GNBP domain of Anopheles darlingi: are polymorphic inversions and gene variation related to adaptive evolution?

PubMed

Bridi, L C; Rafael, M S

2016-02-01

Anopheles darlingi is the main malaria vector in humans in South America. In the Amazon basin, it lives along the banks of rivers and lakes, which responds to the annual hydrological cycle (dry season and rainy season). In these breeding sites, the larvae of this mosquito feed on decomposing organic and microorganisms, which can be pathogenic and trigger the activation of innate immune system pathways, such as proteins Gram-negative binding protein (GNBP). Such environmental changes affect the occurrence of polymorphic inversions especially at the heterozygote frequency, which confer adaptative advantage compared to homozygous inversions. We mapped the GNBP probe to the An. darlingi 2Rd inversion by fluorescent in situ hybridization (FISH), which was a good indicator of the GNBP immune response related to the chromosomal polymorphic inversions and adaptative evolution. To better understand the evolutionary relations and time of divergence of the GNBP of An. darlingi, we compared it with nine other mosquito GNBPs. The results of the phylogenetic analysis of the GNBP sequence between the species of mosquitoes demonstrated three clades. Clade I and II included the GNBPB5 sequence, and clade III the sequence of GNBPB1. Most of these sequences of GNBP analyzed were homologous with that of subfamily B, including that of An. gambiae (87 %), therefore suggesting that GNBP of An. darling belongs to subfamily B. This work helps us understand the role of inversion polymorphism in evolution of An. darlingi.

Chromosomal localization of actin genes in the malaria mosquito Anopheles darlingi

PubMed Central

BRIDI, L. C.; SHARAKHOVA, M. V.; SHARAKHOV, I. V.; CORDEIRO, J.; AZEVEDO, G. M.; TADEI, W. P.; RAFAEL, M. S.

2012-01-01

Physical and genetic maps have been used for chromosomal localization of genes in vectors of infectious diseases. The availability of polytene chromosomes in malaria mosquitoes provides a unique opportunity to precisely map genes of interest. We report physical mapping of two actin genes on polytene chromosomes of the major malaria vector in Amazon Anopheles darlingi. The clones with the actin genes sequences were obtained from a cDNA library constructed from RNA isolated from adult females and males of An. darlingi. Each of the two clones was mapped to a unique site on the chromosomal arm 2L in subdivisions 21A (clone pl05-A04) and 23B (clone pl17-G06). The obtained results together with previous mapping data provide a suitable basis for comparative genomics and for establishing chromosomal homologies among major malaria vectors. PMID:22804344

Anopheles darlingi (Diptera: Culicidae) displays increased attractiveness to infected individuals with Plasmodium vivax gametocytes.

PubMed

Batista, Elis Pa; Costa, Elizangela Fm; Silva, Alexandre A

2014-05-29

Most hematophagous insects use host odours as chemical cues. The odour components, some physiological parameters and host attractiveness are affected by several conditions, including infection by parasites, e.g., plasmodia and, therefore, change the epidemiological scenario. This study evaluated the attractiveness of individuals with vivax malaria before, during (7 days) and after treatment (14 days) with specific antimalarial drugs. Mosquito attractiveness to vivax-infected patients was assessed using a vertical olfactometer using the foot as a source of body odour. The ratio of Anopheles darlingi mosquitoes in the lower chamber of the olfactometer was used to calculate the attractiveness, and patient temperature was measured using a digital thermometer. An increased attractiveness was found only in patients bearing vivax gametocytes during the first experiment (early infection) (P<0.001). Patients in the first experiment tended to have a higher body temperature, but grouping patients into fever and non-fever resulted in a higher attractiveness only in the fever group of gametocyte carriers, suggesting a synergistic effect of temperature and gametocytes in the host attractiveness to A. darlingi. Gametocyte presence and fever in vivax malaria patients increased short distance host attractiveness to An. darlingi.

Habitat suitability mapping of Anopheles darlingi in the surroundings of the Manso hydropower plant reservoir, Mato Grosso, Central Brazil.

PubMed

Zeilhofer, Peter; dos Santos, Emerson Soares; Ribeiro, Ana L M; Miyazaki, Rosina D; dos Santos, Marina Atanaka

2007-03-07

Hydropower plants provide more than 78 % of Brazil's electricity generation, but the country's reservoirs are potential new habitats for main vectors of malaria. In a case study in the surroundings of the Manso hydropower plant in Mato Grosso state, Central Brazil, habitat suitability of Anopheles darlingi was studied. Habitat profile was characterized by collecting environmental data. Remote sensing and GIS techniques were applied to extract additional spatial layers of land use, distance maps, and relief characteristics for spatial model building. Logistic regression analysis and ROC curves indicate significant relationships between the environment and presence of An. darlingi. Probabilities of presence strongly vary as a function of land cover and distance from the lake shoreline. Vector presence was associated with spatial proximity to reservoir and semi-deciduous forests followed by Cerrado woodland. Vector absence was associated with open vegetation formations such as grasslands and agricultural areas. We suppose that non-significant differences of vector incidences between rainy and dry seasons are associated with the availability of anthropogenic breeding habitat of the reservoir throughout the year. Satellite image classification and multitemporal shoreline simulations through DEM-based GIS-analyses consist in a valuable tool for spatial modeling of A. darlingi habitats in the studied hydropower reservoir area. Vector presence is significantly increased in forested areas near reservoirs in bays protected from wind and wave action. Construction of new reservoirs under the tropical, sub-humid climatic conditions should therefore be accompanied by entomologic studies to predict the risk of malaria epidemics.

Population dynamics, structure and behavior of Anopheles darlingi in a rural settlement in the Amazon rainforest of Acre, Brazil.

PubMed

Moutinho, Paulo Rufalco; Gil, Luis Herman Soares; Cruz, Rafael Bastos; Ribolla, Paulo Eduardo Martins

2011-06-24

Anopheles darlingi is the major vector of malaria in South America, and its behavior and distribution has epidemiological importance to biomedical research. In Brazil, An. darlingi is found in the northern area of the Amazon basin, where 99.5% of the disease is reported. The study area, known as Ramal do Granada, is a rural settlement inside the Amazon basin in the state of Acre. Population variations and density have been analysed by species behaviour, and molecular analysis has been measured by ND4 mitochondrial gene sequencing. The results show higher density in collections near a recent settlement, suggesting that a high level of colonization decreases the vector presence. The biting activity showed higher activity at twilight and major numbers of mosquitos in the remaining hours of the night in months of high density. From a sample of 110 individual mosquitoes, 18 different haplotypes were presented with a diversity index of 0.895, which is higher than that found in other Anopheles studies. An. darlingi depends on forested regions for their larval and adult survival. In months with higher population density, the presence of mosquitoes persisted in the second part of the night, increasing the vector capacity of the species. Despite the intra-population variation in the transition to rainy season, the seasonal distribution of haplotypes shows no change in the structure population of An. darlingi.

Habitat suitability mapping of Anopheles darlingi in the surroundings of the Manso hydropower plant reservoir, Mato Grosso, Central Brazil

PubMed Central

Zeilhofer, Peter; Santos, Emerson Soares dos; Ribeiro, Ana LM; Miyazaki, Rosina D; Santos, Marina Atanaka dos

2007-01-01

Background Hydropower plants provide more than 78 % of Brazil's electricity generation, but the country's reservoirs are potential new habitats for main vectors of malaria. In a case study in the surroundings of the Manso hydropower plant in Mato Grosso state, Central Brazil, habitat suitability of Anopheles darlingi was studied. Habitat profile was characterized by collecting environmental data. Remote sensing and GIS techniques were applied to extract additional spatial layers of land use, distance maps, and relief characteristics for spatial model building. Results Logistic regression analysis and ROC curves indicate significant relationships between the environment and presence of An. darlingi. Probabilities of presence strongly vary as a function of land cover and distance from the lake shoreline. Vector presence was associated with spatial proximity to reservoir and semi-deciduous forests followed by Cerrado woodland. Vector absence was associated with open vegetation formations such as grasslands and agricultural areas. We suppose that non-significant differences of vector incidences between rainy and dry seasons are associated with the availability of anthropogenic breeding habitat of the reservoir throughout the year. Conclusion Satellite image classification and multitemporal shoreline simulations through DEM-based GIS-analyses consist in a valuable tool for spatial modeling of A. darlingi habitats in the studied hydropower reservoir area. Vector presence is significantly increased in forested areas near reservoirs in bays protected from wind and wave action. Construction of new reservoirs under the tropical, sub-humid climatic conditions should therefore be accompanied by entomologic studies to predict the risk of malaria epidemics. PMID:17343728

Population dynamics, structure and behavior of Anopheles darlingi in a rural settlement in the Amazon rainforest of Acre, Brazil

PubMed Central

2011-01-01

Background Anopheles darlingi is the major vector of malaria in South America, and its behavior and distribution has epidemiological importance to biomedical research. In Brazil, An. darlingi is found in the northern area of the Amazon basin, where 99.5% of the disease is reported. Methods The study area, known as Ramal do Granada, is a rural settlement inside the Amazon basin in the state of Acre. Population variations and density have been analysed by species behaviour, and molecular analysis has been measured by ND4 mitochondrial gene sequencing. Results The results show higher density in collections near a recent settlement, suggesting that a high level of colonization decreases the vector presence. The biting activity showed higher activity at twilight and major numbers of mosquitos in the remaining hours of the night in months of high density. From a sample of 110 individual mosquitoes, 18 different haplotypes were presented with a diversity index of 0.895, which is higher than that found in other Anopheles studies. Conclusions An. darlingi depends on forested regions for their larval and adult survival. In months with higher population density, the presence of mosquitoes persisted in the second part of the night, increasing the vector capacity of the species. Despite the intra-population variation in the transition to rainy season, the seasonal distribution of haplotypes shows no change in the structure population of An. darlingi. PMID:21702964

Insecticidal activity of Leptodactylus knudseni and Phyllomedusa vaillantii crude skin secretions against the mosquitoes Anopheles darlingi and Aedes aegypti

PubMed Central

2014-01-01

Background Mosquitoes are important vectors of several diseases, including malaria and dengue, and control measures are mostly performed using chemical insecticides. Unfortunately, mosquito resistance to commonly applied insecticides is widespread. Therefore, a prospection for new molecules with insecticidal activity based on Amazon biodiversity using the anurans Leptodactylus knudseni and Phyllomedusa vaillantii was performed against the mosquito species Anopheles darlingi and Aedes aegypti. Methods The granular secretion from anuran skin was obtained by manual stimulation, and lethal concentrations (LCs) for larvicidal and adulticidal tests were calculated using concentrations from 1-100 ppm. The skin secretions from the anuran species tested caused significant mortality within the first 24 hours on adults and larvae, but differed within the mosquito species. Results The skin secretions from the anuran species tested caused significant mortality within the first 24 hours on adults and larvae, but differed within the mosquito species. The calculated LC50 of L. knudseni skin secretions against An. darlingi was 0.15 and 0.2 ppm for adults and larvae, respectively, but much higher for Ae. aegypti, i.e., 19 and 38 ppm, respectively. Interestingly, the calculated LCs50 of P. vaillantii against both mosquito species in adults were similar, 1.8 and 2.1 ppm, respectively, but the LC50 for An. darlingi larvae was much lower (0.4 ppm) than for Ae aegypti (2.1 ppm). Conclusions The present experiments indicate that skin secretions from L. knudseni and P. vaillantii contain bioactive molecules with potent insecticide activity. The isolation and characterization of skin secretions components will provide new insights for potential insecticidal molecules. PMID:25165469

Is there an efficient trap or collection method for sampling Anopheles darlingi and other malaria vectors that can describe the essential parameters affecting transmission dynamics as effectively as human landing catches? - A Review

PubMed Central

Lima, José Bento Pereira; Rosa-Freitas, Maria Goreti; Rodovalho, Cynara Melo; Santos, Fátima; Lourenço-de-Oliveira, Ricardo

2014-01-01

Distribution, abundance, feeding behaviour, host preference, parity status and human-biting and infection rates are among the medical entomological parameters evaluated when determining the vector capacity of mosquito species. To evaluate these parameters, mosquitoes must be collected using an appropriate method. Malaria is primarily transmitted by anthropophilic and synanthropic anophelines. Thus, collection methods must result in the identification of the anthropophilic species and efficiently evaluate the parameters involved in malaria transmission dynamics. Consequently, human landing catches would be the most appropriate method if not for their inherent risk. The choice of alternative anopheline collection methods, such as traps, must consider their effectiveness in reproducing the efficiency of human attraction. Collection methods lure mosquitoes by using a mixture of olfactory, visual and thermal cues. Here, we reviewed, classified and compared the efficiency of anopheline collection methods, with an emphasis on Neotropical anthropophilic species, especially Anopheles darlingi, in distinct malaria epidemiological conditions in Brazil. PMID:25185008

Larval food quantity affects development time, survival and adult biological traits that influence the vectorial capacity of Anopheles darlingi under laboratory conditions.

PubMed

Araújo, Maisa da-Silva; Gil, Luiz Herman S; e-Silva, Alexandre de-Almeida

2012-08-02

The incidence of malaria in the Amazon is seasonal and mosquito vectorial capacity parameters, including abundance and longevity, depend on quantitative and qualitative aspects of the larval diet. Anopheles darlingi is a major malaria vector in the Amazon, representing >95% of total Anopheles population present in the Porto Velho region. Despite its importance in the transmission of the Plasmodium parasite, knowledge of the larval biology and ecology is limited. Studies regarding aspects of adult population ecology are more common than studies on larval ecology. However, in order develop effective control strategies and laboratory breeding conditions for this species, more data on the factors affecting vector biology is needed. The aim of the present study is to assess the effects of larval food quantity on the vectorial capacity of An. darling under laboratory conditions. Anopheles darlingi was maintained at 28°C, 80% humidity and exposed to a daily photoperiod of 12 h. Larvae were divided into three experimental groups that were fed either a low, medium, or high food supply (based on the food amounts consumed by other species of culicids). Each experiment was replicated for six times. A cohort of adults were also exposed to each type of diet and assessed for several biological characteristics (e.g. longevity, bite frequency and survivorship), which were used to estimate the vectorial capacity of each experimental group. The group supplied with higher food amounts observed a reduction in development time while larval survival increased. In addition to enhanced longevity, increasing larval food quantity was positively correlated with increasing frequency of bites, longer blood meal duration and wing length, resulting in greater vectorial capacity. However, females had greater longevity than males despite having smaller wings. Overall, several larval and adult biological traits were significantly affected by larval food availability. Greater larval food supply

Development of the BG-Malaria trap as an alternative to human-landing catches for the capture of Anopheles darlingi

PubMed Central

Gama, Renata Antonaci; da Silva, Ivoneide Maria; Geier, Martin; Eiras, Álvaro Eduardo

2013-01-01

Although the human-landing catch (HLC) method is the most effective for collecting anthropophilic anophelines, it has been increasingly abandoned, primarily for ethical considerations. The objective of the present study was to develop a new trap for the collection of Anopheles darlingi . The initial trials were conducted using the BG-Sentinel trap as a standard for further trap development based on colour, airflow direction and illumination. The performance of the trap was then compared with those of the CDC, Fay-Prince, counterflow geometry trap (CFG) and HLC. All trials were conducted outdoors between 06:00 pm-08:00 pm. Female specimens of An. darlingi were dissected to determine their parity. A total of 8,334 anophelines were captured, of which 4,945 were identified as An. darlingi . The best trap configuration was an all-white version, with an upward airflow and no required light source. This configuration was subsequently named BG-Malaria (BGM). The BGM captured significantly more anophelines than any of the other traps tested and was similar to HLC with respect to the number and parity of anophelines. The BGM trap can be used as an alternative to HLC for collecting anophelines. PMID:24037199

Anopheles darlingi polytene chromosomes: revised maps including newly described inversions and evidence for population structure in Manaus

PubMed Central

Cornel, Anthony J; Brisco, Katherine K; Tadei, Wanderli P; Secundino, Nágila FC; Rafael, Miriam S; Galardo, Allan KR; Medeiros, Jansen F; Pessoa, Felipe AC; Ríos-Velásquez, Claudia M; Lee, Yoosook; Pimenta, Paulo FP; Lanzaro, Gregory C

2016-01-01

Salivary gland polytene chromosomes of 4th instar Anopheles darlingi Root were examined from multiple locations in the Brazilian Amazon. Minor modifications were made to existing polytene photomaps. These included changes to the breakpoint positions of several previously described paracentric inversions and descriptions of four new paracentric inversions, two on the right arm of chromosome 3 and two on the left arm of chromosome 3 that were found in multiple locations. A total of 18 inversions on the X (n = 1) chromosome, chromosome 2 (n = 7) and 3 (n = 11) were scored for 83 individuals from Manaus, Macapá and Porto Velho municipalities. The frequency of 2Ra inversion karyotypes in Manaus shows significant deficiency of heterozygotes (p < 0.0009). No significant linkage disequilibrium was found between inversions on chromosome 2 and 3. We hypothesize that at least two sympatric subpopulations exist within the An. darlingi population at Manaus based on inversion frequencies. PMID:27223867

Genetic Differentiation of Colombian Populations of Anopheles darlingi Root (Diptera: Culicidae).

PubMed

Rosero, C Y; Jaramillo, G I; Gonzalez, R; Cardenas, H

2017-10-01

Anopheles darlingi Root is a primary vector of malaria in the neotropic region, a species not just highly anthropophilic but very efficient in transmitting Plasmodium species and considered the most important vector in the Amazon region. The main goal of this study was to determine the genetic structure of the A. darlingi populations using microsatellites (STR) in western and eastern regions of Colombia. DNA extraction was done with the cited protocol of band using the Genomic Prep™ cell and tissue isolation commercial kits. We used the STR reported by Conn et al (Mol Ecol Notes 1: 223-225, 2001). The analysis with STR proved there was a high genetic diversity and significant alterations of the Hardy-Weinberg equilibrium. The greatest genetic diversity was recorded in Mitu (Vaupes) (Na = 14, Ho = 0.520). The lowest was in Pueblo Nuevo (Cordoba) (Na = 12, Ho = 0.457). The eastern region and the Mitu (Vaupes) populations presented the highest number of primer alleles (Ap = 30; Ap = 13; Ap = 9), with variations between 0.010 and 0.097. The AMOVA revealed that the whole population underwent moderate genetic differentiation (F ST  = 0.063, p < 0.05). The same differentiation was noticed (0.06 < F ST  > 0.06, p < 0.05) with five of the six populations included in this job, and there was a low differentiation in the Las Margaritas (Santander) area (F ST  = 0.02s3, p < 0.05). Our results suggest a slight positive correlation, which does not show a statistical significance between the geographic and genetic distances, probably suggesting that the moderate genetic differentiation found between pairs of populations does not need to be explained for the hypothesis of separation by distance.

Mixed-function oxidases and esterases associated with cross-resistance between DDT and lambda-cyhalothrin in Anopheles darlingi Root 1926 populations from Colombia.

PubMed

Fonseca-González, Idalyd; Quiñones, Martha L; McAllister, Janet; Brogdon, William G

2009-02-01

In order to establish the insecticide susceptibility status for Anopheles darlingi in Colombia, and as part of the National Network on Insecticide Resistance Surveillance, five populations of insects from three Colombian states were evaluated. Standardised WHO and CDC bottle bioassays, in addition to microplate biochemical assays, were conducted. Populations with mortality rates below 80% in the bioassays were considered resistant. All field populations were susceptible to deltamethrin, permethrin, malathion and fenitrothion. Resistance to lambda-cyhalothrin and DDT was detected in the Amé-Beté population using both bioassay methods with mortality rates of 65-75%. Enzyme levels related to insecticide resistance, including mixed function oxidases (MFO), non-specific esterases (NSE), glutathione S-transferases and modified acetylcholinesterase were evaluated in all populations and compared with a susceptible natural strain. Only mosquitoes from Amé-Beté presented significantly increased levels of both MFO and NSE, consistent with the low mortalities found in this population. The continued use of lambda-cyhalothrin for An. darlingi control in this locality has resulted in a natural resistance to this insecticide. In addition, DDT resistance is still present in this population, although this insecticide has not been used in Colombia since 1992. Increased metabolism through MFO and NSE may be involved in cross-resistance between lambda-cyhalothrin and DDT, although kdr-type nerve insensitivity cannot be discarded as a possible hypothesis. Additional research, including development of a kdr specific assay for An. darlingi should be conducted in future studies. Our data demonstrates the urgent need to develop local insecticide resistance management and surveillance programs throughout Colombia.

Larval control of Anopheles (Nyssorhinchus) darlingi using granular formulation of Bacillus sphaericus in abandoned gold-miners excavation pools in the Brazilian Amazon rainforest.

PubMed

Galardo, Allan Kardec Ribeiro; Zimmerman, Robert; Galardo, Clícia Denis

2013-01-01

Use of a Bacillus sphaericus based mosquito larvicide was evaluated as an intervention for malaria vector control at a mining site in Amapá, Brazil. Impacts on larval and adult densities of the primary vector Anopheles darlingi were measured over the course of a 52 week study period. In Calçoene, State of Amapá, gold mining activity occurs in 19 mining sites in gold-miners of Lourenço. Large pools are formed in mining sites and naturally colonized by Anopheles darlingi. During one year, the impact of applications of VectoLex® CG to these larval sources was evaluated. Applications of 20kg/ha were made as needed, based on 10 immature (3rd, 4th instars and pupae) surveillance of health and established thresholds. One hundred percent initial control was observed 48h after each treatment. The pools received from 2-10 (5.3±1.6) treatments during the year. The average re-treatment interval in productive pools was 9.4±4.3 weeks. During weeks 3-52 of the study, mean density of late stage larvae was 78% and pupae were 93% lower in the treated pools than in untreated pools (p< 0.0001, n=51) while reduction of adult mosquitoes was 53% in comparison to the untreated area during the last five months of the study, which were the rainy season (p<0.001). VectoLex® CG reduced immature Anopheles darlingi infestation levels during the entire study period, and reduced adult mosquito populations during the rainy season.

Malaria vectors in South America: current and future scenarios.

PubMed

Laporta, Gabriel Zorello; Linton, Yvonne-Marie; Wilkerson, Richard C; Bergo, Eduardo Sterlino; Nagaki, Sandra Sayuri; Sant'Ana, Denise Cristina; Sallum, Maria Anice Mureb

2015-08-19

Malaria remains a significant public health issue in South America. Future climate change may influence the distribution of the disease, which is dependent on the distribution of those Anopheles mosquitoes competent to transmit Plasmodium falciparum. Herein, predictive niche models of the habitat suitability for P. falciparum, the current primary vector Anopheles darlingi and nine other known and/or potential vector species of the Neotropical Albitarsis Complex, were used to document the current situation and project future scenarios under climate changes in South America in 2070. To build each ecological niche model, we employed topography, climate and biome, and the currently defined distribution of P. falciparum, An. darlingi and nine species comprising the Albitarsis Complex in South America. Current and future (i.e., 2070) distributions were forecast by projecting the fitted ecological niche model onto the current environmental situation and two scenarios of simulated climate change. Statistical analyses were performed between the parasite and each vector in both the present and future scenarios to address potential vector roles in the dynamics of malaria transmission. Current distributions of malaria vector species were associated with that of P. falciparum, confirming their role in transmission, especially An. darlingi, An. marajoara and An. deaneorum. Projected climate changes included higher temperatures, lower water availability and biome modifications. Regardless of future scenarios considered, the geographic distribution of P. falciparum was exacerbated in 2070 South America, with the distribution of the pathogen covering 35-46% of the continent. As the current primary vector An. darlingi showed low tolerance for drier environments, the projected climate change would significantly reduce suitable habitat, impacting both its distribution and abundance. Conversely, climate generalist members of the Albitarsis Complex showed significant spatial and

Serological response of cats to experimental Besnoitia darlingi and Besnoitia neotomofelis infections and prevalence of antibodies to these parasites in cats from Virginia and Pennsylvania

USDA-ARS?s Scientific Manuscript database

Besnoitia darlingi and B. neotomofelis are tissue cyst-forming apicomplexan parasite that use domestic cats (Felis domesticus) as definitive hosts and opossums (Didelphis virginiana) and southern planes woodrats (Neotoma micropus) as intermediate hosts, respectively. Nothing is known about the preva...

Microsatellite data suggest significant population structure and differentiation within the malaria vector Anopheles darlingi in Central and South America.

PubMed

Mirabello, Lisa; Vineis, Joseph H; Yanoviak, Stephen P; Scarpassa, Vera M; Póvoa, Marinete M; Padilla, Norma; Achee, Nicole L; Conn, Jan E

2008-03-26

Anopheles darlingi is the most important malaria vector in the Neotropics. An understanding of A. darlingi's population structure and contemporary gene flow patterns is necessary if vector populations are to be successfully controlled. We assessed population genetic structure and levels of differentiation based on 1,376 samples from 31 localities throughout the Peruvian and Brazilian Amazon and Central America using 5-8 microsatellite loci. We found high levels of polymorphism for all of the Amazonian populations (mean RS = 7.62, mean HO = 0.742), and low levels for the Belize and Guatemalan populations (mean RS = 4.3, mean HO = 0.457). The Bayesian clustering analysis revealed five population clusters: northeastern Amazonian Brazil, southeastern and central Amazonian Brazil, western and central Amazonian Brazil, Peruvian Amazon, and the Central American populations. Within Central America there was low non-significant differentiation, except for between the populations separated by the Maya Mountains. Within Amazonia there was a moderate level of significant differentiation attributed to isolation by distance. Within Peru there was no significant population structure and low differentiation, and some evidence of a population expansion. The pairwise estimates of genetic differentiation between Central America and Amazonian populations were all very high and highly significant (FST = 0.1859 - 0.3901, P < 0.05). Both the DA and FST distance-based trees illustrated the main division to be between Central America and Amazonia. We detected a large amount of population structure in Amazonia, with three population clusters within Brazil and one including the Peru populations. The considerable differences in Ne among the populations may have contributed to the observed genetic differentiation. All of the data suggest that the primary division within A. darlingi corresponds to two white gene genotypes between Amazonia (genotype 1) and Central America, parts of Colombia and

Effect of presynaptic membrane potential on electrical vs. chemical synaptic transmission

PubMed Central

Evans, Colin G.; Ludwar, Bjoern Ch.; Kang, Timothy

2011-01-01

The growing realization that electrical coupling is present in the mammalian brain has sparked renewed interest in determining its functional significance and contrasting it with chemical transmission. One question of interest is whether the two types of transmission can be selectively regulated, e.g., if a cell makes both types of connections can electrical transmission occur in the absence of chemical transmission? We explore this issue in an experimentally advantageous preparation. B21, the neuron we study, is an Aplysia sensory neuron involved in feeding that makes electrical and chemical connections with other identified cells. Previously we demonstrated that chemical synaptic transmission is membrane potential dependent. It occurs when B21 is centrally depolarized prior to and during peripheral activation, but does not occur if B21 is peripherally activated at its resting membrane potential. In this article we study effects of membrane potential on electrical transmission. We demonstrate that maximal potentiation occurs in different voltage ranges for the two types of transmission, with potentiation of electrical transmission occurring at more hyperpolarized potentials (i.e., requiring less central depolarization). Furthermore, we describe a physiologically relevant type of stimulus that induces both spiking and an envelope of depolarization in the somatic region of B21. This depolarization does not induce functional chemical synaptic transmission but is comparable to the depolarization needed to maximally potentiate electrical transmission. In this study we therefore characterize a situation in which electrical and chemical transmission can be selectively controlled by membrane potential. PMID:21593394

Host nutrition alters the variance in parasite transmission potential

PubMed Central

Vale, Pedro F.; Choisy, Marc; Little, Tom J.

2013-01-01

The environmental conditions experienced by hosts are known to affect their mean parasite transmission potential. How different conditions may affect the variance of transmission potential has received less attention, but is an important question for disease management, especially if specific ecological contexts are more likely to foster a few extremely infectious hosts. Using the obligate-killing bacterium Pasteuria ramosa and its crustacean host Daphnia magna, we analysed how host nutrition affected the variance of individual parasite loads, and, therefore, transmission potential. Under low food, individual parasite loads showed similar mean and variance, following a Poisson distribution. By contrast, among well-nourished hosts, parasite loads were right-skewed and overdispersed, following a negative binomial distribution. Abundant food may, therefore, yield individuals causing potentially more transmission than the population average. Measuring both the mean and variance of individual parasite loads in controlled experimental infections may offer a useful way of revealing risk factors for potential highly infectious hosts. PMID:23407498

Host nutrition alters the variance in parasite transmission potential.

PubMed

Vale, Pedro F; Choisy, Marc; Little, Tom J

2013-04-23

The environmental conditions experienced by hosts are known to affect their mean parasite transmission potential. How different conditions may affect the variance of transmission potential has received less attention, but is an important question for disease management, especially if specific ecological contexts are more likely to foster a few extremely infectious hosts. Using the obligate-killing bacterium Pasteuria ramosa and its crustacean host Daphnia magna, we analysed how host nutrition affected the variance of individual parasite loads, and, therefore, transmission potential. Under low food, individual parasite loads showed similar mean and variance, following a Poisson distribution. By contrast, among well-nourished hosts, parasite loads were right-skewed and overdispersed, following a negative binomial distribution. Abundant food may, therefore, yield individuals causing potentially more transmission than the population average. Measuring both the mean and variance of individual parasite loads in controlled experimental infections may offer a useful way of revealing risk factors for potential highly infectious hosts.

Potential effect of climate change on malaria transmission in Africa.

PubMed

Tanser, Frank C; Sharp, Brian; le Sueur, David

2003-11-29

Climate change is likely to affect transmission of vector-borne diseases such as malaria. We quantitatively estimated current malaria exposure and assessed the potential effect of projected climate scenarios on malaria transmission. We produced a spatiotemporally validated (against 3791 parasite surveys) model of Plasmodium falciparum malaria transmission in Africa. Using different climate scenarios from the Hadley Centre global climate model (HAD CM3) climate experiments, we projected the potential effect of climate change on transmission patterns. Our model showed sensitivity and specificity of 63% and 96%, respectively (within 1 month temporal accuracy), when compared with the parasite surveys. We estimate that on average there are 3.1 billion person-months of exposure (445 million people exposed) in Africa per year. The projected scenarios would estimate a 5-7% potential increase (mainly altitudinal) in malaria distribution with surprisingly little increase in the latitudinal extents of the disease by 2100. Of the overall potential increase (although transmission will decrease in some countries) of 16-28% in person-months of exposure (assuming a constant population), a large proportion will be seen in areas of existing transmission. The effect of projected climate change indicates that a prolonged transmission season is as important as geographical expansion in correct assessment of the effect of changes in transmission patterns. Our model constitutes a valid baseline against which climate scenarios can be assessed and interventions planned.

Risk of daytime transmission of malaria in the French Guiana rain forest.

PubMed

Pommier de Santi, V; Dusfour, I; de Parseval, E; Lespinet, B; Nguyen, C; Gaborit, P; Carinci, R; Hyvert, G; Girod, R; Briolant, S

2017-02-01

Between 2008 and 2014, there were 1070 malaria cases reported in French Guiana among members of the armed forces. Most of the malaria outbreaks investigated were multifactorial and followed missions conducted at illegal gold mining sites. For example, a malaria outbreak occurred in September 2013, three weeks after the deployment of 15 soldiers at Dagobert, which is such a site. The attack rate was 53%, with seven Plasmodium vivax infections and one coinfection with both Plasmodium vivax and Plasmodium falciparum. Two months later, an entomological investigation in the field caught 321 anopheles by the human landing catch method. Among them, 282 were Anopheles darlingi. One specimen was PCR-positive for P. vivax, for an infection rate of 0.4% (1/282). In 15.7% of these cases, the An. darlingi was caught during the day. The existence of daytime biting activity by An. darlingi in the Guianese forest might play a key role in malaria outbreaks among military personnel. This finding requires that the Army Health Service adapt its recommendations concerning malaria prevention in French Guiana.

Interesting features of transmission across locally periodic delta potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dharani, M., E-mail: m-dharani@blr.amrita.edu, E-mail: mdharu@yahoo.co.in; Shastry, C. S.

2016-05-23

We study the theory of transmission of electrons through N delta potential barriers as well as wells. Some of the interesting features like the correlation between resonance peak positions and box states, number of peaks in transmission band and bound states are analyzed for locally periodic attractive, repulsive and pair of attractive and repulsive potentials.

Quantifying the transmission potential of pandemic influenza

NASA Astrophysics Data System (ADS)

Chowell, Gerardo; Nishiura, Hiroshi

2008-03-01

This article reviews quantitative methods to estimate the basic reproduction number of pandemic influenza, a key threshold quantity to help determine the intensity of interventions required to control the disease. Although it is difficult to assess the transmission potential of a probable future pandemic, historical epidemiologic data is readily available from previous pandemics, and as a reference quantity for future pandemic planning, mathematical and statistical analyses of historical data are crucial. In particular, because many historical records tend to document only the temporal distribution of cases or deaths (i.e. epidemic curve), our review focuses on methods to maximize the utility of time-evolution data and to clarify the detailed mechanisms of the spread of influenza. First, we highlight structured epidemic models and their parameter estimation method which can quantify the detailed disease dynamics including those we cannot observe directly. Duration-structured epidemic systems are subsequently presented, offering firm understanding of the definition of the basic and effective reproduction numbers. When the initial growth phase of an epidemic is investigated, the distribution of the generation time is key statistical information to appropriately estimate the transmission potential using the intrinsic growth rate. Applications of stochastic processes are also highlighted to estimate the transmission potential using similar data. Critically important characteristics of influenza data are subsequently summarized, followed by our conclusions to suggest potential future methodological improvements.

Spatial clustering and longitudinal variation of Anopheles darlingi (Diptera: Culicidae) larvae in a river of the Amazon: the importance of the forest fringe and of obstructions to flow in frontier malaria.

PubMed

Barros, F S M; Arruda, M E; Gurgel, H C; Honório, N A

2011-12-01

Deforestation has been linked to a rise in malaria prevalence. In this paper, we studied longitudinally 20 spots, including forested and deforested portions of a temporary river in a malarigenous frontier zone. Larval habitat parameters influencing distribution of Anopheles darlingi (Diptera: Culicidae) larvae were studied. We observed that larvae were clustered in forested-deforested transitions. For the first time in the literature, it was verified that parameters determining larval distribution varied from deforested to forested areas. The proximity to human dwellings was also a significant factor determining distribution, but larvae was most importantly associated with a previously undescribed parameter, the presence of small obstructions to river flow, such as tree trunks within the river channel, which caused pooling of water during the dry season ('microdams'). In deforested areas, the most important factor determining distribution of larvae was shade (reduced luminance). Larvae were absent in the entire studied area during the wet season and present in most sites during the dry season. During the wet-dry transition, larvae were found sooner in areas with microdams, than in other areas, suggesting that flow obstruction prolongs the breeding season of An. darlingi. Adult mosquito densities and malaria incidence were higher during the dry season. Our data correlate well with the published literature, including the distribution of malaria cases near the forest fringes, and has permitted the creation of a model of An. darlingi breeding, where preference for sites with reduced luminance, human presence and microdams would interact to determine larval distribution.

Abundance, behavior and entomological inoculation rates of anthropophilic anophelines from a primary Colombian malaria endemic area

PubMed Central

2013-01-01

Background In Colombia for several years, the Urabá-Bajo Cauca and Alto Sinú region has registered the highest numbers of malaria cases in the country. Malaria vector incrimination and the characterization of entomological parameters will allow for a better understanding of malaria transmission dynamics and the design of effective vector control strategies for this region. Methods We conducted a longitudinal survey between November 2008 and June 2010 to quantify entomological (abundance and biting activity) and transmission parameters, including infection rate (IR) and entomological inoculation rate (EIR), to incriminate potential anopheline vectors in three localities of a major Colombian malaria endemic region, the Urabá-Bajo Cauca and Alto Sinú: La Capilla, Juan Jose and El Loro. Results A total of 5,316 anopheline mosquitoes corresponding to seven species were collected. Anopheles nuneztovari (69.5%) and Anopheles darlingi (22.2%) were the most abundant species, followed by Anopheles pseudopunctipennis (4.5%), Anopheles albitarsis s.l. (2%), Anopheles triannulatus lineage Northwest (1.8%), Anopheles punctimacula and Anopheles argyritarsis (at < 1%, each). Three species were naturally infected with Plasmodium vivax, An. nuneztovari, An. darlingi (IRs < 1%) and An. triannulatus (IR = 1.5%). Annual EIRs for these species ranged from 3.5 to 4.8 infective bites per year. Conclusions These results indicate that An. nuneztovari and An. darlingi continue to be the most important malaria vectors in this region. Anopheles triannulatus, a species of local importance in other South American countries was found naturally infected with Plasmodium vivax VK247; therefore, further work should be directed to understand if this species has a role in malaria transmission in this region. PMID:23497535

Abundance, behavior and entomological inoculation rates of anthropophilic anophelines from a primary Colombian malaria endemic area.

PubMed

Naranjo-Diaz, Nelson; Rosero, Doris A; Rua-Uribe, Guillermo; Luckhart, Shirley; Correa, Margarita M

2013-03-07

In Colombia for several years, the Urabá-Bajo Cauca and Alto Sinú region has registered the highest numbers of malaria cases in the country. Malaria vector incrimination and the characterization of entomological parameters will allow for a better understanding of malaria transmission dynamics and the design of effective vector control strategies for this region. We conducted a longitudinal survey between November 2008 and June 2010 to quantify entomological (abundance and biting activity) and transmission parameters, including infection rate (IR) and entomological inoculation rate (EIR), to incriminate potential anopheline vectors in three localities of a major Colombian malaria endemic region, the Urabá-Bajo Cauca and Alto Sinú: La Capilla, Juan Jose and El Loro. A total of 5,316 anopheline mosquitoes corresponding to seven species were collected. Anopheles nuneztovari (69.5%) and Anopheles darlingi (22.2%) were the most abundant species, followed by Anopheles pseudopunctipennis (4.5%), Anopheles albitarsis s.l. (2%), Anopheles triannulatus lineage Northwest (1.8%), Anopheles punctimacula and Anopheles argyritarsis (at  < 1%, each). Three species were naturally infected with Plasmodium vivax, An. nuneztovari, An. darlingi (IRs  < 1%) and An. triannulatus (IR = 1.5%). Annual EIRs for these species ranged from 3.5 to 4.8 infective bites per year. These results indicate that An. nuneztovari and An. darlingi continue to be the most important malaria vectors in this region. Anopheles triannulatus, a species of local importance in other South American countries was found naturally infected with Plasmodium vivax VK247; therefore, further work should be directed to understand if this species has a role in malaria transmission in this region.

A Population Genetics Study of Anopheles Darlingi (Diptera: Culicidae) from Colombia Based on Random Amplified Polymorphic DNA-Polymerase Chain Reaction and Amplified Fragment Length Polymorphism Markers

DTIC Science & Technology

2007-06-01

Biology of Disease Vectors, University Press of Colorado. Niwot, co. p. 417-437. Tadei WI’, Santos JMN, Rabbani MG 1982. Biologia de anofelinos amazonicos...wR 4𔃼.0 Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 102(3): 255-262, June 2007 255 A population genetics study ofAnopheles darlingi (Diptera... de Ciencias y rdcullad de Salud. Universidad del Valle, (’.ali, Colombia *Depanment of Entomology, Walter Reed Army Institute of Research. Silver

Malaria transmission potential could be reduced with current and future climate change.

PubMed

Murdock, C C; Sternberg, E D; Thomas, M B

2016-06-21

Several studies suggest the potential for climate change to increase malaria incidence in cooler, marginal transmission environments. However, the effect of increasing temperature in warmer regions where conditions currently support endemic transmission has received less attention. We investigate how increases in temperature from optimal conditions (27 °C to 30 °C and 33 °C) interact with realistic diurnal temperature ranges (DTR: ± 0 °C, 3 °C, and 4.5 °C) to affect the ability of key vector species from Africa and Asia (Anopheles gambiae and An. stephensi) to transmit the human malaria parasite, Plasmodium falciparum. The effects of increasing temperature and DTR on parasite prevalence, parasite intensity, and mosquito mortality decreased overall vectorial capacity for both mosquito species. Increases of 3 °C from 27 °C reduced vectorial capacity by 51-89% depending on species and DTR, with increases in DTR alone potentially halving transmission. At 33 °C, transmission potential was further reduced for An. stephensi and blocked completely in An. gambiae. These results suggest that small shifts in temperature could play a substantial role in malaria transmission dynamics, yet few empirical or modeling studies consider such effects. They further suggest that rather than increase risk, current and future warming could reduce transmission potential in existing high transmission settings.

Prevalence of antibodies to Trypanosoma cruzi, Toxoplasma gondii, Encephalitozoon cuniculi, Sarcocystis neurona, Besnoitia darlingi, and Neospora caninum in North American opossums, Didelphis virginiana, from southern Louisiana.

PubMed

Houk, Alice E; Goodwin, David G; Zajac, Anne M; Barr, Stephen C; Dubey, J P; Lindsay, David S

2010-12-01

We examined the prevalence of antibodies to zoonotic protozoan parasites ( Trypanosoma cruzi, Toxoplasma gondii, and Encephalitozoon cuniculi) and protozoans of veterinary importance ( Neospora caninum, Sarcocystis neurona, and Besnoitia darlingi) in a population of North American opossums ( Didelphis virginiana) from Louisiana. Samples from 30 opossums were collected as part of a survey for T. cruzi in Louisiana. Frozen sera from these 30 opossums were examined using an indirect immunofluorescent antibody test (IFAT) against in vitro-produced antigenic stages of these protozoans. Additionally, 24 of the 30 samples were examined using hemoculture, and all 30 were examined in the modified direct agglutination test (MAT) for antibodies to To. gondii. The prevalences of reactive IFAT samples were as follows: 60% for T. cruzi, 27% for To. gondii, 23% for E. cuniculi, 17% for S. neurona, 47% for B. darlingi, and 0% for N. caninum. Hemoculture revealed that 16 (67%) of 24 samples were positive for T. cruzi, compared to 18 of 30 (60%) by IFAT. The sensitivity and specificity for the IFAT compared to hemoculture was 100% for each. The modified direct agglutination test revealed that 9 (30%) of the 30 samples from opossums had antibodies to To. gondii , compared to 8 (27%) using the IFAT. The sensitivity and specificity of the IFAT compared to the MAT was 100% and 72%, respectively.

The potential of electricity transmission corridors in forested areas as bumblebee habitat.

PubMed

Hill, Bruce; Bartomeus, Ignasi

2016-11-01

Declines in pollinator abundance and diversity are not only a conservation issue, but also a threat to crop pollination. Maintained infrastructure corridors, such as those containing electricity transmission lines, are potentially important wild pollinator habitat. However, there is a lack of evidence comparing the abundance and diversity of wild pollinators in transmission corridors with other important pollinator habitats. We compared the diversity of a key pollinator group, bumblebees ( Bombus spp.), between transmission corridors and the surrounding semi-natural and managed habitat types at 10 sites across Sweden's Uppland region. Our results show that transmission corridors have no impact on bumblebee diversity in the surrounding area. However, transmission corridors and other maintained habitats such as roadsides have a level of bumblebee abundance and diversity comparable to semi-natural grasslands and host species that are important for conservation and ecosystem service provision. Under the current management regime, transmission corridors already provide valuable bumblebee habitat, but given that host plant density is the main determinant of bumblebee abundance, these areas could potentially be enhanced by establishing and maintaining key host plants. We show that in northern temperate regions the maintenance of transmission corridors has the potential to contribute to bumblebee conservation and the ecosystem services they provide.

The potential of electricity transmission corridors in forested areas as bumblebee habitat

PubMed Central

Hill, Bruce

2016-01-01

Declines in pollinator abundance and diversity are not only a conservation issue, but also a threat to crop pollination. Maintained infrastructure corridors, such as those containing electricity transmission lines, are potentially important wild pollinator habitat. However, there is a lack of evidence comparing the abundance and diversity of wild pollinators in transmission corridors with other important pollinator habitats. We compared the diversity of a key pollinator group, bumblebees (Bombus spp.), between transmission corridors and the surrounding semi-natural and managed habitat types at 10 sites across Sweden's Uppland region. Our results show that transmission corridors have no impact on bumblebee diversity in the surrounding area. However, transmission corridors and other maintained habitats such as roadsides have a level of bumblebee abundance and diversity comparable to semi-natural grasslands and host species that are important for conservation and ecosystem service provision. Under the current management regime, transmission corridors already provide valuable bumblebee habitat, but given that host plant density is the main determinant of bumblebee abundance, these areas could potentially be enhanced by establishing and maintaining key host plants. We show that in northern temperate regions the maintenance of transmission corridors has the potential to contribute to bumblebee conservation and the ecosystem services they provide. PMID:28018640

Predicting potential ranges of primary malaria vectors and malaria in northern South America based on projected changes in climate, land cover and human population.

PubMed

Alimi, Temitope O; Fuller, Douglas O; Qualls, Whitney A; Herrera, Socrates V; Arevalo-Herrera, Myriam; Quinones, Martha L; Lacerda, Marcus V G; Beier, John C

2015-08-20

Changes in land use and land cover (LULC) as well as climate are likely to affect the geographic distribution of malaria vectors and parasites in the coming decades. At present, malaria transmission is concentrated mainly in the Amazon basin where extensive agriculture, mining, and logging activities have resulted in changes to local and regional hydrology, massive loss of forest cover, and increased contact between malaria vectors and hosts. Employing presence-only records, bioclimatic, topographic, hydrologic, LULC and human population data, we modeled the distribution of malaria and two of its dominant vectors, Anopheles darlingi, and Anopheles nuneztovari s.l. in northern South America using the species distribution modeling platform Maxent. Results from our land change modeling indicate that about 70,000 km(2) of forest land would be lost by 2050 and 78,000 km(2) by 2070 compared to 2010. The Maxent model predicted zones of relatively high habitat suitability for malaria and the vectors mainly within the Amazon and along coastlines. While areas with malaria are expected to decrease in line with current downward trends, both vectors are predicted to experience range expansions in the future. Elevation, annual precipitation and temperature were influential in all models both current and future. Human population mostly affected An. darlingi distribution while LULC changes influenced An. nuneztovari s.l. distribution. As the region tackles the challenge of malaria elimination, investigations such as this could be useful for planning and management purposes and aid in predicting and addressing potential impediments to elimination.

Potential impacts of nanotechnology on energy transmission applications and needs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elcock, D.; Environmental Science Division

2007-11-30

The application of nanotechnologies to energy transmission has the potential to significantly impact both the deployed transmission technologies and the need for additional development. This could be a factor in assessing environmental impacts of right-of-way (ROW) development and use. For example, some nanotechnology applications may produce materials (e.g., cables) that are much stronger per unit volume than existing materials, enabling reduced footprints for construction and maintenance of electricity transmission lines. Other applications, such as more efficient lighting, lighter-weight materials for vehicle construction, and smaller batteries having greater storage capacities may reduce the need for long-distance transport of energy, and possiblymore » reduce the need for extensive future ROW development and many attendant environmental impacts. This report introduces the field of nanotechnology, describes some of the ways in which processes and products developed with or incorporating nanomaterials differ from traditional processes and products, and identifies some examples of how nanotechnology may be used to reduce potential ROW impacts. Potential environmental, safety, and health impacts are also discussed.« less

Nightly biting cycles of malaria vectors in a heterogeneous transmission area of eastern Amazonian Brazil

PubMed Central

2013-01-01

Background The biting cycle of anopheline mosquitoes is an important component in the transmission of malaria. Inter- and intraspecific biting patterns of anophelines have been investigated using the number of mosquitoes caught over time to compare general tendencies in host-seeking activity and cumulative catch. In this study, all-night biting catch data from 32 consecutive months of collections in three riverine villages were used to compare biting cycles of the five most abundant vector species using common statistics to quantify variability and deviations of nightly catches from a normal distribution. Methods Three communities were selected for study. All-night human landing catches of mosquitoes were made each month in the peridomestic environment of four houses (sites) for nine consecutive days from April 2003 to November 2005. Host-seeking activities of the five most abundant species that were previously captured infected with Plasmodium falciparum, Plasmodium malariae or Plasmodium vivax, were analysed and compared by measuring the amount of variation in numbers biting per unit time (co-efficient of variation, V), the degree to which the numbers of individuals per unit time were asymmetrical (skewness = g1) and the relative peakedness or flatness of the distribution (kurtosis = g2). To analyse variation in V, g1, and g2 within species and villages, we used mixed model nested ANOVAs (PROC GLM in SAS) with independent variables (sources of variation): year, month (year), night (year X month) and collection site (year X month). Results The biting cycles of the most abundant species, Anopheles darlingi, had the least pronounced biting peaks, the lowest mean V values, and typically non-significant departures from normality in g1 and g2. By contrast, the species with the most sharply defined crepuscular biting peaks, Anopheles marajoara, Anopheles nuneztovari and Anopheles triannulatus, showed high to moderate mean V values and, most commonly, significantly

Alternative feeding strategies and potential disease transmission in Wisconsin white-tailed deer

USGS Publications Warehouse

Thompson, A.K.; Samuel, M.D.; VanDeelen, T.R.

2008-01-01

We conducted experimental feeding using 3 feeding methods (pile, spread, trough) and 2 quantities (rationed, ad libitum) of shelled corn to compare deer activity and behavior with control sites and evaluate potential direct and indirect transmission of infectious disease in white-tailed deer (Odocoileus virginianus) in central Wisconsin, USA. Deer use was higher at 2 of the feeding sites than at natural feeding areas (P ??? 0.02). Deer spent a higher proportion of time (P < 0.01) feeding at pile (49%) and spread (61%) treatments than at natural feeding areas (36%). We found higher deer use for rationed than ad libitum feeding quantities and feeding intensity was greatest at rationed piles and lowest at ad libitum spreads. We also observed closer pairwise distances (???0.3 m) among deer when corn was provided in a trough relative to spread (P=0.03). Supplemental feeding poses risks for both direct and indirect disease transmission due to higher deer concentration and more intensive use relative to control areas. Concentrated feeding and contact among deer at feeding sites can also increase risk for disease transmission. Our results indicated that restrictions on feeding quantity would not mitigate the potential for disease transmission None of the feeding strategies we evaluated substantially reduced the potential risk for disease transmission and banning supplemental feeding to reduce transmission is warranted.

Impact of insurance coverage on HIV transmission potential among antiretroviral therapy-treated youth living with HIV.

PubMed

Wood, Sarah; Ratcliffe, Sarah; Gowda, Charitha; Lee, Susan; Dowshen, Nadia L; Gross, Robert

2018-04-24

To identify the prevalence of high HIV transmission potential in a cohort of youth living with HIV (YLWH), and determine the impact of insurance coverage on potential for HIV transmission. Retrospective cohort study of antiretroviral therapy (ART)-treated YLWH at a US adolescent HIV clinic, 2002-2015. The primary exposure was presence or absence of insurance, defined as private, public or pharmacy-only coverage. The primary outcome was high HIV transmission potential, defined as time-concurrent incident bacterial sexually transmitted infections (STI) (gonorrhea, chlamydia or syphilis) and HIV RNA greater than 1500 copies/ml. Marginal structural models adjusting for baseline demographic covariates, prior history of STI and time-varying retention in care assessed the relationship between insurance status and HIV transmission potential. Participants (n = 240) were followed for a median of 22 (IQR 8.1-49) months after ART initiation, and were predominately African-American men and transgender women who have sex with men, with a median age at HIV diagnosis of 19 years (IQR 17-21). We identified 37 (15%) participants with at least one episode of high HIV transmission potential. Insurance coverage was associated with a greater than 50% lower odds of high HIV transmission potential (aOR 0.46, 95% CI 0.26-0.84), and history of STI at or before entry to HIV care conferred more than three-fold higher odds of high transmission potential (aOR 3.21, 95% CI 1.55-6.63). We found 15% of YLWH to have episodic high HIV transmission potential despite receiving ART. Insurance coverage, including pharmacy-only benefits, was protective against transmission risk, suggesting a pivotal role for universal ART coverage in treatment as prevention.

Brazilian mosquito (Diptera: Culicidae) fauna: I. Anopheles species from Porto Velho, Rondônia state, western Amazon, Brazil.

PubMed

Morais, Sirlei Antunes; Urbinatti, Paulo Roberto; Sallum, Maria Anice Mureb; Kuniy, Adriana Akemi; Moresco, Gilberto Gilmar; Fernandes, Aristides; Nagaki, Sandra Sayuri; Natal, Delsio

2012-12-01

This study contributes to knowledge of Anopheles species, including vectors of Plasmodium from the western Brazilian Amazon in Porto Velho, Rondônia State. The sampling area has undergone substantial environmental changes as a consequence of agricultural and hydroelectric projects, which have caused intensive deforestation and favored habitats for some mosquito species. The purpose of this study was to diagnose the occurrence of anopheline species from collections in three locations along an electric-power transmission line. Each locality was sampled three times from 2010 to 2011. The principal adult mosquitoes captured in Shannon trap were Anopheles darlingi, An. triannulatus, An. nuneztovari l.s., An.gilesi and An. costai. In addition, larvae were collected in ground breeding sites for Anopheles braziliensis, An. triannulatus, An. darlingi, An. deaneorum, An. marajoara, An. peryassui, An. nuneztovari l.s. and An. oswaldoi-konderi. Anopheles darlingi was the most common mosquito in the region. We discuss Culicidae systematics, fauna distribution, and aspects of malaria in altered habitats of the western Amazon.

Circadian rhythms of locomotor activity in the subterranean Mashona mole rat, Cryptomys darlingi.

PubMed

Vasicek, Caroline A; Oosthuizen, Maria K; Cooper, Howard M; Bennett, Nigel C

2005-02-15

The Mashona mole rat, Cryptomys darlingi, is a social, subterranean African rodent that is rarely, if ever, exposed to light, and that exhibits a regressed visual system. This study investigated locomotor activity patterns of Mashona mole rats (n=12) under different light cycles. Activity was measured using either infrared captors (n=8) or running wheels (n=4). The mole rats entrained their activity to a standard (LD 12:12) photoperiod. They displayed either a nocturnal or diurnal activity preference with one bout of activity and one bout of rest. Therefore, as a species, the Mashona mole rat did not show a clear nocturnal or diurnal activity preference. When the LD (12:12) light cycle was inversed, the animals switched their activity, too. Under constant dark (DD), most mole rats (73%) showed a free-running circadian activity rhythm, but under constant light (LL), only some (36%) did. The free-run period of the rhythm (tau) ranged from 23.83 to 24.10 h. The remaining animals were arrhythmic. There was large interindividual and intraindividual variations in the rate and extent of entrainment, time of activity preference, and activity patterns. Possible reasons for the observed variations are discussed. It is concluded that the Mashona mole rat has an endogenous activity rhythm which approximates 24 h, that the mole rat can distinguish between light and dark, and that the endogenous clock utilises this photic information as a zeitgeber.

Melatonin secretion in the Mashona mole-rat, Cryptomys darlingi--influence of light on rhythmicity.

PubMed

Vasicek, Caroline A; Malpaux, Benoît; Fleming, Patricia A; Bennett, Nigel C

2005-01-17

The hormone melatonin is synthesised and secreted from the pineal gland in darkness and triggers the daily and seasonal timing of various physiological and behavioural processes. The Mashona mole-rat, Cryptomys darlingi, lives in subterranean burrows that are completely sealed and is therefore rarely, if ever, exposed to light under natural conditions. Hence, this species is of particular interest for studies on rhythms of melatonin secretion. We investigated how plasma melatonin concentrations of the Mashona mole-rat responded to exposure to a long-term standard photoperiod of 12 h light, 12 h dark (12:12 LD), constant light (LL) and constant dark (DD). In addition, we examined whether plasma melatonin concentration was coupled to locomotor activity. Mashona mole-rats displayed rhythms of plasma melatonin concentration that appeared entrained to the standard LD photoperiod, suggesting that the mole-rat is capable of perceiving and entraining to this photic zeitgeber. Furthermore, under chronic constant lighting conditions (DD, LL), circadian rhythms in plasma melatonin concentration were observed, suggesting the possible existence of an endogenous rhythm. Light suppressed melatonin secretion, but constant light did not abolish the rhythm of plasma melatonin concentration. Between active and non-active animals, no difference in plasma melatonin concentration was found for any of the sequential photoperiods (LD1 DD, LD2, LL), tentatively suggesting that the rhythm of melatonin secretion is uncoupled from that of locomotor activity.

The ecological foundations of transmission potential and vector-borne disease in urban landscapes.

PubMed

LaDeau, Shannon L; Allan, Brian F; Leisnham, Paul T; Levy, Michael Z

2015-07-01

Urban transmission of arthropod-vectored disease has increased in recent decades. Understanding and managing transmission potential in urban landscapes requires integration of sociological and ecological processes that regulate vector population dynamics, feeding behavior, and vector-pathogen interactions in these unique ecosystems. Vectorial capacity is a key metric for generating predictive understanding about transmission potential in systems with obligate vector transmission. This review evaluates how urban conditions, specifically habitat suitability and local temperature regimes, and the heterogeneity of urban landscapes can influence the biologically-relevant parameters that define vectorial capacity: vector density, survivorship, biting rate, extrinsic incubation period, and vector competence.Urban landscapes represent unique mosaics of habitat. Incidence of vector-borne disease in urban host populations is rarely, if ever, evenly distributed across an urban area. The persistence and quality of vector habitat can vary significantly across socio-economic boundaries to influence vector species composition and abundance, often generating socio-economically distinct gradients of transmission potential across neighborhoods.Urban regions often experience unique temperature regimes, broadly termed urban heat islands (UHI). Arthropod vectors are ectothermic organisms and their growth, survival, and behavior are highly sensitive to environmental temperatures. Vector response to UHI conditions is dependent on regional temperature profiles relative to the vector's thermal performance range. In temperate climates UHI can facilitate increased vector development rates while having countervailing influence on survival and feeding behavior. Understanding how urban heat island (UHI) conditions alter thermal and moisture constraints across the vector life cycle to influence transmission processes is an important direction for both empirical and modeling research.There remain

Transmission potential of influenza A/H7N9, February to May 2013, China

PubMed Central

2013-01-01

Background On 31 March 2013, the first human infections with the novel influenza A/H7N9 virus were reported in Eastern China. The outbreak expanded rapidly in geographic scope and size, with a total of 132 laboratory-confirmed cases reported by 3 June 2013, in 10 Chinese provinces and Taiwan. The incidence of A/H7N9 cases has stalled in recent weeks, presumably as a consequence of live bird market closures in the most heavily affected areas. Here we compare the transmission potential of influenza A/H7N9 with that of other emerging pathogens and evaluate the impact of intervention measures in an effort to guide pandemic preparedness. Methods We used a Bayesian approach combined with a SEIR (Susceptible-Exposed-Infectious-Removed) transmission model fitted to daily case data to assess the reproduction number (R) of A/H7N9 by province and to evaluate the impact of live bird market closures in April and May 2013. Simulation studies helped quantify the performance of our approach in the context of an emerging pathogen, where human-to-human transmission is limited and most cases arise from spillover events. We also used alternative approaches to estimate R based on individual-level information on prior exposure and compared the transmission potential of influenza A/H7N9 with that of other recent zoonoses. Results Estimates of R for the A/H7N9 outbreak were below the epidemic threshold required for sustained human-to-human transmission and remained near 0.1 throughout the study period, with broad 95% credible intervals by the Bayesian method (0.01 to 0.49). The Bayesian estimation approach was dominated by the prior distribution, however, due to relatively little information contained in the case data. We observe a statistically significant deceleration in growth rate after 6 April 2013, which is consistent with a reduction in A/H7N9 transmission associated with the preemptive closure of live bird markets. Although confidence intervals are broad, the estimated

Epidemiological and entomological studies of a malaria outbreak among French armed forces deployed at illegal gold mining sites reveal new aspects of the disease's transmission in French Guiana.

PubMed

Pommier de Santi, Vincent; Girod, Romain; Mura, Marie; Dia, Aissata; Briolant, Sébastien; Djossou, Félix; Dusfour, Isabelle; Mendibil, Alexandre; Simon, Fabrice; Deparis, Xavier; Pagès, Frédéric

2016-01-22

In December 2010, a Plasmodium vivax malaria outbreak occurred among French forces involved in a mission to control illegal gold mining in French Guiana. The findings of epidemiological and entomological investigations conducted after this outbreak are presented here. Data related to malaria cases reported to the French armed forces epidemiological surveillance system were collected during the epidemic period from December 2010 to April 2011. A retrospective cohort study was conducted to identify presumed contamination sites. Anopheles mosquitoes were sampled at the identified sites using Mosquito Magnet and CDC light traps. Specimens were identified morphologically and confirmed using molecular methods (sequencing of ITS2 gene and/or barcoding). Anopheles infections with Plasmodium falciparum and P. vivax were tested by both enzyme-linked immunosorbent assay and real-time PCR. Seventy-two P. vivax malaria cases were reported (three were mixed P. falciparum/P. vivax infections), leading to a global attack rate of 26.5% (72/272). Lack of compliance with vector control measures and doxycycline chemoprophylaxis was reported by patients. Two illegal gold mining sites located in remote areas in the primary forest were identified as places of contamination. In all, 595 Anopheles females were caught and 528 specimens were formally identified: 305 Anopheles darlingi, 145 Anopheles nuneztovari s.l., 63 Anopheles marajoara and 15 Anopheles triannulatus s.l. Three An. darlingi were infected by P. falciparum (infection rate: 1.1%) and four An. marajoara by P. vivax (infection rate: 6.4%). The main drivers of the outbreak were the lack of adherence by military personnel to malaria prevention measures and the high level of malaria transmission at illegal gold mining sites. Anopheles marajoara was clearly implicated in malaria transmission for the first time in French Guiana. The high infection rates observed confirm that illegal gold mining sites must be considered as high level

MALARIA VECTORS IN SAN JOSÉDEL GUAVIARE, ORINOQUIA, COLOMBIA

PubMed Central

JIMÉNEZ, IRENE P.; CONN, JAN E.; BROCHERO, HELENA

2015-01-01

This study was conducted to determine Anopheles species composition and their natural infectivity by human Plasmodium in 2 localities with the highest malaria transmission in San Jose del Guaviare, Guaviare, Colombia. A total of 1,009 Anopheles mosquitoes were collected using human landing catches during 8 months in 2010. Anopheles darlingi was the most abundant (83.2%) followed by An. albitarsis s.l. (8.6%), Anopheles braziliensis (3.8%), An. oswaldoi s.l. (1%), and An. rangeli (0.3%). Anopheles darlingi showed the highest human biting rate, and it was found naturally infected with Plasmodium vivax VK210 (0.119%) using enzyme-linked immunosorbent assays. All species were collected biting both indoors and outdoors. Anopheles darlingi showed biting activity overnight with an indoor peak between 1200–0100 h. Therefore, we recommend that malaria prevention strategies focus on 1) insecticide-treated nets to reduce human–vector contact when people are most exposed and unprotected; 2) accurate diagnoses; 3) adequate treatment for patients; 4) more timely epidemiological notification; and 5) improved entomological surveillance. PMID:25102591

Chikungunya virus transmission potential by local Aedes mosquitoes in the Americas and Europe.

PubMed

Vega-Rúa, Anubis; Lourenço-de-Oliveira, Ricardo; Mousson, Laurence; Vazeille, Marie; Fuchs, Sappho; Yébakima, André; Gustave, Joel; Girod, Romain; Dusfour, Isabelle; Leparc-Goffart, Isabelle; Vanlandingham, Dana L; Huang, Yan-Jang S; Lounibos, L Philip; Mohamed Ali, Souand; Nougairede, Antoine; de Lamballerie, Xavier; Failloux, Anna-Bella

2015-05-01

Chikungunya virus (CHIKV), mainly transmitted in urban areas by the mosquitoes Aedes aegypti and Aedes albopictus, constitutes a major public health problem. In late 2013, CHIKV emerged on Saint-Martin Island in the Caribbean and spread throughout the region reaching more than 40 countries. Thus far, Ae. aegypti mosquitoes have been implicated as the sole vector in the outbreaks, leading to the hypothesis that CHIKV spread could be limited only to regions where this mosquito species is dominant. We determined the ability of local populations of Ae. aegypti and Ae. albopictus from the Americas and Europe to transmit the CHIKV strain of the Asian genotype isolated from Saint-Martin Island (CHIKV_SM) during the recent epidemic, and an East-Central-South African (ECSA) genotype CHIKV strain isolated from La Réunion Island (CHIKV_LR) as a well-characterized control virus. We also evaluated the effect of temperature on transmission of CHIKV_SM by European Ae. albopictus. We found that (i) Aedes aegypti from Saint-Martin Island transmit CHIKV_SM and CHIKV_LR with similar efficiency, (ii) Ae. aegypti from the Americas display similar transmission efficiency for CHIKV_SM, (iii) American and European populations of the alternative vector species Ae. albopictus were as competent as Ae. aegypti populations with respect to transmission of CHIKV_SM and (iv) exposure of European Ae. albopictus to low temperatures (20°C) significantly reduced the transmission potential for CHIKV_SM. CHIKV strains belonging to the ECSA genotype could also have initiated local transmission in the new world. Additionally, the ongoing CHIKV outbreak in the Americas could potentially spread throughout Ae. aegypti- and Ae. albopictus-infested regions of the Americas with possible imported cases of CHIKV to Ae. albopictus-infested regions in Europe. Colder temperatures may decrease the local transmission of CHIKV_SM by European Ae. albopictus, potentially explaining the lack of autochthonous

Chikungunya Virus Transmission Potential by Local Aedes Mosquitoes in the Americas and Europe

PubMed Central

Vega-Rúa, Anubis; Lourenço-de-Oliveira, Ricardo; Mousson, Laurence; Vazeille, Marie; Fuchs, Sappho; Yébakima, André; Gustave, Joel; Girod, Romain; Dusfour, Isabelle; Leparc-Goffart, Isabelle; Vanlandingham, Dana L.; Huang, Yan-Jang S.; Lounibos, L. Philip; Mohamed Ali, Souand; Nougairede, Antoine; de Lamballerie, Xavier; Failloux, Anna-Bella

2015-01-01

Background Chikungunya virus (CHIKV), mainly transmitted in urban areas by the mosquitoes Aedes aegypti and Aedes albopictus, constitutes a major public health problem. In late 2013, CHIKV emerged on Saint-Martin Island in the Caribbean and spread throughout the region reaching more than 40 countries. Thus far, Ae. aegypti mosquitoes have been implicated as the sole vector in the outbreaks, leading to the hypothesis that CHIKV spread could be limited only to regions where this mosquito species is dominant. Methodology/Principal Findings We determined the ability of local populations of Ae. aegypti and Ae. albopictus from the Americas and Europe to transmit the CHIKV strain of the Asian genotype isolated from Saint-Martin Island (CHIKV_SM) during the recent epidemic, and an East-Central-South African (ECSA) genotype CHIKV strain isolated from La Réunion Island (CHIKV_LR) as a well-characterized control virus. We also evaluated the effect of temperature on transmission of CHIKV_SM by European Ae. albopictus. We found that (i) Aedes aegypti from Saint-Martin Island transmit CHIKV_SM and CHIKV_LR with similar efficiency, (ii) Ae. aegypti from the Americas display similar transmission efficiency for CHIKV_SM, (iii) American and European populations of the alternative vector species Ae. albopictus were as competent as Ae. aegypti populations with respect to transmission of CHIKV_SM and (iv) exposure of European Ae. albopictus to low temperatures (20°C) significantly reduced the transmission potential for CHIKV_SM. Conclusions/Significance CHIKV strains belonging to the ECSA genotype could also have initiated local transmission in the new world. Additionally, the ongoing CHIKV outbreak in the Americas could potentially spread throughout Ae. aegypti- and Ae. albopictus-infested regions of the Americas with possible imported cases of CHIKV to Ae. albopictus-infested regions in Europe. Colder temperatures may decrease the local transmission of CHIKV_SM by European Ae

Ecological Potential for Rabies Virus Transmission via Scavenging of Dead Bats by Mesocarnivores.

