Single-Readout High-Density Memristor Crossbar

KAUST Repository

Zidan, M. A.; Omran, Hesham; Naous, Rawan; Salem, Ahmed Sultan; Fahmy, H. A. H.; Lu, W. D.; Salama, Khaled N.

2016-01-01

High-density memristor-crossbar architecture is a very promising technology for future computing systems. The simplicity of the gateless-crossbar structure is both its principal advantage and the source of undesired sneak-paths of current. This parasitic current could consume an enormous amount of energy and ruin the readout process. We introduce new adaptive-threshold readout techniques that utilize the locality and hierarchy properties of the computer-memory system to address the sneak-paths problem. The proposed methods require a single memory access per pixel for an array readout. Besides, the memristive crossbar consumes an order of magnitude less power than state-of-the-art readout techniques.

Food web topology and parasites in the pelagic zone of a subarctic lake

Science.gov (United States)

Amundsen, Per-Arne; Lafferty, K.D.; Knudsen, R.; Primicerio, R.; Klemetsen, A.; Kuris, A.M.

2009-01-01

Parasites permeate trophic webs with their often complex life cycles, but few studies have included parasitism in food web analyses. Here we provide a highly resolved food web from the pelagic zone of a subarctic lake and explore how the incorporation of parasites alters the topology of the web. 2. Parasites used hosts at all trophic levels and increased both food-chain lengths and the total number of trophic levels. Their inclusion in the network analyses more than doubled the number of links and resulted in an increase in important food-web characteristics such as linkage density and connectance. 3. More than half of the parasite taxa were trophically transmitted, exploiting hosts at multiple trophic levels and thus increasing the degree of omnivory in the trophic web. 4. For trophically transmitted parasites, the number of parasite-host links exhibited a positive correlation with the linkage density of the host species, whereas no such relationship was seen for nontrophically transmitted parasites. Our findings suggest that the linkage density of free-living species affects their exposure to trophically transmitted parasites, which may be more likely to adopt highly connected species as hosts during the evolution of complex life cycles. 5. The study supports a prominent role for parasites in ecological networks and demonstrates that their incorporation may substantially alter considerations of food-web structure and functioning. ?? 2009 British Ecological Society.

Parasites of fish larvae: do they follow metabolic energetic laws?

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Muñoz, Gabriela; Landaeta, Mauricio F; Palacios-Fuentes, Pamela; George-Nascimento, Mario

2015-11-01

Eumetazoan parasites in fish larvae normally exhibit large body sizes relative to their hosts. This observation raises a question about the potential effects that parasites might have on small fish. We indirectly evaluated this question using energetic metabolic laws based on body volume and the parasite densities. We compared the biovolume as well as the numeric and volumetric densities of parasites over the host body volume of larval and juvenile-adult fish and the average of these parasitological descriptors for castrator parasites and the parasites found in the fish studied here. We collected 5266 fish larvae using nearshore zooplankton sampling and 1556 juveniles and adult fish from intertidal rocky pools in central Chile. We considered only the parasitized hosts: 482 fish larvae and 629 juvenile-adult fish. We obtained 31 fish species; 14 species were in both plankton and intertidal zones. Fish larvae exhibited a significantly smaller biovolume but larger numeric and volumetric densities of parasites than juvenile-adult fish. Therefore, fish larvae showed a large proportion of parasite biovolume per unit of body host (cm(3)). However, the general scaling of parasitological descriptors and host body volume were similar between larvae and juvenile-adult fish. The ratio between the biovolume of parasites and the host body volume in fish larvae was similar to the proportion observed in castrator parasites. Furthermore, the ratios were different from those of juvenile-adult fish, which suggests that the presence of parasites implies a high energetic cost for fish larvae that would diminish the fitness of these small hosts.

In-circuit-measurement of parasitic elements in high gain high bandwidth low noise transimpedance amplifiers.

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Cochems, P; Kirk, A; Zimmermann, S

2014-12-01

Parasitic elements play an important role in the development of every high performance circuit. In the case of high gain, high bandwidth transimpedance amplifiers, the most important parasitic elements are parasitic capacitances at the input and in the feedback path, which significantly influence the stability, the frequency response, and the noise of the amplifier. As these parasitic capacitances range from a few picofarads down to only a few femtofarads, it is nearly impossible to measure them accurately using traditional LCR meters. Unfortunately, they also cannot be easily determined from the transfer function of the transimpedance amplifier, as it contains several overlapping effects and its measurement is only possible when the circuit is already stable. Therefore, we developed an in-circuit measurement method utilizing minimal modifications to the input stage in order to measure its parasitic capacitances directly and with unconditional stability. Furthermore, using the data acquired with this measurement technique, we both proposed a model for the complicated frequency response of high value thick film resistors as they are used in high gain transimpedance amplifiers and optimized our transimpedance amplifier design.

Mosquitoes meet microfluidics: High-throughput microfluidic tools for insect-parasite ecology in field conditions

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Prakash, Manu; Mukundarajan, Haripriya

2013-11-01

A simple bite from an insect is the transmission mechanism for many deadly diseases worldwide--including malaria, yellow fever, west nile and dengue. Very little is known about how populations of numerous insect species and disease-causing parasites interact in their natural habitats due to a lack of measurement techniques. At present, vector surveillance techniques involve manual capture by using humans as live bait, which is hard to justify on ethical grounds. Individual mosquitoes are manually dissected to isolate salivary glands to detect sporozites. With typical vector infection rates being very low even in endemic areas, it is almost impossible to get an accurate picture of disease distribution, in both space and time. Here we present novel high-throughput microfluidic tools for vector surveillance, specifically mosquitoes. A two-dimensional high density array with baits provide an integrated platform for multiplex PCR for detection of both vector and parasite species. Combining techniques from engineering and field ecology, methods and tools developed here will enable high-throughput measurement of infection rates for a number of diseases in mosquito populations in field conditions. Pew Foundation.

Maternal androgens in avian brood parasites and their hosts: responses to parasitism and competition?

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Hahn, Caldwell; Wingfield, John C.; Fox, David M.; Walker, Brian G.; Thomley, Jill E

2017-01-01

In the coevolutionary dynamic of avian brood parasites and their hosts, maternal (or transgenerational) effects have rarely been investigated. We examined the potential role of elevated yolk testosterone in eggs of the principal brood parasite in North America, the brown-headed cowbird, and three of its frequent host species. Elevated maternal androgens in eggs are a common maternal effect observed in many avian species when breeding conditions are unfavorable. These steroids accelerate embryo development, shorten incubation period, increase nestling growth rate, and enhance begging vigor, all traits that can increase the survival of offspring. We hypothesized that elevated maternal androgens in host eggs are a defense against brood parasitism. Our second hypothesis was that elevated maternal androgens in cowbird eggs are a defense against intra-specific competition. For host species, we found that elevated yolk testosterone was correlated with parasitized nests of small species, those whose nest success is most reduced by cowbird parasitism. For cowbirds, we found that elevated yolk testosterone was correlated with eggs in multiply-parasitized nests, which indicate intra-specific competition for nests due to high cowbird density. We propose experimental work to further examine the use of maternal effects by cowbirds and their hosts.

Parasite transmission in social interacting hosts: Monogenean epidemics in guppies

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Johnson, Mirelle B.; Lafferty, Kevin D.; van Oosterhout, Cock; Cable, Joanne

2011-01-01

Background Infection incidence increases with the average number of contacts between susceptible and infected individuals. Contact rates are normally assumed to increase linearly with host density. However, social species seek out each other at low density and saturate their contact rates at high densities. Although predicting epidemic behaviour requires knowing how contact rates scale with host density, few empirical studies have investigated the effect of host density. Also, most theory assumes each host has an equal probability of transmitting parasites, even though individual parasite load and infection duration can vary. To our knowledge, the relative importance of characteristics of the primary infected host vs. the susceptible population has never been tested experimentally. Methodology/Principal Findings Here, we examine epidemics using a common ectoparasite, Gyrodactylus turnbulli infecting its guppy host (Poecilia reticulata). Hosts were maintained at different densities (3, 6, 12 and 24 fish in 40 L aquaria), and we monitored gyrodactylids both at a population and individual host level. Although parasite population size increased with host density, the probability of an epidemic did not. Epidemics were more likely when the primary infected fish had a high mean intensity and duration of infection. Epidemics only occurred if the primary infected host experienced more than 23 worm days. Female guppies contracted infections sooner than males, probably because females have a higher propensity for shoaling. Conclusions/Significance These findings suggest that in social hosts like guppies, the frequency of social contact largely governs disease epidemics independent of host density.

Parasite infection alters nitrogen cycling at the ecosystem scale.

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Mischler, John; Johnson, Pieter T J; McKenzie, Valerie J; Townsend, Alan R

2016-05-01

Despite growing evidence that parasites often alter nutrient flows through their hosts and can comprise a substantial amount of biomass in many systems, whether endemic parasites influence ecosystem nutrient cycling, and which nutrient pathways may be important, remains conjectural. A framework to evaluate how endemic parasites alter nutrient cycling across varied ecosystems requires an understanding of the following: (i) parasite effects on host nutrient excretion; (ii) ecosystem nutrient limitation; (iii) effects of parasite abundance, host density, host functional role and host excretion rate on nutrient flows; and (iv) how this infection-induced nutrient flux compares to other pools and fluxes. Pathogens that significantly increase the availability of a limiting nutrient within an ecosystem should produce a measurable ecosystem-scale response. Here, we combined field-derived estimates of trematode parasite infections in aquatic snails with measurements of snail excretion and tissue stoichiometry to show that parasites are capable of altering nutrient excretion in their intermediate host snails (dominant grazers). We integrated laboratory measurements of host nitrogen excretion with field-based estimates of infection in an ecosystem model and compared these fluxes to other pools and fluxes of nitrogen as measured in the field. Eighteen nitrogen-limited ponds were examined to determine whether infection had a measurable effect on ecosystem-scale nitrogen cycling. Because of their low nitrogen content and high demand for host carbon, parasites accelerated the rate at which infected hosts excreted nitrogen to the water column in a dose-response manner, thereby shifting nutrient stoichiometry and availability at the ecosystem scale. Infection-enhanced fluxes of dissolved inorganic nitrogen were similar to other commonly important environmental sources of bioavailable nitrogen to the system. Additional field measurements within nitrogen-limited ponds indicated that

Intraspecific queen parasitism in a highly eusocial bee

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Wenseleers, Tom; Alves, Denise A.; Francoy, Tiago M.; Billen, Johan; Imperatriz-Fonseca, Vera L.

2011-01-01

Insect societies are well-known for their advanced cooperation, but their colonies are also vulnerable to reproductive parasitism. Here, we present a novel example of an intraspecific social parasitism in a highly eusocial bee, the stingless bee Melipona scutellaris. In particular, we provide genetic evidence which shows that, upon loss of the mother queen, many colonies are invaded by unrelated queens that fly in from unrelated hives nearby. The reasons for the occurrence of this surprising form of social parasitism may be linked to the fact that unlike honeybees, Melipona bees produce new queens in great excess of colony needs, and that this exerts much greater selection on queens to seek alternative reproductive options, such as by taking over other nests. Overall, our results are the first to demonstrate that queens in highly eusocial bees can found colonies not only via supersedure or swarming, but also by infiltrating and taking over other unrelated nests. PMID:20961883

Intraspecific queen parasitism in a highly eusocial bee.

Science.gov (United States)

Wenseleers, Tom; Alves, Denise A; Francoy, Tiago M; Billen, Johan; Imperatriz-Fonseca, Vera L

2011-04-23

Insect societies are well-known for their advanced cooperation, but their colonies are also vulnerable to reproductive parasitism. Here, we present a novel example of an intraspecific social parasitism in a highly eusocial bee, the stingless bee Melipona scutellaris. In particular, we provide genetic evidence which shows that, upon loss of the mother queen, many colonies are invaded by unrelated queens that fly in from unrelated hives nearby. The reasons for the occurrence of this surprising form of social parasitism may be linked to the fact that unlike honeybees, Melipona bees produce new queens in great excess of colony needs, and that this exerts much greater selection on queens to seek alternative reproductive options, such as by taking over other nests. Overall, our results are the first to demonstrate that queens in highly eusocial bees can found colonies not only via supersedure or swarming, but also by infiltrating and taking over other unrelated nests.

Plasmodium falciparum merozoite surface protein 1 - Glycosylation and localization to low-density, detergent-resistant membranes in the parasitized erythrocyte

DEFF Research Database (Denmark)

Hoessli, D.C.; Poincelet, M.; Gupta, Ramneek

2003-01-01

In addition to the major carbohydrate moieties of the glycosylphosphatidylinositol (GPI) anchor, we report that Plasmodium falciparum merozoite surface protein 1 (MSP-1) bears O-GlcNAc modifications predominantly in beta-anomeric configuration, in both the C- and N-terminal portions of the protein....... Subcellular fractionation of parasitized erythrocytes in the late trophozoite/schizont stage reveals that GPI-anchored C-terminal fragments of MSP-1 are recovered in Triton X-100 resistant, low-density membrane fractions. Our results suggest that O -GlcNAc-modified MSP-1 N-terminal fragments tend to localize...... within the parasitophorous vacuolar membrane while GPI-anchored MSP-1 C-terminal fragments associate with low-density, Triton X-100 resistant membrane domains (rafts), redistribute in the parasitized erythrocyte and are eventually shed as membrane vesicles that also contain the endogenous, GPI-linked CD...

Foodborne parasites from wildlife

DEFF Research Database (Denmark)

Kapel, Christian Moliin Outzen; Fredensborg, Brian Lund

2015-01-01

The majority of wild foods consumed by humans are sourced from intensively managed or semi-farmed populations. Management practices inevitably affect wildlife density and habitat characteristics, which are key elements in the transmission of parasites. We consider the risk of transmission...... of foodborne parasites to humans from wildlife maintained under natural or semi-natural conditions. A deeper understanding will be useful in counteracting foodborne parasites arising from the growing industry of novel and exotic foods....

A new method to improve multiplication factor in micro-pixel avalanche photodiodes with high pixel density

Energy Technology Data Exchange (ETDEWEB)

Sadygov, Z. [National Nuclear Research Center, Baku (Azerbaijan); Joint Institute for Nuclear Research, Dubna (Russian Federation); Ahmadov, F. [National Nuclear Research Center, Baku (Azerbaijan); Khorev, S. [Zecotek Photonics Inc., Vancouver (Canada); Sadigov, A., E-mail: saazik@yandex.ru [National Nuclear Research Center, Baku (Azerbaijan); Suleymanov, S. [National Nuclear Research Center, Baku (Azerbaijan); Madatov, R.; Mehdiyeva, R. [Institute of Radiation Problems, Baku (Azerbaijan); Zerrouk, F. [Zecotek Photonics Inc., Vancouver (Canada)

2016-07-11

Presented is a new model describing development of the avalanche process in time, taking into account the dynamics of electric field within the depleted region of the diode and the effect of parasitic capacitance shunting individual quenching micro-resistors on device parameters. Simulations show that the effective capacitance of a single pixel, which defines the multiplication factor, is the sum of the pixel capacitance and a parasitic capacitance shunting its quenching micro-resistor. Conclusions obtained as a result of modeling open possibilities of improving the pixel gain in micropixel avalanche photodiodes with high pixel density (or low pixel capacitance).

Effects of Snail Density on Growth, Reproduction and Survival of Biomphalaria alexandrina Exposed to Schistosoma mansoni

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T. D. Mangal

2010-01-01

Full Text Available The effects of snail density on Biomphalaria alexandrina parasitized with Schistosoma mansoni were investigated. Laboratory experiments were used to quantify the impact of high density on snail growth, fecundity, and survival. Density-dependent birth rates of snails were determined to inform mathematical models, which, until now, have assumed a linear relationship between density and fecundity. The experiments show that the rate of egg-laying followed a negative exponential distribution with increasing density and this was significantly affected by exposure to parasitic infection. High density also affected the weight of snails and survival to a greater degree than exposure to parasitic infection. Although snail growth rates were initially constrained by high density, they retained the potential for growth suggesting a reversible density-dependent mechanism. These experimental data can be used to parameterise models and confirm that snail populations are regulated by nonlinear density-dependent mechanisms.

Density-dependent sex ratio and sex-specific preference for host traits in parasitic bat flies.

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Szentiványi, Tamara; Vincze, Orsolya; Estók, Péter

2017-08-29

Deviation of sex ratios from unity in wild animal populations has recently been demonstrated to be far more prevalent than previously thought. Ectoparasites are prominent examples of this bias, given that their sex ratios vary from strongly female- to strongly male-biased both among hosts and at the metapopulation level. To date our knowledge is very limited on how and why these biased sex ratios develop. It was suggested that sex ratio and sex-specific aggregation of ectoparasites might be shaped by the ecology, behaviour and physiology of both hosts and their parasites. Here we investigate a highly specialised, hematophagous bat fly species with strong potential to move between hosts, arguably limited inbreeding effects, off-host developmental stages and extended parental care. We collected a total of 796 Nycteribia kolenatii bat flies from 147 individual bats using fumigation and subsequently determined their sex. We report a balanced sex ratio at the metapopulation level and a highly variable sex ratio among infrapopulations ranging from 100% male to 100% female. We show that infrapopulation sex ratio is not random and is highly correlated with infrapopulation size. Sex ratio is highly male biased in small and highly female biased in large infrapopulations. We show that this pattern is most probably the result of sex-specific preference in bat flies for host traits, most likely combined with a higher mobility of males. We demonstrate that female bat flies exert a strong preference for high host body condition and female hosts, while the distribution of males is more even. Our results suggest that locally biased sex ratios can develop due to sex-specific habitat preference of parasites. Moreover, it is apparent that the sex of both hosts and parasites need to be accounted for when a better understanding of host-parasite systems is targeted.

Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size

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Sara M. Rodríguez

2017-08-01

Full Text Available Background Parasites are essential components of natural communities, but the factors that generate skewed distributions of parasite occurrences and abundances across host populations are not well understood. Methods Here, we analyse at a seascape scale the spatiotemporal relationships of parasite exposure and host body-size with the proportion of infected hosts (i.e., prevalence and aggregation of parasite burden across ca. 150 km of the coast and over 22 months. We predicted that the effects of parasite exposure on prevalence and aggregation are dependent on host body-sizes. We used an indirect host-parasite interaction in which migratory seagulls, sandy-shore molecrabs, and an acanthocephalan worm constitute the definitive hosts, intermediate hosts, and endoparasite, respectively. In such complex systems, increments in the abundance of definitive hosts imply increments in intermediate hosts’ exposure to the parasite’s dispersive stages. Results Linear mixed-effects models showed a significant, albeit highly variable, positive relationship between seagull density and prevalence. This relationship was stronger for small (cephalothorax length >15 mm than large molecrabs (<15 mm. Independently of seagull density, large molecrabs carried significantly more parasites than small molecrabs. The analysis of the variance-to-mean ratio of per capita parasite burden showed no relationship between seagull density and mean parasite aggregation across host populations. However, the amount of unexplained variability in aggregation was strikingly higher in larger than smaller intermediate hosts. This unexplained variability was driven by a decrease in the mean-variance scaling in heavily infected large molecrabs. Conclusions These results show complex interdependencies between extrinsic and intrinsic population attributes on the structure of host-parasite interactions. We suggest that parasite accumulation—a characteristic of indirect host-parasite

Do the venous blood samples replicate malaria parasite densities found in capillary blood? A field study performed in naturally-infected asymptomatic children in Cameroon.

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Sandeu, Maurice M; Bayibéki, Albert N; Tchioffo, Majoline T; Abate, Luc; Gimonneau, Geoffrey; Awono-Ambéné, Parfait H; Nsango, Sandrine E; Diallo, Diadier; Berry, Antoine; Texier, Gaétan; Morlais, Isabelle

2017-08-17

The measure of new drug- or vaccine-based approaches for malaria control is based on direct membrane feeding assays (DMFAs) where gametocyte-infected blood samples are offered to mosquitoes through an artificial feeder system. Gametocyte donors are identified by the microscopic detection and quantification of malaria blood stages on blood films prepared using either capillary or venous blood. However, parasites are known to sequester in the microvasculature and this phenomenon may alter accurate detection of parasites in blood films. The blood source may then impact the success of mosquito feeding experiments and investigations are needed for the implementation of DMFAs under natural conditions. Thick blood smears were prepared from blood obtained from asymptomatic children attending primary schools in the vicinity of Mfou (Cameroon) over four transmission seasons. Parasite densities were determined microscopically from capillary and venous blood for 137 naturally-infected gametocyte carriers. The effect of the blood source on gametocyte and asexual stage densities was then assessed by fitting cumulative link mixed models (CLMM). DMFAs were performed to compare the infectiousness of gametocytes from the different blood sources to mosquitoes. Prevalence of Plasmodium falciparum asexual stages among asymptomatic children aged from 4 to 15 years was 51.8% (2116/4087). The overall prevalence of P. falciparum gametocyte carriage was 8.9% and varied from one school to another. No difference in the density of gametocyte and asexual stages was found between capillary and venous blood. Attempts to perform DMFAs with capillary blood failed. Plasmodium falciparum malaria parasite densities do not differ between capillary and venous blood in asymptomatic subjects for both gametocyte and trophozoite stages. This finding suggests that the blood source should not interfere with transmission efficiency in DMFAs.

A large proportion of asymptomatic Plasmodium infections with low and sub-microscopic parasite densities in the low transmission setting of Temotu Province, Solomon Islands: challenges for malaria diagnostics in an elimination setting

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Harris Ivor

2010-09-01

PCR positive P. falciparum, but failed to detect 12/13 microscopy and PCR positive P. vivax infections. Conclusion Asymptomatic malaria infections and infections with low and sub-microscopic parasite densities are highly prevalent in Temotu province where malaria transmission is low. This presents a challenge for elimination since the large proportion of the parasite reservoir will not be detected by standard active and passive case detection. Therefore effective mass screening and treatment campaigns will most likely need more sensitive assays such as a field deployable molecular based assay.

Environmentally transmitted parasites: Host-jumping in a heterogeneous environment.

Science.gov (United States)

Caraco, Thomas; Cizauskas, Carrie A; Wang, Ing-Nang

2016-05-21

Groups of chronically infected reservoir-hosts contaminate resource patches by shedding a parasite׳s free-living stage. Novel-host groups visit the same patches, where they are exposed to infection. We treat arrival at patches, levels of parasite deposition, and infection of the novel host as stochastic processes, and derive the expected time elapsing until a host-jump (initial infection of a novel host) occurs. At stationarity, mean parasite densities are independent of reservoir-host group size. But within-patch parasite-density variances increase with reservoir group size. The probability of infecting a novel host declines with parasite-density variance; consequently larger reservoir groups extend the mean waiting time for host-jumping. Larger novel-host groups increase the probability of a host-jump during any single patch visit, but also reduce the total number of visits per unit time. Interaction of these effects implies that the waiting time for the first infection increases with the novel-host group size. If the reservoir-host uses resource patches in any non-uniform manner, reduced spatial overlap between host species increases the waiting time for host-jumping. Copyright © 2016 Elsevier Ltd. All rights reserved.

Natural antibody responses to Plasmodium falciparum MSP3 and GLURP(R0) antigens are associated with low parasite densities in malaria patients living in the Central Region of Ghana

DEFF Research Database (Denmark)

Amoah, L. E.; Nuvor, S. V.; Obboh, E. K.

2017-01-01

Background: Plasmodium falciparum genetic diversity and multiplicity of infection (MOI) are parasite features that have been suggested to influence the acquisition of protective immunity against malaria. This study sought to assess the relationship between MOI and parasite density (PD) in malaria...... and adults diagnosed with uncomplicated P. falciparum malaria. Microscopy was used to estimate P. falciparum parasite density and polymerase chain reaction (PCR) amplification of the polymorphic regions of msp1 (PF3D7-0930300) and msp2 (PF3D7-0206800) was used for parasite genotyping and MOI determination....... The geometric mean (GM) for MOI determined by both msp1 and msp2 genotyping was 1.3 for the entire population and was generally higher in children than in adults. Seropositivity was estimated at 67 and 63% for GLURP(R0) and MSP3 antibodies, respectively, and antibody titers were negatively correlated...

Droplet Microfluidics Platform for Highly Sensitive and Quantitative Detection of Malaria-Causing Plasmodium Parasites Based on Enzyme Activity Measurement

DEFF Research Database (Denmark)

Juul, Sissel; Nielsen, Christine Juul Fælled; Labouriau, Rodrigo

2012-01-01

detectable at the single-molecule level. Combined with a droplet microfluidics lab-on-a-chip platform, this design allowed for sensitive, specific, and quantitative detection of all human-malaria-causing Plasmodium species in single drops of unprocessed blood with a detection limit of less than one parasite....../μL. Moreover, the setup allowed for detection of Plasmodium parasites in noninvasive saliva samples from infected patients. During recent years malaria transmission has declined worldwide, and with this the number of patients with low-parasite density has increased. Consequently, the need for accurate...

Host responses to interspecific brood parasitism: a by-product of adaptations to conspecific parasitism?

