaviours exhibited by common host species including humans do not impose substantial fitness costs on African malaria vectors.</p&gt
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