PubMed

Theimer, Tad C; Dyer, Annie C; Keeley, Brian W; Gilbert, Amy T; Bergman, David L

2017-04-01

Multiple species of bats are reservoirs of rabies virus in the Americas and are occasionally the source of spillover infections into mesocarnivore species. Although rabies transmission generally is assumed to occur via bite, laboratory studies have demonstrated the potential for rabies transmission via ingestion of rabid animals. We investigated the ecological potential for this mode of transmission by assessing mesocarnivore scavenging behavior of dead bats in suburban habitats of Flagstaff, Arizona, US. In autumn 2013, summer 2014, and autumn 2015, we placed 104 rabies-negative bat carcasses either near buildings, in wildland areas, or in residential yards and then monitored them with trail cameras for 5 d. Overall, 52 (50%) bat carcasses were scavenged, with 39 (75%) of those scavenged by striped skunks ( Mephitis mephitis ). Within our study area, striped skunks had a higher ecological potential to contract rabies via ingestion of bat carcasses compared to other mesocarnivore species, due both to a greater number of encounters and a higher probability of ingestion per encounter (91%), and they were significantly more likely to approach bat carcasses in yards than in wildland areas. Raccoons ( Procyon lotor ) and gray foxes ( Urocyon cinereoargenteus ) had fewer encounters (nine and 13, respectively) and lower probability of ingesting bats (33% and 8%, respectively).

Evaluation of the Potential Risk of Hepatitis B Virus Transmission in Skin Allografting.

PubMed

Wang, D; Xie, W; Chen, T; Dong, C; Zhao, C; Tan, H; Tian, H; Xie, Q

2015-01-01

Skin transplantation is associated with potential risk of infectious disease transmission; however, the exclusion of donors owing to hepatitis B virus (HBV) infection will worsen the shortage of allograft skin supply. We report a paired study to evaluate the potential risk of HBV transmission in skin allografting. The presence of HBV DNA in the serum and skin from 37 burn patients with chronic HBV infection (CHB) was monitored by a HBV polymerase chain reaction (PCR) and the positive rates were compared by Fisher's exact probability test. There was a high consistency in the HBV serology profile between HBV DNA PCR (83.78%) and the clinical HBV test. Only 2 patients who were positive for hepatitis B surface antigen, hepatitis B e antigen, and hepatitis B core antibody had detectable HBV DNA in the skin tissue; however, no hepatitis B surface antigen was detected as examined by immunohistochemistry staining. There was a significant difference between the positive rates of HBV DNA in the serum and skin (χc(2) = 27.03; P < .001). The potential risk for HBV transmission by skin allografting is very low. Given that China has a large population of patients with HBV, the acceptance of skin from donors with CHB to the skin bank would increase the number of tissue donations to meet the urgent medical need for skin transplantation. Copyright © 2015 Elsevier Inc. All rights reserved.

Potential distribution of mosquito vector species in a primary malaria endemic region of Colombia

PubMed Central

Altamiranda-Saavedra, Mariano; Arboleda, Sair; Parra, Juan L.; Peterson, A. Townsend

2017-01-01

Rapid transformation of natural ecosystems changes ecological conditions for important human disease vector species; therefore, an essential task is to identify and understand the variables that shape distributions of these species to optimize efforts toward control and mitigation. Ecological niche modeling was used to estimate the potential distribution and to assess hypotheses of niche similarity among the three main malaria vector species in northern Colombia: Anopheles nuneztovari, An. albimanus, and An. darlingi. Georeferenced point collection data and remotely sensed, fine-resolution satellite imagery were integrated across the Urabá –Bajo Cauca–Alto Sinú malaria endemic area using a maximum entropy algorithm. Results showed that An. nuneztovari has the widest geographic distribution, occupying almost the entire study region; this niche breadth is probably related to the ability of this species to colonize both, natural and disturbed environments. The model for An. darlingi showed that most suitable localities for this species in Bajo Cauca were along the Cauca and Nechí river. The riparian ecosystems in this region and the potential for rapid adaptation by this species to novel environments, may favor the establishment of populations of this species. Apparently, the three main Colombian Anopheles vector species in this endemic area do not occupy environments either with high seasonality, or with low seasonality and high NDVI values. Estimated overlap in geographic space between An. nuneztovari and An. albimanus indicated broad spatial and environmental similarity between these species. An. nuneztovari has a broader niche and potential distribution. Dispersal ability of these species and their ability to occupy diverse environmental situations may facilitate sympatry across many environmental and geographic contexts. These model results may be useful for the design and implementation of malaria species-specific vector control interventions optimized

Stratifying the potential local transmission of Zika in municipalities of Antioquia, Colombia.

PubMed

Ospina, Juan; Hincapie-Palacio, Doracelly; Ochoa, Jesús; Molina, Adriana; Rúa, Guillermo; Pájaro, Dubán; Arrubla, Marcela; Almanza, Rita; Paredes, Marlio; Mubayi, Anuj

2017-10-01

To stratify and understand the potential transmission processes of Zika virus in Colombia, in order to effectively address the efforts on surveillance and disease control. We compare R 0 of Zika for municipalities based on data from the regional surveillance system of Antioquia, Colombia. The basic reproduction number (R 0 ) and its 95% confidence intervals were estimated from an SIR model with implicit vector dynamics, in terms of recovered individuals in each time unit, using an approximate solution. These parameters were estimated fitting the solution of the model to the daily cumulative frequency of each Zika case according to symptoms onset date relative to the index case reported to the local surveillance system. R 0 was estimated for 20 municipalities with a median of 30 000 inhabitants, all located less than 2200 m above sea level. The reported cases ranged from 17 to 347 between these municipalities within 4 months (January to April of 2016). The results suggest that 15 municipalities had a high transmission potential (R 0  > 1), whereas in five municipality transmissions were potentially not sustaining (R 0  < 1), although the upper bound of the confidence interval of the R 0 for 3 of these 5 was greater than one, indicating the possibility of an outbreak later on. The study identified high-risk municipalities (R 0  > 1) and provide a technique to optimise surveillance and control of Zika. Health authorities should promote the collection, analysis, modelling and sharing of anonymous data onto individual cases to estimate R 0 . © 2017 John Wiley & Sons Ltd.

The potential for fungal biopesticides to reduce malaria transmission under diverse environmental conditions.

PubMed

Heinig, R L; Paaijmans, Krijn P; Hancock, Penelope A; Thomas, Matthew B

2015-12-01

The effectiveness of conventional malaria vector control is being threatened by the spread of insecticide resistance. One promising alternative to chemicals is the use of naturally-occurring insect-killing fungi. Numerous laboratory studies have shown that isolates of fungal pathogens such as Beauveria bassiana can infect and kill adult mosquitoes, including those resistant to chemical insecticides.Unlike chemical insecticides, fungi may take up to a week or more to kill mosquitoes following exposure. This slow kill speed can still reduce malaria transmission because the malaria parasite itself takes at least eight days to complete its development within the mosquito. However, both fungal virulence and parasite development rate are strongly temperature-dependent, so it is possible that biopesticide efficacy could vary across different transmission environments.We examined the virulence of a candidate fungal isolate against two key malaria vectors at temperatures from 10-34 °C. Regardless of temperature, the fungus killed more than 90% of exposed mosquitoes within the predicted duration of the malarial extrinsic incubation period, a result that was robust to realistic diurnal temperature variation.We then incorporated temperature sensitivities of a suite of mosquito, parasite and fungus life-history traits that are important determinants of malaria transmission into a stage-structured malaria transmission model. The model predicted that, at achievable daily fungal infection rates, fungal biopesticides have the potential to deliver substantial reductions in the density of malaria-infectious mosquitoes across all temperatures representative of malaria transmission environments. Synthesis and applications . Our study combines empirical data and theoretical modelling to prospectively evaluate the potential of fungal biopesticides to control adult malaria vectors. Our results suggest that Beauveria bassiana could be a potent tool for malaria control and support further

Sugar epitopes as potential universal disease transmission blocking targets.

PubMed

Dinglasan, Rhoel R; Valenzuela, Jesús G; Azad, Abdu F

2005-01-01

One promising method to prevent vector-borne diseases is through the use of transmission blocking vaccines (TBVs). However, developing several anti-pathogen TBVs may be impractical. In this study, we have identified a conserved candidate carbohydrate target in the midguts of several Arthropod vectors. A screen of the novel GlycoChip glycan array found that the anti-carbohydrate malaria transmission blocking monoclonal antibody (MG96) preferentially recognized D-mannose (alpha) and the type II lactosamine disaccharide. The specificity for D-mannose was confirmed by competition ELISA using alpha-methyl mannoside as inhibitor. Con A, which identifies terminal mannose residues, did not inhibit MG96 reactivity with mosquito midgut lysates, suggesting that Con A has differential recognition of this monosaccharide. However, the jack bean lectin, Jacalin, which recognizes D-mannose (alpha), d-galactose (alpha/beta) and the T antigen, not only displays a similar banding profile to that recognized by MG96 on immunoblot but was also shown to effectively inhibit MG96. Wheat-germ agglutinin, which recognizes N-acetyllactosamine units, only partially inhibited MG96 reactivity. This highlights the contribution of both glycan moieties to the MG96 epitope or glycotope. Enzyme deglycosylation results suggest that MG96 recognizes a mannose alpha1-6 substitution on an O-linked oligosaccharide. Taken together, the data suggest that MG96 recognizes a discontinuous glycotope composed of Manalpha1-6 proximal to Galbeta1-4GlcNAc-alpha-O-R glycans on arthropod vector midguts. As such, these glycotopes may represent potential transmission blocking vaccine targets for a wide range of vector-borne pathogens.

Molecular basis of mammalian transmissibility of avian H1N1 influenza viruses and their pandemic potential

PubMed Central

Zanin, Mark; Wong, Sook-San; Barman, Subrata; Kaewborisuth, Challika; Vogel, Peter; Rubrum, Adam; Darnell, Daniel; Marinova-Petkova, Atanaska; Krauss, Scott; Webby, Richard J.; Webster, Robert G.

2017-01-01

North American wild birds are an important reservoir of influenza A viruses, yet the potential of viruses in this reservoir to transmit and cause disease in mammals is not well understood. Our surveillance of avian influenza viruses (AIVs) at Delaware Bay, USA, revealed a group of similar H1N1 AIVs isolated in 2009, some of which were airborne-transmissible in the ferret model without prior adaptation. Comparison of the genomes of these viruses revealed genetic markers of airborne transmissibility in the Polymerase Basic 2 (PB2), PB1, PB1-F2, Polymerase Acidic-X (PA-X), Nonstructural Protein 1 (NS1), and Nuclear Export Protein (NEP) genes. We studied the role of NS1 in airborne transmission and found that NS1 mutants that were not airborne-transmissible caused limited tissue pathology in the upper respiratory tract (URT). Viral maturation was also delayed, evident as strong intranuclear staining and little virus at the mucosa. Our study of this naturally occurring constellation of genetic markers has provided insights into the poorly understood phenomenon of AIV airborne transmissibility by revealing a role for NS1 and characteristics of viral replication in the URT that were associated with airborne transmission. The transmissibility of these viruses further highlights the pandemic potential of AIVs in the wild bird reservoir and the need to maintain surveillance. PMID:28874549

Mapping influenza transmission in the ferret model to transmission in humans

PubMed Central

Buhnerkempe, Michael G; Gostic, Katelyn; Park, Miran; Ahsan, Prianna; Belser, Jessica A; Lloyd-Smith, James O

2015-01-01

The controversy surrounding 'gain-of-function' experiments on high-consequence avian influenza viruses has highlighted the role of ferret transmission experiments in studying the transmission potential of novel influenza strains. However, the mapping between influenza transmission in ferrets and in humans is unsubstantiated. We address this gap by compiling and analyzing 240 estimates of influenza transmission in ferrets and humans. We demonstrate that estimates of ferret secondary attack rate (SAR) explain 66% of the variation in human SAR estimates at the subtype level. Further analysis shows that ferret transmission experiments have potential to identify influenza viruses of concern for epidemic spread in humans, though small sample sizes and biological uncertainties prevent definitive classification of human transmissibility. Thus, ferret transmission experiments provide valid predictions of pandemic potential of novel influenza strains, though results should continue to be corroborated by targeted virological and epidemiological research. DOI: http://dx.doi.org/10.7554/eLife.07969.001 PMID:26329460

Evaluation of the zoonotic potential of transmissible mink encephalopathy

USDA-ARS?s Scientific Manuscript database

Successful transmission of Transmissible Mink Encephalopathy (TME) to cattle supports the bovine hypothesis to the still controversial origin of TME outbreaks. Human and primate susceptibility to classical Bovine Spongiform Encephalopathy (c-BSE) and the transmissibility of L-type BSE to macaques as...

Automobile windshield washer fluid: A potential source of transmission for Legionella.

PubMed

Schwake, David Otto; Alum, Absar; Abbaszadegan, Morteza

2015-09-01

Epidemiological evidence suggesting driving cars to be a risk factor for legionellosis has prompted public health studies to investigate vehicle windshield washer fluid as a novel transmission source of this disease. The goal of the current study was to investigate whether or not windshield washer fluid could serve as a potential source of transmission for Legionella. A wide variation in the survival of L. pneumophila was observed when incubated in different washer fluids at 25 and 37 °C, however, one brand tested supported Legionella survival similar to or greater than sterilized deionized water. In addition, 1 L of tap water contained in a washer fluid reservoir was able to support population growth and survival of Legionella for several months. In a field study examining the windshield washer fluid of 12 elementary school buses, Legionella were detected from 84% of samples at a high concentration of 8.1×10(4) CFU/mL. Culturable cells were also detected in aerosolized washer fluid during washer fluid spray. By demonstrating survival in certain windshield washer fluids, growth within washer fluid reservoirs, and the presence of viable cells in bus washer fluid spray, we have provided evidence suggesting the potential for a novel route of Legionella exposure. Copyright © 2015 Elsevier B.V. All rights reserved.

Potential for Zika Virus to Establish a Sylvatic Transmission Cycle in the Americas

PubMed Central

Althouse, Benjamin M.; Vasilakis, Nikos; Sall, Amadou A.; Diallo, Mawlouth; Weaver, Scott C.; Hanley, Kathryn A.

2016-01-01

Zika virus (ZIKV) originated and continues to circulate in a sylvatic transmission cycle between non-human primate hosts and arboreal mosquitoes in tropical Africa. Recently ZIKV invaded the Americas, where it poses a threat to human health, especially to pregnant women and their infants. Here we examine the risk that ZIKV will establish a sylvatic cycle in the Americas, focusing on Brazil. We review the natural history of sylvatic ZIKV and present a mathematical dynamic transmission model to assess the probability of establishment of a sylvatic ZIKV transmission cycle in non-human primates and/or other mammals and arboreal mosquito vectors in Brazil. Brazil is home to multiple species of primates and mosquitoes potentially capable of ZIKV transmission, though direct assessment of host competence (ability to mount viremia sufficient to infect a feeding mosquito) and vector competence (ability to become infected with ZIKV and disseminate and transmit upon subsequent feedings) of New World species is lacking. Modeling reveals a high probability of establishment of sylvatic ZIKV across a large range of biologically plausible parameters. Probability of establishment is dependent on host and vector population sizes, host birthrates, and ZIKV force of infection. Research on the host competence of New World monkeys or other small mammals to ZIKV, on vector competence of New World Aedes, Sabethes, and Haemagogus mosquitoes for ZIKV, and on the geographic range of potential New World hosts and vectors is urgently needed. A sylvatic cycle of ZIKV would make future elimination efforts in the Americas practically impossible, and paints a dire picture for the epidemiology of ZIKV and our ability to end the ongoing outbreak of congenital Zika syndrome. PMID:27977671

Potential for Zika Virus to Establish a Sylvatic Transmission Cycle in the Americas.

PubMed

Althouse, Benjamin M; Vasilakis, Nikos; Sall, Amadou A; Diallo, Mawlouth; Weaver, Scott C; Hanley, Kathryn A

2016-12-01

Zika virus (ZIKV) originated and continues to circulate in a sylvatic transmission cycle between non-human primate hosts and arboreal mosquitoes in tropical Africa. Recently ZIKV invaded the Americas, where it poses a threat to human health, especially to pregnant women and their infants. Here we examine the risk that ZIKV will establish a sylvatic cycle in the Americas, focusing on Brazil. We review the natural history of sylvatic ZIKV and present a mathematical dynamic transmission model to assess the probability of establishment of a sylvatic ZIKV transmission cycle in non-human primates and/or other mammals and arboreal mosquito vectors in Brazil. Brazil is home to multiple species of primates and mosquitoes potentially capable of ZIKV transmission, though direct assessment of host competence (ability to mount viremia sufficient to infect a feeding mosquito) and vector competence (ability to become infected with ZIKV and disseminate and transmit upon subsequent feedings) of New World species is lacking. Modeling reveals a high probability of establishment of sylvatic ZIKV across a large range of biologically plausible parameters. Probability of establishment is dependent on host and vector population sizes, host birthrates, and ZIKV force of infection. Research on the host competence of New World monkeys or other small mammals to ZIKV, on vector competence of New World Aedes, Sabethes, and Haemagogus mosquitoes for ZIKV, and on the geographic range of potential New World hosts and vectors is urgently needed. A sylvatic cycle of ZIKV would make future elimination efforts in the Americas practically impossible, and paints a dire picture for the epidemiology of ZIKV and our ability to end the ongoing outbreak of congenital Zika syndrome.

Personal clothing as a potential vector of respiratory virus transmission in childcare settings.

PubMed

Gralton, Jan; McLaws, Mary-Louise; Rawlinson, William D

2015-06-01

Previous investigations of fomite transmission have focused on the presence of pathogens on inanimate objects in clinical settings. There has been limited investigation of fomite transmission in non-clinical pediatric settings where there is a high prevalence of respiratory virus infections. Over a 5 week period, this study investigated whether the personal clothing of teachers working in childcare centers was contaminated with viral RNA, and potentially could mediate virus transmission. Matched morning and evening clothing and nasal samples were collected for 313 teacher work days (TWDs). Human rhinoviruses (hRV) RNA were detected from samples using real-time PCR. Human rhinovirus RNA was detected in clothing samples on 16 TWDs and in nasal samples on 32 TWDs. There were no TWDs when teachers provided both positive nasal and clothing samples and only three TWDs when hRV persisted on clothing for the entire day. The detection of hRV RNA was significantly predicted by self-recognition of symptomatic illness by the teacher 2 days prior to detection. These findings suggest that teachers' personal clothing in childcare settings is unlikely to facilitate the transmission of hRV. © 2015 Wiley Periodicals, Inc.

Diffraction and Transmission Synchrotron Imaging at the German Light Source ANKA--Potential Industrial Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rack, Alexander; Weitkamp, Timm; European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex

2009-03-10

Diffraction and transmission synchrotron imaging methods have proven to be highly suitable for investigations in materials research and non-destructive evaluation. The high flux and spatial coherence of X-rays from modern synchrotron light sources allows one to work using high resolution and different contrast modalities. This article gives a short overview of different transmission and diffraction imaging methods with high potential for industrial applications, now available for commercial access via the German light source ANKA (Forschungszentrum Karlsruhe) and its new department ANKA Commercial Service (ANKA COS, http://www.anka-cos.de)

Abundance, biting behaviour and parous rate of anopheline mosquito species in relation to malaria incidence in gold-mining areas of southern Venezuela.

PubMed

Moreno, J E; Rubio-Palis, Y; Páez, E; Pérez, E; Sánchez, V

2007-12-01

A longitudinal entomological and epidemiological study was conducted in five localities of southern Venezuela between January 1999 and April 2000 to determine the abundance, biting behaviour and parity of anopheline mosquitoes (Diptera: Culicidae) in relation to climate variables and malaria incidence. A total of 3685 female anopheline mosquitoes, representing six species, were collected. The most abundant species were Anopheles marajoara Galvão & Damasceno (60.7%) and Anopheles darlingi Root (35.1%), which together represented 95.8% of the total anophelines collected. Abundance and species distribution varied by locality. Malaria prevalence varied from 12.5 to 21.4 cases per 1000 population. Transmission occurred throughout the year; the annual parasite index (API) for the study period was 813.0 cases per 1000 population, with a range of 71.6-2492 per 1000 population, depending on locality. Plasmodium vivax (Grassi & Feletti) (Coccidia: Plasmodiidae) accounted for 78.6% of cases, Plasmodium falciparum (Welch) for 21.4% and mixed infections (Pv+Pf) for < 0.1%. Anopheles marajoara and An. darlingi were more abundant during the rainy season (April-September). There was no significant correlation (P > 0.05) between mosquito abundance and rainfall. Correlations between malaria incidence by parasite species and mosquito abundance were not significant (P > 0.05). Monthly parous rates were similar for An. marajoara and An. darlingi throughout the year, with two peaks that coincided with the dry-rainy transition period and the period of less rain. Peaks in the incidence of malaria cases were observed 1 month after major peaks in biting rates of parous anophelines. Anopheles darlingi engages in biting activity throughout the night, with two minor peaks at 23.00-00.00 hours and 03.00-04.00 hours. Anopheles marajoara has a different pattern, with a biting peak at 19.00-21.00 hours and 76.6% of biting occurring before midnight. Although both vectors bite indoors and outdoors

Potential of laser for SPS power transmission

NASA Technical Reports Server (NTRS)

Bain, C. N.

1978-01-01

Research on the feasibility of using a laser subsystem as an additional option for the transmission of the satellite power system (STS) power is presented. Current laser work and predictions for future laser performance provide a level of confidence that the development of a laser power transmission system is technologically feasible in the time frame required to develop the SBS. There are significant economic advantages in lower ground distribution costs and a reduction of more than two orders of magnitude in real estate requirements for ground based receiving/conversion sites.

Potential Impact of Sexual Transmission on Ebola Virus Epidemiology: Sierra Leone as a Case Study.

PubMed

Abbate, Jessica L; Murall, Carmen Lia; Richner, Heinz; Althaus, Christian L

2016-05-01

Sexual transmission of Ebola virus disease (EVD) 6 months after onset of symptoms has been recently documented, and Ebola virus RNA has been detected in semen of survivors up to 9 months after onset of symptoms. As countries affected by the 2013-2015 epidemic in West Africa, by far the largest to date, are declared free of Ebola virus disease (EVD), it remains unclear what threat is posed by rare sexual transmission events that could arise from survivors. We devised a compartmental mathematical model that includes sexual transmission from convalescent survivors: a SEICR (susceptible-exposed-infectious-convalescent-recovered) transmission model. We fitted the model to weekly incidence of EVD cases from the 2014-2015 epidemic in Sierra Leone. Sensitivity analyses and Monte Carlo simulations showed that a 0.1% per sex act transmission probability and a 3-month convalescent period (the two key unknown parameters of sexual transmission) create very few additional cases, but would extend the epidemic by 83 days [95% CI: 68-98 days] (p < 0.0001) on average. Strikingly, a 6-month convalescent period extended the average epidemic by 540 days (95% CI: 508-572 days), doubling the current length, despite an insignificant rise in the number of new cases generated. Our results show that reductions in the per sex act transmission probability via abstinence and condom use should reduce the number of sporadic sexual transmission events, but will not significantly reduce the epidemic size and may only minimally shorten the length of time the public health community must maintain response preparedness. While the number of infectious survivors is expected to greatly decline over the coming months, our results show that transmission events may still be expected for quite some time as each event results in a new potential cluster of non-sexual transmission. Precise measurement of the convalescent period is thus important for planning ongoing surveillance efforts.

Mapping Potential Amplification and Transmission Hotspots for MERS-CoV, Kenya.

PubMed

Gikonyo, Stephen; Kimani, Tabitha; Matere, Joseph; Kimutai, Joshua; Kiambi, Stella G; Bitek, Austine O; Juma Ngeiywa, K J Z; Makonnen, Yilma J; Tripodi, Astrid; Morzaria, Subhash; Lubroth, Juan; Rugalema, Gabriel; Fasina, Folorunso Oludayo

2018-03-16

Dromedary camels have been implicated consistently as the source of Middle East respiratory syndrome coronavirus (MERS-CoV) human infections and attention to prevent and control it has focused on camels. To understanding the epidemiological role of camels in the transmission of MERS-CoV, we utilized an iterative empirical process in Geographic Information System (GIS) to identify and qualify potential hotspots for maintenance and circulation of MERS-CoV, and produced risk-based surveillance sites in Kenya. Data on camel population and distribution were used to develop camel density map, while camel farming system was defined using multi-factorial criteria including the agro-ecological zones (AEZs), production and marketing practices. Primary and secondary MERS-CoV seroprevalence data from specific sites were analyzed, and location-based prevalence matching with camel densities was conducted. High-risk convergence points (migration zones, trade routes, camel markets, slaughter slabs) were profiled and frequent cross-border camel movement mapped. Results showed that high camel-dense areas and interaction (markets and migration zones) were potential hotspot for transmission and spread. Cross-border contacts occurred with in-migrated herds at hotspot locations. AEZ differential did not influence risk distribution and plausible risk factors for spatial MERS-CoV hotspots were camel densities, previous cases of MERS-CoV, high seroprevalence and points of camel convergences. Although Kenyan camels are predisposed to MERS-CoV, no shedding is documented to date. These potential hotspots, determined using anthropogenic, system and trade characterizations should guide selection of sampling/surveillance sites, high-risk locations, critical areas for interventions and policy development in Kenya, as well as instigate further virological examination of camels.

Preliminary Biological Studies on Larvae and Adult Anopheles Mosquitoes (Diptera: Culicidae) in Miraflores, a Malaria Endemic Locality in Guaviare Department, Amazonian Colombia

PubMed Central

JIMÉNEZ, IRENE P.; CONN, JAN E.; BROCHERO, HELENA

2015-01-01

In the malaria endemic municipality of Miraflores in southeastern Amazonian Colombia, several aspects of the biology of local Anopheles species were investigated to supplement the limited entomological surveillance information available and to provide baseline data for malaria prevention and vector control. Anopheles darlingi Root, 1926 was the most abundant species (95.6%), followed by Anopheles braziliensis (Chagas) (3.6%) and Anopheles oswaldoi s.l. (Peryassu) (0.7%). During the dry season, exophagic activity was prevalent only between 1800–2100 hours; after this (2100–0600 hours) only endophagy was encountered. In contrast, during the rainy season, both endophagy and exophagy occurred throughout the collection period. The human biting rate for An. darlingi was 8.6. This species was positive for Plasmodium vivax VK210 with a sporozoite rate = 0.13 (1/788). Breeding sites corresponded to stream (n = 7), flooded excavations (n = 4), flooded forest (n = 1), wetlands (n = 2), and an abandoned water reservoir (n = 1). An. darlingi predominated in these sites in both seasons. Based on these data, An. darlingi is the main local malaria vector, and we recommend that local prevention and control efforts focus on strengthening entomological surveillance to determine potential changes of species biting behavior and time to reduce human–vector interactions. PMID:25276930

Quantum Transmission Conditions for Diffusive Transport in Graphene with Steep Potentials

NASA Astrophysics Data System (ADS)

Barletti, Luigi; Negulescu, Claudia

2018-05-01

We present a formal derivation of a drift-diffusion model for stationary electron transport in graphene, in presence of sharp potential profiles, such as barriers and steps. Assuming the electric potential to have steep variations within a strip of vanishing width on a macroscopic scale, such strip is viewed as a quantum interface that couples the classical regions at its left and right sides. In the two classical regions, where the potential is assumed to be smooth, electron and hole transport is described in terms of semiclassical kinetic equations. The diffusive limit of the kinetic model is derived by means of a Hilbert expansion and a boundary layer analysis, and consists of drift-diffusion equations in the classical regions, coupled by quantum diffusive transmission conditions through the interface. The boundary layer analysis leads to the discussion of a four-fold Milne (half-space, half-range) transport problem.

Calculating the potential for within-flight transmission of influenza A (H1N1)

PubMed Central

2009-01-01

Background Clearly air travel, by transporting infectious individuals from one geographic location to another, significantly affects the rate of spread of influenza A (H1N1). However, the possibility of within-flight transmission of H1N1 has not been evaluated; although it is known that smallpox, measles, tuberculosis, SARS and seasonal influenza can be transmitted during commercial flights. Here we present the first quantitative risk assessment to assess the potential for within-flight transmission of H1N1. Methods We model airborne transmission of infectious viral particles of H1N1 within a Boeing 747 using methodology from the field of quantitative microbial risk assessment. Results The risk of catching H1N1 will essentially be confined to passengers travelling in the same cabin as the source case. Not surprisingly, we find that the longer the flight the greater the number of infections that can be expected. We calculate that H1N1, even during long flights, poses a low to moderate within-flight transmission risk if the source case travels First Class. Specifically, 0-1 infections could occur during a 5 hour flight, 1-3 during an 11 hour flight and 2-5 during a 17 hour flight. However, within-flight transmission could be significant, particularly during long flights, if the source case travels in Economy Class. Specifically, two to five infections could occur during a 5 hour flight, 5-10 during an 11 hour flight and 7-17 during a 17 hour flight. If the aircraft is only partially loaded, under certain conditions more infections could occur in First Class than in Economy Class. During a 17 hour flight, a greater number of infections would occur in First Class than in Economy if the First Class Cabin is fully occupied, but Economy class is less than 30% full. Conclusions Our results provide insights into the potential utility of air travel restrictions on controlling influenza pandemics in the winter of 2009/2010. They show travel by one infectious individual

Calculating the potential for within-flight transmission of influenza A (H1N1).

PubMed

Wagner, Bradley G; Coburn, Brian J; Blower, Sally

2009-12-24

Clearly air travel, by transporting infectious individuals from one geographic location to another, significantly affects the rate of spread of influenza A (H1N1). However, the possibility of within-flight transmission of H1N1 has not been evaluated; although it is known that smallpox, measles, tuberculosis, SARS and seasonal influenza can be transmitted during commercial flights. Here we present the first quantitative risk assessment to assess the potential for within-flight transmission of H1N1. We model airborne transmission of infectious viral particles of H1N1 within a Boeing 747 using methodology from the field of quantitative microbial risk assessment. The risk of catching H1N1 will essentially be confined to passengers travelling in the same cabin as the source case. Not surprisingly, we find that the longer the flight the greater the number of infections that can be expected. We calculate that H1N1, even during long flights, poses a low to moderate within-flight transmission risk if the source case travels First Class. Specifically, 0-1 infections could occur during a 5 hour flight, 1-3 during an 11 hour flight and 2-5 during a 17 hour flight. However, within-flight transmission could be significant, particularly during long flights, if the source case travels in Economy Class. Specifically, two to five infections could occur during a 5 hour flight, 5-10 during an 11 hour flight and 7-17 during a 17 hour flight. If the aircraft is only partially loaded, under certain conditions more infections could occur in First Class than in Economy Class. During a 17 hour flight, a greater number of infections would occur in First Class than in Economy if the First Class Cabin is fully occupied, but Economy class is less than 30% full. Our results provide insights into the potential utility of air travel restrictions on controlling influenza pandemics in the winter of 2009/2010. They show travel by one infectious individual, rather than causing a single outbreak of H1N

Transmission potential of Zika virus infection in the South Pacific.

PubMed

Nishiura, Hiroshi; Kinoshita, Ryo; Mizumoto, Kenji; Yasuda, Yohei; Nah, Kyeongah

2016-04-01

Zika virus has spread internationally through countries in the South Pacific and Americas. The present study aimed to estimate the basic reproduction number, R0, of Zika virus infection as a measurement of the transmission potential, reanalyzing past epidemic data from the South Pacific. Incidence data from two epidemics, one on Yap Island, Federal State of Micronesia in 2007 and the other in French Polynesia in 2013-2014, were reanalyzed. R0 of Zika virus infection was estimated from the early exponential growth rate of these two epidemics. The maximum likelihood estimate (MLE) of R0 for the Yap Island epidemic was in the order of 4.3-5.8 with broad uncertainty bounds due to the small sample size of confirmed and probable cases. The MLE of R0 for French Polynesia based on syndromic data ranged from 1.8 to 2.0 with narrow uncertainty bounds. The transmissibility of Zika virus infection appears to be comparable to those of dengue and chikungunya viruses. Considering that Aedes species are a shared vector, this finding indicates that Zika virus replication within the vector is perhaps comparable to dengue and chikungunya. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Most outdoor malaria transmission by behaviourally-resistant Anopheles arabiensis is mediated by mosquitoes that have previously been inside houses.

PubMed

Killeen, Gerry F; Govella, Nicodem J; Lwetoijera, Dickson W; Okumu, Fredros O

2016-04-19

in Africa and other important vectors of residual transmission across the tropics. Improved control of predominantly outdoor residual transmission by An. arabiensis, and other modestly zoophagic vectors like Anopheles darlingi, which frequently enter but then rapidly exit from houses, may be readily achieved by improving existing technology for killing mosquitoes indoors.

Investigation of a Sudden Malaria Outbreak in the Isolated Amazonian Village of Saül, French Guiana, January–April 2009

PubMed Central

Berger, Franck; Flamand, Claude; Musset, Lise; Djossou, Félix; Rosine, Jacques; Sanquer, Marie-Anne; Dusfour, Isabelle; Legrand, Eric; Ardillon, Vanessa; Rabarison, Patrick; Grenier, Claire; Girod, Romain

2012-01-01

Malaria is endemic in French Guiana. Plasmodium falciparum and Plasmodium vivax are the predominant species responsible and Anopheles darlingi is described as the major vector. In mid-August 2008, an increase in malaria incidence was observed in Saül. A retrospective cohort survey was performed. In vitro susceptibility profiles to antimalarials were determined on P. falciparum isolates. Collections of mosquitoes were organized. The malaria attack rate reached 70.6/100. The risk of malaria increased for people between 40 and 49 years of age, living in a house not subjected to a recent indoor residual insecticide spraying or staying overnight in the surrounding forest. All isolates were susceptible. Anopheles darlingi females and larvae were collected in the village suggesting a local transmission. Our results strongly support a role of illegal mining activities in the emergence of new foci of malaria. Therefore, public health authorities should define policies to fight malaria at a transborder level. PMID:22492141

Role of Gastropod Mucus in the Transmission of Angiostrongylus cantonensis, a Potentially Serious Neurological Infection.

PubMed

Kramer, Kenton J; Posner, Jourdan; Gosnell, William L

2018-04-18

Angiostrongylus cantonensis, the rat lungworm, is endemic to Hawaii. A recent increase in the number of cases has drawn intense local and national media attention. As a result there is an increased fear of acquiring the disease from local produce, which has the potential to adversely affect the income of local farmers. The most common means of transmission is by the ingestion of an infected intermediate host. Other modes of transmission have been suggested including infectious larvae being released into the mucus trail of gastropods. This literature review indicates that mucus trails from infected gastropods poses a minimal risk to humans.

Force transmissibility versus displacement transmissibility

NASA Astrophysics Data System (ADS)

Lage, Y. E.; Neves, M. M.; Maia, N. M. M.; Tcherniak, D.

2014-10-01

It is well-known that when a single-degree-of-freedom (sdof) system is excited by a continuous motion of the foundation, the force transmissibility, relating the force transmitted to the foundation to the applied force, equals the displacement transmissibility. Recent developments in the generalization of the transmissibility to multiple-degree-of-freedom (mdof) systems have shown that similar simple and direct relations between both types of transmissibility do not appear naturally from the definitions, as happens in the sdof case. In this paper, the authors present their studies on the conditions under which it is possible to establish a relation between force transmissibility and displacement transmissibility for mdof systems. As far as the authors are aware, such a relation is not currently found in the literature, which is justified by being based on recent developments in the transmissibility concept for mdof systems. Indeed, it does not appear naturally, but the authors observed that the needed link is present when the displacement transmissibility is obtained between the same coordinates where the applied and reaction forces are considered in the force transmissibility case; this implies that the boundary conditions are not exactly the same and instead follow some rules. This work presents a formal derivation of the explicit relation between the force and displacement transmissibilities for mdof systems, and discusses its potential and limitations. The authors show that it is possible to obtain the displacement transmissibility from measured forces, and the force transmissibility from measured displacements, opening new perspectives, for example, in the identification of applied or transmitted forces. With this novel relation, it becomes possible, for example, to estimate the force transmissibility matrix with the structure off its supports, in free boundary conditions, and without measuring the forces. As far as force identification is concerned, this

The potential for sexual transmission to compromise control of Ebola virus outbreaks.

PubMed

Vinson, John E; Drake, John M; Rohani, Pejman; Park, Andrew W

2016-06-01

Recent evidence suggests that sexual contact may give rise to transmission of Ebola virus long after infection has been cleared from blood. We develop a simple mathematical model that incorporates contact transmission and sexual transmission parametrized from data relating to the 2013-2015 West African Ebola epidemic. The model explores scenarios where contact transmission is reduced following infection events, capturing behaviour change, and quantifies how these actions reducing transmission may be compromised by sexual transmission in terms of increasing likelihood, size and duration of outbreaks. We characterize the extent to which sexual transmission operates in terms of the probability of initial infection resolving to sexual infectiousness and the sexual transmission rate, and relate these parameters to the overall case burden. We find that sexual transmission can have large effects on epidemic dynamics (increasing attack ratios from 25% in scenarios without sexual transmission but with contact-transmission-reducing behaviour, up to 80% in equivalent scenarios with sexual transmission). © 2016 The Author(s).

Transmission rights and market power

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bushnell, J.

1999-10-01

Most of the concerns about physical transmission rights relate to the ability to implicitly or explicitly remove that transmission capacity from the market-place. Under a very strict form of physical right, owners could simply choose not to sell it if they don't want to use it. Modifications that require the release of spare capacity back into an open market could potentially alleviate this problem but there is concern that such releases would not occur far enough in advance to be of much use to schedulers. Similarly, the transmission capacity that is made available for use by non-rights holders can alsomore » be manipulated by the owners of transmission rights. The alternative form, financial transmission rights, provide to their owners congestion payments, but physical control of transmission paths. In electricity markets such as California's, even financial transmission rights could potentially be utilized to effectively withhold transmission capacity from the marketplace. However, methods for withholding transmission capacity are somewhat more convoluted, and probably more difficult, for owners of financial rights than for owners of physical rights. In this article, the author discusses some of the potential concerns over transmission rights and their use for the exercise of various forms of market power.« less

Quantifying the effects of temperature on mosquito and parasite traits that determine the transmission potential of human malaria.

PubMed

Shapiro, Lillian L M; Whitehead, Shelley A; Thomas, Matthew B

2017-10-01

Malaria transmission is known to be strongly impacted by temperature. The current understanding of how temperature affects mosquito and parasite life history traits derives from a limited number of empirical studies. These studies, some dating back to the early part of last century, are often poorly controlled, have limited replication, explore a narrow range of temperatures, and use a mixture of parasite and mosquito species. Here, we use a single pairing of the Asian mosquito vector, An. stephensi and the human malaria parasite, P. falciparum to conduct a comprehensive evaluation of the thermal performance curves of a range of mosquito and parasite traits relevant to transmission. We show that biting rate, adult mortality rate, parasite development rate, and vector competence are temperature sensitive. Importantly, we find qualitative and quantitative differences to the assumed temperature-dependent relationships. To explore the overall implications of temperature for transmission, we first use a standard model of relative vectorial capacity. This approach suggests a temperature optimum for transmission of 29°C, with minimum and maximum temperatures of 12°C and 38°C, respectively. However, the robustness of the vectorial capacity approach is challenged by the fact that the empirical data violate several of the model's simplifying assumptions. Accordingly, we present an alternative model of relative force of infection that better captures the observed biology of the vector-parasite interaction. This model suggests a temperature optimum for transmission of 26°C, with a minimum and maximum of 17°C and 35°C, respectively. The differences between the models lead to potentially divergent predictions for the potential impacts of current and future climate change on malaria transmission. The study provides a framework for more detailed, system-specific studies that are essential to develop an improved understanding on the effects of temperature on malaria

Predicting the potential environmental suitability for Theileria orientalis transmission in New Zealand cattle using maximum entropy niche modelling.

PubMed

Lawrence, K E; Summers, S R; Heath, A C G; McFadden, A M J; Pulford, D J; Pomroy, W E

2016-07-15

The tick-borne haemoparasite Theileria orientalis is the most important infectious cause of anaemia in New Zealand cattle. Since 2012 a previously unrecorded type, T. orientalis type 2 (Ikeda), has been associated with disease outbreaks of anaemia, lethargy, jaundice and deaths on over 1000 New Zealand cattle farms, with most of the affected farms found in the upper North Island. The aim of this study was to model the relative environmental suitability for T. orientalis transmission throughout New Zealand, to predict the proportion of cattle farms potentially suitable for active T. orientalis infection by region, island and the whole of New Zealand and to estimate the average relative environmental suitability per farm by region, island and the whole of New Zealand. The relative environmental suitability for T. orientalis transmission was estimated using the Maxent (maximum entropy) modelling program. The Maxent model predicted that 99% of North Island cattle farms (n=36,257), 64% South Island cattle farms (n=15,542) and 89% of New Zealand cattle farms overall (n=51,799) could potentially be suitable for T. orientalis transmission. The average relative environmental suitability of T. orientalis transmission at the farm level was 0.34 in the North Island, 0.02 in the South Island and 0.24 overall. The study showed that the potential spatial distribution of T. orientalis environmental suitability was much greater than presumed in the early part of the Theileria associated bovine anaemia (TABA) epidemic. Maximum entropy offers a computer efficient method of modelling the probability of habitat suitability for an arthropod vectored disease. This model could help estimate the boundaries of the endemically stable and endemically unstable areas for T. orientalis transmission within New Zealand and be of considerable value in informing practitioner and farmer biosecurity decisions in these respective areas. Copyright © 2016 Elsevier B.V. All rights reserved.

Control of somatic membrane potential in nociceptive neurons and its implications for peripheral nociceptive transmission

PubMed Central

Du, Xiaona; Hao, Han; Gigout, Sylvain; Huang, Dongyang; Yang, Yuehui; Li, Li; Wang, Caixue; Sundt, Danielle; Jaffe, David B.; Zhang, Hailin; Gamper, Nikita

2014-01-01

Peripheral sensory ganglia contain somata of afferent fibres conveying somatosensory inputs to the central nervous system. Growing evidence suggests that the somatic/perisomatic region of sensory neurons can influence peripheral sensory transmission. Control of resting membrane potential (Erest) is an important mechanism regulating excitability, but surprisingly little is known about how Erest is regulated in sensory neuron somata or how changes in somatic/perisomatic Erest affect peripheral sensory transmission. We first evaluated the influence of several major ion channels on Erest in cultured small-diameter, mostly capsaicin-sensitive (presumed nociceptive) dorsal root ganglion (DRG) neurons. The strongest and most prevalent effect on Erest was achieved by modulating M channels, K2P and 4-aminopiridine-sensitive KV channels, while hyperpolarization-activated cyclic nucleotide-gated, voltage-gated Na+, and T-type Ca2+ channels to a lesser extent also contributed to Erest. Second, we investigated how varying somatic/perisomatic membrane potential, by manipulating ion channels of sensory neurons within the DRG, affected peripheral nociceptive transmission in vivo. Acute focal application of M or KATP channel enhancers or a hyperpolarization-activated cyclic nucleotide-gated channel blocker to L5 DRG in vivo significantly alleviated pain induced by hind paw injection of bradykinin. Finally, we show with computational modelling how somatic/perisomatic hyperpolarization, in concert with the low-pass filtering properties of the t-junction within the DRG, can interfere with action potential propagation. Our study deciphers a complement of ion channels that sets the somatic Erest of nociceptive neurons and provides strong evidence for a robust filtering role of the somatic and perisomatic compartments of peripheral nociceptive neuron. PMID:25168672

Electricity Transmission, Pipelines, and National Trails: An Analysis of Current and Potential Intersections on Federal Lands in the Eastern United States, Alaska, and Hawaii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuiper, James A.; Krummel, John R.; Hlava, Kevin J.

As has been noted in many reports and publications, acquiring new or expanded rights-of-way for transmission is a challenging process, because numerous land use and land ownership constraints must be overcome to develop pathways suitable for energy transmission infrastructure. In the eastern U.S., more than twenty federally protected national trails (some of which are thousands of miles long, and cross many states) pose a potential obstacle to the development of new or expanded electricity transmission capacity. However, the scope of this potential problem is not well-documented, and there is no baseline information available that could allow all stakeholders to studymore » routing scenarios that could mitigate impacts on national trails. This report, Electricity Transmission, Pipelines, and National Trails: An Analysis of Current and Potential Intersections on Federal Lands in the Eastern United States, was prepared by the Environmental Science Division of Argonne National Laboratory (Argonne). Argonne was tasked by DOE to analyze the “footprint” of the current network of National Historic and Scenic Trails and the electricity transmission system in the 37 eastern contiguous states, Alaska, and Hawaii; assess the extent to which national trails are affected by electrical transmission; and investigate the extent to which national trails and other sensitive land use types may be affected in the near future by planned transmission lines. Pipelines are secondary to transmission lines for analysis, but are also within the analysis scope in connection with the overall directives of Section 368 of the Energy Policy Act of 2005, and because of the potential for electrical transmission lines being collocated with pipelines.« less

Potentiation of Schaffer-Collateral CA1 Synaptic Transmission by eEF2K and p38 MAPK Mediated Mechanisms.

PubMed

Weng, Weiguang; Chen, Ying; Wang, Man; Zhuang, Yinghan; Behnisch, Thomas

2016-01-01

The elongation factor 2 kinase (eEF2K), likewise known as CaMKIII, has been demonstrated to be involved in antidepressant responses of NMDA receptor antagonists. Even so, it remains open whether direct inhibition of eEF2K without altering up-stream or other signaling pathways affects hippocampal synaptic transmission and neuronal network synchrony. Inhibition of eEF2K by the selective and potent eEF2K inhibitor A-484954 induced a fast pre-synaptically mediated enhancement of synaptic transmission and synchronization of neural network activity. The eEF2K-inhibition mediated potentiation of synaptic transmission of hippocampal CA1 neurons is most notably independent of protein synthesis and does not rely on protein kinase C, protein kinase A or mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase 1/2. Moreover, the strengthening of synaptic transmission in the response to the inhibition of eEF2K was strongly attenuated by the inhibition of p38 MAPK. In addition, we show the involvement of barium-sensitive and more specific the TWIK-related potassium-1 (TREK-1) channels in the eEF2K-inhibition mediated potentiation of synaptic transmission. These findings reveal a novel pathway of eEF2K mediated regulation of hippocampal synaptic transmission. Further research is required to study whether such compounds could be beneficial for the development of mood disorder treatments with a fast-acting antidepressant response.

Spectral singularities of complex scattering potentials and infinite reflection and transmission coefficients at real energies.

PubMed

Mostafazadeh, Ali

2009-06-05

Spectral singularities are spectral points that spoil the completeness of the eigenfunctions of certain non-Hermitian Hamiltonian operators. We identify spectral singularities of complex scattering potentials with the real energies at which the reflection and transmission coefficients tend to infinity, i.e., they correspond to resonances having a zero width. We show that a waveguide modeled using such a potential operates like a resonator at the frequencies of spectral singularities. As a concrete example, we explore the spectral singularities of an imaginary PT-symmetric barrier potential and demonstrate the above resonance phenomenon for a certain electromagnetic waveguide.

Spectral Singularities of Complex Scattering Potentials and Infinite Reflection and Transmission Coefficients at Real Energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mostafazadeh, Ali

2009-06-05

Spectral singularities are spectral points that spoil the completeness of the eigenfunctions of certain non-Hermitian Hamiltonian operators. We identify spectral singularities of complex scattering potentials with the real energies at which the reflection and transmission coefficients tend to infinity, i.e., they correspond to resonances having a zero width. We show that a waveguide modeled using such a potential operates like a resonator at the frequencies of spectral singularities. As a concrete example, we explore the spectral singularities of an imaginary PT-symmetric barrier potential and demonstrate the above resonance phenomenon for a certain electromagnetic waveguide.

Potentiation of NMDA receptor-mediated transmission in striatal cholinergic interneurons

PubMed Central

Oswald, Manfred J.; Schulz, Jan M.; Kelsch, Wolfgang; Oorschot, Dorothy E.; Reynolds, John N. J.

2015-01-01

Pauses in the tonic firing of striatal cholinergic interneurons (CINs) emerge during reward-related learning in response to conditioning of a neutral cue. We have previously reported that augmenting the postsynaptic response to cortical afferents in CINs is coupled to the emergence of a cell-intrinsic afterhyperpolarization (AHP) underlying pauses in tonic activity. Here we investigated in a bihemispheric rat-brain slice preparation the mechanisms of synaptic plasticity of excitatory afferents to CINs and the association with changes in the AHP. We found that high frequency stimulation (HFS) of commissural corticostriatal afferents from the contralateral hemisphere induced a robust long-term depression (LTD) of postsynaptic potentials (PSP) in CINs. Depression of the PSP of smaller magnitude and duration was observed in response to HFS of the ipsilateral white matter or cerebral cortex. In Mg2+-free solution HFS induced NMDA receptor-dependent potentiation of the PSP, evident in both the maximal slope and amplitude of the PSP. The increase in maximal slope corroborates previous findings, and was blocked by antagonism of either D1-like dopamine receptors with SCH23390 or D2-like dopamine receptors with sulpiride during HFS in Mg2+-free solution. Potentiation of the slower PSP amplitude component was due to augmentation of the NMDA receptor-mediated potential as this was completely reversed on subsequent application of the NMDA receptor antagonist AP5. HFS similarly potentiated NMDA receptor currents isolated by blockade of AMPA/kainate receptors with CNQX. The plasticity-induced increase in the slow PSP component was directly associated with an increase in the subsequent AHP. Thus plasticity of cortical afferent synapses is ideally suited to influence the cue-induced firing dynamics of CINs, particularly through potentiation of NMDA receptor-mediated synaptic transmission. PMID:25914618

Potentiation of NMDA receptor-mediated transmission in striatal cholinergic interneurons.

PubMed

Oswald, Manfred J; Schulz, Jan M; Kelsch, Wolfgang; Oorschot, Dorothy E; Reynolds, John N J

2015-01-01

Pauses in the tonic firing of striatal cholinergic interneurons (CINs) emerge during reward-related learning in response to conditioning of a neutral cue. We have previously reported that augmenting the postsynaptic response to cortical afferents in CINs is coupled to the emergence of a cell-intrinsic afterhyperpolarization (AHP) underlying pauses in tonic activity. Here we investigated in a bihemispheric rat-brain slice preparation the mechanisms of synaptic plasticity of excitatory afferents to CINs and the association with changes in the AHP. We found that high frequency stimulation (HFS) of commissural corticostriatal afferents from the contralateral hemisphere induced a robust long-term depression (LTD) of postsynaptic potentials (PSP) in CINs. Depression of the PSP of smaller magnitude and duration was observed in response to HFS of the ipsilateral white matter or cerebral cortex. In Mg(2+)-free solution HFS induced NMDA receptor-dependent potentiation of the PSP, evident in both the maximal slope and amplitude of the PSP. The increase in maximal slope corroborates previous findings, and was blocked by antagonism of either D1-like dopamine receptors with SCH23390 or D2-like dopamine receptors with sulpiride during HFS in Mg(2+)-free solution. Potentiation of the slower PSP amplitude component was due to augmentation of the NMDA receptor-mediated potential as this was completely reversed on subsequent application of the NMDA receptor antagonist AP5. HFS similarly potentiated NMDA receptor currents isolated by blockade of AMPA/kainate receptors with CNQX. The plasticity-induced increase in the slow PSP component was directly associated with an increase in the subsequent AHP. Thus plasticity of cortical afferent synapses is ideally suited to influence the cue-induced firing dynamics of CINs, particularly through potentiation of NMDA receptor-mediated synaptic transmission.

The potential role of Wolbachia in controlling the transmission of emerging human arboviral infections

PubMed Central

Kamtchum-Tatuene, Joseph; Makepeace, Benjamin L.; Benjamin, Laura; Baylis, Matthew; Solomon, Tom

2017-01-01

Purpose of review Wolbachia is a genus of Gram-negative intracellular bacteria that is naturally found in more than half of all arthropod species. These bacteria cannot only reduce the fitness and the reproductive capacities of arthropod vectors, but also increase their resistance to arthropod-borne viruses (arboviruses). This article reviews the evidence supporting a Wolbachia-based strategy for controlling the transmission of dengue and other arboviral infections. Recent findings Studies conducted 1 year after the field release of Wolbachia-infected mosquitoes in Australia have demonstrated the suppression of dengue virus (DENV) replication in and dissemination by mosquitoes. Recent mathematical models show that this strategy could reduce the transmission of DENV by 70%. Consequently, the WHO is encouraging countries to boost the development and implementation of Wolbachia-based prevention strategies against other arboviral infections. However, the evidence regarding the efficacy of Wolbachia to prevent the transmission of other arboviral infections is still limited to an experimental framework with conflicting results in some cases. There is a need to demonstrate the efficacy of such strategies in the field under various climatic conditions, to select the Wolbachia strain that has the best pathogen interference/spread trade-off, and to continue to build community acceptance. Summary Wolbachia represents a promising tool for controlling the transmission of arboviral infections that needs to be developed further. Long-term environmental monitoring will be necessary for timely detection of potential changes in Wolbachia/vector/virus interactions. PMID:27849636

Durable Viral Suppression and Transmission Risk Potential Among Persons With Diagnosed HIV Infection: United States, 2012-2013.

PubMed

Crepaz, Nicole; Tang, Tian; Marks, Gary; Mugavero, Michael J; Espinoza, Lorena; Hall, H Irene

2016-10-01

We examined durable viral suppression, cumulative viral load (VL) burden, and transmission risk potential among human immunodeficiency virus (HIV)-diagnosed persons in care. Using data from the National HIV Surveillance System from 17 jurisdictions with complete reporting of VL test results, we determined the percentage of persons in HIV care who achieved durable viral suppression (all VL results <200 copies/mL) and examined viremia copy-years and time spent above VL levels that increase the risk of HIV transmission during 2012-2013. Of 265 264 persons in HIV care in 2011, 238 641 had at least 2 VLs in 2012-2013. The median number of VLs per individual during the 2-year period was 5. Approximately 62% had durable viral suppression. The remaining 38% had high VL burden (geometric mean of viremia copy-years, 7261) and spent an average of 438 days, 316 days, and 215 days (60%, 43.2%, and 29.5% of the 2-year period) above 200, 1500, and 10 000 copies/mL. Women, blacks/African Americans, Hispanics/Latinos, persons with HIV infection attributed to transmission other than male-to-male sexual contact, younger age groups, and persons with gaps in care had higher viral burden and transmission risk potential. Two-thirds of persons in HIV care had durable viral suppression during a 2-year period. One-third had high VL burden and spent substantial time above VL levels with increased risk of onward transmission. More intervention efforts are needed to improve retention in care and medication adherence so that more persons in HIV care achieve durable viral suppression. Published by Oxford University Press for the Infectious Diseases Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Short report: secondary transmission in porcine cysticercosis: description and their potential implications for control sustainability.

PubMed

Gonzalez, Armando E; López-Urbina, Teresa; Tsang, Byron Y; Gavidia, César M; Garcia, Héctor H; Silva, María E; Ramos, Daphne D; Manzanedo, Rafael; Sánchez-Hidalgo, Lelia; Gilman, Robert H; Tsang, Victor C W

2005-09-01

Taenia solium taeniasis/cysticercosis is one of few potentially eradicable infectious diseases and is the target of control programs in several countries. The larval stage of this zoonotic cestode invades the human brain and is responsible for most cases of adult-onset epilepsy in the world. The pig is the natural intermediate host, harboring the larvae or cysticerci. Our current understanding of the life cycle implicates humans as the only definitive host and tapeworm carrier (developing taeniasis) and thus the sole source of infective eggs that are responsible for cysticercosis in both human and pigs through oral-fecal transmission. Here we show evidence of an alternative pig-to-pig route of transmission, previously not suspected to exist. In a series of four experiments, naive sentinel pigs were exposed to pigs that had been infected orally with tapeworm segments (containing infective eggs) and moved to a clean environment. Consistently in all four experiments, at least one of the sentinel pigs became seropositive or infected with parasite cysts with much lower cyst burdens than did primarily infected animals. Second-hand transmission of Taenia solium eggs could explain the overdispersed pattern of porcine cysticercosis, with few pigs harboring heavy parasite burdens and many more harboring small numbers of parasites. This route of transmission opens new avenues for consideration with respect to control strategies.

Surface self-potential patterns related to transmissive fracture trends during a water injection test

NASA Astrophysics Data System (ADS)

DesRoches, A. J.; Butler, K. E.; MacQuarrie, K. TB

2018-03-01

Variations in self-potential (SP) signals were recorded over an electrode array during a constant head injection test in a fractured bedrock aquifer. Water was injected into a 2.2 m interval isolated between two inflatable packers at 44 m depth in a vertical well. Negative SP responses were recorded on surface corresponding to the start of the injection period with strongest magnitudes recorded in electrodes nearest the well. SP response decreased in magnitude at electrodes further from the well. Deflation of the packer system resulted in a strong reversal in the SP signal. Anomalous SP patterns observed at surface at steady state were found to be aligned with dominant fracture strike orientations found within the test interval. Numerical modelling of fluid and current flow within a simplified fracture network showed that azimuthal patterns in SP are mainly controlled by transmissive fracture orientations. The strongest SP gradients occur parallel to hydraulic gradients associated with water flowing out of the transmissive fractures into the tighter matrix and other less permeable cross-cutting fractures. Sensitivity studies indicate that increasing fracture frequency near the well increases the SP magnitude and enhances the SP anomaly parallel to the transmissive set. Decreasing the length of the transmissive fractures leads to more fluid flow into the matrix and into cross-cutting fractures proximal to the well, resulting in a more circular and higher magnitude SP anomaly. Results from the field experiment and modelling provide evidence that surface-based SP monitoring during constant head injection tests has the ability to identify groundwater flow pathways within a fractured bedrock aquifer.

Potential effects of mixed infections in ticks on transmission dynamics of pathogens: comparative analysis of published records

USGS Publications Warehouse

Ginsberg, Howard S.

2008-01-01

Ticks are often infected with more than one pathogen, and several field surveys have documented nonrandom levels of coinfection. Levels of coinfection by pathogens in four tick species were analyzed using published infection data. Coinfection patterns of pathogens in field-collected ticks include numerous cases of higher or lower levels of coinfection than would be expected due to chance alone, but the vast majority of these cases can be explained on the basis of vertebrate host associations of the pathogens, without invoking interactions between pathogens within ticks. Nevertheless, some studies have demonstrated antagonistic interactions, and some have suggested potential mutualisms, between pathogens in ticks. Negative or positive interactions between pathogens within ticks can affect pathogen prevalence, and thus transmission patterns. Probabilistic projections suggest that the effect on transmission depends on initial conditions. When the number of tick bites is relatively low (e.g., for ticks biting humans) changes in prevalence in ticks are predicted to have a commensurate effects on pathogen transmission. In contrast, when the number of tick bites is high (e.g., for wild animal hosts) changes in pathogen prevalence in ticks have relatively little effect on levels of transmission to reservoir hosts, and thus on natural transmission cycles.

Compressed television transmission: A market survey

NASA Technical Reports Server (NTRS)

Lizak, R. M.; Cagan, L. Q.

1981-01-01

NASA's compressed television transmission technology is described, and its potential market is considered; a market that encompasses teleconferencing, remote medical diagnosis, patient monitoring, transit station surveillance, as well as traffic management and control. In addition, current and potential television transmission systems and their costs and potential manufacturers are considered.

HIV Transmission

PubMed Central

Shaw, George M.; Hunter, Eric

2012-01-01

HIV-1 is transmitted by sexual contact across mucosal surfaces, by maternal-infant exposure, and by percutaneous inoculation. For reasons that are still incompletely understood, CCR5-tropic viruses (R5 viruses) are preferentially transmitted by all routes. Transmission is followed by an orderly appearance of viral and host markers of infection in the blood plasma. In the acute phase of infection, HIV-1 replicates exponentially and diversifies randomly, allowing for an unambiguous molecular identification of transmitted/founder virus genomes and a precise characterization of the population bottleneck to virus transmission. Sexual transmission of HIV-1 most often results in productive clinical infection arising from a single virus, highlighting the extreme bottleneck and inherent inefficiency in virus transmission. It remains to be determined if HIV-1 transmission is largely a stochastic process whereby any reasonably fit R5 virus can be transmitted or if there are features of transmitted/founder viruses that facilitate their transmission in a biologically meaningful way. Human tissue explant models of HIV-1 infection and animal models of SIV/SHIV/HIV-1 transmission, coupled with new challenge virus strains that more closely reflect transmitted/founder viruses, have the potential to elucidate fundamental mechanisms in HIV-1 transmission relevant to vaccine design and other prevention strategies. PMID:23043157

Event-related brain potentials and cognitive processes related to perceptual-motor information transmission.

PubMed

Kopp, Bruno; Wessel, Karl

2010-05-01

In the present study, event-related potentials (ERPs) were recorded to investigate cognitive processes related to the partial transmission of information from stimulus recognition to response preparation. Participants classified two-dimensional visual stimuli with dimensions size and form. One feature combination was designated as the go-target, whereas the other three feature combinations served as no-go distractors. Size discriminability was manipulated across three experimental conditions. N2c and P3a amplitudes were enhanced in response to those distractors that shared the feature from the faster dimension with the target. Moreover, N2c and P3a amplitudes showed a crossover effect: Size distractors evoked more pronounced ERPs under high size discriminability, but form distractors elicited enhanced ERPs under low size discriminability. These results suggest that partial perceptual-motor transmission of information is accompanied by acts of cognitive control and by shifts of attention between the sources of conflicting information. Selection negativity findings imply adaptive allocation of visual feature-based attention across the two stimulus dimensions.

Leishmaniasis transmission in an ecotourism area: potential vectors in Ilha Grande, Rio de Janeiro State, Brazil

PubMed Central

2013-01-01

Background The south coast of Rio de Janeiro State, in Brazil, is endemic for cutaneous and visceral leishmaniases and is frequently visited by tourists from different parts of the world. Since the complex epidemiology of leishmaniases demands local studies, the goal of this study was to investigate the phlebotomine sand fly fauna and leishmaniases transmission in Ilha Grande, an ecotourism area of Angra dos Reis municipality. Methods Sand fly fauna was sampled in three monitoring stations using HP light traps in domiciles, peridomiciles and forests. Species abundance was evaluated by the Index of Species Abundance. A Leishmania natural infection survey was done using multiplex PCR and dot blot hybridization. Results During 15 consecutive months of sand fly monitoring, 1093 specimens from 16 species were captured. The potential leishmaniases vectors found were Lutzomyia (Nyssomyia) intermedia, L. migonei, L. (N.) flaviscutellata, L. (Psychodopygus) ayrozai and L. (Lutzomyia) longipalpis. Five species were new records in Ilha Grande: L. (Sciopemyia) microps, L. termitophila, L. firmatoi, L. rupicola and L. (P.) ayrozai. Higher species richness was found inside forest areas, although potential leishmaniases vectors were present in deforested areas, peridomiciles and inside houses. Lutzomyia (N.) intermedia and L. migonei were the most abundant species. Females of L. migonei showed a high rate (10.3%) of natural infection by Leishmania (Viannia) sp., probably Leishmania (V.) braziliensis. Conclusions The detection of leishmaniases transmission and potential vectors in Ilha Grande is of public health concern, especially because tourists are frequently visiting the island. Besides reinforcing the epidemiological importance of L. (N.) intermedia in Rio de Janeiro State, the role of L. migonei in cutaneous leishmaniasis transmission is highlighted with its high rate of Leishmania natural infection. The finding of L. (L.) longipalpis confirmed the human autochthonous case

Leishmaniasis transmission in an ecotourism area: potential vectors in Ilha Grande, Rio de Janeiro State, Brazil.

PubMed

Carvalho, Bruno Moreira; Maximo, Michele; Costa, Wagner Alexandre; de Santana, Antonio Luís Ferreira; da Costa, Simone Miranda; da Costa Rego, Taiana Amancio Neves; de Pita Pereira, Daniela; Rangel, Elizabeth Ferreira

2013-11-13

The south coast of Rio de Janeiro State, in Brazil, is endemic for cutaneous and visceral leishmaniases and is frequently visited by tourists from different parts of the world. Since the complex epidemiology of leishmaniases demands local studies, the goal of this study was to investigate the phlebotomine sand fly fauna and leishmaniases transmission in Ilha Grande, an ecotourism area of Angra dos Reis municipality. Sand fly fauna was sampled in three monitoring stations using HP light traps in domiciles, peridomiciles and forests. Species abundance was evaluated by the Index of Species Abundance. A Leishmania natural infection survey was done using multiplex PCR and dot blot hybridization. During 15 consecutive months of sand fly monitoring, 1093 specimens from 16 species were captured. The potential leishmaniases vectors found were Lutzomyia (Nyssomyia) intermedia, L. migonei, L. (N.) flaviscutellata, L. (Psychodopygus) ayrozai and L. (Lutzomyia) longipalpis. Five species were new records in Ilha Grande: L. (Sciopemyia) microps, L. termitophila, L. firmatoi, L. rupicola and L. (P.) ayrozai. Higher species richness was found inside forest areas, although potential leishmaniases vectors were present in deforested areas, peridomiciles and inside houses. Lutzomyia (N.) intermedia and L. migonei were the most abundant species. Females of L. migonei showed a high rate (10.3%) of natural infection by Leishmania (Viannia) sp., probably Leishmania (V.) braziliensis. The detection of leishmaniases transmission and potential vectors in Ilha Grande is of public health concern, especially because tourists are frequently visiting the island. Besides reinforcing the epidemiological importance of L. (N.) intermedia in Rio de Janeiro State, the role of L. migonei in cutaneous leishmaniasis transmission is highlighted with its high rate of Leishmania natural infection. The finding of L. (L.) longipalpis confirmed the human autochthonous case of visceral leishmaniasis from the

[Ecology of Anopheles (Nyssorhynchus) darlingi Root in the installation area of a hydroelectric scheme on the border between the States of Mato Grosso do Sul and São Paulo].

PubMed

Gomes, Almério de Castro; Paula, Marcia Bicudo de; Natal, Delsio; Gotlieb, Sabina Lea Davidson

2010-01-01

Hydroelectric schemes modify the water flow and cause an impact on mosquito composition, thus justifying investigations. The aim of this study was to study anophelines in the area under the influence of a new lake and to evaluate their relative vulnerability to malaria. Anopheles specimens were collected from the edges of the Porto Primavera reservoir, during the phases of reservoir filling until its maximum level was reached. The techniques used were attraction to humans, Shannon traps and entomological scoops. The richness and diversity indexes were used to measure the impact. The temporal distribution analysis was performed using the Mann-Whitney test, taking the site, level and capture method as independent variables (alpha = 0.05). The density of Anopheles darlingi oscillated among the sites A, B and C, and the biggest peaks were located at B and C. After the lake reached its stable maximum level, there was a tendency for the density to decrease. It is suggested that the risk of autochthonous malaria in the vicinity of the lake remained unchanged, but it is necessary to remain alert regarding sporadic human infections.

An Analysis of the Potential Impact of Climate Change on Dengue Transmission in the Southeastern United States

PubMed Central

Butterworth, Melinda K.; Morin, Cory W.; Comrie, Andrew C.

2016-01-01

MK, Morin CW, Comrie AC. 2017. An analysis of the potential impact of climate change on dengue transmission in the southeastern United States. Environ Health Perspect 125:579–585; http://dx.doi.org/10.1289/EHP218 PMID:27713106

Bobcats (Lynx rufus) are natural definitive host of Besnoitia darlingi

USDA-ARS?s Scientific Manuscript database

Bovine besnoitiosis, caused by Besnoitia besnoiti, is an economically important disease of cattle in many countries but its transmission remains a mystery. Wild felids are suspected to be its definitive hosts. The domestic cat (Felis catus) is known experimental definitive host for Besnoitia species...

Self-similar transmission properties of aperiodic Cantor potentials in gapped graphene

NASA Astrophysics Data System (ADS)

Rodríguez-González, Rogelio; Rodríguez-Vargas, Isaac; Díaz-Guerrero, Dan Sidney; Gaggero-Sager, Luis Manuel

2016-01-01

We investigate the transmission properties of quasiperiodic or aperiodic structures based on graphene arranged according to the Cantor sequence. In particular, we have found self-similar behaviour in the transmission spectra, and most importantly, we have calculated the scalability of the spectra. To do this, we implement and propose scaling rules for each one of the fundamental parameters: generation number, height of the barriers and length of the system. With this in mind we have been able to reproduce the reference transmission spectrum, applying the appropriate scaling rule, by means of the scaled transmission spectrum. These scaling rules are valid for both normal and oblique incidence, and as far as we can see the basic ingredients to obtain self-similar characteristics are: relativistic Dirac electrons, a self-similar structure and the non-conservation of the pseudo-spin.