Science.gov (United States)

Samas, Peter; Hauber, Mark E; Cassey, Phillip; Grim, Tomas

2014-01-01

Why have birds evolved the ability to reject eggs? Typically, foreign egg discrimination is interpreted as evidence that interspecific brood parasitism (IP) has selected for the host's ability to recognize and eliminate foreign eggs. Fewer studies explore the alternative hypothesis that rejection of interspecific eggs is a by-product of host defenses, evolved against conspecific parasitism (CP). We performed a large scale study with replication across taxa (two congeneric Turdus thrushes), space (populations), time (breeding seasons), and treatments (three types of experimental eggs), using a consistent design of egg rejection experiments (n = 1057 nests; including controls), in areas with potential IP either present (Europe; native populations) or absent (New Zealand; introduced populations). These comparisons benefited from the known length of allopatry (one and a half centuries), with no gene flow between native and introduced populations, which is rarely available in host-parasite systems. Hosts rejected CP at unusually high rates for passerines (up to 60%). CP rejection rates were higher in populations with higher conspecific breeding densities and no risks of IP, supporting the CP hypothesis. IP rejection rates did not covary geographically with IP risk, contradicting the IP hypothesis. High egg rejection rates were maintained in the relatively long-term isolation from IP despite non-trivial rejection costs and errors. These egg rejection patterns, combined with recent findings that these thrushes are currently unsuitable hosts of the obligate parasitic common cuckoo (Cuculus canorus), are in agreement with the hypothesis that the rejection of IP is a by-product of fine-tuned egg discrimination evolved due to CP. Our study highlights the importance of considering both IP and CP simultaneously as potential drivers in the evolution of egg discrimination, and illustrates how populations introduced to novel ecological contexts can provide critical insights

A regional-scale, high resolution dynamical malaria model that accounts for population density, climate and surface hydrology.

Science.gov (United States)

Tompkins, Adrian M; Ermert, Volker

2013-02-18

The relative roles of climate variability and population related effects in malaria transmission could be better understood if regional-scale dynamical malaria models could account for these factors. A new dynamical community malaria model is introduced that accounts for the temperature and rainfall influences on the parasite and vector life cycles which are finely resolved in order to correctly represent the delay between the rains and the malaria season. The rainfall drives a simple but physically based representation of the surface hydrology. The model accounts for the population density in the calculation of daily biting rates. Model simulations of entomological inoculation rate and circumsporozoite protein rate compare well to data from field studies from a wide range of locations in West Africa that encompass both seasonal endemic and epidemic fringe areas. A focus on Bobo-Dioulasso shows the ability of the model to represent the differences in transmission rates between rural and peri-urban areas in addition to the seasonality of malaria. Fine spatial resolution regional integrations for Eastern Africa reproduce the malaria atlas project (MAP) spatial distribution of the parasite ratio, and integrations for West and Eastern Africa show that the model grossly reproduces the reduction in parasite ratio as a function of population density observed in a large number of field surveys, although it underestimates malaria prevalence at high densities probably due to the neglect of population migration. A new dynamical community malaria model is publicly available that accounts for climate and population density to simulate malaria transmission on a regional scale. The model structure facilitates future development to incorporate migration, immunity and interventions.

Paradigms for parasite conservation.

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Dougherty, Eric R; Carlson, Colin J; Bueno, Veronica M; Burgio, Kevin R; Cizauskas, Carrie A; Clements, Christopher F; Seidel, Dana P; Harris, Nyeema C

2016-08-01

Parasitic species, which depend directly on host species for their survival, represent a major regulatory force in ecosystems and a significant component of Earth's biodiversity. Yet the negative impacts of parasites observed at the host level have motivated a conservation paradigm of eradication, moving us farther from attainment of taxonomically unbiased conservation goals. Despite a growing body of literature highlighting the importance of parasite-inclusive conservation, most parasite species remain understudied, underfunded, and underappreciated. We argue the protection of parasitic biodiversity requires a paradigm shift in the perception and valuation of their role as consumer species, similar to that of apex predators in the mid-20th century. Beyond recognizing parasites as vital trophic regulators, existing tools available to conservation practitioners should explicitly account for the unique threats facing dependent species. We built upon concepts from epidemiology and economics (e.g., host-density threshold and cost-benefit analysis) to devise novel metrics of margin of error and minimum investment for parasite conservation. We define margin of error as the risk of accidental host extinction from misestimating equilibrium population sizes and predicted oscillations, while minimum investment represents the cost associated with conserving the additional hosts required to maintain viable parasite populations. This framework will aid in the identification of readily conserved parasites that present minimal health risks. To establish parasite conservation, we propose an extension of population viability analysis for host-parasite assemblages to assess extinction risk. In the direst cases, ex situ breeding programs for parasites should be evaluated to maximize success without undermining host protection. Though parasitic species pose a considerable conservation challenge, adaptations to conservation tools will help protect parasite biodiversity in the face of

Paternity-parasitism trade-offs: a model and test of host-parasite cooperation in an avian conspecific brood parasite.

Science.gov (United States)

Lyon, Bruce E; Hochachka, Wesley M; Eadie, John M

2002-06-01

Efforts to evaluate the evolutionary and ecological dynamics of conspecific brood parasitism in birds and other animals have focused on the fitness costs of parasitism to hosts and fitness benefits to parasites. However, it has been speculated recently that, in species with biparental care, host males might cooperate with parasitic females by allowing access to the host nest in exchange for copulations. We develop a cost-benefit model to explore the conditions under which such host-parasite cooperation might occur. When the brood parasite does not have a nest of her own, the only benefit to the host male is siring some of the parasitic eggs (quasi-parasitism). Cooperation with the parasite is favored when the ratio of host male paternity of his own eggs relative to his paternity of parasitic eggs exceeds the cost of parasitism. When the brood parasite has a nest of her own, a host male can gain additional, potentially more important benefits by siring the high-value, low-cost eggs laid by the parasite in her own nest. Under these conditions, host males should be even more likely to accept parasitic eggs in return for copulations with the parasitic female. We tested these predictions for American coots (Fulica americana), a species with a high frequency of conspecific brood parasitism. Multilocus DNA profiling indicated that host males did not sire any of the parasitic eggs laid in host nests, nor did they sire eggs laid by the parasite in her own nest. We used field estimates of the model parameters from a four-year study of coots to predict the minimum levels of paternity required for the costs of parasitism to be offset by the benefits of mating with brood parasites. Observed levels of paternity were significantly lower than those predicted under a variety of assumptions, and we reject the hypothesis that host males cooperated with parasitic females. Our model clarifies the specific costs and benefits that influence host-parasite cooperation and, more generally

Influence of parasite density and sample storage time on the reliability of Entamoeba histolytica-specific PCR from formalin-fixed and paraffin-embedded tissues.

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Frickmann, Hagen; Tenner-Racz, Klara; Eggert, Petra; Schwarz, Norbert G; Poppert, Sven; Tannich, Egbert; Hagen, Ralf M

2013-12-01

We report on the reliability of polymerase chain reaction (PCR) for the detection of Entamoeba histolytica from formalin-fixed, paraffin-embedded tissue in comparison with microscopy and have determined predictors that may influence PCR results. E. histolytica-specific and Entamoeba dispar-specific real-time PCR and microscopy from adjacent histologic sections were performed using a collection of formalin-fixed, paraffin-embedded tissue specimens obtained from patients with invasive amebiasis. Specimens had been collected during the previous 4 decades. Association of sample age, parasite density, and reliability of PCR was analyzed. E. histolytica PCR was positive in 20 of 34 biopsies (58.8%); 2 of these 20 were microscopically negative for amebae in neighboring tissue sections. PCR was negative in 9 samples with visible amebae in neighboring sections and in 5 samples without visible parasites in neighboring sections. PCR was negative in all specimens that were older than 3 decades. Low parasite counts and sample ages older than 20 years were predictors for false-negative PCR results. All samples were negative for E. dispar DNA. PCR is suitable for the detection of E. histolytica in formalin-fixed, paraffin-embedded tissue samples that are younger than 2 decades and that contain intermediate to high parasite numbers. Negative results in older samples were due to progressive degradation of DNA over time as indicated by control PCRs targeting the human 18S rRNA gene. Moreover, our findings support previous suggestions that only E. histolytica but not E. dispar is responsible for invasive amebiasis.

High prevalence of intestinal zoonotic parasites in dogs from Belgrade, Serbia--short communication.

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Nikolić, Aleksandra; Dimitrijević, Sanda; Katić-Radivojević, Sofija; Klun, Ivana; Bobrć, Branko; Djurković-Djaković, Olgica

2008-09-01

To identify areas of risk for canine-related zoonoses in Serbia, the aim of this study was to provide baseline knowledge about intestinal parasites in 151 dogs (65 household pets, 75 stray and 11 military working dogs) from Belgrade. The following parasites, with their respective prevalences, were detected: Giardia duodenalis (14.6%), Ancylostomatidae (24.5%), Toxocara canis (30.5%), Trichuris vulpis (47.0%) and Taenia-type helminths (6.6%). Of all examined dogs, 75.5% (114/151) were found to harbour at least one parasite species. Of these, mixed infections with up to four species per dog occurred in 44.7% (51/114). Infections with all detected species were significantly higher (p dogs (93.3%) versus household pets (50.8%). Among all parasites, agents with zoonotic potential including Giardia, Ancylostomatidae and Toxocara were detected in 58.3% (88/151) of all examined dogs with a significant difference (p dogs, stray dogs and household pets, respectively). The high prevalence of zoonotic parasites registered in the dog population from a highly urban area in south-eastern Europe indicates a potential risk to human health. Thus, veterinarians should play an important role in helping to prevent or minimise zoonotic transmission.

Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size.

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Rodríguez, Sara M; Valdivia, Nelson

2017-01-01

Parasites are essential components of natural communities, but the factors that generate skewed distributions of parasite occurrences and abundances across host populations are not well understood. Here, we analyse at a seascape scale the spatiotemporal relationships of parasite exposure and host body-size with the proportion of infected hosts (i.e., prevalence) and aggregation of parasite burden across ca. 150 km of the coast and over 22 months. We predicted that the effects of parasite exposure on prevalence and aggregation are dependent on host body-sizes. We used an indirect host-parasite interaction in which migratory seagulls, sandy-shore molecrabs, and an acanthocephalan worm constitute the definitive hosts, intermediate hosts, and endoparasite, respectively. In such complex systems, increments in the abundance of definitive hosts imply increments in intermediate hosts' exposure to the parasite's dispersive stages. Linear mixed-effects models showed a significant, albeit highly variable, positive relationship between seagull density and prevalence. This relationship was stronger for small (cephalothorax length >15 mm) than large molecrabs (analysis of the variance-to-mean ratio of per capita parasite burden showed no relationship between seagull density and mean parasite aggregation across host populations. However, the amount of unexplained variability in aggregation was strikingly higher in larger than smaller intermediate hosts. This unexplained variability was driven by a decrease in the mean-variance scaling in heavily infected large molecrabs. These results show complex interdependencies between extrinsic and intrinsic population attributes on the structure of host-parasite interactions. We suggest that parasite accumulation-a characteristic of indirect host-parasite interactions-and subsequent increasing mortality rates over ontogeny underpin size-dependent host-parasite dynamics.

Global warming will reshuffle the areas of high prevalence and richness of three genera of avian blood parasites.

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Pérez-Rodríguez, Antón; de la Hera, Iván; Fernández-González, Sofía; Pérez-Tris, Javier

2014-08-01

The importance of parasitism for host populations depends on local parasite richness and prevalence: usually host individuals face higher infection risk in areas where parasites are most diverse, and host dispersal to or from these areas may have fitness consequences. Knowing how parasites are and will be distributed in space and time (in a context of global change) is thus crucial from both an ecological and a biological conservation perspective. Nevertheless, most research articles focus just on elaborating models of parasite distribution instead of parasite diversity. We produced distribution models of the areas where haemosporidian parasites are currently highly diverse (both at community and at within-host levels) and prevalent among Iberian populations of a model passerine host: the blackcap Sylvia atricapilla; and how these areas are expected to vary according to three scenarios of climate change. On the basis of these models, we analysed whether variation among populations in parasite richness or prevalence are expected to remain the same or change in the future, thereby reshuffling the geographic mosaic of host-parasite interactions as we observe it today. Our models predict a rearrangement of areas of high prevalence and richness of parasites in the future, with Haemoproteus and Leucocytozoon parasites (today the most diverse genera in blackcaps) losing areas of high diversity and Plasmodium parasites (the most virulent ones) gaining them. Likewise, the prevalence of multiple infections and parasite infracommunity richness would be reduced. Importantly, differences among populations in the prevalence and richness of parasites are expected to decrease in the future, creating a more homogeneous parasitic landscape. This predicts an altered geographic mosaic of host-parasite relationships, which will modify the interaction arena in which parasite virulence evolves. © 2014 John Wiley & Sons Ltd.

High rate of adaptation of mammalian proteins that interact with Plasmodium and related parasites

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Telis, Natalie; Petrov, Dmitri A.

2017-01-01

Plasmodium parasites, along with their Piroplasm relatives, have caused malaria-like illnesses in terrestrial mammals for millions of years. Several Plasmodium-protective alleles have recently evolved in human populations, but little is known about host adaptation to blood parasites over deeper evolutionary timescales. In this work, we analyze mammalian adaptation in ~500 Plasmodium- or Piroplasm- interacting proteins (PPIPs) manually curated from the scientific literature. We show that (i) PPIPs are enriched for both immune functions and pleiotropy with other pathogens, and (ii) the rate of adaptation across mammals is significantly elevated in PPIPs, compared to carefully matched control proteins. PPIPs with high pathogen pleiotropy show the strongest signatures of adaptation, but this pattern is fully explained by their immune enrichment. Several pieces of evidence suggest that blood parasites specifically have imposed selection on PPIPs. First, even non-immune PPIPs that lack interactions with other pathogens have adapted at twice the rate of matched controls. Second, PPIP adaptation is linked to high expression in the liver, a critical organ in the parasite life cycle. Finally, our detailed investigation of alpha-spectrin, a major red blood cell membrane protein, shows that domains with particularly high rates of adaptation are those known to interact specifically with P. falciparum. Overall, we show that host proteins that interact with Plasmodium and Piroplasm parasites have experienced elevated rates of adaptation across mammals, and provide evidence that some of this adaptation has likely been driven by blood parasites. PMID:28957326

High-Power-Density, High-Energy-Density Fluorinated Graphene for Primary Lithium Batteries

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Guiming Zhong

2018-03-01

Full Text Available Li/CFx is one of the highest-energy-density primary batteries; however, poor rate capability hinders its practical applications in high-power devices. Here we report a preparation of fluorinated graphene (GFx with superior performance through a direct gas fluorination method. We find that the so-called “semi-ionic” C-F bond content in all C-F bonds presents a more critical impact on rate performance of the GFx in comparison with sp2 C content in the GFx, morphology, structure, and specific surface area of the materials. The rate capability remains excellent before the semi-ionic C-F bond proportion in the GFx decreases. Thus, by optimizing semi-ionic C-F content in our GFx, we obtain the optimal x of 0.8, with which the GF0.8 exhibits a very high energy density of 1,073 Wh kg−1 and an excellent power density of 21,460 W kg−1 at a high current density of 10 A g−1. More importantly, our approach opens a new avenue to obtain fluorinated carbon with high energy densities without compromising high power densities.

Parasite fitness traits under environmental variation: disentangling the roles of a chytrid's immediate host and external environment.

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Van den Wyngaert, Silke; Vanholsbeeck, Olivier; Spaak, Piet; Ibelings, Bas W

2014-10-01

Parasite environments are heterogeneous at different levels. The first level of variability is the host itself. The second level represents the external environment for the hosts, to which parasites may be exposed during part of their life cycle. Both levels are expected to affect parasite fitness traits. We disentangle the main and interaction effects of variation in the immediate host environment, here the diatom Asterionella formosa (variables host cell volume and host condition through herbicide pre-exposure) and variation in the external environment (variables host density and acute herbicide exposure) on three fitness traits (infection success, development time and reproductive output) of a chytrid parasite. Herbicide exposure only decreased infection success in a low host density environment. This result reinforces the hypothesis that chytrid zoospores use photosynthesis-dependent chemical cues to locate its host. At high host densities, chemotaxis becomes less relevant due to increasing chance contact rates between host and parasite, thereby following the mass-action principle in epidemiology. Theoretical support for this finding is provided by an agent-based simulation model. The immediate host environment (cell volume) substantially affected parasite reproductive output and also interacted with the external herbicide exposed environment. On the contrary, changes in the immediate host environment through herbicide pre-exposure did not increase infection success, though it had subtle effects on zoospore development time and reproductive output. This study shows that both immediate host and external environment as well as their interaction have significant effects on parasite fitness. Disentangling these effects improves our understanding of the processes underlying parasite spread and disease dynamics.

Parasite invasion following host reintroduction: a case study of Yellowstone's wolves.

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Almberg, Emily S; Cross, Paul C; Dobson, Andrew P; Smith, Douglas W; Hudson, Peter J

2012-10-19

Wildlife reintroductions select or treat individuals for good health with the expectation that these individuals will fare better than infected animals. However, these individuals, new to their environment, may also be particularly susceptible to circulating infections and this may result in high morbidity and mortality, potentially jeopardizing the goals of recovery. Here, using the reintroduction of the grey wolf (Canis lupus) into Yellowstone National Park as a case study, we address the question of how parasites invade a reintroduced population and consider the impact of these invasions on population performance. We find that several viral parasites rapidly invaded the population inside the park, likely via spillover from resident canid species, and we contrast these with the slower invasion of sarcoptic mange, caused by the mite Sarcoptes scabiei. The spatio-temporal patterns of mange invasion were largely consistent with patterns of host connectivity and density, and we demonstrate that the area of highest resource quality, supporting the greatest density of wolves, is also the region that appears most susceptible to repeated disease invasion and parasite-induced declines. The success of wolf reintroduction appears not to have been jeopardized by infectious disease, but now shows signs of regulation or limitation modulated by parasites.

Parasite invasion following host reintroduction: a case of Yellowstone’s wolves

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Cross, Paul C.; Almberg, Emily S.; Dobson, Andrew P.; Smith, Douglas W.; Hudson, Peter J.

2012-01-01

Wildlife reintroductions select or treat individuals for good health with the expectation that these individuals will fare better than infected animals. However, these individuals, new to their environment, may also be particularly susceptible to circulating infections and this may result in high morbidity and mortality, potentially jeopardizing the goals of recovery. Here, using the reintroduction of the grey wolf (Canis lupus) into Yellowstone National Park as a case study, we address the question of how parasites invade a reintroduced population and consider the impact of these invasions on population performance. We find that several viral parasites rapidly invaded the population inside the park, likely via spillover from resident canid species, and we contrast these with the slower invasion of sarcoptic mange, caused by the mite Sarcoptes scabiei. The spatio-temporal patterns of mange invasion were largely consistent with patterns of host connectivity and density, and we demonstrate that the area of highest resource quality, supporting the greatest density of wolves, is also the region that appears most susceptible to repeated disease invasion and parasite-induced declines. The success of wolf reintroduction appears not to have been jeopardized by infectious disease, but now shows signs of regulation or limitation modulated by parasites.

Effect of ectoparasite infestation density and life history stages on the swimming performance of Atlantic salmon Salmo salar

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Samantha Bui

2016-06-01

Full Text Available To overcome sustainability obstacles and improve operations, the Atlantic salmon farming industry is testing novel approaches to production. Redistributing farm sites to offshore locations is one such solution; however, tolerance to high-current velocity sites must be considered, particularly if fish health status is compromised by parasites. We tested the effect of parasite density and life-history stage on the swimming performance of Atlantic salmon Salmo salar using a swim flume. Salmon with 3 different salmon lice Lepeophtheirus salmonis densities (0, 0.02 � 0.01 and 0.11 � 0.01 lice cm-2 [mean � SE] were tested across the 4 major life-history stages of lice (copepodid, chalimus, pre-adult and adult for critical swimming performance (Ucrit. Salmon Ucrit declined slightly by a mean of 0.04 to 0.10 body lengths s-1 with high parasite densities compared to uninfested and low densities, across the lice stages, while progression through the parasite life-history stages had little effect on swimming performance. Our results suggest that increasing infestation density of salmon lice incurs negative fitness consequences for farmed Atlantic salmon held in high-current velocity sites, with little difference in costs associated with attachment by different life-history stages of the lice.

Regulation of Population Densities of Heterodera cajani and Other Plant-Parasitic Nematodes by Crop Rotations on Vertisols, in Semi-Arid Tropical Production Systems in India

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Sharma, S. B.; Rego, T. J.; Mohiuddin, M.; Rao, V. N.

1996-01-01

The significance of double crop (intercrop and sequential crop), single crop (rainy season crop fallow from June to September), and rotations on densities of Heterodera cajani, Helicotylenchus retusus, and Rotylenchulus reniformis was studied on Vertisol (Typic Pellusterts) between 1987 and 1993. Cowpea (Vigna sinensis), mungbean (Phaseolus aureus), and pigeonpea (Cajanus cajan) greatly increased the population densities of H. cajani and suppressed the population densities of other plant-parasitic nematodes. Mean population densities of H. cajani were about 8 times lower in single crop systems than in double crop systems, with pigeonpea as a component intercrop. Plots planted to sorghum, safflower, and chickpea in the preceding year contained fewer H. cajani eggs and juveniles than did plots previously planted to pigeonpea, cowpea, or mungbean. Continuous cropping of sorghum in the rainy season and safflower in the post-rainy season markedly reduced the population density of H. cajani. Sorghum, safflower, and chickpea favored increased population densities of H. retusus. Adding cowpea to the system resulted in a significant increase in the densities of R. reniformis. Mean densities of total plant-parasitic nematodes were three times greater in double crop systems, with pigeonpea as a component intercrop than in single crop systems with rainy season fallow component. Cropping systems had a regulatory effect on the nematode populations and could be an effective nematode management tactic. Intercropping of sorghum with H. cajani tolerant pigeonpea could be effective in increasing the productivity of traditional production systems in H. cajani infested regions. PMID:19277141

Highly rearranged mitochondrial genome in Nycteria parasites (Haemosporidia) from bats.

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Karadjian, Gregory; Hassanin, Alexandre; Saintpierre, Benjamin; Gembu Tungaluna, Guy-Crispin; Ariey, Frederic; Ayala, Francisco J; Landau, Irene; Duval, Linda

2016-08-30

Haemosporidia parasites have mostly and abundantly been described using mitochondrial genes, and in particular cytochrome b (cytb). Failure to amplify the mitochondrial cytb gene of Nycteria parasites isolated from Nycteridae bats has been recently reported. Bats are hosts to a diverse and profuse array of Haemosporidia parasites that remain largely unstudied. There is a need to obtain more molecular data from chiropteran parasites. Such data would help to better understand the evolutionary history of Haemosporidia, which notably include the Plasmodium parasites, malaria's agents. We use next-generation sequencing to obtain the complete mitochondrial genome of Nycteria parasites from African Nycteris grandis (Nycteridae) and Rhinolophus alcyone (Rhinolophidae) and Asian Megaderma spasma (Megadermatidae). We report four complete mitochondrial genomes, including two rearranged mitochondrial genomes within Haemosporidia. Our results open outlooks into potentially undiscovered Haemosporidian diversity.

Parasites affect food web structure primarily through increased diversity and complexity.

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Jennifer A Dunne

Full Text Available Comparative research on food web structure has revealed generalities in trophic organization, produced simple models, and allowed assessment of robustness to species loss. These studies have mostly focused on free-living species. Recent research has suggested that inclusion of parasites alters structure. We assess whether such changes in network structure result from unique roles and traits of parasites or from changes to diversity and complexity. We analyzed seven highly resolved food webs that include metazoan parasite data. Our analyses show that adding parasites usually increases link density and connectance (simple measures of complexity, particularly when including concomitant links (links from predators to parasites of their prey. However, we clarify prior claims that parasites "dominate" food web links. Although parasites can be involved in a majority of links, in most cases classic predation links outnumber classic parasitism links. Regarding network structure, observed changes in degree distributions, 14 commonly studied metrics, and link probabilities are consistent with scale-dependent changes in structure associated with changes in diversity and complexity. Parasite and free-living species thus have similar effects on these aspects of structure. However, two changes point to unique roles of parasites. First, adding parasites and concomitant links strongly alters the frequency of most motifs of interactions among three taxa, reflecting parasites' roles as resources for predators of their hosts, driven by trophic intimacy with their hosts. Second, compared to free-living consumers, many parasites' feeding niches appear broader and less contiguous, which may reflect complex life cycles and small body sizes. This study provides new insights about generic versus unique impacts of parasites on food web structure, extends the generality of food web theory, gives a more rigorous framework for assessing the impact of any species on trophic

Relationship between thermal loading and parasitism in the mosquitofish

International Nuclear Information System (INIS)

Aho, J.M.; Gibbons, J.W.; Esch, G.W.

1976-01-01

The relationship between thermal loading and parasitism was examined in 980 mosquitofish, Gambusia affinis, taken from areas of varying thermal conditions at the Savannah River Plant (SRP) near Aiken, S. C. Collections were made at 2-week intervals from May to August 1974 and again from January to February 1975. The metacercaria of two strigeid trematodes, Ornithodiplostomum ptychocheilus and Diplostomum scheuringi were the only species of parasites recovered. Ornithodiplostomum ptychocheilus was always found encysted in the brain and eyes, whereas D. scheuringi was restricted exclusively to the body cavity. The density of the body-cavity parasite was highest in fish from areas of ambient temperatures and declined in fish from areas with higher water temperatures. The density of the brain parasite, on the other hand, was higher in fish from areas directly receiving thermal effluent than in fish from ambient-temperature areas. The body-cavity parasite was absent from mosquitofish from Pond C, but the infection percentages were relatively consistent in fish from other areas in the Par Pond system regardless of water temperature. The brain metacercaria were recovered from 95 percent of fish from Pond C

Helminth parasites alter protection against Plasmodium infection.

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Salazar-Castañon, Víctor H; Legorreta-Herrera, Martha; Rodriguez-Sosa, Miriam

2014-01-01

More than one-third of the world's population is infected with one or more helminthic parasites. Helminth infections are prevalent throughout tropical and subtropical regions where malaria pathogens are transmitted. Malaria is the most widespread and deadliest parasitic disease. The severity of the disease is strongly related to parasite density and the host's immune responses. Furthermore, coinfections between both parasites occur frequently. However, little is known regarding how concomitant infection with helminths and Plasmodium affects the host's immune response. Helminthic infections are frequently massive, chronic, and strong inductors of a Th2-type response. This implies that infection by such parasites could alter the host's susceptibility to subsequent infections by Plasmodium. There are a number of reports on the interactions between helminths and Plasmodium; in some, the burden of Plasmodium parasites increased, but others reported a reduction in the parasite. This review focuses on explaining many of these discrepancies regarding helminth-Plasmodium coinfections in terms of the effects that helminths have on the immune system. In particular, it focuses on helminth-induced immunosuppression and the effects of cytokines controlling polarization toward the Th1 or Th2 arms of the immune response.

The high resolution melting analysis (HRM) as a molecular tool for monitoring parasites of the wildlife.

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Héritier, Laurent; Verneau, Olivier; Breuil, Gregory; Meistertzheim, Anne-Leila

2017-04-01

In an interconnected world, the international pet trade on wild animals is becoming increasingly important. As a consequence, non-native parasite species are introduced, which affect the health of wildlife and contribute to the loss of biodiversity. Because the investigation of parasite diversity within vulnerable host species implies the molecular identification of large samples of parasite eggs, the sequencing of DNA barcodes is time-consuming and costly. Thereby, the objectives of our study were to apply the high resolution melting (HRM) approach for species determination from pools of parasite eggs. Molecular assays were validated on flatworm parasites (polystomes) infecting the Mediterranean pond turtle Mauremys leprosa and the invasive red-eared slider Trachemys scripta elegans in French natural environments. HRM analysis results indicated that double or multiple parasitic infections could be detected from wild animal populations. They also showed that the cycle of parasite eggs production was not regular over time and may depend on several factors, among which the ecological niche and the target species. Thereby, monitoring parasites from wild endangered animals implies periodic parasitological surveys to avoid false negative diagnostics, based solely on eggs production.

Overview on the effects of parasites on fish health

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Iwanowicz, D.D.; Cipriano, R.C.; Bruckner, A.W.; Shchelkunov, I.S.

2011-01-01

It is believed by many that parasites are only as important as the fish they infect. Parasites are ubiquitous, primarily surviving in a dynamic equilibrium with their host(s) and they are often overlooked in fish health assessments. Changes in the environment, both anthropogenic and environmental, can alter the parasite/host equilibrium and cause disease or mortality in fish. Therefore it is imperative that we have knowledge of both parasites and parasitic communities within a given population. When fish kills occur, it can often be associated with changes in parasite density and community composition. Often the damage associated with these fish is relative to the rate of infestation with the parasite; a fish that is lightly infected will show few signs of the parasite, while a heavily infected fish may become physiologically impaired and even die. Parasites can cause mechanical damage (fusion of gill lamellae, tissue replacement), physiological damage (cell proliferation, immunomodulation, detrimental behavioral responses, altered growth) and reproductive damage. As parasitism is the most common lifestyle on the planet, understanding its role in the environment may help researchers understand changes in a given fish population or stream ecosystem.

microRNA profiling in the zoonotic parasite Echinococcus canadensis using a high-throughput approach.

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Macchiaroli, Natalia; Cucher, Marcela; Zarowiecki, Magdalena; Maldonado, Lucas; Kamenetzky, Laura; Rosenzvit, Mara Cecilia

2015-02-06

microRNAs (miRNAs), a class of small non-coding RNAs, are key regulators of gene expression at post-transcriptional level and play essential roles in fundamental biological processes such as development and metabolism. The particular developmental and metabolic characteristics of cestode parasites highlight the importance of studying miRNA gene regulation in these organisms. Here, we perform a comprehensive analysis of miRNAs in the parasitic cestode Echinococcus canadensis G7, one of the causative agents of the neglected zoonotic disease cystic echinococcosis. Small RNA libraries from protoscoleces and cyst walls of E. canadensis G7 and protoscoleces of E. granulosus sensu stricto G1 were sequenced using Illumina technology. For miRNA prediction, miRDeep2 core algorithm was used. The output list of candidate precursors was manually curated to generate a high confidence set of miRNAs. Differential expression analysis of miRNAs between stages or species was estimated with DESeq. Expression levels of selected miRNAs were validated using poly-A RT-qPCR. In this study we used a high-throughput approach and found transcriptional evidence of 37 miRNAs thus expanding the miRNA repertoire of E. canadensis G7. Differential expression analysis showed highly regulated miRNAs between life cycle stages, suggesting a role in maintaining the features of each developmental stage or in the regulation of developmental timing. In this work we characterize conserved and novel Echinococcus miRNAs which represent 30 unique miRNA families. Here we confirmed the remarkable loss of conserved miRNA families in E. canadensis, reflecting their low morphological complexity and high adaptation to parasitism. We performed the first in-depth study profiling of small RNAs in the zoonotic parasite E. canadensis G7. We found that miRNAs are the preponderant small RNA silencing molecules, suggesting that these small RNAs could be an essential mechanism of gene regulation in this species. We also

The Romanomermis iyengari parasite for Anopheles pseudopunctipennis suppression in natural habitats in Oaxaca State, Mexico

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Santamarina Mijares Alberto

1999-01-01

Full Text Available In September and November 1996 Romanomermis iyengari Welch, a parasite of larval mosquitoes, was released in 44 natural larval habitat sites of Anopheles pseudopunctipennis Theobald in an attempt to reduce the larval populations of this important malaria vector. The selected treatment sites ranged in size from 5 to 500 m². The study was carried out in Pochutla District of Oaxaca State, on the Pacific coast of Mexico. Chemical pesticides to reduce vector populations have been the principal tool in malaria suppression campaigns. However, the excessive use of these chemicals has created pesticide resistance and other serious collateral problems. Therefore, a biological control project using agents that are pathogens of Anopheles larvae was initiated in 1996. The principal objective was to establish mass rearing capacities for R. iyengari. Detailed methodology for rearing and introducing these nematodes into mosquito larval habitats was established at the National Polytechnic Institute of Oaxaca State. Before application of the parasites to larval habitats, site characteristics were determined, including size, depth, aquatic vegetation, salinity, pH, conductivity, temperature, and pretreatment larval density. With a compressed air sprayer, infective mermithid parasites were released at rates of either 2000 or 3000/m², and the parasites produced high levels of infection. Anopheles populations were sampled 72 h posttreatment, and the larvae obtained were taken to the laboratory and examined through microscopic dissection to determine infection levels and mean parasitism. Nematode parasitism ranged from 85 to 100% at all the treatment sites, even though no previous information concerning field parasitism of An. pseudopunctipennis by R. iyengari has been reported. In addition, a significant reduction of mosquito larval density at the treatment sites was found five days after the nematode application. Levels of parasitism were indicative of the number

Conspecific brood parasitism and egg quality in blue tits Cyanistes caeruleus

NARCIS (Netherlands)

Vedder, Oscar; Kingma, Sjouke-Anne; Engelhardt, Nikolaus von; Korsten, Peter; Groothuis, Ton G.G.; Komdeur, Jan

Laying eggs in nests of unrelated conspecific pairs to parasitize their parental care is a common phenomenon in birds. In blue tits Cyanistes caeruleus such conspecific brood parasitism (CBP) has never been reported in the literature. However, in a situation where breeding density was extremely

A highly rearranged mitochondrial genome in Nycteria parasites (Haemosporidia) from bats

OpenAIRE

Karadjian , Gregory; Hassanin , Alexandre; Saintpierre , Benjamin; Gembu Tungaluna , Guy-Crispin; Ariey , Frederic; Ayala , Francisco J.; Landau , Irene; Duval , Linda

2016-01-01

International audience; Haemosporidia parasites have mostly and abundantly been described using mitochondrial genes, and in particular cytochrome b (cytb). Failure to amplify the mitochondrial cytb gene of Nycteria parasites isolated from Nycteridae bats has been recently reported. Bats are hosts to a diverse and profuse array of Haemosporidia parasites that remain largely unstudied. There is a need to obtain more molecular data from chiropteran parasites. Such data would help to better under...

Variation in apoptosis mechanisms employed by malaria parasites: the roles of inducers, dose dependence and parasite stages

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Matthews Holly

2012-08-01

Full Text Available Abstract Background Plasmodium berghei ookinetes exhibit an apoptotic phenotype when developing within the mosquito midgut lumen or when cultured in vitro. Markers of apoptosis increase when they are exposed to nitric oxide or reactive oxygen species but high concentrations of hydrogen peroxide cause death without observable signs of apoptosis. Chloroquine and other drugs have been used to induce apoptosis in erythrocytic stages of Plasmodium falciparum and to formulate a putative pathway involving cysteine protease activation and mitochondrial membrane permeabilization; initiated, at least in the case of chloroquine, after its accumulation in the digestive vacuole causes leakage of the vacuole contents. The lack of a digestive vacuole in ookinetes prompted the investigation of the effect of chloroquine and staurosporine on this stage of the life cycle. Finally, the suggestion that apoptosis may have evolved as a strategy employed by ookinetes to increase the fitness of surviving parasites was explored by determining whether increasing the ecological triggers parasite density and nutrient depletion induced apoptosis. Methods Ookinetes were grown in culture then either exposed to hydrogen peroxide, chloroquine or staurosporine, or incubated at different densities and in different media. The proportion of ookinetes displaying positive markers for apoptosis in treated samples was compared with controls and results were analyzed using analysis of variance followed by a Turkey’s test, or a Kruskal-Wallis test as appropriate. Results Hydrogen peroxide below 50 μM triggered apoptosis but cell membranes were rapidly compromised by higher concentrations, and the mode of death could not be defined. Both chloroquine and staurosporine cause a significant increase in ookinetes with condensed chromatin, caspase-like activity and, in the case of chloroquine, phosphatidylserine translocation and DNA fragmentation (not investigated for staurosporine. However

Importing low-density ideas to high-density revitalisation

DEFF Research Database (Denmark)

Arnholtz, Jens; Ibsen, Christian Lyhne; Ibsen, Flemming

2016-01-01

Why did union officials from a high-union-density country like Denmark choose to import an organising strategy from low-density countries such as the US and the UK? Drawing on in-depth interviews with key union officials and internal documents, the authors of this article argue two key points. Fi...

Within- and among-family variation in parasite load and parasite-induced mortality in the land snail Arianta arbustorum, a host of parasitic mites.

Science.gov (United States)

Schüpbach, Hans Ulrich; Baur, Bruno

2010-08-01

Variation in host susceptibility and parasite-induced mortality are preconditions for parasite-related selection on host populations. In terrestrial gastropods, variation in resistance against ectoparasite infection is poorly understood. We examined the within- and among-family variation in parasite load in full-siblings of the land snail Arianta arbustorum experimentally infected with Riccardoella limacum , a mite living in the mantle cavity of helicid land snails. We also quantified the influence of family origin and host size on parasite load and calculated its heritability (h(2)). Furthermore, we examined the influence of parasite load, snail size, and family origin on host winter mortality, an important life-history trait of A. arbustorum . Parasite load was heritable (h(2) = 0.63). In infected snails, parasite load was affected by family origin and increased with increasing shell size. Host mortality during hibernation increased with increasing parasite load and differed among families, but was not affected by snail size. Our results show high among-family variation both in resistance against ectoparasite infection and in host winter mortality. Furthermore, we show that parasite load is linked to snail size, which suggests that the proliferation of R. limacum is limited by resources provided by A. arbustorum .

Evaluation of a novel magneto-optical method for the detection of malaria parasites.

Directory of Open Access Journals (Sweden)

Agnes Orbán

Full Text Available Improving the efficiency of malaria diagnosis is one of the main goals of current malaria research. We have recently developed a magneto-optical (MO method which allows high-sensitivity detection of malaria pigment (hemozoin crystals in blood via the magnetically induced rotational motion of the hemozoin crystals. Here, we evaluate this MO technique for the detection of Plasmodium falciparum in infected erythrocytes using in-vitro parasite cultures covering the entire intraerythrocytic life cycle. Our novel method detected parasite densities as low as ∼ 40 parasites per microliter of blood (0.0008% parasitemia at the ring stage and less than 10 parasites/µL (0.0002% parasitemia in the case of the later stages. These limits of detection, corresponding to approximately 20 pg/µL of hemozoin produced by the parasites, exceed that of rapid diagnostic tests and compete with the threshold achievable by light microscopic observation of blood smears. The MO diagnosis requires no special training of the operator or specific reagents for parasite detection, except for an inexpensive lysis solution to release intracellular hemozoin. The devices can be designed to a portable format for clinical and in-field tests. Besides testing its diagnostic performance, we also applied the MO technique to investigate the change in hemozoin concentration during parasite maturation. Our preliminary data indicate that this method may offer an efficient tool to determine the amount of hemozoin produced by the different parasite stages in synchronized cultures. Hence, it could eventually be used for testing the susceptibility of parasites to antimalarial drugs.

High Energy Density Laboratory Astrophysics

CERN Document Server

Lebedev, Sergey V

2007-01-01

During the past decade, research teams around the world have developed astrophysics-relevant research utilizing high energy-density facilities such as intense lasers and z-pinches. Every two years, at the International conference on High Energy Density Laboratory Astrophysics, scientists interested in this emerging field discuss the progress in topics covering: - Stellar evolution, stellar envelopes, opacities, radiation transport - Planetary Interiors, high-pressure EOS, dense plasma atomic physics - Supernovae, gamma-ray bursts, exploding systems, strong shocks, turbulent mixing - Supernova remnants, shock processing, radiative shocks - Astrophysical jets, high-Mach-number flows, magnetized radiative jets, magnetic reconnection - Compact object accretion disks, x-ray photoionized plasmas - Ultrastrong fields, particle acceleration, collisionless shocks. These proceedings cover many of the invited and contributed papers presented at the 6th International Conference on High Energy Density Laboratory Astrophys...

High-density multicore fibers

DEFF Research Database (Denmark)

Takenaga, K.; Matsuo, S.; Saitoh, K.

2016-01-01

High-density single-mode multicore fibers were designed and fabricated. A heterogeneous 30-core fiber realized a low crosstalk of −55 dB. A quasi-single-mode homogeneous 31-core fiber attained the highest core count as a single-mode multicore fiber.......High-density single-mode multicore fibers were designed and fabricated. A heterogeneous 30-core fiber realized a low crosstalk of −55 dB. A quasi-single-mode homogeneous 31-core fiber attained the highest core count as a single-mode multicore fiber....

High-field, high-density tokamak power reactor

International Nuclear Information System (INIS)

Cohn, D.R.; Cook, D.L.; Hay, R.D.; Kaplan, D.; Kreischer, K.; Lidskii, L.M.; Stephany, W.; Williams, J.E.C.; Jassby, D.L.; Okabayashi, M.

1977-11-01

A conceptual design of a compact (R 0 = 6.0 m) high power density (average P/sub f/ = 7.7 MW/m 3 ) tokamak demonstration power reactor has been developed. High magnetic field (B/sub t/ = 7.4 T) and moderate elongation (b/a = 1.6) permit operation at the high density (n(0) approximately 5 x 10 14 cm -3 ) needed for ignition in a relatively small plasma, with a spatially-averaged toroidal beta of only 4%. A unique design for the Nb 3 Sn toroidal-field magnet system reduces the stress in the high-field trunk region, and allows modularization for simpler disassembly. The modest value of toroidal beta permits a simple, modularized plasma-shaping coil system, located inside the TF coil trunk. Heating of the dense central plasma is attained by the use of ripple-assisted injection of 120-keV D 0 beams. The ripple-coil system also affords dynamic control of the plasma temperature during the burn period. A FLIBE-lithium blanket is designed especially for high-power-density operation in a high-field environment, and gives an overall tritium breeding ratio of 1.05 in the slowly pumped lithium

High density harp for SSCL linac

International Nuclear Information System (INIS)

Fritsche, C.T.; Krogh, M.L.; Crist, C.E.

1993-01-01

AlliedSignal Inc., Kansas City Division, and the Superconducting Super Collider Laboratory (SSCL) are collaboratively developing a high density harp for the SSCL linac. This harp is designed using hybrid microcircuit (HMC) technology to obtain a higher wire density than previously available. The developed harp contains one hundred twenty-eight 33-micron-diameter carbon wires on 0.38-mm centers. The harp features an onboard broken wire detection circuit. Carbon wire preparation and attachment processes were developed. High density surface mount connectors were located. The status of high density harp development will be presented along with planned future activities

High density harp for SSCL linac

International Nuclear Information System (INIS)

Fritsche, C.T.; Krogh, M.L.

1993-05-01

AlliedSignal Inc., Kansas City Division, and the Superconducting Super Collider Laboratory (SSCL) are collaboratively developing a high density harp for the SSCL linac. This harp is designed using hybrid microcircuit (HMC) technology to obtain a higher wire density than previously available. The developed harp contains one hundred twenty-eight 33-micron-diameter carbon wires on 0.38-mm centers. The harp features an onboard broken wire detection circuit. Carbon wire preparation and attachment processes were developed. High density surface mount connectors were located. The status of high density harp development will be presented along with planned future activities

High density dispersion fuel

International Nuclear Information System (INIS)

Hofman, G.L.

1996-01-01

A fuel development campaign that results in an aluminum plate-type fuel of unlimited LEU burnup capability with an uranium loading of 9 grams per cm 3 of meat should be considered an unqualified success. The current worldwide approved and accepted highest loading is 4.8 g cm -3 with U 3 Si 2 as fuel. High-density uranium compounds offer no real density advantage over U 3 Si 2 and have less desirable fabrication and performance characteristics as well. Of the higher-density compounds, U 3 Si has approximately a 30% higher uranium density but the density of the U 6 X compounds would yield the factor 1.5 needed to achieve 9 g cm -3 uranium loading. Unfortunately, irradiation tests proved these peritectic compounds have poor swelling behavior. It is for this reason that the authors are turning to uranium alloys. The reason pure uranium was not seriously considered as a dispersion fuel is mainly due to its high rate of growth and swelling at low temperatures. This problem was solved at least for relatively low burnup application in non-dispersion fuel elements with small additions of Si, Fe, and Al. This so called adjusted uranium has nearly the same density as pure α-uranium and it seems prudent to reconsider this alloy as a dispersant. Further modifications of uranium metal to achieve higher burnup swelling stability involve stabilization of the cubic γ phase at low temperatures where normally α phase exists. Several low neutron capture cross section elements such as Zr, Nb, Ti and Mo accomplish this in various degrees. The challenge is to produce a suitable form of fuel powder and develop a plate fabrication procedure, as well as obtain high burnup capability through irradiation testing

High regression rate, high density hybrid fuels, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This SBIR program will investigate high energy density novel nanofuels combined with high density binders for use with an N2O oxidizer. Terves has developed...

Parasite load induces progressive spleen architecture breakage and impairs cytokine mRNA expression in Leishmania infantum-naturally infected dogs.

Science.gov (United States)

Cavalcanti, Amanda S; Ribeiro-Alves, Marcelo; Pereira, Luiza de O R; Mestre, Gustavo Leandro; Ferreira, Anna Beatriz Robottom; Morgado, Fernanda N; Boité, Mariana C; Cupolillo, Elisa; Moraes, Milton O; Porrozzi, Renato

2015-01-01

Canine Visceral Leishmaniasis (CVL) shares many aspects with the human disease and dogs are considered the main urban reservoir of L. infantum in zoonotic VL. Infected dogs develop progressive disease with a large clinical spectrum. A complex balance between the parasite and the genetic/immunological background of the host are decisive for infection evolution and clinical outcome. This study comprised 92 Leishmania infected mongrel dogs of various ages from Mato Grosso, Brazil. Spleen samples were collected for determining parasite load, humoral response, cytokine mRNA expression and histopathology alterations. By real-time PCR for the ssrRNA Leishmania gene, two groups were defined; a low (lowP, n = 46) and a high parasite load groups (highP, n = 42). When comparing these groups, results show variable individual humoral immune response with higher specific IgG production in infected animals but with a notable difference in CVL rapid test optical densities (DPP) between highP and lowP groups. Splenic architecture disruption was characterized by disorganization of white pulp, more evident in animals with high parasitism. All cytokine transcripts in spleen were less expressed in highP than lowP groups with a large heterogeneous variation in response. Individual correlation analysis between cytokine expression and parasite load revealed a negative correlation for both pro-inflammatory cytokines: IFNγ, IL-12, IL-6; and anti-inflammatory cytokines: IL-10 and TGFβ. TNF showed the best negative correlation (r2 = 0.231; pdogs with high parasite load associated with a structural modification in the splenic lymphoid micro-architecture. We also discuss the possible mechanism responsible for the uncontrolled parasite growth and clinical outcome.

Criticality of Parasitic Disease Transmission in a Diffusive Population

International Nuclear Information System (INIS)

He Minhua; Zhang Duanming; Yin Yanping; Chen Zhiyuan; Pan Guijun

2008-01-01

Through using the methods of finite-size effect and short time dynamic scaling, we study the critical behavior of parasitic disease spreading process in a diffusive population mediated by a static vector environment. Through comprehensive analysis of parasitic disease spreading we find that this model presents a dynamical phase transition from disease-free state to endemic state with a finite population density. We determine the critical population density, above which the system reaches an epidemic spreading stationary state. We also perform a scaling analysis to determine the order parameter and critical relaxation exponents. The results show that the model does not belong to the usual directed percolation universality class and is compatible with the class of directed percolation with diffusive and conserved fields

One Health: parasites and beyond…

OpenAIRE

Blake, DP; Betson, ME

2016-01-01

The field of parasitism is broad, encompassing relationships between organisms where one benefits at the expense of another. Traditionally the discipline focuses on eukaryotes, with the study of bacteria and viruses complementary but distinct. Nonetheless, parasites vary in size and complexity from single celled protozoa, to enormous plants like those in the genus Rafflesia. Lifecycles range from obligate intracellular to extensive exoparasitism. Examples of parasites include high profile med...

Parasitism and super parasitism of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) on Sitotroga cerealella (Oliver) (Lepidoptera: Gelechiidae) eggs

International Nuclear Information System (INIS)

Moreira, Marciene D.; Torres, Jorge B.

2009-01-01

The parasitoid Trichogramma has been used worldwide as biological control agent due to its wide geographic distribution, high specialization and efficacy against many lepidopteran pests. Biological and behavioral traits of Trichogramma pretiosum Riley parasitizing Sitotroga cerealella (Oliver) eggs were studied aiming to a better understanding of the Results from parasitism and super parasitism. The variables investigated were: host acceptance and contact time by T. pretiosum on parasitized host, percentage of parasitoid emergence, number of deformed individuals produced, egg-adult period, sex ratio, offspring female body size and longevity, and number of S. cerealella eggs parasitized/female. Parasitism rejection was observed on parasitized host eggs after 24, 72 and 120h of parasitism. The rejection was higher for eggs parasitized after 72h and 120h of parasitism as compared to the eggs after 24h of parasitism. T. pretiosum contact time on eggs after 24h of parasitism was greater than on 72 and 120h. The offspring produced from hosts from which a single parasitoid emerged were larger, exhibited no deformities and greater capacity of parasitism, different from those produced from eggs where two parasitoids emerged. Offspring longevity, however, was similar for females emerged from hosts from which one or two adults emerged. In Conclusion, T. pretiosum was able to recognize previously parasitized eggs and the super parasitism reduced the parasitoid.reproductive success. (author)

Inevitability of Genetic Parasites

Science.gov (United States)

Iranzo, Jaime; Puigbò, Pere; Lobkovsky, Alexander E.; Wolf, Yuri I.