Hepatitis B virus lineages in mammalian hosts: Potential for bidirectional cross-species transmission

PubMed Central

Bonvicino, Cibele R; Moreira, Miguel A; Soares, Marcelo A

2014-01-01

The hepatitis B virus (HBV) is a cosmopolitan infectious agent currently affecting over 350 million people worldwide, presently accounting for more than two billion infections. In addition to man, other hepatitis virus strains infect species of several mammalian families of the Primates, Rodentia and Chiroptera orders, in addition to birds. The mounting evidence of HBV infection in African, Asian and neotropical primates draws attention to the potential cross-species, zoonotic transmission of these viruses to man. Moreover, recent evidence also suggests the humans may also function as a source of viral infection to other mammals, particularly to domestic animals like poultry and swine. In this review, we list all evidence of HBV and HBV-like infection of nonhuman mammals and discuss their potential roles as donors or recipients of these viruses to humans and to other closely-related species. PMID:24976704

Potential for human immunodeficiency virus parenteral transmission in the Middle East and North Africa: An analysis using hepatitis C virus as a proxy biomarker

PubMed Central

Mohamoud, Yousra A; Miller, F DeWolfe; Abu-Raddad, Laith J

2014-01-01

The Middle East and North Africa (MENA) region has endured several major events of infection parenteral transmission. Recent work has established the utility of using hepatitis C virus (HCV) as a proxy biomarker for assessing the epidemic potential for human immunodeficiency virus (HIV) parenteral transmission. In this review, we use data on the prevalence of HCV infection antibody (seroprevalence) among general population and high risk population groups to assess the potential for HIV parenteral transmission in MENA. Relatively low prevalence of HCV infection in the general population groups was reported in most MENA countries indicating that parenteral HIV transmission at endemic levels does not appear to be a cause for concern. Nonetheless, there could be opportunities for localized HIV outbreaks and transmission of other blood-borne infections in some settings such as healthcare facilities. Though there have been steady improvements in safety measures related to parenteral modes of transmission in the region, these improvements have not been uniform across all countries. More precautions, including infection control training programs, surveillance systems for nosocomial infections and wider coverage and evaluation of hepatitis B virus immunization programs need to be implemented to avoid the unnecessary spread of HIV, HCV, and other blood-borne pathogens along the parenteral modes of transmission. PMID:25278675

CGRP potentiates excitatory transmission to the circular muscle of guinea-pig colon.

PubMed

Maggi, C A; Giuliani, S; Santicioli, P

1997-04-30

potential (i.j.p.) and a small excitatory junction potential (e.j.p.). CGRP (0.1 microM) produced membrane hyperpolarization and relaxation without affecting i.j.p. amplitude but concomitantly increased the e.j.p. amplitude to induce a contraction in correspondence to each electrical pulse. In the presence of the NK1 receptor antagonist, GR 82334 (3 microM), the membrane hyperpolarization and relaxation produced by CGRP and the EFS-evoked i.j.p. were unaffected, while the potentiating effect of CGRP on the EFS-evoked NANC e.j.p. and the corresponding contraction were abolished. We conclude that, in addition to the previously characterized direct smooth muscle relaxant action via CGRP1 receptors (Maggi et al. Regulatory Peptides 61, 27-36, 1996), CGRP also induces a remarkable potentiation of excitatory neurotransmission to the circular muscle of the guinea-pig colon via CGRP2 receptors. The latter effect, documented in this study, is evidenced on both the atropine-sensitive and the atropine-resistant (tachykinin-mediated) components of excitatory transmission: this effect does not involve mediator(s) release from capsaicin-sensitive primary afferent nerves, nor inhibition of peptide degradation or modulation of NANC inhibitory transmission.

Hydrological modelling of snail dispersal patterns in Msambweni, Kenya and potential resurgence of Schistosoma haematobium transmission.

PubMed

Clennon, J A; King, C H; Muchiri, E M; Kitron, U

2007-05-01

Urinary schistosomiasis is an important source of human morbidity in Msambweni, Kenya, where the intermediate host snail, Bulinus nasutus is found in ponds and water pools. In the past, aquatic habitats in the area have been studied separately; however, recent collections of B. nasutus snails and shells indicated that many of these ponds are in fact connected during and following sufficient rains. Satellite imagery and a geographical information system (GIS) were used to survey the main water courses and potential drainage routes, to locate potential source populations of snails and to determine probable snail dispersal routes. The 2 water bodies implicated as being the most important Schistosoma haematobium transmission foci in the area were found to differ in their degree of connectivity to other B. nasutus source habitats. One pond becomes connected even after normal rains, while the other pond requires prolonged rains or flooding to become connected with source habitats. Consequently, the transmission foci differ in their susceptibility to snail population control measures. Spatially explicit dispersal models that consider the spatial and temporal patterns of connectivity between aquatic habitats will contribute to improved snail surveillance and more focused control for urinary schistosomiasis at a local level.

Dogma disputed: potential endemic heterosexual transmission of human immunodeficiency virus in Australia.

PubMed

Chapman, S

1992-06-01

The concept of tertiary sexual transmission of human immunodeficiency virus (HIV) has been central to government efforts to communicate notions of risk to heterosexuals in Australia. Data on heterosexually transmitted acquired immune deficiency syndrome (AIDS) and HIV for Australia are reviewed with emphasis given to the probability of misclassification bias in the heterosexually acquired and 'other/undetermined' categories. Tertiary cases are almost certainly rare in Australia, with little evidence of any increase in their incidence since the first cases were recorded. Three factors (low probability of exposure, the infectivity of HIV and a comparatively low rate of sexual partner change) make it improbable that Australian heterosexuals with no risk factors will experience endemic HIV infection, with a caveat to this conclusion lying in the potential of Australian sex tourism to Southeast Asia for introducing HIV into the Australian heterosexual population. Four hegemonic factors which have acted to suppress any serious debate of the notion that HIV in Australia is unlikely to become endemic among heterosexuals are discussed: the political 'democratization' of risk inspired by concerns that gay men should not be further vilified as a victim group; the preventive imperative; a reluctance among health educators to question the very foundations of the message they are employed to deliver; and a reluctance to curtail 'Trojan horse' benefits to sexually transmissible disease prevention engendered by HIV education promoting safe sex messages.

Blunted Dopamine Transmission in Addiction: Potential Mechanisms and Implications for Behavior.

PubMed

Trifilieff, Pierre; Ducrocq, Fabien; van der Veldt, Suzanne; Martinez, Diana

2017-01-01

Positron emission tomography (PET) imaging consistently shows blunted striatal dopamine release and decreased dopamine D2 receptor availability in addiction. Here, we review the preclinical and clinical studies indicating that this neurobiological phenotype is likely to be both a consequence of chronic drug consumption and a vulnerability factor in the development of addiction. We propose that, behaviorally, blunted striatal dopamine transmission could reflect the increased impulsivity and altered cost/benefit computations that are associated with addiction. The factors that influence blunted striatal dopamine transmission in addiction are unknown. Herein, we give an overview of various factors, genetic, environmental, and social, that are known to affect dopamine transmission and that have been associated with the vulnerability to develop addiction. Altogether, these data suggest that blunted dopamine transmission and decreased D2 receptor availability are biomarkers both for the development of addiction and resistance to treatment. These findings support the view that blunted dopamine reflects impulsive behavior and deficits in motivation, which lead to the escalation of drug use. Copyright © 2017 Elsevier Inc. All rights reserved.

Light transmission through intraocular lenses with or without yellow chromophore (blue light filter) and its potential influence on functional vision in everyday environmental conditions.

PubMed

Owczarek, Grzegorz; Gralewicz, Grzegorz; Skuza, Natalia; Jurowski, Piotr

2016-01-01

In this research the factors used to evaluate the light transmission through two types of acrylic hydrophobic intraocular lenses, one that contained yellow chromophore that blocks blue light transmission and the other which did not contain that filter, were defined according to various light condition, e.g., daylight and at night. The potential influence of light transmission trough intraocular lenses with or without yellow chromophore on functional vision in everyday environmental conditions was analysed.

Electricity Transmission, Pipelines, and National Trails. An Analysis of Current and Potential Intersections on Federal Lands in the Eastern United States, Alaska, and Hawaii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuiper, James A; Krummel, John R; Hlava, Kevin J

2014-03-25

As has been noted in many reports and publications, acquiring new or expanded rights-of-way for transmission is a challenging process, because numerous land use and land ownership constraints must be overcome to develop pathways suitable for energy transmission infrastructure. In the eastern U.S., more than twenty federally protected national trails (some of which are thousands of miles long, and cross many states) pose a potential obstacle to the development of new or expanded electricity transmission capacity. However, the scope of this potential problem is not well-documented, and there is no baseline information available that could allow all stakeholders to studymore » routing scenarios that could mitigate impacts on national trails. This report, Electricity Transmission, Pipelines, and National Trails: An Analysis of Current and Potential Intersections on Federal Lands in the Eastern United States, was prepared by the Environmental Science Division of Argonne National Laboratory (Argonne). Argonne was tasked by DOE to analyze the “footprint” of the current network of National Historic and Scenic Trails and the electricity transmission system in the 37 eastern contiguous states, Alaska, and Hawaii; assess the extent to which national trails are affected by electrical transmission; and investigate the extent to which national trails and other sensitive land use types may be affected in the near future by planned transmission lines. Pipelines are secondary to transmission lines for analysis, but are also within the analysis scope in connection with the overall directives of Section 368 of the Energy Policy Act of 2005, and because of the potential for electrical transmission lines being collocated with pipelines. Based on Platts electrical transmission line data, a total of 101 existing intersections with national trails on federal land were found, and 20 proposed intersections. Transmission lines and pipelines are proposed in Alaska; however there are no

µ-Conotoxins Modulating Sodium Currents in Pain Perception and Transmission: A Therapeutic Potential

PubMed Central

Tosti, Elisabetta; Boni, Raffaele

2017-01-01

The Conus genus includes around 500 species of marine mollusks with a peculiar production of venomous peptides known as conotoxins (CTX). Each species is able to produce up to 200 different biological active peptides. Common structure of CTX is the low number of amino acids stabilized by disulfide bridges and post-translational modifications that give rise to different isoforms. µ and µO-CTX are two isoforms that specifically target voltage-gated sodium channels. These, by inducing the entrance of sodium ions in the cell, modulate the neuronal excitability by depolarizing plasma membrane and propagating the action potential. Hyperexcitability and mutations of sodium channels are responsible for perception and transmission of inflammatory and neuropathic pain states. In this review, we describe the current knowledge of µ-CTX interacting with the different sodium channels subtypes, the mechanism of action and their potential therapeutic use as analgesic compounds in the clinical management of pain conditions. PMID:28937587

Investigation of hydraulic transmission noise sources

NASA Astrophysics Data System (ADS)

Klop, Richard J.

Advanced hydrostatic transmissions and hydraulic hybrids show potential in new market segments such as commercial vehicles and passenger cars. Such new applications regard low noise generation as a high priority, thus, demanding new quiet hydrostatic transmission designs. In this thesis, the aim is to investigate noise sources of hydrostatic transmissions to discover strategies for designing compact and quiet solutions. A model has been developed to capture the interaction of a pump and motor working in a hydrostatic transmission and to predict overall noise sources. This model allows a designer to compare noise sources for various configurations and to design compact and inherently quiet solutions. The model describes dynamics of the system by coupling lumped parameter pump and motor models with a one-dimensional unsteady compressible transmission line model. The model has been verified with dynamic pressure measurements in the line over a wide operating range for several system structures. Simulation studies were performed illustrating sensitivities of several design variables and the potential of the model to design transmissions with minimal noise sources. A semi-anechoic chamber has been designed and constructed suitable for sound intensity measurements that can be used to derive sound power. Measurements proved the potential to reduce audible noise by predicting and reducing both noise sources. Sound power measurements were conducted on a series hybrid transmission test bench to validate the model and compare predicted noise sources with sound power.

A survey of endangered waterbirds on Maui and Oahu and assessment of potential impacts to waterbirds from the proposed Hawaii Geothermal Project transmission corridor. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, K.; Woodside, D.; Bruegmann, M.

1994-08-01

A survey of endangered waterbirds on Maui and Oahu was conducted during August and September 1993 to identify potential waterbird habitats within the general area of the proposed Hawaii Geothermal Project transmission corridor and to assess the potential impacts to endangered waterbird of installing and operating a high voltage transmission line from the Island of Hawaii to the islands of Oahu and Maui. Annual waterbird survey information and other literature containing information on specific wetland sites were summarized. Literature describing impacts of overhead transmission lines on birds was used to evaluate potential impacts of the proposed project on endangered waterbirds,more » resident wading birds, and migratory shorebirds and waterfowl. On Oahu, five wetland habitats supporting endangered Hawaiian waterbirds were identified within 2.5 miles of the proposed transmission line corridor. On Maui, three wetland habitats supporting endangered Hawaiian waterbirds were identified within the general area of the proposed transmission line corridor. Several of the wetlands identified on Oahu and Maui also supported resident wading birds and migratory shorebirds and waterfowl. Endangered waterbirds, resident wading birds, and migratory birds may collide with the proposed transmission lines wires. The frequency and numbers of bird collisions is expected to be greater on Oahu than on Maui because more wetland habitat exists and greater numbers of birds occur in the project area on Oahu. In addition, the endangered Hawaiian goose and the endangered Hawaiian petrel may be impacted by the proposed segment of the Hawaii Geothermal Project transmission line on Maui.« less

Ape malaria transmission and potential for ape-to-human transfers in Africa

PubMed Central

Makanga, Boris; Yangari, Patrick; Rahola, Nil; Rougeron, Virginie; Elguero, Eric; Boundenga, Larson; Moukodoum, Nancy Diamella; Okouga, Alain Prince; Arnathau, Céline; Durand, Patrick; Willaume, Eric; Ayala, Diego; Fontenille, Didier; Ayala, Francisco J.; Renaud, François; Ollomo, Benjamin; Prugnolle, Franck; Paupy, Christophe

2016-01-01

Recent studies have highlighted the large diversity of malaria parasites infecting African great apes (subgenus Laverania) and their strong host specificity. Although the existence of genetic incompatibilities preventing the cross-species transfer may explain host specificity, the existence of vectors with a high preference for a determined host represents another possibility. To test this hypothesis, we undertook a 15-mo-long longitudinal entomological survey in two forest regions of Gabon, where wild apes live, at different heights under the canopy. More than 2,400 anopheline mosquitoes belonging to 18 species were collected. Among them, only three species of Anopheles were found infected with ape Plasmodium: Anopheles vinckei, Anopheles moucheti, and Anopheles marshallii. Their role in transmission was confirmed by the detection of the parasites in their salivary glands. Among these species, An. vinckei showed significantly the highest prevalence of infection and was shown to be able to transmit parasites of both chimpanzees and gorillas. Transmission was also shown to be conditioned by seasonal factors and by the heights of capture under the canopy. Moreover, human landing catches of sylvan Anopheles demonstrated the propensity of these three vector species to feed on humans when available. Our results suggest therefore that the strong host specificity observed in the Laveranias is not linked to a specific association between the vertebrate host and the vector species and highlight the potential role of these vectors as bridge between apes and humans. PMID:27071123

Spatial and temporal variation in biting rates and parasite transmission potentials of onchocerciasis vectors in Ecuador.

PubMed

Vieira, J C; Brackenboro, L; Porter, C H; Basáñez, M-G; Collins, R C

2005-03-01

The influence of spatial and temporal factors on onchocerciasis transmission by Simulium exiguum s.l. and S. quadrivittatum in Ecuador was investigated to help develop sampling protocols for entomological surveillance of ivermectin programmes. Flies were collected in alternate months (November 1995-November 1996) at four sites each in the hyperendemic communities of San Miguel and El Tigre. A fixed-effects analysis of variance was used to explore the influence on vector abundance of locality, site, month and hour. Infectivity rates detected by dissection and PCR assays were compared. Simulium exiguum s.l. predominated at El Tigre (75%) whereas S. quadrivittatum prevailed at San Miguel (62%). Vector abundance was highest on river banks and outside houses. Biting and infection rates peaked from March to July. Hourly activity patterns were bimodal in S. exiguum but unimodal in S. quadrivittatum. Annual transmission potentials (ATP) for both species combined were 385 and 733 third stage larvae/person in San Miguel and El Tigre respectively, with S. exiguum accounting for 80% of the combined ATP at both localities. We recommend protocols that may maximize detection of parasite transmission. Infection rates thus obtained must be linked with vector density estimates to assess meaningfully host exposure as treatment progresses.

Epidemic Potential for Local Transmission of Zika Virus in 2015 and 2016 in Queensland, Australia.

PubMed

Viennet, Elvina; Mincham, Gina; Frentiu, Francesca D; Jansen, Cassie C; Montgomery, Brian L; Harley, David; Flower, Robert L P; Williams, Craig R; Faddy, Helen M

2016-12-13

Zika virus could be transmitted in the state of Queensland, Australia, in parts of the state where the mosquito vectors are established. We assessed the epidemic potential of Zika in Queensland from January 2015 to August 2016, and estimate the epidemic potential from September to December 2016, by calculating the temperature-dependent relative vectorial capacity (rVc), based on empirical and estimated parameters. Through 2015, we estimated a rVc of 0.119, 0.152, 0.170, and 0.175, respectively in the major cities of Brisbane, Rockhampton, Cairns, and Townsville. From January to August 2016, the epidemic potential trend was similar to 2015, however the highest epidemic potential was in Cairns. During September to November 2016, the epidemic potential is consistently the highest in Cairns, followed by Townsville, Rockhampton and Brisbane. Then, from November to December 2016, Townsville has the highest estimated epidemic potential. We demonstrate using a vectorial capacity model that ZIKV could have been locally transmitted in Queensland, Australia during 2015 and 2016. ZIKV remains a threat to Australia for the upcoming summer, during the Brazilian Carnival season, when the abundance of vectors is relatively high. Understanding the epidemic potential of local ZIKV transmission will allow better management of threats to blood safety and assessment of public health risk.

Potential for Zika virus introduction and transmission in resource limited countries in Africa and Asia-Pacific: A modeling study

PubMed Central

German, Matthew; Creatore, Maria I.; Brent, Shannon; Watts, Alexander G.; Hay, Simon I.; Kulkarni, Manisha A.; Brownstein, John S.; Khan, Kamran

2016-01-01

Summary Background As the epidemic of Zika virus expands in the Americas, countries across Africa and the Asia-Pacific region are becoming increasingly susceptible to the importation and possible local spread of the virus. To support public health readiness, we aim to identify regions and times where the potential health, economic, and social effects from Zika virus are greatest, focusing on resource-limited countries in Africa and the Asia-Pacific region. Methods Our model combined transportation network analysis, ecological modelling of mosquito occurrences, and vector competence for flavivirus transmission, using data from the International Air Transport Association, entomological observations from Zika’s primary vector species, and climate conditions using WorldClim. We overlaid monthly flows of airline travellers arriving to Africa and the Asia-Pacific region from areas of the Americas suitable for year-round transmission of Zika virus with monthly maps of climatic suitability for mosquito-borne transmission of Zika virus within Africa and the Asia-Pacific region. Findings An estimated 2·6 billion people live in areas of Africa and the Asia-Pacific region where the presence of competent mosquito vectors and suitable climatic conditions could support local transmission of Zika virus. Countries with large volumes of travellers arriving from Zika affected areas of the Americas and large populations at risk of mosquito-borne Zika virus infection include, India (67 422 travellers arriving per year; 1·2 billion residents in potential Zika transmission areas), China (238 415 travellers; 242 million residents), Indonesia (13 865 travellers; 197 million residents), Philippines (35 635 travellers; 70 million residents), and Thailand (29 241 travellers; 59 million residents). Interpretation Many countries across Africa and the Asia-Pacific region are vulnerable to Zika virus. Strategic use of available health and human resources is essential to prevent or mitigate

Global climate change and its potential impact on disease transmission by salinity-tolerant mosquito vectors in coastal zones.

PubMed

Ramasamy, Ranjan; Surendran, Sinnathamby Noble

2012-01-01

Global climate change can potentially increase the transmission of mosquito vector-borne diseases such as malaria, lymphatic filariasis, and dengue in many parts of the world. These predictions are based on the effects of changing temperature, rainfall, and humidity on mosquito breeding and survival, the more rapid development of ingested pathogens in mosquitoes and the more frequent blood feeds at moderately higher ambient temperatures. An expansion of saline and brackish water bodies (water with <0.5 ppt or parts per thousand, 0.5-30 ppt and >30 ppt salt are termed fresh, brackish, and saline respectively) will also take place as a result of global warming causing a rise in sea levels in coastal zones. Its possible impact on the transmission of mosquito-borne diseases has, however, not been adequately appreciated. The relevant impacts of global climate change on the transmission of mosquito-borne diseases in coastal zones are discussed with reference to the Ross-McDonald equation and modeling studies. Evidence is presented to show that an expansion of brackish water bodies in coastal zones can increase the densities of salinity-tolerant mosquitoes like Anopheles sundaicus and Culex sitiens, and lead to the adaptation of fresh water mosquito vectors like Anopheles culicifacies, Anopheles stephensi, Aedes aegypti, and Aedes albopictus to salinity. Rising sea levels may therefore act synergistically with global climate change to increase the transmission of mosquito-borne diseases in coastal zones. Greater attention therefore needs to be devoted to monitoring disease incidence and preimaginal development of vector mosquitoes in artificial and natural coastal brackish/saline habitats. It is important that national and international health agencies are aware of the increased risk of mosquito-borne diseases in coastal zones and develop preventive and mitigating strategies. Application of appropriate counter measures can greatly reduce the potential for increased

Global Climate Change and Its Potential Impact on Disease Transmission by Salinity-Tolerant Mosquito Vectors in Coastal Zones

PubMed Central

Ramasamy, Ranjan; Surendran, Sinnathamby Noble

2012-01-01

Global climate change can potentially increase the transmission of mosquito vector-borne diseases such as malaria, lymphatic filariasis, and dengue in many parts of the world. These predictions are based on the effects of changing temperature, rainfall, and humidity on mosquito breeding and survival, the more rapid development of ingested pathogens in mosquitoes and the more frequent blood feeds at moderately higher ambient temperatures. An expansion of saline and brackish water bodies (water with <0.5 ppt or parts per thousand, 0.5–30 ppt and >30 ppt salt are termed fresh, brackish, and saline respectively) will also take place as a result of global warming causing a rise in sea levels in coastal zones. Its possible impact on the transmission of mosquito-borne diseases has, however, not been adequately appreciated. The relevant impacts of global climate change on the transmission of mosquito-borne diseases in coastal zones are discussed with reference to the Ross–McDonald equation and modeling studies. Evidence is presented to show that an expansion of brackish water bodies in coastal zones can increase the densities of salinity-tolerant mosquitoes like Anopheles sundaicus and Culex sitiens, and lead to the adaptation of fresh water mosquito vectors like Anopheles culicifacies, Anopheles stephensi, Aedes aegypti, and Aedes albopictus to salinity. Rising sea levels may therefore act synergistically with global climate change to increase the transmission of mosquito-borne diseases in coastal zones. Greater attention therefore needs to be devoted to monitoring disease incidence and preimaginal development of vector mosquitoes in artificial and natural coastal brackish/saline habitats. It is important that national and international health agencies are aware of the increased risk of mosquito-borne diseases in coastal zones and develop preventive and mitigating strategies. Application of appropriate counter measures can greatly reduce the potential for

Dual Influence of Endocannabinoids on Long-Term Potentiation of Synaptic Transmission

PubMed Central

Silva-Cruz, Armando; Carlström, Mattias; Ribeiro, Joaquim A.; Sebastião, Ana M.

2017-01-01

Cannabinoid receptor 1 (CB1R) is widely distributed in the central nervous system, in excitatory and inhibitory neurons, and in astrocytes. CB1R agonists impair cognition and prevent long-term potentiation (LTP) of synaptic transmission, but the influence of endogenously formed cannabinoids (eCBs) on hippocampal LTP remains ambiguous. Based on the knowledge that eCBs are released upon high frequency neuronal firing, we hypothesized that the influence of eCBs upon LTP could change according to the paradigm of LTP induction. We thus tested the influence of eCBs on hippocampal LTP using two θ-burst protocols that induce either a weak or a strong LTP. LTP induced by a weak-θ-burst protocol is facilitated while preventing the endogenous activation of CB1Rs. In contrast, the same procedures lead to inhibition of LTP induced by the strong-θ-burst protocol, suggestive of a facilitatory action of eCBs upon strong LTP. Accordingly, an inhibitor of the metabolism of the predominant eCB in the hippocampus, 2-arachidonoyl-glycerol (2-AG), facilitates strong LTP. The facilitatory action of endogenous CB1R activation does not require the activity of inhibitory A1 adenosine receptors, is not affected by inhibition of astrocytic metabolism, but involves inhibitory GABAergic transmission. The continuous activation of CB1Rs via exogenous cannabinoids, or by drugs known to prevent metabolism of the non-prevalent hippocampal eCB, anandamide, inhibited LTP. We conclude that endogenous activation of CB1Rs by physiologically formed eCBs exerts a fine-tune homeostatic control of LTP in the hippocampus, acting as a high-pass filter, therefore likely reducing the signal-to-noise ratio of synaptic strengthening. PMID:29311928

Emergence Potential of Sylvatic Dengue Virus Type 4 in the Urban Transmission Cycle is Restrained by Vaccination and Homotypic Immunity

PubMed Central

Durbin, Anna P.; Mayer, Sandra V.; Rossi, Shannan L.; Amaya-Larios, Irma Y.; Ramos-Castaneda, Jose; Ooi, Eng Eong; Cardosa, M. Jane; Munoz-Jordan, Jorge L.; Tesh, Robert B.; Messer, William B.; Weaver, Scott C.; Vasilakis, Nikos

2013-01-01

Sylvatic dengue viruses (DENV) are both evolutionarily and ecologically distinct from human DENV and are maintained in an enzootic transmission cycle. Evidence of sylvatic human infections from West Africa and Southeast Asia suggests that sylvatic DENV come into regular contact with humans. Thus, this potential of emergence into the human transmission cycle could limit the potential for eradicating this cycle with vaccines currently in late stages of development. We assessed the likelihood of sylvatic DENV-4 emergence in the face of natural immunity to current human strains and vaccination with two DENV-4 vaccine candidates. Our data indicate homotypic neutralization of sylvatic and human DENV-4 strains by human primary convalescent and vaccinee sera but limited heterotypic immunity. These results suggest that emergence of sylvatic strains into the human cycle would be limited by homotypic immunity mediated by virus neutralizing antibodies produced by natural infection or vaccination. PMID:23485373

Continent-wide panmixia of an African fruit bat facilitates transmission of potentially zoonotic viruses.

PubMed

Peel, Alison J; Sargan, David R; Baker, Kate S; Hayman, David T S; Barr, Jennifer A; Crameri, Gary; Suu-Ire, Richard; Broder, Christopher C; Lembo, Tiziana; Wang, Lin-Fa; Fooks, Anthony R; Rossiter, Stephen J; Wood, James L N; Cunningham, Andrew A

2013-01-01

The straw-coloured fruit bat, Eidolon helvum, is Africa's most widely distributed and commonly hunted fruit bat, often living in close proximity to human populations. This species has been identified as a reservoir of potentially zoonotic viruses, but uncertainties remain regarding viral transmission dynamics and mechanisms of persistence. Here we combine genetic and serological analyses of populations across Africa, to determine the extent of epidemiological connectivity among E. helvum populations. Multiple markers reveal panmixia across the continental range, at a greater geographical scale than previously recorded for any other mammal, whereas populations on remote islands were genetically distinct. Multiple serological assays reveal antibodies to henipaviruses and Lagos bat virus in all locations, including small isolated island populations, indicating that factors other than population size and connectivity may be responsible for viral persistence. Our findings have potentially important public health implications, and highlight a need to avoid disturbances that may precipitate viral spillover.

Prosecution of non-disclosure of HIV status: Potential impact on HIV testing and transmission among HIV-negative men who have sex with men.

PubMed

Kesler, Maya A; Kaul, Rupert; Loutfy, Mona; Myers, Ted; Brunetta, Jason; Remis, Robert S; Gesink, Dionne

2018-01-01

Non-disclosure criminal prosecutions among gay, bisexual and other men who have sex with men (MSM) are increasing, even though transmission risk is low when effective antiretroviral treatment (ART) is used. Reduced HIV testing may reduce the impact of HIV "test and treat" strategies. We aimed to quantify the potential impact of non-disclosure prosecutions on HIV testing and transmission among MSM. MSM attending an HIV and primary care clinic in Toronto completed an audio computer-assisted self-interview questionnaire. HIV-negative participants were asked concern over non-disclosure prosecution altered their likelihood of HIV testing. Responses were characterized using cross-tabulations and bivariate logistic regressions. Flow charts modelled how changes in HIV testing behaviour impacted HIV transmission rates controlling for ART use, condom use and HIV status disclosure. 150 HIV-negative MSM were recruited September 2010 to June 2012. 7% (9/124) were less or much less likely to be tested for HIV due to concern over future prosecution. Bivariate regression showed no obvious socio/sexual demographic characteristics associated with decreased willingness of HIV testing to due concern about prosecution. Subsequent models estimated that this 7% reduction in testing could cause an 18.5% increase in community HIV transmission, 73% of which was driven by the failure of HIV-positive but undiagnosed MSM to access care and reduce HIV transmission risk by using ART. Fear of prosecution over HIV non-disclosure was reported to reduce HIV testing willingness by a minority of HIV-negative MSM in Toronto; however, this reduction has the potential to significantly increase HIV transmission at the community level which has important public health implications.

Prosecution of non-disclosure of HIV status: Potential impact on HIV testing and transmission among HIV-negative men who have sex with men

PubMed Central

Kaul, Rupert; Loutfy, Mona; Myers, Ted; Brunetta, Jason; Gesink, Dionne

2018-01-01

Background Non-disclosure criminal prosecutions among gay, bisexual and other men who have sex with men (MSM) are increasing, even though transmission risk is low when effective antiretroviral treatment (ART) is used. Reduced HIV testing may reduce the impact of HIV “test and treat” strategies. We aimed to quantify the potential impact of non-disclosure prosecutions on HIV testing and transmission among MSM. Methods MSM attending an HIV and primary care clinic in Toronto completed an audio computer-assisted self-interview questionnaire. HIV-negative participants were asked concern over non-disclosure prosecution altered their likelihood of HIV testing. Responses were characterized using cross-tabulations and bivariate logistic regressions. Flow charts modelled how changes in HIV testing behaviour impacted HIV transmission rates controlling for ART use, condom use and HIV status disclosure. Results 150 HIV-negative MSM were recruited September 2010 to June 2012. 7% (9/124) were less or much less likely to be tested for HIV due to concern over future prosecution. Bivariate regression showed no obvious socio/sexual demographic characteristics associated with decreased willingness of HIV testing to due concern about prosecution. Subsequent models estimated that this 7% reduction in testing could cause an 18.5% increase in community HIV transmission, 73% of which was driven by the failure of HIV-positive but undiagnosed MSM to access care and reduce HIV transmission risk by using ART. Conclusions Fear of prosecution over HIV non-disclosure was reported to reduce HIV testing willingness by a minority of HIV-negative MSM in Toronto; however, this reduction has the potential to significantly increase HIV transmission at the community level which has important public health implications. PMID:29489890

Transmission to interneurons is via slow excitatory synaptic potentials mediated by P2Y(1) receptors during descending inhibition in guinea-pig ileum.

PubMed

Thornton, Peter D J; Gwynne, Rachel M; McMillan, Darren J; Bornstein, Joel C

2013-01-01

The nature of synaptic transmission at functionally distinct synapses in intestinal reflex pathways has not been fully identified. In this study, we investigated whether transmission between interneurons in the descending inhibitory pathway is mediated by a purine acting at P2Y receptors to produce slow excitatory synaptic potentials (EPSPs). Myenteric neurons from guinea-pig ileum in vitro were impaled with intracellular microelectrodes. Responses to distension 15 mm oral to the recording site, in a separately perfused stimulation chamber and to electrical stimulation of local nerve trunks were recorded. A subset of neurons, previously identified as nitric oxide synthase immunoreactive descending interneurons, responded to both stimuli with slow EPSPs that were reversibly abolished by a high concentration of PPADS (30 μM, P2 receptor antagonist). When added to the central chamber of a three chambered organ bath, PPADS concentration-dependently depressed transmission through that chamber of descending inhibitory reflexes, measured as inhibitory junction potentials in the circular muscle of the anal chamber. Reflexes evoked by distension in the central chamber were unaffected. A similar depression of transmission was seen when the specific P2Y(1) receptor antagonist MRS 2179 (10 μM) was in the central chamber. Blocking either nicotinic receptors (hexamethonium 200 μM) or 5-HT(3) receptors (granisetron 1 μM) together with P2 receptors had no greater effect than blocking P2 receptors alone. Slow EPSPs mediated by P2Y(1) receptors, play a primary role in transmission between descending interneurons of the inhibitory reflexes in the guinea-pig ileum. This is the first demonstration for a primary role of excitatory metabotropic receptors in physiological transmission at a functionally identified synapse.

Anopheles (Diptera: Culicidae) malaria vectors in the municipality of Puerto Carreno, Vichada, Colombia

PubMed Central

Jiménez, Pilar; Conn, Jan E.; Wirtz, Robert; Brochero, Helena

2013-01-01

Introduction The study of the biological aspects of Anopheles spp., strengthens the entomological surveillance. Objective To determine biological aspects and behavior of adult Anopheles mosquitoes in the urban area of Puerto Carreño municipality, Vichada, Colombia. Materials and methods Wild anophelines were collected landing on humans both indoors and outdoors between 18:00h and 06:00h for 50 min/h during two consecutive nights/month for eight months in the urban area of Puerto Carreño. The biting rate activity, the natural infection by Plasmodium falciparum and P. vivax VK247 and VK210 using ELISA, and the annual entomological inoculation rate were determined for each species. The members of the Albitarsis complex were determined by amplificacion of the white gene by polymerase chain reaction. Results In order of abundance the species found were An. darlingi (n=1,166), An. marajoara sensu stricto (n=152), An. braziliensis (n=59), An. albitarsis F (n=25), An. albitarsis sensu lato (n=16), An. argyritarsis (n=3) and An. oswaldoi sensu lato (n=2). An. darlingi showed two activity peaks between 21:00 to 22:00 and 05:00 to 06:00 hours outdoors and between 21:00 to 22:00 and 04:00 to 05:00 indoors. Natural infection of this species was found with P. vivax VK210 and its annual entomological inoculation rate was 2. Natural infection of An marajoara sensu stricto with P. falciparum was found, with an annual entomological inoculation rate of 5 and a peak biting activity between 18:00 to 19:00 hrs both indoors and outdoors. Conclusion Transmission of malaria in the urban area of Puerto Carreño, Vichada, can occur by An. darlingi and An. marajoara s. s. PMID:23235809

Preliminary observations on the changing roles of malaria vectors in southern Belize.

PubMed

Roberts, D R; Chan, O; Pecor, J; Rejmankova, E; Manguin, S; Polanco, J; Legters, L J

1993-12-01

A survey for larval and adult Anopheles mosquitoes was conducted in Toledo District of southern Belize during August-September 1992. We surveyed for larvae in 145 habitats and conducted paired indoor-outdoor collections of adult mosquitoes landing on humans at 6 houses. In 1940-41, Kumm and Ram reported Anopheles darlingi females to be the most common Anopheles mosquitoes inside houses and reported no specimens of Anopheles vestitipennis in southern Belize. In our 1992 survey we found no An. darlingi mosquitoes either as adults or larvae. More An. vestitipennis females were captured indoors than outdoors, whereas most Anopheles albimanus and Anopheles apicimacula females were captured outdoors. All 3 species were represented occasionally in 145 collections of larvae from diverse habitats. Anopheles vestitipennis now appears to be a potentially important vector of malaria during the wet season in Toledo District.

Neurogranin restores amyloid β-mediated synaptic transmission and long-term potentiation deficits.

PubMed

Kaleka, Kanwardeep Singh; Gerges, Nashaat Z

2016-03-01

Amyloid β (Aβ) is widely considered one of the early causes of cognitive deficits observed in Alzheimer's disease. Many of the deficits caused by Aβ are attributed to its disruption of synaptic function represented by its blockade of long-term potentiation (LTP) and its induction of synaptic depression. Identifying pathways that reverse these synaptic deficits may open the door to new therapeutic targets. In this study, we explored the possibility that Neurogranin (Ng)-a postsynaptic calmodulin (CaM) targeting protein that enhances synaptic function-may rescue Aβ-mediated deficits in synaptic function. Our results show that Ng is able to reverse synaptic depression and LTP deficits induced by Aβ. Furthermore, Ng's restoration of synaptic transmission is through the insertion of GluA1-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptors (AMPARs). These restorative effects of Ng are dependent on the interaction of Ng and CaM and CaM-dependent activation of CaMKII. Overall, this study identifies a novel mechanism to rescue synaptic deficits induced by Aβ oligomers. It also suggests Ng and CaM signaling as potential therapeutic targets for Alzheimer's disease as well as important tools to further explore the pathophysiology underlying the disease. Copyright © 2015 Elsevier Inc. All rights reserved.

Expert systems in transmission planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galiana, F.D.; McGillis, D.T.; Marin, M.A.

1992-05-01

In this paper the state of the field of expert systems and knowledge engineering in transmission planning is reviewed. A detailed analysis of the goals, definition, requirements and methodology of transmission planning is presented. Potential benefits of knowledge-based applications in transmission planning are reviewed. This is followed by a thorough review of the area broken down into subareas or important related topics. The conclusions offer a number of suggestions for possible future research and development. Finally, a detailed bibliography divided into subareas is presented.

Transmissible Spongiform Encephalopathy and Meat Safety

NASA Astrophysics Data System (ADS)

Ward, Hester J. T.; Knight, Richard S. G.

Prion diseases or transmissible spongiform encephalopathies (TSEs) comprise a wide-ranging group of neurodegenerative diseases found in animals and humans. They have diverse causes and geographical distributions, but have similar pathological features, transmissibility and, are ultimately, fatal. Central to all TSEs is the presence of an abnormal form of a normal host protein, namely the prion protein. Because of their potential transmissibility, these diseases have wide public health ramifications.

Infectious Disease Transmission during Organ and Tissue Transplantation

PubMed Central

Kuehnert, Matthew J.; Fishman, Jay A.

2012-01-01

Infectious disease transmission through organ and tissue transplantation has been associated with severe complications in recipients. Determination of donor-derived infectious risk associated with organ and tissue transplantation is challenging and limited by availability and performance characteristics of current donor epidemiologic screening (e.g., questionnaire) and laboratory testing tools. Common methods and standards for evaluating potential donors of organs and tissues are needed to facilitate effective data collection for assessing the risk for infectious disease transmission. Research programs can use advanced microbiological technologies to define infectious risks posed by pathogens that are known to be transplant transmissible and provide insights into transmission potential of emerging infectious diseases for which transmission characteristics are unknown. Key research needs are explored. Stakeholder collaboration for surveillance and research infrastructure is required to enhance transplant safety. PMID:22840823

Beyond Massive MIMO: The Potential of Data Transmission With Large Intelligent Surfaces

NASA Astrophysics Data System (ADS)

Hu, Sha; Rusek, Fredrik; Edfors, Ove

2018-05-01

In this paper, we consider the potential of data-transmission in a system with a massive number of radiating and sensing elements, thought of as a contiguous surface of electromagnetically active material. We refer to this as a large intelligent surface (LIS). The "LIS" is a newly proposed concept, which conceptually goes beyond contemporary massive MIMO technology, that arises from our vision of a future where man-made structures are electronically active with integrated electronics and wireless communication making the entire environment "intelligent". We consider capacities of single-antenna autonomous terminals communicating to the LIS where the entire surface is used as a receiving antenna array. Under the condition that the surface-area is sufficiently large, the received signal after a matched-filtering (MF) operation can be closely approximated by a sinc-function-like intersymbol interference (ISI) channel. We analyze the capacity per square meter (m^2) deployed surface, \\hat{C}, that is achievable for a fixed transmit power per volume-unit, \\hat{P}. Moreover, we also show that the number of independent signal dimensions per m deployed surface is 2/\\lambda for one-dimensional terminal-deployment, and \\pi/\\lambda^2 per m^2 for two and three dimensional terminal-deployments. Lastly, we consider implementations of the LIS in the form of a grid of conventional antenna elements and show that, the sampling lattice that minimizes the surface-area of the LIS and simultaneously obtains one signal space dimension for every spent antenna is the hexagonal lattice. We extensively discuss the design of the state-of-the-art low-complexity channel shortening (CS) demodulator for data-transmission with the LIS.

Electronic transmission in non-linear potential profile of GaAs/AlxGa1-xAs biased quantum well structure

NASA Astrophysics Data System (ADS)

Meghoufel, F. Z.; Bentata, S.; Terkhi, S.; Bendahma, F.; Cherid, S.

2013-05-01

We study the effect of the nonlinearity on electrons transmission properties in a double barriers structure GaAs/AlxGa1-xAs superlattices. The nonlinearity is introduced as an effective potential in the Schrödinger equation and translates the electronic Colombian repulsion. We have used the transfer matrix formalism and the plane wave functions approximation to solve numerically the equation and calculate the electronic transmission coefficient. We have shown the occurrence of two allowed states within the same well instead of a single, translating the presence of two resonant states at two different energies. The first allowed state intensity strongly decreases with increasing the nonlinear parameter, whereas the second one called the degeneracy state increases. Both the two states evolve towards higher resonances energies.

Parasite transmission in a natural multihost-multiparasite community.

PubMed

Auld, Stuart K J R; Searle, Catherine L; Duffy, Meghan A

2017-05-05

Understanding the transmission and dynamics of infectious diseases in natural communities requires understanding the extent to which the ecology, evolution and epidemiology of those diseases are shaped by alternative hosts. We performed laboratory experiments to test how parasite spillover affected traits associated with transmission in two co-occurring parasites: the bacterium Pasteuria ramosa and the fungus Metschnikowia bicuspidata Both parasites were capable of transmission from the reservoir host ( Daphnia dentifera ) to the spillover host ( Ceriodaphnia dubia ), but this occurred at a much higher rate for the fungus than the bacterium. We quantified transmission potential by combining information on parasite transmission and growth rate, and used this to compare parasite fitness in the two host species. For both parasites, transmission potential was lower in the spillover host. For the bacterium, virulence was higher in the spillover host. Transmission back to the original host was high for both parasites, with spillover influencing transmission rate of the fungus but not the bacterium. Thus, while inferior, the spillover host is not a dead-end for either parasite. Overall, our results demonstrate that the presence of multiple hosts in a community can have important consequences for disease transmission, and host and parasite fitness.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'. © 2017 The Author(s).

Species composition and natural infectivity of anthropophilic Anopheles (Diptera: Culicidae) in Córdoba and Antioquia states in northwestern Colombia

PubMed Central

Gutiérrez, Lina A; González, John J; Gómez, Giovan F; Castro, Martha I; Rosero, Doris A; Luckhart, Shirley; Conn, Jan E; Correa, Margarita M

2011-01-01

Malaria is a serious health problem in Córdoba and Antioquia states in northwestern Colombia, where 64.4% of the total Colombian cases were reported in 2007. Because little entomological information is available in this region, the aim of this work was to identify the Anopheles species composition and natural infectivity of mosquitoes distributed in seven localities with the highest malaria transmission. A total of 1,768 Anopheles mosquitoes were collected using human landing catches from March 2007 to July 2008. Ten species were identified; overall, An. nuneztovari s.l. was the most widespread (62%) and showed the highest average human biting rates. There were six other species of the Nyssorhynchus subgenus: An. albimanus (11.6%), An. darlingi (9.8%), An. braziliensis (6.6%), An. triannulatus s.l. (3.5%), An. albitarsis s.l. and An. oswaldoi s.l. at <1%; and three of the Anopheles subgenus: An. punctimacula, An. pseudopunctipennis s.l. and An. neomaculipalpus at <1% each. Two species from Córdoba, An. nuneztovari and An. darlingi, were detected naturally infected by Plasmodium vivax VK247 using ELISA and confirmed by nested PCR. All species were active indoors and outdoors. These results provide basic information for targeted vector control strategies in these localities. PMID:20140372

Anophelines species and the receptivity and vulnerability to malaria transmission in the Pantanal wetlands, Central Brazil

PubMed Central

Marinho-e-Silva, Mariana; Sallum, Maria Anice Mureb; Rosa-Freitas, Maria Goreti; Lourenço-de-Oliveira, Ricardo; Silva-do-Nascimento, Teresa Fernandes

2018-01-01

BACKGROUND Studies on malaria vectors in the Pantanal biome, Central Brazil, were conducted more than half a century ago. OBJECTIVES To update anopheline records and assess receptivity and vulnerability to malaria transmission. METHODS Five-day anopheline collections were conducted bimonthly in Salobra, Mato Grosso do Sul state, for one year. Indoors, mosquitoes were collected from their resting places, while in open fields, they were captured using protected human-baited and horse-baited traps near the house and at the Miranda River margin, respectively. Hourly biting activity outdoors was also assessed. Secondary data were collected on the arrival of tourists, economic projects, and malaria cases. FINDINGS A total of 24,894 anophelines belonging to 13 species were caught. The main Brazilian malaria vector Anopheles darlingi was the predominant species, followed by An. triannulatus s.l. Hourly variation in anopheline biting showed three main peaks occurring at sunset, around midnight, and at sunrise, the first and last being the most prominent. The highest density of all species was recorded near the river margin and during the transition period between the rainy and early dry seasons. This coincides with the time of main influx of outsider workers and tourists, whose activities mostly occur in the open fields and frequently start before sunrise and last until sunset. Some of these individuals originate from neighbouring malaria-endemic countries and states, and are likely responsible for the recorded imported and introduced malaria cases. MAIN CONCLUSION Pantanal is a malaria-prone area in Brazil. Surveillance and anopheline control measures must be applied to avoid malaria re-emergence in the region. PMID:29236930

Schools as Potential Risk Sites for Vector-Borne Disease Transmission: Mosquito Vectors in Rural Schools in Two Municipalities in Colombia.

PubMed

Olano, Víctor Alberto; Matiz, María Inés; Lenhart, Audrey; Cabezas, Laura; Vargas, Sandra Lucía; Jaramillo, Juan Felipe; Sarmiento, Diana; Alexander, Neal; Stenström, Thor Axel; Overgaard, Hans J

2015-09-01

Dengue and other vector-borne diseases are of great public health importance in Colombia. Vector surveillance and control activities are often focused at the household level. Little is known about the importance of nonhousehold sites, including schools, in maintaining vector-borne disease transmission. The objectives of this paper were to determine the mosquito species composition in rural schools in 2 municipalities in Colombia and to assess the potential risk of vector-borne disease transmission in school settings. Entomological surveys were carried out in rural schools during the dry and rainy seasons of 2011. A total of 12 mosquito species were found: Aedes aegypti, Anopheles pseudopunctipennis, Culex coronator, Cx. quinquefasciatus, and Limatus durhamii in both immature and adult forms; Ae. fluviatilis, Cx. nigripalpus, Cx. corniger, and Psorophora ferox in immature forms only; and Ae. angustivittatus, Haemagogus equinus, and Trichoprosopon lampropus in adult forms only. The most common mosquito species was Cx. quinquefasciatus. Classrooms contained the greatest abundance of adult female Ae. aegypti and Cx. quinquefasciatus. The most common Ae. aegypti breeding sites were containers classified as "others" (e.g., cans), followed by containers used for water storage. A high level of Ae. aegypti infestation was found during the wet season. Our results suggest that rural schools are potentially important foci for the transmission of dengue and other mosquito-borne diseases. We propose that public health programs should be implemented in rural schools to prevent vector-borne diseases.

The reporting of theoretical health risks by the media: Canadian newspaper reporting of potential blood transmission of Creutzfeldt-Jakob disease

PubMed Central

Wilson, Kumanan; Code, Catherine; Dornan, Christopher; Ahmad, Nadya; Hébert, Paul; Graham, Ian

2004-01-01

Background The media play an important role at the interface of science and policy by communicating scientific information to the public and policy makers. In issues of theoretical risk, in which there is scientific uncertainty, the media's role as disseminators of information is particularly important due to the potential to influence public perception of the severity of the risk. In this article we describe how the Canadian print media reported the theoretical risk of blood transmission of Creutzfeldt-Jakob disease (CJD). Methods We searched 3 newspaper databases for articles published by 6 major Canadian daily newspapers between January 1990 and December 1999. We identified all articles relating to blood transmission of CJD. In duplicate we extracted information from the articles and entered the information into a qualitative software program. We compared the observations obtained from this content analysis with information obtained from a previous policy analysis examining the Canadian blood system's decision-making concerning the potential transfusion transmission of CJD. Results Our search identified 245 relevant articles. We observed that newspapers in one instance accelerated a policy decision, which had important resource and health implication, by communicating information on risk to the public. We also observed that newspapers primarily relied upon expert opinion (47 articles) as opposed to published medical evidence (28 articles) when communicating risk information. Journalists we interviewed described the challenges of balancing their responsibility to raise awareness of potential health threats with not unnecessarily arousing fear amongst the public. Conclusions Based on our findings we recommend that journalists report information from both expert opinion sources and from published studies when communicating information on risk. We also recommend researchers work more closely with journalists to assist them in identifying and appraising relevant

Potential for Zika virus introduction and transmission in resource-limited countries in Africa and the Asia-Pacific region: a modelling study.

PubMed

Bogoch, Isaac I; Brady, Oliver J; Kraemer, Moritz U G; German, Matthew; Creatore, Maria I; Brent, Shannon; Watts, Alexander G; Hay, Simon I; Kulkarni, Manisha A; Brownstein, John S; Khan, Kamran

2016-11-01

As the epidemic of Zika virus expands in the Americas, countries across Africa and the Asia-Pacific region are becoming increasingly susceptible to the importation and possible local spread of the virus. To support public health readiness, we aim to identify regions and times where the potential health, economic, and social effects from Zika virus are greatest, focusing on resource-limited countries in Africa and the Asia-Pacific region. Our model combined transportation network analysis, ecological modelling of mosquito occurrences, and vector competence for flavivirus transmission, using data from the International Air Transport Association, entomological observations from Zika's primary vector species, and climate conditions using WorldClim. We overlaid monthly flows of airline travellers arriving to Africa and the Asia-Pacific region from areas of the Americas suitable for year-round transmission of Zika virus with monthly maps of climatic suitability for mosquito-borne transmission of Zika virus within Africa and the Asia-Pacific region. An estimated 2·6 billion people live in areas of Africa and the Asia-Pacific region where the presence of competent mosquito vectors and suitable climatic conditions could support local transmission of Zika virus. Countries with large volumes of travellers arriving from Zika virus-affected areas of the Americas and large populations at risk of mosquito-borne Zika virus infection include India (67 422 travellers arriving per year; 1·2 billion residents in potential Zika transmission areas), China (238 415 travellers; 242 million residents), Indonesia (13 865 travellers; 197 million residents), Philippines (35 635 travellers; 70 million residents), and Thailand (29 241 travellers; 59 million residents). Many countries across Africa and the Asia-Pacific region are vulnerable to Zika virus. Strategic use of available health and human resources is essential to prevent or mitigate the health, economic, and social

Parasite transmission in a natural multihost–multiparasite community

PubMed Central

2017-01-01

Understanding the transmission and dynamics of infectious diseases in natural communities requires understanding the extent to which the ecology, evolution and epidemiology of those diseases are shaped by alternative hosts. We performed laboratory experiments to test how parasite spillover affected traits associated with transmission in two co-occurring parasites: the bacterium Pasteuria ramosa and the fungus Metschnikowia bicuspidata. Both parasites were capable of transmission from the reservoir host (Daphnia dentifera) to the spillover host (Ceriodaphnia dubia), but this occurred at a much higher rate for the fungus than the bacterium. We quantified transmission potential by combining information on parasite transmission and growth rate, and used this to compare parasite fitness in the two host species. For both parasites, transmission potential was lower in the spillover host. For the bacterium, virulence was higher in the spillover host. Transmission back to the original host was high for both parasites, with spillover influencing transmission rate of the fungus but not the bacterium. Thus, while inferior, the spillover host is not a dead-end for either parasite. Overall, our results demonstrate that the presence of multiple hosts in a community can have important consequences for disease transmission, and host and parasite fitness. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289264

Live Animal Markets in Minnesota: A Potential Source for Emergence of Novel Influenza A Viruses and Interspecies Transmission

PubMed Central

Choi, Mary J.; Torremorell, Montserrat; Bender, Jeff B.; Smith, Kirk; Boxrud, David; Ertl, Jon R.; Yang, My; Suwannakarn, Kamol; Her, Duachi; Nguyen, Jennifer; Uyeki, Timothy M.; Levine, Min; Lindstrom, Stephen; Katz, Jacqueline M.; Jhung, Michael; Vetter, Sara; Wong, Karen K.; Sreevatsan, Srinand; Lynfield, Ruth

2015-01-01

Background. Live animal markets have been implicated in transmission of influenza A viruses (IAVs) from animals to people. We sought to characterize IAVs at 2 live animal markets in Minnesota to assess potential routes of occupational exposure and risk for interspecies transmission. Methods. We implemented surveillance for IAVs among employees, swine, and environment (air and surfaces) during a 12-week period (October 2012–January 2013) at 2 markets epidemiologically associated with persons with swine-origin IAV (variant) infections. Real-time reverse transcription polymerase chain reaction (rRT-PCR), viral culture, and whole-genome sequencing were performed on respiratory and environmental specimens, and serology on sera from employees at beginning and end of surveillance. Results. Nasal swabs from 11 of 17 (65%) employees tested positive for IAVs by rRT-PCR; 7 employees tested positive on multiple occasions and 1 employee reported influenza-like illness. Eleven of 15 (73%) employees had baseline hemagglutination inhibition antibody titers ≥40 to swine-origin IAVs, but only 1 demonstrated a 4-fold titer increase to both swine-origin and pandemic A/Mexico/4108/2009 IAVs. IAVs were isolated from swine (72/84), air (30/45), and pen railings (5/21). Whole-genome sequencing of 122 IAVs isolated from swine and environmental specimens revealed multiple strains and subtype codetections. Multiple gene segment exchanges among and within subtypes were observed, resulting in new genetic constellations and reassortant viruses. Genetic sequence similarities of 99%–100% among IAVs of 1 market customer and swine indicated interspecies transmission. Conclusions. At markets where swine and persons are in close contact, swine-origin IAVs are prevalent and potentially provide conditions for novel IAV emergence. PMID:26223994

Live Animal Markets in Minnesota: A Potential Source for Emergence of Novel Influenza A Viruses and Interspecies Transmission.

PubMed

Choi, Mary J; Torremorell, Montserrat; Bender, Jeff B; Smith, Kirk; Boxrud, David; Ertl, Jon R; Yang, My; Suwannakarn, Kamol; Her, Duachi; Nguyen, Jennifer; Uyeki, Timothy M; Levine, Min; Lindstrom, Stephen; Katz, Jacqueline M; Jhung, Michael; Vetter, Sara; Wong, Karen K; Sreevatsan, Srinand; Lynfield, Ruth

2015-11-01

Live animal markets have been implicated in transmission of influenza A viruses (IAVs) from animals to people. We sought to characterize IAVs at 2 live animal markets in Minnesota to assess potential routes of occupational exposure and risk for interspecies transmission. We implemented surveillance for IAVs among employees, swine, and environment (air and surfaces) during a 12-week period (October 2012-January 2013) at 2 markets epidemiologically associated with persons with swine-origin IAV (variant) infections. Real-time reverse transcription polymerase chain reaction (rRT-PCR), viral culture, and whole-genome sequencing were performed on respiratory and environmental specimens, and serology on sera from employees at beginning and end of surveillance. Nasal swabs from 11 of 17 (65%) employees tested positive for IAVs by rRT-PCR; 7 employees tested positive on multiple occasions and 1 employee reported influenza-like illness. Eleven of 15 (73%) employees had baseline hemagglutination inhibition antibody titers ≥40 to swine-origin IAVs, but only 1 demonstrated a 4-fold titer increase to both swine-origin and pandemic A/Mexico/4108/2009 IAVs. IAVs were isolated from swine (72/84), air (30/45), and pen railings (5/21). Whole-genome sequencing of 122 IAVs isolated from swine and environmental specimens revealed multiple strains and subtype codetections. Multiple gene segment exchanges among and within subtypes were observed, resulting in new genetic constellations and reassortant viruses. Genetic sequence similarities of 99%-100% among IAVs of 1 market customer and swine indicated interspecies transmission. At markets where swine and persons are in close contact, swine-origin IAVs are prevalent and potentially provide conditions for novel IAV emergence. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Frequency and patterns of contact with domestic poultry and potential risk of H5N1 transmission to humans living in rural Cambodia

PubMed Central

Van Kerkhove, Maria D.; Ly, Sowath; Holl, Davun; Guitian, Javier; Mangtani, Punam; Ghani, Azra C.; Vong, Sirenda

2008-01-01

Background  Since 2004, H5N1 outbreaks have been recurrent in domestic poultry and humans in Cambodia. To date, seven human cases (100% CFR) and 22 outbreaks in poultry have been confirmed. Household ownership of backyard poultry (FAO Sector 4 poultry production) in rural Cambodia is high. An understanding of the extent and frequency of poultry handing behaviors in these settings is necessary to assess the risk associated with different practices and to formulate sensible recommendations to mitigate this risk. We collected new data from six geographic regions to examine patterns of human contact with poultry among rural farmers in Cambodia and identify populations with the highest potential exposure to H5N1. Methods and Findings  A cross‐sectional survey was undertaken in which 3,600 backyard poultry owners from 115 randomly selected villages in six provinces throughout Cambodia were interviewed. Using risk assessment methods, patterns of contact with poultry as surrogate measures of exposure to H5N1 were used to generate risk indices of potential H5N1 transmission to different populations in contact with poultry. Estimates of human exposure risk for each study participant (n = 3600) were obtained by multiplying each reported practice with a transmission risk‐weighting factor and summing these over all practices reported by each individual. Exposure risk estimates were then examined stratified by age and gender. Subjects reported high contact with domestic poultry (chickens and ducks) through the daily care and food preparation practices, however contact patterns varied by gender and age. Males between the ages of 26‐40 reported practices of contact with poultry that give rise to the highest H5N1 transmission risk potential, followed closely by males between the ages of 16‐25. Overall, males had a higher exposure risk potential than females across all age groups (p < 0·001). Conclusions  Our results demonstrate that most of the population in

Potential Application of Digitally Linked Tuberculosis Diagnostics for Real-Time Surveillance of Drug-Resistant Tuberculosis Transmission: Validation and Analysis of Test Results.

PubMed

Ng, Kamela Charmaine; Meehan, Conor Joseph; Torrea, Gabriela; Goeminne, Léonie; Diels, Maren; Rigouts, Leen; de Jong, Bouke Catherine; André, Emmanuel

2018-02-27

Tuberculosis (TB) is the highest-mortality infectious disease in the world and the main cause of death related to antimicrobial resistance, yet its surveillance is still paper-based. Rifampicin-resistant TB (RR-TB) is an urgent public health crisis. The World Health Organization has, since 2010, endorsed a series of rapid diagnostic tests (RDTs) that enable rapid detection of drug-resistant strains and produce large volumes of data. In parallel, most high-burden countries have adopted connectivity solutions that allow linking of diagnostics, real-time capture, and shared repository of these test results. However, these connected diagnostics and readily available test results are not used to their full capacity, as we have yet to capitalize on fully understanding the relationship between test results and specific rpoB mutations to elucidate its potential application to real-time surveillance. We aimed to validate and analyze RDT data in detail, and propose the potential use of connected diagnostics and associated test results for real-time evaluation of RR-TB transmission. We selected 107 RR-TB strains harboring 34 unique rpoB mutations, including 30 within the rifampicin resistance-determining region (RRDR), from the Belgian Coordinated Collections of Microorganisms, Antwerp, Belgium. We subjected these strains to Xpert MTB/RIF, GenoType MTBDRplus v2.0, and Genoscholar NTM + MDRTB II, the results of which were validated against the strains' available rpoB gene sequences. We determined the reproducibility of the results, analyzed and visualized the probe reactions, and proposed these for potential use in evaluating transmission. The RDT probe reactions detected most RRDR mutations tested, although we found a few critical discrepancies between observed results and manufacturers' claims. Based on published frequencies of probe reactions and RRDR mutations, we found specific probe reactions with high potential use in transmission studies: Xpert MTB/RIF probes A

Alteration of plant species assemblages can decrease the transmission potential of malaria mosquitoes.

PubMed

Ebrahimi, Babak; Jackson, Bryan T; Guseman, Julie L; Przybylowicz, Colin M; Stone, Christopher M; Foster, Woodbridge A

2018-03-01

Knowledge of the link between a vector population's pathogen-transmission potential and its biotic environment can generate more realistic forecasts of disease risk due to environmental change. It also can promote more effective vector control by both conventional and novel means.This study assessed the effect of particular plant species assemblages differing in nectar production on components of the vectorial capacity of the mosquito Anopheles gambiae s.s. , an important vector of African malaria.We followed cohorts of mosquitoes for three weeks in greenhouse mesocosms holding nectar-poor and nectar-rich plant species by tracking daily mortalities and estimating daily biting rates and fecundities. At death, a mosquito's insemination status and wing length were determined. These life history traits allowed incorporation of larval dynamics into a vectorial capacity estimate. This new study provided both novel assemblages of putative host plants and a human blood host within a nocturnal period of maximum biting.Survivorship was significantly greater in nectar-rich environments than nectar-poor ones, resulting in greater total fecundity. Daily biting rate and fecundity per female between treatments was not detected. These results translated to greater estimated vectorial capacities in the nectar-rich environment in all four replicates of the experiment (means: 1,089.5 ± 125.2 vs. 518.3 ± 60.6). When mosquito density was made a function of survival and fecundity, rather than held constant, the difference between plant treatments was more pronounced, but so was the variance, so differences were not statistically significant. In the nectar-poor environment, females' survival suffered severely when a blood host was not provided. A sugar-accessibility experiment confirmed that Parthenium hysterophorus is a nectar-poor plant for these mosquitoes. Synthesis and applications. This study, assessing the effect of particular plant species assemblages on the vectorial capacity

Potential geographic "hotspots" for drug-injection related transmission of HIV and HCV and for initiation into injecting drug use in New York City, 2011-2015, with implications for the current opioid epidemic in the US.

PubMed

Des Jarlais, D C; Cooper, H L F; Arasteh, K; Feelemyer, J; McKnight, C; Ross, Z

2018-01-01

We identified potential geographic "hotspots" for drug-injecting transmission of HIV and hepatitis C virus (HCV) among persons who inject drugs (PWID) in New York City. The HIV epidemic among PWID is currently in an "end of the epidemic" stage, while HCV is in a continuing, high prevalence (> 50%) stage. We recruited 910 PWID entering Mount Sinai Beth Israel substance use treatment programs from 2011-2015. Structured interviews and HIV/ HCV testing were conducted. Residential ZIP codes were used as geographic units of analysis. Potential "hotspots" for HIV and HCV transmission were defined as 1) having relatively large numbers of PWID 2) having 2 or more HIV (or HCV) seropositive PWID reporting transmission risk-passing on used syringes to others, and 3) having 2 or more HIV (or HCV) seronegative PWID reporting acquisition risk-injecting with previously used needles/syringes. Hotspots for injecting drug use initiation were defined as ZIP codes with 5 or more persons who began injecting within the previous 6 years. Among PWID, 96% injected heroin, 81% male, 34% White, 15% African-American, 47% Latinx, mean age 40 (SD = 10), 7% HIV seropositive, 62% HCV seropositive. Participants resided in 234 ZIP codes. No ZIP codes were identified as potential hotspots due to small numbers of HIV seropositive PWID reporting transmission risk. Four ZIP codes were identified as potential hotspots for HCV transmission. 12 ZIP codes identified as hotspots for injecting drug use initiation. For HIV, the lack of potential hotspots is further validation of widespread effectiveness of efforts to reduce injecting-related HIV transmission. Injecting-related HIV transmission is likely to be a rare, random event. HCV prevention efforts should include focus on potential hotspots for transmission and on hotspots for initiation into injecting drug use. We consider application of methods for the current opioid epidemic in the US.

Assessing the Potential Impact of Hormonal-Based Contraceptives on HIV Transmission Dynamics Among Heterosexuals.

PubMed

Malunguza, Noble J; Hove-Musekwa, Senelani D; Mukandavire, Zindoga

2017-04-01

HIV susceptibility linked to hormonal contraception (HC) has been studied before, but with mixed results. Reports from some of the recent findings have prompted the World Health Organisation to encourage women who use HC to concurrently use condoms in order to prevent HIV infection in the light of possible increased HIV risk of infection associated with hormone-based contraceptives. A two-sex HIV model classifying women into three risk groups consisting of individuals who use condoms, natural methods, and hormone-based contraceptives is formulated and analysed to assess the possible effects of various birth control strategies on the transmission dynamics of the disease. Our model results showed that women who use HC could be key drivers of the epidemic and that their increased infectivity may be critical in driving the epidemic. Women who use hormone-based contraceptives potentially act as a core group from which men get infected and in turn transmit the disease to other population groups. We fitted the model to HIV prevalence data for Zimbabwe reported by UNAIDS and Zimbabwe Ministry of Health and Child Care and used the model fit to project HIV prevalence. Predictions using HIV data for Zimbabwe suggest that a hypothesised increase in susceptibility and infectivity of two-, three-, and fourfold would result in a 25, 50, and 100% increase in baseline HIV prevalence projection, respectively, thus suggesting possible increased disease burden even in countries reporting plausible HIV prevalence declines. Although a possible causal relationship between HIV susceptibility and HC use remains subject of continuing scientific probe, its inclusion as part of birth control strategy has been shown in this study, to possibly increase HIV transmission. If proven, HC use may potentially explain the inordinate spread of HIV within the sub-Saharan Africa region and therefore compel for urgent assessment with a view to reorienting birth control methods in use in settings with

Nipah virus transmission in a hamster model.

PubMed

de Wit, Emmie; Bushmaker, Trenton; Scott, Dana; Feldmann, Heinz; Munster, Vincent J

2011-12-01

Based on epidemiological data, it is believed that human-to-human transmission plays an important role in Nipah virus outbreaks. No experimental data are currently available on the potential routes of human-to-human transmission of Nipah virus. In a first dose-finding experiment in Syrian hamsters, it was shown that Nipah virus was predominantly shed via the respiratory tract within nasal and oropharyngeal secretions. Although Nipah viral RNA was detected in urogenital and rectal swabs, no infectious virus was recovered from these samples, suggesting no viable virus was shed via these routes. In addition, hamsters inoculated with high doses shed significantly higher amounts of viable Nipah virus particles in comparison with hamsters infected with lower inoculum doses. Using the highest inoculum dose, three potential routes of Nipah virus transmission were investigated in the hamster model: transmission via fomites, transmission via direct contact and transmission via aerosols. It was demonstrated that Nipah virus is transmitted efficiently via direct contact and inefficiently via fomites, but not via aerosols. These findings are in line with epidemiological data which suggest that direct contact with nasal and oropharyngeal secretions of Nipah virus infected individuals resulted in greater risk of Nipah virus infection. The data provide new and much-needed insights into the modes and efficiency of Nipah virus transmission and have important public health implications with regards to the risk assessment and management of future Nipah virus outbreaks.

Nipah Virus Transmission in a Hamster Model

PubMed Central

de Wit, Emmie; Bushmaker, Trenton; Scott, Dana; Feldmann, Heinz; Munster, Vincent J.

2011-01-01

Based on epidemiological data, it is believed that human-to-human transmission plays an important role in Nipah virus outbreaks. No experimental data are currently available on the potential routes of human-to-human transmission of Nipah virus. In a first dose-finding experiment in Syrian hamsters, it was shown that Nipah virus was predominantly shed via the respiratory tract within nasal and oropharyngeal secretions. Although Nipah viral RNA was detected in urogenital and rectal swabs, no infectious virus was recovered from these samples, suggesting no viable virus was shed via these routes. In addition, hamsters inoculated with high doses shed significantly higher amounts of viable Nipah virus particles in comparison with hamsters infected with lower inoculum doses. Using the highest inoculum dose, three potential routes of Nipah virus transmission were investigated in the hamster model: transmission via fomites, transmission via direct contact and transmission via aerosols. It was demonstrated that Nipah virus is transmitted efficiently via direct contact and inefficiently via fomites, but not via aerosols. These findings are in line with epidemiological data which suggest that direct contact with nasal and oropharyngeal secretions of Nipah virus infected individuals resulted in greater risk of Nipah virus infection. The data provide new and much-needed insights into the modes and efficiency of Nipah virus transmission and have important public health implications with regards to the risk assessment and management of future Nipah virus outbreaks. PMID:22180802

SURVIVAL AND TRANSMISSION OF PATHOGENS IN THE ENVIRONMENT

EPA Science Inventory

To provide and apply scientific knowledge regarding the survival and transmission of pathogens in the clinical setting to their potential survival and transmission in the natural environment. Similar to the hospital environment where pathogens reside in organic debris treated wi...