2016-01-01

Abstract Almost all cellular life forms are hosts to diverse genetic parasites with various levels of autonomy including plasmids, transposons and viruses. Theoretical modeling of the evolution of primordial replicators indicates that parasites (cheaters) necessarily evolve in such systems and can be kept at bay primarily via compartmentalization. Given the (near) ubiquity, abundance and diversity of genetic parasites, the question becomes pertinent: are such parasites intrinsic to life? At least in prokaryotes, the persistence of parasites is linked to the rate of horizontal gene transfer (HGT). We mathematically derive the threshold value of the minimal transfer rate required for selfish element persistence, depending on the element duplication and loss rates as well as the cost to the host. Estimation of the characteristic gene duplication, loss and transfer rates for transposons, plasmids and virus-related elements in multiple groups of diverse bacteria and archaea indicates that most of these rates are compatible with the long term persistence of parasites. Notably, a small but non-zero rate of HGT is also required for the persistence of non-parasitic genes. We hypothesize that cells cannot tune their horizontal transfer rates to be below the threshold required for parasite persistence without experiencing highly detrimental side-effects. As a lower boundary to the minimum DNA transfer rate that a cell can withstand, we consider the process of genome degradation and mutational meltdown of populations through Muller’s ratchet. A numerical assessment of this hypothesis suggests that microbial populations cannot purge parasites while escaping Muller’s ratchet. Thus, genetic parasites appear to be virtually inevitable in cellular organisms. PMID:27503291

TIMPs of parasitic helminths - a large-scale analysis of high-throughput sequence datasets.

Science.gov (United States)

Cantacessi, Cinzia; Hofmann, Andreas; Pickering, Darren; Navarro, Severine; Mitreva, Makedonka; Loukas, Alex

2013-05-30

Tissue inhibitors of metalloproteases (TIMPs) are a multifunctional family of proteins that orchestrate extracellular matrix turnover, tissue remodelling and other cellular processes. In parasitic helminths, such as hookworms, TIMPs have been proposed to play key roles in the host-parasite interplay, including invasion of and establishment in the vertebrate animal hosts. Currently, knowledge of helminth TIMPs is limited to a small number of studies on canine hookworms, whereas no information is available on the occurrence of TIMPs in other parasitic helminths causing neglected diseases. In the present study, we conducted a large-scale investigation of TIMP proteins of a range of neglected human parasites including the hookworm Necator americanus, the roundworm Ascaris suum, the liver flukes Clonorchis sinensis and Opisthorchis viverrini, as well as the schistosome blood flukes. This entailed mining available transcriptomic and/or genomic sequence datasets for the presence of homologues of known TIMPs, predicting secondary structures of defined protein sequences, systematic phylogenetic analyses and assessment of differential expression of genes encoding putative TIMPs in the developmental stages of A. suum, N. americanus and Schistosoma haematobium which infect the mammalian hosts. A total of 15 protein sequences with high homology to known eukaryotic TIMPs were predicted from the complement of sequence data available for parasitic helminths and subjected to in-depth bioinformatic analyses. Supported by the availability of gene manipulation technologies such as RNA interference and/or transgenesis, this work provides a basis for future functional explorations of helminth TIMPs and, in particular, of their role/s in fundamental biological pathways linked to long-term establishment in the vertebrate hosts, with a view towards the development of novel approaches for the control of neglected helminthiases.

Echinococcosis and other parasitic infections in domestic dogs from urban areas of an Argentinean Patagonian city

Directory of Open Access Journals (Sweden)

Verónica Flores

2017-12-01

Full Text Available In urban populations of South America, dogs with free access to public areas represent a public health concern. The primary consequence of roaming dogs on human health is the transmission of infectious and parasitic diseases mainly through feces contamination. The main diseases likely to be transmitted are hydatidosis or echinococcosis, larva migrans, and giardiasis. In Argentina, hydatidosis ranks among the most prevalent zoonosis. Although it is considered a rural disease, the circulation of this parasite in urban areas has been documented. The aim of this work was to survey intestinal parasites in canine feces from two low-income urban neighborhoods of Bariloche city, Argentina, and to assess their seasonal variation. During 2016, 188 fresh dog feces were collected from sidewalks in 40 randomly selected blocks from the neighborhoods. Each sample was processed by Sheater flotation and tested for a coproantigen (CAg by ELISA. The percentage of parasitized feces was 65.3% (95% CI: 55.9%-73.8%. Eleven parasite species were found, 3 protozoan, 3 cestodes, and 5 nematodes. Echinococcus sp. was present in 9.3% of the samples (95% CI: 4.7%-16.1%. Canine echinococcosis rates resulted similar to rates found previously in other neighborhoods of the city. The life cycle of Echinococcus sp. is sustained in urban areas by the entry of parasitized livestock, domiciliary slaughtering, and inadequate deposition of offal. The risk of Echinococcus sp. transmission to people in these neighborhoods is very high, due to high density of free-roaming dogs and high percentages of infected feces, similar to percentages observed in rural areas.

Parasite specialization in a unique habitat: hummingbirds as reservoirs of generalist blood parasites of Andean birds.

Science.gov (United States)

Moens, Michaël A J; Valkiūnas, Gediminas; Paca, Anahi; Bonaccorso, Elisa; Aguirre, Nikolay; Pérez-Tris, Javier

2016-09-01

Understanding how parasites fill their ecological niches requires information on the processes involved in the colonization and exploitation of unique host species. Switching to hosts with atypical attributes may favour generalists broadening their niches or may promote specialization and parasite diversification as the consequence. We analysed which blood parasites have successfully colonized hummingbirds, and how they have evolved to exploit such a unique habitat. We specifically asked (i) whether the assemblage of Haemoproteus parasites of hummingbirds is the result of single or multiple colonization events, (ii) to what extent these parasites are specialized in hummingbirds or shared with other birds and (iii) how hummingbirds contribute to sustain the populations of these parasites, in terms of both prevalence and infection intensity. We sampled 169 hummingbirds of 19 species along an elevation gradient in Southern Ecuador to analyse the host specificity, diversity and infection intensity of Haemoproteus by molecular and microscopy techniques. In addition, 736 birds of 112 species were analysed to explore whether hummingbird parasites are shared with other birds. Hummingbirds hosted a phylogenetically diverse assemblage of generalist Haemoproteus lineages shared with other host orders. Among these parasites, Haemoproteus witti stood out as the most generalized. Interestingly, we found that infection intensities of this parasite were extremely low in passerines (with no detectable gametocytes), but very high in hummingbirds, with many gametocytes seen. Moreover, infection intensities of H. witti were positively correlated with the prevalence across host species. Our results show that hummingbirds have been colonized by generalist Haemoproteus lineages on multiple occasions. However, one of these generalist parasites (H. witti) seems to be highly dependent on hummingbirds, which arise as the most relevant reservoirs in terms of both prevalence and

Magnetization of High Density Hadronic Fluid

DEFF Research Database (Denmark)

Bohr, Henrik; Providencia, Constanca; da Providencia, João

2012-01-01

In the present paper the magnetization of a high density relativistic fluid of elementary particles is studied. At very high densities, such as may be found in the interior of a neutron star, when the external magnetic field is gradually increased, the energy of the normal phase of the fluid...... in the particle fluid. For nuclear densities above 2 to 3 rho(0), where rho(0) is the equilibrium nuclear density, the resulting magnetic field turns out to be rather huge, of the order of 10(17) Gauss....

Parasite prevalence corresponds to host life history in a diverse assemblage of afrotropical birds and haemosporidian parasites.

Directory of Open Access Journals (Sweden)

Holly L Lutz

Full Text Available Avian host life history traits have been hypothesized to predict rates of infection by haemosporidian parasites. Using molecular techniques, we tested this hypothesis for parasites from three haemosporidian genera (Plasmodium, Haemoproteus, and Leucocytozoon collected from a diverse sampling of birds in northern Malawi. We found that host life history traits were significantly associated with parasitism rates by all three parasite genera. Nest type and nest location predicted infection probability for all three parasite genera, whereas flocking behavior is an important predictor of Plasmodium and Haemoproteus infection and habitat is an important predictor of Leucocytozoon infection. Parasite prevalence was 79.1% across all individuals sampled, higher than that reported for comparable studies from any other region of the world. Parasite diversity was also exceptionally high, with 248 parasite cytochrome b lineages identified from 152 host species. A large proportion of Plasmodium, Haemoproteus, and Leucocytozoon parasite DNA sequences identified in this study represent new, previously undocumented lineages (n = 201; 81% of total identified based on BLAST queries against the avian malaria database, MalAvi.

Human-induced eutrophication maintains high parasite prevalence in breeding threespine stickleback populations.

Science.gov (United States)

Budria, Alexandre; Candolin, Ulrika

2015-04-01

Anthropogenic activities are having profound impacts on species interactions, with further consequences for populations and communities. We investigated the influence that anthropogenic eutrophication has on the prevalence of the parasitic tapeworm Schistocephalus solidus in threespine stickleback Gasterosteus aculeatus populations. We caught stickleback from four areas along the coast of Finland, and within each area from one undisturbed and one eutrophied habitat. We found the prevalence of the parasite to be lower in the eutrophied habitats at the start of the breeding season, probably because of fewer piscivorous birds that transmit the parasite. However, while the prevalence of the parasite declined across the season in the undisturbed habitat, it did less so in eutrophied habitats. We discuss different processes that could be behind the differences, such as lower predation rate on infected fish, higher food availability and less dispersal in eutrophied habitats. We found no effect of eutrophication on the proportion of infected stickleback that entered reproductive condition. Together with earlier findings, this suggests that eutrophication increases the proportion of infected stickleback that reproduce. This could promote the evolution of less parasite resistant populations, with potential consequences for the viability of the interacting parties of the host-parasite system.

Parasitic Infections In A Developing Country: The Vermiform ...

African Journals Online (AJOL)

The vermiform appendix may become a yielding target and an innocent victim of intestinal parasitism. This is likely to occur more readily in those parts of the developing world in which the parasitic load in the community is high. This high parasitic load more commonly afflicts people of low socio-economic class. This report is ...

Food webs and fishing affect parasitism of the sea urchin Eucidaris galapagensis in the Galápagos

Science.gov (United States)

Sonnenholzner, Jorge I.; Lafferty, Kevin D.; Ladah, Lydia B.

2011-01-01

In the Galápagos Islands, two eulimid snails parasitize the common pencil sea urchin, Eucidaris galapagensis. Past work in the Galápagos suggests that fishing reduces lobster and fish densities and, due to this relaxation of predation pressure, indirectly increases urchin densities, creating the potential for complex indirect interactions between fishing and parasitic snails. To measure indirect effects of fishing on these parasitic snails, we investigated the spatial relationships among urchins, parasitic snails, commensal crabs, and large urchin predators (hogfish and lobsters). Parasitic snails had higher densities at sites where urchins were abundant, probably due to increased resource availability. Commensal crabs that shelter under urchin spines, particularly the endemic Mithrax nodosus, preyed on the parasitic snails in aquaria, and snails were less abundant at field sites where these crabs were common. In aquaria, hogfish and lobsters readily ate crabs, but crabs were protected from predation under urchin spines, leading to a facultative mutualism between commensal crabs and urchins. In the field, fishing appeared to indirectly increase the abundance of urchins and their commensal crabs by reducing predation pressure from fish and lobsters. Fished sites had fewer snails per urchin, probably due to increased predation from commensal crabs. However, because fished sites also tended to have more urchins, there was no significant net effect of fishing on the number of snails per square meter. These results suggest that fishing can have complex indirect effects on parasites by altering food webs.

Parasite Removal, but Not Herbivory, Deters Future Parasite Attachment on Tomato

Science.gov (United States)

Tjiurutue, Muvari Connie; Palmer-Young, Evan C.; Adler, Lynn S.

2016-01-01

Plants face many antagonistic interactions that occur sequentially. Often, plants employ defense strategies in response to the initial damage that are highly specific and can affect interactions with subsequent antagonists. In addition to herbivores and pathogens, plants face attacks by parasitic plants, but we know little about how prior herbivory compared to prior parasite attachment affects subsequent host interactions. If host plants can respond adaptively to these different damage types, we predict that prior parasitism would have a greater deterrent effect on subsequent parasites than would prior herbivory. To test the effects of prior parasitism and prior herbivory on subsequent parasitic dodder (Cuscuta spp.) preference, we conducted two separate greenhouse studies with tomato hosts (Solanum lycopersicum). In the first experiment, we tested the effects of previous dodder attachment on subsequent dodder preference on tomato hosts using three treatments: control plants that had no previous dodder attachment; dodder-removed plants that had an initial dodder seedling attached, removed and left in the same pot to simulate parasite death; and dodder-continuous plants with an initial dodder seedling that remained attached. In the second experiment, we tested the effects of previous caterpillar damage (Spodoptera exigua) and mechanical damage on future dodder attachment on tomato hosts. Dodder attached most slowly to tomato hosts that had dodder plants previously attached and then removed, compared to control plants or plants with continuous dodder attachment. In contrast, herbivory did not affect subsequent dodder attachment rate. These results indicate that dodder preference depended on the identity and the outcome of the initial attack, suggesting that early-season interactions have the potential for profound impacts on subsequent community dynamics. PMID:27529694

Parasite Removal, but Not Herbivory, Deters Future Parasite Attachment on Tomato.

Directory of Open Access Journals (Sweden)

Muvari Connie Tjiurutue

Full Text Available Plants face many antagonistic interactions that occur sequentially. Often, plants employ defense strategies in response to the initial damage that are highly specific and can affect interactions with subsequent antagonists. In addition to herbivores and pathogens, plants face attacks by parasitic plants, but we know little about how prior herbivory compared to prior parasite attachment affects subsequent host interactions. If host plants can respond adaptively to these different damage types, we predict that prior parasitism would have a greater deterrent effect on subsequent parasites than would prior herbivory. To test the effects of prior parasitism and prior herbivory on subsequent parasitic dodder (Cuscuta spp. preference, we conducted two separate greenhouse studies with tomato hosts (Solanum lycopersicum. In the first experiment, we tested the effects of previous dodder attachment on subsequent dodder preference on tomato hosts using three treatments: control plants that had no previous dodder attachment; dodder-removed plants that had an initial dodder seedling attached, removed and left in the same pot to simulate parasite death; and dodder-continuous plants with an initial dodder seedling that remained attached. In the second experiment, we tested the effects of previous caterpillar damage (Spodoptera exigua and mechanical damage on future dodder attachment on tomato hosts. Dodder attached most slowly to tomato hosts that had dodder plants previously attached and then removed, compared to control plants or plants with continuous dodder attachment. In contrast, herbivory did not affect subsequent dodder attachment rate. These results indicate that dodder preference depended on the identity and the outcome of the initial attack, suggesting that early-season interactions have the potential for profound impacts on subsequent community dynamics.

Human presence increases parasitic load in endangered lion-tailed macaques (Macaca silenus in its fragmented rainforest habitats in Southern India.

Directory of Open Access Journals (Sweden)

Shaik Hussain

Full Text Available BACKGROUND: Understanding changes in the host-parasite relationship due to habitat fragmentation is necessary for better management and conservation of endangered species in fragmented landscapes. Pathogens and parasites can pose severe threat to species in restricted environments such as forest fragments where there is increased contact of wildlife with human and livestock populations. Environmental stress and reduced nutritional level in forest fragments can influence parasite infection and intensity on the native species. In this study, we examine the impact of habitat fragmentation on the prevalence of gastrointestinal parasites in lion-tailed macaques in a fragmented rainforest in Western Ghats. METHODS: The prevalence of different gastrointestinal parasites was estimated from 91 fecal samples collected from 9 lion-tailed macaque groups in nine forest fragments. The parasites were identified up to genus level on the basis of the morphology and coloration of the egg, larva and cyst. The covariates included forest fragment area, group size and the presence/absence of human settlements and livestock in proximity. We used a linear regression model to identify the covariates that significantly influenced the prevalence of different parasite taxa. RESULTS: Nine gastrointestinal parasite taxa were detected in lion-tailed macaque groups. The groups near human settlements had greater prevalence and number of taxa, and these variables also had significant positive correlations with group size. We found that these parameters were also greater in groups near human settlements after controlling for group size. Livestock were present in all five fragments that had human settlements in proximity. CONCLUSION: The present study suggests that high prevalence and species richness of gastrointestinal parasites in lion-tailed macaque groups are directly related to habitat fragmentation, high anthropogenic activities and high host density. The parasite load

Social Parasites

Science.gov (United States)

Lopez, Miguel A.; Nguyen, HoangKim T.; Oberholzer, Michael; Hill, Kent L.

2011-01-01

Summary of recent advances Protozoan parasites cause tremendous human suffering worldwide, but strategies for therapeutic intervention are limited. Recent studies illustrate that the paradigm of microbes as social organisms can be brought to bear on questions about parasite biology, transmission and pathogenesis. This review discusses recent work demonstrating adaptation of social behaviors by parasitic protozoa that cause African sleeping sickness and malaria. The recognition of social behavior and cell-cell communication as a ubiquitous property of bacteria has transformed our view of microbiology, but protozoan parasites have not generally been considered in this context. Works discussed illustrate the potential for concepts of sociomicrobiology to provide insight into parasite biology and should stimulate new approaches for thinking about parasites and parasite-host interactions. PMID:22020108

Parasite stress promotes homicide and child maltreatment

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Thornhill, Randy; Fincher, Corey L.

2011-01-01

Researchers using the parasite-stress theory of human values have discovered many cross-cultural behavioural patterns that inform a range of scholarly disciplines. Here, we apply the theory to major categories of interpersonal violence, and the empirical findings are supportive. We hypothesize that the collectivism evoked by high parasite stress is a cause of adult-on-adult interpersonal violence. Across the US states, parasite stress and collectivism each positively predicts rates of men's and women's slaying of a romantic partner, as well as the rate of male-honour homicide and of the motivationally similar felony-related homicide. Of these four types of homicide, wealth inequality has an independent effect only on rates of male-honour and felony-related homicide. Parasite stress and collectivism also positively predict cross-national homicide rates. Child maltreatment by caretakers is caused, in part, by divestment in offspring of low phenotypic quality, and high parasite stress produces more such offspring than low parasite stress. Rates of each of two categories of the child maltreatment—lethal and non-lethal—across the US states are predicted positively by parasite stress, with wealth inequality and collectivism having limited effects. Parasite stress may be the strongest predictor of interpersonal violence to date. PMID:22042922

Population collapse to extinction: the catastrophic combination of parasitism and Allee effect.

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Hilker, Frank M

2010-01-01

Infectious diseases are responsible for the extinction of a number of species. In conventional epidemic models, the transition from endemic population persistence to extirpation takes place gradually. However, if host demographics exhibits a strong Allee effect (AE) (population decline at low densities), extinction can occur abruptly in a catastrophic population crash. This might explain why species suddenly disappear even when they used to persist at high endemic population levels. Mathematically, the tipping point towards population collapse is associated with a saddle-node bifurcation. The underlying mechanism is the simultaneous population size depression and the increase of the extinction threshold due to parasite pathogenicity and Allee effect. Since highly pathogenic parasites cause their own extinction but not that of their host, there can be another saddle-node bifurcation with the re-emergence of two endemic equilibria. The implications for control interventions are discussed, suggesting that effective management may be possible for ℛ(0)≫1.

Notification, an Important Neglected Essential Education for Children in Kindergartens and Primary Schools (Education about Parasitic Infections in Kindergartens

Directory of Open Access Journals (Sweden)

Emad Ahmadiara

2017-09-01

Full Text Available One of the most important threats to global public health, especially in developing countries is parasitic infections. These infections are very common in children and young people especially those who kept in kindergarten and primary schools. Because of the high population density and sometimes by the lack of adequate hygiene, these places are prone to parasitic infections. Infestation causes by ectoparasites like pediculosis, water-borne protozoan infections like giardiasis and the last but not less important, helminth infection like as Oxyuris are a permanent threat for children in this places.

Introduction of New Parasites in Denmark

DEFF Research Database (Denmark)

Enemark, Heidi L.

examples of such parasites/parasitic diseases: Setaria tundra, a mosquito-borne filarioid nematode which was detected for the first time in Danish deer in 2010. This parasite is usually considered harmless but is capable of causing peritonitis and mortality in ungulates. The newly detected parasite...... was genetically very similar to previously published isolates from France and Italy, and may have been spread to Denmark from southern Europe. Giardia spp. a zoonotic, unicellular parasite (protozoa) well known in Danish livestock but recently found in extremely high numbers in Danish deer with chronic diarrhea...... for the first time in Denmark approximately 10 years ago in 3 foxes from the Copenhagen area. Since then, no systematic surveillance has been performed, and therefore the current prevalence among wildlife and pets is unknown. So far the parasite has not been found in intermediate hosts (rodents) in Denmark...

Parasites and parasite management practices of organic and conventional dairy herds in Minnesota.

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Sorge, U S; Moon, R D; Stromberg, B E; Schroth, S L; Michels, L; Wolff, L J; Kelton, D F; Heins, B J

2015-05-01

The objective of this study was to describe the prevalence and practices used to manage internal helminth parasites and external arthropod parasites on organic and conventional dairy herds in Minnesota. All organic (ORG) dairy herds in Minnesota (n=114) and a convenience sample of conventional herds were invited to participate in the study. Thirty-five ORG herds and 28 conventional herds were visited once in summer and fall of 2012. Conventional dairy herds were split into small conventional (SC,conventional herds (MC, ≥200 cows) so that SC herds were comparable in size to the ORG herds. Dairy managers were surveyed to assess their farm management practices and perceptions about parasites, hygiene scores were recorded for adult stock, and fecal samples were collected from a nominal 20 breeding-age heifers to characterize abundance of internal parasites. Nonparametric tests were used to compare fecal egg counts per gram (FEC) among farms grouped by management systems and practices. Organic farms had more designated pasture and were more likely to use rotational grazing compared with conventional farms, but the stocking densities of animals on pasture were similar among farm types. The overall FEC were very low, and only a few individual ORG heifers had FEC >500 eggs/gram. Samples from heifers on ORG farms had significantly more strongyle-type eggs than those on SC and MC farms (ORG: 6.6±2.1; SC: 0.5±0.3; MC: 0.8±0.7), but egg counts of other types of gastrointestinal parasites did not differ significantly among the 3 herd groups. Fly control measures were applied mainly to milking cows and preweaned calves and were used on 88.6% of ORG herds, 60.0% of SC herds, and 91.7% of MC herds. Approximately half of the producers reported having seen skin conditions suggestive of lice or tail mange in their cattle during the previous winter (ORG: 48.6%, SC: 57.1%, MC: 53.9%). Although most conventional producers reported treating these skin conditions, most organic

High mortality associated with tapeworm parasitism in geladas (Theropithecus gelada) in the Simien Mountains National Park, Ethiopia.

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Schneider-Crease, India; Griffin, Randi H; Gomery, Megan A; Bergman, Thore J; Beehner, Jacinta C

2017-09-01

Despite increasing appreciation for parasitism as an important component of primate ecology and evolution, surprisingly few studies have demonstrated the costs of helminth parasitism in primates. Detecting parasite-related costs in primates is particularly difficult because it requires detailed, long-term data on individual host reproductive success, survival, and parasitism. The identification of the larval tapeworm Taenia serialis in geladas under intensive long-term study in the Ethiopian Highlands (Nguyen et al. [2015] American Journal of Primatology, 77:579-594; Schneider-Crease et al. [2013] Veterinary Parasitology 198:240-243) provides an opportunity to examine how an endemic parasite impacts host reproductive success and survival. We used survival analyses to assess the mortality risk associated with protuberant larval cysts characteristic of T. serialis using a decade of data from a gelada population in the Simien Mountains National Park (SMNP), Ethiopia. We demonstrated strikingly high mortality associated with T. serialis cysts in adult females, particularly for younger adults. The estimated effect of cysts on male mortality was similar, although the effect was not statistically significant, likely owing to the smaller sample size. Additionally, the offspring of mothers with cysts experienced increased mortality, which was driven almost entirely by maternal death. Mothers with cysts had such high mortality that they rarely completed an interbirth interval. Comparison with a study of this parasite in another gelada population on the Guassa Plateau (Nguyen et al. [2015] American Journal of Primatology, 77:579-594) revealed lower cyst prevalence in the SMNP and similar cyst-associated mortality. However, many more females with cysts completed interbirth intervals at Guassa than in the SMNP, suggesting that T. serialis cysts may kill hosts more rapidly in the SMNP. Our results point toward the underlying causes of individual and population

Microaspiration of esophageal gland cells and cDNA library construction for identifying parasitism genes of plant-parasitic nematodes.

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Hussey, Richard S; Huang, Guozhong; Allen, Rex

2011-01-01

Identifying parasitism genes encoding proteins secreted from a plant-parasitic nematode's esophageal gland cells and injected through its stylet into plant tissue is the key to understanding the molecular basis of nematode parasitism of plants. Parasitism genes have been cloned by directly microaspirating the cytoplasm from the esophageal gland cells of different parasitic stages of cyst or root-knot nematodes to provide mRNA to create a gland cell-specific cDNA library by long-distance reverse-transcriptase polymerase chain reaction. cDNA clones are sequenced and deduced protein sequences with a signal peptide for secretion are identified for high-throughput in situ hybridization to confirm gland-specific expression.

Rapid evolution of parasite life history traits on an expanding range-edge.