Transmission eigenvalues

NASA Astrophysics Data System (ADS)

Cakoni, Fioralba; Haddar, Houssem

2013-10-01

associated transmission eigenfunctions. The three papers by respectively Robbiano [11], Blasten and Päivärinta [12], and Lakshtanov and Vainberg [13] provide new complementary results on the existence of transmission eigenvalues for the scalar problem under weak assumptions on the (possibly complex valued) refractive index that mainly stipulates that the contrast does not change sign on the boundary. It is interesting here to see three different new methods to obtain these results. On the other hand, the paper by Bonnet-Ben Dhia and Chesnel [14] addresses the Fredholm properties of the interior transmission problem when the contrast changes sign on the boundary, exhibiting cases where this property fails. Using more standard approaches, the existence and structure of transmission eigenvalues are analyzed in the paper by Delbary [15] for the case of frequency dependent materials in the context of Maxwell's equations, whereas the paper by Vesalainen [16] initiates the study of the transmission eigenvalue problem in unbounded domains by considering the transmission eigenvalues for Schrödinger equation with non-compactly supported potential. The paper by Monk and Selgas [17] addresses the case where the dielectric is mounted on a perfect conductor and provides some numerical examples of the localization of associated eigenvalues using the linear sampling method. A series of papers then addresses the question of localization of transmission eigenvalues and the associated inverse spectral problem for spherically stratified media. More specifically, the paper by Colton and Leung [18] provides new results on complex transmission eigenvalues and a new proof for uniqueness of a solution to the inverse spectral problem, whereas the paper by Sylvester [19] provides sharp results on how to locate all the transmission eigenvalues associated with angular independent eigenfunctions when the index of refraction is constant. The paper by Gintides and Pallikarakis [20] investigates an

Potential geographic "hotspots" for drug-injection related transmission of HIV and HCV and for initiation into injecting drug use in New York City, 2011-2015, with implications for the current opioid epidemic in the US

PubMed Central

Cooper, H. L. F.; Arasteh, K.; Feelemyer, J.; McKnight, C.; Ross, Z.

2018-01-01

Objective We identified potential geographic “hotspots” for drug-injecting transmission of HIV and hepatitis C virus (HCV) among persons who inject drugs (PWID) in New York City. The HIV epidemic among PWID is currently in an “end of the epidemic” stage, while HCV is in a continuing, high prevalence (> 50%) stage. Methods We recruited 910 PWID entering Mount Sinai Beth Israel substance use treatment programs from 2011–2015. Structured interviews and HIV/ HCV testing were conducted. Residential ZIP codes were used as geographic units of analysis. Potential “hotspots” for HIV and HCV transmission were defined as 1) having relatively large numbers of PWID 2) having 2 or more HIV (or HCV) seropositive PWID reporting transmission risk—passing on used syringes to others, and 3) having 2 or more HIV (or HCV) seronegative PWID reporting acquisition risk—injecting with previously used needles/syringes. Hotspots for injecting drug use initiation were defined as ZIP codes with 5 or more persons who began injecting within the previous 6 years. Results Among PWID, 96% injected heroin, 81% male, 34% White, 15% African-American, 47% Latinx, mean age 40 (SD = 10), 7% HIV seropositive, 62% HCV seropositive. Participants resided in 234 ZIP codes. No ZIP codes were identified as potential hotspots due to small numbers of HIV seropositive PWID reporting transmission risk. Four ZIP codes were identified as potential hotspots for HCV transmission. 12 ZIP codes identified as hotspots for injecting drug use initiation. Discussion For HIV, the lack of potential hotspots is further validation of widespread effectiveness of efforts to reduce injecting-related HIV transmission. Injecting-related HIV transmission is likely to be a rare, random event. HCV prevention efforts should include focus on potential hotspots for transmission and on hotspots for initiation into injecting drug use. We consider application of methods for the current opioid epidemic in the US. PMID

Extended semen for artificial insemination in swine as a potential transmission mechanism for infectious Chlamydia suis.

PubMed

Hamonic, G; Pasternak, J A; Käser, T; Meurens, F; Wilson, H L

2016-09-01

Although typically unnoticed, Chlamydia infections in swine have been shown to be both widespread and may impact production characteristics and reproductive performance in swine. Serum titers suggest Chlamydia infection within boar studs is common, and infected boars are known to shed chlamydia in their ejaculates. Although the transmission of viruses in chilled extended semen (ES) is well established, the inclusion of antibiotics in commercially available extender is generally believed to limit or preclude the transmission of infectious bacteria. The objective of this study was to evaluate the potential of ES used in artificial insemination to support transmission of the obligate intracellular bacteria Chlamydia suis (C suis) under standard industry conditions. First, the effect of C suis on sperm quality during storage was assessed by flow cytometry. Only concentrations above 5 × 10(5) viable C suis/mL caused significant spermicidal effects which only became evident after 7 days of storage at 17 °C. No significant effect on acrosome reaction was observed using any chlamydial concentration. Next, an in vitro infection model of swine testicular fibroblast cells was established and used to evaluate the effect of chilled storage on C suis viability under variable conditions. Storage in Androhep ES reduced viability by 34.4% at a multiplicity of infection of 1.25, an effect which increased to 53.3% when the multiplicity of infection decreased to 0.1. Interestingly, storage in semen extender alone (SE) or ES with additional antibiotics had no effect on bacterial viability. To rule out a secondary effect on extender resulting from metabolically active sperm, C suis was stored in fresh and expended SE and again no significant effect on bacterial viability was observed. Fluorescent microscopy of C suis in ES shows an association between bacteria and the remaining gel fraction after storage suggesting that the apparent reduction of bacterial viability in the presence

Household transmission of SARS, 2003

PubMed Central

Wilson-Clark, Samantha D.; Deeks, Shelley L.; Gournis, Effie; Hay, Karen; Bondy, Susan; Kennedy, Erin; Johnson, Ian; Rea, Elizabeth; Kuschak, Theodore; Green, Diane; Abbas, Zahid; Guarda, Brenda

2006-01-01

Background In the 2003 outbreak in Toronto (in Ontario, Canada) of severe acute respiratory syndrome (SARS), about 20% of cases resulted from household transmission. The purpose of our study was to determine characteristics associated with the transmission of SARS within households. Methods A retrospective cohort of SARS-affected households was studied to determine risk factors for household transmission. Questionnaires addressed characteristics of the index case, the household and behaviours among household members. Potential risk factors for secondary transmission of infection were assessed in regression models appropriate to the outcome (secondary cases) and nonindependence of household members. Results The 74 households that participated included 18 secondary cases and 158 uninfected household members in addition to the 74 index cases. The household secondary attack rate was 10.2% (95% confidence interval [CI] 6.7%–23.5%). There was a linear association between the time the index patient spent at home after symptom onset and the secondary attack rate. Infected health care workers who were index cases had lower rates of household transmission. Interpretation SARS transmission in households is complex and increases with the length of time an ill person spends at home. Risk of transmission was lower when the index case was a health care worker. Rapid case identification is the public health measure most useful in minimizing exposure in the home. PMID:17098951

Pulse transmission transceiver architecture for low power communications

DOEpatents

Dress, Jr., William B.; Smith, Stephen F.

2003-08-05

Systems and methods for pulse-transmission low-power communication modes are disclosed. A method of pulse transmission communications includes: generating a modulated pulse signal waveform; transforming said modulated pulse signal waveform into at least one higher-order derivative waveform; and transmitting said at least one higher-order derivative waveform as an emitted pulse. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

Staff exchange within and between nursing homes in The Netherlands and potential implications for MRSA transmission.

PubMed

VAN Gaalen, R D; Hopman, H A; Haenen, A; VAN DEN Dool, C

2017-03-01

A recent countrywide MRSA spa-type 1081 outbreak in The Netherlands predominantly affected nursing homes, generating questions on how infection spreads within and between nursing homes despite a low national prevalence. Since the transfer of residents between nursing homes is uncommon in The Netherlands, we hypothesized that staff exchange plays an important role in transmission. This exploratory study investigated the extent of former (last 2 years) and current staff exchange within and between nursing homes in The Netherlands. We relied on a questionnaire that was targeted towards nursing-home staff members who had contact with residents. We found that 17·9% and 12·4% of the nursing-home staff formerly (last 2 years) or currently worked in other healthcare institutes besides their job in the nursing home through which they were selected to participate in this study. Moreover, 39·7% of study participants worked on more than one ward. Our study shows that, in The Netherlands, nursing-home staff form a substantial number of links between wards within nursing homes and nursing homes are linked to a large network of healthcare institutes through their staff members potentially providing a pathway for MRSA transmission between nursing homes and throughout the country.

Quantifying Transmission Investment in Malaria Parasites

PubMed Central

Greischar, Megan A.; Mideo, Nicole; Read, Andrew F.; Bjørnstad, Ottar N.

2016-01-01

Many microparasites infect new hosts with specialized life stages, requiring a subset of the parasite population to forgo proliferation and develop into transmission forms. Transmission stage production influences infectivity, host exploitation, and the impact of medical interventions like drug treatment. Predicting how parasites will respond to public health efforts on both epidemiological and evolutionary timescales requires understanding transmission strategies. These strategies can rarely be observed directly and must typically be inferred from infection dynamics. Using malaria as a case study, we test previously described methods for inferring transmission stage investment against simulated data generated with a model of within-host infection dynamics, where the true transmission investment is known. We show that existing methods are inadequate and potentially very misleading. The key difficulty lies in separating transmission stages produced by different generations of parasites. We develop a new approach that performs much better on simulated data. Applying this approach to real data from mice infected with a single Plasmodium chabaudi strain, we estimate that transmission investment varies from zero to 20%, with evidence for variable investment over time in some hosts, but not others. These patterns suggest that, even in experimental infections where host genetics and other environmental factors are controlled, parasites may exhibit remarkably different patterns of transmission investment. PMID:26890485

Weather Regulates Location, Timing, and Intensity of Dengue Virus Transmission between Humans and Mosquitoes

PubMed Central

Campbell, Karen M.; Haldeman, Kristin; Lehnig, Chris; Munayco, Cesar V.; Halsey, Eric S.; Laguna-Torres, V. Alberto; Yagui, Martín; Morrison, Amy C.; Lin, Chii-Dean; Scott, Thomas W.

2015-01-01

Background Dengue is one of the most aggressively expanding mosquito-transmitted viruses. The human burden approaches 400 million infections annually. Complex transmission dynamics pose challenges for predicting location, timing, and magnitude of risk; thus, models are needed to guide prevention strategies and policy development locally and globally. Weather regulates transmission-potential via its effects on vector dynamics. An important gap in understanding risk and roadblock in model development is an empirical perspective clarifying how weather impacts transmission in diverse ecological settings. We sought to determine if location, timing, and potential-intensity of transmission are systematically defined by weather. Methodology/Principal Findings We developed a high-resolution empirical profile of the local weather-disease connection across Peru, a country with considerable ecological diversity. Applying 2-dimensional weather-space that pairs temperature versus humidity, we mapped local transmission-potential in weather-space by week during 1994-2012. A binary classification-tree was developed to test whether weather data could classify 1828 Peruvian districts as positive/negative for transmission and into ranks of transmission-potential with respect to observed disease. We show that transmission-potential is regulated by temperature-humidity coupling, enabling epidemics in a limited area of weather-space. Duration within a specific temperature range defines transmission-potential that is amplified exponentially in higher humidity. Dengue-positive districts were identified by mean temperature >22°C for 7+ weeks and minimum temperature >14°C for 33+ weeks annually with 95% sensitivity and specificity. In elevated-risk locations, seasonal peak-incidence occurred when mean temperature was 26-29°C, coincident with humidity at its local maximum; highest incidence when humidity >80%. We profile transmission-potential in weather-space for temperature

Weather Regulates Location, Timing, and Intensity of Dengue Virus Transmission between Humans and Mosquitoes.

PubMed

Campbell, Karen M; Haldeman, Kristin; Lehnig, Chris; Munayco, Cesar V; Halsey, Eric S; Laguna-Torres, V Alberto; Yagui, Martín; Morrison, Amy C; Lin, Chii-Dean; Scott, Thomas W

2015-01-01

Dengue is one of the most aggressively expanding mosquito-transmitted viruses. The human burden approaches 400 million infections annually. Complex transmission dynamics pose challenges for predicting location, timing, and magnitude of risk; thus, models are needed to guide prevention strategies and policy development locally and globally. Weather regulates transmission-potential via its effects on vector dynamics. An important gap in understanding risk and roadblock in model development is an empirical perspective clarifying how weather impacts transmission in diverse ecological settings. We sought to determine if location, timing, and potential-intensity of transmission are systematically defined by weather. We developed a high-resolution empirical profile of the local weather-disease connection across Peru, a country with considerable ecological diversity. Applying 2-dimensional weather-space that pairs temperature versus humidity, we mapped local transmission-potential in weather-space by week during 1994-2012. A binary classification-tree was developed to test whether weather data could classify 1828 Peruvian districts as positive/negative for transmission and into ranks of transmission-potential with respect to observed disease. We show that transmission-potential is regulated by temperature-humidity coupling, enabling epidemics in a limited area of weather-space. Duration within a specific temperature range defines transmission-potential that is amplified exponentially in higher humidity. Dengue-positive districts were identified by mean temperature >22°C for 7+ weeks and minimum temperature >14°C for 33+ weeks annually with 95% sensitivity and specificity. In elevated-risk locations, seasonal peak-incidence occurred when mean temperature was 26-29°C, coincident with humidity at its local maximum; highest incidence when humidity >80%. We profile transmission-potential in weather-space for temperature-humidity ranging 0-38°C and 5-100% at 1°C x 2

Avian influenza virus transmission to mammals.

PubMed

Herfst, S; Imai, M; Kawaoka, Y; Fouchier, R A M

2014-01-01

Influenza A viruses cause yearly epidemics and occasional pandemics. In addition, zoonotic influenza A viruses sporadically infect humans and may cause severe respiratory disease and fatalities. Fortunately, most of these viruses do not have the ability to be efficiently spread among humans via aerosols or respiratory droplets (airborne transmission) and to subsequently cause a pandemic. However, adaptation of these zoonotic viruses to humans by mutation or reassortment with human influenza A viruses may result in airborne transmissible viruses with pandemic potential. Although our knowledge of factors that affect mammalian adaptation and transmissibility of influenza viruses is still limited, we are beginning to understand some of the biological traits that drive airborne transmission of influenza viruses among mammals. Increased understanding of the determinants and mechanisms of airborne transmission may aid in assessing the risks posed by avian influenza viruses to human health, and preparedness for such risks. This chapter summarizes recent discoveries on the genetic and phenotypic traits required for avian influenza viruses to become airborne transmissible between mammals.

Effects of flooding of the River Paraná on the temporal activity of Anopheles (Nyssorhynchus) darlingi Root (Diptera: Culicidae), at the border state of Mato Grosso do Sul and São Paulo, Brazil.

PubMed

Gomes, Almério de Castro; Paula, Marcia Bicudo de; Natal, Delsio; Gotlieb, Sabina Léa Davidson; Mucci, Luis Filipe

2010-01-01

Study of the temporal activity of malaria vectors during the implantation of a hydroelectric power station on the River Paraná, intended to generate electrical energy. The river separates the States of São Paulo and Mato Grosso do Sul, in Brazil. The objective was to verify whether alterations occurred in the wealth and diversity indices of Anopheles, following two successive floods, extended to the temporal activity and nycthemeral rhythm followed over a five year period. Mosquito capture was performed monthly using the Human Attraction Technique and Shannon Traps. The first, executed for 24h, provided the nycthemeral rhythm and the second, lasting 15 h, permitted the tracking of Anopheles during the two floods. The bimodal pattern of Anopheles darlingi defined before these floods was modified throughout the environment interventions. The same effect had repercussions on the populations of An albitarsis s.l., An triannulatus and An galvaoi. Activity prior to twilight was less affected by the environment alterations. The dam construction provoked changes in Anopheles temporal activity patterns, permitting classification of the area as an ecologically steady and unstable situation. Differences observed in Anopheles behavior due to the capture methods revealed the influence of solo and multiple attractiveness inside the populations studied.

Aerosol Transmission of Filoviruses

PubMed Central

Mekibib, Berhanu; Ariën, Kevin K.

2016-01-01

Filoviruses have become a worldwide public health concern because of their potential for introductions into non-endemic countries through international travel and the international transport of infected animals or animal products. Since it was first identified in 1976, in the Democratic Republic of Congo (formerly Zaire) and Sudan, the 2013–2015 western African Ebola virus disease (EVD) outbreak is the largest, both by number of cases and geographical extension, and deadliest, recorded so far in medical history. The source of ebolaviruses for human index case(s) in most outbreaks is presumptively associated with handling of bush meat or contact with fruit bats. Transmission among humans occurs easily when a person comes in contact with contaminated body fluids of patients, but our understanding of other transmission routes is still fragmentary. This review deals with the controversial issue of aerosol transmission of filoviruses. PMID:27223296

Larval habitats of Anopheles species in a rural settlement on the malaria frontier of southwest Amazon, Brazil.

PubMed

Rufalco-Moutinho, Paulo; Schweigmann, Nicolás; Bergamaschi, Denise Pimentel; Mureb Sallum, Maria Anice

2016-12-01

Rural settlements are social arrangements expanding in the Amazon region, which generate disturbances in the natural environment, thus affecting the ecology of the species of Anopheles and thus the malaria transmission. Larval habitats are important sources for maintenance of mosquito vector populations, and holding back a natural watercourse is a usual process in the establishment of rural settlements, since the formation of micro-dams represents a water resource for the new settlers. Identifying characteristics of the larval habitats that may be associated with both the presence and abundance of Anopheles vectors species in an environment under ecological transition is background for planning vector control strategies in rural areas in the Amazon. Anopheles larvae collections were performed in two major types of habitats: natural and flow-limited water collections that were constructed by holding back the original watercourse. A total of 3123 Anopheles spp. larvae were captured in three field-sampling collections. The majority of the larvae identified were taken from flow-limited water collections belonged to species of the Nyssorhynchus subgenus (92%), whereas in the natural larval habitats a fewer number of individuals belonged to the Stethomyia (5%) and Anopheles (3%) subgenera. The total of Nyssorhynchus identified (1818), 501 specimens belonged to An. darlingi, 750 to An. triannulatus and 567 for others remaining species. In addition, 1152 could not be identified to subgenus/species level, because they were either in the first-instar or damaged. The primary vector in areas of the Amazon river basin, An. darlingi, was found exclusively in man-made habitats. Statistical analysis display An. triannulatus with specialist behavior for characteristics of man-made habitats. Modifications in the natural environment facilitate the rise of larval habitats for species with epidemiological importance for malaria in the region. This study showed that man-made habitats

Preliminary Observations on the Changing Roles of Malaria Vectors in Southern Belize

DTIC Science & Technology

1993-01-01

darlingi (Diptera: Cu- licidae) de la Ceiba, Atlantida, Honduras. Thesis. Maestria en Entomologia. Universidad de Panama, Panama City, Panama. 456...Brown and C. Cordon-Rosales. 1992. Potential malaria vectors in northern Guatemala (Vectores potenciales de ma- laria in la region norte de Guatemala...Serra de Aqua in June 1946 (Linthicum 1988). We initiated a malaria vector research pro- gram in Belize in 1990 and conducted extensive larval

Space-to-earth power transmission system

NASA Technical Reports Server (NTRS)

Stevens, G. H.; Schuh, R.

1976-01-01

A preliminary analysis was conducted to establish the requirements of a space-to-earth microwave power transmission system. The need for accurate phase control on the transmitter was established and methods for assessing the impact of power density and thermal constraints on system performance were demonstrated. Potential radio frequency interference was considered. The sensitivity of transmission system scale to variations in power source, transportation and orbital fabrication and assembly costs was also determined.

Predators and patterns of within-host growth can mediate both among-host competition and evolution of transmission potential of parasites.

PubMed

Auld, Stuart K J R; Hall, Spencer R; Housley Ochs, Jessica; Sebastian, Mathew; Duffy, Meghan A

2014-08-01

Parasite prevalence shows tremendous spatiotemporal variation. Theory indicates that this variation might stem from life-history characteristics of parasites and key ecological factors. Here, we illustrate how the interaction of an important predator and the schedule of transmission potential of two parasites can explain parasite abundance. A field survey showed that a noncastrating fungus (Metschnikowia bicuspidata) commonly infected a dominant zooplankton host (Daphnia dentifera), while a castrating bacterial parasite (Pasteuria ramosa) was rare. This result seemed surprising given that the bacterium produces many more infectious propagules (spores) than the fungus upon host death. The fungus's dominance can be explained by the schedule of within-host growth of parasites (i.e., how transmission potential changes over the course of infection) and the release of spores from "sloppy" predators (Chaoborus spp., who consume Daphnia prey whole and then later regurgitate the carapace and parasite spores). In essence, sloppy predators create a niche that the faster-schedule fungus currently occupies. However, a selection experiment showed that the slower-schedule bacterium can evolve into this faster-schedule, predator-mediated niche (but pays a cost in maximal spore yield to do so). Hence, our study shows how parasite life history can interact with predation to strongly influence the ecology, epidemiology, and evolution of infectious disease.

The potential for flower nectar to allow mosquito to mosquito transmission of Francisella tularensis.

PubMed

Kenney, Adam; Cusick, Austin; Payne, Jessica; Gaughenbaugh, Anna; Renshaw, Andrea; Wright, Jenna; Seeber, Roger; Barnes, Rebecca; Florjanczyk, Aleksandr; Horzempa, Joseph

2017-01-01

Francisella tularensis is disseminated in nature by biting arthropods such as mosquitoes. The relationship between mosquitoes and F. tularensis in nature is highly ambiguous, due in part to the fact that mosquitoes have caused significant tularemia outbreaks despite being classified as a mechanical vector of F. tularensis. One possible explanation for mosquitoes being a prominent, yet mechanical vector is that these insects feed on flower nectar between blood meals, allowing for transmission of F. tularensis between mosquitoes. Here, we aimed to assess whether F. tularensis could survive in flower nectar. Moreover, we examined if mosquitoes could interact with or ingest and transmit F. tularensis from one source of nectar to another. F. tularensis exhibited robust survivability in flower nectar with concentrations of viable bacteria remaining consistent with the rich growth medium. Furthermore, F. tularensis was able to survive (albeit to a lesser extent) in 30% sucrose (a nectar surrogate) over a period of time consistent with that of a typical flower bloom. Although we observed diminished bacterial survival in the nectar surrogate, mosquitoes that fed on this material became colonized with F. tularensis. Finally, colonized mosquitoes were capable of transferring F. tularensis to a sterile nectar surrogate. These data suggest that flower nectar may be capable of serving as a temporary source of F. tularensis that could contribute to the amplification of outbreaks. Mosquitoes that feed on an infected mammalian host and subsequently feed on flower nectar could deposit some F. tularensis bacteria into the nectar in the process. Mosquitoes subsequently feeding on this nectar source could potentially become colonized by F. tularensis. Thus, the possibility exists that flower nectar may allow for vector-vector transmission of F. tularensis.

Distribution of the Habitat Suitability of the Main Malaria Vector in French Guiana Using Maximum Entropy Modeling.

PubMed

Moua, Yi; Roux, Emmanuel; Girod, Romain; Dusfour, Isabelle; de Thoisy, Benoit; Seyler, Frédérique; Briolant, Sébastien

2017-05-01

Malaria is an important health issue in French Guiana. Its principal mosquito vector in this region is Anopheles darlingi Root. Knowledge of the spatial distribution of this species is still very incomplete due to the extent of French Guiana and the difficulty to access most of the territory. Species distribution modeling based on the maximal entropy procedure was used to predict the spatial distribution of An. darlingi using 39 presence sites. The resulting model provided significantly high prediction performances (mean 10-fold cross-validated partial area under the curve and continuous Boyce index equal to, respectively, 1.11-with a level of omission error of 20%-and 0.42). The model also provided a habitat suitability map and environmental response curves in accordance with the known entomological situation. Several environmental characteristics that had a positive correlation with the presence of An. darlingi were highlighted: nonpermanent anthropogenic changes of the natural environment, the presence of roads and tracks, and opening of the forest. Some geomorphological landforms and high altitude landscapes appear to be unsuitable for An. darlingi. The species distribution modeling was able to reliably predict the distribution of suitable habitats for An. darlingi in French Guiana. Results allowed completion of the knowledge of the spatial distribution of the principal malaria vector in this Amazonian region, and identification of the main factors that favor its presence. They should contribute to the definition of a necessary targeted vector control strategy in a malaria pre-elimination stage, and allow extrapolation of the acquired knowledge to other Amazonian or malaria-endemic contexts. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Cross-species transmission potential between wild pigs, livestock, poultry, wildlife, and humans: Implications for disease risk management in North America

USGS Publications Warehouse

Miller, Ryan S.; Sweeney, Steven J.; Slootmaker, Chris; Grear, Daniel A.; DiSalvo, Paul A.; Kiser, Deborah; Shwiff, Stephanie A.

2017-01-01

Cross-species disease transmission between wildlife, domestic animals and humans is an increasing threat to public and veterinary health. Wild pigs are increasingly a potential veterinary and public health threat. Here we investigate 84 pathogens and the host species most at risk for transmission with wild pigs using a network approach. We assess the risk to agricultural and human health by evaluating the status of these pathogens and the co-occurrence of wild pigs, agriculture and humans. We identified 34 (87%) OIE listed swine pathogens that cause clinical disease in livestock, poultry, wildlife, and humans. On average 73% of bacterial, 39% of viral, and 63% of parasitic pathogens caused clinical disease in other species. Non-porcine livestock in the family Bovidae shared the most pathogens with swine (82%). Only 49% of currently listed OIE domestic swine diseases had published wild pig surveillance studies. The co-occurrence of wild pigs and farms increased annually at a rate of 1.2% with as much as 57% of all farms and 77% of all agricultural animals co-occurring with wild pigs. The increasing co-occurrence of wild pigs with livestock and humans along with the large number of pathogens shared is a growing risk for cross-species transmission.

Cross-species transmission potential between wild pigs, livestock, poultry, wildlife, and humans: implications for disease risk management in North America.

PubMed

Miller, Ryan S; Sweeney, Steven J; Slootmaker, Chris; Grear, Daniel A; Di Salvo, Paul A; Kiser, Deborah; Shwiff, Stephanie A

2017-08-10

Cross-species disease transmission between wildlife, domestic animals and humans is an increasing threat to public and veterinary health. Wild pigs are increasingly a potential veterinary and public health threat. Here we investigate 84 pathogens and the host species most at risk for transmission with wild pigs using a network approach. We assess the risk to agricultural and human health by evaluating the status of these pathogens and the co-occurrence of wild pigs, agriculture and humans. We identified 34 (87%) OIE listed swine pathogens that cause clinical disease in livestock, poultry, wildlife, and humans. On average 73% of bacterial, 39% of viral, and 63% of parasitic pathogens caused clinical disease in other species. Non-porcine livestock in the family Bovidae shared the most pathogens with swine (82%). Only 49% of currently listed OIE domestic swine diseases had published wild pig surveillance studies. The co-occurrence of wild pigs and farms increased annually at a rate of 1.2% with as much as 57% of all farms and 77% of all agricultural animals co-occurring with wild pigs. The increasing co-occurrence of wild pigs with livestock and humans along with the large number of pathogens shared is a growing risk for cross-species transmission.

Influenza A virus transmission via respiratory aerosols or droplets as it relates to pandemic potential

PubMed Central

Richard, Mathilde; Fouchier, Ron A.M.

2015-01-01

Many respiratory viruses of humans originate from animals. For instance, there are now eight paramyxoviruses, four coronaviruses and four orthomxoviruses that cause recurrent epidemics in humans but were once confined to other hosts. In the last decade, several members of the same virus families have jumped the species barrier from animals to humans. Fortunately, these viruses have not become established in humans, because they lacked the ability of sustained transmission between humans. However, these outbreaks highlighted the lack of understanding of what makes a virus transmissible. In part triggered by the relatively high frequency of occurrence of influenza A virus zoonoses and pandemics, the influenza research community has started to investigate the viral genetic and biological traits that drive virus transmission via aerosols or respiratory droplets between mammals. Here we summarize recent discoveries on the genetic and phenotypic traits required for airborne transmission of zoonotic influenza viruses of subtypes H5, H7 and H9 and pandemic viruses of subtypes H1, H2 and H3. Increased understanding of the determinants and mechanisms of respiratory virus transmission is not only key from a basic scientific perspective, but may also aid in assessing the risks posed by zoonotic viruses to human health, and preparedness for such risks. PMID:26385895

Adaptation and evaluation of the bottle assay for monitoring insecticide resistance in disease vector mosquitoes in the Peruvian Amazon

PubMed Central

Zamora Perea, Elvira; Balta León, Rosario; Palomino Salcedo, Miriam; Brogdon, William G; Devine, Gregor J

2009-01-01

Background The purpose of this study was to establish whether the "bottle assay", a tool for monitoring insecticide resistance in mosquitoes, can complement and augment the capabilities of the established WHO assay, particularly in resource-poor, logistically challenging environments. Methods Laboratory reared Aedes aegypti and field collected Anopheles darlingi and Anopheles albimanus were used to assess the suitability of locally sourced solvents and formulated insecticides for use with the bottle assay. Using these adapted protocols, the ability of the bottle assay and the WHO assay to discriminate between deltamethrin-resistant Anopheles albimanus populations was compared. The diagnostic dose of deltamethrin that would identify resistance in currently susceptible populations of An. darlingi and Ae. aegypti was defined. The robustness of the bottle assay during a surveillance exercise in the Amazon was assessed. Results The bottle assay (using technical or formulated material) and the WHO assay were equally able to differentiate deltamethrin-resistant and susceptible An. albimanus populations. A diagnostic dose of 10 μg a.i./bottle was identified as the most sensitive discriminating dose for characterizing resistance in An. darlingi and Ae. aegypti. Treated bottles, prepared using locally sourced solvents and insecticide formulations, can be stored for > 14 days and used three times. Bottles can be stored and transported under local conditions and field-assays can be completed in a single evening. Conclusion The flexible and portable nature of the bottle assay and the ready availability of its components make it a potentially robust and useful tool for monitoring insecticide resistance and efficacy in remote areas that require minimal cost tools. PMID:19728871

When More Transmission Equals Less Disease: Reconciling the Disconnect between Disease Hotspots and Parasite Transmission

PubMed Central

Park, Andrew W.; Magori, Krisztian; White, Brad A.; Stallknecht, David E.

2013-01-01

The assumed straightforward connection between transmission intensity and disease occurrence impacts surveillance and control efforts along with statistical methodology, including parameter inference and niche modeling. Many infectious disease systems have the potential for this connection to be more complicated–although demonstrating this in any given disease system has remained elusive. Hemorrhagic disease (HD) is one of the most important diseases of white-tailed deer and is caused by viruses in the Orbivirus genus. Like many infectious diseases, the probability or severity of disease increases with age (after loss of maternal antibodies) and the probability of disease is lower upon re-infection compared to first infection (based on cross-immunity between virus strains). These broad criteria generate a prediction that disease occurrence is maximized at intermediate levels of transmission intensity. Using published US field data, we first fit a statistical model to predict disease occurrence as a function of seroprevalence (a proxy for transmission intensity), demonstrating that states with intermediate seroprevalence have the highest level of case reporting. We subsequently introduce an independently parameterized mechanistic model supporting the theory that high case reporting should come from areas with intermediate levels of transmission. This is the first rigorous demonstration of this phenomenon and illustrates that variation in transmission rate (e.g. along an ecologically-controlled transmission gradient) can create cryptic refuges for infectious diseases. PMID:23579922

Loofah sponges as reservoirs and vehicles in the transmission of potentially pathogenic bacterial species to human skin.

PubMed Central

Bottone, E J; Perez, A A; Oeser, J L

1994-01-01

Loofah sponges are natural products used as exfoliative beauty aids. As a consequence of tracing a case of Pseudomonas aeruginosa folliculitis to a contaminated loofah sponge, we assessed the role of loofah sponges in supporting the growth of a wide variety of bacterial species. Our data show growth enhancement of sterile loofah fragments for numerous gram-negative (Pseudomonas, Xanthomonas, and Klebsiella) and gram-positive (Enterococcus and group B Streptococcus) species of human and environmental origin. Furthermore, hydrated new, unused loofah sponges undergo a shift in bacterial flora from sparse colonies of Bacillus spp. and Staphylococcus epidermidis to a predominantly gram-negative flora. The growth-promoting potential of loofah sponges (and other exfoliatives) can be further augmented by desquamated epithelial cells entrapped in the loofah fibrous matrix. Therefore, as loofah sponges (and other exfoliatives) can serve as a reservoir and a vehicle for the transmission of potentially pathogenic species to the human skin, we recommend their decontamination with hypochlorite (10%) bleach at regular intervals. Images PMID:8150959

Loofah sponges as reservoirs and vehicles in the transmission of potentially pathogenic bacterial species to human skin.

PubMed

Bottone, E J; Perez, A A; Oeser, J L

1994-02-01

Loofah sponges are natural products used as exfoliative beauty aids. As a consequence of tracing a case of Pseudomonas aeruginosa folliculitis to a contaminated loofah sponge, we assessed the role of loofah sponges in supporting the growth of a wide variety of bacterial species. Our data show growth enhancement of sterile loofah fragments for numerous gram-negative (Pseudomonas, Xanthomonas, and Klebsiella) and gram-positive (Enterococcus and group B Streptococcus) species of human and environmental origin. Furthermore, hydrated new, unused loofah sponges undergo a shift in bacterial flora from sparse colonies of Bacillus spp. and Staphylococcus epidermidis to a predominantly gram-negative flora. The growth-promoting potential of loofah sponges (and other exfoliatives) can be further augmented by desquamated epithelial cells entrapped in the loofah fibrous matrix. Therefore, as loofah sponges (and other exfoliatives) can serve as a reservoir and a vehicle for the transmission of potentially pathogenic species to the human skin, we recommend their decontamination with hypochlorite (10%) bleach at regular intervals.

Experimental Transmission of Mayaro Virus by Aedes aegypti

PubMed Central

Long, Kanya C.; Ziegler, Sarah A.; Thangamani, Saravanan; Hausser, Nicole L.; Kochel, Tadeusz J.; Higgs, Stephen; Tesh, Robert B.

2011-01-01

Outbreaks of Mayaro fever have been associated with a sylvatic cycle of Mayaro virus (MAYV) transmission in South America. To evaluate the potential for a common urban mosquito to transmit MAYV, laboratory vector competence studies were performed with Aedes aegypti from Iquitos, Peru. Oral infection in Ae. aegypti ranged from 0% (0/31) to 84% (31/37), with blood meal virus titers between 3.4 log10 and 7.3 log10 plaque-forming units (PFU)/mL. Transmission of MAYV by 70% (21/30) of infected mosquitoes was shown by saliva collection and exposure to suckling mice. Amount of viral RNA in febrile humans, determined by real-time polymerase chain reaction, ranged from 2.7 to 5.3 log10 PFU equivalents/mL. Oral susceptibility of Ae. aegypti to MAYV at titers encountered in viremic humans may limit opportunities to initiate an urban cycle; however, transmission of MAYV by Ae. aegypti shows the vector competence of this species and suggests potential for urban transmission. PMID:21976583

Social place as a location of potential core transmitters-implications for the targeted control of sexually transmitted disease transmission in urban areas.

PubMed

Jennings, Jacky M; Polk, Sarah; Fichtenberg, Caroline; Chung, Shang-en; Ellen, Jonathan M

2015-11-01

Places are an important determinant of risk for sexually transmitted infection (STI) acquisition and transmission. We sought to identify social places that are critical for targeted STI control activities. The objective of this study was to determine whether sex partner meeting places characterized by drug markets, sex markets, and separately, drug and/or sex markets were more likely to have potential core transmitters as compared with other sex partner meeting places in one urban setting. In 2008-2009, heterosexual sex partner places or venues were identified in Baltimore, MD using a venue-based study approach. A total of 1334 participants aged 18 to 35 years were enrolled at 85 venues. In those participants, 39 potential core transmitters were identified and 31% of venues had at least one potential core transmitter. In final age-adjusted and gender-adjusted models, core transmitters were significantly more likely to be identified at drug markets (OR = 1.37; 95% CI = 1.23-1.53), sex markets (OR = 1.27; 95% CI = 1.14-1.41), and drug and/or sex markets (OR = 1.49; 95% CI = 1.32-1.68). This study identified key characteristics of venues, such as drug and sex market activity, that may be important in identifying places for the targeted control of STI transmission. Copyright © 2015 Elsevier Inc. All rights reserved.

Controllable asymmetric transmission via gap-tunable acoustic metasurface

NASA Astrophysics Data System (ADS)

Liu, Bingyi; Jiang, Yongyuan

2018-04-01

In this work, we utilize the acoustic gradient metasurface (AGM) of a bilayer configuration to realize the controllable asymmetric transmission. Relying on the adjustable gap between the two composing layers, the metasurface could switch from symmetric transmission to asymmetric transmission at a certain gap value. The underlying mechanism is attributed to the interference between the forward diffracted waves scattered by the surface bound waves at two air-AGM interfaces, which is apparently influenced by the interlayer distance. We further utilize the hybrid acoustic elements to construct the desired gradient metasurface with a tunable gap and validate the controllable asymmetric transmission with full-wave simulations. Our work provides the solution for actively controlling the transmission property of an acoustic element, which shows potential application in acoustic communication as a dynamic tunable acoustic diode.

The potential for flower nectar to allow mosquito to mosquito transmission of Francisella tularensis

PubMed Central

Payne, Jessica; Gaughenbaugh, Anna; Renshaw, Andrea; Wright, Jenna; Seeber, Roger; Barnes, Rebecca; Florjanczyk, Aleksandr; Horzempa, Joseph

2017-01-01

Francisella tularensis is disseminated in nature by biting arthropods such as mosquitoes. The relationship between mosquitoes and F. tularensis in nature is highly ambiguous, due in part to the fact that mosquitoes have caused significant tularemia outbreaks despite being classified as a mechanical vector of F. tularensis. One possible explanation for mosquitoes being a prominent, yet mechanical vector is that these insects feed on flower nectar between blood meals, allowing for transmission of F. tularensis between mosquitoes. Here, we aimed to assess whether F. tularensis could survive in flower nectar. Moreover, we examined if mosquitoes could interact with or ingest and transmit F. tularensis from one source of nectar to another. F. tularensis exhibited robust survivability in flower nectar with concentrations of viable bacteria remaining consistent with the rich growth medium. Furthermore, F. tularensis was able to survive (albeit to a lesser extent) in 30% sucrose (a nectar surrogate) over a period of time consistent with that of a typical flower bloom. Although we observed diminished bacterial survival in the nectar surrogate, mosquitoes that fed on this material became colonized with F. tularensis. Finally, colonized mosquitoes were capable of transferring F. tularensis to a sterile nectar surrogate. These data suggest that flower nectar may be capable of serving as a temporary source of F. tularensis that could contribute to the amplification of outbreaks. Mosquitoes that feed on an infected mammalian host and subsequently feed on flower nectar could deposit some F. tularensis bacteria into the nectar in the process. Mosquitoes subsequently feeding on this nectar source could potentially become colonized by F. tularensis. Thus, the possibility exists that flower nectar may allow for vector-vector transmission of F. tularensis. PMID:28486521

Echinococcosis: disease, detection and transmission.

PubMed

Craig, P S; Rogan, M T; Campos-Ponce, M

2003-01-01

Echinococcosis is one of the world's most geographically widespread parasitic zoonoses, with transmission occurring in tropical, temperate and arctic biomes. Most human infections are due to Echinococcus granulosus transmitted between domestic dogs and livestock, but this cosmopolitan species also cycles between wild carnivores (principally canids) and wild ungulates. The other species with significant zoonotic potential is E. multilocularis that occurs naturally in fox definitive hosts and small mammal intermediate hosts. These two species cause human cystic or alveolar echinococcosis respectively, which may be considered serious public health problems in several regions including developed countries. This review provides an introductory overview to the Supplement and summarises the biology and epidemiology of these two related cestodes with an emphasis on applied aspects relating to detection, diagnosis and surveillance in animal and human populations, and includes aspects of transmission ecology, and also considers aspects of community epidemiology and potential for control.

Airborne transmission of respiratory diseases.

PubMed

Baker, S A

1995-01-01

In surveys during the past decade, CEs and BMETs have reported an increasing frequency of respiratory illnesses they believed to be acquired as a result of their occupation. These illnesses varied from mild to severe in terms of long-term prognosis. With the increasing numbers of cases of drug-resistant organisms, respiratory infections are a growing concern for healthcare workers, employers, and government officials. Armed with a better knowledge base about symptoms, transmission and prevention, CEs and BMETs will be more aware of potential biohazardous situations and the necessary personal protective measures to be employed. Both the Occupational Safety and Health Administration (OSHA) and the Centers for Disease Control and Prevention (CDCP) have issued guidelines for preventing airborne transmission of infectious diseases. This paper addresses the respiratory illnesses reported by CEs and BMETs as occupational concerns, as well as briefly discussing potential epidemic pulmonary conditions.

Seasonal forecast of St. Louis encephalitis virus transmission, Florida.

PubMed

Shaman, Jeffrey; Day, Jonathan F; Stieglitz, Marc; Zebiak, Stephen; Cane, Mark

2004-05-01

Disease transmission forecasts can help minimize human and domestic animal health risks by indicating where disease control and prevention efforts should be focused. For disease systems in which weather-related variables affect pathogen proliferation, dispersal, or transmission, the potential for disease forecasting exists. We present a seasonal forecast of St. Louis encephalitis virus transmission in Indian River County, Florida. We derive an empiric relationship between modeled land surface wetness and levels of SLEV transmission in humans. We then use these data to forecast SLEV transmission with a seasonal lead. Forecast skill is demonstrated, and a real-time seasonal forecast of epidemic SLEV transmission is presented. This study demonstrates how weather and climate forecast skill-verification analyses may be applied to test the predictability of an empiric disease forecast model.

Seasonal Forecast of St. Louis Encephalitis Virus Transmission, Florida

PubMed Central

Day, Jonathan F.; Stieglitz, Marc; Zebiak, Stephen; Cane, Mark

2004-01-01

Disease transmission forecasts can help minimize human and domestic animal health risks by indicating where disease control and prevention efforts should be focused. For disease systems in which weather-related variables affect pathogen proliferation, dispersal, or transmission, the potential for disease forecasting exists. We present a seasonal forecast of St. Louis encephalitis virus transmission in Indian River County, Florida. We derive an empirical relationship between modeled land surface wetness and levels of SLEV transmission in humans. We then use these data to forecast SLEV transmission with a seasonal lead. Forecast skill is demonstrated, and a real-time seasonal forecast of epidemic SLEV transmission is presented. This study demonstrates how weather and climate forecast skill verification analyses may be applied to test the predictability of an empirical disease forecast model. PMID:15200812

Storage, transmission and distribution of hydrogen

NASA Technical Reports Server (NTRS)

Kelley, J. H.; Hagler, R., Jr.

1979-01-01

Current practices and future requirements for the storage, transmission and distribution of hydrogen are reviewed in order to identify inadequacies to be corrected before hydrogen can achieve its full potential as a substitute for fossil fuels. Consideration is given to the storage of hydrogen in underground solution-mined salt caverns, portable high-pressure containers and dewars, pressure vessels and aquifers and as metal hydrides, hydrogen transmission in evacuated double-walled insulated containers and by pipeline, and distribution by truck and internal distribution networks. Areas for the improvement of these techniques are indicated, and these technological deficiencies, including materials development, low-cost storage and transmission methods, low-cost, long-life metal hydrides and novel methods for hydrogen storage, are presented as challenges for research and development.

Bovine coronavirus in naturally and experimentally exposed calves; viral shedding and the potential for transmission.

PubMed

Oma, Veslemøy Sunniva; Tråvén, Madeleine; Alenius, Stefan; Myrmel, Mette; Stokstad, Maria

2016-06-13

Bovine coronavirus (BCoV) is a widely distributed pathogen, causing disease and economic losses in the cattle industry worldwide. Prevention of virus spread is impeded by a lack of basic knowledge concerning viral shedding and transmission potential in individual animals. The aims of the study were to investigate the duration and quantity of BCoV shedding in feces and nasal secretions related to clinical signs, the presence of virus in blood and tissues and to test the hypothesis that seropositive calves are not infectious to naïve in-contact calves three weeks after BCoV infection. A live animal experiment was conducted, with direct contact between animal groups for 24 h as challenge procedure. Four naïve calves were commingled with a group of six naturally infected calves and sequentially euthanized. Two naïve sentinel calves were commingled with the experimentally exposed group three weeks after exposure. Nasal swabs, feces, blood and tissue samples were analyzed for viral RNA by RT-qPCR, and virus isolation was performed on nasal swabs. Serum was analyzed for BCoV antibodies. The calves showed mild general signs, and the most prominent signs were from the respiratory system. The overall clinical score corresponded well with the shedding of viral RNA the first three weeks after challenge. General depression and cough were the signs that correlated best with shedding of BCoV RNA, while peak respiratory rate and peak rectal temperature appeared more than a week later than the peak shedding. Nasal shedding preceded fecal shedding, and the calves had detectable amounts of viral RNA intermittently in feces through day 35 and in nasal secretions through day 28, however virus isolation was unsuccessful from day six and day 18 from the two calves investigated. Viral RNA was not detected in blood, but was found in lymphatic tissue through day 42 after challenge. Although the calves were shedding BCoV RNA 21 days after infection the sentinel animals were not infected

Operating a transmission company under open access: The basic requirements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunt, S.; Shuttleworth, G.

1993-03-01

In both Europe and North America, technical and legal changes are increasing the opportunities for electricity traders to use transmission lines and grids that are owned by other companies. This article discusses the view that transmission maybe a service potentially separable from the production and retailing of electricity, and that transmission should be freely available at an appropriate price. Grid operators are wary of proposals to open access to transmission. European legislators want grid operators to become Transmission System Operators (TSO), moving energy around the network for others. Also discussed in this article are the powers that the TSO shouldmore » be allowed to exercise if access to transmission is made available.« less

Geo-environmental model for the prediction of potential transmission risk of Dirofilaria in an area with dry climate and extensive irrigated crops. The case of Spain.

PubMed

Simón, Luis; Afonin, Alexandr; López-Díez, Lucía Isabel; González-Miguel, Javier; Morchón, Rodrigo; Carretón, Elena; Montoya-Alonso, José Alberto; Kartashev, Vladimir; Simón, Fernando

2014-03-01

Zoonotic filarioses caused by Dirofilaria immitis and Dirofilaria repens are transmitted by culicid mosquitoes. Therefore Dirofilaria transmission depends on climatic factors like temperature and humidity. In spite of the dry climate of most of the Spanish territory, there are extensive irrigated crops areas providing moist habitats favourable for mosquito breeding. A GIS model to predict the risk of Dirofilaria transmission in Spain, based on temperatures and rainfall data as well as in the distribution of irrigated crops areas, is constructed. The model predicts that potential risk of Dirofilaria transmission exists in all the Spanish territory. Highest transmission risk exists in several areas of Andalucía, Extremadura, Castilla-La Mancha, Murcia, Valencia, Aragón and Cataluña, where moderate/high temperatures coincide with extensive irrigated crops. High risk in Balearic Islands and in some points of Canary Islands, is also predicted. The lowest risk is predicted in Northern cold and scarcely or non-irrigated dry Southeastern areas. The existence of irrigations locally increases transmission risk in low rainfall areas of the Spanish territory. The model can contribute to implement rational preventive therapy guidelines in accordance with the transmission characteristics of each local area. Moreover, the use of humidity-related factors could be of interest in future predictions to be performed in countries with similar environmental characteristics. Copyright © 2014 Elsevier B.V. All rights reserved.

What We Know About Tuberculosis Transmission: An Overview.

PubMed

Churchyard, Gavin; Kim, Peter; Shah, N Sarita; Rustomjee, Roxana; Gandhi, Neel; Mathema, Barun; Dowdy, David; Kasmar, Anne; Cardenas, Vicky

2017-11-03

Tuberculosis remains a global health problem with an enormous burden of disease, estimated at 10.4 million new cases in 2015. To stop the tuberculosis epidemic, it is critical that we interrupt tuberculosis transmission. Further, the interventions required to interrupt tuberculosis transmission must be targeted to high-risk groups and settings. A simple cascade for tuberculosis transmission has been proposed in which (1) a source case of tuberculosis (2) generates infectious particles (3) that survive in the air and (4) are inhaled by a susceptible individual (5) who may become infected and (6) then has the potential to develop tuberculosis. Interventions that target these events will interrupt tuberculosis transmission and accelerate the decline in tuberculosis incidence and mortality. The purpose of this article is to provide a high-level overview of what is known about tuberculosis transmission, using the tuberculosis transmission cascade as a framework, and to set the scene for the articles in this series, which address specific aspects of tuberculosis transmission. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Zoonotic Transmission of Waterborne Disease: A Mathematical Model.

PubMed

Waters, Edward K; Hamilton, Andrew J; Sidhu, Harvinder S; Sidhu, Leesa A; Dunbar, Michelle

2016-01-01

Waterborne parasites that infect both humans and animals are common causes of diarrhoeal illness, but the relative importance of transmission between humans and animals and vice versa remains poorly understood. Transmission of infection from animals to humans via environmental reservoirs, such as water sources, has attracted attention as a potential source of endemic and epidemic infections, but existing mathematical models of waterborne disease transmission have limitations for studying this phenomenon, as they only consider contamination of environmental reservoirs by humans. This paper develops a mathematical model that represents the transmission of waterborne parasites within and between both animal and human populations. It also improves upon existing models by including animal contamination of water sources explicitly. Linear stability analysis and simulation results, using realistic parameter values to describe Giardia transmission in rural Australia, show that endemic infection of an animal host with zoonotic protozoa can result in endemic infection in human hosts, even in the absence of person-to-person transmission. These results imply that zoonotic transmission via environmental reservoirs is important.

Early warnings of the potential for malaria transmission in Rural Africa using the Hydrology, Entomology and Malaria Transmission Simulator (HYDREMATS)

NASA Astrophysics Data System (ADS)

Yamana, T. K.; Eltahir, E. A.

2010-12-01

Early warnings of malaria transmission allow health officials to better prepare for future epidemics. Monitoring rainfall is recognized as an important part of malaria early warning systems, as outlined by the Roll Back Malaria Initiative. The Hydrology, Entomology and Malaria Simulator (HYDREMATS) is a mechanistic model that relates rainfall to malaria transmission, and could be used to provide early warnings of malaria epidemics. HYDREMATS is used to make predictions of mosquito populations and vectorial capacity for 2005, 2006, and 2007 in Banizoumbou village in western Niger. HYDREMATS is forced by observed rainfall, followed by a rainfall prediction based on the seasonal mean rainfall for a period two or four weeks into the future. Predictions made using this method provided reasonable estimates of mosquito populations and vectorial capacity, two to four weeks in advance. The predictions were significantly improved compared to those made when HYDREMATS was forced with seasonal mean rainfall alone.

Quantifying the relative effects of environmental and direct transmission of norovirus

PubMed Central

Chen, J.; Cruz, C.; Melendez, J.; Rodriguez, J.; Salinas, A.; Yu, F.; Kang, Y.

2018-01-01

Norovirus is a common cause of outbreaks of acute gastroenteritis in health- and child-care settings, with serial outbreaks also frequently observed aboard cruise ships. The relative contributions of environmental and direct person-to-person transmission of norovirus have hitherto not been quantified. We employ a novel mathematical model of norovirus transmission, and fit the model to daily incidence data from a major norovirus outbreak on a cruise ship, and examine the relative efficacy of potential control strategies aimed at reducing environmental and/or direct transmission. The reproduction number for environmental and direct transmission combined is R0tot=7.2 [6.1,9.5], and of environmental transmission alone is R0environ=1.6 [0.9,2.6]. Direct transmission is overwhelmingly due to passenger-to-passenger contacts, but crew can act as a reservoir of infection from cruise to cruise. This is the first quantification of the relative roles of environmental and direct transmission of norovirus. While environmental transmission has the potential to maintain a sustained series of outbreaks aboard a cruise ship in the absence of strict sanitation practices, direct transmission dominates. We find that intensive promotion of good hand washing practices may prevent outbreaks. Isolation of ill passengers and cleaning are beneficial, but appear to be less efficacious at outbreak control. PMID:29657742

Climate and dengue transmission: evidence and implications.

PubMed

Morin, Cory W; Comrie, Andrew C; Ernst, Kacey

2013-01-01

Climate influences dengue ecology by affecting vector dynamics, agent development, and mosquito/human interactions. Although these relationships are known, the impact climate change will have on transmission is unclear. Climate-driven statistical and process-based models are being used to refine our knowledge of these relationships and predict the effects of projected climate change on dengue fever occurrence, but results have been inconsistent. We sought to identify major climatic influences on dengue virus ecology and to evaluate the ability of climate-based dengue models to describe associations between climate and dengue, simulate outbreaks, and project the impacts of climate change. We reviewed the evidence for direct and indirect relationships between climate and dengue generated from laboratory studies, field studies, and statistical analyses of associations between vectors, dengue fever incidence, and climate conditions. We assessed the potential contribution of climate-driven, process-based dengue models and provide suggestions to improve their performance. Relationships between climate variables and factors that influence dengue transmission are complex. A climate variable may increase dengue transmission potential through one aspect of the system while simultaneously decreasing transmission potential through another. This complexity may at least partly explain inconsistencies in statistical associations between dengue and climate. Process-based models can account for the complex dynamics but often omit important aspects of dengue ecology, notably virus development and host-species interactions. Synthesizing and applying current knowledge of climatic effects on all aspects of dengue virus ecology will help direct future research and enable better projections of climate change effects on dengue incidence.

Human-armadillo interaction in Ceará, Brazil: Potential for transmission of Mycobacterium leprae.

PubMed

Kerr, Ligia; Kendall, Carl; Sousa, Cesar Augusto Barros de; Frota, Cristiane Cunha; Graham, Jove; Rodrigues, Laura; Fernandes, Rafael Lima; Barreto, Maurício Lima

2015-12-01

Several factors suggest that armadillos present an important risk for human leprosy infection. This study uses semi-structured interviews to better illustrate how human interaction with armadillos may increase the risk of leprosy transmission. The participants were all residents of the state of Ceará, in northeastern Brazil, all acknowledged contact with armadillos either through hunting, through cooking, or through consumption of its meat. This study raises important issues about contact between human beings and armadillos. The interviews provide evidence of numerous situations in which leprosy transmission via the armadillo is possible. At a minimum, people who hunt armadillos need to be made aware of the risk of infection. Copyright © 2015. Published by Elsevier B.V.

47 CFR 25.212 - Narrowband analog transmissions, digital transmissions, and video transmissions in the GSO Fixed...

Code of Federal Regulations, 2012 CFR

2012-10-01

... transmissions, and video transmissions in the GSO Fixed-Satellite Service. 25.212 Section 25.212... Technical Standards § 25.212 Narrowband analog transmissions, digital transmissions, and video transmissions... narrowband and/or wideband digital services, including digital video services, if the maximum input spectral...

47 CFR 25.212 - Narrowband analog transmissions, digital transmissions, and video transmissions in the GSO Fixed...

Code of Federal Regulations, 2010 CFR

2010-10-01

... transmissions, and video transmissions in the GSO Fixed-Satellite Service. 25.212 Section 25.212... Technical Standards § 25.212 Narrowband analog transmissions, digital transmissions, and video transmissions... narrowband and/or wideband digital services, including digital video services, if the maximum input spectral...

47 CFR 25.212 - Narrowband analog transmissions, digital transmissions, and video transmissions in the GSO Fixed...

Code of Federal Regulations, 2011 CFR

2011-10-01

... transmissions, and video transmissions in the GSO Fixed-Satellite Service. 25.212 Section 25.212... Technical Standards § 25.212 Narrowband analog transmissions, digital transmissions, and video transmissions... narrowband and/or wideband digital services, including digital video services, if the maximum input spectral...

The association of drinking water quality and sewage disposal with Helicobacter pylori incidence in infants: the potential role of water-borne transmission.

PubMed

Travis, Penny B; Goodman, Karen J; O'Rourke, Kathleen M; Groves, Frank D; Sinha, Debajyoti; Nicholas, Joyce S; VanDerslice, Jim; Lackland, Daniel; Mena, Kristina D

2010-03-01

The mode of transmission of Helicobacter pylori, a bacterium causing gastric cancer and peptic ulcer disease, is unknown although waterborne transmission is a likely pathway. This study investigated the hypothesis that access to treated water and a sanitary sewerage system reduces the H. pylori incidence rate, using data from 472 participants in a cohort study that followed children in Juarez, Mexico, and El Paso, Texas, from April 1998, with caretaker interviews and the urea breath test for detecting H. pylori infection at target intervals of six months from birth through 24 months of age. The unadjusted hazard ratio comparing bottled/vending machine water to a municipal water supply was 0.71 (95% confidence interval (CI): 0.50, 1.01) and comparing a municipal sewer connection to a septic tank or cesspool, 0.85 (95% CI: 0.60, 1.20). After adjustment for maternal education and country, the hazard ratios decreased slightly to 0.70 (95% confidence interval: 0.49, 1.00) and 0.77 (95% confidence interval: 0.50, 1.21), respectively. These results provide moderate support for potential waterborne transmission of H. pylori.

Breaking beta: deconstructing the parasite transmission function

PubMed Central

McCallum, Hamish; Fenton, Andy; Hudson, Peter J.; Lee, Brian; Levick, Beth; Norman, Rachel

2017-01-01

Transmission is a fundamental step in the life cycle of every parasite but it is also one of the most challenging processes to model and quantify. In most host–parasite models, the transmission process is encapsulated by a single parameter β. Many different biological processes and interactions, acting on both hosts and infectious organisms, are subsumed in this single term. There are, however, at least two undesirable consequences of this high level of abstraction. First, nonlinearities and heterogeneities that can be critical to the dynamic behaviour of infections are poorly represented; second, estimating the transmission coefficient β from field data is often very difficult. In this paper, we present a conceptual model, which breaks the transmission process into its component parts. This deconstruction enables us to identify circumstances that generate nonlinearities in transmission, with potential implications for emergent transmission behaviour at individual and population scales. Such behaviour cannot be explained by the traditional linear transmission frameworks. The deconstruction also provides a clearer link to the empirical estimation of key components of transmission and enables the construction of flexible models that produce a unified understanding of the spread of both micro- and macro-parasite infectious disease agents. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289252

Modulation of transient receptor potential vanilloid 4-mediated membrane currents and synaptic transmission by protein kinase C

PubMed Central

Cao, De-Shou; Yu, Shuang-Quan; Premkumar, Louis S

2009-01-01

Background Transient receptor potential Vanilloid (TRPV) receptors are involved in nociception and are expressed predominantly in sensory neurons. TRPV1, a non-selective cation channel has been extensively studied and is responsible for inflammatory thermal hypersensitivity. In this study, the expression and function of TRPV4 have been characterized and compared with those of TRPV1. Results Immunohistochemical studies revealed that both TRPV1 and TRPV4 were co-expressed in dorsal root ganglion (DRG) neuronal cell bodies and in the central terminals of laminae I and II of the spinal dorsal horn (DH). In Ca2+ fluorescence imaging and whole-cell patch-clamp experiments, TRPV1- and TRPV4-mediated responses were observed in a population of the same DRG neurons. Sensitization of TRPV1 has been shown to be involved in inflammatory pain conditions. Incubation with phorbol 12, 13-dibutyrate (PDBu), a PKC activator, resulted in a significant potentiation of TRPV4 currents in DRG neurons. In TRPV4 expressing HEK 293T cells, PDBu increased 4α-phorbol 12, 13-didecanoate (4α-PDD)-induced single-channel activity in cell-attached patches, which was abrogated by bisindolylmaleimide (BIM), a selective PKC inhibitor. TRPV4 is also expressed at the central terminals of sensory neurons. Activation of TRPV4 by 4α-PDD increased the frequency of miniature excitatory post synaptic currents (mEPSCs) in DRG-DH neuronal co-cultures. 4α-PDD-induced increase in the frequency of mEPSCs was further enhanced by PDBu. The expression of TRP channels has been shown in other areas of the CNS; application of 4α-PDD significantly increased the mEPSC frequency in cultured hippocampal neurons, which was further potentiated by PDBu, whereas, TRPV1 agonist capsaicin did not modulate synaptic transmission. Conclusion These results indicate that TRPV4 and TRPV1 are co-expressed in certain DRG neurons and TRPV4 can be sensitized by PKC not only in DRG neuronal cell bodies, but also in the central sensory

Tuberculosis transmission in the Indigenous peoples of the Canadian prairies

PubMed Central

Patel, Smit; Paulsen, Catherine; Heffernan, Courtney; Saunders, Duncan; Sharma, Meenu; King, Malcolm; Hoeppner, Vernon; Orr, Pamela; Kunimoto, Dennis; Menzies, Dick; Christianson, Sara; Wolfe, Joyce; Boffa, Jody; McMullin, Kathleen; Lopez-Hille, Carmen; Senthilselvan, Ambikaipakan

2017-01-01

Setting The prairie provinces of Canada. Objective To characterize tuberculosis (TB) transmission among the Indigenous and non-Indigenous Canadian-born peoples of the prairie provinces of Canada. Design A prospective epidemiologic study of consecutively diagnosed adult (age ≥ 14 years) Canadian-born culture-positive pulmonary TB cases on the prairies, hereafter termed “potential transmitters,” and the transmission events generated by them. “Transmission events” included new positive tuberculin skin tests (TSTs), TST conversions, and secondary cases among contacts. Results In the years 2007 and 2008, 222 potential transmitters were diagnosed on the prairies. Of these, the vast majority (198; 89.2%) were Indigenous peoples who resided in either an Indigenous community (135; 68.2%) or a major metropolitan area (44; 22.2%). Over the 4.5-year period between July 1st, 2006 and December 31st 2010, 1085 transmission events occurred in connection with these potential transmitters. Most of these transmission events were attributable to potential transmitters who identified as Indigenous (94.5%). With a few notable exceptions most transmitters and their infected contacts resided in the same community type. In multivariate models positive smear status and a higher number of close contacts were associated with increased transmission; adjusted odds ratios (ORs) and 95% confidence intervals (CIs), 4.30 [1.88, 9.84] and 2.88 [1.31, 6.34], respectively. Among infected contacts, being Indigenous was associated with disease progression; OR and 95% CI, 3.59 [1.27, 10.14] and 6.89 [2.04, 23.25] depending upon Indigenous group, while being an infected casual contact was less likely than being a close contact to be associated with disease progression, 0.66 [0.44, 1.00]. Conclusion In the prairie provinces of Canada and among Canadian-born persons, Indigenous peoples account for the vast majority of cases with the potential to transmit as well as the vast majority of infected

Tuberculosis transmission in the Indigenous peoples of the Canadian prairies.

PubMed

Patel, Smit; Paulsen, Catherine; Heffernan, Courtney; Saunders, Duncan; Sharma, Meenu; King, Malcolm; Hoeppner, Vernon; Orr, Pamela; Kunimoto, Dennis; Menzies, Dick; Christianson, Sara; Wolfe, Joyce; Boffa, Jody; McMullin, Kathleen; Lopez-Hille, Carmen; Senthilselvan, Ambikaipakan; Long, Richard

2017-01-01

The prairie provinces of Canada. To characterize tuberculosis (TB) transmission among the Indigenous and non-Indigenous Canadian-born peoples of the prairie provinces of Canada. A prospective epidemiologic study of consecutively diagnosed adult (age ≥ 14 years) Canadian-born culture-positive pulmonary TB cases on the prairies, hereafter termed "potential transmitters," and the transmission events generated by them. "Transmission events" included new positive tuberculin skin tests (TSTs), TST conversions, and secondary cases among contacts. In the years 2007 and 2008, 222 potential transmitters were diagnosed on the prairies. Of these, the vast majority (198; 89.2%) were Indigenous peoples who resided in either an Indigenous community (135; 68.2%) or a major metropolitan area (44; 22.2%). Over the 4.5-year period between July 1st, 2006 and December 31st 2010, 1085 transmission events occurred in connection with these potential transmitters. Most of these transmission events were attributable to potential transmitters who identified as Indigenous (94.5%). With a few notable exceptions most transmitters and their infected contacts resided in the same community type. In multivariate models positive smear status and a higher number of close contacts were associated with increased transmission; adjusted odds ratios (ORs) and 95% confidence intervals (CIs), 4.30 [1.88, 9.84] and 2.88 [1.31, 6.34], respectively. Among infected contacts, being Indigenous was associated with disease progression; OR and 95% CI, 3.59 [1.27, 10.14] and 6.89 [2.04, 23.25] depending upon Indigenous group, while being an infected casual contact was less likely than being a close contact to be associated with disease progression, 0.66 [0.44, 1.00]. In the prairie provinces of Canada and among Canadian-born persons, Indigenous peoples account for the vast majority of cases with the potential to transmit as well as the vast majority of infected contacts. Active case finding and preventative therapy

An Analysis of the Potential Impact of Climate Change on Dengue Transmission in the Southeastern United States.

PubMed

Butterworth, Melinda K; Morin, Cory W; Comrie, Andrew C

2017-04-01

Dengue fever, caused by a mosquito-transmitted virus, is an increasing health concern in the Americas. Meteorological variables such as temperature and precipitation can affect disease distribution and abundance through biophysical impacts on the vector and on the virus. Such tightly coupled links may facilitate further spread of dengue fever under a changing climate. In the southeastern United States, the dengue vector is widely established and exists on the current fringe of dengue transmission. We assessed projected climate change-driven shifts in dengue transmission risk in this region. We used a dynamic mosquito population and virus transmission model driven by meteorological data to simulate Aedes aegypti populations and dengue cases in 23 locations in the southeastern United States under current climate conditions and future climate projections. We compared estimates for each location with simulations based on observed data from San Juan, Puerto Rico, where dengue is endemic. Our simulations based on current climate data suggest that dengue transmission at levels similar to those in San Juan is possible at several U.S. locations during the summer months, particularly in southern Florida and Texas. Simulations that include climate change projections suggest that conditions may become suitable for virus transmission in a larger number of locations and for a longer period of time during each year. However, in contrast with San Juan, U.S. locations would not sustain year-round dengue transmission according to our model. Our findings suggest that Dengue virus (DENV) transmission is limited by low winter temperatures in the mainland United States, which are likely to prevent its permanent establishment. Although future climate conditions may increase the length of the mosquito season in many locations, projected increases in dengue transmission are limited to the southernmost locations.

An analytical method for designing low noise helicopter transmissions

NASA Technical Reports Server (NTRS)

Bossler, R. B., Jr.; Bowes, M. A.; Royal, A. C.

1978-01-01

The development and experimental validation of a method for analytically modeling the noise mechanism in the helicopter geared power transmission systems is described. This method can be used within the design process to predict interior noise levels and to investigate the noise reducing potential of alternative transmission design details. Examples are discussed.

Predicting optimal transmission investment in malaria parasites

PubMed Central

Greischar, Megan A.; Mideo, Nicole; Read, Andrew F.; Bjørnstad, Ottar N.

2016-01-01

In vertebrate hosts, malaria parasites face a tradeoff between replicating and the production of transmission stages that can be passed onto mosquitoes. This tradeoff is analogous to growth-reproduction tradeoffs in multicellular organisms. We use a mathematical model tailored to the life cycle and dynamics of malaria parasites to identify allocation strategies that maximize cumulative transmission potential to mosquitoes. We show that plastic strategies can substantially outperform fixed allocation because parasites can achieve greater fitness by investing in proliferation early and delaying the production of transmission stages. Parasites should further benefit from restraining transmission investment later in infection, because such a strategy can help maintain parasite numbers in the face of resource depletion. Early allocation decisions are predicted to have the greatest impact on parasite fitness. If the immune response saturates as parasite numbers increase, parasites should benefit from even longer delays prior to transmission investment. The presence of a competing strain selects for consistently lower levels of transmission investment and dramatically increased exploitation of the red blood cell resource. While we provide a detailed analysis of tradeoffs pertaining to malaria life history, our approach for identifying optimal plastic allocation strategies may be broadly applicable. PMID:27271841

Ecology of potential West Nile virus vectors in southeastern Louisiana: enzootic transmission in the relative absence of Culex quinquefasciatus

USGS Publications Warehouse

Godsey, Marvin S.; King, Raymond J.; Burkhalter, Kristen; Delorey, Mark; Colton, Leah; Charnetzky, Dawn; Sutherland, Genevieve; Ezenwa, Vanessa O.; Wilson, Lawrence A.; Coffey, Michelle; Milheim, Lesley E.; Taylor, Viki G.; Palmisano, Charles; Wesson, Dawn M.; Guptill, Stephen C.