Science.gov (United States)

Kelehear, Crystal; Brown, Gregory P; Shine, Richard

2012-04-01

Parasites of invading species undergoing range advance may be exposed to powerful new selective forces. Low host density in range-edge populations hampers parasite transmission, requiring the parasite to survive longer periods in the external environment before encountering a potential host. These conditions should favour evolutionary shifts in offspring size to maximise parasite transmission. We conducted a common-garden experiment to compare life history traits among seven populations of the nematode lungworm (Rhabdias pseudosphaerocephala) spanning from the parasite population core to the expanding range-edge in invasive cane toads (Rhinella marina) in tropical Australia. Compared to conspecifics from the population core, nematodes from the range-edge exhibited larger eggs, larger free-living adults and larger infective larvae, and reduced age at maturity in parasitic adults. These results support a priori predictions regarding adaptive changes in offspring size as a function of invasion history, and suggest that parasite life history traits can evolve rapidly in response to the selective forces exerted by a biological invasion. © 2012 Blackwell Publishing Ltd/CNRS.

A Network Approach to Analyzing Highly Recombinant Malaria Parasite Genes

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Larremore, Daniel B.; Clauset, Aaron; Buckee, Caroline O.

2013-01-01

The var genes of the human malaria parasite Plasmodium falciparum present a challenge to population geneticists due to their extreme diversity, which is generated by high rates of recombination. These genes encode a primary antigen protein called PfEMP1, which is expressed on the surface of infected red blood cells and elicits protective immune responses. Var gene sequences are characterized by pronounced mosaicism, precluding the use of traditional phylogenetic tools that require bifurcating tree-like evolutionary relationships. We present a new method that identifies highly variable regions (HVRs), and then maps each HVR to a complex network in which each sequence is a node and two nodes are linked if they share an exact match of significant length. Here, networks of var genes that recombine freely are expected to have a uniformly random structure, but constraints on recombination will produce network communities that we identify using a stochastic block model. We validate this method on synthetic data, showing that it correctly recovers populations of constrained recombination, before applying it to the Duffy Binding Like-α (DBLα) domain of var genes. We find nine HVRs whose network communities map in distinctive ways to known DBLα classifications and clinical phenotypes. We show that the recombinational constraints of some HVRs are correlated, while others are independent. These findings suggest that this micromodular structuring facilitates independent evolutionary trajectories of neighboring mosaic regions, allowing the parasite to retain protein function while generating enormous sequence diversity. Our approach therefore offers a rigorous method for analyzing evolutionary constraints in var genes, and is also flexible enough to be easily applied more generally to any highly recombinant sequences. PMID:24130474

A network approach to analyzing highly recombinant malaria parasite genes.

Science.gov (United States)

Larremore, Daniel B; Clauset, Aaron; Buckee, Caroline O

2013-01-01

The var genes of the human malaria parasite Plasmodium falciparum present a challenge to population geneticists due to their extreme diversity, which is generated by high rates of recombination. These genes encode a primary antigen protein called PfEMP1, which is expressed on the surface of infected red blood cells and elicits protective immune responses. Var gene sequences are characterized by pronounced mosaicism, precluding the use of traditional phylogenetic tools that require bifurcating tree-like evolutionary relationships. We present a new method that identifies highly variable regions (HVRs), and then maps each HVR to a complex network in which each sequence is a node and two nodes are linked if they share an exact match of significant length. Here, networks of var genes that recombine freely are expected to have a uniformly random structure, but constraints on recombination will produce network communities that we identify using a stochastic block model. We validate this method on synthetic data, showing that it correctly recovers populations of constrained recombination, before applying it to the Duffy Binding Like-α (DBLα) domain of var genes. We find nine HVRs whose network communities map in distinctive ways to known DBLα classifications and clinical phenotypes. We show that the recombinational constraints of some HVRs are correlated, while others are independent. These findings suggest that this micromodular structuring facilitates independent evolutionary trajectories of neighboring mosaic regions, allowing the parasite to retain protein function while generating enormous sequence diversity. Our approach therefore offers a rigorous method for analyzing evolutionary constraints in var genes, and is also flexible enough to be easily applied more generally to any highly recombinant sequences.

A network approach to analyzing highly recombinant malaria parasite genes.

Directory of Open Access Journals (Sweden)

Daniel B Larremore

Full Text Available The var genes of the human malaria parasite Plasmodium falciparum present a challenge to population geneticists due to their extreme diversity, which is generated by high rates of recombination. These genes encode a primary antigen protein called PfEMP1, which is expressed on the surface of infected red blood cells and elicits protective immune responses. Var gene sequences are characterized by pronounced mosaicism, precluding the use of traditional phylogenetic tools that require bifurcating tree-like evolutionary relationships. We present a new method that identifies highly variable regions (HVRs, and then maps each HVR to a complex network in which each sequence is a node and two nodes are linked if they share an exact match of significant length. Here, networks of var genes that recombine freely are expected to have a uniformly random structure, but constraints on recombination will produce network communities that we identify using a stochastic block model. We validate this method on synthetic data, showing that it correctly recovers populations of constrained recombination, before applying it to the Duffy Binding Like-α (DBLα domain of var genes. We find nine HVRs whose network communities map in distinctive ways to known DBLα classifications and clinical phenotypes. We show that the recombinational constraints of some HVRs are correlated, while others are independent. These findings suggest that this micromodular structuring facilitates independent evolutionary trajectories of neighboring mosaic regions, allowing the parasite to retain protein function while generating enormous sequence diversity. Our approach therefore offers a rigorous method for analyzing evolutionary constraints in var genes, and is also flexible enough to be easily applied more generally to any highly recombinant sequences.

Parasite and nutrient enrichment effects on Daphnia interspecific competition

NARCIS (Netherlands)

Decaestecker, Ellen; Verreydt, Dino; De Meester, Luc; Declerck, Steven A.J.

2015-01-01

Increased productivity due to nutrient enrichment is hypothesized to affect density-dependent processes, such as transmission success of horizontally transmitting parasites. Changes in nutrient availability can also modify the stoichiometry and condition of individual hosts, which may affect their

The impact of parasites during range expansion of an invasive gecko.

Science.gov (United States)

Barnett, Louise K; Phillips, Ben L; Heath, Allen C G; Coates, Andrew; Hoskin, Conrad J

2018-02-14

Host-parasite dynamics can play a fundamental role in both the establishment success of invasive species and their impact on native wildlife. The net impact of parasites depends on their capacity to switch effectively between native and invasive hosts. Here we explore host-switching, spatial patterns and simple fitness measures in a slow-expanding invasion: the invasion of Asian house geckos (Hemidactylus frenatus) from urban areas into bushland in Northeast Australia. In bushland close to urban edges, H. frenatus co-occurs with, and at many sites now greatly out-numbers, native geckos. We measured prevalence and intensity of Geckobia mites (introduced with H. frenatus), and Waddycephalus (a native pentastome). We recorded a new invasive mite species, and several new host associations for native mites and geckos, but we found no evidence of mite transmission between native and invasive geckos. In contrast, native Waddycephalus nymphs were commonly present in H. frenatus, demonstrating this parasite's capacity to utilize H. frenatus as a novel host. Prevalence of mites on H. frenatus decreased with distance from the urban edge, suggesting parasite release towards the invasion front; however, we found no evidence that mites affect H. frenatus body condition or lifespan. Waddycephalus was present at low prevalence in bushland sites and, although its presence did not affect host body condition, our data suggest that it may reduce host survival. The high relative density of H. frenatus at our sites, and their capacity to harbour Waddycephalus, suggests that there may be impacts on native geckos and snakes through parasite spillback.

Partitioning the aggregation of parasites on hosts into intrinsic and extrinsic components via an extended Poisson-gamma mixture model.

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Justin M Calabrese

Full Text Available It is well known that parasites are often highly aggregated on their hosts such that relatively few individuals host the large majority of parasites. When the parasites are vectors of infectious disease, a key consequence of this aggregation can be increased disease transmission rates. The cause of this aggregation, however, is much less clear, especially for parasites such as arthropod vectors, which generally spend only a short time on their hosts. Regression-based analyses of ticks on various hosts have focused almost exclusively on identifying the intrinsic host characteristics associated with large burdens, but these efforts have had mixed results; most host traits examined have some small influence, but none are key. An alternative approach, the Poisson-gamma mixture distribution, has often been used to describe aggregated parasite distributions in a range of host/macroparasite systems, but lacks a clear mechanistic basis. Here, we extend this framework by linking it to a general model of parasite accumulation. Then, focusing on blacklegged ticks (Ixodes scapularis on mice (Peromyscus leucopus, we fit the extended model to the best currently available larval tick burden datasets via hierarchical Bayesian methods, and use it to explore the relative contributions of intrinsic and extrinsic factors on observed tick burdens. Our results suggest that simple bad luck-inhabiting a home range with high vector density-may play a much larger role in determining parasite burdens than is currently appreciated.

Density measurements of small amounts of high-density solids by a floatation method

International Nuclear Information System (INIS)

Akabori, Mitsuo; Shiba, Koreyuki

1984-09-01

A floatation method for determining the density of small amounts of high-density solids is described. The use of a float combined with an appropriate floatation liquid allows us to measure the density of high-density substances in small amounts. Using the sample of 0.1 g in weight, the floatation liquid of 3.0 g cm -3 in density and the float of 1.5 g cm -3 in apparent density, the sample densities of 5, 10 and 20 g cm -3 are determined to an accuracy better than +-0.002, +-0.01 and +-0.05 g cm -3 , respectively that correspond to about +-1 x 10 -5 cm 3 in volume. By means of appropriate degassing treatments, the densities of (Th,U)O 2 pellets of --0.1 g in weight and --9.55 g cm -3 in density were determined with an accuracy better than +-0.05 %. (author)

A synoptic overview of golden jackal parasites reveals high diversity of species.

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Gherman, Călin Mircea; Mihalca, Andrei Daniel

2017-09-15

The golden jackal (Canis aureus) is a species under significant and fast geographic expansion. Various parasites are known from golden jackals across their geographic range, and certain groups can be spread during their expansion, increasing the risk of cross-infection with other carnivores or even humans. The current list of the golden jackal parasites includes 194 species and was compiled on the basis of an extensive literature search published from historical times until April 2017, and is shown herein in synoptic tables followed by critical comments of the various findings. This large variety of parasites is related to the extensive geographic range, territorial mobility and a very unselective diet. The vast majority of these parasites are shared with domestic dogs or cats. The zoonotic potential is the most important aspect of species reported in the golden jackal, some of them, such as Echinococcus spp., hookworms, Toxocara spp., or Trichinella spp., having a great public health impact. Our review brings overwhelming evidence on the importance of Canis aureus as a wild reservoir of human and animal parasites.

Research on high energy density plasmas and applications

International Nuclear Information System (INIS)

1999-01-01

Recently, technologies on lasers, accelerators, and pulse power machines have been significantly advanced and input power density covers the intensity range from 10 10 W/cm 2 to higher than 10 20 W/cm 2 . As the results, high pressure gas and solid targets can be heated up to very high temperature to create hot dense plasmas which have never appeared on the earth. The high energy density plasmas opened up new research fields such as inertial confinement fusion, high brightness X-ray radiation sources, interiors of galactic nucleus,supernova, stars and planets, ultra high pressure condensed matter physics, plasma particle accelerator, X-ray laser, and so on. Furthermore, since these fields are intimately connected with various industrial sciences and technologies, the high energy density plasma is now studied in industries, government institutions, and so on. This special issue of the Journal of Plasma Physics and Nuclear Fusion Research reviews the high energy density plasma science for the comprehensive understanding of such new fields. In May, 1998, the review committee for investigating the present status and the future prospects of high energy density plasma science was established in the Japan Society of Plasma Science and Nuclear Fusion Research. We held three committee meetings to discuss present status and critical issues of research items related to high energy density plasmas. This special issue summarizes the understandings of the committee. This special issue consists of four chapters: They are Chapter 1: Physics important in the high energy density plasmas, Chapter 2: Technologies related to the plasma generation; drivers such as lasers, pulse power machines, particle beams and fabrication of various targets, Chapter 3: Plasma diagnostics important in high energy density plasma experiments, Chapter 4: A variety of applications of high energy density plasmas; X-ray radiation, particle acceleration, inertial confinement fusion, laboratory astrophysics

Experimental investigation of alternative transmission functions: Quantitative evidence for the importance of nonlinear transmission dynamics in host-parasite systems.

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Orlofske, Sarah A; Flaxman, Samuel M; Joseph, Maxwell B; Fenton, Andy; Melbourne, Brett A; Johnson, Pieter T J

2018-05-01

Understanding pathogen transmission is crucial for predicting and managing disease. Nonetheless, experimental comparisons of alternative functional forms of transmission remain rare, and those experiments that are conducted are often not designed to test the full range of possible forms. To differentiate among 10 candidate transmission functions, we used a novel experimental design in which we independently varied four factors-duration of exposure, numbers of parasites, numbers of hosts and parasite density-in laboratory infection experiments. We used interactions between amphibian hosts and trematode parasites as a model system and all candidate models incorporated parasite depletion. An additional manipulation involving anaesthesia addressed the effects of host behaviour on transmission form. Across all experiments, nonlinear transmission forms involving either a power law or a negative binomial function were the best-fitting models and consistently outperformed the linear density-dependent and density-independent functions. By testing previously published data for two other host-macroparasite systems, we also found support for the same nonlinear transmission forms. Although manipulations of parasite density are common in transmission studies, the comprehensive set of variables tested in our experiments revealed that variation in density alone was least likely to differentiate among competing transmission functions. Across host-pathogen systems, nonlinear functions may often more accurately represent transmission dynamics and thus provide more realistic predictions for infection. © 2017 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

Prevalence of intestinal parasites infections among Afghan children of primary and junior high schools residing Kashan city, Iran, 2009-2010

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Mansoureh Momen Heravi

2013-06-01

Results: out of the 430 students, 49.7% were male and the rest were female. The prevalence of intestinal parasites was 33.5%. The frequency of pathogenic intestinal parasite was 15.4%. The rate of intestinal parasite infections were: Entamoeba coli 16.5%, Giardia lamblia 8.8%,Blastocystis hominis 7%, Endolimax nana 3.4%, Iodamoeba buchlelli 3.4%, Chilomastix mesnili 1.62%, Entamoeba histolytica/E.dispar 1.2%,Hymenolepis nana 1.8% , and Ascaris lumbricoides0.2%.Entrobius vermicularis was found in 13.5% of the students using scotch tape test.There was a significant statistical association between duration of living in Afghanistan and intestinal parasitic infections.(p≤0.03 Conclusion: According to the results of this study, the prevalence of parasitic infections in the Afghan children was rather high. Examination and treatment of the students, education of the children and their parents and teachers in the field of personal hygine and environmental sanitation are necessary for prevention of parasite transmission.

Linking parasite populations in hosts to parasite populations in space through Taylor's law and the negative binomial distribution.

Science.gov (United States)

Cohen, Joel E; Poulin, Robert; Lagrue, Clément

2017-01-03

The spatial distribution of individuals of any species is a basic concern of ecology. The spatial distribution of parasites matters to control and conservation of parasites that affect human and nonhuman populations. This paper develops a quantitative theory to predict the spatial distribution of parasites based on the distribution of parasites in hosts and the spatial distribution of hosts. Four models are tested against observations of metazoan hosts and their parasites in littoral zones of four lakes in Otago, New Zealand. These models differ in two dichotomous assumptions, constituting a 2 × 2 theoretical design. One assumption specifies whether the variance function of the number of parasites per host individual is described by Taylor's law (TL) or the negative binomial distribution (NBD). The other assumption specifies whether the numbers of parasite individuals within each host in a square meter of habitat are independent or perfectly correlated among host individuals. We find empirically that the variance-mean relationship of the numbers of parasites per square meter is very well described by TL but is not well described by NBD. Two models that posit perfect correlation of the parasite loads of hosts in a square meter of habitat approximate observations much better than two models that posit independence of parasite loads of hosts in a square meter, regardless of whether the variance-mean relationship of parasites per host individual obeys TL or NBD. We infer that high local interhost correlations in parasite load strongly influence the spatial distribution of parasites. Local hotspots could influence control and conservation of parasites.

Toward Low-Cost, High-Energy Density, and High-Power Density Lithium-Ion Batteries

Science.gov (United States)

Li, Jianlin; Du, Zhijia; Ruther, Rose E.; AN, Seong Jin; David, Lamuel Abraham; Hays, Kevin; Wood, Marissa; Phillip, Nathan D.; Sheng, Yangping; Mao, Chengyu; Kalnaus, Sergiy; Daniel, Claus; Wood, David L.

2017-09-01

Reducing cost and increasing energy density are two barriers for widespread application of lithium-ion batteries in electric vehicles. Although the cost of electric vehicle batteries has been reduced by 70% from 2008 to 2015, the current battery pack cost (268/kWh in 2015) is still >2 times what the USABC targets (125/kWh). Even though many advancements in cell chemistry have been realized since the lithium-ion battery was first commercialized in 1991, few major breakthroughs have occurred in the past decade. Therefore, future cost reduction will rely on cell manufacturing and broader market acceptance. This article discusses three major aspects for cost reduction: (1) quality control to minimize scrap rate in cell manufacturing; (2) novel electrode processing and engineering to reduce processing cost and increase energy density and throughputs; and (3) material development and optimization for lithium-ion batteries with high-energy density. Insights on increasing energy and power densities of lithium-ion batteries are also addressed.

Properties of matter at ultra-high densities

International Nuclear Information System (INIS)

Banerjee, B.; Chitre, S.M.

1975-01-01

The recent discovery of pulsars and their subsequent identification with neutron stars has given a great impetus to the study of the behaviour of matter at ultra high densities. The object of these studies is to calculate the equation of state as a function of density. In this paper, the properties of electrically neutral, cold (T=0) matter at unusually high densities has been reviewed. The physics of the equation of state of such matter divides quite naturally in four density ranges. (i) At the very lowest densities the state of minimum energy is a lattice of 56 Fe atoms. This state persists upto 10 7 g/cm 3 . (ii) In the next density region the nuclei at the lattice sites become neutron rich because the high electron Fermi energy makes inverse beta decay possible. (iii) At a density 4.3 x 10 11 the nuclei become so neutron rich that the neutrons start 'dripping' out of the nuclei and form a gas. This density range is characterised by large, neutron-rich nuclei immersed in a neutron gas. (iv) At a density 2.4 x 10 14 g/cm 3 , the nuclei disappear and a fluid of uniform neutron matter with a small percentage of protons and electrons results. The above four density ranges have been discussed in detail as the equation of state is now well established upto the nuclear density 3 x 10 14 g/cm 3 . The problems of extending the equation of state beyond this density are also touched upon. (author)

The path to host extinction can lead to loss of generalist parasites.

Science.gov (United States)

Farrell, Maxwell J; Stephens, Patrick R; Berrang-Ford, Lea; Gittleman, John L; Davies, T Jonathan

2015-07-01

Host extinction can alter disease transmission dynamics, influence parasite extinction and ultimately change the nature of host-parasite systems. While theory predicts that single-host parasites are among the parasite species most susceptible to extinction following declines in their hosts, documented parasite extinctions are rare. Using a comparative approach, we investigate how the richness of single-host and multi-host parasites is influenced by extinction risk among ungulate and carnivore hosts. Host-parasite associations for free-living carnivores (order Carnivora) and terrestrial ungulates (orders Perissodactyla + Cetartiodactyla minus cetaceans) were merged with host trait data and IUCN Red List status to explore the distribution of single-host and multi-host parasites among threatened and non-threatened hosts. We find that threatened ungulates harbour a higher proportion of single-host parasites compared to non-threatened ungulates, which is explained by decreases in the richness of multi-host parasites. However, among carnivores threat status is not a significant predictor of the proportion of single-host parasites, or the richness of single-host or multi-host parasites. The loss of multi-host parasites from threatened ungulates may be explained by decreased cross-species contact as hosts decline and habitats become fragmented. Among carnivores, threat status may not be important in predicting patterns of parasite specificity because host decline results in equal losses of both single-host parasites and multi-host parasites through reduction in average population density and frequency of cross-species contact. Our results contrast with current models of parasite coextinction and highlight the need for updated theories that are applicable across host groups and account for both inter- and intraspecific contact. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

Invasion of parasitic isopods in marine fishes

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Ganapathy Rameshkumar

2013-02-01

Full Text Available Objective: To carry out a detailed three-year observation study on isopod parasites infestation in fish. Methods: Fish samples were collected from different localities in various landing centers along the Tamil Nadu coastal area. The prevalence and mean intensity were calculated. The proximate composition of infestation and uninfestation were studied in different marine fishes. A comparative analysis of bacteria and fungi in the infected and uninfected regions of fishes were analysed. Results: Tweenty six species including 12 genera of isopods (Cymothoidae distributed in 39 species of marine fishes along the Tamil Nadu coast. The isopod parasites were attached in three different microhabitats in host fishes viz. , buccal, branchial and body surfaces. They exhibited host and site specific occurrence. Maximum prevalence 17.11% was recorded in March 2010 and minimum 0.27% in Febuary 2010. The intensity ranged from 1 to 1.7 parasites per fish during the different months from Decmber 2008 to November 2011. There was a decrease in the protein, carbohydrate and lipid content in the infested fishes compared to uninfected fishes. A comparative analysis of bacteria and fungi in the infected and uninfected region of fishes were analysed. It revealed that infected portions had dense bacterial load as observed in the lesions of infected fishes than uninfected fishes. Conclusion: Factors which are able to induce parasitic manifestation are stock quality, stocking density, environmental conditions, biological and physiological characteristics of parasite, zoo technical measures, food quantity, feeding strategies, etc.

High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

International Nuclear Information System (INIS)

Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

2015-01-01

A recent low gas-fill density (0.6 mg/cc 4 He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc 4 He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth

High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

Science.gov (United States)

Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

2015-04-01

A recent low gas-fill density (0.6 mg/cc 4He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc 4He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

Energy Technology Data Exchange (ETDEWEB)

Amendt, Peter; Ho, Darwin D.; Jones, Ogden S. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2015-04-15

A recent low gas-fill density (0.6 mg/cc {sup 4}He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc {sup 4}He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

RNA trafficking in parasitic plant systems

Science.gov (United States)

LeBlanc, Megan; Kim, Gunjune; Westwood, James H.

2012-01-01

RNA trafficking in plants contributes to local and long-distance coordination of plant development and response to the environment. However, investigations of mobile RNA identity and function are hindered by the inherent difficulty of tracing a given molecule of RNA from its cell of origin to its destination. Several methods have been used to address this problem, but all are limited to some extent by constraints associated with accurately sampling phloem sap or detecting trafficked RNA. Certain parasitic plant species form symplastic connections to their hosts and thereby provide an additional system for studying RNA trafficking. The haustorial connections of Cuscuta and Phelipanche species are similar to graft junctions in that they are able to transmit mRNAs, viral RNAs, siRNAs, and proteins from the host plants to the parasite. In contrast to other graft systems, these parasites form connections with host species that span a wide phylogenetic range, such that a high degree of nucleotide sequence divergence may exist between host and parasites and allow confident identification of most host RNAs in the parasite system. The ability to identify host RNAs in parasites, and vice versa, will facilitate genomics approaches to understanding RNA trafficking. This review discusses the nature of host–parasite connections and the potential significance of host RNAs for the parasite. Additional research on host–parasite interactions is needed to interpret results of RNA trafficking studies, but parasitic plants may provide a fascinating new perspective on RNA trafficking. PMID:22936942

RNA trafficking in parasitic plant systems

Directory of Open Access Journals (Sweden)

Megan L LeBlanc

2012-08-01

Full Text Available RNA trafficking in plants contributes to local and long-distance coordination of plant development and response to the environment. However, investigations of mobile RNA identity and function are hindered by the inherent difficulty of tracing a given molecule of RNA from its cell of origin to its destination. Several methods have been used to address this problem, but all are limited to some extent by constraints associated with accurately sampling phloem sap or detecting trafficked RNA. Certain parasitic plant species form symplastic connections to their hosts and thereby provide an additional system for studying RNA trafficking. The haustorial connections of Cuscuta and Phelipanche species are similar to graft junctions in that they are able to transmit mRNAs, viral RNAs, siRNAs and proteins from the host plants to the parasite. In contrast to other graft systems, these parasites form connections with host species that span a wide phylogenetic range, such that a high degree of nucleotide sequence divergence may exist between host and parasites and allow confident identification of most host RNAs in the parasite system. The ability to identify host RNAs in parasites, and vice versa, will facilitate genomics approaches to understanding RNA trafficking. This review discusses the nature of host parasite connections and the potential significance of host RNAs for the parasite. Additional research on host-parasite interactions is needed to interpret results of RNA trafficking studies, but parasitic plants may provide a fascinating new perspective on RNA trafficking.

High frequency of parasitic and viral stool pathogens in patients with active ulcerative colitis: report from a tropical country.

Science.gov (United States)

Banerjee, Debabrata; Deb, Rachana; Dar, Lalit; Mirdha, Bijay R; Pati, Sunil K; Thareja, Sandeep; Falodia, Sushil; Ahuja, Vineet

2009-01-01

Diarrhoeal relapses in patients with ulcerative colitis (UC) may be associated with enteric infections and its diagnosis may lessen avoidable exposure to corticosteroids and/or immunosuppressants. The purpose of this study was to assess the frequency of stool pathogens (parasitic and viral) in patients with active UC. This prospective cross-sectional study included 49 consecutive patients (32 M, 17 F, mean age 35.8+/-12 years) with active UC. Three stool samples were collected from each patient and examined for parasitic infection. Rectal biopsies were obtained during sigmoidoscopy to demonstrate cytomegalovirus (CMV) inclusion bodies and to conduct qualitative polymerase chain reaction (PCR) for CMV and herpes simplex virus (HSV) DNA detection. Median duration of illness was 3.9+/-3.7 years and 83.7% of the patients had moderate to severe disease. The prevalence of parasitic infections in UC was 12%. The organisms isolated were Strongyloides stercoralis in 4%, Ankylostoma duodenale in 4%, Cryptosporidium in 2% and Entamoeba histolytica in 2% of the patients. The prevalence of CMV and HSV in rectal biopsies using qualitative PCR was 8% and 10%, respectively. No predictive factor was identified with CMV superinfection in patients with active UC. In India there is a high prevalence of parasitic and viral infections in patients with active UC. The results of the study suggest that, in tropical countries with a known high prevalence of parasitic diseases, aggressive evaluation for parasitic and viral infections should be carried out, as early identification and prompt treatment of such infections can improve the clinical course of patients with active UC.

Host Diet Affects the Morphology of Monarch Butterfly Parasites.

Science.gov (United States)

Hoang, Kevin; Tao, Leiling; Hunter, Mark D; de Roode, Jacobus C

2017-06-01

Understanding host-parasite interactions is essential for ecological research, wildlife conservation, and health management. While most studies focus on numerical traits of parasite groups, such as changes in parasite load, less focus is placed on the traits of individual parasites such as parasite size and shape (parasite morphology). Parasite morphology has significant effects on parasite fitness such as initial colonization of hosts, avoidance of host immune defenses, and the availability of resources for parasite replication. As such, understanding factors that affect parasite morphology is important in predicting the consequences of host-parasite interactions. Here, we studied how host diet affected the spore morphology of a protozoan parasite ( Ophryocystis elektroscirrha ), a specialist parasite of the monarch butterfly ( Danaus plexippus ). We found that different host plant species (milkweeds; Asclepias spp.) significantly affected parasite spore size. Previous studies have found that cardenolides, secondary chemicals in host plants of monarchs, can reduce parasite loads and increase the lifespan of infected butterflies. Adding to this benefit of high cardenolide milkweeds, we found that infected monarchs reared on milkweeds of higher cardenolide concentrations yielded smaller parasites, a potentially hidden characteristic of cardenolides that may have important implications for monarch-parasite interactions.

The Eurasian beaver (Castor fiber) is apparently not a host to blood parasites in Norway.

Science.gov (United States)

Cross, Hannah B; Campbell-Palmer, Róisín; Girling, Simon; Rosell, Frank

2012-11-23

Parasites can alter the physiology and behaviour of host species and negatively impact on their fitness thus affecting population densities. This is the first investigation into the presence of blood parasites in the Eurasian beaver (Castor fiber); a species that has been the subject of many translocation and reintroduction programmes. Two hundred and seventy blood slides prepared from the blood of 27 beavers from southern Norway were microscopically analysed for the presence of blood parasites. This study reports an absence of blood parasites in the Norwegian Eurasian beavers sampled. Copyright © 2012 Elsevier B.V. All rights reserved.

Photoionization and High Density Gas

Science.gov (United States)

Kallman, T.; Bautista, M.; White, Nicholas E. (Technical Monitor)

2002-01-01

We present results of calculations using the XSTAR version 2 computer code. This code is loosely based on the XSTAR v.1 code which has been available for public use for some time. However it represents an improvement and update in several major respects, including atomic data, code structure, user interface, and improved physical description of ionization/excitation. In particular, it now is applicable to high density situations in which significant excited atomic level populations are likely to occur. We describe the computational techniques and assumptions, and present sample runs with particular emphasis on high density situations.

Gastrointestinal parasites of feral cats from Christmas Island.

Science.gov (United States)

Adams, P J; Elliot, A D; Algar, D; Brazell, R I

2008-01-01

To investigate the gastrointestinal parasites present in feral cats on Christmas Island, with particular interest in the protozoan parasite Toxoplasma gondii. Faecal and serum samples were collected from 28 and 25 cats respectively that were trapped as part of an ongoing eradication program being run on Christmas Island by the Department of Environment and Conservation. Faecal samples were screened microscopically for helminth and protozoan parasites. Serum samples were screened for antibodies to T gondii using a commercial indirect immunofluorescence assay (IFA) and a latex agglutination test (LAT). The most common helminth parasites detected were Toxocara cati (present in 15 of 28 faecal samples), Strongyloides sp (13/28), Aelurostrongylus abstrusus, (7/28), an unidentified capillarid (6/28) and Ancylostoma sp (4/28). Based on serology, T gondii was the most common parasite detected (protozoan or otherwise) with antibodies detected in 24 serum samples by IFA and 23 serum samples by LAT. Cats on Christmas Island harbour many of the helminth and protozoan parasites reported from feral cats elsewhere in Australia. The high seroprevalence of T gondii in these cats indicates a high level of exposure to the parasite in this environment.

Electronic DC transformer with high power density

NARCIS (Netherlands)

Pavlovský, M.

2006-01-01

This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components

Exploring the diversity and distribution of neotropical avian malaria parasites--a molecular survey from Southeast Brazil.

Directory of Open Access Journals (Sweden)

Gustavo A Lacorte

Full Text Available Southeast Brazil is a neotropical region composed of a mosaic of different tropical habitats and mountain chains, which allowed for the formation of bird-rich communities with distinct ecological niches. Although this region has the potential to harbor a remarkable variety of avian parasites, there is a lack of information about the diversity of malarial parasites. We used molecular approaches to characterize the lineage diversity of Plasmodium and Haemoproteus in bird communities from three different habitats in southeast Brazil based on the prevalence, richness and composition of lineages. We observed an overall prevalence of 35.3%, with a local prevalence ranging from 17.2% to 54.8%. Moreover, no significant association between prevalence and habitat type could be verified (p>0.05. We identified 89 Plasmodium and 22 Haemoproteus lineages, with 86% of them described for the first time here, including an unusual infection of a non-columbiform host by a Haemoproteus (Haemoproteus parasite. The composition analyses of the parasite communities showed that the lineage composition from Brazilian savannah and tropical dry forest was similar, but it was different from the lineage composition of Atlantic rainforest, reflecting the greater likeness of the former habitats with respect to seasonality and forest density. No significant effects of habitat type on lineage richness were observed based on GLM analyses. We also found that sites whose samples had a greater diversity of bird species showed a greater diversity of parasite lineages, providing evidence that areas with high bird richness also have high parasite richness. Our findings point to the importance of the neotropical region (southeast Brazil as a major reservoir of new haemosporidian lineages.

Trypanosome lytic factor, an antimicrobial high-density lipoprotein, ameliorates Leishmania infection.

Directory of Open Access Journals (Sweden)

Marie Samanovic

2009-01-01

Full Text Available Innate immunity is the first line of defense against invading microorganisms. Trypanosome Lytic Factor (TLF is a minor sub-fraction of human high-density lipoprotein that provides innate immunity by completely protecting humans from infection by most species of African trypanosomes, which belong to the Kinetoplastida order. Herein, we demonstrate the broader protective effects of human TLF, which inhibits intracellular infection by Leishmania, a kinetoplastid that replicates in phagolysosomes of macrophages. We show that TLF accumulates within the parasitophorous vacuole of macrophages in vitro and reduces the number of Leishmania metacyclic promastigotes, but not amastigotes. We do not detect any activation of the macrophages by TLF in the presence or absence of Leishmania, and therefore propose that TLF directly damages the parasite in the acidic parasitophorous vacuole. To investigate the physiological relevance of this observation, we have reconstituted lytic activity in vivo by generating mice that express the two main protein components of TLFs: human apolipoprotein L-I and haptoglobin-related protein. Both proteins are expressed in mice at levels equivalent to those found in humans and circulate within high-density lipoproteins. We find that TLF mice can ameliorate an infection with Leishmania by significantly reducing the pathogen burden. In contrast, TLF mice were not protected against infection by the kinetoplastid Trypanosoma cruzi, which infects many cell types and transiently passes through a phagolysosome. We conclude that TLF not only determines species specificity for African trypanosomes, but can also ameliorate an infection with Leishmania, while having no effect on T. cruzi. We propose that TLFs are a component of the innate immune system that can limit infections by their ability to selectively damage pathogens in phagolysosomes within the reticuloendothelial system.

Do managed bees drive parasite spread and emergence in wild bees?

Science.gov (United States)

Graystock, Peter; Blane, Edward J; McFrederick, Quinn S; Goulson, Dave; Hughes, William O H

2016-04-01

Bees have been managed and utilised for honey production for centuries and, more recently, pollination services. Since the mid 20th Century, the use and production of managed bees has intensified with hundreds of thousands of hives being moved across countries and around the globe on an annual basis. However, the introduction of unnaturally high densities of bees to areas could have adverse effects. Importation and deployment of managed honey bee and bumblebees may be responsible for parasite introductions or a change in the dynamics of native parasites that ultimately increases disease prevalence in wild bees. Here we review the domestication and deployment of managed bees and explain the evidence for the role of managed bees in causing adverse effects on the health of wild bees. Correlations with the use of managed bees and decreases in wild bee health from territories across the globe are discussed along with suggestions to mitigate further health reductions in wild bees.

Do managed bees drive parasite spread and emergence in wild bees?

Directory of Open Access Journals (Sweden)

Peter Graystock

2016-04-01

Full Text Available Bees have been managed and utilised for honey production for centuries and, more recently, pollination services. Since the mid 20th Century, the use and production of managed bees has intensified with hundreds of thousands of hives being moved across countries and around the globe on an annual basis. However, the introduction of unnaturally high densities of bees to areas could have adverse effects. Importation and deployment of managed honey bee and bumblebees may be responsible for parasite introductions or a change in the dynamics of native parasites that ultimately increases disease prevalence in wild bees. Here we review the domestication and deployment of managed bees and explain the evidence for the role of managed bees in causing adverse effects on the health of wild bees. Correlations with the use of managed bees and decreases in wild bee health from territories across the globe are discussed along with suggestions to mitigate further health reductions in wild bees.

Expression of inducible nitric oxide synthase in macrophages inversely correlates with parasitism of lymphoid tissues in dogs with visceral leishmaniasis.

Science.gov (United States)

Sanches, Françoise P; Tomokane, Thaise Y; Da Matta, Vânia L R; Marcondes, Mary; Corbett, Carlos E P; Laurenti, Márcia D

2014-09-07

There are only a few studies reporting the role of nitric oxide metabolites for controlling macrophage intracellular parasitism, and these are controversial. Therefore, the present study aimed to evaluate the expression of inducible nitric oxide synthase (iNOS) in the lymph nodes and spleen of dogs affected by visceral leishmaniasis through immunohistochemistry and to determine its correlation with tissue parasite burden and serum interferon (IFN)-γ levels. Twenty-eight dogs were selected and assigned to one of two groups, symptomatic (n = 18) and asymptomatic (n = 10), according to clinical status and laboratory evaluation. A negative control group (n = 6) from a non-endemic region for visceral leishmaniasis was included as well. Parasite density (amastigotes/mm2) was similar between clinical groups in the lymph nodes (P = 0.2401) and spleen (P = 0.8869). The density of iNOS⁺ cells was higher in infected dogs compared to controls (P spleen (P = 0.5940) densities between symptomatic and asymptomatic dogs. A positive correlation was found between the number of iNOS⁺ cells in lymph nodes and interferon-γ levels (r = 0.3776; P = 0.0303), and there was a negative correlation between parasites and iNOS⁺ cell densities both in lymph nodes (r = -0.5341; P = 0.0034) and spleen (r = -0.4669; P = 0.0329). The negative correlation observed between tissue parasitism and the expression of iNOS may be a reflection of NO acting on the control of parasites.

Pollen extracts and constituent sugars increase growth of a trypanosomatid parasite of bumble bees

Directory of Open Access Journals (Sweden)

Evan C. Palmer-Young

2017-05-01

Full Text Available Phytochemicals produced by plants, including at flowers, function in protection against plant diseases, and have a long history of use against trypanosomatid infection. Floral nectar and pollen, the sole food sources for many species of insect pollinators, contain phytochemicals that have been shown to reduce trypanosomatid infection in bumble and honey bees when fed as isolated compounds. Nectar and pollen, however, consist of phytochemical mixtures, which can have greater antimicrobial activity than do single compounds. This study tested the hypothesis that pollen extracts would inhibit parasite growth. Extracts of six different pollens were tested for direct inhibitory activity against cell cultures of the bumble bee trypanosomatid gut parasite Crithidia bombi. Surprisingly, pollen extracts increased parasite growth rather than inhibiting it. Pollen extracts contained high concentrations of sugars, mainly the monosaccharides glucose and fructose. Experimental manipulations of growth media showed that supplemental monosaccharides (glucose and fructose increased maximum cell density, while a common floral phytochemical (caffeic acid with inhibitory activity against other trypanosomatids had only weak inhibitory effects on Crithidia bombi. These results indicate that, although pollen is essential for bees and other pollinators, pollen may promote growth of intestinal parasites that are uninhibited by pollen phytochemicals and, as a result, can benefit from the nutrients that pollen provides.

Spontaneous magnetization in high-density quark matter

DEFF Research Database (Denmark)

Tsue, Yasuhiko; da Providência, João; Providência, Constanca

2015-01-01

It is shown that spontaneous magnetization occurs due to the anomalous magnetic moments of quarks in high-density quark matter under the tensor-type four-point interaction. The spin polarized condensate for each flavor of quark appears at high baryon density, which leads to the spontaneous magnet...

High Energy Density Sciences with High Power Lasers at SACLA

Science.gov (United States)

Kodama, Ryosuke

2013-10-01

One of the interesting topics on high energy density sciences with high power lasers is creation of extremely high pressures in material. The pressures of more than 0.1 TPa are the energy density corresponding to the chemical bonding energy, resulting in expectation of dramatic changes in the chemical reactions. At pressures of more than TPa, most of material would be melted on the shock Hugoniot curve. However, if the temperature is less than 1eV or lower than a melting point at pressures of more than TPa, novel solid states of matter must be created through a pressured phase transition. One of the interesting materials must be carbon. At pressures of more than TPa, the diamond structure changes to BC and cubic at more than 3TPa. To create such novel states of matter, several kinds of isentropic-like compression techniques are being developed with high power lasers. To explore the ``Tera-Pascal Science,'' now we have a new tool which is an x-ray free electron laser as well as high power lasers. The XFEL will clear the details of the HED states and also efficiently create hot dense matter. We have started a new project on high energy density sciences using an XFEL (SACLA) in Japan, which is a HERMES (High Energy density Revolution of Matter in Extreme States) project.

The high density and high βpol disruption mechanism on TFTR

International Nuclear Information System (INIS)

Fredrickson, E.D.; Manickam, J.; McGuire, K.M.; Monticello, D.; Nagayama, Y.; Park, W.; Taylor, G.

1992-01-01

Studies of disruptions on TFTR have been extended to include high density disruptions as well as the high β pol disruptions. The data strongly suggests that the (m,n)=(1,1) mode plays an important role in both types of disruptions. Further, for the first time, it is unambiguously shown, using a fast electron cyclotron emission (ECE) instrument for the electron temperature profile measurements, that the (m,n)=(1,1) precursor to the high density disruptions has a 'cold bubble' structure. The precursor to the major disruption at high density resembles the 'vacuum bubble' model of disruptions first proposed by Kadomtsev and Pogutse. (author) 2 refs., 2 figs

Electrode/Dielectric Strip For High-Energy-Density Capacitor

Science.gov (United States)

Yen, Shiao-Ping S.

1994-01-01

Improved unitary electrode/dielectric strip serves as winding in high-energy-density capacitor in pulsed power supply. Offers combination of qualities essential for high energy density: high permittivity of dielectric layers, thinness, and high resistance to breakdown of dielectric at high electric fields. Capacitors with strip material not impregnated with liquid.

Laser fusion and high energy density science

International Nuclear Information System (INIS)

Kodama, Ryosuke

2005-01-01

High-power laser technology is now opening a variety of new fields of science and technology using laser-produced plasmas. The laser plasma is now recognized as one of the important tools for the investigation and application of matter under extreme conditions, which is called high energy density science. This chapter shows a variety of applications of laser-produced plasmas as high energy density science. One of the more attractive industrial and science applications is the generation of intense pulse-radiation sources, such as the generation of electro-magnetic waves in the ranges of EUV (Extreme Ultra Violet) to gamma rays and laser acceleration of charged particles. The laser plasma is used as an energy converter in this regime. The fundamental science applications of high energy density physics are shown by introducing laboratory astrophysics, the equation of state of high pressure matter, including warm dense matter and nuclear science. Other applications are also presented, such as femto-second laser propulsion and light guiding. Finally, a new systematization is proposed to explore the possibility of the high energy density plasma application, which is called high energy plasma photonics''. This is also exploration of the boundary regions between laser technology and beam optics based on plasma physics. (author)

Operation and control of high density tokamak reactors

International Nuclear Information System (INIS)

Attenberger, S.E.; McAlees, D.G.

1976-01-01

The incentive for high density operation of a tokamak reactor was discussed. It is found that high density permits ignition in a relatively small, moderately elongated plasma with a moderate magnetic field strength. Under these conditions, neutron wall loadings approximately 4 MW/m 2 must be tolerated. The sensitivity analysis with respect to impurity effects shows that impurity control will most likely be necessary to achieve the desired plasma conditions. The charge exchange sputtered impurities are found to have an important effect so that maintaining a low neutral density in the plasma is critical. If it is assumed that neutral beams will be used to heat the plasma to ignition, high energy injection is required (approximately 250 keV) when heating is accompished at full density. A scenario is outlined where the ignition temperature is established at low density and then the fueling rate is increased to attain ignition. This approach may permit beams with energies being developed for use in TFTR to be successfully used to heat a high density device of the type described here to ignition

Disease dynamics in a specialized parasite of ant societies.

Directory of Open Access Journals (Sweden)

Sandra B Andersen

Full Text Available Coevolution between ant colonies and their rare specialized parasites are intriguing, because lethal infections of workers may correspond to tolerable chronic diseases of colonies, but the parasite adaptations that allow stable coexistence with ants are virtually unknown. We explore the trade-offs experienced by Ophiocordyceps parasites manipulating ants into dying in nearby graveyards. We used field data from Brazil and Thailand to parameterize and fit a model for the growth rate of graveyards. We show that parasite pressure is much lower than the abundance of ant cadavers suggests and that hyperparasites often castrate Ophiocordyceps. However, once fruiting bodies become sexually mature they appear robust. Such parasite life-history traits are consistent with iteroparity--a reproductive strategy rarely considered in fungi. We discuss how tropical habitats with high biodiversity of hyperparasites and high spore mortality has likely been crucial for the evolution and maintenance of iteroparity in parasites with low dispersal potential.

High density high-TC ceramic superconductors by hot pressing

International Nuclear Information System (INIS)

Mak, S.; Chaklader, A.C.D.

1989-01-01

High density and high T C superconductor specimens, YBa 2 Cu 3 O x , have been produced by hot-pressing. The factors studied are the effect of hot pressing on the density, the oxygen stoichiometry, the crystal structure, and the critical temperature. Hot pressing followed by heat treatment increased the density of the specimen to 93%. The hot pressing itself did not significantly affect the oxygen content in the specimen, and although the crystal structure appeared to be orthorhombic, the specimens were not superconducting above liquid nitrogen temperature. The superconductivity was restored after head treatment in oxygen. The highest critical temperature (T C ) of the hot pressed pellets was 82K, which was slightly lower than the T C that could be obtained with the cold pressed/sintered pellets. (6 refs., 5 figs., tab.)

Characterization of Endotrypanum Parasites Using Specific Monoclonal Antibodies

Directory of Open Access Journals (Sweden)

Ramos Franco Antonia Maria

1997-01-01

Full Text Available A large number of Endotrypanum stocks (representing an heterogeneous population of strains have been screened against a panel of monoclonal antibodies (MAbs derived for selected species of Endotrypanum or Leishmania, to see whether this approach could be used to group/differentiate further among these parasites. Using different immunological assay systems, MAbs considered specific for the genus Endotrypanum (E-24, CXXX-3G5-F12 or strain M6159 of E. schaudinni (E-2, CXIV-3C7-F5 reacted variably according to the test used but in the ELISA or immunofluorescence assay both reacted with all the strains tested. Analyses using these MAbs showed antigenic diversity occurring among the Endotrypanum strains, but no qualitative or quantitative reactivity pattern could be consistently related to parasite origin (i.e., host species involved or geographic area of isolation. Western blot analyses of the parasites showed that these MAbs recognized multiple components. Differences existed either in the epitope density or molecular forms associated with the antigenic determinants and therefore allowed the assignment of the strains to specific antigenic groups. Using immunofluorescence or ELISA assay, clone E-24 produced reaction with L. equatorensis (which is a parasite of sloth and rodent, but not with other trypanosomatids examined. Interestingly, the latter parasite and the Endotrypanum strains cross-reacted with a number of MAbs that were produced against members of the L. major-L. tropica complex

Feedback controlled, reactor relevant, high-density, high-confinement scenarios at ASDEX Upgrade

Science.gov (United States)

Lang, P. T.; Blanken, T. C.; Dunne, M.; McDermott, R. M.; Wolfrum, E.; Bobkov, V.; Felici, F.; Fischer, R.; Janky, F.; Kallenbach, A.; Kardaun, O.; Kudlacek, O.; Mertens, V.; Mlynek, A.; Ploeckl, B.; Stober, J. K.; Treutterer, W.; Zohm, H.; ASDEX Upgrade Team

2018-03-01

One main programme topic at the ASDEX Upgrade all-metal-wall tokamak is development of a high-density regime with central densities at reactor grade level while retaining high-confinement properties. This required development of appropriate control techniques capable of coping with the pellet tool, a powerful means of fuelling but one which presented challenges to the control system for handling of related perturbations. Real-time density profile control was demonstrated, raising the core density well above the Greenwald density while retaining the edge density in order to avoid confinement losses. Recently, a new model-based approach was implemented that allows direct control of the central density. Investigations focussed first on the N-seeding scenario owing to its proven potential to yield confinement enhancements. Combining pellets and N seeding was found to improve the divertor buffering further and enhance the operational range accessible. For core densities up to about the Greenwald density, a clear improvement with respect to the non-seeding reference was achieved; however, at higher densities this benefit is reduced. This behaviour is attributed to recurrence of an outward shift of the edge density profile, resulting in a reduced peeling-ballooning stability. This is similar to the shift seen during strong gas puffing, which is required to prevent impurity influx in ASDEX Upgrade. First tests indicate that highly-shaped plasma configurations like the ITER base-line scenario, respond very well to pellet injection, showing efficient fuelling with no measurable impact on the edge density profile.

High Density Digital Data Storage System

Science.gov (United States)

Wright, Kenneth D., II; Gray, David L.; Rowland, Wayne D.

1991-01-01

The High Density Digital Data Storage System was designed to provide a cost effective means for storing real-time data from the field-deployable digital acoustic measurement system. However, the high density data storage system is a standalone system that could provide a storage solution for many other real time data acquisition applications. The storage system has inputs for up to 20 channels of 16-bit digital data. The high density tape recorders presently being used in the storage system are capable of storing over 5 gigabytes of data at overall transfer rates of 500 kilobytes per second. However, through the use of data compression techniques the system storage capacity and transfer rate can be doubled. Two tape recorders have been incorporated into the storage system to produce a backup tape of data in real-time. An analog output is provided for each data channel as a means of monitoring the data as it is being recorded.

High-density-plasma diagnostics in magnetic-confinement fusion

International Nuclear Information System (INIS)

Jahoda, F.C.

1982-01-01

The lectures will begin by defining high density in the context of magnetic confinement fusion research and listing some alternative reactor concepts, ranging from n/sub e/ approx. 2 x 10 14 cm -3 to several orders of magnitude greater, that offer potential advantages over the main-line, n/sub e/ approx. 1 x 10 14 cm -3 , Tokamak reactor designs. The high density scalings of several major diagnostic techniques, some favorable and some disadvantageous, will be discussed. Special emphasis will be given to interferometric methods, both electronic and photographic, for which integral n/sub e/dl measurements and associated techniques are accessible with low wavelength lasers. Reactor relevant experience from higher density, smaller dimension devices exists. High density implies high β, which implies economies of scale. The specialized features of high β diagnostics will be discussed

From Fossil Parasitoids to Vectors: Insects as Parasites and Hosts.