2013-01-01

A study of West Nile virus (WNV) ecology was conducted in St. Tammany Parish, Louisiana, from 2002 to 2004. Mosquitoes were collected weekly throughout the year using Centers for Disease Control and Prevention (CDC) light traps placed at 1.5 and 6 m above the ground and gravid traps. A total of 379,466 mosquitoes was collected. WNV was identified in 32 pools of mosquitoes comprising four species; 23 positive pools were from Culex nigripalpus collected during 2003. Significantly more positive pools were obtained from Cx. nigripalpus collected in traps placed at 6 m than 1.5 m that year, but abundance did not differ by trap height. In contrast, Cx. nigripalpus abundance was significantly greater in traps placed at 6 m in 2002 and 2004. Annual temporal variation in Cx. nigripalpus peak seasonal abundance has important implications for WNV transmission in Louisiana. One WNV-positive pool, from Cx. erraticus, was collected during the winter of 2004, showing year-round transmission. The potential roles of additional mosquito species in WNV transmission in southeastern Louisiana are discussed. Disclaimer: The opinions expressed in this article are the opinions of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. This article has been peer reviewed and approved for publication consistent with U.S. Geological Survey Fundamental Science Practices (http//pubs.usgs.gov/circ/1367/). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Small passenger car transmission test-Chevrolet 200 transmission

NASA Technical Reports Server (NTRS)

Bujold, M. P.

1980-01-01

The small passenger car transmission was tested to supply electric vehicle manufacturers with technical information regarding the performance of commerically available transmissions which would enable them to design a more energy efficient vehicle. With this information the manufacturers could estimate vehicle driving range as well as speed and torque requirements for specific road load performance characteristics. A 1979 Chevrolet Model 200 automatic transmission was tested per a passenger car automatic transmission test code (SAE J651b) which required drive performance, coast performance, and no load test conditions. The transmission attained maximum efficiencies in the mid-eighty percent range for both drive performance tests and coast performance tests. Torque, speed and efficiency curves map the complete performance characteristics for Chevrolet Model 200 transmission.

Malaria transmission blocking immunity and sexual stage vaccines for interrupting malaria transmission in Latin America

PubMed Central

Arévalo-Herrera, Myriam; Solarte, Yezid; Marin, Catherin; Santos, Mariana; Castellanos, Jenniffer; Beier, John C; Valencia, Sócrates Herrera

2016-01-01

Malaria is a vector-borne disease that is considered to be one of the most serious public health problems due to its high global mortality and morbidity rates. Although multiple strategies for controlling malaria have been used, many have had limited impact due to the appearance and rapid dissemination of mosquito resistance to insecticides, parasite resistance to multiple antimalarial drug, and the lack of sustainability. Individuals in endemic areas that have been permanently exposed to the parasite develop specific immune responses capable of diminishing parasite burden and the clinical manifestations of the disease, including blocking of parasite transmission to the mosquito vector. This is referred to as transmission blocking (TB) immunity (TBI) and is mediated by specific antibodies and other factors ingested during the blood meal that inhibit parasite development in the mosquito. These antibodies recognize proteins expressed on either gametocytes or parasite stages that develop in the mosquito midgut and are considered to be potential malaria vaccine candidates. Although these candidates, collectively called TB vaccines (TBV), would not directly stop malaria from infecting individuals, but would stop transmission from infected person to non-infected person. Here, we review the progress that has been achieved in TBI studies and the development of TBV and we highlight their potential usefulness in areas of low endemicity such as Latin America. PMID:21881775

HIV Transmission Dynamics Among Foreign-Born Persons in the United States.

PubMed

Valverde, Eduardo E; Oster, Alexandra M; Xu, Songli; Wertheim, Joel O; Hernandez, Angela L

2017-12-15

In the United States (US), foreign-born persons are disproportionately affected by HIV and differ epidemiologically from US-born persons with diagnosed HIV infection. Understanding HIV transmission dynamics among foreign-born persons is important to guide HIV prevention efforts for these populations. We conducted molecular transmission network analysis to describe HIV transmission dynamics among foreign-born persons with diagnosed HIV. Using HIV-1 polymerase nucleotide sequences reported to the US National HIV Surveillance System for persons with diagnosed HIV infection during 2001-2013, we constructed a genetic distance-based transmission network using HIV-TRACE and examined the birth region of potential transmission partners in this network. Of 77,686 people, 12,064 (16%) were foreign born. Overall, 28% of foreign-born persons linked to at least one other person in the transmission network. Of potential transmission partners, 62% were born in the United States, 31% were born in the same region as the foreign-born person, and 7% were born in another region of the world. Most transmission partners of male foreign-born persons (63%) were born in the United States, whereas most transmission partners of female foreign-borns (57%) were born in their same world region. These finding suggests that a majority of HIV infections among foreign-born persons in our network occurred after immigrating to the United States. Efforts to prevent HIV infection among foreign-born persons in the United States should include information of the transmission networks in which these individuals acquire or transmit HIV to develop more targeted HIV prevention interventions.

Automatic remote monitoring utilizing daily transmissions: transmission reliability and implantable cardioverter defibrillator battery longevity in the TRUST trial.

PubMed

Varma, Niraj; Love, Charles J; Schweikert, Robert; Moll, Philip; Michalski, Justin; Epstein, Andrew E

2018-04-01

Benefits of automatic remote home monitoring (HM) among implantable cardioverter defibrillator (ICD) patients may require high transmission frequency. However, transmission reliability and effects on battery longevity remain uncertain. We hypothesized that HM would have high transmission success permitting punctual guideline based follow-up, and improve battery longevity. This was tested in the prospective randomized TRUST trial. Implantable cardioverter defibrillator patients were randomized post-implant 2:1 to HM (n = 908) (transmit daily) or to Conventional in-person monitoring [conventional management (CM), n = 431 (HM disabled)]. In both groups, five evaluations were scheduled every 3 months for 15 months. Home Monitoring technology performance was assessed by transmissions received vs. total possible, and number of scheduled HM checks failing because of missed transmissions. Battery longevity was compared in HM vs. CM at 15 months, and again in HM 3 years post-implant using continuously transmitted data. Transmission success per patient was 91% (median follow-up of 434 days). Overall, daily HM transmissions were received in 315 795 of a potential 363 450 days (87%). Only 55/3759 (1.46%) of unsuccessful scheduled evaluations in HM were attributed to transmission loss. Shock frequency and pacing percentage were similar in HM vs. CM. Fifteen month battery longevity was 12% greater in HM (93.2 ± 8.8% vs. 83.5 ± 6.0% CM, P < 0.001). In extended follow-up of HM patients, estimated battery longevity was 50.9 ± 9.1% (median 52%) at 36 months. Automatic remote HM demonstrated robust transmission reliability. Daily transmission load may be sustained without reducing battery longevity. Home Monitoring conserves battery longevity and tracks long term device performance. ClinicalTrials.gov; NCT00336284.

Note: A unibody NIR transmission probe for in situ liquid detection

NASA Astrophysics Data System (ADS)

Wang, Huijie; Wang, Yang; Ma, Xiangyun; Zhao, Yang; Chen, Da; Chen, Wenliang; Xu, Kexin; Li, Qifeng

2018-03-01

The transmission probe is widely used for in situ spectroscopic detection in various fields. Conventional transmission probes are always assembled from parts, which require accurate assembly and good sealing. In this paper, a universal and reliable near-infrared (NIR) transmission probe is proposed, which is simply made up of a unibody fused silica rod. The proposed NIR transmission probe has been successfully used to measure the alcohol by volume of the Chinese spirit for quality control. This unibody NIR transmission probe has great potential for the detection of corrosive substances, owing to the good chemical resistance.

Social transmission of nectar-robbing behaviour in bumble-bees

PubMed Central

Leadbeater, Ellouise; Chittka, Lars

2008-01-01

Social transmission of acquired foraging techniques is rarely considered outside of a vertebrate context. Here, however, we show that nectar robbing by bumble-bees (Bombus terrestris)—an invertebrate behaviour of considerable ecological significance—has the potential to spread through a population at the accelerated rates typical of social transmission. Nectar robbing occurs when individuals either bite through the base of a flower to ‘steal’ nectar (primary robbing) or use robbing holes that others have made (secondary robbing). We found that experience of foraging from robbed flowers significantly promoted the development of primary robbing in previously legitimate foragers, thus implying that the acquisition of nectar robbing by one individual will facilitate its adoption in others. Our findings suggest that the positive feedback effects of social transmission may potentially play an ecologically important role in the relationship between plants and pollinators. PMID:18430642

Potential for Waterborne and Invertebrate Transmission of West Nile Virus in the Great Salt Lake, Utah.

PubMed

Lund, Melissa; Shearn-Bochsler, Valerie; Dusek, Robert J; Shivers, Jan; Hofmeister, Erik

2017-07-15

In November and December of 2013, a large mortality event involving 15,000 to 20,000 eared grebes ( Podiceps nigricollis ) occurred at the Great Salt Lake (GSL), UT. The onset of the outbreak in grebes was followed by a mortality event in >86 bald eagles ( Haliaeetus leucocephalus ). During the die-off, West Nile virus (WNV) was detected by reverse transcription-PCR (RT-PCR) or viral culture in the carcasses of grebes and eagles submitted to the National Wildlife Health Center. However, no activity of mosquitoes, the primary vectors of WNV, was detected by the State of Utah's WNV monitoring program. The transmission of WNV has rarely been reported during the winter in North America in the absence of known mosquito activity; however, the size of this die-off, the habitat in which it occurred, and the species involved are unique. We experimentally investigated whether WNV could survive in water with a high salt content, as found at the GSL, and whether brine shrimp, the primary food of migrating eared grebes on the GSL, could have played a role in the transmission of WNV to feeding birds. We found that WNV can survive up to 72 h at 4°C in water containing 30 to 150 ppt NaCl, and brine shrimp incubated with WNV in 30 ppt NaCl may adsorb WNV to their cuticle and, through feeding, infect epithelial cells of their gut. Both mechanisms may have potentiated the WNV die-off in migrating eared grebes on the GSL. IMPORTANCE Following a major West Nile virus die-off of eared grebes and bald eagles at the Great Salt Lake (GSL), UT, in November to December 2013, this study assessed the survival of West Nile virus (WNV) in water as saline as that of the GSL and whether brine shrimp, the major food for migrating grebes, could have played a role as a vector for the virus. While mosquitoes are the major vector of WNV, under certain circumstances, transmission may occur through contaminated water and invertebrates as food. Copyright © 2017 American Society for Microbiology.

Pulse transmission receiver with higher-order time derivative pulse correlator

DOEpatents

Dress, Jr., William B.; Smith, Stephen F.

2003-09-16

Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a higher-order time derivative pulse correlator; a demodulation decoder coupled to the higher-order time derivative pulse correlator; a clock coupled to the demodulation decoder; and a pseudorandom polynomial generator coupled to both the higher-order time derivative pulse correlator and the clock. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

Potential Sources and Transmission of Salmonella and Antimicrobial Resistance in Kampala, Uganda

PubMed Central

Afema, Josephine A.; Byarugaba, Denis K.; Shah, Devendra H.; Atukwase, Esther; Nambi, Maria; Sischo, William M.

2016-01-01

In sub‒Saharan Africa, non‒typhoidal Salmonellae (NTS) cause invasive disease particularly in children and HIV infected adults, but the disease epidemiology is poorly understood. Between 2012 and 2013, we investigated NTS sources and transmission in Kampala. We detected Salmonella in 60% of the influent and 60% of the effluent samples from a wastewater treatment plant and 53.3% of the influent and 10% of the effluent samples from waste stabilization ponds that serve the human population; 40.9% of flush‒water samples from ruminant slaughterhouses, 6.6% of the poultry fecal samples from live bird markets and 4% of the fecal samples from swine at slaughter; and in 54.2% of the water samples from a channel that drains storm–water and effluents from the city. We obtained 775 Salmonella isolates, identified 32 serovars, and determined resistance to 15 antimicrobials. We genotyped common serovars using multiple‒locus variable number tandem repeats analysis or pulsed‒field gel electrophoresis. In addition, we analyzed 49 archived NTS isolates from asymptomatic livestock and human clinical cases. Salmonella from ruminant and swine sources were mostly pan‒susceptible (95%) while poultry isolates were generally more resistant. Salmonella Kentucky isolated from poultry exhibited extensive drug resistance characterized by resistance to 10 antimicrobials. Interestingly, similar genotypes of S. Kentucky but with less antimicrobial resistance (AMR) were found in poultry, human and environmental sources. The observed AMR patterns could be attributed to host or management factors associated with production. Alternatively, S. Kentucky may be prone to acquiring AMR. The factors driving AMR remain poorly understood and should be elucidated. Overall, shared genotypes and AMR phenotypes were found in NTS from human, livestock and environmental sources, suggesting zoonotic and environmental transmissions most likely occur. Information from this study could be used to control

Exosome-Mediated Pathogen Transmission by Arthropod Vectors.

PubMed

Hackenberg, Michael; Kotsyfakis, Michail

2018-04-24

Recent molecular and cellular studies have highlighted a potentially important role for tick exosomes in parasite transmission. Here we summarize evolving hypotheses about the largely unknown cellular events that may take place at the tick-host-pathogen interface, focusing on a potential role for arthropod exosomes in this tripartite interaction. Copyright © 2018 Elsevier Ltd. All rights reserved.

Terrestrial Dispersal and Potential Environmental Transmission of the Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis)

PubMed Central

Kolby, Jonathan E.; Ramirez, Sara D.; Berger, Lee; Richards-Hrdlicka, Kathryn L.; Jocque, Merlijn; Skerratt, Lee F.

2015-01-01

Dispersal and exposure to amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) is not confined to the aquatic habitat, but little is known about pathways that facilitate exposure to wild terrestrial amphibians that do not typically enter bodies of water. We explored the possible spread of Bd from an aquatic reservoir to terrestrial substrates by the emergence of recently metamorphosed infected amphibians and potential deposition of Bd-positive residue on riparian vegetation in Cusuco National Park, Honduras (CNP). Amphibians and their respective leaf perches were both sampled for Bd presence and the pathogen was detected on 76.1% (35/46) of leaves where a Bd-positive frog had rested. Although the viability of Bd detected on these leaves cannot be discerned from our quantitative PCR results, the cool air temperature, closed canopy, and high humidity of this cloud forest environment in CNP is expected to encourage pathogen persistence. High prevalence of infection (88.5%) detected in the recently metamorphosed amphibians and frequent shedding of Bd-positive residue on foliage demonstrates a pathway of Bd dispersal between aquatic and terrestrial habitats. This pathway provides the opportunity for environmental transmission of Bd among and between amphibian species without direct physical contact or exposure to an aquatic habitat. PMID:25927835

Effectively Communicating the Uncertainties Surrounding Ebola Virus Transmission.

PubMed

Kilianski, Andy; Evans, Nicholas G

2015-10-01

The current Ebola virus outbreak has highlighted the uncertainties surrounding many aspects of Ebola virus virology, including routes of transmission. The scientific community played a leading role during the outbreak-potentially, the largest of its kind-as many of the questions surrounding ebolaviruses have only been interrogated in the laboratory. Scientists provided an invaluable resource for clinicians, public health officials, policy makers, and the lay public in understanding the progress of Ebola virus disease and the continuing outbreak. Not all of the scientific communication, however, was accurate or effective. There were multiple instances of published articles during the height of the outbreak containing potentially misleading scientific language that spurred media overreaction and potentially jeopardized preparedness and policy decisions at critical points. Here, we use articles declaring the potential for airborne transmission of Ebola virus as a case study in the inaccurate reporting of basic science, and we provide recommendations for improving the communication about unknown aspects of disease during public health crises.

The potential impact of integrated malaria transmission control on entomologic inoculation rate in highly endemic areas.

PubMed

Killeen, G F; McKenzie, F E; Foy, B D; Schieffelin, C; Billingsley, P F; Beier, J C

2000-05-01

We have used a relatively simple but accurate model for predicting the impact of integrated transmission control on the malaria entomologic inoculation rate (EIR) at four endemic sites from across sub-Saharan Africa and the southwest Pacific. The simulated campaign incorporated modestly effective vaccine coverage, bed net use, and larval control. The results indicate that such campaigns would reduce EIRs at all four sites by 30- to 50-fold. Even without the vaccine, 15- to 25-fold reductions of EIR were predicted, implying that integrated control with a few modestly effective tools can meaningfully reduce malaria transmission in a range of endemic settings. The model accurately predicts the effects of bed nets and indoor spraying and demonstrates that they are the most effective tools available for reducing EIR. However, the impact of domestic adult vector control is amplified by measures for reducing the rate of emergence of vectors or the level of infectiousness of the human reservoir. We conclude that available tools, including currently neglected methods for larval control, can reduce malaria transmission intensity enough to alleviate mortality. Integrated control programs should be implemented to the fullest extent possible, even in areas of intense transmission, using simple models as decision-making tools. However, we also conclude that to eliminate malaria in many areas of intense transmission is beyond the scope of methods which developing nations can currently afford. New, cost-effective, practical tools are needed if malaria is ever to be eliminated from highly endemic areas.

Potential for water borne and invertebrate transmission of West Nile virus in the Great Salt Lake, Utah

USGS Publications Warehouse

Lund, Melissa; Shearn-Bochsler, Valerie I.; Dusek, Robert; Shivers, Jan; Hofmeister, Erik K.

2017-01-01

In November and December of 2013, a large mortality event involving 15,000 - 20,000 eared grebes (Podiceps nigricollis) occurred at the Great Salt Lake (GSL), UT. The onset of the outbreak in grebes was followed by a mortality event in > 86 bald eagles (Haliaeetus leucocephalus). During the die-off, West Nile virus (WNV) was detected by RT-PCR or viral culture in carcasses of grebes and eagles submitted to the National Wildlife Health Center. However, no mosquito activity, the primary vector of WNV, was detected by the State of Utah's WNV monitoring program. Transmission of WNV has rarely been reported during the winter in North America in the absence of known mosquito activity; however, the size of this die-off, the habitat in which it occurred, and the species involved are unique. We experimentally investigated whether WNV could survive in water with a high saline content, as found at the GSL, and whether brine shrimp, the primary food of migrating eared grebes on the GSL, could have played a role in transmission of WNV to feeding birds. We found that WNV can survive up to 72 h at 4°C in water containing 30 — 150 ppt NaCl and brine shrimp, incubated with WNV in 30 ppt NaCl, may adsorb WNV to their cuticle and, through feeding, may infect epithelial cells of their gut. Both mechanisms may have potentiated the WNV die-off in migrating eared grebes on the GSL.

Small passenger car transmission test: Mercury Lynx ATX transmission

NASA Technical Reports Server (NTRS)

Bujold, M. P.

1981-01-01

The testing of a Mercury Lynx automatic transmission is reported. The transmission was tested in accordance with a passenger car automatic transmission test code (SAE J65lb) which required drive performance, coast performance, and no load test conditions. Under these conditions, the transmission attained maximum efficiencies in the mid-ninety percent range both for drive performance test and coast performance tests. The torque, speed, and efficiency curves are presented, which provide the complete performance characteristics for the Mercury Lynx automatic transmission.

Reducing Wind Curtailment through Transmission Expansion in a Wind Vision Future

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jorgensen, Jennie; Mai, Trieu; Brinkman, Greg

The Department of Energy's 2015 Wind Vision study, which analyzed an ambitious scenario where wind power served 35% of U.S. electricity consumption in 2050, showed the potential for wind energy to provide substantial health, environmental, and economic benefits. Using a commercial unit commitment and economic dispatch model, we build on this research by assessing the hourly operational feasibility of a similar high wind future in the Western United States. Our detailed simulations found no hours of unmet load or reserve violations with more than 35% potential wind (and 12% potential solar) available on the system, which highlights the technical possibilitymore » of integrating large amounts of wind energy. However, absent significant changes to the western grid, we find that substantial wind curtailment could be an issue, as it could degrade the potential for wind power to reduce fuel costs and lowering the emission benefits. To assess the value of transmission to mitigate wind curtailment, we model a suite of transmission expansion scenarios. We find that wind curtailment could be reduced by approximately half under a scenario where new transmission is based only on proposed projects. This avoided wind curtailment could lower annual production costs and reduce carbon dioxide emissions substantially. Greater transmission expansion was found to yield further benefits, although the marginal benefits of these new lines were found to decline. Overall, these results suggest that power systems operation can be realized with more than 35% wind penetration, but that transmission expansion is likely to play a vital role.« less

A second transmissible cancer in Tasmanian devils.

PubMed

Pye, Ruth J; Pemberton, David; Tovar, Cesar; Tubio, Jose M C; Dun, Karen A; Fox, Samantha; Darby, Jocelyn; Hayes, Dane; Knowles, Graeme W; Kreiss, Alexandre; Siddle, Hannah V T; Swift, Kate; Lyons, A Bruce; Murchison, Elizabeth P; Woods, Gregory M

2016-01-12

Clonally transmissible cancers are somatic cell lineages that are spread between individuals via the transfer of living cancer cells. There are only three known naturally occurring transmissible cancers, and these affect dogs, soft-shell clams, and Tasmanian devils, respectively. The Tasmanian devil transmissible facial cancer was first observed in 1996, and is threatening its host species with extinction. Until now, this disease has been consistently associated with a single aneuploid cancer cell lineage that we refer to as DFT1. Here we describe a second transmissible cancer, DFT2, in five devils located in southern Tasmania in 2014 and 2015. DFT2 causes facial tumors that are grossly indistinguishable but histologically distinct from those caused by DFT1. DFT2 bears no detectable cytogenetic similarity to DFT1 and carries a Y chromosome, which contrasts with the female origin of DFT1. DFT2 shows different alleles to both its hosts and DFT1 at microsatellite, structural variant, and major histocompatibility complex (MHC) loci, confirming that it is a second cancer that can be transmitted between devils as an allogeneic, MHC-discordant graft. These findings indicate that Tasmanian devils have spawned at least two distinct transmissible cancer lineages and suggest that transmissible cancers may arise more frequently in nature than previously considered. The discovery of DFT2 presents important challenges for the conservation of Tasmanian devils and raises the possibility that this species is particularly prone to the emergence of transmissible cancers. More generally, our findings highlight the potential for cancer cells to depart from their hosts and become dangerous transmissible pathogens.

Small passenger car transmission test; Chevrolet LUV transmission

NASA Technical Reports Server (NTRS)

Bujold, M. P.

1980-01-01

A 1978 Chevrolet LUV manual transmission tested per the applicable portions of a passenger car automatic transmission test code (SAE J65lb) which required drive performance, coast performance, and no load test conditions. Under these test conditions, the transmission attained maximum efficiencies in the upper ninety percent range for both drive performance tests and coast performance tests. The major results of this test (torque, speed, and efficiency curves) are presented. Graphs map the complete performance characteristics for the Chevrolet LUV transmission.

Decreased prefrontal cortical dopamine transmission in alcoholism.

PubMed

Narendran, Rajesh; Mason, Neale Scott; Paris, Jennifer; Himes, Michael L; Douaihy, Antoine B; Frankle, W Gordon

2014-08-01

Basic studies have demonstrated that optimal levels of prefrontal cortical dopamine are critical to various executive functions such as working memory, attention, inhibitory control, and risk/reward decisions, all of which are impaired in addictive disorders such as alcoholism. Based on this and imaging studies of alcoholism that have demonstrated less dopamine in the striatum, the authors hypothesized decreased dopamine transmission in the prefrontal cortex in persons with alcohol dependence. To test this hypothesis, amphetamine and [11C]FLB 457 positron emission tomography were used to measure cortical dopamine transmission in 21 recently abstinent persons with alcohol dependence and 21 matched healthy comparison subjects. [11C]FLB 457 binding potential, specific compared to nondisplaceable uptake (BPND), was measured in subjects with kinetic analysis using the arterial input function both before and after 0.5 mg kg-1 of d-amphetamine. Amphetamine-induced displacement of [11C]FLB 457 binding potential (ΔBPND) was significantly smaller in the cortical regions in the alcohol-dependent group compared with the healthy comparison group. Cortical regions that demonstrated lower dopamine transmission in the alcohol-dependent group included the dorsolateral prefrontal cortex, medial prefrontal cortex, orbital frontal cortex, temporal cortex, and medial temporal lobe. The results of this study, for the first time, unambiguously demonstrate decreased dopamine transmission in the cortex in alcoholism. Further research is necessary to understand the clinical relevance of decreased cortical dopamine as to whether it is related to impaired executive function, relapse, and outcome in alcoholism.

Pulse transmission receiver with higher-order time derivative pulse generator

DOEpatents

Dress, Jr., William B.; Smith, Stephen F.

2003-08-12

Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a front-end amplification/processing circuit; a synchronization circuit coupled to the front-end amplification/processing circuit; a clock coupled to the synchronization circuit; a trigger signal generator coupled to the clock; and at least one higher-order time derivative pulse generator coupled to the trigger signal generator. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

THE POTENTIAL IMPACT OF INTEGRATED MALARIA TRANSMISSION CONTROL ON ENTOMOLOGIC INOCULATION RATE IN HIGHLY ENDEMIC AREAS

PubMed Central

KILLEEN, GERRY F.; McKENZIE, F. ELLIS; FOY, BRIAN D.; SCHIEFFELIN, CATHERINE; BILLINGSLEY, PETER F.; BEIER, JOHN C.

2008-01-01

We have used a relatively simple but accurate model for predicting the impact of integrated transmission control on the malaria entomologic inoculation rate (EIR) at four endemic sites from across sub-Saharan Africa and the southwest Pacific. The simulated campaign incorporated modestly effective vaccine coverage, bed net use, and larval control. The results indicate that such campaigns would reduce EIRs at all four sites by 30- to 50-fold. Even without the vaccine, 15- to 25-fold reductions of EIR were predicted, implying that integrated control with a few modestly effective tools can meaningfully reduce malaria transmission in a range of endemic settings. The model accurately predicts the effects of bed nets and indoor spraying and demonstrates that they are the most effective tools available for reducing EIR. However, the impact of domestic adult vector control is amplified by measures for reducing the rate of emergence of vectors or the level of infectiousness of the human reservoir. We conclude that available tools, including currently neglected methods for larval control, can reduce malaria transmission intensity enough to alleviate mortality. Integrated control programs should be implemented to the fullest extent possible, even in areas of intense transmission, using simple models as decision-making tools. However, we also conclude that to eliminate malaria in many areas of intense transmission is beyond the scope of methods which developing nations can currently afford. New, cost-effective, practical tools are needed if malaria is ever to be eliminated from highly endemic areas. PMID:11289662

Pneumothorax effects on pulmonary acoustic transmission.

PubMed

Mansy, Hansen A; Balk, Robert A; Warren, William H; Royston, Thomas J; Dai, Zoujun; Peng, Ying; Sandler, Richard H

2015-08-01

Pneumothorax (PTX) is an abnormal accumulation of air between the lung and the chest wall. It is a relatively common and potentially life-threatening condition encountered in patients who are critically ill or have experienced trauma. Auscultatory signs of PTX include decreased breath sounds during the physical examination. The objective of this exploratory study was to investigate the changes in sound transmission in the thorax due to PTX in humans. Nineteen human subjects who underwent video-assisted thoracic surgery, during which lung collapse is a normal part of the surgery, participated in the study. After subjects were intubated and mechanically ventilated, sounds were introduced into their airways via an endotracheal tube. Sounds were then measured over the chest surface before and after lung collapse. PTX caused small changes in acoustic transmission for frequencies below 400 Hz. A larger decrease in sound transmission was observed from 400 to 600 Hz, possibly due to the stronger acoustic transmission blocking of the pleural air. At frequencies above 1 kHz, the sound waves became weaker and so did their changes with PTX. The study elucidated some of the possible mechanisms of sound propagation changes with PTX. Sound transmission measurement was able to distinguish between baseline and PTX states in this small patient group. Future studies are needed to evaluate this technique in a wider population. Copyright © 2015 the American Physiological Society.

Pneumothorax effects on pulmonary acoustic transmission

PubMed Central

Balk, Robert A.; Warren, William H.; Royston, Thomas J.; Dai, Zoujun; Peng, Ying; Sandler, Richard H.

2015-01-01

Pneumothorax (PTX) is an abnormal accumulation of air between the lung and the chest wall. It is a relatively common and potentially life-threatening condition encountered in patients who are critically ill or have experienced trauma. Auscultatory signs of PTX include decreased breath sounds during the physical examination. The objective of this exploratory study was to investigate the changes in sound transmission in the thorax due to PTX in humans. Nineteen human subjects who underwent video-assisted thoracic surgery, during which lung collapse is a normal part of the surgery, participated in the study. After subjects were intubated and mechanically ventilated, sounds were introduced into their airways via an endotracheal tube. Sounds were then measured over the chest surface before and after lung collapse. PTX caused small changes in acoustic transmission for frequencies below 400 Hz. A larger decrease in sound transmission was observed from 400 to 600 Hz, possibly due to the stronger acoustic transmission blocking of the pleural air. At frequencies above 1 kHz, the sound waves became weaker and so did their changes with PTX. The study elucidated some of the possible mechanisms of sound propagation changes with PTX. Sound transmission measurement was able to distinguish between baseline and PTX states in this small patient group. Future studies are needed to evaluate this technique in a wider population. PMID:26023225

Evidence for carry-over effects of predator exposure on pathogen transmission potential

PubMed Central

Roux, Olivier; Vantaux, Amélie; Roche, Benjamin; Yameogo, Koudraogo B.; Dabiré, Kounbobr R.; Diabaté, Abdoulaye; Simard, Frederic; Lefèvre, Thierry

2015-01-01

Accumulating evidence indicates that species interactions such as competition and predation can indirectly alter interactions with other community members, including parasites. For example, presence of predators can induce behavioural defences in the prey, resulting in a change in susceptibility to parasites. Such predator-induced phenotypic changes may be especially pervasive in prey with discrete larval and adult stages, for which exposure to predators during larval development can have strong carry-over effects on adult phenotypes. To the best of our knowledge, no study to date has examined possible carry-over effects of predator exposure on pathogen transmission. We addressed this question using a natural food web consisting of the human malaria parasite Plasmodium falciparum, the mosquito vector Anopheles coluzzii and a backswimmer, an aquatic predator of mosquito larvae. Although predator exposure did not significantly alter mosquito susceptibility to P. falciparum, it incurred strong fitness costs on other key mosquito life-history traits, including larval development, adult size, fecundity and longevity. Using an epidemiological model, we show that larval predator exposure should overall significantly decrease malaria transmission. These results highlight the importance of taking into account the effect of environmental stressors on disease ecology and epidemiology. PMID:26674956

A novel component of cannabis extract potentiates excitatory synaptic transmission in rat olfactory cortex in vitro.

PubMed

Whalley, Benjamin J; Wilkinson, Jonathan D; Williamson, Elizabeth M; Constanti, Andrew

2004-07-15

Cannabis is a potential treatment for epilepsy, although the few human studies supporting this use have proved inconclusive. Previously, we showed that a standardized cannabis extract (SCE), isolated Delta9-tetrahydrocannabinol (Delta9-THC), and even Delta9-THC-free SCE inhibited muscarinic agonist-induced epileptiform bursting in rat olfactory cortical brain slices, acting via CB1 receptors. The present work demonstrates that although Delta9-THC (1 microM) significantly depressed evoked depolarizing postsynaptic potentials (PSPs) in rat olfactory cortex neurones, both SCE and Delta9-THC-free SCE significantly potentiated evoked PSPs (all results were fully reversed by the CB1 receptor antagonist SR141716A, 1 microM); interestingly, the potentiation by Delta9-THC-free SCE was greater than that produced by SCE. On comparing the effects of Delta9-THC-free SCE upon evoked PSPs and artificial PSPs (aPSPs; evoked electrotonically following brief intracellular current injection), PSPs were enhanced, whereas aPSPs were unaffected, suggesting that the effect was not due to changes in background input resistance. Similar recordings made using CB1 receptor-deficient knockout mice (CB1-/-) and wild-type littermate controls revealed cannabinoid or extract-induced changes in membrane resistance, cell excitability and synaptic transmission in wild-type mice that were similar to those seen in rat neurones, but no effect on these properties were seen in CB1-/- cells. It appears that the unknown extract constituent(s) effects over-rode the suppressive effects of Delta9-THC on excitatory neurotransmitter release, which may explain some patients' preference for herbal cannabis rather than isolated Delta9-THC (due to attenuation of some of the central Delta9-THC side effects) and possibly account for the rare incidence of seizures in some individuals taking cannabis recreationally.

Bat flies (Diptera: Nycteribiidae and Streblidae) infesting cave-dwelling bats in Gabon: diversity, dynamics and potential role in Polychromophilus melanipherus transmission.

PubMed

Obame-Nkoghe, Judicaël; Rahola, Nil; Bourgarel, Mathieu; Yangari, Patrick; Prugnolle, Franck; Maganga, Gael Darren; Leroy, Eric-Maurice; Fontenille, Didier; Ayala, Diego; Paupy, Christophe

2016-06-10

Evidence of haemosporidian infections in bats and bat flies has motivated a growing interest in characterizing their transmission cycles. In Gabon (Central Africa), many caves house massive colonies of bats that are known hosts of Polychromophilus Dionisi parasites, presumably transmitted by blood-sucking bat flies. However, the role of bat flies in bat malaria transmission remains under-documented. An entomological survey was carried out in four caves in Gabon to investigate bat fly diversity, infestation rates and host preferences and to determine their role in Polychromophilus parasite transmission. Bat flies were sampled for 2-4 consecutive nights each month from February to April 2011 (Faucon and Zadie caves) and from May 2012 to April 2013 (Kessipoughou and Djibilong caves). Bat flies isolated from the fur of each captured bat were morphologically identified and screened for infection by haemosporidian parasites using primers targeting the mitochondrial cytochrome b gene. Among the 1,154 bats captured and identified as Miniopterus inflatus Thomas (n = 354), Hipposideros caffer Sundevall complex (n = 285), Hipposideros gigas Wagner (n = 317), Rousettus aegyptiacus Geoffroy (n = 157, and Coleura afra Peters (n = 41), 439 (38.0 %) were infested by bat flies. The 1,063 bat flies recovered from bats belonged to five taxa: Nycteribia schmidlii scotti Falcoz, Eucampsipoda africana Theodor, Penicillidia fulvida Bigot, Brachytarsina allaudi Falcoz and Raymondia huberi Frauenfeld group. The mean infestation rate varied significantly according to the bat species (ANOVA, F (4,75) = 13.15, P < 0.001) and a strong association effect between bat fly species and host bat species was observed. Polychromophilus melanipherus Dionisi was mainly detected in N. s. scotti and P. fulvida and less frequently in E. africana, R. huberi group and B. allaudi bat flies. These results suggest that N. s. scotti and P. fulvida could potentially be involved in P

Predicting optimal transmission investment in malaria parasites.

PubMed

Greischar, Megan A; Mideo, Nicole; Read, Andrew F; Bjørnstad, Ottar N

2016-07-01

In vertebrate hosts, malaria parasites face a tradeoff between replicating and the production of transmission stages that can be passed onto mosquitoes. This tradeoff is analogous to growth-reproduction tradeoffs in multicellular organisms. We use a mathematical model tailored to the life cycle and dynamics of malaria parasites to identify allocation strategies that maximize cumulative transmission potential to mosquitoes. We show that plastic strategies can substantially outperform fixed allocation because parasites can achieve greater fitness by investing in proliferation early and delaying the production of transmission stages. Parasites should further benefit from restraining transmission investment later in infection, because such a strategy can help maintain parasite numbers in the face of resource depletion. Early allocation decisions are predicted to have the greatest impact on parasite fitness. If the immune response saturates as parasite numbers increase, parasites should benefit from even longer delays prior to transmission investment. The presence of a competing strain selects for consistently lower levels of transmission investment and dramatically increased exploitation of the red blood cell resource. While we provide a detailed analysis of tradeoffs pertaining to malaria life history, our approach for identifying optimal plastic allocation strategies may be broadly applicable. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Quasioptical devices based on extraordinary transmission at THz

NASA Astrophysics Data System (ADS)

Beruete, Miguel

2016-04-01

In this work I will present our latest advances in components developed from extraordinary transmission concepts operating at terahertz (THz) frequencies. First, a structure exhibiting two different extraordinary transmission resonances depending on the polarization of the incident wave will be shown. The peaks of transmission appear at approximately 2 and 2.5 THz for vertical and horizontal polarization, respectively, with a transmittance above 60% in both cases. Later on, a meandering line structure able to tune the extraordinary transmission resonance will be discussed. The operation frequency in this case is between 9 and 17 THz. A self-complementary polarizer will be then presented, with a high polarization purity. The fundamentals of this device based on the Babinet's principle will be discussed in depth. Finally, all these structures will be combined together to produce a dual-band Quarter Wave Plate able to convert a linear polarization at the input in a circular polarization at the output at two different bands, 1 and 2.2. THz. Some final words regarding the potential of extraordinary transmission for sensing applications will close the contribution.

A second transmissible cancer in Tasmanian devils

PubMed Central

Pye, Ruth J.; Pemberton, David; Tovar, Cesar; Tubio, Jose M. C.; Dun, Karen A.; Fox, Samantha; Darby, Jocelyn; Hayes, Dane; Knowles, Graeme W.; Kreiss, Alexandre; Siddle, Hannah V. T.; Swift, Kate; Lyons, A. Bruce; Murchison, Elizabeth P.; Woods, Gregory M.

2016-01-01

Clonally transmissible cancers are somatic cell lineages that are spread between individuals via the transfer of living cancer cells. There are only three known naturally occurring transmissible cancers, and these affect dogs, soft-shell clams, and Tasmanian devils, respectively. The Tasmanian devil transmissible facial cancer was first observed in 1996, and is threatening its host species with extinction. Until now, this disease has been consistently associated with a single aneuploid cancer cell lineage that we refer to as DFT1. Here we describe a second transmissible cancer, DFT2, in five devils located in southern Tasmania in 2014 and 2015. DFT2 causes facial tumors that are grossly indistinguishable but histologically distinct from those caused by DFT1. DFT2 bears no detectable cytogenetic similarity to DFT1 and carries a Y chromosome, which contrasts with the female origin of DFT1. DFT2 shows different alleles to both its hosts and DFT1 at microsatellite, structural variant, and major histocompatibility complex (MHC) loci, confirming that it is a second cancer that can be transmitted between devils as an allogeneic, MHC-discordant graft. These findings indicate that Tasmanian devils have spawned at least two distinct transmissible cancer lineages and suggest that transmissible cancers may arise more frequently in nature than previously considered. The discovery of DFT2 presents important challenges for the conservation of Tasmanian devils and raises the possibility that this species is particularly prone to the emergence of transmissible cancers. More generally, our findings highlight the potential for cancer cells to depart from their hosts and become dangerous transmissible pathogens. PMID:26711993

Pathogens at the livestock-wildlife interface in Western Alberta: does transmission route matter?

PubMed Central

2014-01-01

In southwestern Alberta, interactions between beef cattle and free-ranging elk (Cervus elaphus) may provide opportunities for pathogen transmission. To assess the importance of the transmission route on the potential for interspecies transmission, we conducted a cross-sectional study on four endemic livestock pathogens with three different transmission routes: Bovine Viral Diarrhea Virus and Bovine Herpesvirus 1 (predominantly direct transmission), Mycobacterium avium subsp. paratuberculosis (MAP) (indirect fecal-oral transmission), Neospora caninum (indirect transmission with definitive host). We assessed the occurrence of these pathogens in 28 cow-calf operations exposed or non-exposed to elk, and in 10 elk herds exposed or not to cattle. We characterized the effect of species commingling as a risk factor of pathogen exposure and documented the perceived risk of pathogen transmission at this wildlife-livestock interface in the rural community. Herpesviruses found in elk were elk-specific gamma-herpesviruses unrelated to cattle viruses. Pestivirus exposure in elk could not be ascertained to be of livestock origin. Evidence of MAP circulation was found in both elk and cattle, but there was no statistical effect of the species commingling. Finally, N. caninum was more frequently detected in elk exposed to cattle and this association was still significant after adjustment for herd and sampling year clustering, and individual elk age and sex. Only indirectly transmitted pathogens co-occurred in cattle and elk, indicating the potential importance of the transmission route in assessing the risk of pathogen transmission in multi-species grazing systems. PMID:24517283

Small passenger car transmission test: Dodge Omni A-404 transmission

NASA Technical Reports Server (NTRS)

Bujold, M. P.

1980-01-01

The small passenger car transmission test was initiated to supply electric vehicle manufacturers with technical information regarding the performance of commercially available transmissions. This transmission was tested in accordance with a passenger car automatic transmission test code (SAE J65lb) which required drive performance, coast performance, and no load test conditions. Under these test conditions, the transmission attained maximum efficiencies in the mid eighty percent range for both drive performance test and coast performance tests.

Asymmetric scattering by non-Hermitian potentials

NASA Astrophysics Data System (ADS)

Ruschhaupt, A.; Dowdall, T.; Simón, M. A.; Muga, J. G.

2017-10-01

The scattering of quantum particles by non-Hermitian (generally non-local) potentials in one dimension may result in asymmetric transmission and/or reflection from left and right incidence. After extending the concept of symmetry for non-Hermitian potentials, eight generalized symmetries based on the discrete Klein's four-group (formed by parity, time reversal, their product, and unity) are found. Together with generalized unitarity relations they determine selection rules for the possible and/or forbidden scattering asymmetries. Six basic device types are identified when the scattering coefficients (squared moduli of scattering amplitudes) adopt zero/one values, and transmission and/or reflection are asymmetric. They can pictorically be described as a one-way mirror, a one-way barrier (a Maxwell pressure demon), one-way (transmission or reflection) filters, a mirror with unidirectional transmission, and a transparent, one-way reflector. We design potentials for these devices and also demonstrate that the behavior of the scattering coefficients can be extended to a broad range of incident momenta.

Expert review on poliovirus immunity and transmission.

PubMed

Duintjer Tebbens, Radboud J; Pallansch, Mark A; Chumakov, Konstantin M; Halsey, Neal A; Hovi, Tapani; Minor, Philip D; Modlin, John F; Patriarca, Peter A; Sutter, Roland W; Wright, Peter F; Wassilak, Steven G F; Cochi, Stephen L; Kim, Jong-Hoon; Thompson, Kimberly M

2013-04-01

Successfully managing risks to achieve wild polioviruses (WPVs) eradication and address the complexities of oral poliovirus vaccine (OPV) cessation to stop all cases of paralytic poliomyelitis depends strongly on our collective understanding of poliovirus immunity and transmission. With increased shifting from OPV to inactivated poliovirus vaccine (IPV), numerous risk management choices motivate the need to understand the tradeoffs and uncertainties and to develop models to help inform decisions. The U.S. Centers for Disease Control and Prevention hosted a meeting of international experts in April 2010 to review the available literature relevant to poliovirus immunity and transmission. This expert review evaluates 66 OPV challenge studies and other evidence to support the development of quantitative models of poliovirus transmission and potential outbreaks. This review focuses on characterization of immunity as a function of exposure history in terms of susceptibility to excretion, duration of excretion, and concentration of excreted virus. We also discuss the evidence of waning of host immunity to poliovirus transmission, the relationship between the concentration of poliovirus excreted and infectiousness, the importance of different transmission routes, and the differences in transmissibility between OPV and WPV. We discuss the limitations of the available evidence for use in polio risk models, and conclude that despite the relatively large number of studies on immunity, very limited data exist to directly support quantification of model inputs related to transmission. Given the limitations in the evidence, we identify the need for expert input to derive quantitative model inputs from the existing data. © 2012 Society for Risk Analysis.

Spatial modelling of the potential temperature-dependent transmission of vector-associated diseases in the face of climate change: main results and recommendations from a pilot study in Lower Saxony (Germany).

PubMed

Schröder, Winfried; Schmidt, Gunther

2008-12-01

The sustained climate change is going to modify the geographic distribution, the seasonal transmission gate and the intensity of the transmission of vector-borne diseases such as malaria or the bluetongue disease. These diseases occur nowadays at higher latitudes or altitudes. A further rise in ambient temperature and rainfall will extend the duration of the season in which mosquito vectors are transmitting pathogens. The parasites transmitted by the vectors also benefit from increasing temperatures, as both their reproduction and development are then accelerated, too. Thus, it seemed prudent to examine potential effects on the seasonal transmission gate due to the ongoing and predicted climate changes. Lower Saxony (northwest Germany) is a former malaria region with highest incidences of Anopheles atroparvus and tertian malaria along the coastal zones before malaria had finally become extinct in the early 1950s. Nevertheless, the Anopheles mosquitoes which transmit the malaria pathogens have still been present in Lower Saxony up to now. This together with the climate change-related implications gave reason to investigate whether a new autochthonous transmission could take place if the malaria pathogen is introduced again in Lower Saxony. Thus, the potential spatial and temporal structure of temperature-driven malaria transmissions was mapped using the basic reproduction rate (R (0)) and measured and predicted air temperatures (1947-1960, 1961-1990, 1985-2004, 2020, 2060, 2100, each best case and worst case scenario). This paper focuses on both the summarizing of the results from this risk modelling approach and on the conclusions to be drawn. The recommendations highlight the need to link vector monitoring as one of the key elements of an epidemiological monitoring with the environmental monitoring.

Potential benefits of long-distance electricity transmission in China for air quality and climate

NASA Astrophysics Data System (ADS)

Peng, W.; Mauzerall, D. L.; Yuan, J.; Zhao, Y.; Lin, M.; Zhang, Q.

2015-12-01

China is expanding west-to-east long-distance electricity transmission capacity with the aim of reducing eastern coal power production and resulting air pollution. In addition to coal power, this new grid capacity can be used to transport renewable-generated electricity with resulting climate co-benefits. Here we use an integrated assessment to evaluate the air quality and climate benefits of twelve proposed transmission lines in China, and compare two energy-by-wire strategies that transmit 1) only coal power (Coal-by-wire, CbW) or 2) combined renewable plus coal power (Renewable and coal-by-wire, (RE+C)bW), with 3) the current practice of transporting coal by rail for conversion to electricity near eastern demand centers (Coal-by-rail, CbR). Based on a regional atmospheric chemistry model, WRF-Chem, electricity transmission through the proposed lines leads to 2-3 μg/m3 (2-7%) reduction in the annual mean concentrations of fine particulate matter (PM2.5) in the eastern provinces relative to 2010 levels, roughly ~1 μg/m3 greater than the reduction achieved in CbR where dirty coal units are locally replaced with efficient ones. Although the eastern air quality improvement is similar irrespective of the fuel source to power the lines, adding coal generation results in up to 3% increase in annual mean PM2.5 levels in some exporting provinces, whereas such increase is not observed when most added capacity is renewable-based. Counting both the economic value of reduced carbon emissions and the health-related air quality benefits can significantly improve the cost-effectiveness of transmitting both renewable and coal power. Comparing (RE+C)bW with the two coal-based options, we find not only 20% larger reduction in air-pollution-related deaths, but also three times greater reduction in CO2 emissions. Our study hence demonstrates the significance of coordinating renewable energy planning with transmission planning to simultaneously tackle air pollution and climate

Low potential for mechanical transmission of Ebola virus via house flies (Musca domestica)

USDA-ARS?s Scientific Manuscript database

Ebola virus emerged in West Africa in March 2014 and has caused more than 28,000 cases and 11,000 deaths. The unusually high number of cases raised the question as to whether muscid flies could mechanically transmit the virus. Mechanical transmission of Ebola virus was attempted using house flies t...

Multiple mechanisms of transmission of the Caribbean coral disease white plague

NASA Astrophysics Data System (ADS)

Clemens, E.; Brandt, M. E.

2015-12-01

White plague is one of the most devastating coral diseases in the Caribbean, and yet important aspects of its epidemiology, including how the disease transmits, remain unknown. This study tested potential mechanisms and rates of transmission of white plague in a laboratory setting. Transmission mechanisms including the transport of water, contact with macroalgae, and predation via corallivorous worms and snails were tested on the host species Orbicella annularis. Two of the tested mechanisms were shown to transmit disease: water transport and the corallivorous snail Coralliophila abbreviata. Between these transmission mechanisms, transport of water between a diseased coral and a healthy coral resulted in disease incidence significantly more frequently in exposed healthy corals. Transmission via water transport also occurred more quickly and was associated with higher rates of tissue loss (up to 3.5 cm d-1) than with the corallivorous snail treatment. In addition, water that was in contact with diseased corals but was filtered with a 0.22-μm filter prior to being introduced to apparently healthy corals also resulted in the transmission of disease signs, but at a much lower rate than when water was not filtered. This study has provided important information on the transmission potential of Caribbean white plague disease and highlights the need for a greater understanding of how these processes operate in the natural environment.

Knowledge transmission model with differing initial transmission and retransmission process

NASA Astrophysics Data System (ADS)

Wang, Haiying; Wang, Jun; Small, Michael

2018-10-01

Knowledge transmission is a cyclic dynamic diffusion process. The rate of acceptance of knowledge differs upon whether or not the recipient has previously held the knowledge. In this paper, the knowledge transmission process is divided into an initial and a retransmission procedure, each with its own transmission and self-learning parameters. Based on epidemic spreading model, we propose a naive-evangelical-agnostic (VEA) knowledge transmission model and derive mean-field equations to describe the dynamics of knowledge transmission in homogeneous networks. Theoretical analysis identifies a criterion for the persistence of knowledge, i.e., the reproduction number R0 depends on the minor effective parameters between the initial and retransmission process. Moreover, the final size of evangelical individuals is only related to retransmission process parameters. Numerical simulations validate the theoretical analysis. Furthermore, the simulations indicate that increasing the initial transmission parameters, including first transmission and self-learning rates of naive individuals, can accelerate the velocity of knowledge transmission efficiently but have no effect on the final size of evangelical individuals. In contrast, the retransmission parameters, including retransmission and self-learning rates of agnostic individuals, have a significant effect on the rate of knowledge transmission, i.e., the larger parameters the greater final density of evangelical individuals.

Ionotropic glutamate receptors contribute to pain transmission and chronic pain.

PubMed

Zhuo, Min

2017-01-01

Investigation of the synaptic mechanisms for sensory transmission and modulation provide us with critical information about the transmission of painful sensation as well as the basic mechanisms of chronic pain. Recent studies consistently demonstrate that glutamatergic synapses not only play an important role in sensory transmission, including pain and itch transmission, but also contribute to nociceptive sensitization at different levels of the brain. Different subtypes of glutamate receptors play selective roles in synaptic transmission and long-term potentiation (LTP), as well as synaptic modulation. Understanding the contribution of each subtype of glutamate receptors, and related downstream signaling pathways may provide a new opportunity to design better medicine for the treatment of different forms of chronic pain. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'. Copyright © 2016 Elsevier Ltd. All rights reserved.

Transmission of climate risks across sectors and borders

NASA Astrophysics Data System (ADS)

Challinor, Andy J.; Adger, W. Neil; Benton, Tim G.; Conway, Declan; Joshi, Manoj; Frame, Dave

2018-06-01

Systemic climate risks, which result from the potential for cascading impacts through inter-related systems, pose particular challenges to risk assessment, especially when risks are transmitted across sectors and international boundaries. Most impacts of climate variability and change affect regions and jurisdictions in complex ways, and techniques for assessing this transmission of risk are still somewhat limited. Here, we begin to define new approaches to risk assessment that can account for transboundary and trans-sector risk transmission, by presenting: (i) a typology of risk transmission that distinguishes clearly the role of climate versus the role of the social and economic systems that distribute resources; (ii) a review of existing modelling, qualitative and systems-based methods of assessing risk and risk transmission; and (iii) case studies that examine risk transmission in human displacement, food, water and energy security. The case studies show that policies and institutions can attenuate risks significantly through cooperation that can be mutually beneficial to all parties. We conclude with some suggestions for assessment of complex risk transmission mechanisms: use of expert judgement; interactive scenario building; global systems science and big data; innovative use of climate and integrated assessment models; and methods to understand societal responses to climate risk. These approaches aim to inform both research and national-level risk assessment.

Small passenger car transmission test; Ford C4 transmission

NASA Technical Reports Server (NTRS)

Bujold, M. P.

1980-01-01

A 1979 Ford C4 automatic transmission was tested per a passenger car automatic transmission test code (SAE J651b) which required drive performance, coast performance, and no load test conditions. Under these test conditions, the transmission attained maximum efficiencies in the mid-eighty percent range for both drive performance tests and coast performance tests. The major results of this test (torque, speed, and efficiency curves) are presented. Graphs map the complete performance characteristics for the Ford C4 transmission.

What was the primary mode of smallpox transmission? Implications for biodefense

PubMed Central

Milton, Donald K.

2012-01-01

The mode of infection transmission has profound implications for effective containment by public health interventions. The mode of smallpox transmission was never conclusively established. Although, “respiratory droplet” transmission was generally regarded as the primary mode of transmission, the relative importance of large ballistic droplets and fine particle aerosols that remain suspended in air for more than a few seconds was never resolved. This review examines evidence from the history of variolation, data on mucosal infection collected in the last decades of smallpox transmission, aerosol measurements, animal models, reports of smallpox lung among healthcare workers, and the epidemiology of smallpox regarding the potential importance of fine particle aerosol mediated transmission. I introduce briefly the term anisotropic infection to describe the behavior of Variola major in which route of infection appears to have altered the severity of disease. PMID:23226686

Evidence for carry-over effects of predator exposure on pathogen transmission potential.

PubMed

Roux, Olivier; Vantaux, Amélie; Roche, Benjamin; Yameogo, Koudraogo B; Dabiré, Kounbobr R; Diabaté, Abdoulaye; Simard, Frederic; Lefèvre, Thierry

2015-12-22

Accumulating evidence indicates that species interactions such as competition and predation can indirectly alter interactions with other community members, including parasites. For example, presence of predators can induce behavioural defences in the prey, resulting in a change in susceptibility to parasites. Such predator-induced phenotypic changes may be especially pervasive in prey with discrete larval and adult stages, for which exposure to predators during larval development can have strong carry-over effects on adult phenotypes. To the best of our knowledge, no study to date has examined possible carry-over effects of predator exposure on pathogen transmission. We addressed this question using a natural food web consisting of the human malaria parasite Plasmodium falciparum, the mosquito vector Anopheles coluzzii and a backswimmer, an aquatic predator of mosquito larvae. Although predator exposure did not significantly alter mosquito susceptibility to P. falciparum, it incurred strong fitness costs on other key mosquito life-history traits, including larval development, adult size, fecundity and longevity. Using an epidemiological model, we show that larval predator exposure should overall significantly decrease malaria transmission. These results highlight the importance of taking into account the effect of environmental stressors on disease ecology and epidemiology. © 2015 The Author(s).

Transmission Dynamics of the Four Dengue Serotypes in Southern Vietnam and the Potential Impact of Vaccination

PubMed Central

Coudeville, Laurent; Garnett, Geoff P.

2012-01-01

Background With approximately 2.5 billion people at risk, dengue is a major international public health concern. Dengue vaccines currently in development should help reduce the burden associated with this disease but the most efficient way of using future dengue vaccines remains to be defined. Mathematical models of transmission can provide insight into the expected impact of different vaccination strategies at a population level and contribute to this definition. Methods and Findings We developed and analyzed an age-structured, host-vector and serotype-specific compartmental model, including seasonality. We first used this transmission model to identify the immunological interactions between serotypes that affect the risks and consequences of secondary infections (cross-protection, increased susceptibility, increased severity, and increased infectiousness) and reproduce the observed epidemiology of dengue. For populating this model, we used routine surveillance data from Southern Vietnam and the results of a prospective cohort study conducted in the same area. The model provided a good fit to the observed data for age, severity of cases, serotype distribution, and dynamics over time, using two scenarios of immunological interaction : short term cross-protection alone (6–17 months) or a combination of short term cross-protection with cross-enhancement (increased susceptibility, severity and infectiousness in the case of secondary infections). Finally, we explored the potential impact of vaccination for these two scenarios. Both highlighted that vaccination can substantially decrease dengue burden by reducing the magnitude and frequency of outbreaks. Conclusion Our model suggests that seasonality and short term cross-protection are key factors for explaining dengue dynamics in Southern Vietnam. Vaccination was predicted to significantly reduce the disease burden, even in the situation where immunological cross-enhancement affects the risks and consequences of

Quantifying Transmission.

PubMed

Woolhouse, Mark

2017-07-01

Transmissibility is the defining characteristic of infectious diseases. Quantifying transmission matters for understanding infectious disease epidemiology and designing evidence-based disease control programs. Tracing individual transmission events can be achieved by epidemiological investigation coupled with pathogen typing or genome sequencing. Individual infectiousness can be estimated by measuring pathogen loads, but few studies have directly estimated the ability of infected hosts to transmit to uninfected hosts. Individuals' opportunities to transmit infection are dependent on behavioral and other risk factors relevant given the transmission route of the pathogen concerned. Transmission at the population level can be quantified through knowledge of risk factors in the population or phylogeographic analysis of pathogen sequence data. Mathematical model-based approaches require estimation of the per capita transmission rate and basic reproduction number, obtained by fitting models to case data and/or analysis of pathogen sequence data. Heterogeneities in infectiousness, contact behavior, and susceptibility can have substantial effects on the epidemiology of an infectious disease, so estimates of only mean values may be insufficient. For some pathogens, super-shedders (infected individuals who are highly infectious) and super-spreaders (individuals with more opportunities to transmit infection) may be important. Future work on quantifying transmission should involve integrated analyses of multiple data sources.

Possible impacts of sea level rise on disease transmission and potential adaptation strategies, a review.

PubMed

Dvorak, Ana C; Solo-Gabriele, Helena M; Galletti, Andrea; Benzecry, Bernardo; Malone, Hannah; Boguszewski, Vicki; Bird, Jason

2018-07-01

Sea levels are projected to rise in response to climate change, causing the intrusion of sea water into land. In flat coastal regions, this would generate an increase in shallow water covered areas with limited circulation. This scenario raises a concern about the consequences it could have on human health, specifically the possible impacts on disease transmission. In this review paper we identified three categories of diseases which are associated with water and whose transmission can be affected by sea level rise. These categories include: mosquitoborne diseases, naturalized organisms (Vibrio spp. and toxic algae), and fecal-oral diseases. For each disease category, we propose comprehensive adaptation strategies that would help minimize possible health risks. Finally, the City of Key West, Florida is analyzed as a case study, due to its inherent vulnerability to sea level rise. Current and projected adaptation techniques are discussed as well as the integration of additional recommendations, focused on disease transmission control. Given that sea level rise will likely continue into the future, the promotion and implementation of positive adaptation strategies is necessary to ensure community resilience. Copyright © 2018 Elsevier Ltd. All rights reserved.

Flux Cloning in Josephson Transmission Lines

NASA Astrophysics Data System (ADS)

Gulevich, D. R.; Kusmartsev, F. V.

2006-07-01

We describe a novel effect related to the controlled birth of a single Josephson vortex. In this phenomenon, the vortex is created in a Josephson transmission line at a T-shaped junction. The “baby” vortex arises at the moment when a “mother” vortex propagating in the adjacent transmission line passes the T-shaped junction. In order to give birth to a new vortex, the mother vortex must have enough kinetic energy. Its motion can also be supported by an externally applied driving current. We determine the critical velocity and the critical driving current for the creation of the baby vortices and briefly discuss the potential applications of the found effect.

Environmental, entomological, socioeconomic and behavioural risk factors for malaria attacks in Amerindian children of Camopi, French Guiana

PubMed Central

2011-01-01

Background Malaria is a major health issue in French Guiana. Amerindian communities remain the most affected. A previous study in Camopi highlighted the predominant role of environmental factors in the occurrence of malaria. However, all parameters involved in the transmission were not clearly identified. A new survey was conducted in order to clarify the risk factors for the presence of malaria cases in Camopi. Methods An open cohort of children under seven years of age was set up on the basis of biologically confirmed malaria cases for the period 2001-2009. Epidemiological and observational environmental data were collected using two structured questionnaires. Data were analysed with a multiple failures multivariate Cox model. The influence of climate and the river level on malaria incidence was evaluated by time-series analysis. Relationships between Anopheles darlingi human biting rates and malaria incidence rates were estimated using Spearman's rank correlation. Results The global annual incidence over the nine-year period was 238 per 1,000 for Plasmodium falciparum, 514 per 1,000 for Plasmodium visa and 21 per 1,000 for mixed infections. The multivariate survival analysis associated higher malaria incidence with living on the Camopi riverside vs. the Oyapock riverside, far from the centre of the Camopi hamlet, in a home with numerous occupants and going to sleep late. On the contrary, living in a house cleared of all vegetation within 50 m and at high distance of the forest were associated with a lower risk. Meteorological and hydrological characteristics appeared to be correlated with malaria incidence with different lags. Anopheles darlingi human biting rate was also positively correlated to incident malaria in children one month later. Conclusions Malaria incidence in children remains high in young children despite the appearance of immunity in children around three years of age. The closeness environment but also the meteorological parameters play an

Estimating household and community transmission of ocular Chlamydia trachomatis.

PubMed

Blake, Isobel M; Burton, Matthew J; Bailey, Robin L; Solomon, Anthony W; West, Sheila; Muñoz, Beatriz; Holland, Martin J; Mabey, David C W; Gambhir, Manoj; Basáñez, María-Gloria; Grassly, Nicholas C

2009-01-01

Community-wide administration of antibiotics is one arm of a four-pronged strategy in the global initiative to eliminate blindness due to trachoma. The potential impact of more efficient, targeted treatment of infected households depends on the relative contribution of community and household transmission of infection, which have not previously been estimated. A mathematical model of the household transmission of ocular Chlamydia trachomatis was fit to detailed demographic and prevalence data from four endemic populations in The Gambia and Tanzania. Maximum likelihood estimates of the household and community transmission coefficients were obtained. The estimated household transmission coefficient exceeded both the community transmission coefficient and the rate of clearance of infection by individuals in three of the four populations, allowing persistent transmission of infection within households. In all populations, individuals in larger households contributed more to the incidence of infection than those in smaller households. Transmission of ocular C. trachomatis infection within households is typically very efficient. Failure to treat all infected members of a household during mass administration of antibiotics is likely to result in rapid re-infection of that household, followed by more gradual spread across the community. The feasibility and effectiveness of household targeted strategies should be explored.

Transmission dynamics and elimination potential of zoonotic tuberculosis in morocco

PubMed Central

Justus Bless, Philipp; Crump, Lisa; Lohmann, Petra; Laager, Mirjam; Chitnis, Nakul; Zinsstag, Jakob

2017-01-01

Bovine tuberculosis (BTB) is an endemic zoonosis in Morocco caused by Mycobacterium bovis, which infects many domestic animals and is transmitted to humans through consumption of raw milk or from contact with infected animals. The prevalence of BTB in Moroccan cattle is estimated at 18%, and 33% at the individual and the herd level respectively, but the human M. bovis burden needs further clarification. The current control strategy based on test and slaughter should be improved through local context adaptation taking into account a suitable compensation in order to reduce BTB prevalence in Morocco and decrease the disease burden in humans and animals. We established a simple compartmental deterministic mathematical model for BTB transmission in cattle and humans to provide a general understanding of BTB, in particular regarding transmission to humans. Differential equations were used to model the different pathways between the compartments for cattle and humans. Scenarios of test and slaughter were simulated to determine the effects of varying the proportion of tested animals (p) on the time to elimination of BTB (individual animal prevalence of less than one in a thousand) in cattle and humans. The time to freedom from disease ranged from 75 years for p = 20% to 12 years for p = 100%. For p > 60% the time to elimination was less than 20 years. The cumulated cost was largely stable: for p values higher than 40%, cost ranged from 1.47 to 1.60 billion euros with a time frame of 12 to 32 years to reach freedom from disease. The model simulations also suggest that using a 2mm cut off instead of a 4mm cut off in the Single Intradermal Comparative Cervical Tuberculin skin test (SICCT) would result in cheaper and quicker elimination programs. This analysis informs Moroccan bovine tuberculosis control policy regarding time frame, range of cost and levels of intervention. However, further research is needed to clarify the national human-bovine tuberculosis ratio in Morocco

Transmission dynamics and elimination potential of zoonotic tuberculosis in morocco.

PubMed

Abakar, Mahamat Fayiz; Yahyaoui Azami, Hind; Justus Bless, Philipp; Crump, Lisa; Lohmann, Petra; Laager, Mirjam; Chitnis, Nakul; Zinsstag, Jakob

2017-02-01

Bovine tuberculosis (BTB) is an endemic zoonosis in Morocco caused by Mycobacterium bovis, which infects many domestic animals and is transmitted to humans through consumption of raw milk or from contact with infected animals. The prevalence of BTB in Moroccan cattle is estimated at 18%, and 33% at the individual and the herd level respectively, but the human M. bovis burden needs further clarification. The current control strategy based on test and slaughter should be improved through local context adaptation taking into account a suitable compensation in order to reduce BTB prevalence in Morocco and decrease the disease burden in humans and animals. We established a simple compartmental deterministic mathematical model for BTB transmission in cattle and humans to provide a general understanding of BTB, in particular regarding transmission to humans. Differential equations were used to model the different pathways between the compartments for cattle and humans. Scenarios of test and slaughter were simulated to determine the effects of varying the proportion of tested animals (p) on the time to elimination of BTB (individual animal prevalence of less than one in a thousand) in cattle and humans. The time to freedom from disease ranged from 75 years for p = 20% to 12 years for p = 100%. For p > 60% the time to elimination was less than 20 years. The cumulated cost was largely stable: for p values higher than 40%, cost ranged from 1.47 to 1.60 billion euros with a time frame of 12 to 32 years to reach freedom from disease. The model simulations also suggest that using a 2mm cut off instead of a 4mm cut off in the Single Intradermal Comparative Cervical Tuberculin skin test (SICCT) would result in cheaper and quicker elimination programs. This analysis informs Moroccan bovine tuberculosis control policy regarding time frame, range of cost and levels of intervention. However, further research is needed to clarify the national human-bovine tuberculosis ratio in Morocco.

Bayesian reconstruction of transmission within outbreaks using genomic variants.

PubMed

De Maio, Nicola; Worby, Colin J; Wilson, Daniel J; Stoesser, Nicole

2018-04-01

Pathogen genome sequencing can reveal details of transmission histories and is a powerful tool in the fight against infectious disease. In particular, within-host pathogen genomic variants identified through heterozygous nucleotide base calls are a potential source of information to identify linked cases and infer direction and time of transmission. However, using such data effectively to model disease transmission presents a number of challenges, including differentiating genuine variants from those observed due to sequencing error, as well as the specification of a realistic model for within-host pathogen population dynamics. Here we propose a new Bayesian approach to transmission inference, BadTrIP (BAyesian epiDemiological TRansmission Inference from Polymorphisms), that explicitly models evolution of pathogen populations in an outbreak, transmission (including transmission bottlenecks), and sequencing error. BadTrIP enables the inference of host-to-host transmission from pathogen sequencing data and epidemiological data. By assuming that genomic variants are unlinked, our method does not require the computationally intensive and unreliable reconstruction of individual haplotypes. Using simulations we show that BadTrIP is robust in most scenarios and can accurately infer transmission events by efficiently combining information from genetic and epidemiological sources; thanks to its realistic model of pathogen evolution and the inclusion of epidemiological data, BadTrIP is also more accurate than existing approaches. BadTrIP is distributed as an open source package (https://bitbucket.org/nicofmay/badtrip) for the phylogenetic software BEAST2. We apply our method to reconstruct transmission history at the early stages of the 2014 Ebola outbreak, showcasing the power of within-host genomic variants to reconstruct transmission events.

Wireless OAM transmission system based on elliptical microstrip patch antenna.

PubMed

Chen, Jia Jia; Lu, Qian Nan; Dong, Fei Fei; Yang, Jing Jing; Huang, Ming

2016-05-30

The multiplexing transmission has always been a focus of attention for communication technology. In this paper, the radiation characteristics of circular microstrip patch antenna was firstly analyzed based on cavity model theory, and then spiral beams carrying orbital angular momentum (OAM) were generated, using elliptical microstrip patch antenna, with a single feed probe instead of a standard circular patch with two feedpoints. Moreover, by combining the proposed elliptic microstrip patch antenna with Universal Software Radio Peripheral (USRP), a wireless OAM transmission system was established and the real-time transmission of text, image and video in a real channel environment was realized. Since the wireless OAM transmission has the advantage of good safety and high spectrum utilization efficiency, this work has theoretical significance and potential application.

Clostridium difficile infection: epidemiology, diagnosis and understanding transmission.

PubMed

Martin, Jessica S H; Monaghan, Tanya M; Wilcox, Mark H

2016-04-01

Clostridium difficile infection (CDI) continues to affect patients in hospitals and communities worldwide. The spectrum of clinical disease ranges from mild diarrhoea to toxic megacolon, colonic perforation and death. However, this bacterium might also be carried asymptomatically in the gut, potentially leading to 'silent' onward transmission. Modern technologies, such as whole-genome sequencing and multi-locus variable-number tandem-repeat analysis, are helping to track C. difficile transmission across health-care facilities, countries and continents, offering the potential to illuminate previously under-recognized sources of infection. These typing strategies have also demonstrated heterogeneity in terms of CDI incidence and strain types reflecting different stages of epidemic spread. However, comparison of CDI epidemiology, particularly between countries, is challenging due to wide-ranging approaches to sampling and testing. Diagnostic strategies for C. difficile are complicated both by the wide range of bacterial targets and tests available and the need to differentiate between toxin-producing and non-toxigenic strains. Multistep diagnostic algorithms have been recommended to improve sensitivity and specificity. In this Review, we describe the latest advances in the understanding of C. difficile epidemiology, transmission and diagnosis, and discuss the effect of these developments on the clinical management of CDI.

Patient-to-patient transmission of hepatitis C virus (HCV) during colonoscopy diagnosis

PubMed Central

2010-01-01

Background No recognized risk factors can be identified in 10-40% of hepatitis C virus (HCV)-infected patients suggesting that the modes of transmission involved could be underestimated or unidentified. Invasive diagnostic procedures, such as endoscopy, have been considered as a potential HCV transmission route; although the actual extent of transmission in endoscopy procedures remains controversial. Most reported HCV outbreaks related to nosocomial acquisition have been attributed to unsafe injection practices and use of multi-dose vials. Only a few cases of likely patient-to-patient HCV transmission via a contaminated colonoscope have been reported to date. Nosocomial HCV infection may have important medical and legal implications and, therefore, possible transmission routes should be investigated. In this study, a case of nosocomial transmission of HCV from a common source to two patients who underwent colonoscopy in an endoscopy unit is reported. Results A retrospective epidemiological search after detection of index cases revealed several potentially infective procedures: sample blood collection, use of a peripheral catheter, anesthesia and colonoscopy procedures. The epidemiological investigation showed breaches in colonoscope reprocessing and deficiencies in the recording of valuable tracing data. Direct sequences from the NS5B region were obtained to determine the extent of the outbreak and cloned sequences from the E1-E2 region were used to establish the relationships among intrapatient viral populations. Phylogenetic analyses of individual sequences from viral populations infecting the three patients involved in the outbreak confirmed the patient pointed out by the epidemiological search as the source of the outbreak. Furthermore, the sequential order in which the patients underwent colonoscopy correlates with viral genetic variability estimates. Conclusions Patient-to-patient transmission of HCV could be demonstrated although the precise route of

Leishmune vaccine: the newest tool for prevention and control of canine visceral leishmaniosis and its potential as a transmission-blocking vaccine.

PubMed

Dantas-Torres, Filipe

2006-10-10

Canine visceral leishmaniosis is a life-threatening disease caused by Leishmania infantum. For quite some time, specialists in leishmaniosis have tried to develop more affordable and effective control measures against this disease. In this search, the first vaccine against canine visceral leishmaniosis was recently licensed in Brazil. In the light of recent research, the Leishmune vaccine might be seen as the newest tool for prevention and control of canine visceral leishmaniosis. Moreover, the potential of the Leishmune as a transmission-blocking vaccine has recently been demonstrated, indicating its usefulness in the control of zoonotic visceral leishmaniosis.

Research on UAV Intelligent Obstacle Avoidance Technology During Inspection of Transmission Line

NASA Astrophysics Data System (ADS)

Wei, Chuanhu; Zhang, Fei; Yin, Chaoyuan; Liu, Yue; Liu, Liang; Li, Zongyu; Wang, Wanguo

Autonomous obstacle avoidance of unmanned aerial vehicle (hereinafter referred to as UAV) in electric power line inspection process has important significance for operation safety and economy for UAV intelligent inspection system of transmission line as main content of UAV intelligent inspection system on transmission line. In the paper, principles of UAV inspection obstacle avoidance technology of transmission line are introduced. UAV inspection obstacle avoidance technology based on particle swarm global optimization algorithm is proposed after common obstacle avoidance technologies are studied. Stimulation comparison is implemented with traditional UAV inspection obstacle avoidance technology which adopts artificial potential field method. Results show that UAV inspection strategy of particle swarm optimization algorithm, adopted in the paper, is prominently better than UAV inspection strategy of artificial potential field method in the aspects of obstacle avoidance effect and the ability of returning to preset inspection track after passing through the obstacle. An effective method is provided for UAV inspection obstacle avoidance of transmission line.

Transmission of scrapie prions to primate after an extended silent incubation period.

PubMed

Comoy, Emmanuel E; Mikol, Jacqueline; Luccantoni-Freire, Sophie; Correia, Evelyne; Lescoutra-Etchegaray, Nathalie; Durand, Valérie; Dehen, Capucine; Andreoletti, Olivier; Casalone, Cristina; Richt, Juergen A; Greenlee, Justin J; Baron, Thierry; Benestad, Sylvie L; Brown, Paul; Deslys, Jean-Philippe

2015-06-30

Classical bovine spongiform encephalopathy (c-BSE) is the only animal prion disease reputed to be zoonotic, causing variant Creutzfeldt-Jakob disease (vCJD) in humans and having guided protective measures for animal and human health against animal prion diseases. Recently, partial transmissions to humanized mice showed that the zoonotic potential of scrapie might be similar to c-BSE. We here report the direct transmission of a natural classical scrapie isolate to cynomolgus macaque, a highly relevant model for human prion diseases, after a 10-year silent incubation period, with features similar to those reported for human cases of sporadic CJD. Scrapie is thus actually transmissible to primates with incubation periods compatible with their life expectancy, although fourfold longer than BSE. Long-term experimental transmission studies are necessary to better assess the zoonotic potential of other prion diseases with high prevalence, notably Chronic Wasting Disease of deer and elk and atypical/Nor98 scrapie.

Transmission of scrapie prions to primate after an extended silent incubation period

PubMed Central

Comoy, Emmanuel E.; Mikol, Jacqueline; Luccantoni-Freire, Sophie; Correia, Evelyne; Lescoutra-Etchegaray, Nathalie; Durand, Valérie; Dehen, Capucine; Andreoletti, Olivier; Casalone, Cristina; Richt, Juergen A.; Greenlee, Justin J.; Baron, Thierry; Benestad, Sylvie L.; Brown, Paul; Deslys, Jean-Philippe

2015-01-01

Classical bovine spongiform encephalopathy (c-BSE) is the only animal prion disease reputed to be zoonotic, causing variant Creutzfeldt-Jakob disease (vCJD) in humans and having guided protective measures for animal and human health against animal prion diseases. Recently, partial transmissions to humanized mice showed that the zoonotic potential of scrapie might be similar to c-BSE. We here report the direct transmission of a natural classical scrapie isolate to cynomolgus macaque, a highly relevant model for human prion diseases, after a 10-year silent incubation period, with features similar to those reported for human cases of sporadic CJD. Scrapie is thus actually transmissible to primates with incubation periods compatible with their life expectancy, although fourfold longer than BSE. Long-term experimental transmission studies are necessary to better assess the zoonotic potential of other prion diseases with high prevalence, notably Chronic Wasting Disease of deer and elk and atypical/Nor98 scrapie. PMID:26123044

Potential for broad-scale transmission of Ebola virus disease during the West Africa crisis: lessons for the Global Health security agenda.

PubMed

Undurraga, Eduardo A; Carias, Cristina; Meltzer, Martin I; Kahn, Emily B

2017-12-01

The 2014-2016 Ebola crisis in West Africa had approximately eight times as many reported deaths as the sum of all previous Ebola outbreaks. The outbreak magnitude and occurrence of multiple Ebola cases in at least seven countries beyond Liberia, Sierra Leone, and Guinea, hinted at the possibility of broad-scale transmission of Ebola. Using a modeling tool developed by the US Centers for Disease Control and Prevention during the Ebola outbreak, we estimated the number of Ebola cases that might have occurred had the disease spread beyond the three countries in West Africa to cities in other countries at high risk for disease transmission (based on late 2014 air travel patterns). We estimated Ebola cases in three scenarios: a delayed response, a Liberia-like response, and a fast response scenario. Based on our estimates of the number of Ebola cases that could have occurred had Ebola spread to other countries beyond the West African foci, we emphasize the need for improved levels of preparedness and response to public health threats, which is the goal of the Global Health Security Agenda. Our estimates suggest that Ebola could have potentially spread widely beyond the West Africa foci, had local and international health workers and organizations not committed to a major response effort. Our results underscore the importance of rapid detection and initiation of an effective, organized response, and the challenges faced by countries with limited public health systems. Actionable lessons for strengthening local public health systems in countries at high risk of disease transmission include increasing health personnel, bolstering primary and critical healthcare facilities, developing public health infrastructure (e.g. laboratory capacity), and improving disease surveillance. With stronger local public health systems infectious disease outbreaks would still occur, but their rapid escalation would be considerably less likely, minimizing the impact of public health threats

Sheath energy transmission in a collisional plasma with collisionless sheath

DOE PAGES

Tang, Xian-Zhu; Guo, Zehua

2015-10-16

Sheath energy transmission governs the plasma energy exhaust onto a material surface. The ion channel is dominated by convection, but the electron channel has a significant thermal conduction component, which is dominated by the Knudsen layer effect in the presence of an absorbing wall. First-principle kinetic simulations also reveal a robustly supersonic sheath entry flow. The ion sheath energy transmission and the sheath potential are accurately predicted by a sheath model of truncated bi-Maxwellian electron distribution. The electron energy transmission is further enhanced by a parallel heat flux of the perpendicular degrees of freedom.

Ecologic Niche Modeling and Spatial Patterns of Disease Transmission

PubMed Central

2006-01-01

Ecologic niche modeling (ENM) is a growing field with many potential applications to questions regarding the geography and ecology of disease transmission. Specifically, ENM has the potential to inform investigations concerned with the geography, or potential geography, of vectors, hosts, pathogens, or human cases, and it can achieve fine spatial resolution without the loss of information inherent in many other techniques. Potential applications and current frontiers and challenges are reviewed. PMID:17326931

Cloud Properties Derived from Surface-Based Near-Infrared Spectral Transmission

NASA Technical Reports Server (NTRS)

Pilewskie, Peter; Twomey, S.; Gore, Warren J. Y. (Technical Monitor)

1996-01-01

Surface based near-infrared cloud spectral transmission measurements from a recent precipitation/cloud physics field study are used to determine cloud physical properties and relate them to other remote sensing and in situ measurements. Asymptotic formulae provide an effective means of closely approximating the qualitative and quantitative behavior of transmission computed by more laborious detailed methods. Relationships derived from asymptotic formulae are applied to measured transmission spectra to test objectively the internal consistency of data sets acquired during the field program and they confirmed the quality of the measurements. These relationships appear to be very useful in themselves, not merely as a quality control measure, but also a potentially valuable remote-sensing technique in its own right. Additional benefits from this analysis have been the separation of condensed water (cloud) transmission and water vapor transmission and the development of a method to derive cloud liquid water content.

Infection and Transmission of Rift Valley Fever Viruses Lacking the NSs and/or NSm Genes in Mosquitoes: Potential Role for NSm in Mosquito Infection

PubMed Central

Crabtree, Mary B.; Kent Crockett, Rebekah J.; Bird, Brian H.; Nichol, Stuart T.; Erickson, Bobbie Rae; Biggerstaff, Brad J.; Horiuchi, Kalanthe; Miller, Barry R.

2012-01-01

Background Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. Methodology and Principal Findings Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. Conclusions/Significance In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes. PMID:22563517

Infection and transmission of Rift Valley fever viruses lacking the NSs and/or NSm genes in mosquitoes: potential role for NSm in mosquito infection.

PubMed

Crabtree, Mary B; Kent Crockett, Rebekah J; Bird, Brian H; Nichol, Stuart T; Erickson, Bobbie Rae; Biggerstaff, Brad J; Horiuchi, Kalanthe; Miller, Barry R

2012-01-01

Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes.

Transmission Pathways and Mediators as the Basis for Clinical Pharmacology of Pain

PubMed Central

Kirkpatrick, Daniel R.; McEntire, Dan M.; Smith, Tyler A.; Dueck, Nicholas P.; Kerfeld, Mitchell J.; Hambsch, Zakary J.; Nelson, Taylor J.; Reisbig, Mark D.; Agrawal, Devendra K.

2016-01-01

Introduction Mediators in pain transmission are the targets of a multitude of different analgesic pharmaceuticals. This review explores the most significant mediators of pain transmission as well as the pharmaceuticals that act on them. Areas Covered The review explores many of the key mediators of pain transmission. In doing so, this review uncovers important areas for further research. It also highlights agents with potential for producing novel analgesics, probes important interactions between pain transmission pathways that could contribute to synergistic analgesia, and emphasizes transmission factors that participate in transforming acute injury into chronic pain. Expert Commentary This review examines current pain research, particularly in the context of identifying novel analgesics, highlighting interactions between analgesic transmission pathways, and discussing factors that may contribute to the development of chronic pain after an acute injury. PMID:27322358

High-temperature superconductors for space power transmission lines

NASA Astrophysics Data System (ADS)

Hull, John R.; Myers, Ira T.

1989-08-01

Analysis of high temperature superconductors (HTS) for space power transmission lines shows that they have the potential to provide low weight alternatives to conventional power distribution systems, especially for line lengths greater than 100 m. The use of directional radiators, combined with the natural vacuum of space, offers the possibility of reducing or eliminating the heat flux from the environment that dominates loss in terrestrial systems. This leads to scaling laws that favor flat conductor geometries. From a total launch weight viewpoint, HTS transmission lines appear superior, even with presently attainable values of current density.

A vectorial capacity product to monitor changing malaria transmission potential in epidemic regions of Africa

USGS Publications Warehouse

Ceccato, Pietro; Vancutsem, Christelle; Klaver, Robert; Rowland, James; Connor, Stephen J.

2012-01-01

Rainfall and temperature are two of the major factors triggering malaria epidemics in warm semi-arid (desert-fringe) and high altitude (highland-fringe) epidemic risk areas. The ability of the mosquitoes to transmit Plasmodium spp. is dependent upon a series of biological features generally referred to as vectorial capacity. In this study, the vectorial capacity model (VCAP) was expanded to include the influence of rainfall and temperature variables on malaria transmission potential. Data from two remote sensing products were used to monitor rainfall and temperature and were integrated into the VCAP model. The expanded model was tested in Eritrea and Madagascar to check the viability of the approach. The analysis of VCAP in relation to rainfall, temperature and malaria incidence data in these regions shows that the expanded VCAP correctly tracks the risk of malaria both in regions where rainfall is the limiting factor and in regions where temperature is the limiting factor. The VCAP maps are currently offered as an experimental resource for testing within Malaria Early Warning applications in epidemic prone regions of sub-Saharan Africa. User feedback is currently being collected in preparation for further evaluation and refinement of the VCAP model.

Brain potentials predict learning, transmission and modification of an artificial symbolic system.

PubMed

Lumaca, Massimo; Baggio, Giosuè

2016-12-01

It has recently been argued that symbolic systems evolve while they are being transmitted across generations of learners, gradually adapting to the relevant brain structures and processes. In the context of this hypothesis, little is known on whether individual differences in neural processing capacity account for aspects of 'variation' observed in symbolic behavior and symbolic systems. We addressed this issue in the domain of auditory processing. We conducted a combined behavioral and EEG study on 2 successive days. On day 1, participants listened to standard and deviant five-tone sequences: as in previous oddball studies, an mismatch negativity (MMN) was elicited by deviant tones. On day 2, participants learned an artificial signaling system from a trained confederate of the experimenters in a coordination game in which five-tone sequences were associated to affective meanings (emotion-laden pictures of human faces). In a subsequent game with identical structure, participants transmitted and occasionally changed the signaling system learned during the first game. The MMN latency from day 1 predicted learning, transmission and structural modification of signaling systems on day 2. Our study introduces neurophysiological methods into research on cultural transmission and evolution, and relates aspects of variation in symbolic systems to individual differences in neural information processing. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Development of a transmission-blocking malaria vaccine: progress, challenges, and the path forward.

PubMed

Nunes, Julia K; Woods, Colleen; Carter, Terrell; Raphael, Theresa; Morin, Merribeth J; Diallo, Diadier; Leboulleux, Didier; Jain, Sanjay; Loucq, Christian; Kaslow, David C; Birkett, Ashley J

2014-09-29

New interventions are needed to reduce morbidity and mortality associated with malaria, as well as to accelerate elimination and eventual eradication. Interventions that can break the cycle of parasite transmission, and prevent its reintroduction, will be of particular importance in achieving the eradication goal. In this regard, vaccines that interrupt malaria transmission (VIMT) have been highlighted as an important intervention, including transmission-blocking vaccines that prevent human-to-mosquito transmission by targeting the sexual, sporogonic, or mosquito stages of the parasite (SSM-VIMT). While the significant potential of this vaccine approach has been appreciated for decades, the development and licensure pathways for vaccines that target transmission and the incidence of infection, as opposed to prevention of clinical malaria disease, remain ill-defined. This article describes the progress made in critical areas since 2010, highlights key challenges that remain, and outlines important next steps to maximize the potential for SSM-VIMTs to contribute to the broader malaria elimination and eradication objectives. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Microcomputer-assisted transmission of disaster data by cellular telephone.

PubMed

Wigder, H N; Fligner, D J; Rivers, D; Hotch, D

1989-01-01

Voice communication of information during disasters is often inadequate. In particular, simultaneous transmission by multiple callers on the same frequency can result in blocked transmissions and miscommunications. In contrast, nonvoice transmission of data requires less time than does voice communication of the same data, and may be more accurate. We conducted a pilot study to test the feasibility of a microcomputer assisted communication (MAC) network linking the disaster scene and the command hospital. The radio chosen to transmit data from the field disaster site to the command hospital was a cellular telephone connected to the microcomputer by modem. Typed communications between the microcomputer operators enabled dialogue between the disaster site and the hospitals. A computer program using commercially available software (Symphony by Lotus, Inc.) was written to allow for data entry, data transmission, and reports. Patient data, including age, sex, severity of injury, identification number, major injuries, and hospital destination were successfully transmitted from the disaster site command post to the command hospital. This pilot test demonstrated the potential applicability of MAC for facilitating transmission of patient data during a disaster.

Transmission of climate risks across sectors and borders.

PubMed

Challinor, Andy J; Adger, W Neil; Benton, Tim G; Conway, Declan; Joshi, Manoj; Frame, Dave

2018-06-13

Systemic climate risks, which result from the potential for cascading impacts through inter-related systems, pose particular challenges to risk assessment, especially when risks are transmitted across sectors and international boundaries. Most impacts of climate variability and change affect regions and jurisdictions in complex ways, and techniques for assessing this transmission of risk are still somewhat limited. Here, we begin to define new approaches to risk assessment that can account for transboundary and trans-sector risk transmission, by presenting: (i) a typology of risk transmission that distinguishes clearly the role of climate versus the role of the social and economic systems that distribute resources; (ii) a review of existing modelling, qualitative and systems-based methods of assessing risk and risk transmission; and (iii) case studies that examine risk transmission in human displacement, food, water and energy security. The case studies show that policies and institutions can attenuate risks significantly through cooperation that can be mutually beneficial to all parties. We conclude with some suggestions for assessment of complex risk transmission mechanisms: use of expert judgement; interactive scenario building; global systems science and big data; innovative use of climate and integrated assessment models; and methods to understand societal responses to climate risk. These approaches aim to inform both research and national-level risk assessment. © 2018 The Author(s).

Transmissible cancers in an evolutionary context.

PubMed

Ujvari, Beata; Papenfuss, Anthony T; Belov, Katherine

2016-07-01

Cancer is an evolutionary and ecological process in which complex interactions between tumour cells and their environment share many similarities with organismal evolution. Tumour cells with highest adaptive potential have a selective advantage over less fit cells. Naturally occurring transmissible cancers provide an ideal model system for investigating the evolutionary arms race between cancer cells and their surrounding micro-environment and macro-environment. However, the evolutionary landscapes in which contagious cancers reside have not been subjected to comprehensive investigation. Here, we provide a multifocal analysis of transmissible tumour progression and discuss the selection forces that shape it. We demonstrate that transmissible cancers adapt to both their micro-environment and macro-environment, and evolutionary theories applied to organisms are also relevant to these unique diseases. The three naturally occurring transmissible cancers, canine transmissible venereal tumour (CTVT) and Tasmanian devil facial tumour disease (DFTD) and the recently discovered clam leukaemia, exhibit different evolutionary phases: (i) CTVT, the oldest naturally occurring cell line is remarkably stable; (ii) DFTD exhibits the signs of stepwise cancer evolution; and (iii) clam leukaemia shows genetic instability. While all three contagious cancers carry the signature of ongoing and fairly recent adaptations to selective forces, CTVT appears to have reached an evolutionary stalemate with its host, while DFTD and the clam leukaemia appear to be still at a more dynamic phase of their evolution. Parallel investigation of contagious cancer genomes and transcriptomes and of their micro-environment and macro-environment could shed light on the selective forces shaping tumour development at different time points: during the progressive phase and at the endpoint. A greater understanding of transmissible cancers from an evolutionary ecology perspective will provide novel avenues for

Modelling climate change and malaria transmission.

PubMed

Parham, Paul E; Michael, Edwin

2010-01-01

The impact of climate change on human health has received increasing attention in recent years, with potential impacts due to vector-borne diseases only now beginning to be understood. As the most severe vector-borne disease, with one million deaths globally in 2006, malaria is thought most likely to be affected by changes in climate variables due to the sensitivity of its transmission dynamics to environmental conditions. While considerable research has been carried out using statistical models to better assess the relationship between changes in environmental variables and malaria incidence, less progress has been made on developing process-based climate-driven mathematical models with greater explanatory power. Here, we develop a simple model of malaria transmission linked to climate which permits useful insights into the sensitivity of disease transmission to changes in rainfall and temperature variables. Both the impact of changes in the mean values of these key external variables and importantly temporal variation in these values are explored. We show that the development and analysis of such dynamic climate-driven transmission models will be crucial to understanding the rate at which P. falciparum and P. vivax may either infect, expand into or go extinct in populations as local environmental conditions change. Malaria becomes endemic in a population when the basic reproduction number R0 is greater than unity and we identify an optimum climate-driven transmission window for the disease, thus providing a useful indicator for determing how transmission risk may change as climate changes. Overall, our results indicate that considerable work is required to better understand ways in which global malaria incidence and distribution may alter with climate change. In particular, we show that the roles of seasonality, stochasticity and variability in environmental variables, as well as ultimately anthropogenic effects, require further study. The work presented here

Transmission and Distribution Efficiency Improvement Rearch and Development Survey.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brooks, C.L.; Westinghouse Electric Corporation. Advanced Systems Technology.

Purpose of this study was to identify and quantify those technologies for improving transmission and distribution (T and D) system efficiency that could provide the greatest benefits for utility customers in the Pacific Northwest. Improving the efficiency of transmission and distribution systems offers a potential source of conservation within the utility sector. An extensive review of this field resulted in a list of 49 state-of-the-art technologies and 39 future technologies. Of these, 15 from the former list and 7 from the latter were chosen as the most promising and then submitted to an evaluative test - a modeled sample systemmore » for Benton County PUD, a utility with characteristics typical of a BPA customer system. Reducing end-use voltage on secondary distribution systems to decrease the energy consumption of electrical users when possible, called ''Conservation Voltage Reduction,'' was found to be the most cost effective state-of-the-art technology. Voltampere reactive (var) optimization is a similarly cost effective alternative. The most significant reduction in losses on the transmission and distribution system would be achieved through the replacement of standard transformers with high efficiency transformers, such as amorphous steel transformers. Of the future technologies assessed, the ''Distribution Static VAR Generator'' appears to have the greatest potential for technological breakthroughs and, therefore in time, commercialization. ''Improved Dielectric Materials,'' with a relatively low cost and high potential for efficiency improvement, warrant R and D consideration. ''Extruded Three-Conductor Cable'' and ''Six- and Twelve-Phase Transmission'' programs provide only limited gains in efficiency and applicability and are therefore the least cost effective.« less

Review Article: Influenza Transmission on Aircraft

PubMed Central

Adlhoch, Cornelia

2016-01-01

Background: Air travel is associated with the spread of influenza through infected passengers and potentially through in-flight transmission. Contact tracing after exposure to influenza is not performed systematically. We performed a systematic literature review to evaluate the evidence for influenza transmission aboard aircraft. Methods: Using PubMed and EMBASE databases, we identified and critically appraised identified records to assess the evidence of such transmission to passengers seated in close proximity to the index cases. We also developed a bias assessment tool to evaluate the quality of evidence provided in the retrieved studies. Results: We identified 14 peer-reviewed publications describing contact tracing of passengers after possible exposure to influenza virus aboard an aircraft. Contact tracing during the initial phase of the influenza A(H1N1)pdm09 pandemic was described in 11 publications. The studies describe the follow-up of 2,165 (51%) of 4,252 traceable passengers. Altogether, 163 secondary cases were identified resulting in an overall secondary attack rate among traced passengers of 7.5%. Of these secondary cases, 68 (42%) were seated within two rows of the index case. Conclusion: We found an overall moderate quality of evidence for transmission of influenza virus aboard an aircraft. The major limiting factor was the comparability of the studies. A majority of secondary cases was identified at a greater distance than two rows from the index case. A standardized approach for initiating, conducting, and reporting contact tracing could help to increase the evidence base for better assessing influenza transmission aboard aircraft. PMID:27253070

Pulse transmission transmitter including a higher order time derivate filter

DOEpatents

Dress, Jr., William B.; Smith, Stephen F.

2003-09-23

Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission transmitter includes: a clock; a pseudorandom polynomial generator coupled to the clock, the pseudorandom polynomial generator having a polynomial load input; an exclusive-OR gate coupled to the pseudorandom polynomial generator, the exclusive-OR gate having a serial data input; a programmable delay circuit coupled to both the clock and the exclusive-OR gate; a pulse generator coupled to the programmable delay circuit; and a higher order time derivative filter coupled to the pulse generator. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

Bordetella pertussis transmission

PubMed Central

Trainor, Elizabeth A.; Nicholson, Tracy L.; Merkel, Tod J.

2015-01-01

Bordetella pertussis and B. bronchiseptica are Gram-negative bacterial respiratory pathogens. Bordetella pertussis is the causative agent of whooping cough and is considered a human-adapted variant of B. bronchiseptica. Bordetella pertussis and B. bronchiseptica share mechanisms of pathogenesis and are genetically closely related. However, despite the close genetic relatedness, these Bordetella species differ in several classic fundamental aspects of bacterial pathogens such as host range, pathologies and persistence. The development of the baboon model for the study of B. pertussis transmission, along with the development of the swine and mouse model for the study of B. bronchiseptica, has enabled the investigation of different aspects of transmission including the route, attack rate, role of bacterial and host factors, and the impact of vaccination on transmission. This review will focus on B. pertussis transmission and how animal models of B. pertussis transmission and transmission models using the closely related B. bronchiseptica have increased our understanding of B. pertussis transmission. PMID:26374235

Dynamics of Mycobacterium leprae transmission in environmental context: deciphering the role of environment as a potential reservoir.

PubMed

Turankar, Ravindra P; Lavania, Mallika; Singh, Mradula; Siva Sai, Krovvidi S R; Jadhav, Rupendra S

2012-01-01

Leprosy is a disease caused by Mycobacterium leprae. Various modes of transmission have been suggested for this disease. Transmission and risk of the infection is perhaps related to presence of the infectious cases and is controlled by environmental factors. Evidence suggests that humidity may favor survival of M. leprae in the environment. Several reports show that non-human sources like 'naturally' infected armadillos or monkeys could act as reservoir for M. leprae. Inanimate objects or fomites like articles used by infectious patients may theoretically spread infection. However, it is only through detailed knowledge of the biodiversity and ecology that the importance of this mode of transmission can be fully assessed. Our study focuses here to decipher the role of environment in the transmission of the disease. Two hundred and seven soil samples were collected from a village in endemic area where active cases also resided at the time of sample collection. Slit skin smears were collected from 13 multibacillary (MB) leprosy patients and 12 household contacts of the patients suspected to be hidden cases. DNA and RNA of M. leprae were extracted and amplified using M. leprae specific primers. Seventy-one soil samples showed presence of M. leprae DNA whereas 16S rRNA could be detected in twenty-eight of these samples. Samples, both from the environment and the patients, exhibited the same genotype when tested by single nucleotide polymorphism (SNP) typing. Genotype of M. leprae found in the soil and the patients residing in the same area could help in understanding the transmission link in leprosy. Copyright © 2011 Elsevier B.V. All rights reserved.

Interaction potentials of anisotropic nanocrystals from the trajectory sampling of particle motion using in situ liquid phase transmission electron microscopy

DOE PAGES

Chen, Qian; Cho, Hoduk; Manthiram, Karthish; ...

2015-03-23

We demonstrate a generalizable strategy to use the relative trajectories of pairs and groups of nanocrystals, and potentially other nanoscale objects, moving in solution which can now be obtained by in situ liquid phase transmission electron microscopy (TEM) to determine the interaction potentials between nanocrystals. Such nanoscale interactions are crucial for collective behaviors and applications of synthetic nanocrystals and natural biomolecules, but have been very challenging to measure in situ at nanometer or sub-nanometer resolution. Here we use liquid phase TEM to extract the mathematical form of interaction potential between nanocrystals from their sampled trajectories. We show the power ofmore » this approach to reveal unanticipated features of nanocrystal–nanocrystal interactions by examining the anisotropic interaction potential between charged rod-shaped Au nanocrystals (Au nanorods); these Au nanorods assemble, in a tip-to-tip fashion in the liquid phase, in contrast to the well-known side-by-side arrangements commonly observed for drying-mediated assembly. These observations can be explained by a long-range and highly anisotropic electrostatic repulsion that leads to the tip-selective attachment. As a result, Au nanorods stay unassembled at a lower ionic strength, as the electrostatic repulsion is even longer-ranged. Our study not only provides a mechanistic understanding of the process by which metallic nanocrystals assemble but also demonstrates a method that can potentially quantify and elucidate a broad range of nanoscale interactions relevant to nanotechnology and biophysics.« less

NASA transmission research and its probable effects on helicopter transmission design

NASA Technical Reports Server (NTRS)

Zaretsky, E. V.; Coy, J. J.; Townsend, D. P.

1983-01-01

Transmissions studied for application to helicopters in addition to the more conventional geared transmissions include hybrid (traction/gear), bearingless planetary, and split torque transmissions. Research is being performed to establish the validity of analysis and computer codes developed to predict the performance, efficiency, life, and reliability of these transmissions. Results of this research should provide the transmission designer with analytical tools to design for minimum weight and noise with maximum life and efficiency. In addition, the advantages and limitations of drive systems as well as the more conventional systems will be defined.

NASA transmission research and its probable effects on helicopter transmission design

NASA Technical Reports Server (NTRS)

Zaretsky, E. V.; Coy, J. J.; Townsend, D. P.

1984-01-01

Transmissions studied for application to helicopters in addition to the more conventional geared transmissions include hybrid (traction/gear), bearingless planetary, and split torque transmissions. Research is being performed to establish the validity of analysis and computer codes developed to predict the performance, efficiency, life, and reliability of these transmissions. Results of this research should provide the transmission designer with analytical tools to design for minimum weight and noise with maximum life and efficiency. In addition, the advantages and limitations of drive systems as well as the more conventional systems will be defined.

Planning Electric Transmission Lines: A Review of Recent Regional Transmission Plans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eto, Joseph H.

The first Quadrennial Energy Review (QER) recommends that the U.S. Department of Energy (DOE) conduct a national review of transmission plans and assess the barriers and incentives to their implementation. DOE tasked Lawrence Berkeley National Laboratory (LBNL) to prepare two reports to support the agency’s response to this recommendation. This report reviews regional transmission plans and regional transmission planning processes that have been directed by Federal Energy Regulatory Commission (FERC) Order Nos. 890 and 1000. We focus on the most recent regional transmission plans (those issued in 2015 and through approximately mid-year 2016) and current regional transmission planning processes. Amore » companion report focuses on non-plan-related factors that affect transmission projects.« less

Absence of Frequent Herpesvirus Transmission in a Nonhuman Primate Predator-Prey System in the Wild

PubMed Central

Murthy, Sripriya; Couacy-Hymann, Emmanuel; Metzger, Sonja; Nowak, Kathrin; De Nys, Helene; Boesch, Christophe; Wittig, Roman; Jarvis, Michael A.; Leendertz, Fabian H.

2013-01-01

Emergence of viruses into the human population by transmission from nonhuman primates (NHPs) represents a serious potential threat to human health that is primarily associated with the increased bushmeat trade. Transmission of RNA viruses across primate species appears to be relatively frequent. In contrast, DNA viruses appear to be largely host specific, suggesting low transmission potential. Herein, we use a primate predator-prey system to study the risk of herpesvirus transmission between different primate species in the wild. The system was comprised of western chimpanzees (Pan troglodytes verus) and their primary (western red colobus, Piliocolobus badius badius) and secondary (black-and-white colobus, Colobus polykomos) prey monkey species. NHP species were frequently observed to be coinfected with multiple beta- and gammaherpesviruses (including new cytomegalo- and rhadinoviruses). However, despite frequent exposure of chimpanzees to blood, organs, and bones of their herpesvirus-infected monkey prey, there was no evidence for cross-species herpesvirus transmission. These findings suggest that interspecies transmission of NHP beta- and gammaherpesviruses is, at most, a rare event in the wild. PMID:23885068

Absence of frequent herpesvirus transmission in a nonhuman primate predator-prey system in the wild.

PubMed

Murthy, Sripriya; Couacy-Hymann, Emmanuel; Metzger, Sonja; Nowak, Kathrin; De Nys, Helene; Boesch, Christophe; Wittig, Roman; Jarvis, Michael A; Leendertz, Fabian H; Ehlers, Bernhard

2013-10-01

Emergence of viruses into the human population by transmission from nonhuman primates (NHPs) represents a serious potential threat to human health that is primarily associated with the increased bushmeat trade. Transmission of RNA viruses across primate species appears to be relatively frequent. In contrast, DNA viruses appear to be largely host specific, suggesting low transmission potential. Herein, we use a primate predator-prey system to study the risk of herpesvirus transmission between different primate species in the wild. The system was comprised of western chimpanzees (Pan troglodytes verus) and their primary (western red colobus, Piliocolobus badius badius) and secondary (black-and-white colobus, Colobus polykomos) prey monkey species. NHP species were frequently observed to be coinfected with multiple beta- and gammaherpesviruses (including new cytomegalo- and rhadinoviruses). However, despite frequent exposure of chimpanzees to blood, organs, and bones of their herpesvirus-infected monkey prey, there was no evidence for cross-species herpesvirus transmission. These findings suggest that interspecies transmission of NHP beta- and gammaherpesviruses is, at most, a rare event in the wild.

Bordetella pertussis transmission.

PubMed

Trainor, Elizabeth A; Nicholson, Tracy L; Merkel, Tod J

2015-11-01

Bordetella pertussis and B. bronchiseptica are Gram-negative bacterial respiratory pathogens. Bordetella pertussis is the causative agent of whooping cough and is considered a human-adapted variant of B. bronchiseptica. Bordetella pertussis and B. bronchiseptica share mechanisms of pathogenesis and are genetically closely related. However, despite the close genetic relatedness, these Bordetella species differ in several classic fundamental aspects of bacterial pathogens such as host range, pathologies and persistence. The development of the baboon model for the study of B. pertussis transmission, along with the development of the swine and mouse model for the study of B. bronchiseptica, has enabled the investigation of different aspects of transmission including the route, attack rate, role of bacterial and host factors, and the impact of vaccination on transmission. This review will focus on B. pertussis transmission and how animal models of B. pertussis transmission and transmission models using the closely related B. bronchiseptica have increased our understanding of B. pertussis transmission. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Vertical Transmission of Zika Virus by Aedes aegypti and Ae. albopictus Mosquitoes.

PubMed

Ciota, Alexander T; Bialosuknia, Sean M; Ehrbar, Dylan J; Kramer, Laura D

2017-05-01

To determine the potential role of vertical transmission in Zika virus expansion, we evaluated larval pools of perorally infected Aedes aegypti and Ae. albopictus adult female mosquitoes; ≈1/84 larvae tested were Zika virus-positive; and rates varied among mosquito populations. Thus, vertical transmission may play a role in Zika virus spread and maintenance.

Assessing the role of landscape connectivity on Opisthorchis viverrini transmission dynamics.

PubMed

Wang, Yi-Chen; Yuen, Roy; Feng, Chen-Chieh; Sithithaworn, Paiboon; Kim, Ick-Hoi

2017-08-01

Opisthorchis viverrini (Ov) is one of the most important human parasitic diseases in Southeast Asia. Although the concept of connectivity is widely used to comprehend disease dispersal, knowledge of the influences of landscape connectivity on Ov transmission is still rudimentary. This study aimed to investigate the role of landscape connectivity in Ov transmission between the human and the first intermediate snail hosts. Fieldwork was conducted in three villages respectively in Kamalasai District, Kalasin Province, Phu Wiang District, Khon Kaen Province, and Nong Saeng District, Udon Thani Province. Bithynia snails were collected to examine parasitic infections, water samples were analyzed for fecal contamination, and locations of septic tanks and connections between habitat patches with observable water movement were surveyed. Euclidean distance, topological link and distance, and graph measures were employed to quantify the connectivity between human and snail habitats. The findings showed that snail patches with higher fecal contents were generally located nearer to septic tanks. The statistically significant results for the topological link and distance measures highlighted the importance of water in functionally facilitating Ov transmission. Graph measures revealed differences in landscape connectivity across the sites. The site with the largest landscape component size and the most mutually connected snail patches coincided with the presence of Ov parasite, reinforcing its higher risk for human to snail transmission. The site with the dissected landscape structure potentially limited the transmission. This study underscored the potential effect of landscape connectivity on Ov transmission, contributing to the understanding of the spatial variation of Ov infection risk. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Estimating potential infection transmission routes in hospital wards using wearable proximity sensors.

PubMed

Vanhems, Philippe; Barrat, Alain; Cattuto, Ciro; Pinton, Jean-François; Khanafer, Nagham; Régis, Corinne; Kim, Byeul-a; Comte, Brigitte; Voirin, Nicolas

2013-01-01

Contacts between patients, patients and health care workers (HCWs) and among HCWs represent one of the important routes of transmission of hospital-acquired infections (HAI). A detailed description and quantification of contacts in hospitals provides key information for HAIs epidemiology and for the design and validation of control measures. We used wearable sensors to detect close-range interactions ("contacts") between individuals in the geriatric unit of a university hospital. Contact events were measured with a spatial resolution of about 1.5 meters and a temporal resolution of 20 seconds. The study included 46 HCWs and 29 patients and lasted for 4 days and 4 nights. 14,037 contacts were recorded overall, 94.1% of which during daytime. The number and duration of contacts varied between mornings, afternoons and nights, and contact matrices describing the mixing patterns between HCW and patients were built for each time period. Contact patterns were qualitatively similar from one day to the next. 38% of the contacts occurred between pairs of HCWs and 6 HCWs accounted for 42% of all the contacts including at least one patient, suggesting a population of individuals who could potentially act as super-spreaders. Wearable sensors represent a novel tool for the measurement of contact patterns in hospitals. The collected data can provide information on important aspects that impact the spreading patterns of infectious diseases, such as the strong heterogeneity of contact numbers and durations across individuals, the variability in the number of contacts during a day, and the fraction of repeated contacts across days. This variability is however associated with a marked statistical stability of contact and mixing patterns across days. Our results highlight the need for such measurement efforts in order to correctly inform mathematical models of HAIs and use them to inform the design and evaluation of prevention strategies.

Advanced continuously variable transmissions for electric and hybrid vehicles

NASA Technical Reports Server (NTRS)

Loewenthal, S. H.

1980-01-01

A brief survey of past and present continuously variable transmissions (CVT) which are potentially suitable for application with electric and hybrid vehicles is presented. Discussion of general transmission requirements and benefits attainable with a CVT for electric vehicle use is given. The arrangement and function of several specific CVT concepts are cited along with their current development status. Lastly, the results of preliminary design studies conducted under a NASA contract for DOE on four CVT concepts for use in advanced electric vehicles are reviewed.

The Transmission Channel Tower Identification and Landslide Disaster Monitoring Based on Insar

NASA Astrophysics Data System (ADS)

Li, G.; Tan, Q.; Xie, C.; Fei, X.; Ma, X.; Zhao, B.; Ou, W.; Yang, Z.; Wang, J.; Fang, H.

2018-04-01

The transmission distance of transmission lines is long, the line affected by the diversity of climate and topography of the corridors of transmission lines, differences in regional geological structure conditions, variability of rock and soil types, and the complexity of groundwater. Under the influence of extreme weather conditions (ice-covered, strong wind, etc.) and sudden geological disasters (such as mudslides, flash floods, earthquakes, etc.), catastrophic damage and basic deformation problems of the tower foundations are prone, and even tower collapse accidents occur in severe cases, which affect the safe operation of transmission lines. Monitoring the deformation of power transmission towers and surrounding grounds, it is critical to ensuring the normal operation of transmission lines by assessing and controlling potential risks in advance. In this paper, using ALOS-2 PALSAR radar satellite data, differential interferometry was used to monitor surface deformation near the Sichuan Jinsu line transmission channel. The analysis found that a significant landslide hazard was found near the transmission channel tower in Yibin-Zhaotong section of Jinsu, Sichuan Province, the cumulative deformation reaches 9cm. The results of this paper can provide new monitoring means for safety monitoring of transmission towers.

Association of preS/S Mutations with Occult Hepatitis B Virus (HBV) Infection in South Korea: Transmission Potential of Distinct Occult HBV Variants

PubMed Central

Kim, Hong; Kim, Bum-Joon

2015-01-01

Occult hepatitis B virus infection (HBV) is characterized by HBV DNA positivity but HBV surface antigen (HBsAg) negativity. Occult HBV infection is associated with a risk of HBV transmission through blood transfusion, hemodialysis, and liver transplantation. Furthermore, occult HBV infection contributes to the development of cirrhosis and hepatocellular carcinoma. We recently reported the characteristic molecular features of mutations in the preS/S regions among Korean individuals with occult infections caused by HBV genotype C2; the variants of preS and S related to severe liver diseases among chronically infected patients were also responsible for the majority of HBV occult infections. We also reported that HBsAg variants from occult-infected Korean individuals exhibit lower HBsAg secretion capacity but not reduced HBV DNA levels. In addition, these variants exhibit increased ROS-inducing capacity compared with the wild-type strain, linking HBV occult infections to liver cell damage. Taken together, our previous reports suggest the transmission potential of distinct HBV occult infection-related variants in South Korea. PMID:26084041

Association of preS/S Mutations with Occult Hepatitis B Virus (HBV) Infection in South Korea: Transmission Potential of Distinct Occult HBV Variants.

PubMed

Kim, Hong; Kim, Bum-Joon

2015-06-15

Occult hepatitis B virus infection (HBV) is characterized by HBV DNA positivity but HBV surface antigen (HBsAg) negativity. Occult HBV infection is associated with a risk of HBV transmission through blood transfusion, hemodialysis, and liver transplantation. Furthermore, occult HBV infection contributes to the development of cirrhosis and hepatocellular carcinoma. We recently reported the characteristic molecular features of mutations in the preS/S regions among Korean individuals with occult infections caused by HBV genotype C2; the variants of preS and S related to severe liver diseases among chronically infected patients were also responsible for the majority of HBV occult infections. We also reported that HBsAg variants from occult-infected Korean individuals exhibit lower HBsAg secretion capacity but not reduced HBV DNA levels. In addition, these variants exhibit increased ROS-inducing capacity compared with the wild-type strain, linking HBV occult infections to liver cell damage. Taken together, our previous reports suggest the transmission potential of distinct HBV occult infection-related variants in South Korea.

New Insights Into the Transmissibility of Leishmania infantum From Dogs to Sand Flies: Experimental Vector-Transmission Reveals Persistent Parasite Depots at Bite Sites

PubMed Central

Aslan, Hamide; Oliveira, Fabiano; Meneses, Claudio; Castrovinci, Philip; Gomes, Regis; Teixeira, Clarissa; Derenge, Candace A.; Orandle, Marlene; Gradoni, Luigi; Oliva, Gaetano; Fischer, Laurent; Valenzuela, Jesus G.; Kamhawi, Shaden

2016-01-01

Canine leishmaniasis (CanL) is a chronic fatal disease of dogs and a major source of human infection through propagation of parasites in vectors. Here, we infected 8 beagles through multiple experimental vector transmissions with Leishmania infantum–infected Lutzomyia longipalpis. CanL clinical signs varied, although live parasites were recovered from all dog spleens. Splenic parasite burdens correlated positively with Leishmania-specific interleukin 10 levels, negatively with Leishmania-specific interferon γ and interleukin 2 levels, and negatively with Leishmania skin test reactivity. A key finding was parasite persistence for 6 months in lesions observed at the bite sites in all dogs. These recrudesced following a second transmission performed at a distal site. Notably, sand flies efficiently acquired parasites after feeding on lesions at the primary bite site. In this study, controlled vector transmissions identify a potentially unappreciated role for skin at infectious bite sites in dogs with CanL, providing a new perspective regarding the mechanism of Leishmania transmissibility to vector sand flies. PMID:26768257

Inferring Plasmodium vivax Transmission Networks from Tempo-Spatial Surveillance Data

PubMed Central

Shi, Benyun; Liu, Jiming; Zhou, Xiao-Nong; Yang, Guo-Jing

2014-01-01

Background The transmission networks of Plasmodium vivax characterize how the parasite transmits from one location to another, which are informative and insightful for public health policy makers to accurately predict the patterns of its geographical spread. However, such networks are not apparent from surveillance data because P. vivax transmission can be affected by many factors, such as the biological characteristics of mosquitoes and the mobility of human beings. Here, we pay special attention to the problem of how to infer the underlying transmission networks of P. vivax based on available tempo-spatial patterns of reported cases. Methodology We first define a spatial transmission model, which involves representing both the heterogeneous transmission potential of P. vivax at individual locations and the mobility of infected populations among different locations. Based on the proposed transmission model, we further introduce a recurrent neural network model to infer the transmission networks from surveillance data. Specifically, in this model, we take into account multiple real-world factors, including the length of P. vivax incubation period, the impact of malaria control at different locations, and the total number of imported cases. Principal Findings We implement our proposed models by focusing on the P. vivax transmission among 62 towns in Yunnan province, People's Republic China, which have been experiencing high malaria transmission in the past years. By conducting scenario analysis with respect to different numbers of imported cases, we can (i) infer the underlying P. vivax transmission networks, (ii) estimate the number of imported cases for each individual town, and (iii) quantify the roles of individual towns in the geographical spread of P. vivax. Conclusion The demonstrated models have presented a general means for inferring the underlying transmission networks from surveillance data. The inferred networks will offer new insights into how to

Automated manual transmission controller

DOEpatents

Lawrie, Robert E.; Reed, Jr., Richard G.; Bernier, David R.

1999-12-28

A powertrain system for a hybrid vehicle. The hybrid vehicle includes a heat engine, such as a diesel engine, and an electric machine, which operates as both an electric motor and an alternator, to power the vehicle. The hybrid vehicle also includes a manual-style transmission configured to operate as an automatic transmission from the perspective of the driver. The engine and the electric machine drive an input shaft which in turn drives an output shaft of the transmission. In addition to driving the transmission, the electric machine regulates the speed of the input shaft in order to synchronize the input shaft during either an upshift or downshift of the transmission by either decreasing or increasing the speed of the input shaft. When decreasing the speed of the input shaft, the electric motor functions as an alternator to produce electrical energy which may be stored by a storage device. Operation of the transmission is controlled by a transmission controller which receives input signals and generates output signals to control shift and clutch motors to effect smooth launch, upshift shifts, and downshifts of the transmission, so that the transmission functions substantially as an automatic transmission from the perspective of the driver, while internally substantially functioning as a manual transmission.

Immune Evasion Strategies of Pathogens in Macrophages: the Potential for Limiting Pathogen Transmission.

PubMed

Ren, Yuwei; Khan, Faheem Ahmed; Pandupuspitasari, Nuruliarizki Shinta; Zhang, Shujun

2017-01-01

Preventing pathogen transmission to a new host is of major interest to the immunologist and could benefit from a detailed investigation of pathogen immune evasion strategies. The first line of defense against pathogen invasion is provided by macrophages. When they sense pathogens, macrophages initiate signals to inflammatory and pro-inflammatory cytokines through pattern recognition receptors (PRRs) subsequently mediating phagocytosis and inflammation. The macrophage immune machinery classically includes two subsets: the activated M1 and the activated M2 that respond accordingly in diverse immune challenges. The lipid and glycogen metabolic pathways work together with the lysosome to help the mature phagosome to degrade and eliminate intracellular pathogens in macrophages. The viral evasion strategies are even more complex due to the interplay between autophagy and apoptosis. However, pathogens evolve several strategies to camouflage themselves against immune responses in order to ensure their survival, replication and transmission. These strategies include the muting of PRRs initiated inflammatory responses, attenuation of M1 and/or induction of M2 macrophages, suppression of autophago-lysosomal formation, interference with lipid and glycogen metabolism, and viral mediation of autophagy and apoptosis cross-talk to enhance viral replication. This review focuses on pathogen immune evasion methods and on the strategies used by the host against camouflaged pathogens.

Assessment of the Probability of Autochthonous Transmission of Chikungunya Virus in Canada under Recent and Projected Climate Change

PubMed Central

Fazil, Aamir; Gachon, Philippe; Deuymes, Guillaume; Radojević, Milka; Mascarenhas, Mariola; Garasia, Sophiya; Johansson, Michael A.; Ogden, Nicholas H.

2017-01-01

Background: Chikungunya virus (CHIKV) is a reemerging pathogen transmitted by Aedes aegypti and Aedes albopictus mosquitoes. The ongoing Caribbean outbreak is of concern due to the potential for infected travelers to spread the virus to countries where vectors are present and the population is susceptible. Although there has been no autochthonous transmission of CHIKV in Canada, there is concern that both Ae. albopictus and CHIKV will become established, particularly under projected climate change. We developed risk maps for autochthonous CHIKV transmission in Canada under recent (1981–2010) and projected climate (2011–2040 and 2041–2070). Methods: The risk for CHIKV transmission was the combination of the climatic suitability for CHIKV transmission potential and the climatic suitability for the presence of Ae. albopictus; the former was assessed using a stochastic model to calculate R0 and the latter was assessed by deriving a suitability indicator (SIG) that captures a set of climatic conditions known to influence the ecology of Ae. albopictus. R0 and SIG were calculated for each grid cell in Canada south of 60°N, for each time period and for two emission scenarios, and combined to produce overall risk categories that were mapped to identify areas suitable for transmission and the duration of transmissibility. Findings: The risk for autochthonous CHIKV transmission under recent climate is very low with all of Canada classified as unsuitable or rather unsuitable for transmission. Small parts of southern coastal British Columbia become progressively suitable with short-term and long-term projected climate; the duration of potential transmission is limited to 1–2 months of the year. Interpretation: Although the current risk for autochthonous CHIKV transmission in Canada is very low, our study could be further supported by the routine surveillance of Ae. albopictus in areas identified as potentially suitable for transmission given our uncertainty on the

Zika Virus: Transmission, Detection, Control, and Prevention

PubMed Central

Sharma, Anshika; Lal, Sunil K.

2017-01-01

Zika virus (ZIKV) is a mosquito-borne Flavivirus discovered in Uganda in the 1940s. To date, three major ZIKV outbreaks have been reported. ZIKV infections have known to be primarily asymptomatic while causing mild illness in a few cases. However, the recent emergence and spread of ZIKV in the Americas has resulted in the declaration of “Public Health Emergency of International Concern” due to the potential association between the infection and prenatal microcephaly or other brain anomalies. In Brazil, a 20-fold increase in prenatal microcephaly cases and 19% increase in Guillain-Barré Syndrome (GBS) cases were reported in 2015, as compared to the preceding year. The probable deleterious effects of ZIKV infection prompt the urgent development of diagnostics and therapeutics. To this end, the existing evidences supporting the increasingly common prenatal microcephaly and GBS association and the current known ZIKV transmission dynamics, modes of detection (molecular and serology-based), and current control strategies are summarized in this review. This review also emphasizes the importance of understanding ZIKV transmission in order to design a sensitive yet cost and time-efficient detection technique. Development of an efficient detection technique would subsequently allow for better surveillance and control of ZIKV infection. Currently, limited literature is available on the pathogenesis of ZIKV, hence, focusing on the modes of ZIKV transmission could potentially contribute to the understanding of the disease spectrum and formulation of targeted treatment and control. PMID:28217114

Molecular characterisation of Galba truncatula, Lymnaea neotropica and L. schirazensis from Cajamarca, Peru and their potential role in transmission of human and animal fascioliasis.

PubMed

Bargues, M Dolores; Artigas, Patricio; Khoubbane, Messaoud; Ortiz, Pedro; Naquira, Cesar; Mas-Coma, Santiago

2012-08-15

Human and animal fascioliasis is emerging in many world regions, among which Andean countries constitute the largest regional hot spot and Peru the country presenting more human endemic areas. A survey was undertaken on the lymnaeid snails inhabiting the hyperendemic area of Cajamarca, where human prevalences are the highest known among the areas presenting a "valley transmission pattern", to establish which species are present, genetically characterise their populations by comparison with other human endemic areas, and discuss which ones have transmission capacity and their potential implications with human and animal infection. Therefore, ribosomal DNA ITS-2 and ITS-1, and mitochondrial DNA 16S and cox1 were sequenced by the dideoxy chain-termination method. Results indicate the presence of three, morphologically similar, small lymnaeid species belonging to the Galba/Fossaria group: Galba truncatula, Lymnaea neotropica and L. schirazensis. Only one combined haplotype for each species was found. The ITS-1, 16S and cox1 haplotypes of G. truncatula are new. No new haplotypes were found in the other two species. This scenario changes previous knowledge, in which only L. viator (= L. viatrix) was mentioned. Galba truncatula appears to be the most abundant, with high population densities and evident anthropophyly including usual presence in human neighbourhood. Infection by Fasciola hepatica larval stages were molecularly confirmed in two populations of this species. The nearness between G. truncatula populations presenting liver fluke infection and both human settings and schools for children, together with the absence of populations of other lymnaeid species in the locality, suggest a direct relationship with human infection. The geographical overlap of three lymnaeid species poses problems for epidemiological studies and control action. First, a problem in classifying lymnaeid specimens in both field and laboratory activities, given their transmission capacity

Supplement Analysis for the Transmission System Vegetation Management Program FEIS (DOE/EIS-0285/SA-40) - Allston-Keeler 500 kV Transmission Line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hermeston, Mark W.

2002-02-19

Vegetation Management along the Allston-Keeler 500 kV Transmission Line ROW exclusive to BLM lands between 8/4 through 27/4. The proposed work will be accomplished in the indicated sections of the transmission line corridor with an average corridor width of 150 feet. BPA proposes to clear unwanted vegetation in the rights-of-ways and around tower structures that may impede the operation and maintenance of the subject transmission lines and access roads, including Reclaim and Danger Trees. The lands in this SA are administered by BLM. BPA plans to conduct vegetation control with the goal of removing tall growing vegetation that is currentlymore » or will soon be a hazard to the transmission line. BPA’s overall goal is to have low-growing plant communities along the rights-of-way to control the development of potentially threatening vegetation. All work will be executed in accordance with the National Electrical Safety Code and BPA standards. Work is to begin in March 2002. In accordance with a court injunction, no chemical treatment is planned on BLM lands.« less

Potential of optical spectral transmission measurements for joint inflammation measurements in rheumatoid arthritis patients

NASA Astrophysics Data System (ADS)

Meier, A. J. Louise; Rensen, Wouter H. J.; de Bokx, Pieter K.; de Nijs, Ron N. J.

2012-08-01

Frequent monitoring of rheumatoid arthritis (RA) patients enables timely treatment adjustments and improved outcomes. Currently this is not feasible due to a shortage of rheumatologists. An optical spectral transmission device is presented for objective assessment of joint inflammation in RA patients, while improving diagnostic accuracy and clinical workflow. A cross-sectional, nonrandomized observational study was performed with this device. In the study, 77 proximal interphalangeal (PIP) joints in 67 patients have been analyzed. Inflammation of these PIP joints was also assessed by a rheumatologist with a score varying from 1 (not inflamed) to 5 (severely inflamed). Out of 77 measurements, 27 were performed in moderate to strongly inflamed PIP joints. Comparison between the clinical assessment and an optical measurement showed a correlation coefficient r=0.63, p<0.001, 95% CI [0.47, 0.75], and a ROC curve (AUC=0.88) that shows a relative good specificity and sensitivity. Optical spectral transmission measurements in a single joint correlate with clinical assessment of joint inflammation, and therefore might be useful in monitoring joint inflammation in RA patients.

Transmission of acoustic emission in bones, implants and dental materials.

PubMed

Ossi, Zannar; Abdou, Wael; Reuben, Robert L; Ibbetson, Richard J

2013-11-01

There is considerable interest in using acoustic emission (AE) and ultrasound to assess the quality of implant-bone interfaces and to monitor for micro-damage leading to loosening. However, remarkably little work has been done on the transmission of ultrasonic waves though the physical and biological structures involved. The aim of this in vitro study is to assess any differences in transmission between various dental materials and bovine rib bones with various degrees of hydration. Two types of tests have been carried out using pencil lead breaks as a standard AE source. The first set of tests was configured to assess the surface propagation of AE on various synthetic materials compared with fresh bovine rib bone. The second is a set of transmission tests on fresh, dried and hydrated bones each fitted with dental implants with various degrees of fixity, which includes components due to bone and interface transmission. The results indicate that transmission through glass ionomer cement is closest to the bone. This would suggest that complete osseointegration could potentially be simulated using such cement. The transmission of AE energy through bone was found to be dependent on its degree of hydration. It was also found that perfusing samples of fresh bone with water led to an increase in transmitted energy, but this appeared to affect transmission across the interface more than transmission through the bone. These findings have implications not only for implant interface inspection but also for passive AE monitoring of implants.

The complex relationship between weather and dengue virus transmission in Thailand.

PubMed

Campbell, Karen M; Lin, C D; Iamsirithaworn, Sopon; Scott, Thomas W

2013-12-01

Using a novel analytical approach, weather dynamics and seasonal dengue virus transmission cycles were profiled for each Thailand province, 1983-2001, using monthly assessments of cases, temperature, humidity, and rainfall. We observed systematic differences in the structure of seasonal transmission cycles of different magnitude, the role of weather in regulating seasonal cycles, necessary versus optimal transmission "weather-space," basis of large epidemics, and predictive indicators that estimate risk. Larger epidemics begin earlier, develop faster, and are predicted at Onset change-point when case counts are low. Temperature defines a viable range for transmission; humidity amplifies the potential within that range. This duality is central to transmission. Eighty percent of 1.2 million severe dengue cases occurred when mean temperature was 27-29.5°C and mean humidity was > 75%. Interventions are most effective when applied early. Most cases occur near Peak, yet small reductions at Onset can substantially reduce epidemic magnitude. Monitoring the Quiet-Phase is fundamental in effectively targeting interventions pre-emptively.

Aerosol transmission of foot-and-mouth disease virus Asia-1 under experimental conditions.

PubMed

Colenutt, C; Gonzales, J L; Paton, D J; Gloster, J; Nelson, N; Sanders, C

2016-06-30

Foot-and-mouth disease virus (FMDV) control measures rely on understanding of virus transmission mechanisms. Direct contact between naïve and infected animals or spread by contaminated fomites is prevented by quarantines and rigorous decontamination procedures during outbreaks. Transmission of FMDV by aerosol may not be prevented by these control measures and this route of transmission may allow infection of animals at distance from the infection source. Understanding the potential for aerosol spread of specific FMDV strains is important for informing control strategies in an outbreak. Here, the potential for transmission of an FMDV Asia 1 strain between pigs and cattle by indirect aerosol exposure was evaluated in an experimental setting. Four naïve calves were exposed to aerosols emitted from three infected pigs in an adjacent room for a 10h period. Direct contact between pigs and cattle and fomite transfer between rooms was prevented. Viral titres in aerosols emitted by the infected pigs were measured to estimate the dose that calves were exposed to. One of the calves developed clinical signs of FMD, whilst there was serological evidence for spread to cattle by aerosol transmission in the remaining three calves. This highlights the possibility that this FMDV Asia 1 strain could be spread by aerosol transmission given appropriate environmental conditions should an outbreak occur in pigs. Our estimates suggest the exposure dose required for aerosol transmission was higher than has been previously quantified for other serotypes, implying that aerosols are less likely to play a significant role in transmission and spread of this FMDV strain. Copyright © 2016 Elsevier B.V. All rights reserved.

Breaking Transmission with Vaccines: The Case of Tuberculosis.

PubMed

Gonzalo-Asensio, Jesus; Aguilo, Nacho; Marinova, Dessislava; Martin, Carlos

2017-07-01

Members of the Mycobacterium tuberculosis complex (MTBC) have evolved causing tuberculosis (TB) in different mammalian hosts. MTBC ecotypes have adapted to diverse animal species, with M. bovis being the most common cause of TB in livestock. Cattle-to-human transmission of M. bovis through ingestion of raw milk was common before introduction of the pasteurization process. TB in humans is mainly caused by M. tuberculosis . This bacterium is considered a genetically clonal pathogen that has coevolved with humans due to its ability to manipulate and subvert the immune response. TB is a major public health problem due to airborne person-to-person transmission of M. tuberculosis . The essential yet unanswered question on the natural history of TB is when M. tuberculosis decides to establish latent infection in the host (resambling the lysogenic cycle of lambda phage) or to cause pulmonary disease (comparable to the lytic cycle of lambda phage). In this latter case, M. tuberculosis kills the host with the aim of achieving transmission to new hosts. Combating the TB epidemic requires stopping transmission. M. bovis BCG, the present vaccine against TB, is derived from M. bovis and only protects against disseminated forms of TB. Thus, a priority in TB research is development of new effective vaccines to prevent pulmonary disease. Attenuated vaccines based on M. tuberculosis as MTBVAC are potential candidates that could contribute to break the TB transmission cycle.

Biophoton signal transmission and processing in the brain.

PubMed

Tang, Rendong; Dai, Jiapei

2014-10-05

The transmission and processing of neural information in the nervous system plays a key role in neural functions. It is well accepted that neural communication is mediated by bioelectricity and chemical molecules via the processes called bioelectrical and chemical transmission, respectively. Indeed, the traditional theories seem to give valuable explanations for the basic functions of the nervous system, but difficult to construct general accepted concepts or principles to provide reasonable explanations of higher brain functions and mental activities, such as perception, learning and memory, emotion and consciousness. Therefore, many unanswered questions and debates over the neural encoding and mechanisms of neuronal networks remain. Cell to cell communication by biophotons, also called ultra-weak photon emissions, has been demonstrated in several plants, bacteria and certain animal cells. Recently, both experimental evidence and theoretical speculation have suggested that biophotons may play a potential role in neural signal transmission and processing, contributing to the understanding of the high functions of nervous system. In this paper, we review the relevant experimental findings and discuss the possible underlying mechanisms of biophoton signal transmission and processing in the nervous system. Copyright © 2014 Elsevier B.V. All rights reserved.

Essays on electricity transmission investment and financial transmission rights

NASA Astrophysics Data System (ADS)

Shang, Wenzhuo

The U.S. electric power industry has been going through fundamental restructuring and realignment since the 1990's. Many issues and problems have emerged during the transition, and both economists and engineers have been looking for the solutions fervently. In this dissertation, which consists primarily of three essays, we apply economics theory and techniques to the power industry and address two related issues, transmission investment and financial transmission rights (FTRs). The first essay takes the decentralized perspective and investigates the efficiency attribute of market-based transmission investment under perfect competition. We clarify, for the first time, the nature of the externality created by loop flows that causes transmission investment to be inefficient. Our findings have important implications for better understanding of transmission market design and creating incentives for efficient transmission investment. In the second essay, we define several rules for allocating transmission investment cost within the framework of cooperative game theory. These rules provide fair, stable or efficient cost allocations in theory and are good benchmarks against which the allocation mechanism in practice can be compared and improved upon. In the last essay, we make exploratory efforts in analyzing and assessing empirically the performance of the Midwest independent system operator (MISO) FTR auction market. We reveal some stylized facts about this young market and find that it is not efficient under the risk-neutrality assumption. We also point out and correct the drawbacks in previous related work and suggest about more complete empirical work in future. In all, this dissertation makes both theoretic and empirical analysis of the two hot issues related to the power industry and comes up with findings that have important implications for the development of this industry.

Transmissibility and persistence of oral polio vaccine viruses: implications for the global poliomyelitis eradication initiative.

PubMed

Fine, P E; Carneiro, I A

1999-11-15

The global poliomyelitis eradication initiative has been a tremendous success, with current evidence suggesting that wild poliovirus will cease to circulate anywhere in the world soon after the year 2000. As the goal of wild poliovirus eradication is approached, concern has been raised about the potential for persistent transmission of oral polio vaccine (OPV) viruses, as these viruses are known to revert toward wild-type neurovirulence. This paper has been extracted from a document prepared for the World Health Organization on the implications of OPV transmissibility for the strategy of stopping OPV vaccination after global eradication of wild polioviruses. The authors review the empirical evidence on OPV transmissibility available from household and community transmission studies and from mass-vaccination experiences. They then consider theoretical measures of transmissibility and persistence for wild and OPV viruses (secondary attack rate, basic reproduction number, and critical populations' size), to assess whether transmissibility of OPV viruses is sufficient to allow persistence of these viruses after cessation of vaccination. The findings indicate that OPV viruses could persist under various plausible circumstances, and that this potential should be a major consideration when planning the cessation of OPV vaccination.

AUTOMOTIVE DIESEL MAINTENANCE 2. UNIT XXII, MICHIGAN/CLARK TRANSMISSION--CONVERTER/TRANSMISSION.

ERIC Educational Resources Information Center

Minnesota State Dept. of Education, St. Paul. Div. of Vocational and Technical Education.

THIS MODULE OF A 25-MODULE COURSE IS DESIGNED TO DEVELOP A DETAILED UNDERSTANDING OF A SPECIFIC POWER CONVERTER AND TRANSMISSION USED ON DIESEL POWERED EQUIPMENT. TOPICS ARE A CLOSER LOOK AT THE CONVERTER, CONVERTER ASSEMBLY AND INSTALLATION, TRANSMISSION FUNCTION, AND TRANSMISSION SHIFTING. THE MODULE CONSISTS OF A SELF-INSTRUCTIONAL PROGRAMED…

Power transmission studies for tethered SP-100

NASA Technical Reports Server (NTRS)

Bents, David J.

1988-01-01

The tether and/or transmission line connecting the SP-100 to space station presents some unorthodox challenges in high voltage engineering, power transmission, and distribution. The line, which doubles as a structural element of this unusual spacecraft, will convey HVDC from SP-100 to the platform in low Earth orbit, and environment where the local plasma is sufficient to cause breakdown of exposed conductors at potentials of only a few hundred volts. Its anticipated several years operation, and continuously accumulating exposure to meteoroids and debris, raises an increasing likelihood that mechanical damage, including perforation, will be sustained in service. The present concept employs an array of gas insulated solid wall aluminum coaxial tubes; a conceptual design which showed basic feasibility of the SP-100 powered space station. Practical considerations of launch, deployment and assembly have lead to investigation of reel deployable, dielectric insulated coaxial cables. To be competitive, the dielectric would have to operate reliably in a radiation environment under electrical stresses exceeding 50 kV/cm. The SP-100 transmission line high voltage interfaces are also considered.

Power transmission studies for tethered SP-100

NASA Technical Reports Server (NTRS)

Bents, David J.