Science.gov (United States)

Nagler, Christina; Haug, Joachim T

2015-01-01

Within Metazoa, it has been proposed that as many as two-thirds of all species are parasitic. This propensity towards parasitism is also reflected within insects, where several lineages independently evolved a parasitic lifestyle. Parasitic behaviour ranges from parasitic habits in the strict sense, but also includes parasitoid, phoretic or kleptoparasitic behaviour. Numerous insects are also the host for other parasitic insects or metazoans. Insects can also serve as vectors for numerous metazoan, protistan, bacterial and viral diseases. The fossil record can report this behaviour with direct (parasite associated with its host) or indirect evidence (insect with parasitic larva, isolated parasitic insect, pathological changes of host). The high abundance of parasitism in the fossil record of insects can reveal important aspects of parasitic lifestyles in various evolutionary lineages. For a comprehensive view on fossil parasitic insects, we discuss here different aspects, including phylogenetic systematics, functional morphology and a direct comparison of fossil and extant species. Copyright © 2015 Elsevier Ltd. All rights reserved.

Parasites

Centers for Disease Control (CDC) Podcasts

2010-05-06

In this podcast, a listener wants to know what to do if he thinks he has a parasite or parasitic disease.  Created: 5/6/2010 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 5/6/2010.

The maintenance of hybrids by parasitism in a freshwater snail.

Science.gov (United States)

Guttel, Yonathan; Ben-Ami, Frida

2014-11-01

Hybrids have often been labelled evolutionary dead-ends due to their lower fertility and viability. However, there is growing awareness that hybridisation between different species may play a constructive role in animal evolution as a means to create variability. Thus, hybridisation and introgression may contribute to adaptive evolution, for example with regards to natural antagonists (parasites, predators, competitors) and adaptation to local environmental conditions. Here we investigated whether parasite intensity contributes to the continuous recreation of hybrids in 74 natural populations of Melanopsis, a complex of freshwater snails with three species. We also examined, under laboratory conditions, whether hybrids and their parental taxa differ in their tolerance of low and high temperatures and salinity levels. Infections were consistently less prevalent in males than in females, and lower in snails from deeper habitats. Infection prevalence in hybrids was significantly lower than in the parental taxa. Low hybrid infection rates could not be explained by sediment type, snail density or geographic distribution of the sampling sites. Interestingly, infected hybrid snails did not show signs of parasite-induced gigantism, whereas all parental taxa did. We found that hybrids mostly coped with extreme temperatures and salinity levels as well as their parental taxa did. Taken together, our results suggest that Melanopsis hybrids perform better in the presence of parasites and environmental stress. This may explain the widespread and long-term occurrence of Melanopsis hybrids as evidenced by paleontological and biogeographic data. Hybridisation may be an adaptive host strategy, reducing infection rates and resisting gigantism. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Probing topological relations between high-density and low-density regions of 2MASS with hexagon cells

Energy Technology Data Exchange (ETDEWEB)

Wu, Yongfeng [American Physical Society, San Diego, CA (United States); Xiao, Weike, E-mail: yongfeng.wu@maine.edu [Department of Astronautics Engineering, Harbin Institute of Technology, P.O. Box 345, Heilongjiang Province 150001 (China)

2014-02-01

We introduced a new two-dimensional (2D) hexagon technique for probing the topological structure of the universe in which we mapped regions of the sky with high and low galaxy densities onto a 2D lattice of hexagonal unit cells. We defined filled cells as corresponding to high-density regions and empty cells as corresponding to low-density regions. The numbers of filled cells and empty cells were kept the same by controlling the size of the cells. By analyzing the six sides of each hexagon, we could obtain and compare the statistical topological properties of high-density and low-density regions of the universe in order to have a better understanding of the evolution of the universe. We applied this hexagonal method to Two Micron All Sky Survey data and discovered significant topological differences between the high-density and low-density regions. Both regions had significant (>5σ) topological shifts from both the binomial distribution and the random distribution.

Towards high-density matter with relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Nagamiya, Shoji.

1990-04-01

Recent progress in nucleus-nucleus collisions at BNL and CERN suggests a hint that the formation of high-density nuclear matter could be possible with relativistic heavy-ion beams. What is the maximum density that can be achieved by heavy-ion collisions? Are there data which show evidence or hints on the formation of high density matter? Why is the research of high-density interesting? How about the future possibilities on this subject? These points are discussed. (author)

New aspects of high energy density plasma

International Nuclear Information System (INIS)

Hotta, Eiki

2005-10-01

The papers presented at the symposium on 'New aspects of high energy density plasma' held at National Institute for Fusion Science are collected in this proceedings. The papers reflect the present status and recent progress in the experiments and theoretical works on high energy density plasma produced by pulsed power technology. The 13 of the presented papers are indexed individually. (J.P.N.)

Parasites and cancers: parasite antigens as possible targets for cancer immunotherapy.

Science.gov (United States)

Darani, Hossein Yousofi; Yousefi, Morteza

2012-12-01

An adverse relationship between some parasite infections and cancer in the human population has been reported by different research groups. Anticancer activity of some parasites such as Trypanosoma cruzi, Toxoplasma gondii, Toxocara canis, Acantamoeba castellani and Plasmodium yoelii has been shown in experimental animals. Moreover, it has been shown that cancer-associated mucin-type O-glycan compositions are made by parasites, therefore cancers and parasites have common antigens. In this report anticancer activities of some parasites have been reviewed and the possible mechanisms of these actions have also been discussed.

Does moving up a food chain increase aggregation in parasites?

Science.gov (United States)

Lester, R J G; McVinish, R

2016-05-01

General laws in ecological parasitology are scarce. Here, we evaluate data on numbers of fish parasites published by over 200 authors to determine whether acquiring parasites via prey is associated with an increase in parasite aggregation. Parasite species were grouped taxonomically to produce 20 or more data points per group as far as possible. Most parasites that remained at one trophic level were less aggregated than those that had passed up a food chain. We use a stochastic model to show that high parasite aggregation in predators can be solely the result of the accumulation of parasites in their prey. The model is further developed to show that a change in the predators feeding behaviour with age may further increase parasite aggregation. © 2016 The Author(s).

The risk of pathogenic intestinal parasite infections in Kisii Municipality, Kenya

Directory of Open Access Journals (Sweden)

Kabiru Ephantus W

2008-07-01

Full Text Available Abstract Background Intestinal parasitic infections are among the most common infections worldwide. Various epidemiological studies indicate that the prevalence of intestinal parasites is high especially in developing countries, although in many of these, the environmental risk factors have not been clearly elucidated. The objective of this study was to determine the risk of pathogenic intestinal parasites infections in Kisii Municipality. Methods Random sampling was used in the selection of the study samples. Stool parasitological profiles of food handlers were done by direct smear and formalin-ethyl acetate sedimentation method. Both vegetable and meat samples were examined for the presence of intestinal parasites. The storage and meat handling practices of the various butcheries were observed. Results Types of samples examined for occurrence of intestinal parasites includes, a total of 84 vegetable, 440 meat and 168 stool samples. Fifty five (65.5% vegetable, 334 (75.9% meat and 69 (41.1% of the stool samples were found positive for intestinal parasites indicating a high overall risk (66.18% for intestinal parasite infections. Of the parasites detected, the most common parasites infesting the foodstuffs and infecting the food handlers were Ascaris lumbricoides and Entamoeba histolytica. Parasites were significantly less likely to be present on meat that was refrigerated during display than meat that was displayed at ambient temperature. Conclusion There is a high risk of infection with intestinal parasites in the sampled Municipal markets. About half of the food handlers surveyed (41.1 % at the Municipal Hospital had one or more parasitic infections. Furthermore, meat (65.5% and vegetables (75.9% sold at the Municipal market were found to be contaminated with parasites hence the inhabitants requires a need for education on food safety, good distribution practices and improvement on sanitary conditions.

Phenolic acid changes during Orobanche parasitism on faba bean ...

African Journals Online (AJOL)

The present work is intended to provide further information on broomrape parasitism based on phenolic acid changes in either the host plant(s) or in each of the host and the parasite in the host-parasite system. Detection of phenolic acids was carried out using high performance liquid chromatography (HPLC) in the host ...

High current density ion source

International Nuclear Information System (INIS)

King, H.J.

1977-01-01

A high-current-density ion source with high total current is achieved by individually directing the beamlets from an electron bombardment ion source through screen and accelerator electrodes. The openings in these screen and accelerator electrodes are oriented and positioned to direct the individual beamlets substantially toward a focus point. 3 figures, 1 table

Plasma Photonic Devices for High Energy Density Science

International Nuclear Information System (INIS)

Kodama, R.

2005-01-01

High power laser technologies are opening a variety of attractive fields of science and technology using high energy density plasmas such as plasma physics, laboratory astrophysics, material science, nuclear science including medical applications and laser fusion. The critical issues in the applications are attributed to the control of intense light and enormous density of charged particles including efficient generation of the particles such as MeV electrons and protons with a current density of TA/cm2. Now these application possibilities are limited only by the laser technology. These applications have been limited in the control of the high power laser technologies and their optics. However, if we have another device consisted of the 4th material, i.e. plasma, we will obtain a higher energy density condition and explore the application possibilities, which could be called high energy plasma device. One of the most attractive devices has been demonstrated in the fast ignition scheme of the laser fusion, which is cone-guiding of ultra-intense laser light in to high density regions1. This is one of the applications of the plasma device to control the ultra-intense laser light. The other role of the devices consisted of transient plasmas is control of enormous energy-density particles in a fashion analogous to light control with a conventional optical device. A plasma fibre (5?m/1mm), as one example of the devices, has guided and deflected the high-density MeV electrons generated by ultra-intense laser light 2. The electrons have been well collimated with either a lens-like plasma device or a fibre-like plasma, resulting in isochoric heating and creation of ultra-high pressures such as Giga bar with an order of 100J. Plasmas would be uniquely a device to easily control the higher energy density particles like a conventional optical device as well as the ultra-intense laser light, which could be called plasma photonic device. (Author)

Nematode parasites of animals are more prone to develop xenobiotic resistance than nematode parasites of plants

Directory of Open Access Journals (Sweden)

Silvestre A.

2004-06-01

Full Text Available In this paper, we concentrate on a comparison of plant and animal-parasitic nematodes, to gain insight into the factors that influence the acquisition of the drug resistance by nematodes. Comparing nematode parasite of domestic animals and cultivated plants, it appears that drug resistance threatens only domestic animal production. Does the paucity of report on nematicide field resistance reflect reality or, is nematicide resistance bypassed by other management practices, specific to cultivated plants (i.e. agricultural control ? First, it seems that selection pressure by treatments in plants is not as efficient as selection pressure in ruminants. Agronomic practices (i.e. sanitation, early planting, usage of nematodes resistant cultivar and crop rotation are frequently used to control parasitic-plant nematodes. Although the efficiency of such measures is generally moderate to high, integrated approaches are developing successfully in parasitic-plant nematode models. Secondly, the majority of anthelmintic resistance cases recorded in animal-parasitic nematodes concern drug families that are not used in plant-parasitic nematodes control (i.e. benzimidazoles, avermectines and levamisole. Thirdly, particular life traits of parasitic-plant nematodes (low to moderate fecundity and reproductive strategy are expected to reduce probability of appearance and transmission of drug resistance genes. It has been demonstrated that, for a large number of nematodes such as Meloidogyne spp., the mode of reproduction by mitotic parthenogenesis reduced genetic diversity of populations which may prevent a rapid drug resistance development. In conclusion, anthelmintic resistance develops in nematode parasite of animals as a consequence of an efficient selection pressure. Early detection of anthelmintic resistance is then crucial : it is not possible to avoid it, but only to delay its development in farm animal industry.

Effective and specific in planta RNAi in cyst nematodes: expression interference of four parasitism genes reduces parasitic success.

Science.gov (United States)

Sindhu, Anoop S; Maier, Tom R; Mitchum, Melissa G; Hussey, Richard S; Davis, Eric L; Baum, Thomas J

2009-01-01

Cyst nematodes are highly evolved sedentary plant endoparasites that use parasitism proteins injected through the stylet into host tissues to successfully parasitize plants. These secretory proteins likely are essential for parasitism as they are involved in a variety of parasitic events leading to the establishment of specialized feeding cells required by the nematode to obtain nourishment. With the advent of RNA interference (RNAi) technology and the demonstration of host-induced gene silencing in parasites, a new strategy to control pests and pathogens has become available, particularly in root-knot nematodes. Plant host-induced silencing of cyst nematode genes so far has had only limited success but similarly should disrupt the parasitic cycle and render the host plant resistant. Additional in planta RNAi data for cyst nematodes are being provided by targeting four parasitism genes through host-induced RNAi gene silencing in transgenic Arabidopsis thaliana, which is a host for the sugar beet cyst nematode Heterodera schachtii. Here it is reported that mRNA abundances of targeted nematode genes were specifically reduced in nematodes feeding on plants expressing corresponding RNAi constructs. Furthermore, this host-induced RNAi of all four nematode parasitism genes led to a reduction in the number of mature nematode females. Although no complete resistance was observed, the reduction of developing females ranged from 23% to 64% in different RNAi lines. These observations demonstrate the relevance of the targeted parasitism genes during the nematode life cycle and, potentially more importantly, suggest that a viable level of resistance in crop plants may be accomplished in the future using this technology against cyst nematodes.

Models for Experimental High Density Housing

Science.gov (United States)

Bradecki, Tomasz; Swoboda, Julia; Nowak, Katarzyna; Dziechciarz, Klaudia

2017-10-01

The article presents the effects of research on models of high density housing. The authors present urban projects for experimental high density housing estates. The design was based on research performed on 38 examples of similar housing in Poland that have been built after 2003. Some of the case studies show extreme density and that inspired the researchers to test individual virtual solutions that would answer the question: How far can we push the limits? The experimental housing projects show strengths and weaknesses of design driven only by such indexes as FAR (floor attenuation ratio - housing density) and DPH (dwellings per hectare). Although such projects are implemented, the authors believe that there are reasons for limits since high index values may be in contradiction to the optimum character of housing environment. Virtual models on virtual plots presented by the authors were oriented toward maximising the DPH index and DAI (dwellings area index) which is very often the main driver for developers. The authors also raise the question of sustainability of such solutions. The research was carried out in the URBAN model research group (Gliwice, Poland) that consists of academic researchers and architecture students. The models reflect architectural and urban regulations that are valid in Poland. Conclusions might be helpful for urban planners, urban designers, developers, architects and architecture students.

Parasites in the Wadden Sea food web

NARCIS (Netherlands)

Thieltges, D.W.; Engelsma, M.Y.; Wendling, C.C.; Wegner, K.M.

2013-01-01

While the free-living fauna of the Wadden Sea has received much interest, little is known on the distribution and effects of parasites in the Wadden Sea food web. However, recent studies on this special type of trophic interaction indicate a high diversity of parasites in the Wadden Sea and suggest

Laboratory Diagnosis of Parasites from the Gastrointestinal Tract.

Science.gov (United States)

Garcia, Lynne S; Arrowood, Michael; Kokoskin, Evelyne; Paltridge, Graeme P; Pillai, Dylan R; Procop, Gary W; Ryan, Norbert; Shimizu, Robyn Y; Visvesvara, Govinda

2018-01-01

This Practical Guidance for Clinical Microbiology document on the laboratory diagnosis of parasites from the gastrointestinal tract provides practical information for the recovery and identification of relevant human parasites. The document is based on a comprehensive literature review and expert consensus on relevant diagnostic methods. However, it does not include didactic information on human parasite life cycles, organism morphology, clinical disease, pathogenesis, treatment, or epidemiology and prevention. As greater emphasis is placed on neglected tropical diseases, it becomes highly probable that patients with gastrointestinal parasitic infections will become more widely recognized in areas where parasites are endemic and not endemic. Generally, these methods are nonautomated and require extensive bench experience for accurate performance and interpretation. Copyright © 2017 American Society for Microbiology.

Parasites and steroid hormones: corticosteroid and sex steroid synthesis, their role in the parasite physiology and development.

Directory of Open Access Journals (Sweden)

Marta C. Romano

2015-06-01

Full Text Available In many cases parasites display highly complex life cycles that include establishment of the larva or adults within host organs, but even in those that have only one host reciprocal intricate interactions occur. A bulk of evidence indicates that steroid hormones influence the development and course of parasitic infections, the host gender susceptibility to the infection and the associate differences in immunological response are good examples of the host-parasite interplay. However, the capacity of these organisms to synthesize their own steroidogenic hormones still has more questions than answers. It is now well known that many parasites synthesize ecdysteroids, but limited information is available on sex steroid and corticosteroid synthesis. This review intends to summarize some of the existing information in the field. In many but not all parasitosis the host hormonal environment determines the susceptibility, the course and severity of parasite infections. In most cases the infection disturbs the host environment, and activate immune responses that finally affect the endocrine system. Furthermore, sex steroids and corticosteroids may also directly modify the parasite reproduction and molting. Available information indicates that parasites synthesize some steroid hormones like ecdysteroids and sex steroids and the presence and activity of related enzymes have been demonstrated. More recently, the synthesis of corticosteroid like compounds has been shown in Taenia solium and tapeworms and in Taenia crassiceps WFU cysticerci. Deeper knowledge of the endocrine properties of parasites will contribute to understand their reproduction and reciprocal interactions with the host, and also may contribute to design tools to combat the infection in some clinical situations.

High density operation in pulsator

International Nuclear Information System (INIS)

Klueber, O.; Cannici, B.; Engelhardt, W.; Gernhardt, J.; Glock, E.; Karger, F.; Lisitano, G.; Mayer, H.M.; Meisel, D.; Morandi, P.

1976-03-01

This report summarizes the results of experiments at high electron densities (>10 14 cm -3 ) which have been achieved by pulsed gas inflow during the discharge. At these densities a regime is established which is characterized by βsub(p) > 1, nsub(i) approximately nsub(e), Tsub(i) approximately Tsub(e) and tausub(E) proportional to nsub(e). Thus the toroidal magnetic field contributes considerably to the plasma confinement and the ions constitute almost half of the plasma pressure. Furthermore, the confinement is appreciably improved and the plasma becomes impermeable to hot neutrals. (orig.) [de

Parasite transmission in a natural multihost–multiparasite community

Science.gov (United States)

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

Parasite transmission in a natural multihost-multiparasite community.

Science.gov (United States)

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).

Flexible asymmetric supercapacitors with high energy and high power density in aqueous electrolytes

Science.gov (United States)

Cheng, Yingwen; Zhang, Hongbo; Lu, Songtao; Varanasi, Chakrapani V.; Liu, Jie

2013-01-01

Supercapacitors with both high energy and high power densities are critical for many practical applications. In this paper, we discuss the design and demonstrate the fabrication of flexible asymmetric supercapacitors based on nanocomposite electrodes of MnO2, activated carbon, carbon nanotubes and graphene. The combined unique properties of each of these components enable highly flexible and mechanically strong films that can serve as electrodes directly without using any current collectors or binders. Using these flexible electrodes and a roll-up approach, asymmetric supercapacitors with 2 V working voltage were successfully fabricated. The fabricated device showed excellent rate capability, with 78% of the original capacitance retained when the scan rate was increased from 2 mV s-1 to 500 mV s-1. Owing to the unique composite structure, these supercapacitors were able to deliver high energy density (24 W h kg-1) under high power density (7.8 kW kg-1) conditions. These features could enable supercapacitor based energy storage systems to be very attractive for a variety of critical applications, such as the power sources in hybrid electric vehicles and the back-up powers for wind and solar energy, where both high energy density and high power density are required.Supercapacitors with both high energy and high power densities are critical for many practical applications. In this paper, we discuss the design and demonstrate the fabrication of flexible asymmetric supercapacitors based on nanocomposite electrodes of MnO2, activated carbon, carbon nanotubes and graphene. The combined unique properties of each of these components enable highly flexible and mechanically strong films that can serve as electrodes directly without using any current collectors or binders. Using these flexible electrodes and a roll-up approach, asymmetric supercapacitors with 2 V working voltage were successfully fabricated. The fabricated device showed excellent rate capability, with 78% of

Fishing drives declines in fish parasite diversity and has variable effects on parasite abundance.

Science.gov (United States)

Wood, Chelsea L; Sandin, Stuart A; Zgliczynski, Brian; Guerra, Ana Sofía; Micheli, Fiorenza

2014-07-01

Despite the ubiquity and ecological importance of parasites, relatively few studies have assessed their response to anthropogenic environmental change. Heuristic models have predicted both increases and decreases in parasite abundance in response to human disturbance, with empirical support for both. However, most studies focus on one or a few selected parasite species. Here, we assess the abundance of parasites of seven species of coral reef fishes collected from three fished and three unfished islands of the Line Islands archipelago in the central equatorial Pacific. Because we chose fish hosts that spanned different trophic levels, taxonomic groups, and body sizes, we were able to compare parasite responses across a broad cross section of the total parasite community in the presence and absence of fishing, a major human impact on marine ecosystems. We found that overall parasite species richness was substantially depressed on fished islands, but that the response of parasite abundance varied among parasite taxa: directly transmitted parasites were significantly more abundant on fished than on unfished islands, while the reverse was true for trophically transmitted parasites. This probably arises because trophically transmitted parasites require multiple host species, some of which are the top predators most sensitive to fishing impacts. The increase in directly transmitted parasites appeared to be due to fishing-driven compensatory increases in the abundance of their hosts. Together, these results provide support for the predictions of both heuristic models, and indicate that the direction of fishing's impact on parasite abundance is mediated by parasite traits, notably parasite transmission strategies.

Some recent efforts toward high density implosions

International Nuclear Information System (INIS)

McClellan, G.E.

1980-01-01

Some recent Livermore efforts towards achieving high-density implosions are presented. The implosion dynamics necessary to compress DT fuel to 10 to 100 times liquid density are discussed. Methods of diagnosing the maximum DT density for a specific design are presented along with results to date. The dynamics of the double-shelled target with an exploding outer shell are described, and some preliminary experimental results are presented

Improved GAMMA 10 tandem mirror confinement in high density plasma

International Nuclear Information System (INIS)

Yatsu, K.; Cho, T.; Higaki, H.; Hirata, M.; Hojo, H.; Ichimura, M.; Ishii, K.; Ishimoto, Y.; Itakura, A.; Katanuma, I.; Kohagura, J.; Minami, R.; Nakashima, Y.; Numakura, T.; Saito, T.; Saosaki, S.; Takemura, Y.; Tatematsu, Y.; Yoshida, M.; Yoshikawa, M.

2003-01-01

GAMMA 10 experiments have advanced in high density experiments after the last IAEA fusion energy conference in 2000 where we reported the production of the high density plasma through use of ion cyclotron range of frequency heating at a high harmonic frequency and neutral beam injection in the anchor cells. However, the diamagnetic signal of the plasma decreased when electron cyclotron resonance heating was applied for the potential formation. Recently a high density plasma has been obtained without degradation of the diamagnetic signal and with much improved reproducibility than before. The high density plasma was attained through adjustment of the spacing of the conducting plates installed in the anchor transition regions. The potential confinement of the plasma has been extensively studied. Dependences of the ion confinement time, ion-energy confinement time and plasma confining potential on plasma density were obtained for the first time in the high density region up to a density of 4x10 18 m -3 . (author)

Immunological investments reflect parasite abundance in island populations of Darwin's finches.

OpenAIRE

Lindström, Karin M.; Foufopoulos, Johannes; Pärn, Henrik; Wikelski, Martin

2004-01-01

The evolution of parasite resistance can be influenced by the abundance of parasites in the environment. However, it is yet unresolved whether vertebrates change their investment in immune function in response to variation in parasite abundance. Here, we compare parasite abundance in four populations of small ground finches (Geospiza fuliginosa) in the Galapagos archipelago. We predicted that populations exposed to high parasite loads should invest more in immune defence, or alternatively use...

The ecology of fish parasites with particular reference to helminth parasites and their salmonid fish hosts in Welsh rivers: a review of some of the central questions.

Science.gov (United States)

Thomas, J D

2002-01-01

Ecological studies carried out in Welsh rivers on the feeding behaviour of salmonid fish, their helminth parasites and intermediate hosts in the early 1950s and in 1998 have been used as a basis to review the literature dealing with the following questions. First, how are the helminth populations dispersed in space-time? Second, to what extent are the distributional patterns and the life history strategies of the parasites influenced by physicochemical factors? Third, to what extent are populations of helmith parasites in salmonid fish influenced by host characteristics including the genome, sex, age, size, social position and Feeding behaviour? Fourth, are the populations of parasites regulated in a density-dependent manner? Fifth, do the parasites influence the survival and wellbeing of their salmonid hosts and the evolution of sex? Sixth, to what extent is the parasite community influenced by environmental changes including those of an anthropogenic nature and can the parasites be used as bioindicators of pollution? As with most parasites the helminth species found were highly overdispersed thus making it necessary to undertake a log10 (1 + x) conversion for statistical analyses. Statistical analyses confirm that the genome, age and sex of salmonid fish hosts, the station and seasonal change in radiation levels were significant factors in predicting the number of parasites. The evidence given supports the hypothesis that the feeding behaviour and habitat selection by the host fish, their position in the social hierarchy and the overdispersed nature of the transmission sites are the key factors in causing differences in the parasitic fauna related to host species, age, size and sex. Differences in the helminth parasite community related to station can be explained on the basis of differences in water types, sediments and chemistry. Although the evidence presented is in accord with the consensus view that temperature is correlated with seasonal changes in the

High-density limit of quantum chromodynamics

International Nuclear Information System (INIS)

Alvarez, E.