1988-01-01

The tether and/or transmission line connecting the SP-100 to Space Station presents some unorthodox challenges in high voltage engineering, power transmission, and distribution. The line, which doubles as a structural element of this unusual spacecraft, will convey HVDC from SP-100 to the platform in low Earth orbit, and environment where the local plasma is sufficient to cause breakdown of exposed conductors at potentials of only a few hundred volts. Its anticipated several years operation, and continuously accumulating exposure to meteoroids and debris, raises an increasing likelihood that mechanical damage, including perforation, will be sustained in service. The present concept employs an array of gas insulated solid wall aluminum coaxial tubes; a conceptual design which showed basic feasibility of the SP-100 powered Space Station. Practical considerations of launch, deployment and assembly have led to investigation of reel deployable, dielectric insulated coaxial cables. To be competitive, the dielectric would have to operate reliably in a radiation environment under electrical stresses exceeding 50 kV/cm. The SP-100 transmission line high voltage interfaces are also considered.

Estimating West Nile virus transmission period in Pennsylvania using an optimized degree-day model.

PubMed

Chen, Shi; Blanford, Justine I; Fleischer, Shelby J; Hutchinson, Michael; Saunders, Michael C; Thomas, Matthew B

2013-07-01

Abstract We provide calibrated degree-day models to predict potential West Nile virus (WNV) transmission periods in Pennsylvania. We begin by following the standard approach of treating the degree-days necessary for the virus to complete the extrinsic incubation period (EIP), and mosquito longevity as constants. This approach failed to adequately explain virus transmission periods based on mosquito surveillance data from 4 locations (Harrisburg, Philadelphia, Pittsburgh, and Williamsport) in Pennsylvania from 2002 to 2008. Allowing the EIP and adult longevity to vary across time and space improved model fit substantially. The calibrated models increase the ability to successfully predict the WNV transmission period in Pennsylvania to 70-80% compared to less than 30% in the uncalibrated model. Model validation showed the optimized models to be robust in 3 of the locations, although still showing errors for Philadelphia. These models and methods could provide useful tools to predict WNV transmission period from surveillance datasets, assess potential WNV risk, and make informed mosquito surveillance strategies.

Adaptation of H9N2 AIV in guinea pigs enables efficient transmission by direct contact and inefficient transmission by respiratory droplets

PubMed Central

Sang, Xiaoyu; Wang, Airong; Ding, Jie; Kong, Huihui; Gao, Xiaolong; Li, Lin; Chai, Tongjie; Li, Yuanguo; Zhang, Kun; Wang, Chengyu; Wan, Zhonghai; Huang, Geng; Wang, Tiecheng; Feng, Na; Zheng, Xuexing; Wang, Hualei; Zhao, Yongkun; Yang, Songtao; Qian, Jun; Hu, Guixue; Gao, Yuwei; Xia, Xianzhu

2015-01-01

H9N2 avian influenza viruses circulate worldwide in poultry and have sporadically infected humans, raising concern whether H9N2 viruses have pandemic potential. Here, we use a guinea pig model to examine whether serial passage results in adaptive viral changes that confer a transmissible phenotype to a wild-type H9N2 virus. After nine serial passages of an H9N2 virus through guinea pigs, productive transmission by direct contact occurred in 2/3 guinea pig pairs. The efficiency of transmission by direct contact increased following the fifteenth passage and occurred in 3/3 guinea pig pairs. In contrast, airborne transmission of the passaged virus was less efficient and occurred in 1/6 guinea pig pairs and 0/6 ferret pairs after the fifteenth passage. Three amino acid substitutions, HA1-Q227P, HA2-D46E, and NP-E434K, were sufficient for contact transmission in guinea pigs (2/3 pairs). The two HA amino acid substitutions enhanced receptor binding to α2,3-linked sialic acid receptors. Additionally, the HA2-D46E substitution increased virus thermostability whereas the NP-E434K mutation enhanced viral RNA polymerase activity in vitro. Our findings suggest that adaptive changes that enhance viral receptor binding, thermostability, and replicative capacity in mammalian cells can collectively enhance the transmissibility of H9N2 AIVs by direct contact in the guinea pig model. PMID:26552719

Successful Interruption of Transmission of Onchocerca volvulus in the Escuintla-Guatemala Focus, Guatemala

PubMed Central

Gonzalez, Rodrigo J.; Cruz-Ortiz, Nancy; Rizzo, Nidia; Richards, Jane; Zea-Flores, Guillermo; Domínguez, Alfredo; Sauerbrey, Mauricio; Catú, Eduardo; Oliva, Orlando; Richards, Frank O.; Lindblade, Kim A.

2009-01-01

Background Elimination of onchocerciasis (river blindness) through mass administration of ivermectin in the six countries in Latin America where it is endemic is considered feasible due to the relatively small size and geographic isolation of endemic foci. We evaluated whether transmission of onchocerciasis has been interrupted in the endemic focus of Escuintla-Guatemala in Guatemala, based on World Health Organization criteria for the certification of elimination of onchocerciasis. Methodology/Principal Findings We conducted evaluations of ocular morbidity and past exposure to Onchocerca volvulus in the human population, while potential vectors (Simulium ochraceum) were captured and tested for O. volvulus DNA; all of the evaluations were carried out in potentially endemic communities (PEC; those with a history of actual or suspected transmission or those currently under semiannual mass treatment with ivermectin) within the focus. The prevalence of microfilariae in the anterior segment of the eye in 329 individuals (≥7 years old, resident in the PEC for at least 5 years) was 0% (one-sided 95% confidence interval [CI] 0–0.9%). The prevalence of antibodies to a recombinant O. volvulus antigen (Ov-16) in 6,432 school children (aged 6 to 12 years old) was 0% (one-sided 95% IC 0–0.05%). Out of a total of 14,099 S. ochraceum tested for O. volvulus DNA, none was positive (95% CI 0–0.01%). The seasonal transmission potential was, therefore, 0 infective stage larvae per person per season. Conclusions/Significance Based on these evaluations, transmission of onchocerciasis in the Escuintla-Guatemala focus has been successfully interrupted. Although this is the second onchocerciasis focus in Latin America to have demonstrated interruption of transmission, it is the first focus with a well-documented history of intense transmission to have eliminated O. volvulus. PMID:19333366

AQUIFER TRANSMISSIVITY

EPA Science Inventory

Evaluation of groundwater resources requires the knowledge of the capacity of aquifers to store and transmit ground water. This requires estimates of key hydraulic parameters, such as the transmissivity, among others. The transmissivity T (m²/sec) is a hydrauli...

Comparative vertical transmission of Rickettsia by Dermacentor variabilis and Amblyomma maculatum

PubMed Central

Harris, Emma K.; Verhoeve, Victoria I.; Banajee, Kaikhushroo H.; Macaluso, Jacqueline A.; Azad, Abdu F.

2017-01-01

The geographical overlap of multiple Rickettsia and tick species coincides with the molecular detection of a variety of rickettsial agents in what may be novel tick hosts. However, little is known concerning transmissibility of rickettsial species by various tick hosts. To examine the vertical transmission potential between select tick and rickettsial species, two sympatric species of ticks, Dermacentor variabilis and Amblyomma maculatum, were exposed to five different rickettsial species, including Rickettsia rickettsii, Rickettsia parkeri, Rickettsia montanensis, Rickettsia amblyommatis, or flea-borne Rickettsia felis. Fitness-related metrics including engorgement weight, egg production index, nutrient index, and egg hatch percentage were then assessed. Subsamples of egg clutches and unfed larvae, nymphs, and adults for each cohort were assessed for transovarial and transstadial transmission of rickettsiae by qPCR. Rickettsial exposure had a minimal fitness effect in D. variabilis and transovarial transmission was observed for all groups except R. rickettsii. In contrast, rickettsial exposure negatively influenced A. maculatum fitness and transovarial transmission of rickettsiae was demonstrated only for R. amblyommatis- and R. parkeri-exposed ticks. Sustained maintenance of rickettsiae via transstadial transmission was diminished from F1 larvae to F1 adults in both tick species. The findings of this study suggest transovarial transmission specificity may not be tick species dependent, and sustained vertical transmission is not common. PMID:28433729

Comparative vertical transmission of Rickettsia by Dermacentor variabilis and Amblyomma maculatum.

PubMed

Harris, Emma K; Verhoeve, Victoria I; Banajee, Kaikhushroo H; Macaluso, Jacqueline A; Azad, Abdu F; Macaluso, Kevin R

2017-06-01

The geographical overlap of multiple Rickettsia and tick species coincides with the molecular detection of a variety of rickettsial agents in what may be novel tick hosts. However, little is known concerning transmissibility of rickettsial species by various tick hosts. To examine the vertical transmission potential between select tick and rickettsial species, two sympatric species of ticks, Dermacentor variabilis and Amblyomma maculatum, were exposed to five different rickettsial species, including Rickettsia rickettsii, Rickettsia parkeri, Rickettsia montanensis, Rickettsia amblyommatis, or flea-borne Rickettsia felis. Fitness-related metrics including engorgement weight, egg production index, nutrient index, and egg hatch percentage were then assessed. Subsamples of egg clutches and unfed larvae, nymphs, and adults for each cohort were assessed for transovarial and transstadial transmission of rickettsiae by qPCR. Rickettsial exposure had a minimal fitness effect in D. variabilis and transovarial transmission was observed for all groups except R. rickettsii. In contrast, rickettsial exposure negatively influenced A. maculatum fitness and transovarial transmission of rickettsiae was demonstrated only for R. amblyommatis- and R. parkeri-exposed ticks. Sustained maintenance of rickettsiae via transstadial transmission was diminished from F 1 larvae to F 1 adults in both tick species. The findings of this study suggest transovarial transmission specificity may not be tick species dependent, and sustained vertical transmission is not common. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) in the region of Saquarema: potential area of visceral leishmaniasis transmission in the state of Rio de Janeiro, Brazil.

PubMed

Brazil, Reginaldo Peçanha; Pontes, Michelle Cristina de Queiroz; Passos, Wagner Lança; Fuzari, Andressa Alencaste; Brazil, Beatriz Gomes

2012-02-01

Lutzomyia longipalpis is the main vector of Leishmania infantum chagasi in the Americas. Phlebotomine captures were conducted during 2008 and 2009 in a rural area endemic for cutaneous leishmaniasis located in the municipality of Saquarema, Rio de Janeiro. Among other species captured, we observed the presence of Lutzomyia longipalpis. This is the first report of the occurrence of Lutzomyia longipalpis in this region, demonstrating the potential risk of visceral leishmaniasis transmission in the coastal area of the State of Rio de Janeiro. Therefore, active vigilance by all municipalities in the area is necessary.

An epidemiological model of virus transmission in salmonid fishes of the Columbia River Basin

USGS Publications Warehouse

Ferguson, Paige F. B.; Breyta, Rachel; Brito, Ilana L.; Kurath, Gael; LaDeau, Shannon L.

2018-01-01

We have developed a dynamic epidemiological model informed by records of viral presence and genotypes to evaluate potential transmission routes maintaining a viral pathogen in economically and culturally important anadromous fish populations. In the Columbia River Basin, infectious hematopoietic necrosis virus (IHNV) causes severe disease, predominantly in juvenile steelhead trout (Oncorhynchus mykiss) and less frequently in Chinook salmon (O. tshawytscha). Mortality events following IHNV infection can be devastating for individual hatchery programs. Despite reports of high local mortality and extensive surveillance efforts, there are questions about how viral transmission is maintained. Modeling this system offers important insights into disease transmission in natural aquatic systems, as well as about the data requirements for generating accurate estimates about transmission routes and infection probabilities. We simulated six scenarios in which testing rates and the relative importance of different transmission routes varied. The simulations demonstrated that the model accurately identified routes of transmission and inferred infection probabilities accurately when there was testing of all cohort-sites. When testing records were incomplete, the model accurately inferred which transmission routes exposed particular cohort-sites but generated biased infection probabilities given exposure. After validating the model and generating guidelines for result interpretation, we applied the model to data from 14 annual cohorts (2000–2013) at 24 focal sites in a sub-region of the Columbia River Basin, the lower Columbia River (LCR), to quantify the relative importance of potential transmission routes in this focal sub-region. We demonstrate that exposure to IHNV via the return migration of adult fish is an important route for maintaining IHNV in the LCR sub-region, and the probability of infection following this exposure was relatively high at 0.16. Although only 1% of

Frequency Selective Properties of Coaxial Transmission Lines Loaded with Combined Artificial Inclusions

PubMed Central

2014-01-01

The properties of a modified coaxial transmission line by periodic inclusions will be discussed. The introduction of split ring resonators, conductor stubs, air gaps, and combination of these gives rise to new frequency selective properties, such as stopband or passband behavior, observable in planar as well as volumetric metamaterial structures. These results envisage new potential applications and implementation of devices in coaxial transmission line technology. PMID:24587748

HVDC Transmission an Outlook and Significance for Pakistani Power Sector

NASA Astrophysics Data System (ADS)

Ahmad, Muhammad; Wang, Zhixin; Wang, Jinjian; Baloach, Mazhar H.; Longxin, Bao; Hua, Qing

2018-04-01

Recently a paradigm shift in the power sector is observed, i.e., countries across the globe have deviated their attention to distributed generation rather than conventional centralized bulk generation. Owing to the above narrative, distributed energy resources e.g., wind and PV have gained the adequate attention of governments and researchers courtesy to their eco-friendly nature. On the contrary, the increased infiltration of distributed generation to the power system has introduced many technical and economical glitches such as long-distance transmission, transmission lines efficiency, control capability and cost etc. To mitigate these complications, the utility of high voltage direct current (HVDC) transmission has emerged as a possible solution. In this context, this paper includes a brief discussion on the fundamentals HVDC and its significance in Pakistani power sector. Furthermore, the potential of distributed energy resources for Pakistan is also the subject matter of this paper, so that significance of HVDC transmission can effectively be deliberated.

Noise transmission through sidewall treatments applicable to twin-engine turboprop aircraft

NASA Technical Reports Server (NTRS)

Grosveld, F. W.

1983-01-01

The noise transmission loss characteristics of the sidewall treatment in the propeller plane of a twin-engine turboprop aircraft are experimentally investigated in the NASA Langley Research Center Transmission Loss Facility. The sound attenuation properties of the individual elements of this treatment are evaluated showing least noise transmission loss in the low frequencies (below 500 Hz) where the excitation levels at the propeller blade passage frequency and the first few harmonics are highest. It is shown that single and double wall resonances play an important role in the noise transmission loss values of the treatment at these low frequencies suggesting that a limp mass with a very low resonance frequency serves better as a trim panel than a trim panel having a high structural stiffness. It is indicated that the window structures might be a potential noise control problem.

Noise transmission through sidewall treatments applicable to twin-engine turboprop aircraft

NASA Astrophysics Data System (ADS)

Grosveld, F. W.

1983-04-01

The noise transmission loss characteristics of the sidewall treatment in the propeller plane of a twin-engine turboprop aircraft are experimentally investigated in the NASA Langley Research Center Transmission Loss Facility. The sound attenuation properties of the individual elements of this treatment are evaluated showing least noise transmission loss in the low frequencies (below 500 Hz) where the excitation levels at the propeller blade passage frequency and the first few harmonics are highest. It is shown that single and double wall resonances play an important role in the noise transmission loss values of the treatment at these low frequencies suggesting that a limp mass with a very low resonance frequency serves better as a trim panel than a trim panel having a high structural stiffness. It is indicated that the window structures might be a potential noise control problem.

Transmission Dynamics of Methicillin-Resistant Staphylococcus aureus in Pigs

PubMed Central

Crombé, Florence; Argudín, M. Angeles; Vanderhaeghen, Wannes; Hermans, Katleen; Haesebrouck, Freddy; Butaye, Patrick

2013-01-01

From the mid-2000s on, numerous studies have shown that methicillin-resistant Staphylococcus aureus (MRSA), renowned as human pathogen, has a reservoir in pigs and other livestock. In Europe and North America, clonal complex (CC) 398 appears to be the predominant lineage involved. Especially worrisome is its capacity to contaminate humans in close contact with affected animals. Indeed, the typical multi-resistant phenotype of MRSA CC398 and its observed ability of easily acquiring genetic material suggests that MRSA CC398 strains with an increased virulence potential may emerge, for which few therapeutic options would remain. This questions the need to implement interventions to control the presence and spread of MRSA CC398 among pigs. MRSA CC398 shows a high but not fully understood transmission potential in the pig population and is able to persist within that population. Although direct contact is probably the main route for MRSA transmission between pigs, also environmental contamination, the presence of other livestock, the herd size, and farm management are factors that may be involved in the dissemination of MRSA CC398. The current review aims at summarizing the research that has so far been done on the transmission dynamics and risk factors for introduction and persistence of MRSA CC398 in farms. PMID:23518663

Staphylococcus aureus infections: transmission within households and the community

PubMed Central

Knox, Justin; Uhlemann, Anne-Catrin; Lowy, Franklin D.

2015-01-01

Staphylococcus aureus , both methicillin susceptible and resistant, are now major community-based pathogens worldwide. The basis for this is multifactorial and includes the emergence of epidemic clones with enhanced virulence, antibiotic resistance, colonization potential, or transmissibility. Household reservoirs of these unique strains are crucial to their success as community-based pathogens. Staphylococci become resident in households, either as colonizers or environmental contaminants, increasing the risk for recurrent infections. Interactions of household members with others in different households or at community sites including schools and daycare facilities play a critical role in the ability of these strains to become endemic. Colonization density at these sites appears to play an important role in facilitating transmission. The integration of research tools including whole genome sequencing, mathematical modeling and social network analysis have provided additional insight into the transmission dynamics of these strains. Thus far, interventions designed to reduce recurrent infections among household members have had limited success, likely due to the multiplicity of potential sources for recolonization. The development of better strategies to reduce the number of household-based infections will depend on greater insight into the different factors that contribute to the success of these uniquely successful epidemic clones of S. aureus. PMID:25864883

Sharps injuries in UK health care: a review of injury rates, viral transmission and potential efficacy of safety devices.

PubMed

Elder, Alexander; Paterson, Caron

2006-12-01

To review the literature on sharps injuries and occupational bloodborne virus transmission in health care in the UK and the worldwide evidence for injury prevention of sharps safety devices. Literature review by online database and Internet resource search. Twenty-four relevant publications were identified regarding UK reported sharps injury rates. UK studies showed as much as a 10-fold difference between injuries reported through standard reporting systems (0.78-5.15 per 100 person-years) and rates estimated from retrospective questionnaires of clinical populations (30-284 per 100 person-years). National surveillance data from England, Wales and Northern Ireland gives a rate of 1.43 known hepatitis C virus or human immunodeficiency virus (HIV) transmissions to health care workers per annum. When extrapolated, this suggests an approximate rate of 0.009 such viral transmissions per 1000 hospital beds per annum. Risk of infection from sources with no risk factors is extremely small (less than one in one million for HIV transmission based on Scottish data). Thirty-one studies on the efficacy of sharps safety devices showed evidence of a reduction in injuries, with the greatest reductions achieved by blunt suture needles and safety cannulae. Although injuries remain common, confirmed viral transmission in the UK has been relatively rare. The degree of under-reporting of sharps injuries may be as much as 10-fold. Safety-engineered devices are likely to be effective at injury reduction.

Subcarrier multiplexing tolerant dispersion transmission system employing optical broadband sources.

PubMed

Grassi, Fulvio; Mora, José; Ortega, Beatriz; Capmany, José

2009-03-16

This paper presents a novel SCM optical transmission system for next-generation WDM-PONs combining broadband optical sources and a Mach-Zehnder interferometric structure. The approach leeds to transport RF signals up to 50 GHz being compatible with RoF systems since a second configuration has been proposed in order to overcome dispersion carrier suppression effect using DSB modulation. The theoretical analysis validates the potentiality of the system also considering the effects of the dispersion slope over the transmission window. (c) 2009 Optical Society of America

Non-iridescent Transmissive Structural Color Filter Featuring Highly Efficient Transmission and High Excitation Purity

PubMed Central

Shrestha, Vivek Raj; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

2014-01-01

Nanostructure based color filtering has been considered an attractive replacement for current colorant pigmentation in the display technologies, in view of its increased efficiencies, ease of fabrication and eco-friendliness. For such structural filtering, iridescence relevant to its angular dependency, which poses a detrimental barrier to the practical development of high performance display and sensing devices, should be mitigated. We report on a non-iridescent transmissive structural color filter, fabricated in a large area of 76.2 × 25.4 mm2, taking advantage of a stack of three etalon resonators in dielectric films based on a high-index cavity in amorphous silicon. The proposed filter features a high transmission above 80%, a high excitation purity of 0.93 and non-iridescence over a range of 160°, exhibiting no significant change in the center wavelength, dominant wavelength and excitation purity, which implies no change in hue and saturation of the output color. The proposed structure may find its potential applications to large-scale display and imaging sensor systems. PMID:24815530

Finite-difference interblock transmissivity for unconfined aquifers and for aquifers having smoothly varying transmissivity

USGS Publications Warehouse

Goode, D.J.; Appel, C.A.

1992-01-01

More accurate alternatives to the widely used harmonic mean interblock transmissivity are proposed for block-centered finite-difference models of ground-water flow in unconfined aquifers and in aquifers having smoothly varying transmissivity. The harmonic mean is the exact interblock transmissivity for steady-state one-dimensional flow with no recharge if the transmissivity is assumed to be spatially uniform over each finite-difference block, changing abruptly at the block interface. However, the harmonic mean may be inferior to other means if transmissivity varies in a continuous or smooth manner between nodes. Alternative interblock transmissivity functions are analytically derived for the case of steady-state one-dimensional flow with no recharge. The second author has previously derived the exact interblock transmissivity, the logarithmic mean, for one-dimensional flow when transmissivity is a linear function of distance in the direction of flow. We show that the logarithmic mean transmissivity is also exact for uniform flow parallel to the direction of changing transmissivity in a two- or three-dimensional model, regardless of grid orientation relative to the flow vector. For the case of horizontal flow in a homogeneous unconfined or water-table aquifer with a horizontal bottom and with areally distributed recharge, the exact interblock transmissivity is the unweighted arithmetic mean of transmissivity at the nodes. This mean also exhibits no grid-orientation effect for unidirectional flow in a two-dimensional model. For horizontal flow in an unconfined aquifer with no recharge where hydraulic conductivity is a linear function of distance in the direction of flow the exact interblock transmissivity is the product of the arithmetic mean saturated thickness and the logarithmic mean hydraulic conductivity. For several hypothetical two- and three-dimensional cases with smoothly varying transmissivity or hydraulic conductivity, the harmonic mean is shown to yield

The potential for zoonotic transmission of Giardia duodenalis and Cryptosporidium spp. from beef and dairy cattle in Ontario, Canada.

PubMed

Dixon, Brent; Parrington, Lorna; Cook, Angela; Pintar, Katarina; Pollari, Frank; Kelton, David; Farber, Jeffrey

2011-01-10

The objective of this study was to compare the occurrence and the genotypes and species of Giardia duodenalis and Cryptosporidium spp. in beef and dairy cattle from farms in the Regional Municipality of Waterloo, Ontario, in an effort to determine the potential for zoonotic transmission from these animals. Pooled manure samples were collected from 45 dairy cattle farms and 30 beef cattle farms. The presence of Giardia cysts and Cryptosporidium oocysts was determined by immunofluorescence microscopy, while nested-PCR and DNA sequencing were used to determine genotypes and species. The overall farm prevalence was very high for both Giardia and Cryptosporidium, and was similar for dairy cattle farms (96 and 64%, respectively) and beef cattle farms (97 and 63%, respectively). However, on dairy cattle farms, G. duodenalis and Cryptosporidium spp. were detected in 44% and 6% of total pooled pen manure samples, respectively, with the occurrence of both parasites being generally higher in calves than in older animals. Most Giardia isolates were identified as either the host-adapted genotype G. duodenalis Assemblage E or the zoonotic Assemblage B. Cryptosporidium parvum and Cryptosporidium andersoni were the most frequently identified species in dairy cattle, while the non-zoonotic species Cryptosporidium ryanae and Cryptosporidium bovis were also found. On beef cattle farms, 72% and 27% of the total pooled pen manure samples were positive for Giardia and Cryptosporidium, respectively, with no obvious correlation with age. All Giardia isolates in beef cattle were identified as G. duodenalis Assemblage E, while all Cryptosporidium isolates were identified by sequence analysis as C. andersoni, although microscopic analyses, and subsequent restriction fragment length polymorphism analyses, indicated that other Cryptosporidium species were also present. The results of this study indicate that although Giardia and Cryptosporidium were identified in a higher overall percentage of

Transmissible gastroenteritis virus; identification of M protein-binding peptide ligands with antiviral and diagnostic potential

USDA-ARS?s Scientific Manuscript database

The membrane (M) protein is one of the major structural proteins of coronavirus particles. In this study, the M protein of transmissible gastroenteritis virus (TGEV) was used to biopan a 12-mer phage display random peptide library. Three phages expressing TGEV-M-binding peptides were identified and ...

Current Knowledge of Leishmania Vectors in Mexico: How Geographic Distributions of Species Relate to Transmission Areas

PubMed Central

González, Camila; Rebollar-Téllez, Eduardo A.; Ibáñez-Bernal, Sergio; Becker-Fauser, Ingeborg; Martínez-Meyer, Enrique; Peterson, A. Townsend; Sánchez-Cordero, Víctor

2011-01-01

Leishmaniases are a group of vector-borne diseases with different clinical manifestations caused by parasites transmitted by sand fly vectors. In Mexico, the sand fly Lutzomyia olmeca olmeca is the only vector proven to transmit the parasite Leishmania mexicana to humans, which causes leishmaniasis. Other vector species with potential medical importance have been obtained, but their geographic distributions and relation to transmission areas have never been assessed. We modeled the ecological niches of nine sand fly species and projected niches to estimate potential distributions by using known occurrences, environmental coverages, and the algorithms GARP and Maxent. All vector species were distributed in areas with known recurrent transmission, except for Lu. diabolica, which appeared to be related only to areas of occasional transmission in northern Mexico. The distribution of Lu. o. olmeca does not overlap with all reported cutaneous leishmaniasis cases, suggesting that Lu. cruciata and Lu. shannoni are likely also involved as primary vectors in those areas. Our study provides useful information of potential risk areas of leishmaniasis transmission in Mexico. PMID:22049037

Application of identifying transmission spheres for spherical surface testing

NASA Astrophysics Data System (ADS)

Han, Christopher B.; Ye, Xin; Li, Xueyuan; Wang, Quanzhao; Tang, Shouhong; Han, Sen

2017-06-01

We developed a new application on Microsoft Foundation Classes (MFC) to identify correct transmission spheres (TS) for Spherical Surface Testing (SST). Spherical surfaces are important optical surfaces, and the wide application and high production rate of spherical surfaces necessitates an accurate and highly reliable measuring device. A Fizeau Interferometer is an appropriate tool for SST due to its subnanometer accuracy. It measures the contour of a spherical surface using a common path, which is insensitive to the surrounding circumstances. The Fizeau Interferometer transmits a wide laser beam, creating interference fringes from re-converging light from the transmission sphere and the test surface. To make a successful measurement, the application calculates and determines the appropriate transmission sphere for the test surface. There are 3 main inputs from the test surfaces that are utilized to determine the optimal sizes and F-numbers of the transmission spheres: (1) the curvatures (concave or convex), (2) the Radii of Curvature (ROC), and (3) the aperture sizes. The application will firstly calculate the F-numbers (i.e. ROC divided by aperture) of the test surface, secondly determine the correct aperture size of a convex surface, thirdly verify that the ROC of the test surface must be shorter than the reference surface's ROC of the transmission sphere, and lastly calculate the percentage of area that the test surface will be measured. However, the amount of interferometers and transmission spheres should be optimized when measuring large spherical surfaces to avoid requiring a large amount of interferometers and transmission spheres for each test surface. Current measuring practices involve tedious and potentially inaccurate calculations. This smart application eliminates human calculation errors, optimizes the selection of transmission spheres (including the least number required) and interferometer sizes, and increases efficiency.

Pellicle transmission uniformity requirements

NASA Astrophysics Data System (ADS)

Brown, Thomas L.; Ito, Kunihiro

1998-12-01

Controlling critical dimensions of devices is a constant battle for the photolithography engineer. Current DUV lithographic process exposure latitude is typically 12 to 15% of the total dose. A third of this exposure latitude budget may be used up by a variable related to masking that has not previously received much attention. The emphasis on pellicle transmission has been focused on increasing the average transmission. Much less, attention has been paid to transmission uniformity. This paper explores the total demand on the photospeed latitude budget, the causes of pellicle transmission nonuniformity and examines reasonable expectations for pellicle performance. Modeling is used to examine how the two primary errors in pellicle manufacturing contribute to nonuniformity in transmission. World-class pellicle transmission uniformity standards are discussed and a comparison made between specifications of other components in the photolithographic process. Specifications for other materials or parameters are used as benchmarks to develop a proposed industry standard for pellicle transmission uniformity.

Simulation of action potential propagation in plants.

PubMed

Sukhov, Vladimir; Nerush, Vladimir; Orlova, Lyubov; Vodeneev, Vladimir

2011-12-21

Action potential is considered to be one of the primary responses of a plant to action of various environmental factors. Understanding plant action potential propagation mechanisms requires experimental investigation and simulation; however, a detailed mathematical model of plant electrical signal transmission is absent. Here, the mathematical model of action potential propagation in plants has been worked out. The model is a two-dimensional system of excitable cells; each of them is electrically coupled with four neighboring ones. Ion diffusion between excitable cell apoplast areas is also taken into account. The action potential generation in a single cell has been described on the basis of our previous model. The model simulates active and passive signal transmission well enough. It has been used to analyze theoretically the influence of cell to cell electrical conductivity and H(+)-ATPase activity on the signal transmission in plants. An increase in cell to cell electrical conductivity has been shown to stimulate an increase in the length constant, the action potential propagation velocity and the temperature threshold, while the membrane potential threshold being weakly changed. The growth of H(+)-ATPase activity has been found to induce the increase of temperature and membrane potential thresholds and the reduction of the length constant and the action potential propagation velocity. Copyright © 2011 Elsevier Ltd. All rights reserved.

Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission.

PubMed

Ordax, Mónica; Piquer-Salcedo, Jaime E; Santander, Ricardo D; Sabater-Muñoz, Beatriz; Biosca, Elena G; López, María M; Marco-Noales, Ester

2015-01-01

Monitoring the ability of bacterial plant pathogens to survive in insects is required for elucidating unknown aspects of their epidemiology and for designing appropriate control strategies. Erwinia amylovora is a plant pathogenic bacterium that causes fire blight, a devastating disease in apple and pear commercial orchards. Studies on fire blight spread by insects have mainly focused on pollinating agents, such as honeybees. However, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae), one of the most damaging fruit pests worldwide, is also common in pome fruit orchards. The main objective of the study was to investigate whether E. amylovora can survive and be transmitted by the medfly. Our experimental results show: i) E. amylovora can survive for at least 8 days inside the digestive tract of the medfly and until 28 days on its external surface, and ii) medflies are able to transmit the bacteria from inoculated apples to both detached shoots and pear plants, being the pathogen recovered from lesions in both cases. This is the first report on E. amylovora internalization and survival in/on C. capitata, as well as the experimental transmission of the fire blight pathogen by this insect. Our results suggest that medfly can act as a potential vector for E. amylovora, and expand our knowledge on the possible role of these and other insects in its life cycle.

Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission

PubMed Central

Ordax, Mónica; Piquer-Salcedo, Jaime E.; Santander, Ricardo D.; Sabater-Muñoz, Beatriz; Biosca, Elena G.; López, María M.; Marco-Noales, Ester

2015-01-01

Monitoring the ability of bacterial plant pathogens to survive in insects is required for elucidating unknown aspects of their epidemiology and for designing appropriate control strategies. Erwinia amylovora is a plant pathogenic bacterium that causes fire blight, a devastating disease in apple and pear commercial orchards. Studies on fire blight spread by insects have mainly focused on pollinating agents, such as honeybees. However, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae), one of the most damaging fruit pests worldwide, is also common in pome fruit orchards. The main objective of the study was to investigate whether E. amylovora can survive and be transmitted by the medfly. Our experimental results show: i) E. amylovora can survive for at least 8 days inside the digestive tract of the medfly and until 28 days on its external surface, and ii) medflies are able to transmit the bacteria from inoculated apples to both detached shoots and pear plants, being the pathogen recovered from lesions in both cases. This is the first report on E. amylovora internalization and survival in/on C. capitata, as well as the experimental transmission of the fire blight pathogen by this insect. Our results suggest that medfly can act as a potential vector for E. amylovora, and expand our knowledge on the possible role of these and other insects in its life cycle. PMID:25978369

Multiplayer games and HIV transmission via casual encounters.

PubMed

Tully, Stephen; Cojocaru, Monica-Gabriela; Bauch, Chris T

2017-04-01

Population transmission models have been helpful in studying the spread of HIV. They assess changes made at the population level for different intervention strategies. To further understand how individual changes affect the population as a whole, game-theoretical models are used to quantify the decision-making process. Investigating multiplayer nonlinear games that model HIV transmission represents a unique approach in epidemiological research. We present here 2-player and multiplayer noncooperative games where players are defined by HIV status and age and may engage in casual (sexual) encounters. The games are modelled as generalized Nash games with shared constraints, which is completely novel in the context of our applied problem. Each player's HIV status is known to potential partners, and players have personal preferences ranked via utility values of unprotected and protected sex outcomes. We model a player's strategy as their probability of being engaged in a casual unprotected sex encounter (USE), which may lead to HIV transmission; however, we do not incorporate a transmission model here. We study the sensitivity of Nash strategies with respect to varying preference rankings, and the impact of a prophylactic vaccine introduced in players of youngest age groups. We also study the effect of these changes on the overall increase in infection level, as well as the effects that a potential prophylactic treatment may have on age-stratified groups of players. We conclude that the biggest impacts on increasing the infection levels in the overall population are given by the variation in the utilities assigned to individuals for unprotected sex with others of opposite HIV status, while the introduction of a prophylactic vaccine in youngest age group (15-20 yr olds) slows down the increase in HIV infection.

Effects of channel blocking on information transmission and energy efficiency in squid giant axons.

PubMed

Liu, Yujiang; Yue, Yuan; Yu, Yuguo; Liu, Liwei; Yu, Lianchun

2018-04-01

Action potentials are the information carriers of neural systems. The generation of action potentials involves the cooperative opening and closing of sodium and potassium channels. This process is metabolically expensive because the ions flowing through open channels need to be restored to maintain concentration gradients of these ions. Toxins like tetraethylammonium can block working ion channels, thus affecting the function and energy cost of neurons. In this paper, by computer simulation of the Hodgkin-Huxley neuron model, we studied the effects of channel blocking with toxins on the information transmission and energy efficiency in squid giant axons. We found that gradually blocking sodium channels will sequentially maximize the information transmission and energy efficiency of the axons, whereas moderate blocking of potassium channels will have little impact on the information transmission and will decrease the energy efficiency. Heavy blocking of potassium channels will cause self-sustained oscillation of membrane potentials. Simultaneously blocking sodium and potassium channels with the same ratio increases both information transmission and energy efficiency. Our results are in line with previous studies suggesting that information processing capacity and energy efficiency can be maximized by regulating the number of active ion channels, and this indicates a viable avenue for future experimentation.

Chronic Wasting Disease: Transmission Mechanisms and the Possibility of Harvest Management

PubMed Central

Potapov, Alex; Merrill, Evelyn; Pybus, Margo; Lewis, Mark A.

2016-01-01

We develop a model of CWD management by nonselective deer harvest, currently the most feasible approach available for managing CWD in wild populations. We use the model to explore the effects of 6 common harvest strategies on disease prevalence and to identify potential optimal harvest policies for reducing disease prevalence without population collapse. The model includes 4 deer categories (juveniles, adult females, younger adult males, older adult males) that may be harvested at different rates, a food-based carrying capacity, which influences juvenile survival but not adult reproduction or survival, and seasonal force of infection terms for each deer category under differing frequency-dependent transmission dynamics resulting from environmental and direct contact mechanisms. Numerical experiments show that the interval of transmission coefficients β where the disease can be controlled is generally narrow and efficiency of a harvest policy to reduce disease prevalence depends crucially on the details of the disease transmission mechanism, in particular on the intensity of disease transmission to juveniles and the potential differences in the behavior of older and younger males that influence contact rates. Optimal harvest policy to minimize disease prevalence for each of the assumed transmission mechanisms is shown to depend on harvest intensity. Across mechanisms, a harvest that focuses on antlered deer, without distinguishing between age classes reduces disease prevalence most consistently, whereas distinguishing between young and older antlered deer produces higher uncertainty in the harvest effects on disease prevalence. Our results show that, despite uncertainties, a modelling approach can determine classes of harvest strategy that are most likely to be effective in combatting CWD. PMID:26963921

Twisted light transmission over 143 km

PubMed Central

Krenn, Mario; Handsteiner, Johannes; Fink, Matthias; Fickler, Robert; Ursin, Rupert; Zeilinger, Anton

2016-01-01

Spatial modes of light can potentially carry a vast amount of information, making them promising candidates for both classical and quantum communication. However, the distribution of such modes over large distances remains difficult. Intermodal coupling complicates their use with common fibers, whereas free-space transmission is thought to be strongly influenced by atmospheric turbulence. Here, we show the transmission of orbital angular momentum modes of light over a distance of 143 km between two Canary Islands, which is 50× greater than the maximum distance achieved previously. As a demonstration of the transmission quality, we use superpositions of these modes to encode a short message. At the receiver, an artificial neural network is used for distinguishing between the different twisted light superpositions. The algorithm is able to identify different mode superpositions with an accuracy of more than 80% up to the third mode order and decode the transmitted message with an error rate of 8.33%. Using our data, we estimate that the distribution of orbital angular momentum entanglement over more than 100 km of free space is feasible. Moreover, the quality of our free-space link can be further improved by the use of state-of-the-art adaptive optics systems. PMID:27856744

Twisted light transmission over 143 km

NASA Astrophysics Data System (ADS)

Krenn, Mario; Handsteiner, Johannes; Fink, Matthias; Fickler, Robert; Ursin, Rupert; Malik, Mehul; Zeilinger, Anton

2016-11-01

Spatial modes of light can potentially carry a vast amount of information, making them promising candidates for both classical and quantum communication. However, the distribution of such modes over large distances remains difficult. Intermodal coupling complicates their use with common fibers, whereas free-space transmission is thought to be strongly influenced by atmospheric turbulence. Here, we show the transmission of orbital angular momentum modes of light over a distance of 143 km between two Canary Islands, which is 50× greater than the maximum distance achieved previously. As a demonstration of the transmission quality, we use superpositions of these modes to encode a short message. At the receiver, an artificial neural network is used for distinguishing between the different twisted light superpositions. The algorithm is able to identify different mode superpositions with an accuracy of more than 80% up to the third mode order and decode the transmitted message with an error rate of 8.33%. Using our data, we estimate that the distribution of orbital angular momentum entanglement over more than 100 km of free space is feasible. Moreover, the quality of our free-space link can be further improved by the use of state-of-the-art adaptive optics systems.

Twisted light transmission over 143 km.

PubMed

Krenn, Mario; Handsteiner, Johannes; Fink, Matthias; Fickler, Robert; Ursin, Rupert; Malik, Mehul; Zeilinger, Anton

2016-11-29

Spatial modes of light can potentially carry a vast amount of information, making them promising candidates for both classical and quantum communication. However, the distribution of such modes over large distances remains difficult. Intermodal coupling complicates their use with common fibers, whereas free-space transmission is thought to be strongly influenced by atmospheric turbulence. Here, we show the transmission of orbital angular momentum modes of light over a distance of 143 km between two Canary Islands, which is 50× greater than the maximum distance achieved previously. As a demonstration of the transmission quality, we use superpositions of these modes to encode a short message. At the receiver, an artificial neural network is used for distinguishing between the different twisted light superpositions. The algorithm is able to identify different mode superpositions with an accuracy of more than 80% up to the third mode order and decode the transmitted message with an error rate of 8.33%. Using our data, we estimate that the distribution of orbital angular momentum entanglement over more than 100 km of free space is feasible. Moreover, the quality of our free-space link can be further improved by the use of state-of-the-art adaptive optics systems.

Adult vector control, mosquito ecology and malaria transmission

PubMed Central

Brady, Oliver J.; Godfray, H. Charles J.; Tatem, Andrew J.; Gething, Peter W.; Cohen, Justin M.; McKenzie, F. Ellis; Alex Perkins, T.; Reiner, Robert C.; Tusting, Lucy S.; Scott, Thomas W.; Lindsay, Steven W.; Hay, Simon I.; Smith, David L.

2015-01-01

Background Standard advice regarding vector control is to prefer interventions that reduce the lifespan of adult mosquitoes. The basis for this advice is a decades-old sensitivity analysis of ‘vectorial capacity’, a concept relevant for most malaria transmission models and based solely on adult mosquito population dynamics. Recent advances in micro-simulation models offer an opportunity to expand the theory of vectorial capacity to include both adult and juvenile mosquito stages in the model. Methods In this study we revisit arguments about transmission and its sensitivity to mosquito bionomic parameters using an elasticity analysis of developed formulations of vectorial capacity. Results We show that reducing adult survival has effects on both adult and juvenile population size, which are significant for transmission and not accounted for in traditional formulations of vectorial capacity. The elasticity of these effects is dependent on various mosquito population parameters, which we explore. Overall, control is most sensitive to methods that affect adult mosquito mortality rates, followed by blood feeding frequency, human blood feeding habit, and lastly, to adult mosquito population density. Conclusions These results emphasise more strongly than ever the sensitivity of transmission to adult mosquito mortality, but also suggest the high potential of combinations of interventions including larval source management. This must be done with caution, however, as policy requires a more careful consideration of costs, operational difficulties and policy goals in relation to baseline transmission. PMID:25733562

Adult vector control, mosquito ecology and malaria transmission.

PubMed

Brady, Oliver J; Godfray, H Charles J; Tatem, Andrew J; Gething, Peter W; Cohen, Justin M; McKenzie, F Ellis; Alex Perkins, T; Reiner, Robert C; Tusting, Lucy S; Scott, Thomas W; Lindsay, Steven W; Hay, Simon I; Smith, David L

2015-03-01

Standard advice regarding vector control is to prefer interventions that reduce the lifespan of adult mosquitoes. The basis for this advice is a decades-old sensitivity analysis of 'vectorial capacity', a concept relevant for most malaria transmission models and based solely on adult mosquito population dynamics. Recent advances in micro-simulation models offer an opportunity to expand the theory of vectorial capacity to include both adult and juvenile mosquito stages in the model. In this study we revisit arguments about transmission and its sensitivity to mosquito bionomic parameters using an elasticity analysis of developed formulations of vectorial capacity. We show that reducing adult survival has effects on both adult and juvenile population size, which are significant for transmission and not accounted for in traditional formulations of vectorial capacity. The elasticity of these effects is dependent on various mosquito population parameters, which we explore. Overall, control is most sensitive to methods that affect adult mosquito mortality rates, followed by blood feeding frequency, human blood feeding habit, and lastly, to adult mosquito population density. These results emphasise more strongly than ever the sensitivity of transmission to adult mosquito mortality, but also suggest the high potential of combinations of interventions including larval source management. This must be done with caution, however, as policy requires a more careful consideration of costs, operational difficulties and policy goals in relation to baseline transmission. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.

Molecular characterisation of Galba truncatula, Lymnaea neotropica and L. schirazensis from Cajamarca, Peru and their potential role in transmission of human and animal fascioliasis

PubMed Central

2012-01-01

Background Human and animal fascioliasis is emerging in many world regions, among which Andean countries constitute the largest regional hot spot and Peru the country presenting more human endemic areas. A survey was undertaken on the lymnaeid snails inhabiting the hyperendemic area of Cajamarca, where human prevalences are the highest known among the areas presenting a "valley transmission pattern", to establish which species are present, genetically characterise their populations by comparison with other human endemic areas, and discuss which ones have transmission capacity and their potential implications with human and animal infection. Methods Therefore, ribosomal DNA ITS-2 and ITS-1, and mitochondrial DNA 16S and cox1 were sequenced by the dideoxy chain-termination method. Results Results indicate the presence of three, morphologically similar, small lymnaeid species belonging to the Galba/Fossaria group: Galba truncatula, Lymnaea neotropica and L. schirazensis. Only one combined haplotype for each species was found. The ITS-1, 16S and cox1 haplotypes of G. truncatula are new. No new haplotypes were found in the other two species. This scenario changes previous knowledge, in which only L. viator (= L. viatrix) was mentioned. Galba truncatula appears to be the most abundant, with high population densities and evident anthropophyly including usual presence in human neighbourhood. Infection by Fasciola hepatica larval stages were molecularly confirmed in two populations of this species. The nearness between G. truncatula populations presenting liver fluke infection and both human settings and schools for children, together with the absence of populations of other lymnaeid species in the locality, suggest a direct relationship with human infection. Conclusions The geographical overlap of three lymnaeid species poses problems for epidemiological studies and control action. First, a problem in classifying lymnaeid specimens in both field and laboratory activities

Increasing incidence of malaria in the Negro River basin, Brazilian Amazon.

PubMed

Cabral, A C; Fé, N F; Suárez-Mutis, M C; Bóia, M N; Carvalho-Costa, F A

2010-08-01

Malaria in Brazil is virtually restricted to the Amazon Region, where it has a heterogeneous geographic distribution. We reviewed secondary data in order to describe the regional and temporal distribution of 8018 malaria cases seen between 2003 and 2007 in Santa Isabel do Rio Negro, a municipality in the northwest Brazilian Amazon. A significant rise in malaria incidence, mainly in the Yanomami Indian reservation, was observed during this time. Anopheline breeding sites were also mapped and entomological data were obtained through the capture of larval and adult mosquitoes. Thirty-three potential breeding sites were identified in the urban and periurban areas, 28 of which were positive for anopheline larvae. Anopheles darlingi specimens were captured in both intra- and peridomicile locations in the urban areas. Demographic data were also assessed via a sectional survey, revealing that the majority of dwellings were vulnerable to mosquitoes. This study suggests that urban and periurban areas of this municipality are highly susceptible to epidemic malaria, which is endemic in the Yanomami Indian reservation near the city. In addition, transmission can be perpetuated autochthonously in the urban area, drawing attention to the continuous need for preventative measures such as controlling adult and aquatic stages of mosquitoes and improving housing.

Monitoring and modelling of pumping-induced self-potentials for transmissivity estimation within a heterogeneous confined aquifer

NASA Astrophysics Data System (ADS)

DesRoches, Aaron J.; Butler, Karl E.

2016-12-01

Variations in self-potentials (SP) measured at surface during pumping of a heterogeneous confined fractured rock aquifer have been monitored and modelled in order to investigate capabilities and limitations of SP methods in estimating aquifer hydraulic properties. SP variations were recorded around a pumping well using an irregular grid of 31 non-polarizing Pb-PbCl2 that were referenced to a remote electrode and connected to a commercial multiplexer and digitizer/data logger through a passive lowpass filter on each channel. The lowpass filter reduced noise by a factor of 10 compared to levels obtained using the data logger's integration-based sampling method for powerline noise suppression alone. SP signals showed a linear relationship with water levels observed in the pumping and monitoring wells over the pumping period, with an apparent electrokinetic coupling coefficient of -3.4 mV · m-1. Following recent developments in SP methodology, variability of the SP response between different electrodes is taken as a proxy for lateral variations in hydraulic head within the aquifer and used to infer lateral variations in the aquifer's apparent transmissivity. In order to demonstrate the viability of this approach, SP is modelled numerically to determine its sensitivity to (i) lateral variations in the hydraulic conductivity of the confined aquifer and (ii) the electrical conductivity of the confining layer and conductive well casing. In all cases, SP simulated on the surface still varies linearly with hydraulic head modelled at the base on the confining layer although the apparent coupling coefficient changes to varying degrees. Using the linear relationship observed in the field, drawdown curves were inferred for each electrode location using SP variations observed over the duration of the pumping period. Transmissivity estimates, obtained by fitting the Theis model to inferred drawdown curves at all 31 electrodes, fell within a narrow range of (2.0-4.2) × 10-3 m2 �

Downhole transmission system

DOEpatents

Hall, David R [Provo, UT; Fox, Joe [Spanish Fork, UT

2008-01-15

A transmission system in a downhole component comprises a data transmission element in both ends of the downhole component. Each data transmission element houses an electrically conducting coil in a MCEI circular trough. An electrical conductor connects both the transmission elements. The electrical conductor comprises at least three electrically conductive elements insulated from each other. In the preferred embodiment the electrical conductor comprises an electrically conducting outer shield, an electrically conducting inner shield and an electrical conducting core. In some embodiments of the present invention, the electrical conductor comprises an electrically insulating jacket. In other embodiments, the electrical conductor comprises a pair of twisted wires. In some embodiments, the electrical conductor comprises semi-conductive material.

Printed circuit dispersive transmission line

DOEpatents

Ikezi, H.; Lin-Liu, Y.R.; DeGrassie, J.S.

1991-08-27

A printed circuit dispersive transmission line structure is disclosed comprising an insulator, a ground plane formed on one surface of the insulator, a first transmission line formed on a second surface of the insulator, and a second transmission line also formed on the second surface of the insulator and of longer length than the first transmission line and periodically intersecting the first transmission line. In a preferred embodiment, the transmission line structure exhibits highly dispersive characteristics by designing the length of one of the transmission line between two adjacent periodic intersections to be longer than the other. 5 figures.

Printed circuit dispersive transmission line

DOEpatents

Ikezi, Hiroyuki; Lin-Liu, Yuh-Ren; DeGrassie, John S.

1991-01-01

A printed circuit dispersive transmission line structure is disclosed comprising an insulator, a ground plane formed on one surface of the insulator, a first transmission line formed on a second surface of the insulator, and a second transmission line also formed on the second surface of the insulator and of longer length than the first transmission line and periodically intersecting the first transmission line. In a preferred embodiment, the transmission line structure exhibits highly dispersive characteristics by designing the length of one of the transmission line between two adjacent periodic intersections to be longer than the other.

The Complex Relationship between Weather and Dengue Virus Transmission in Thailand

PubMed Central

Campbell, Karen M.; Lin, C. D.; Iamsirithaworn, Sopon; Scott, Thomas W.

2013-01-01

Using a novel analytical approach, weather dynamics and seasonal dengue virus transmission cycles were profiled for each Thailand province, 1983–2001, using monthly assessments of cases, temperature, humidity, and rainfall. We observed systematic differences in the structure of seasonal transmission cycles of different magnitude, the role of weather in regulating seasonal cycles, necessary versus optimal transmission “weather-space,” basis of large epidemics, and predictive indicators that estimate risk. Larger epidemics begin earlier, develop faster, and are predicted at Onset change-point when case counts are low. Temperature defines a viable range for transmission; humidity amplifies the potential within that range. This duality is central to transmission. Eighty percent of 1.2 million severe dengue cases occurred when mean temperature was 27–29.5°C and mean humidity was > 75%. Interventions are most effective when applied early. Most cases occur near Peak, yet small reductions at Onset can substantially reduce epidemic magnitude. Monitoring the Quiet-Phase is fundamental in effectively targeting interventions pre-emptively. PMID:23958906

Asbestos exposure among transmission mechanics in automotive repair shops.

PubMed

Salazar, Natalia; Cely-García, María Fernanda; Breysse, Patrick N; Ramos-Bonilla, Juan Pablo

2015-04-01

Asbestos has been used in a broad variety of industrial products, including clutch discs of the transmission system of vehicles. Studies conducted in high-income countries that have analyzed personal asbestos exposures of transmission mechanics have concluded that these workers are exposed to asbestos concentrations in compliance with the US Occupational Safety and Health Administration (US OSHA) occupational standards. Clutch facings are the friction component of clutch discs. If clutch facings are sold separated from the support, they require manipulation before installation in the vehicle. The manipulation of asbestos containing clutch facings is performed by a group of mechanics known as riveters, and includes drilling, countersinking, riveting, sanding, and occasionally grinding, tasks that can potentially release asbestos fibers, exposing the mechanics. These manipulation activities are not reported in studies conducted in high-income countries. This study analyzes personal asbestos exposures of transmission mechanics that manipulate clutch facings. Air sampling campaigns in two transmission repair shops (TRS) were conducted in November 2012 and July 2013 in Bogotá, Colombia. Four workers employed in these TRS were sampled (i.e. three riveters and one supervisor). Personal samples (n = 39), short-term personal samples (n = 49), area samples (n = 52), blank samples (n = 8), and background samples (n = 2) were collected in both TRS during 3-5 consecutive days, following US National Institute for Occupational Safety and Health (US NIOSH) methods 7400 and 7402. Asbestos samples were analyzed by an American Industrial Hygiene Association accredited laboratory. On at least one of the days sampled, all riveters were exposed to asbestos concentrations that exceeded the US OSHA permissible exposure limit or the Colombian permissible limit value. Additionally, from the forty-seven 30-min short-term personal samples collected, two (4.3%) exceeded the US OSHA excursion

Heterosexual Transmission of Subtype C HIV-1 Selects Consensus-Like Variants without Increased Replicative Capacity or Interferon-α Resistance

PubMed Central

Fenton-May, Angharad E.; Dilernia, Dario A.; Kilembe, William; Allen, Susan A.; Borrow, Persephone; Hunter, Eric

2015-01-01

Heterosexual transmission of HIV-1 is characterized by a genetic bottleneck that selects a single viral variant, the transmitted/founder (TF), during most transmission events. To assess viral characteristics influencing HIV-1 transmission, we sequenced 167 near full-length viral genomes and generated 40 infectious molecular clones (IMC) including TF variants and multiple non-transmitted (NT) HIV-1 subtype C variants from six linked heterosexual transmission pairs near the time of transmission. Consensus-like genomes sensitive to donor antibodies were selected for during transmission in these six transmission pairs. However, TF variants did not demonstrate increased viral fitness in terms of particle infectivity or viral replicative capacity in activated peripheral blood mononuclear cells (PBMC) and monocyte-derived dendritic cells (MDDC). In addition, resistance of the TF variant to the antiviral effects of interferon-α (IFN-α) was not significantly different from that of non-transmitted variants from the same transmission pair. Thus neither in vitro viral replicative capacity nor IFN-α resistance discriminated the transmission potential of viruses in the quasispecies of these chronically infected individuals. However, our findings support the hypothesis that within-host evolution of HIV-1 in response to adaptive immune responses reduces viral transmission potential. PMID:26378795

Modeling effective transmission pathways and control of the world's most successful parasite.

PubMed

Turner, Matthew; Lenhart, Suzanne; Rosenthal, Benjamin; Zhao, Xiaopeng

2013-06-01

Toxoplasma gondii(T. gondii) is a single-celled, intracellular protozoan responsible for the disease toxoplasmosis. The parasite is prevalent worldwide, and it infects all warm-blooded vertebrates. Consumption of meats in which this parasite has encysted confers risk of infection to people and other animals, as does ingestion of water or foods contaminated with environmentally resistant oocysts excreted by cats. Vertical transmission (from mother to offspring) is also possible, leading to disease risk and contributing additional means of ensuring perpetuation of transmission. In this work, we adopt a differential equation model to investigate the effective transmission pathways of T. gondii, as well as potential control mechanisms. Detailed analyses are carried out to examine the significance of transmission routes, virulence, vertical transmission, parasite-induced changes in host behavior, and controls based on vaccination and harvesting. Modeling and analysis efforts may shed insights into understanding the complex life cycle of T. gondii. Copyright © 2013 Elsevier Inc. All rights reserved.

Uncovering the transmission dynamics of Plasmodium vivax using population genetics

PubMed Central

Barry, Alyssa E.; Waltmann, Andreea; Koepfli, Cristian; Barnadas, Celine; Mueller, Ivo

2015-01-01

Population genetic analysis of malaria parasites has the power to reveal key insights into malaria epidemiology and transmission dynamics with the potential to deliver tools to support control and elimination efforts. Analyses of parasite genetic diversity have suggested that Plasmodium vivax populations are more genetically diverse and less structured than those of Plasmodium falciparum indicating that P. vivax may be a more ancient parasite of humans and/or less susceptible to population bottlenecks, as well as more efficient at disseminating its genes. These population genetic insights into P. vivax transmission dynamics provide an explanation for its relative resilience to control efforts. Here, we describe current knowledge on P. vivax population genetic structure, its relevance to understanding transmission patterns and relapse and how this information can inform malaria control and elimination programmes. PMID:25891915

An Exploration of Professional Culture Differentials and Their Potential Impact on the Information Assurance Component of Optical Transmission Networks Design

ERIC Educational Resources Information Center

Cuthrell, Michael Gerard

2011-01-01

Optical transmission networks are an integral component of the critical infrastructures for many nations. Many people believe that optical transmission networks are impenetrable. In actuality, these networks possess weaknesses that can be exploited to bring about harm. An emerging Information Assurance (IA) industry has as its goals: to…

Drivers of Tuberculosis Transmission.

PubMed

Mathema, Barun; Andrews, Jason R; Cohen, Ted; Borgdorff, Martien W; Behr, Marcel; Glynn, Judith R; Rustomjee, Roxana; Silk, Benjamin J; Wood, Robin

2017-11-03

Measuring tuberculosis transmission is exceedingly difficult, given the remarkable variability in the timing of clinical disease after Mycobacterium tuberculosis infection; incident disease can result from either a recent (ie, weeks to months) or a remote (ie, several years to decades) infection event. Although we cannot identify with certainty the timing and location of tuberculosis transmission for individuals, approaches for estimating the individual probability of recent transmission and for estimating the fraction of tuberculosis cases due to recent transmission in populations have been developed. Data used to estimate the probable burden of recent transmission include tuberculosis case notifications in young children and trends in tuberculin skin test and interferon γ-release assays. More recently, M. tuberculosis whole-genome sequencing has been used to estimate population levels of recent transmission, identify the distribution of specific strains within communities, and decipher chains of transmission among culture-positive tuberculosis cases. The factors that drive the transmission of tuberculosis in communities depend on the burden of prevalent tuberculosis; the ways in which individuals live, work, and interact (eg, congregate settings); and the capacity of healthcare and public health systems to identify and effectively treat individuals with infectious forms of tuberculosis. Here we provide an overview of these factors, describe tools for measurement of ongoing transmission, and highlight knowledge gaps that must be addressed. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Helminth-infected patients with malaria: a low profile transmission hub?

PubMed

Nacher, Mathieu

2012-11-15

Eclipsed by the debates about malaria incidence and severity in individual patients, malaria transmission in helminth-infected persons has so far received very little attention. Studies in humans have shown increased malaria incidence and prevalence, and a trend for a reduction of symptoms in patients with malaria. This suggests that such patients could possibly be less likely to seek treatment thus carrying malaria parasites and their gametocytes for longer durations, therefore, being a greater potential source of transmission. In addition, in humans, a study showed increased gametocyte carriage, and in an animal model of helminth-malaria co-infection, there was increased malaria transmission. These elements converge towards the hypothesis that patients co-infected with worms and malaria may represent a hub of malaria transmission. The test of this hypothesis requires verifying, in different epidemiological settings, that helminth-infected patients have more gametocytes, that they have less symptomatic malaria and longer-lasting infections, and that they are more attractive for the vectors. The negative outcome in one setting of one of the above aspects does not necessarily mean that the other two aspects may suffice to increase transmission. If it is verified that patients co-infected by worms and malaria could be a transmission hub, this would be an interesting piece of strategic information in the context of the spread of anti-malarial resistance and the malaria eradication attempts.

Automated manual transmission clutch controller

DOEpatents

Lawrie, Robert E.; Reed, Jr., Richard G.; Rausen, David J.

1999-11-30

A powertrain system for a hybrid vehicle. The hybrid vehicle includes a heat engine, such as a diesel engine, and an electric machine, which operates as both an electric motor and an alternator, to power the vehicle. The hybrid vehicle also includes a manual-style transmission configured to operate as an automatic transmission from the perspective of the driver. The engine and the electric machine drive an input shaft which in turn drives an output shaft of the transmission. In addition to driving the transmission, the electric machine regulates the speed of the input shaft in order to synchronize the input shaft during either an upshift or downshift of the transmission by either decreasing or increasing the speed of the input shaft. When decreasing the speed of the input shaft, the electric motor functions as an alternator to produce electrical energy which may be stored by a storage device. Operation of the transmission is controlled by a transmission controller which receives input signals and generates output signals to control shift and clutch motors to effect smooth launch, upshift shifts, and downshifts of the transmission, so that the transmission functions substantially as an automatic transmission from the perspective of the driver, while internally substantially functioning as a manual transmission.

Molecular Markers for Interspecies Transmission of Avian Influenza Viruses in Mammalian Hosts

PubMed Central

Lee, Taehyung

2017-01-01

In the last decade, a wide range of avian influenza viruses (AIVs) have infected various mammalian hosts and continuously threaten both human and animal health. It is a result of overcoming the inter-species barrier which is mostly associated with gene reassortment and accumulation of mutations in their gene segments. Several recent studies have shed insights into the phenotypic and genetic changes that are involved in the interspecies transmission of AIVs. These studies have a major focus on transmission from avian to mammalian species due to the high zoonotic potential of the viruses. As more mammalian species have been infected with these viruses, there is higher risk of genetic evolution of these viruses that may lead to the next human pandemic which represents and raises public health concern. Thus, understanding the mechanism of interspecies transmission and molecular determinants through which the emerging AIVs can acquire the ability to transmit to humans and other mammals is an important key in evaluating the potential risk caused by AIVs among humans. Here, we summarize previous and recent studies on molecular markers that are specifically involved in the transmission of avian-derived influenza viruses to various mammalian hosts including humans, pigs, horses, dogs, and marine mammals. PMID:29236050

Models of Intergenerational and Transgenerational Transmission of Risk for Psychopathology in Mice

PubMed Central

Klengel, Torsten; Dias, Brian G; Ressler, Kerry J

2016-01-01

Trajectories toward risk or resilience in psychiatric disorders are influenced by acquired and inherited factors. More recently, evidence from rodent studies suggest that acquired risk factors can be transmitted through non-genomic, epigenetic mechanisms to subsequent generations, potentially contributing to a cycle of disease and disease risk. Here, we review examples of transmission of environmental factors across generations and illustrate the difference between behavioral transmission and epigenetic inheritance. We highlight essential definitions of intergenerational and transgenerational transmission of disease risk with corresponding examples. We then explore how these phenomena may influence our understanding of psychiatric disorders leading toward new prevention and therapeutic approaches. PMID:26283147

Human-to-human transmission of Brucella - a systematic review.

PubMed

Tuon, Felipe F; Gondolfo, Regina B; Cerchiari, Natacha

2017-05-01

The most common form of transmitting human brucellosis is through contaminated food or direct contact with infected animals. Human-to-human transmission (HHT) has been described as isolated case reports. The aim of this systematic review was to describe all cases of HHT of human brucellosis reported in the medical literature. A literature search was conducted using PubMed, Scopus and Scielo databases using specific search terms published until March 2016. Two investigators independently determined study eligibility. All clinical data were evaluated to construct a table comprising the most important clinical aspects, age, gender, confirmed infection and detection method, transmission method and HHT confirmation and potential source of infection for human transmission. No statistical method was employed in this study. The initial search resulted in 615 publications, but only 35 were included. 45 brucellosis HHT cases were identified. 61% of patients who acquired brucellosis from another human were <1 year old (newborn and breastfeeding). Other cases include sexual transmission, blood transfusion, bone marrow transplantation and aerosol from an infected patient. Most patients (40/45) presented symptoms upon diagnosis. Diagnostic tests included culture, molecular methods and serum testing. Human brucellosis is a disease liable to transmission between humans by placental barrier, lactation, sexual and tissues such as blood and bone marrow. The indication for screening in tissue banks, transplants, blood and pregnancy is not yet established. © 2017 John Wiley & Sons Ltd.

Transmission Scheduling and Routing Algorithms for Delay Tolerant Networks

NASA Technical Reports Server (NTRS)

Dudukovich, Rachel; Raible, Daniel E.

2016-01-01

The challenges of data processing, transmission scheduling and routing within a space network present a multi-criteria optimization problem. Long delays, intermittent connectivity, asymmetric data rates and potentially high error rates make traditional networking approaches unsuitable. The delay tolerant networking architecture and protocols attempt to mitigate many of these issues, yet transmission scheduling is largely manually configured and routes are determined by a static contact routing graph. A high level of variability exists among the requirements and environmental characteristics of different missions, some of which may allow for the use of more opportunistic routing methods. In all cases, resource allocation and constraints must be balanced with the optimization of data throughput and quality of service. Much work has been done researching routing techniques for terrestrial-based challenged networks in an attempt to optimize contact opportunities and resource usage. This paper examines several popular methods to determine their potential applicability to space networks.

Multibody simulation of vehicles equipped with an automatic transmission

NASA Astrophysics Data System (ADS)

Olivier, B.; Kouroussis, G.

2016-09-01

Nowadays automotive vehicles remain as one of the most used modes of transportation. Furthermore automatic transmissions are increasingly used to provide a better driving comfort and a potential optimization of the engine performances (by placing the gear shifts at specific engine and vehicle speeds). This paper presents an effective modeling of the vehicle using the multibody methodology (numerically computed under EasyDyn, an open source and in-house library dedicated to multibody simulations). However, the transmission part of the vehicle is described by the usual equations of motion computed using a systematic matrix approach: del Castillo's methodology for planetary gear trains. By coupling the analytic equations of the transmission and the equations computed by the multibody methodology, the performances of any vehicle can be obtained if the characteristics of each element in the vehicle are known. The multibody methodology offers the possibilities to develop the vehicle modeling from 1D-motion to 3D-motion by taking into account the rotations and implementing tire models. The modeling presented in this paper remains very efficient and provides an easy and quick vehicle simulation tool which could be used in order to calibrate the automatic transmission.

Transmission Planning Analysis Tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

2015-06-23

Developed to solve specific problem: Assist transmission planning for regional transfers in interconnected power systems. This work was originated in a study for the U.S. Department of State, to recommend transmission reinforcements for the Central American regional system that interconnects 6 countries. Transmission planning analysis is currently performed by engineers with domainspecific and systemspecific knowledge without a unique methodology. The software codes of this disclosure assists engineers by defining systematic analysis procedures to help identify weak points and make decisions on transmission planning of regional interconnected power systems. Transmission Planning Analysis Tool groups PSS/E results of multiple AC contingency analysismore » and voltage stability analysis and QV analysis of many scenarios of study and arrange them in a systematic way to aid power system planning engineers or transmission operators in effective decision]making process or in the off]line study environment.« less

Linden flower (Tilia spp.) as potential vehicle of Clostridium botulinum spores in the transmission of infant botulism.

PubMed

Bianco, M I; Lúquez, C; De Jong, L I T; Fernández, R A

2009-01-01

Infant botulism is an intestinal toxemia caused principally by Clostridium botulinum. Since the infection occurs in the intestinal tract, numerous food products have been investigated for the presence of C. botulinum and its neurotoxins. In many countries, people use linden flower (Tilia spp) tea as a household remedy and give it to infants as a sedative. Therefore, to help provide a clear picture of this disease transmission, we investigated the presence of botulinum spores in linden flowers. In this study, we analyzed 100 samples of unwrapped linden flowers and 100 samples of linden flowers in tea bags to determine the prevalence and spore-load of C. botulinum. Results were analyzed by the Fisher test. We detected a prevalence of 3% of botulinum spores in the unwrapped linden flowers analyzed and a spore load of 30 spores per 100 grams. None of the industrialized linden flowers analyzed were contaminated with botulinum spores. C. botulinum type A was identified in two samples and type B in one sample. Linden flowers must be considered a potential vehicle of C. botulinum, and the ingestion of linden flower tea can represent a risk factor for infant botulism.

The effect of magnetic field on chiral transmission in p-n-p graphene junctions.

PubMed

Li, Yuan; Wan, Qi; Peng, Yingzi; Wang, Guanqing; Qian, Zhenghong; Zhou, Guanghui; Jalil, Mansoor B A

2015-12-18

We investigate Klein tunneling in graphene heterojunctions under the influence of a perpendicular magnetic field via the non-equilibrium Green's function method. We find that the angular dependence of electron transmission is deflected sideways, resulting in the suppression of normally incident electrons and overall decrease in conductance. The off-normal symmetry axis of the transmission profile was analytically derived. Overall tunneling conductance decreases to almost zero regardless of the potential barrier height V0 when the magnetic field (B-field) exceeds a critical value, thus achieving effective confinement of Dirac fermions. The critical field occurs when the width of the magnetic field region matches the diameter of the cyclotron orbit. The potential barrier also induces distinct Fabry-Pérot fringe patterns, with a "constriction region" of low transmission when V0 is close to the Fermi energy. Application of B-field deflects the Fabry-Pérot interference pattern to an off-normal angle. Thus, the conductance of the graphene heterojunctions can be sharply modulated by adjusting the B-field strength and the potential barrier height relative to the Fermi energy.

The effect of magnetic field on chiral transmission in p-n-p graphene junctions

NASA Astrophysics Data System (ADS)

Li, Yuan; Wan, Qi; Peng, Yingzi; Wang, Guanqing; Qian, Zhenghong; Zhou, Guanghui; Jalil, Mansoor B. A.

2015-12-01

We investigate Klein tunneling in graphene heterojunctions under the influence of a perpendicular magnetic field via the non-equilibrium Green’s function method. We find that the angular dependence of electron transmission is deflected sideways, resulting in the suppression of normally incident electrons and overall decrease in conductance. The off-normal symmetry axis of the transmission profile was analytically derived. Overall tunneling conductance decreases to almost zero regardless of the potential barrier height when the magnetic field (B-field) exceeds a critical value, thus achieving effective confinement of Dirac fermions. The critical field occurs when the width of the magnetic field region matches the diameter of the cyclotron orbit. The potential barrier also induces distinct Fabry-Pérot fringe patterns, with a “constriction region” of low transmission when is close to the Fermi energy. Application of B-field deflects the Fabry-Pérot interference pattern to an off-normal angle. Thus, the conductance of the graphene heterojunctions can be sharply modulated by adjusting the B-field strength and the potential barrier height relative to the Fermi energy.

Transmission of Hepatitis E Virus in Developing Countries

PubMed Central

Khuroo, Mohammad S.; Khuroo, Mehnaaz S.; Khuroo, Naira S.

2016-01-01

Hepatitis E virus (HEV), an RNA virus of the Hepeviridae family, has marked heterogeneity. While all five HEV genotypes can cause human infections, genotypes HEV-1 and -2 infect humans alone, genotypes HEV-3 and -4 primarily infect pigs, boars and deer, and genotype HEV-7 primarily infects dromedaries. The global distribution of HEV has distinct epidemiological patterns based on ecology and socioeconomic factors. In resource-poor countries, disease presents as large-scale waterborne epidemics, and few epidemics have spread through person-to-person contact; however, endemic diseases within these countries can potentially spread through person-to-person contact or fecally contaminated water and foods. Vertical transmission of HEV from infected mother to fetus causes high fetal and perinatal mortality. Other means of transmission, such as zoonotic transmission, can fluctuate depending upon the region and strain of the virus. For instance, zoonotic transmission can sometimes play an insignificant role in human infections, such as in India, where human and pig HEV infections are unrelated. However, recently China and Southeast Asia have experienced a zoonotic spread of HEV-4 from pigs to humans and this has become the dominant mode of transmission of hepatitis E in eastern China. Zoonotic HEV infections in humans occur by eating undercooked pig flesh, raw liver, and sausages; through vocational contact; or via pig slurry, which leads to environmental contamination of agricultural products and seafood. Lastly, blood transfusion-associated HEV infections occur in many countries and screening of donors for HEV RNA is currently under serious consideration. To summarize, HEV genotypes 1 and 2 cause epidemic and endemic diseases in resource poor countries, primarily spreading through contaminated drinking water. HEV genotypes 3 and 4 on the other hand, cause autochthonous infections in developed, and many developing countries, by means of a unique zoonotic food

A Degree Distribution Optimization Algorithm for Image Transmission

NASA Astrophysics Data System (ADS)

Jiang, Wei; Yang, Junjie

2016-09-01

Luby Transform (LT) code is the first practical implementation of digital fountain code. The coding behavior of LT code is mainly decided by the degree distribution which determines the relationship between source data and codewords. Two degree distributions are suggested by Luby. They work well in typical situations but not optimally in case of finite encoding symbols. In this work, the degree distribution optimization algorithm is proposed to explore the potential of LT code. Firstly selection scheme of sparse degrees for LT codes is introduced. Then probability distribution is optimized according to the selected degrees. In image transmission, bit stream is sensitive to the channel noise and even a single bit error may cause the loss of synchronization between the encoder and the decoder. Therefore the proposed algorithm is designed for image transmission situation. Moreover, optimal class partition is studied for image transmission with unequal error protection. The experimental results are quite promising. Compared with LT code with robust soliton distribution, the proposed algorithm improves the final quality of recovered images obviously with the same overhead.

Transcriptome of the adult female malaria mosquito vector Anopheles albimanus.

PubMed

Martínez-Barnetche, Jesús; Gómez-Barreto, Rosa E; Ovilla-Muñoz, Marbella; Téllez-Sosa, Juan; García López, David E; Dinglasan, Rhoel R; Ubaida Mohien, Ceereena; MacCallum, Robert M; Redmond, Seth N; Gibbons, John G; Rokas, Antonis; Machado, Carlos A; Cazares-Raga, Febe E; González-Cerón, Lilia; Hernández-Martínez, Salvador; Rodríguez López, Mario H

2012-05-30

Human Malaria is transmitted by mosquitoes of the genus Anopheles. Transmission is a complex phenomenon involving biological and environmental factors of humans, parasites and mosquitoes. Among more than 500 anopheline species, only a few species from different branches of the mosquito evolutionary tree transmit malaria, suggesting that their vectorial capacity has evolved independently. Anopheles albimanus (subgenus Nyssorhynchus) is an important malaria vector in the Americas. The divergence time between Anopheles gambiae, the main malaria vector in Africa, and the Neotropical vectors has been estimated to be 100 My. To better understand the biological basis of malaria transmission and to develop novel and effective means of vector control, there is a need to explore the mosquito biology beyond the An. gambiae complex. We sequenced the transcriptome of the An. albimanus adult female. By combining Sanger, 454 and Illumina sequences from cDNA libraries derived from the midgut, cuticular fat body, dorsal vessel, salivary gland and whole body, we generated a single, high-quality assembly containing 16,669 transcripts, 92% of which mapped to the An. darlingi genome and covered 90% of the core eukaryotic genome. Bidirectional comparisons between the An. gambiae, An. darlingi and An. albimanus predicted proteomes allowed the identification of 3,772 putative orthologs. More than half of the transcripts had a match to proteins in other insect vectors and had an InterPro annotation. We identified several protein families that may be relevant to the study of Plasmodium-mosquito interaction. An open source transcript annotation browser called GDAV (Genome-Delinked Annotation Viewer) was developed to facilitate public access to the data generated by this and future transcriptome projects. We have explored the adult female transcriptome of one important New World malaria vector, An. albimanus. We identified protein-coding transcripts involved in biological processes that may

Blocking Plasmodium falciparum Malaria Transmission with Drugs: The Gametocytocidal and Sporontocidal Properties of Current and Prospective Antimalarials

PubMed Central

Kiszewski, Anthony E.

2011-01-01

Drugs that kill or inhibit the sexual stages of Plasmodium could potentially amplify or synergize the impact of other interventions by blocking transmission to mosquitoes. Primaquine and other 8-aminoquinolines have long offered such potential, but safety and other concerns have limited their use. Although transmission-blocking properties are not often a priority of drug discovery efforts, a number of interesting gametocytocidal and/or sporontocidal drug candidates have emerged in recent years. Some still bear significant technical and safety concerns, while others have passed clinical trials and are on the verge of entering the antimalarial armamentarium. Recent advances in our knowledge of gametocyte differentiation, gametogenesis and sporogony have also led to the identification of a large array of potential new targets for drugs that might interfere with malaria transmission. This review examines the properties of existing and prospective drugs, mechanisms of action, counter-indications and their potential role in regional malaria elimination efforts.

Transmission of Human Respiratory Syncytial Virus in the Immunocompromised Ferret Model

PubMed Central

de Waal, Leon; Smits, Saskia L.; Veldhuis Kroeze, Edwin J. B.; van Amerongen, Geert; Pohl, Marie O.; Osterhaus, Albert D. M. E.; Stittelaar, Koert J.

2018-01-01

Human respiratory syncytial virus (HRSV) causes substantial morbidity and mortality in vulnerable patients, such as the very young, the elderly, and immunocompromised individuals of any age. Nosocomial transmission of HRSV remains a serious challenge in hospital settings, with intervention strategies largely limited to infection control measures, including isolation of cases, high standards of hand hygiene, cohort nursing, and use of personal protective equipment. No vaccines against HRSV are currently available, and treatment options are largely supportive care and expensive monoclonal antibody or antiviral therapy. The limitations of current animal models for HRSV infection impede the development of new preventive and therapeutic agents, and the assessment of their potential for limiting HRSV transmission, in particular in nosocomial settings. Here, we demonstrate the efficient transmission of HRSV from immunocompromised ferrets to both immunocompromised and immunocompetent contact ferrets, with pathological findings reproducing HRSV pathology in humans. The immunocompromised ferret-HRSV model represents a novel tool for the evaluation of intervention strategies against nosocomial transmission of HRSV. PMID:29301313

Underwater unidirectional acoustic transmission through a plate with bilateral asymmetric gratings

NASA Astrophysics Data System (ADS)

Song, Ailing; Chen, Tianning; Wang, Xiaopeng; Xi, Yanhui; Liang, Qingxuan

2018-04-01

In this paper, a novel underwater unidirectional acoustic transmission (UAT) device consisting of a plate with bilateral asymmetric gratings is proposed and numerically investigated. The transmission spectra, the acoustic intensity field distributions, and the displacement field distributions are numerically calculated based on the finite element method. The transmission spectra show that the proposed device exhibits different UAT effects in three bands. The acoustic intensity field distributions demonstrate that the proposed device can realize UAT, which agree well with the transmission spectra. The mechanism is discussed by analyzing the displacement field distributions, and the UAT is attributed to the symmetric mode excited in brass plate. Furthermore, the effects of the lattice constant, the upper slit width, and the lower slit width on bands are discussed. Our design provides a good reference for designing underwater UAT devices and has potential applications in some fields, such as medical ultrasonic devices, acoustic barrier, and noise insulation.

Transmission Kikuchi diffraction and transmission electron forescatter imaging of electropolished and FIB manufactured TEM specimens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zieliński, W., E-mail: wiziel@inmat.pw.edu.pl; Płociński, T.; Kurzydłowski, K.J.

2015-06-15

We present a study of the efficiency of the utility of scanning electron microscope (SEM)-based transmission methods for characterizing grain structure in thinned bulk metals. Foils of type 316 stainless steel were prepared by two methods commonly used for transmission electron microscopy — double-jet electropolishing and focused ion beam milling. A customized holder allowed positioning of the foils in a configuration appropriate for both transmission electron forward scatter diffraction, and for transmission imaging by the use of a forescatter detector with two diodes. We found that both crystallographic orientation maps and dark-field transmitted images could be obtained for specimens preparedmore » by either method. However, for both methods, preparation-induced artifacts may affect the quality or accuracy of transmission SEM data, especially those acquired by the use of transmission Kikuchi diffraction. Generally, the quality of orientation data was better for specimens prepared by electropolishing, due to the absence of ion-induced damage. - Highlights: • The transmission imaging and diffraction techniques are emerging in scanning electron microscopy (SEM) as promising new field of materials characterization. • The manuscript titled: “Transmission Kikuchi Diffraction and Transmission Electron Forescatter Imaging of Electropolished and FIB Manufactured TEM Specimens” documents how different specimen thinning procedures can effect efficiency of transmission Kikuchi diffraction and transmission electron forescatter imaging. • The abilities to make precision crystallographic orientation maps and dark-field images in transmission was studied on electropolished versus focus ion beam manufactured TEM specimens. • Depending on the need, electropolished and focused ion beam technique may produce suitable specimens for transmission imaging and diffraction in SEM.« less

Mucosal Immunization with a Candidate Universal Influenza Vaccine Reduces Virus Transmission in a Mouse Model

PubMed Central

Lo, Chia-Yun; Misplon, Julia A.; Epstein, Suzanne L.

2014-01-01

ABSTRACT Pandemic influenza is a major public health concern, but conventional strain-matched vaccines are unavailable early in a pandemic. Candidate “universal” vaccines targeting the viral antigens nucleoprotein (NP) and matrix 2 (M2), which are conserved among all influenza A virus strains and subtypes, could be manufactured in advance for use at the onset of a pandemic. These vaccines do not prevent infection but can reduce disease severity, deaths, and virus titers in the respiratory tract. We hypothesized that such immunization may reduce virus transmission from vaccinated, infected animals. To investigate this hypothesis, we studied mouse models for direct-contact and airborne transmission of H1N1 and H3N2 influenza viruses. We established conditions under which virus transmission occurs and showed that transmission efficiency is determined in part at the level of host susceptibility to infection. Our findings indicate that virus transmission between mice has both airborne and direct-contact components. Finally, we demonstrated that immunization with recombinant adenovirus vectors expressing NP and M2 significantly reduced the transmission of virus to cohoused, unimmunized mice in comparison to controls. These findings have broad implications for the impact of conserved-antigen vaccines, not only in protecting the vaccinated individual but also in protecting others by limiting influenza virus transmission and potentially reducing the size of epidemics. IMPORTANCE Using a mouse model of influenza A virus transmission, we demonstrate that a candidate “universal” influenza vaccine both protects vaccinated animals from lethal infection and reduces the transmission of virus from vaccinated to nonvaccinated mice. This vaccine induces immunity against proteins conserved among all known influenza A virus strains and subtypes, so it could be used early in a pandemic before conventional strain-matched vaccines are available and could potentially reduce the

Tonsil Epithelial Factors May Influence Oropharyngeal Human Immunodeficiency Virus Transmission

PubMed Central

Moutsopoulos, Niki M.; Nares, Salvador; Nikitakis, Nikolaos; Rangel, Zoila; Wen, Jie; Munson, Peter; Sauk, John; Wahl, Sharon M.

2007-01-01

Tonsil epithelium has been implicated in human immunodeficiency virus (HIV) pathogenesis, but its role in oral transmission remains controversial. To study characteristics of this tissue, which may influence susceptibility or resistance to HIV, we performed microarray analysis of the tonsil epithelium. Our data revealed that genes related to immune functions such as antibody production and antigen processing were increasingly expressed in tonsil compared with the epithelium of another oropharyngeal site, the gingival epithelium. Importantly, tonsil epithelium highly expressed genes associated with HIV entrapment and/or transmission, including the HIV co-receptor CXCR4 and the potential HIV-binding molecules FcRγIII, complement receptor 2, and various complement components. Immunohistochemical staining confirmed the increased presence of CXCR4 in the tonsil epithelium compared with multiple oral epithelial sites, particularly in basal and parabasal layers. This increased expression of molecules involved in viral recognition, binding, and entry may favor virus-epithelium interactions in an environment with reduced innate antiviral mechanisms. Specifically, secretory leukocyte protease inhibitor, an innate molecule with anti-HIV activity, was minimal in the tonsil epithelium, in contrast to oral mucosa. Collectively, our data suggest that increased expression of molecules associated with HIV binding and entry coupled with decreased innate antiviral factors may render the tonsil a potential site for oral transmission. PMID:17620369

Potential environmental effects of 765-kV transmission lines: views before the New York State Public Service Commission, Cases 26529 and 26559, 1976-1978

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott-Walton, B.; Clark, K. M.; Holt, B. R.

1979-11-01

Testimony given before the New York Public Service Commission in two recent cases on the potential environmental effects of 765-kV overhead ac transmission lines is reviewed. The testimony focused on the potential effects of audible noise, on the potential biological effects of the electromagnetic fields, on the potential for electric shocks to people who touch vehicles parked under the proposed lines, on the potential effects of the electromagnetic fields on electronic cardiac pacemakers, and on potential effects of ozone produced by corona discharge from the lines. The testimony fully explored these questions; however, it did not resolve all of them.more » The testimony indicates potential impacts from the audible noise and from the electrostatic shocks that people can receive when they touch a large vehicle parked under the lines. The testimony also indicates that certain cardiac pacemaker and lead combinations may, under certain circumstances, undergo reversion to a fixed rate of pacing in the presence of the fields under the lines, but that little risk to cardiac patients results except possibly for those patients for whom competition between the heart's own rate and the pacemaker rate presents a health risk. The testimony fails to demonstrate biological hazards from the field; further research is necessary to understand better the effects of the fields on biological systems. The testimony indicates that ozone produced by the lines will not significantly affect the environment.« less

75 FR 62023 - Transmission Planning and Cost Allocation by Transmission Owning and Operating Public Utilities

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-07

...] Transmission Planning and Cost Allocation by Transmission Owning and Operating Public Utilities September 29... (75 FR 37884) proposing to amend the transmission planning and cost allocation requirements... transmission needs driven by public policy requirements established by state or federal laws or regulations...

Transmission of Ebola Viruses: What We Know and What We Do Not Know

PubMed Central

Moore, Kristine A.; Kelley, Nicholas S.; Brosseau, Lisa M.; Wong, Gary; Murphy, Frederick A.; Peters, Clarence J.; LeDuc, James W.; Russell, Phillip K.; Van Herp, Michel; Kapetshi, Jimmy; Muyembe, Jean-Jacques T.; Ilunga, Benoit Kebela; Strong, James E.; Grolla, Allen; Wolz, Anja; Kargbo, Brima; Kargbo, David K.; Formenty, Pierre; Sanders, David Avram; Kobinger, Gary P.

2015-01-01

ABSTRACT Available evidence demonstrates that direct patient contact and contact with infectious body fluids are the primary modes for Ebola virus transmission, but this is based on a limited number of studies. Key areas requiring further study include (i) the role of aerosol transmission (either via large droplets or small particles in the vicinity of source patients), (ii) the role of environmental contamination and fomite transmission, (iii) the degree to which minimally or mildly ill persons transmit infection, (iv) how long clinically relevant infectiousness persists, (v) the role that “superspreading events” may play in driving transmission dynamics, (vi) whether strain differences or repeated serial passage in outbreak settings can impact virus transmission, and (vii) what role sylvatic or domestic animals could play in outbreak propagation, particularly during major epidemics such as the 2013–2015 West Africa situation. In this review, we address what we know and what we do not know about Ebola virus transmission. We also hypothesize that Ebola viruses have the potential to be respiratory pathogens with primary respiratory spread. PMID:25698835

Multidimensional modulation for next-generation transmission systems

NASA Astrophysics Data System (ADS)

Millar, David S.; Koike-Akino, Toshiaki; Kojima, Keisuke; Parsons, Kieran

2017-01-01

Recent research in multidimensional modulation has shown great promise in long reach applications. In this work, we will investigate the origins of this gain, the different approaches to multidimensional constellation design, and different performance metrics for coded modulation. We will also discuss the reason that such coded modulation schemes seem to have limited application at shorter distances, and the potential for other coded modulation schemes in future transmission systems.

Environmental transmission of Mycobacterium ulcerans drives dynamics of Buruli ulcer in endemic regions of Cameroon

NASA Astrophysics Data System (ADS)

Garchitorena, Andrés; Ngonghala, Calistus N.; Texier, Gaëtan; Landier, Jordi; Eyangoh, Sara; Bonds, Matthew H.; Guégan, Jean-François; Roche, Benjamin

2015-12-01

Buruli Ulcer is a devastating skin disease caused by the pathogen Mycobacterium ulcerans. Emergence and distribution of Buruli ulcer cases is clearly linked to aquatic ecosystems, but the specific route of transmission of M. ulcerans to humans remains unclear. Relying on the most detailed field data in space and time on M. ulcerans and Buruli ulcer available today, we assess the relative contribution of two potential transmission routes -environmental and water bug transmission- to the dynamics of Buruli ulcer in two endemic regions of Cameroon. The temporal dynamics of Buruli ulcer incidence are explained by estimating rates of different routes of transmission in mathematical models. Independently, we also estimate statistical models of the different transmission pathways on the spatial distribution of Buruli ulcer. The results of these two independent approaches are corroborative and suggest that environmental transmission pathways explain the temporal and spatial patterns of Buruli ulcer in our endemic areas better than the water bug transmission.

Revisiting adoption of high transmission PSM: pros, cons and path forward

NASA Astrophysics Data System (ADS)

Ma, Z. Mark; McDonald, Steve; Progler, Chris

2009-12-01

High transmission attenuated phase shift masks (Hi-T PSM) have been successfully applied in volume manufacturing for certain memory devices. Moreover, numerous studies have shown the potential benefits of Hi-T PSM for specific lithography applications. In this paper, the potential for extending Hi-T PSM to logic devices, is revisited with an emphasis on understanding layout, transmission, and manufacturing of Hi-T PSM versus traditional 6% embedded attenuated phase shift mask (EAPSM). Simulations on various layouts show Hi-T PSM has advantage over EAPSM in low duty cycle line patterns and high duty cycle space patterns. The overall process window can be enhanced when Hi- T PSM is combined with optimized optical proximity correction (OPC), sub-resolution assist features (SRAF), and source illumination. Therefore, Hi-T PSM may be a viable and lower cost alternative to other complex resolution enhancement technology (RET) approaches. Aerial image measurement system (AIMS) results on test masks, based on an inverse lithography technology (ILT) generated layout, confirm the simulation results. New advancement in high transmission blanks also make low topography Hi-T PSM a reality, which can minimize scattering effects in high NA lithography.

Structure-property relationships in an Al matrix Ca nanofilamentary composite conductor with potential application in high-voltage power transmission

NASA Astrophysics Data System (ADS)

Tian, Liang

This study investigated the processing-structure-properties relationships in an Al/Ca composites using both experiments and modeling/simulation. A particular focus of the project was understanding how the strength and electrical conductivity of the composite are related to its microstructure in the hope that a conducting material with light weight, high strength, and high electrical conductivity can be developed to produce overhead high-voltage power transmission cables. The current power transmission cables (e.g., Aluminum Conductor Steel Reinforced (ACSR)) have acceptable performance for high-voltage AC transmission, but are less well suited for high-voltage DC transmission due to the poorly conducting core materials that support the cable weight. This Al/Ca composite was produced by powder metallurgy and severe plastic deformation by extrusion and swaging. The fine Ca metal powders have been produced by centrifugal atomization with rotating liquid oil quench bath, and a detailed study about the atomization process and powder characteristics has been conducted. The microstructure of Al/Ca composite was characterized by electron microscopy. Microstructure changes at elevated temperature were characterized by thermal analysis and indirect resistivity tests. The strength and electrical conductivity were measured by tensile tests and four-point probe resistivity tests. Predicting the strength and electrical conductivity of the composite was done by micro-mechanics-based analytical modeling. Microstructure evolution was studied by mesoscale-thermodynamics-based phase field modeling and a preliminary atomistic molecular dynamics simulation. The application prospects of this composite was studied by an economic analysis. This study suggests that the Al/Ca (20 vol. %) composite shows promise for use as overhead power transmission cables. Further studies are needed to measure the corrosion resistance, fatigue properties and energized field performance of this composite.

75 FR 37883 - Transmission Planning and Cost Allocation by Transmission Owning and Operating Public Utilities

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-30

... Planning and Cost Allocation by Transmission Owning and Operating Public Utilities; Proposed Rule #0;#0...] Transmission Planning and Cost Allocation by Transmission Owning and Operating Public Utilities Issued June 17... Transmission Services by Public Utilities; Recovery of Stranded Costs by Public Utilities and Transmitting...

Breast milk transmission of flaviviruses in the context of Zika virus: A systematic review.

PubMed

Mann, Taylor Z; Haddad, Lisa B; Williams, Tonya R; Hills, Susan L; Read, Jennifer S; Dee, Deborah L; Dziuban, Eric J; Pérez-Padilla, Janice; Jamieson, Denise J; Honein, Margaret A; Shapiro-Mendoza, Carrie K

2018-06-08

Since the Zika virus epidemic in the Americas began in 2015, Zika virus transmission has occurred throughout the Americas. However, limited information exists regarding possible risks of transmission of Zika virus and other flaviviruses through breast feeding and human milk. We conducted a systematic review of the evidence regarding flaviviruses detection in and transmission through milk, specifically regarding Zika virus, Japanese encephalitis virus, tick-borne encephalitis virus, Powassan virus, West Nile virus, dengue virus, and yellow fever virus. Medline, Embase, Global Health, CINAHL, Cochrane Library, Scopus, Popline, Virtual Health Library, and WorldCat were searched through June 2017. Two authors independently screened potential studies for inclusion and extracted data. Human and nonhuman (animal) studies describing: 1) confirmed or suspected cases of mother-to-child transmission through milk; or 2) the presence of flavivirus genomic material in milk. Seventeen studies were included, four animal models and thirteen observational studies. Dengue virus, West Nile virus, and Zika virus viral ribonucleic acid was detected in human milk, including infectious Zika virus and dengue virus viral particles. Human breast-feeding transmission was confirmed for only yellow fever virus. There was evidence of milk-related transmission of dengue virus, Powassan virus, and West Nile virus in animal studies. Because the health advantages of breast feeding are considered greater than the potential risk of transmission, the World Health Organization recommends that mothers with possible or confirmed Zika virus infection or exposure continue to breast feed. This review did not identify any data that might alter this recommendation. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Environmental variables associated with anopheline larvae distribution and abundance in Yanomami villages within unaltered areas of the Brazilian Amazon.

PubMed

Sánchez-Ribas, Jordi; Oliveira-Ferreira, Joseli; Gimnig, John E; Pereira-Ribeiro, Cleomar; Santos-Neves, Maycon Sebastião Alberto; Silva-do-Nascimento, Teresa Fernandes

2017-11-16

Many indigenous villages in the Amazon basin still suffer from a high malaria burden. Despite this health situation, there are few studies on the bionomics of anopheline larvae in such areas. This publication aims to identify the main larval habitats of the most abundant anopheline species and to assess their associations with some environmental factors. We conducted a 19-month longitudinal study from January 2013 to July 2014, sampling anopheline larvae in two indigenous Yanomami communities, comprised of four villages each. All natural larval habitats were surveyed every two months with a 350 ml manual dipper, following a standardized larval sampling methodology. In a third study area, we conducted two field expeditions in 2013 followed by four systematic collections during the long dry season of 2014-2015. We identified 177 larval habitats in the three study areas, from which 9122 larvae belonging to 13 species were collected. Although species abundance differed between villages, An. oswaldoi (s.l.) was overall the most abundant species. Anopheles darlingi, An. oswaldoi (s.l.), An. triannulatus (s.s.) and An. mattogrossensis were primarily found in larval habitats that were partially or mostly sun-exposed. In contrast, An. costai-like and An. guarao-like mosquitoes were found in more shaded aquatic habitats. Anopheles darlingi was significantly associated with proximity to human habitations and larval habitats associated with river flood pulses and clear water. This study of anopheline larvae in the Brazilian Yanomami area detected high heterogeneities at micro-scale levels regarding species occurrence and densities. Sun exposure was a major modulator of anopheline occurrence, particularly for An. darlingi. Lakes associated with the rivers, and particularly oxbow lakes, were the main larval habitats for An. darlingi and other secondary malaria vectors. The results of this study will serve as a basis to plan larval source management activities in remote

Exploring the potential of expatriate social networks to reduce HIV and STI transmission: a protocol for a qualitative study

PubMed Central

Crawford, Gemma; Bowser, Nicole Jasmine; Brown, Graham Ernest; Maycock, Bruce Richard

2013-01-01

Introduction HIV diagnoses acquired among Australian men working or travelling overseas including  Southeast Asia are increasing. This change within transmission dynamics means traditional approaches to prevention need to be considered in new contexts. The significance and role of social networks in mediating sexual risk behaviours may be influential. Greater understanding of expatriate and traveller behaviour is required to understand how local relationships are formed, how individuals enter and are socialised into networks, and how these networks may affect sexual intentions and behaviours. This paper describes the development of a qualitative protocol to investigate how social networks of Australian expatriates and long-term travellers might support interventions to reduce transmission of HIV and sexually transmitted infections. Methods and analysis To explore the interactions of male expatriates and long-term travellers within and between their environments, symbolic interactionism will be the theoretical framework used. Grounded theory methods provide the ability to explain social processes through the development of explanatory theory. The primary data source will be interviews conducted in several rounds in both Australia and Southeast Asia. Purposive and theoretical sampling will be used to access participants whose data can provide depth and individual meaning. Ethics and dissemination The role of expatriate and long-term traveller networks and their potential to impact health are uncertain. This study seeks to gain a deeper understanding of the Australian expatriate culture, behavioural contexts and experiences within social networks in  Southeast Asia. This research will provide tangible recommendations for policy and practice as the findings will be disseminated to health professionals and other stakeholders, academics and the community via local research and evaluation networks, conference presentations and online forums. The Curtin University Human

Exploring the potential of expatriate social networks to reduce HIV and STI transmission: a protocol for a qualitative study.

PubMed

Crawford, Gemma; Bowser, Nicole Jasmine; Brown, Graham Ernest; Maycock, Bruce Richard

2013-01-01

HIV diagnoses acquired among Australian men working or travelling overseas including  Southeast Asia are increasing. This change within transmission dynamics means traditional approaches to prevention need to be considered in new contexts. The significance and role of social networks in mediating sexual risk behaviours may be influential. Greater understanding of expatriate and traveller behaviour is required to understand how local relationships are formed, how individuals enter and are socialised into networks, and how these networks may affect sexual intentions and behaviours. This paper describes the development of a qualitative protocol to investigate how social networks of Australian expatriates and long-term travellers might support interventions to reduce transmission of HIV and sexually transmitted infections. To explore the interactions of male expatriates and long-term travellers within and between their environments, symbolic interactionism will be the theoretical framework used. Grounded theory methods provide the ability to explain social processes through the development of explanatory theory. The primary data source will be interviews conducted in several rounds in both Australia and Southeast Asia. Purposive and theoretical sampling will be used to access participants whose data can provide depth and individual meaning. The role of expatriate and long-term traveller networks and their potential to impact health are uncertain. This study seeks to gain a deeper understanding of the Australian expatriate culture, behavioural contexts and experiences within social networks in  Southeast Asia. This research will provide tangible recommendations for policy and practice as the findings will be disseminated to health professionals and other stakeholders, academics and the community via local research and evaluation networks, conference presentations and online forums. The Curtin University Human Research Ethics Committee has granted approval for this

Anisotropic transmissive coding metamaterials based on dispersion modulation of spoof surface plasmon polaritons

NASA Astrophysics Data System (ADS)

Pang, Yongqiang; Li, Yongfeng; Zhang, Jieqiu; Chen, Hongya; Xu, Zhuo; Qu, Shaobo

2018-06-01

Anisotropic transmissive coding metamaterials (CMMs) have been designed and demonstrated in this work. High-efficiency transmission with the amplitudes close to unity is achieved by ultrathin metallic tapered blade structures, on which incident waves can be highly coupled into spoof surface plasmon polaritons (SSPPs). The transmission phase can be therefore manipulated with much freedom by designing the dispersion of the SSPPs. These tapered blade structures are designed as the anisotropic unit cells of the CMMs. Two 1-bit anisotropic CMMs with different coding sequences were first designed and simulated, and then a 2-bit anisotropic CMM was designed and measured experimentally. The measured results agree well with the simulations. It is expected that this work provides an alternative method for designing the transmissive CMMs, and may find potential applications in the beam forming technique.

Mother to Offspring Transmission of Chronic Wasting Disease in Reeves’ Muntjac Deer

PubMed Central

Nalls, Amy V.; McNulty, Erin; Powers, Jenny; Seelig, Davis M.; Hoover, Clare; Haley, Nicholas J.; Hayes-Klug, Jeanette; Anderson, Kelly; Stewart, Paula; Goldmann, Wilfred; Hoover, Edward A.; Mathiason, Candace K.

2013-01-01

The horizontal transmission of prion diseases has been well characterized in bovine spongiform encephalopathy (BSE), chronic wasting disease (CWD) of deer and elk and scrapie of sheep, and has been regarded as the primary mode of transmission. Few studies have monitored the possibility of vertical transmission occurring within an infected mother during pregnancy. To study the potential for and pathway of vertical transmission of CWD in the native cervid species, we used a small cervid model–the polyestrous breeding, indoor maintainable, Reeves’ muntjac deer–and determined that the susceptibility and pathogenesis of CWD in these deer reproduce that in native mule and white-tailed deer. Moreover, we demonstrate here that CWD prions are transmitted from doe to fawn. Maternal CWD infection also appears to result in lower percentage of live birth offspring. In addition, evolving evidence from protein misfolding cyclic amplification (PMCA) assays on fetal tissues suggest that covert prion infection occurs in utero. Overall, our findings demonstrate that transmission of prions from mother to offspring can occur, and may be underestimated for all prion diseases. PMID:23977159

Geographic potential of disease caused by Ebola and Marburg viruses in Africa.

PubMed

Peterson, A Townsend; Samy, Abdallah M

2016-10-01

Filoviruses represent a significant public health threat worldwide. West Africa recently experienced the largest-scale and most complex filovirus outbreak yet known, which underlines the need for a predictive understanding of the geographic distribution and potential for transmission to humans of these viruses. Here, we used ecological niche modeling techniques to understand the relationship between known filovirus occurrences and environmental characteristics. Our study derived a picture of the potential transmission geography of Ebola virus species and Marburg, paired with views of the spatial uncertainty associated with model-to-model variation in our predictions. We found that filovirus species have diverged ecologically, but only three species are sufficiently well known that models could be developed with significant predictive power. We quantified uncertainty in predictions, assessed potential for outbreaks outside of known transmission areas, and highlighted the Ethiopian Highlands and scattered areas across East Africa as additional potentially unrecognized transmission areas. Copyright © 2016 Elsevier B.V. All rights reserved.

Ferrets as Models for Influenza Virus Transmission Studies and Pandemic Risk Assessments

PubMed Central

Barclay, Wendy; Barr, Ian; Fouchier, Ron A.M.; Matsuyama, Ryota; Nishiura, Hiroshi; Peiris, Malik; Russell, Charles J.; Subbarao, Kanta; Zhu, Huachen

2018-01-01

The ferret transmission model is extensively used to assess the pandemic potential of emerging influenza viruses, yet experimental conditions and reported results vary among laboratories. Such variation can be a critical consideration when contextualizing results from independent risk-assessment studies of novel and emerging influenza viruses. To streamline interpretation of data generated in different laboratories, we provide a consensus on experimental parameters that define risk-assessment experiments of influenza virus transmissibility, including disclosure of variables known or suspected to contribute to experimental variability in this model, and advocate adoption of more standardized practices. We also discuss current limitations of the ferret transmission model and highlight continued refinements and advances to this model ongoing in laboratories. Understanding, disclosing, and standardizing the critical parameters of ferret transmission studies will improve the comparability and reproducibility of pandemic influenza risk assessment and increase the statistical power and, perhaps, accuracy of this model. PMID:29774862

Evaluation of the Efficacy, Potential for Vector Transmission, and Duration of Immunity of MP-12, an Attenuated Rift Valley Fever Virus Vaccine Candidate, in Sheep

PubMed Central

Bennett, Kristine E.; Drolet, Barbara S.; Lindsay, Robbin; Mecham, James O.; Reeves, Will K.; Weingartl, Hana M.; Wilson, William C.

2015-01-01

Rift Valley fever virus (RVFV) causes serious disease in ruminants and humans in Africa. In North America, there are susceptible ruminant hosts and competent mosquito vectors, yet there are no fully licensed animal vaccines for this arthropod-borne virus, should it be introduced. Studies in sheep and cattle have found the attenuated strain of RVFV, MP-12, to be both safe and efficacious based on early testing, and a 2-year conditional license for use in U.S. livestock has been issued. The purpose of this study was to further determine the vaccine's potential to infect mosquitoes, the duration of humoral immunity to 24 months postvaccination, and the ability to prevent disease and viremia from a virulent challenge. Vaccination experiments conducted in sheep found no evidence of a potential for vector transmission to 4 North American mosquito species. Neutralizing antibodies were elicited, with titers of >1:40 still present at 24 months postvaccination. Vaccinates were protected from clinical signs and detectable viremia after challenge with virulent virus, while control sheep had fever and high-titered viremia extending for 5 days. Antibodies to three viral proteins (nucleocapsid N, the N-terminal half of glycoprotein GN, and the nonstructural protein from the short segment NSs) were also detected to 24 months using competitive enzyme-linked immunosorbent assays. This study demonstrates that the MP-12 vaccine given as a single dose in sheep generates protective immunity to a virulent challenge with antibody duration of at least 2 years, with no evidence of a risk for vector transmission. PMID:26041042

Application of satellite estimates of rainfall distribution to simulate the potential for malaria transmission in Africa

NASA Astrophysics Data System (ADS)

Yamana, T. K.; Eltahir, E. A.

2009-12-01

The Hydrology, Entomology and Malaria Transmission Simulator (HYDREMATS) is a mechanistic model developed to assess malaria risk in areas where the disease is water-limited. This model relies on precipitation inputs as its primary forcing. Until now, applications of the model have used ground-based precipitation observations. However, rain gauge networks in the areas most affected by malaria are often sparse. The increasing availability of satellite based rainfall estimates could greatly extend the range of the model. The minimum temporal resolution of precipitation data needed was determined to be one hour. The CPC Morphing technique (CMORPH ) distributed by NOAA fits this criteria, as it provides 30-minute estimates at 8km resolution. CMORPH data were compared to ground observations in four West African villages, and calibrated to reduce overestimation and false alarm biases. The calibrated CMORPH data were used to force HYDREMATS, resulting in outputs for mosquito populations, vectorial capacity and malaria transmission.

Retinogeniculate transmission in wakefulness.

PubMed

Weyand, Theodore G

2007-08-01

Despite popular belief that the primary function of the thalamus is to "gate" sensory inputs by state, few studies have attempted to directly characterize the efficacy of such gating in the awake, behaving animal. I measured the efficacy of retinogeniculate transmission in the awake cat by taking advantage of the fact that many neurons in the lateral geniculate nucleus (LGN) are dominated by a single retinal input, and that this input produces a distinct event known as the S-potential. Retinal input failed to produce an LGN action potential half of the time. However, success or failure was powerfully tied to the recency of the S-potential. Short intervals tend to be successful and long intervals unsuccessful. For four of 12 neurons, the probability that a given S-potential could cause a spike exceeded 90% if that S-potential was preceded by an S-potential within the previous 10 ms (100 Hz). Whereas this temporal influence on efficacy has been demonstrated extensively in anesthetized animals, wakefulness is different in several ways. Overall efficacy is better in wakefulness than in anesthesia, the durations of facilitating effects are briefer in wakefulness, efficacy of long intervals is superior in wakefulness, and the temporal dependence can be briefly disrupted by altering background illumination. The last two observations may be particularly significant. Increased success at long intervals in wakefulness provides additional evidence that the spike code of the anesthetized animal is not the spike code of the awake animal. Altering retinogeniculate efficacy by altering visual conditions undermines the influence inter-S-potential interval might have in determining efficacy in the real world. Finally, S-potential amplitude, duration, and even slope are dynamic and systematic within wakefulness; providing further support that the S-potential is the extracellular signature of the retinal EPSP.

Ecological patterns of seed microbiome diversity, transmission, and assembly.

PubMed

Shade, Ashley; Jacques, Marie-Agnès; Barret, Matthieu

2017-06-01

Seeds are involved in the transmission of microorganisms from one plant generation to another and consequently act as the initial inoculum for the plant microbiota. The purpose of this mini-review is to provide an overview of current knowledge on the diversity, structure and role of the seed microbiota. The relative importance of the mode of transmission (vertical vs horizontal) of the microbial entities composing the seed microbiota as well as the potential connections existing between seed and other plant habitats such as the anthosphere and the spermosphere is discussed. Finally the governing processes (niche vs neutral) involved in the assembly and the dynamics of the seed microbiota are examined. Copyright © 2017. Published by Elsevier Ltd.

Design of free-space optical transmission system in computer tomography equipment

NASA Astrophysics Data System (ADS)

Liu, Min; Fu, Weiwei; Zhang, Tao

2018-04-01

Traditional computer tomography (CT) based on capacitive coupling cannot satisfy the high data rate transmission requirement. We design and experimentally demonstrate a free-space optical transmission system for CT equipment at a data rate of 10 Gb / s. Two interchangeable sections of 12 pieces of fiber with equal length is fabricated and tested by our designed laser phase distance measurement system. By locating the 12 collimators in the edge of the circle wheel evenly, the optical propagation characteristics for the 12 wired and wireless paths are similar, which can satisfy the requirement of high-speed CT transmission system. After bit error rate (BER) measurement in several conditions, the BER performances are below the value of 10 - 11, which has the potential in the future application scenario of CT equipment.

Choice of scale for integrating land use in malaria risk monitoring

NASA Astrophysics Data System (ADS)

Spangler, K. R.; Zaitchik, B. F.; Pan, W.; Vittor, A.; Patz, J.

2011-12-01

There were nearly 37,000 reported cases of malaria in Peru in 2009 alone. With over 30% of the population identified as being at "high risk" for exposure, detailed risk mapping, along with early detection and warning systems, are in critical need. While there is evidence that the increased formation of puddles arising from deforestation increases the breeding of the rainforest's primary malaria vector, Anopheles darlingi, neither the spatial structure of land uses/land cover changes (LUCC) nor the area of influence of LUCC on mosquito density has been systematically addressed. The radius of influence that LUCC - particularly areas of deforested land and other regions likely to see increases in stagnant water formation - has on mosquito presence is of particular importance, both for the design of warning systems and to inform future malaria transmission studies. Here, we present the results of satellite-based analysis of land use patterns and mosquito density along the Iquitos-Nauta road in the Peruvian Amazon. Comparing supervised classifications of Landsat images of the Iquitos region from 1996 and 2001 , land cover features around each of 832 mosquito sites were tabulated by percent at six different radii: 250m, 500m, 1000m, 2000m, 3000m, and 5000m. These results were then used as inputs in a mosquito prediction model that determined the most pertinent spatial scale necessary to predict both adult and larvae Anopheles mosquitoes (darlingi, benerocchi, oswaldoi, mattogrossenis, and rangeli). The application of this study is to provide a systematic means of determining which areas are at the highest risk of malaria infection in order to inform design of warning systems and future studies of land use and malaria in the Amazonian frontier.

Effects of temperature on Renibacterium salmoninarum infection and transmission potential in Chinook salmon, Oncorhynchus tshawytscha (Walbaum)

USGS Publications Warehouse

Purcell, Maureen K.; McKibben, Constance L.; Pearman-Gillman, Schuyler; Elliott, Diane G.; Winton, James R.

2016-01-01

Renibacterium salmoninarum is a significant pathogen of salmonids and the causative agent of bacterial kidney disease (BKD). Water temperature affects the replication rate of pathogens and the function of the fish immune system to influence the progression of disease. In addition, rapid shifts in temperature may serve as stressors that reduce host resistance. This study evaluated the effect of shifts in water temperature on established R. salmoninarum infections. We challenged Chinook salmon with R. salmoninarum at 12°C for 2 weeks and then divided the fish into three temperature groups (8, 12 and 15°C). Fish in the 8°C group had significantly higher R. salmoninarum-specific mortality, kidney R. salmoninarum loads and bacterial shedding rates relative to the fish held at 12 or 15°C. There was a trend towards suppressed bacterial load and shedding in the 15°C group, but the results were not significant. Bacterial load was a significant predictor of shedding for the 8 and 12°C groups but not for the 15°C group. Overall, our results showed little effect of temperature stress on the progress of infection, but do support the conclusion that cooler water temperatures contribute to infection progression and increased transmission potential in Chinook salmon infected with R. salmoninarum.

Morphological and Molecular Characterization of Lymnaeid Snails and Their Potential Role in Transmission of Fasciola spp. in Vietnam

PubMed Central

Doanh, Pham Ngoc; The, Dang Tat; Loan, Ho Thi; Losson, Bertrand; Caron, Yannick

2013-01-01

Freshwater snails of the family Lymnaeidae play an important role in the transmission of fascioliasis worldwide. In Vietnam, 2 common lymnaeid species, Lymnaea swinhoei and Lymnaea viridis, can be recognized on the basis of morphology, and a third species, Lymnaea sp., is known to exist. Recent studies have raised controversy about their role in transmission of Fasciola spp. because of confusion in identification of the snail hosts. The aim of this study is, therefore, to clarify the identities of lymnaeid snails in Vietnam by a combination of morphological and molecular approaches. The molecular analyses using the second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA clearly showed that lymnaeids in Vietnam include 3 species, Austropeplea viridis (morphologically identified as L. viridis), Radix auricularia (morphologically identified as L. swinhoei) and Radix rubiginosa (morphologically identified as Lymnaea sp.). R. rubiginosa is a new record for Vietnam. Among them, only A. viridis was found to be infected with Fasciola spp. These results provide a new insight into lymnaeid snails in Vietnam. Identification of lymnaeid snails in Vietnam and their role in the liver fluke transmission should be further investigated. PMID:24516270

Morphological and molecular characterization of lymnaeid snails and their potential role in transmission of Fasciola spp. in Vietnam.

PubMed

Dung, Bui Thi; Doanh, Pham Ngoc; The, Dang Tat; Loan, Ho Thi; Losson, Bertrand; Caron, Yannick

2013-12-01

Freshwater snails of the family Lymnaeidae play an important role in the transmission of fascioliasis worldwide. In Vietnam, 2 common lymnaeid species, Lymnaea swinhoei and Lymnaea viridis, can be recognized on the basis of morphology, and a third species, Lymnaea sp., is known to exist. Recent studies have raised controversy about their role in transmission of Fasciola spp. because of confusion in identification of the snail hosts. The aim of this study is, therefore, to clarify the identities of lymnaeid snails in Vietnam by a combination of morphological and molecular approaches. The molecular analyses using the second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA clearly showed that lymnaeids in Vietnam include 3 species, Austropeplea viridis (morphologically identified as L. viridis), Radix auricularia (morphologically identified as L. swinhoei) and Radix rubiginosa (morphologically identified as Lymnaea sp.). R. rubiginosa is a new record for Vietnam. Among them, only A. viridis was found to be infected with Fasciola spp. These results provide a new insight into lymnaeid snails in Vietnam. Identification of lymnaeid snails in Vietnam and their role in the liver fluke transmission should be further investigated.

Potential cost-effectiveness of maternal and infant antiretroviral interventions to prevent mother-to-child transmission during breast-feeding.

PubMed

Maclean, Courtney C; Stringer, Jeffrey S A

2005-04-15

One-third of maternal-to-child HIV transmission occurs during breast-feeding (BF). Several trials are currently evaluating the efficacy of postpartum antiretrovirals to reduce BF transmission. This study used Markov modeling to define the circumstances under which the following interventions would be cost-effective: BF for 6 months with daily infant nevirapine (NVP) prophylaxis; maternal combination antiretroviral therapy (ART) during pregnancy and for 6 months of BF; and maternal combination ART only for women who meet CD4 criteria. Each was compared to: BF for 12 months; BF for 6 months; and formula feeding for 12 months. Strategies were evaluated for a hypothetical cohort of 40,000 pregnant women in sub-Saharan Africa, in the context of available voluntary counseling and testing in antenatal care. Model estimates were derived from the literature and local sources. Sensitivity analyses were performed on uncertain estimates. The perspective used was that of a government health district. Using base case estimates, BF for 6 months was the economically preferred strategy: it cost 806,995 dollars and generated 446,208 quality-adjusted life-years (QALYs). Providing daily infant NVP cost an additional 93,638 dollars and generated 1183 additional QALYs, but its incremental cost-effectiveness ratio (ICER) of 79 dollars/QALY exceeded the standard willingness to pay (64 dollars/QALY) for most resource-poor settings. Maternal combination ART was potentially very effective but too costly for most resource-poor settings (ICER: 87 dollars/QALY). In order for daily infant NVP during BF to be preferred, it must have >/=44% relative efficacy or cost

Value transmissions between parents and children: gender and developmental phase as transmission belts.

PubMed

Roest, Annette M C; Dubas, Judith Semon; Gerris, Jan R M

2010-02-01

This study applied the gender role model of socialization theory, the developmental aging theory, and the topic salience perspective to the investigation of parent-child value transmissions. Specifically, we examined whether the bi-directionality and selectivity of value transmissions differed as a function of parents' and children's gender and children's developmental phase (adolescence versus emerging adulthood). Transmissions between parents and children from 402 Dutch families on the topics of work as duty and hedonism were studied across a 5-year period using structural equation modeling. As expected, we did not find convincing support for the general models of gender socialization and developmental aging. Instead, parent-child value transmissions appeared to be qualified by value salience. Particularly, high salience of work as duty for fathers was related with great paternal involvement in transmissions on this value orientation and high salience of hedonism for sons and adolescents was linked to transmissions from these groups to parents. Copyright (c) 2009 The Association for Professionals in Services for Adolescents. Published by Elsevier Ltd. Published by Elsevier Ltd. All rights reserved.

Transmission of human and macaque Plasmodium spp. to ex-captive orangutans in Kalimantan, Indonesia.

PubMed

Reid, Michael J C; Ursic, Raul; Cooper, Dawn; Nazzari, Hamed; Griffiths, Melinda; Galdikas, Birute M; Garriga, Rosa M; Skinner, Mark; Lowenberger, Carl

2006-12-01

Data are lacking on the specific diseases to which great apes are susceptible and the transmission dynamics and overall impact of these diseases. We examined the prevalence of Plasmodium spp. infections in semicaptive orangutans housed at the Orangutan Care Center and Quarantine, Central Kalimantan, Indonesia, by using a combination of microscopic and DNA molecular techniques to identify the Plasmodium spp. in each animal. Previous studies indicated 2 orangutan-specific Plasmodium spp., but our data show 4 Plasmodium spp. These findings provide evidence for P. vivax transmission between humans and orangutans and for P. cynomolgi transmission between macaques and orangutans. These data have potential implications for the conservation of orangutans and also for the bidirectional transmission of parasites between orangutans and humans visiting or living in the region.

Extracellular alpha-synuclein oligomers modulate synaptic transmission and impair LTP via NMDA-receptor activation.

PubMed

Diógenes, Maria José; Dias, Raquel B; Rombo, Diogo M; Vicente Miranda, Hugo; Maiolino, Francesca; Guerreiro, Patrícia; Näsström, Thomas; Franquelim, Henri G; Oliveira, Luís M A; Castanho, Miguel A R B; Lannfelt, Lars; Bergström, Joakim; Ingelsson, Martin; Quintas, Alexandre; Sebastião, Ana M; Lopes, Luísa V; Outeiro, Tiago Fleming

2012-08-22

Parkinson's disease (PD) is the most common representative of a group of disorders known as synucleinopathies, in which misfolding and aggregation of α-synuclein (a-syn) in various brain regions is the major pathological hallmark. Indeed, the motor symptoms in PD are caused by a heterogeneous degeneration of brain neurons not only in substantia nigra pars compacta but also in other extrastriatal areas of the brain. In addition to the well known motor dysfunction in PD patients, cognitive deficits and memory impairment are also an important part of the disorder, probably due to disruption of synaptic transmission and plasticity in extrastriatal areas, including the hippocampus. Here, we investigated the impact of a-syn aggregation on AMPA and NMDA receptor-mediated rat hippocampal (CA3-CA1) synaptic transmission and long-term potentiation (LTP), the neurophysiological basis for learning and memory. Our data show that prolonged exposure to a-syn oligomers, but not monomers or fibrils, increases basal synaptic transmission through NMDA receptor activation, triggering enhanced contribution of calcium-permeable AMPA receptors. Slices treated with a-syn oligomers were unable to respond with further potentiation to theta-burst stimulation, leading to impaired LTP. Prior delivery of a low-frequency train reinstated the ability to express LTP, implying that exposure to a-syn oligomers drives the increase of glutamatergic synaptic transmission, preventing further potentiation by physiological stimuli. Our novel findings provide mechanistic insight on how a-syn oligomers may trigger neuronal dysfunction and toxicity in PD and other synucleinopathies.

Early animal farming and zoonotic disease dynamics: modelling brucellosis transmission in Neolithic goat populations.

PubMed

Fournié, Guillaume; Pfeiffer, Dirk U; Bendrey, Robin

2017-02-01

Zoonotic pathogens are frequently hypothesized as emerging with the origins of farming, but evidence of this is elusive in the archaeological records. To explore the potential impact of animal domestication on zoonotic disease dynamics and human infection risk, we developed a model simulating the transmission of Brucella melitensis within early domestic goat populations. The model was informed by archaeological data describing goat populations in Neolithic settlements in the Fertile Crescent, and used to assess the potential of these populations to sustain the circulation of Brucella . Results show that the pathogen could have been sustained even at low levels of transmission within these domestic goat populations. This resulted from the creation of dense populations and major changes in demographic characteristics. The selective harvesting of young male goats, likely aimed at improving the efficiency of food production, modified the age and sex structure of these populations, increasing the transmission potential of the pathogen within these populations. Probable interactions between Neolithic settlements would have further promoted pathogen maintenance. By fostering conditions suitable for allowing domestic goats to become reservoirs of Brucella melitensis , the early stages of agricultural development were likely to promote the exposure of humans to this pathogen.

Early animal farming and zoonotic disease dynamics: modelling brucellosis transmission in Neolithic goat populations

PubMed Central

Pfeiffer, Dirk U.; Bendrey, Robin

2017-01-01

Zoonotic pathogens are frequently hypothesized as emerging with the origins of farming, but evidence of this is elusive in the archaeological records. To explore the potential impact of animal domestication on zoonotic disease dynamics and human infection risk, we developed a model simulating the transmission of Brucella melitensis within early domestic goat populations. The model was informed by archaeological data describing goat populations in Neolithic settlements in the Fertile Crescent, and used to assess the potential of these populations to sustain the circulation of Brucella. Results show that the pathogen could have been sustained even at low levels of transmission within these domestic goat populations. This resulted from the creation of dense populations and major changes in demographic characteristics. The selective harvesting of young male goats, likely aimed at improving the efficiency of food production, modified the age and sex structure of these populations, increasing the transmission potential of the pathogen within these populations. Probable interactions between Neolithic settlements would have further promoted pathogen maintenance. By fostering conditions suitable for allowing domestic goats to become reservoirs of Brucella melitensis, the early stages of agricultural development were likely to promote the exposure of humans to this pathogen. PMID:28386446

Transmission Line Jobs and Economic Development Impact (JEDI) Model User Reference Guide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldberg, M.; Keyser, D.

The Jobs and Economic Development Impact (JEDI) models, developed through the National Renewable Energy Laboratory (NREL), are freely available, user-friendly tools that estimate the potential economic impacts of constructing and operating power generation projects for a range of conventional and renewable energy technologies. The Transmission Line JEDI model can be used to field questions about the economic impacts of transmission lines in a given state, region, or local community. This Transmission Line JEDI User Reference Guide was developed to provide basic instruction on operating the model and understanding the results. This guide also provides information on the model's underlying methodology,more » as well as the parameters and references used to develop the cost data contained in the model.« less

Intergenerational Transmission of Self-Regulation: A Multidisciplinary Review and Integrative Conceptual Framework

PubMed Central

Bridgett, David J.; Burt, Nicole M.; Edwards, Erin S.; Deater-Deckard, Kirby

2014-01-01

This review examines mechanisms contributing to the intergenerational transmission of self-regulation. To provide an integrated account of how self-regulation is transmitted across generations, we draw from over 75 years of accumulated evidence, spanning case studies to experimental approaches, in literatures covering developmental, social, and clinical psychology, and criminology, physiology, genetics, and human and animal neuroscience (among others). First, we present a taxonomy of what self-regulation is and then examine how it develops – overviews that guide the main foci of the review. Next, studies supporting an association between parent and child self-regulation are reviewed. Subsequently, literature that considers potential social mechanisms of transmission, specifically parenting behavior, inter-parental (i.e., marital) relationship behaviors, and broader rearing influences (e.g., household chaos) are considered. Finally, literature providing evidence that prenatal programming may be the starting point of the intergenerational transmission of self-regulation is covered, along with key findings from the behavioral and molecular genetics literatures. To integrate these literatures, we introduce the Self-Regulation Intergenerational Transmission Model, a framework that brings together prenatal, social, and neurobiological mechanisms (spanning endocrine, neural, and genetic levels, including gene-environment interplay and epigenetic processes) to explain the intergenerational transmission of self-regulation. This model also incorporates potential transactional processes between generations (e.g., children’s self-regulation and parent-child interaction dynamics that may affect parents’ self-regulation) that further influence intergenerational processes. In pointing the way forward, we note key future directions and ways to address limitations in existing work throughout the review and in closing. We also conclude by noting several implications for

Microclimatic temperatures at Danish cattle farms, 2000-2016: quantifying the temporal and spatial variation in the transmission potential of Schmallenberg virus.

PubMed

Haider, Najmul; Cuellar, Ana Carolina; Kjær, Lene Jung; Sørensen, Jens Havskov; Bødker, Rene

2018-03-05

Microclimatic temperatures provide better estimates of vector-borne disease transmission parameters than standard meteorological temperatures, as the microclimate represent the actual temperatures to which the vectors are exposed. The objectives of this study were to quantify farm-level geographic variations and temporal patterns in the extrinsic incubation period (EIP) of Schmallenberg virus transmitted by Culicoides in Denmark through generation of microclimatic temperatures surrounding all Danish cattle farms. We calculated the hourly microclimatic temperatures at potential vector-resting sites within a 500 m radius of 22,004 Danish cattle farms for the months April to November from 2000 to 2016. We then modeled the daily EIP of Schmallenberg virus at each farm, assuming vectors choose resting sites either randomly or based on temperatures (warmest or coolest available) every hour. The results of the model output are presented as 17-year averages. The difference between the warmest and coolest microhabitats at the same farm was on average 3.7 °C (5th and 95th percentiles: 1.0 °C to 7.8 °C). The mean EIP of Schmallenberg virus (5th and 95th percentiles) for all cattle farms during spring, summer, and autumn was: 23 (18-33), 14 (12-18) and 51 (48-55) days, respectively, assuming Culicoides select resting sites randomly. These estimated EIP values were considerably shorter than those estimated using standard meteorological temperatures obtained from a numerical weather prediction model for the same periods: 43 (39-52), 21 (17-24) and 57 (55-58) days, respectively. When assuming that vectors actively select the coolest resting sites at a farm, the EIP was 2.3 (range: 1.1 to 4.1) times longer compared to that of the warmest sites at the same farm. We estimated a wide range of EIP in different microclimatic habitats surrounding Danish cattle farms, stressing the importance of identifying the specific resting sites of vectors when modeling vector-borne disease

Transmission of multidrug-resistant tuberculosis in the USA: a cross-sectional study.

PubMed

Moonan, Patrick K; Teeter, Larry D; Salcedo, Katya; Ghosh, Smita; Ahuja, Shama D; Flood, Jennifer; Graviss, Edward A

2013-09-01

Multidrug-resistant (MDR) tuberculosis is a potential threat to tuberculosis elimination, but the extent of MDR tuberculosis disease in the USA that is attributable to transmission within the country is unknown. We assessed transmission of MDR tuberculosis and potential contributing factors in the USA. In a cross-sectional study, clinical, demographic, epidemiological, and Mycobacterium tuberculosis genotype data were obtained during routine surveillance of all verified cases of MDR tuberculosis reported from eight states in the USA (California from Jan 1, 2007, to Dec 31, 2009; Texas from Jan 1, 2007, to March 31, 2009; and the states of Colorado, Maryland, Massachusetts, New York, Tennessee, and Washington from Jan 1, 2007 to Dec 31, 2008). In-depth interviews and health-record abstraction were done for all who consented to ascertain potential interpersonal connections. 168 cases of MDR tuberculosis were reported in the eight states during our study period. 92 individuals (55%) consented to in-depth interview. 20 (22%) of these individuals developed MDR tuberculosis as a result of transmission in the USA; a source case was identified for eight of them (9%). 20 individuals (22%) had imported active tuberculosis (ie, culture-confirmed disease within 3 months of entry into the USA). 38 (41%) were deemed to have reactivation of disease, of whom 14 (15%) had a known previous episode of tuberculosis outside the USA. Five individuals (5%) had documented treatment of a previous episode in the USA, and so were deemed to have relapsed. For nine cases (10%), insufficient evidence was available to definitively classify reason for presentation. About a fifth of cases of MDR tuberculosis in the USA can be linked to transmission within the country. Many individuals acquire MDR tuberculosis before entry into the USA. MDR tuberculosis needs to be diagnosed rapidly to reduce potential infectious periods, and clinicians should consider latent tuberculosis infection treatment

Sound transmission through a microperforated-panel structure with subdivided air cavities.

PubMed

Toyoda, Masahiro; Takahashi, Daiji

2008-12-01

The absorption characteristics of a microperforated-panel (MPP) absorber have been widely investigated, and MPPs are recognized as a next-generation absorbing material due to their fiber-free nature and attractive appearance. Herein, further possibilities of MPPs are investigated theoretically from a sound transmission viewpoint. Employing an analytical model composed of a typical MPP and a back wall with an infinite extent, transmission loss through the structure is obtained. Although MPP structures generally have great potential for sound absorption, an improvement in the transmission loss at midfrequencies, which is important for architectural sound insulation, is not sufficient when using a backing cavity alone. Hence, to improve transmission loss at midfrequencies, an air-cavity-subdivision technique is applied to MPP structures. By subdividing the air cavity with partitions, each cell can create a local one-dimensional sound field as well as lead to a normal incidence into the apertures, which is the most effective condition for Helmholtz-type resonance absorption. Moreover, by providing the same motion as the back wall to the MPP, the sound-insulation performance can be further improved at midfrequencies.

Cell transmission model of dynamic assignment for urban rail transit networks.

PubMed

Xu, Guangming; Zhao, Shuo; Shi, Feng; Zhang, Feilian

2017-01-01

For urban rail transit network, the space-time flow distribution can play an important role in evaluating and optimizing the space-time resource allocation. For obtaining the space-time flow distribution without the restriction of schedules, a dynamic assignment problem is proposed based on the concept of continuous transmission. To solve the dynamic assignment problem, the cell transmission model is built for urban rail transit networks. The priority principle, queuing process, capacity constraints and congestion effects are considered in the cell transmission mechanism. Then an efficient method is designed to solve the shortest path for an urban rail network, which decreases the computing cost for solving the cell transmission model. The instantaneous dynamic user optimal state can be reached with the method of successive average. Many evaluation indexes of passenger flow can be generated, to provide effective support for the optimization of train schedules and the capacity evaluation for urban rail transit network. Finally, the model and its potential application are demonstrated via two numerical experiments using a small-scale network and the Beijing Metro network.

Earth-ionosphere transmission line model for an impulsive geomagnetic disturbance at the dayside geomagnetic equator

NASA Astrophysics Data System (ADS)

Kikuchi, T.

2004-12-01

The near instantaneous onset of a geomagnetic impulse such as the preliminary reverse impulse (PRI) of the geomagnetic sudden commencement at high latitude and at the dayside geomagnetic equator has been explained by means of the TM0 mode waves in the Earth-ionosphere waveguide (Kikuchi and Araki, J. Atmosph. Terrest. Phys., 41, 927-936, 1979). There is, on the other hand, a time lag of the order of 10 sec in the peak amplitude of the magnetic impulse at the dayside equator. To explain these two temporal aspects, we examine transmission of the TM0 mode in a finite-length Earth-ionosphere transmission line composed of a finitely conducting ionosphere and the perfectly conducting Earth, with a fixed electric potential at one end and null potential at the other end of the transmission line, corresponding to the foot of a field-aligned current on the dawn- or dusk-side in the polar cap and middle point on the noon-midnight meridian at low latitude, respectively. Successive transmission and reflection in the bounded transmission line lead to that the ionospheric currents start to grow instantaneously, but reach a steady state with a relaxation time proportional to the length of the transmission line and the ionospheric conductivity. The relaxation time is of the order of 10 sec when we give high conductivity applicable to the equatorial ionosphere, which matches the observed time lag in the peak amplitude of the equatorial geomagnetic impulse. Consequently, the TM0 mode in the finite-length Earth-ionosphere transmission line explains both the instantaneous onset and time lag in the peak amplitude of the geomagnetic impulse at the dayside geomagnetic equator.

Progesterone Regulation of Synaptic Transmission and Plasticity in Rodent Hippocampus

ERIC Educational Resources Information Center

Foy, Michael R.; Akopian, Garnik; Thompson, Richard F.

2008-01-01

Ovarian hormones influence memory formation by eliciting changes in neural activity. The effects of various concentrations of progesterone (P4) on synaptic transmission and plasticity associated with long-term potentiation (LTP) and long-term depression (LTD) were studied using in vitro hippocampal slices. Extracellular studies show that the…

VLT FORS2 comparative transmission spectral survey of clear and cloudy exoplanet atmospheres

NASA Astrophysics Data System (ADS)

Nikolov, Nikolay; Sing, David; Gibson, Neale; Evans, Thomas; Barstow, Joanna Katy; Kataria, Tiffany; Wilson, Paul A.

2016-10-01

Transmission spectroscopy is a key to unlocking the secrets of close-in exoplanet atmospheres. Observations have started to unveil a vast diversity of irradiated giant planet atmospheres with clouds and hazes playing a definitive role across the entire mass and temperature regime. We have initiated a ground-based, multi-object transmission spectroscopy of a hand full of hot Jupiters, covering the wavelength range 360-850nm using the recently upgraded FOcal Reducer and Spectrograph (FORS2) mounted on the Very Large Telescope (VLT) at the European Southern Observatory (ESO). These targets were selected for comparative follow-up as their transmission spectra showed evidence for alkali metal absorption, based on the results of Hubble Space Telescope (HST) observations. This talk will discuss the first results from the programme, demonstrating excellent agreement between the transmission spectra measured from VLT and HST and further reinforce the findings of clear, cloudy and hazy atmospheres. More details will be discussed on the narrow alkali features obtained with FORS2 at higher resolution, revealing its high potential in securing optical transmission spectra. These FORS2 observations are the first ground-based detections of clear, cloudy and hazy hot-Jupiter atmosphere with a simultaneous detections of Na, K, and H2 Rayleigh scattering. Our program demonstrates the large potential of the instrument for optical transmission spectroscopy, capable of obtaining HST-quality light curves from the ground. Compared to HST, the larger aperture of VLT will allow for fainter targets to be observed and higher spectral resolution, which can greatly aid comparative exoplanet studies. This is important for further exploring the diversity of exoplanet atmospheres and is particularly complementary to the near- and mid-IR regime, to be covered by the upcoming James-Webb Space Telescope (JWST) and is readily applicable to less massive planets down to super-Earths.

Identifying multidrug resistant tuberculosis transmission hotspots using routinely collected data12

PubMed Central

Manjourides, Justin; Lin, Hsien-Ho; Shin, Sonya; Jeffery, Caroline; Contreras, Carmen; Cruz, Janeth Santa; Jave, Oswaldo; Yagui, Martin; Asencios, Luis; Pagano, Marcello; Cohen, Ted

2012-01-01

SUMMARY In most countries with large drug resistant tuberculosis epidemics, only those cases that are at highest risk of having MDRTB receive a drug sensitivity test (DST) at the time of diagnosis. Because of this prioritized testing, identification of MDRTB transmission hotspots in communities where TB cases do not receive DST is challenging, as any observed aggregation of MDRTB may reflect systematic differences in how testing is distributed in communities. We introduce a new disease mapping method, which estimates this missing information through probability–weighted locations, to identify geographic areas of increased risk of MDRTB transmission. We apply this method to routinely collected data from two districts in Lima, Peru over three consecutive years. This method identifies an area in the eastern part of Lima where previously untreated cases have increased risk of MDRTB. This may indicate an area of increased transmission of drug resistant disease, a finding that may otherwise have been missed by routine analysis of programmatic data. The risk of MDR among retreatment cases is also highest in these probable transmission hotspots, though a high level of MDR among retreatment cases is present throughout the study area. Identifying potential multidrug resistant tuberculosis (MDRTB) transmission hotspots may allow for targeted investigation and deployment of resources. PMID:22401962

Influence of climate on malaria transmission depends on daily temperature variation.

PubMed

Paaijmans, Krijn P; Blanford, Simon; Bell, Andrew S; Blanford, Justine I; Read, Andrew F; Thomas, Matthew B

2010-08-24

Malaria transmission is strongly influenced by environmental temperature, but the biological drivers remain poorly quantified. Most studies analyzing malaria-temperature relations, including those investigating malaria risk and the possible impacts of climate change, are based solely on mean temperatures and extrapolate from functions determined under unrealistic laboratory conditions. Here, we present empirical evidence to show that, in addition to mean temperatures, daily fluctuations in temperature affect parasite infection, the rate of parasite development, and the essential elements of mosquito biology that combine to determine malaria transmission intensity. In general, we find that, compared with rates at equivalent constant mean temperatures, temperature fluctuation around low mean temperatures acts to speed up rate processes, whereas fluctuation around high mean temperatures acts to slow processes down. At the extremes (conditions representative of the fringes of malaria transmission, where range expansions or contractions will occur), fluctuation makes transmission possible at lower mean temperatures than currently predicted and can potentially block transmission at higher mean temperatures. If we are to optimize control efforts and develop appropriate adaptation or mitigation strategies for future climates, we need to incorporate into predictive models the effects of daily temperature variation and how that variation is altered by climate change.