1983-01-01

By means of a formal expansion of the partition function presumably valid at large baryon densities, the propagator of the quarks is expressed in terms of the gluon propagator. This result is interpreted as implying that correlations between quarks and gluons are unimportant at high enough density, so that a kind of mean-field approximation gives a very accurate description of the physical system

An annotated list of fish parasites (Isopoda, Copepoda, Monogenea, Digenea, Cestoda, Nematoda) collected from Snappers and Bream (Lutjanidae, Nemipteridae, Caesionidae) in New Caledonia confirms high parasite biodiversity on coral reef fish

OpenAIRE

Justine, Jean-Lou; Beveridge, Ian; Boxshall, Geoffrey A; Bray, Rodney A; Miller, Terrence L; Moravec, František; Trilles, Jean-Paul; Whittington, Ian D

2012-01-01

Background Coral reefs are areas of maximum biodiversity, but the parasites of coral reef fishes, and especially their species richness, are not well known. Over an 8-year period, parasites were collected from 24 species of Lutjanidae, Nemipteridae and Caesionidae off New Caledonia, South Pacific. Results Host-parasite and parasite-host lists are provided, with a total of 207 host-parasite combinations and 58 parasite species identified at the species level, with 27 new host records. Results ...

Fueling with edge recycling to high-density in DIII-D

Energy Technology Data Exchange (ETDEWEB)

Leonard, A.W., E-mail: leonard@fusion.gat.com [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Elder, J.D. [University of Toronto Institute of Aerospace Studies, Toronto, Canada M3H 5T6 (Canada); Canik, J.M. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Groebner, R.J.; Osborne, T.H. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States)

2013-07-15

Pedestal fueling through edge recycling is examined with the interpretive OEDGE code for high-density discharges in DIII-D. A high current, high-density discharge is found to have a similar radial ion flux profile through the pedestal to a lower current, lower density discharge. The higher density discharge, however, has a greater density gradient indicating a pedestal particle diffusion coefficient that scales near linear with 1/I{sub p}. The time dependence of density profile is taken into account in the analysis of a discharge with low frequency ELMs. The time-dependent analysis indicates that the inferred neutral ionization source is inadequate to account for the increase in the density profile between ELMs, implying an inward density convection, or density pinch, near the top of the pedestal.

Monkeys in the middle: parasite transmission through the social network of a wild primate.

Directory of Open Access Journals (Sweden)

Andrew J J MacIntosh

Full Text Available In wildlife populations, group-living is thought to increase the probability of parasite transmission because contact rates increase at high host densities. Physical contact, such as social grooming, is an important component of group structure, but it can also increase the risk of exposure to infection for individuals because it provides a mechanism for transmission of potentially pathogenic organisms. Living in groups can also create variation in susceptibility to infection among individuals because circulating levels of immunosuppressive hormones like glucocorticoids often depend on an individual's position within the group's social structure. Yet, little is known about the relative roles of socially mediated exposure versus susceptibility in parasite transmission among free-living animal groups. To address this issue, we investigate the relationship between host dominance hierarchy and nematode parasite transmission among females in a wild group of Japanese macaques (Macaca fuscata yakui. We use social network analysis to describe each individual female's position within the grooming network in relation to dominance rank and relative levels of infection. Our results suggest that the number of directly-transmitted parasite species infecting each female, and the relative amount of transmission stages that one of these species sheds in faeces, both increase with dominance rank. Female centrality within the network, which shows positive associations with dominance hierarchy, is also positively associated with infection by certain parasite species, suggesting that the measured rank-bias in transmission may reflect variation in exposure rather than susceptibility. This is supported by the lack of a clear relationship between rank and faecal cortisol, as an indicator of stress, in a subset of these females. Thus, socially mediated exposure appears to be important for direct transmission of nematode parasites, lending support to the idea that a

Monkeys in the Middle: Parasite Transmission through the Social Network of a Wild Primate

Science.gov (United States)

MacIntosh, Andrew J. J.; Jacobs, Armand; Garcia, Cécile; Shimizu, Keiko; Mouri, Keiko; Huffman, Michael A.; Hernandez, Alexander D.

2012-01-01

In wildlife populations, group-living is thought to increase the probability of parasite transmission because contact rates increase at high host densities. Physical contact, such as social grooming, is an important component of group structure, but it can also increase the risk of exposure to infection for individuals because it provides a mechanism for transmission of potentially pathogenic organisms. Living in groups can also create variation in susceptibility to infection among individuals because circulating levels of immunosuppressive hormones like glucocorticoids often depend on an individual’s position within the group’s social structure. Yet, little is known about the relative roles of socially mediated exposure versus susceptibility in parasite transmission among free-living animal groups. To address this issue, we investigate the relationship between host dominance hierarchy and nematode parasite transmission among females in a wild group of Japanese macaques (Macaca fuscata yakui). We use social network analysis to describe each individual female’s position within the grooming network in relation to dominance rank and relative levels of infection. Our results suggest that the number of directly-transmitted parasite species infecting each female, and the relative amount of transmission stages that one of these species sheds in faeces, both increase with dominance rank. Female centrality within the network, which shows positive associations with dominance hierarchy, is also positively associated with infection by certain parasite species, suggesting that the measured rank-bias in transmission may reflect variation in exposure rather than susceptibility. This is supported by the lack of a clear relationship between rank and faecal cortisol, as an indicator of stress, in a subset of these females. Thus, socially mediated exposure appears to be important for direct transmission of nematode parasites, lending support to the idea that a classical fitness

Parasites in the Wadden Sea food web

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Thieltges, David W.; Engelsma, Marc Y.; Wendling, Carolin C.; Wegner, K. Mathias

2013-09-01

While the free-living fauna of the Wadden Sea has received much interest, little is known on the distribution and effects of parasites in the Wadden Sea food web. However, recent studies on this special type of trophic interaction indicate a high diversity of parasites in the Wadden Sea and suggest a multitude of effects on the hosts. This also includes effects on specific predator-prey relationships and the general structure of the food web. Focussing on molluscs, a major group in the Wadden Sea in terms of biomass and abundance and an important link between primary producers and predators, we review existing studies and exemplify the ecological role of parasites in the Wadden Sea food web. First, we give a brief inventory of parasites occurring in the Wadden Sea, ranging from microparasites (e.g. protozoa, bacteria) to macroparasites (e.g. helminths, parasitic copepods) and discuss the effects of spatial scale on heterogeneities in infection levels. We then demonstrate how parasites can affect host population dynamics by acting as a strong mortality factor, causing mollusc mass mortalities. In addition, we will exemplify how parasites can mediate the interaction strength of predator-prey relationships and affect the topological structure of the Wadden Sea food web as a whole. Finally, we highlight some ongoing changes regarding parasitism in the Wadden Sea in the course of global change (e.g. species introduction, climate change) and identify important future research questions to entangle the role of parasites in the Wadden Sea food web.

Prevalence of parasites in soil samples in Tehran public places ...

African Journals Online (AJOL)

Results of our findings provide evidence that soil may play an important role in transmission of zoonotic parasite diseases to human. In addition, control of high population of animals such as stray dogs and cats is necessary to reduce the distribution of parasites. Key words: Prevalence, parasites, flotation method, Tehran.

Low density, variation in sintered density and high nitrogen in uranium dioxide

International Nuclear Information System (INIS)

Balakrishna, Palanki; Murty, B.N.; Anuradha, M.; Nageshwara Rao, P.; Jayaraj, R.N.; Ganguly, C.

2000-01-01

Low sintered density and density variation in sintered UO 2 were found to have been caused by non uniformity in the granule feed characteristics to the compacting press. The nitrogen impurity content of sintered UO 2 was found to be sintering furnace related and associated with low sintered density pellets. The problems of low density, variation in sintered density and high nitrogen could be solved by the replacement of the prevailing four punch precompaction by a single punch process; by the introduction of a vibro-sieve for the separation of fine particles from the press feed granules; by innovation in the powder feed shoe design for simultaneous and uniform dispensing of powder in all the die holes; by increasing the final compaction pressure and by modifying the gas flows and preheat temperature in the sintering furnace. (author)

High prevalence of diarrhoegenic intestinal parasite infections among non-ART HIV patients in Fitche Hospital, Ethiopia.

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Adamu, Haileeyesus; Wegayehu, Teklu; Petros, Beyene

2013-01-01

HIV infection has been modifying both the epidemiology and outcome of parasite infections. Hence, this study was undertaken to determine the prevalence of Cryptosporidium and other intestinal parasite infections among HIV positives with and without Antiretroviral Treatment(ART) and its association with CD4+ T-cell count. A cross-sectional study was conducted at Fitche hospital focusing on HIV positives who came to hospital for follow-ups. A total of 378 HIV positive persons with and without ART participated in the study. Data on socio-demographic factors and diarrhoea status were obtained by interviewing all 214 with ART and 164 without ART. Stool samples were collected from all patients and examined for intestinal parasites using direct, formol-ether and modified acid-fast staining techniques. The prevalence of intestinal parasite infections in this study was significantly higher among HIV positive persons not on ART. Specifically, the rate of infection with Cryptosporidium species, Blastocystis spp., Giardia lamblia, and Entamoeba histolytica/E. dispar were higher, particularly in those with CD4+ T-cell counts less than 200 cells/µL. Fifty seven percent of the study participants were on ART. Out of these 164/378 (43%) of the non-ART study participants were infected with at least one intestinal parasite species. Significant association was observed between lower CD4+ T-cell count (parasites were significantly more prevalent in HIV positive non-ART patients. HIV infection increased the risk of having Cryptosporidium and other intestinal parasites and diarrhoea. Therefore, raising HIV positive's immune status and screening for intestinal parasites is important. This study showed that patients who are taking ART had a lower prevalence of diarrhoea causing parasites and Cryptosporidium suggesting that ART through improvement of immune status of the patients may have contributed to controlling diarrhoea-causing parasites in HIV positive patients.

The fish parasite Ichthyophthirius multifiliis

DEFF Research Database (Denmark)

Jørgensen, Louise von Gersdorff

2017-01-01

Ichthyophthirius multifiliis, the causative agent of white spot disease (ichthyophthiriasis) is a major burden for fish farmers and aquarists globally. The parasite infects the skin and the gills of freshwater fish, which may acquire a protective adaptive immune response against this disease...... and recognition of carcinogenic and environmentally damaging effects the most efficient compounds are prohibited. A continuous search for novel substances, which are highly effective against the parasites and harmless for the fish is ongoing. These compounds should be environmentally friendly and cost...

[Concordance between the zinc sulphate flotation and centrifugal sedimentation methods for the diagnosis of intestinal parasites].

Science.gov (United States)

Inês, Elizabete De Jesus; Pacheco, Flavia Thamiris Figueiredo; Pinto, Milena Carneiro; Mendes, Patrícia Silva de Almeida; Da Costa-Ribeiro, Hugo; Soares, Neci Matos; Teixeira, Márcia Cristina Aquino

2016-12-01

The diagnosis of intestinal parasitic infections depends on the parasite load, the specific gravity density of the parasite eggs, oocysts or cysts, and the density and viscosity of flotation or sedimentation medium where faeces are processed. To evaluate the concordance between zinc sulphate flotation and centrifugal sedimentation in the recovery of parasites in faecal samples of children. Faecal samples of 330 children from day care centers were evaluated by zinc sulphate flotation and centrifugal sedimentation techniques. The frequencies of detection of parasites by each method were determined and the agreement between the diagnostic techniques was evaluated using the kappa index, with 95% confidence intervals. The faecal flotation in zinc sulphate diagnosed significantly more cases of Trichuris trichiura infection when compared to centrifugal sedimentation (39/330; 11.8% vs. 13/330; 3.9%, p<0.001), with low diagnostic concordance between methods (kappa=0.264; 95% CI: 0.102-0.427). Moreover, all positive samples for Enterobius vermicularis eggs (n=5) and Strongyloides stercoralis larvae (n=3) were diagnosed only by zinc sulphate. No statistical differences were observed between methods for protozoa identification. The results showed that centrifugal flotation in zinc sulphate solution was significantly more likely to detect light helminths eggs such as those of T. trichiura and E. vermicularis in faeces than the centrifugal sedimentation process.

Characterizing Ancylostoma caninum transcriptome and exploring nematode parasitic adaptation

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Hawdon John

2010-05-01

Full Text Available Abstract Background Hookworm infection is one of the most important neglected diseases in developing countries, with approximately 1 billion people infected worldwide. To better understand hookworm biology and nematode parasitism, the present study generated a near complete transcriptome of the canine hookworm Ancylostoma caninum to a very high coverage using high throughput technology, and compared it to those of the free-living nematode Caenorhabditis elegans and the parasite Brugia malayi. Results The generated transcripts from four developmental stages, infective L3, serum stimulated L3, adult male and adult female, covered 93% of the A. caninum transcriptome. The broad diversity among nematode transcriptomes was confirmed, and an impact of parasitic adaptation on transcriptome diversity was inferred. Intra-population analysis showed that A. caninum has higher coding sequence diversity than humans. Examining the developmental expression profiles of A. caninum revealed major transitions in gene expression from larval stages to adult. Adult males expressed the highest number of selectively expressed genes, but adult female expressed the highest number of selective parasitism-related genes. Genes related to parasitism adaptation and A. caninum specific genes exhibited more expression selectivity while those conserved in nematodes tend to be consistently expressed. Parasitism related genes were expressed more selectively in adult male and female worms. The comprehensive analysis of digital expression profiles along with transcriptome comparisons enabled identification of a set of parasitism genes encoding secretory proteins in animal parasitic nematode. Conclusions This study validated the usage of deep sequencing for gene expression profiling. Parasitic adaptation of the canine hookworm is related to its diversity and developmental dynamics. This comprehensive comparative genomic and expression study substantially improves our understanding of

Parasites and competitors suppress bacterial pathogen synergistically due to evolutionary trade-offs

NARCIS (Netherlands)

Wang, Xiaofang; Wei, Zhong; Li, Mei; Wang, Xueqi; Shan, Anqi; Mei, Xinlan; Jousset, Alexandre; Shen, Qirong; Xu, Yangchun; Friman, Ville Petri

2017-01-01

Parasites and competitors are important for regulating pathogen densities and subsequent disease dynamics. It is, however, unclear to what extent this is driven by ecological and evolutionary processes. Here, we used experimental evolution to study the eco-evolutionary feedbacks among Ralstonia

Parasites as prey

NARCIS (Netherlands)

Goedknegt, M.A.; Welsh, J.E.; Thieltges, D.W.

2012-01-01

Parasites are usually considered to use their hosts as a resource for energy. However, there is increasing awareness that parasites can also become a resource themselves and serve as prey for other organisms. Here we describe various types of predation in which parasites act as prey for other

Spread of a new parasitic B chromosome variant is facilitated by high gene flow.

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María Inmaculada Manrique-Poyato

Full Text Available The B24 chromosome variant emerged several decades ago in a Spanish population of the grasshopper Eyprepocnemis plorans and is currently reaching adjacent populations. Here we report, for the first time, how a parasitic B chromosome (a strictly vertically transmitted parasite expands its geographical range aided by high gene flow in the host species. For six years we analyzed B frequency in several populations to the east and west of the original population and found extensive spatial variation, but only a slight temporal trend. The highest B24 frequency was found in its original population (Torrox and it decreased closer to both the eastern and the western populations. The analysis of Inter Simple Sequence Repeat (ISSR markers showed the existence of a low but significant degree of population subdivision, as well as significant isolation by distance (IBD. Pairwise Nem estimates suggested the existence of high gene flow between the four populations located in the Torrox area, with higher values towards the east. No significant barriers to gene flow were found among these four populations, and we conclude that high gene flow is facilitating B24 diffusion both eastward and westward, with minor role for B24 drive due to the arrival of drive suppressor genes which are also frequent in the donor population.

The neurotropic parasite Toxoplasma gondii increases dopamine metabolism.

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Emese Prandovszky

Full Text Available The highly prevalent parasite Toxoplasma gondii manipulates its host's behavior. In infected rodents, the behavioral changes increase the likelihood that the parasite will be transmitted back to its definitive cat host, an essential step in completion of the parasite's life cycle. The mechanism(s responsible for behavioral changes in the host is unknown but two lines of published evidence suggest that the parasite alters neurotransmitter signal transduction: the disruption of the parasite-induced behavioral changes with medications used to treat psychiatric disease (specifically dopamine antagonists and identification of a tyrosine hydroxylase encoded in the parasite genome. In this study, infection of mammalian dopaminergic cells with T. gondii enhanced the levels of K+-induced release of dopamine several-fold, with a direct correlation between the number of infected cells and the quantity of dopamine released. Immunostaining brain sections of infected mice with dopamine antibody showed intense staining of encysted parasites. Based on these analyses, T. gondii orchestrates a significant increase in dopamine metabolism in neural cells. Tyrosine hydroxylase, the rate-limiting enzyme for dopamine synthesis, was also found in intracellular tissue cysts in brain tissue with antibodies specific for the parasite-encoded tyrosine hydroxylase. These observations provide a mechanism for parasite-induced behavioral changes. The observed effects on dopamine metabolism could also be relevant in interpreting reports of psychobehavioral changes in toxoplasmosis-infected humans.

High throughput nonparametric probability density estimation.

Science.gov (United States)

Farmer, Jenny; Jacobs, Donald

2018-01-01

In high throughput applications, such as those found in bioinformatics and finance, it is important to determine accurate probability distribution functions despite only minimal information about data characteristics, and without using human subjectivity. Such an automated process for univariate data is implemented to achieve this goal by merging the maximum entropy method with single order statistics and maximum likelihood. The only required properties of the random variables are that they are continuous and that they are, or can be approximated as, independent and identically distributed. A quasi-log-likelihood function based on single order statistics for sampled uniform random data is used to empirically construct a sample size invariant universal scoring function. Then a probability density estimate is determined by iteratively improving trial cumulative distribution functions, where better estimates are quantified by the scoring function that identifies atypical fluctuations. This criterion resists under and over fitting data as an alternative to employing the Bayesian or Akaike information criterion. Multiple estimates for the probability density reflect uncertainties due to statistical fluctuations in random samples. Scaled quantile residual plots are also introduced as an effective diagnostic to visualize the quality of the estimated probability densities. Benchmark tests show that estimates for the probability density function (PDF) converge to the true PDF as sample size increases on particularly difficult test probability densities that include cases with discontinuities, multi-resolution scales, heavy tails, and singularities. These results indicate the method has general applicability for high throughput statistical inference.

Not all are free-living: high-throughput DNA metabarcoding reveals a diverse community of protists parasitizing soil metazoa.

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Geisen, S; Laros, I; Vizcaíno, A; Bonkowski, M; de Groot, G A

2015-09-01

Protists, the most diverse eukaryotes, are largely considered to be free-living bacterivores, but vast numbers of taxa are known to parasitize plants or animals. High-throughput sequencing (HTS) approaches now commonly replace cultivation-based approaches in studying soil protists, but insights into common biases associated with this method are limited to aquatic taxa and samples. We created a mock community of common free-living soil protists (amoebae, flagellates, ciliates), extracted DNA and amplified it in the presence of metazoan DNA using 454 HTS. We aimed at evaluating whether HTS quantitatively reveals true relative abundances of soil protists and at investigating whether the expected protist community structure is altered by the co-amplification of metazoan-associated protist taxa. Indeed, HTS revealed fundamentally different protist communities from those expected. Ciliate sequences were highly over-represented, while those of most amoebae and flagellates were under-represented or totally absent. These results underpin the biases introduced by HTS that prevent reliable quantitative estimations of free-living protist communities. Furthermore, we detected a wide range of nonadded protist taxa probably introduced along with metazoan DNA, which altered the protist community structure. Among those, 20 taxa most closely resembled parasitic, often pathogenic taxa. Therewith, we provide the first HTS data in support of classical observational studies that showed that potential protist parasites are hosted by soil metazoa. Taken together, profound differences in amplification success between protist taxa and an inevitable co-extraction of protist taxa parasitizing soil metazoa obscure the true diversity of free-living soil protist communities. © 2015 John Wiley & Sons Ltd.

Parasites: Water

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... Consultations, and General Public. Contact Us Parasites Home Water Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir Parasites can live in natural water sources. When outdoors, treat your water before drinking ...

Host social behavior and parasitic infection: A multifactorial approach

Science.gov (United States)

Ezenwa, V.O.

2004-01-01

I examined associations between several components of host social organization, including group size and gregariousness, group stability, territoriality and social class, and gastrointestinal parasite load in African bovids. At an intraspecific level, group size was positively correlated with parasite prevalence, but only when the parasite was relatively host specific and only among host species living in stable groups. Social class was also an important predictor of infection rates. Among gazelles, territorial males had higher parasite intensities than did either bachelor males or females and juveniles, suggesting that highly territorial individuals may be either more exposed or more susceptible to parasites. Associations among territoriality, grouping, and parasitism were also found across taxa. Territorial host genera were more likely to be infected with strongyle nematodes than were nonterritorial hosts, and gregarious hosts were more infected than were solitary hosts. Analyses also revealed that gregariousness and territoriality had an interactive effect on individual parasite richness, whereby hosts with both traits harbored significantly more parasite groups than did hosts with only one or neither trait. Overall, study results indicate that multiple features of host social behavior influence infection risk and suggest that synergism between traits also has important effects on host parasite load.

Parasitic excitation of ion Bernstein waves from a Faraday shielded fast wave loop antenna

International Nuclear Information System (INIS)

Skiff, F.; Ono, M.; Colestock, P.; Wong, K.L.

1984-12-01

Parasitic excitation of ion Bernstein waves is observed from a Faraday shielded fast wave loop antenna in the ion cyclotron frequency range. Local analysis of the Vlasov-Maxwell equations demonstrates the role of plasma density gradient in the coupling process. The effects of plasma density and of parallel wave number on the excitation process are investigated

Modeling of parasitic elements in high voltage multiplier modules

NARCIS (Netherlands)

Wang, J.

2014-01-01

It is an inevitable trend that the power conversion module will have higher switching frequency and smaller volume in the future. Bandgap devices, such as SiC and GaN devices, accelerate the process. With this process, the parasitic elements in the module will probably have stronger influence on

Highly efficient red electrophosphorescent devices at high current densities

International Nuclear Information System (INIS)

Wu Youzhi; Zhu Wenqing; Zheng Xinyou; Sun, Runguang; Jiang Xueyin; Zhang Zhilin; Xu Shaohong

2007-01-01

Efficiency decrease at high current densities in red electrophosphorescent devices is drastically restrained compared with that from conventional electrophosphorescent devices by using bis(2-methyl-8-quinolinato)4-phenylphenolate aluminum (BAlq) as a hole and exciton blocker. Ir complex, bis(2-(2'-benzo[4,5-α]thienyl) pyridinato-N,C 3' ) iridium (acetyl-acetonate) is used as an emitter, maximum external quantum efficiency (QE) of 7.0% and luminance of 10000cd/m 2 are obtained. The QE is still as high as 4.1% at higher current density J=100mA/cm 2 . CIE-1931 co-ordinates are 0.672, 0.321. A carrier trapping mechanism is revealed to dominate in the process of electroluminescence

The origin of malarial parasites in orangutans.

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M Andreína Pacheco

Full Text Available BACKGROUND: Recent findings of Plasmodium in African apes have changed our perspectives on the evolution of malarial parasites in hominids. However, phylogenetic analyses of primate malarias are still missing information from Southeast Asian apes. In this study, we report molecular data for a malaria parasite lineage found in orangutans. METHODOLOGY/PRINCIPAL FINDINGS: We screened twenty-four blood samples from Pongo pygmaeus (Kalimantan, Indonesia for Plasmodium parasites by PCR. For all the malaria positive orangutan samples, parasite mitochondrial genomes (mtDNA and two antigens: merozoite surface protein 1 42 kDa (MSP-1(42 and circumsporozoite protein gene (CSP were amplified, cloned, and sequenced. Fifteen orangutans tested positive and yielded 5 distinct mitochondrial haplotypes not previously found. The haplotypes detected exhibited low genetic divergence among them, indicating that they belong to one species. We report phylogenetic analyses using mitochondrial genomes, MSP-1(42 and CSP. We found that the orangutan malaria parasite lineage was part of a monophyletic group that includes all the known non-human primate malaria parasites found in Southeast Asia; specifically, it shares a recent common ancestor with P. inui (a macaque parasite and P. hylobati (a gibbon parasite suggesting that this lineage originated as a result of a host switch. The genetic diversity of MSP-1(42 in orangutans seems to be under negative selection. This result is similar to previous findings in non-human primate malarias closely related to P. vivax. As has been previously observed in the other Plasmodium species found in non-human primates, the CSP shows high polymorphism in the number of repeats. However, it has clearly distinctive motifs from those previously found in other malarial parasites. CONCLUSION: The evidence available from Asian apes indicates that these parasites originated independently from those found in Africa, likely as the result of host

The unusual lipid binding proteins of parasitic helminths and their potential roles in parasitism and as therapeutic targets.

Science.gov (United States)

Franchini, Gisela R; Pórfido, Jorge L; Ibáñez Shimabukuro, Marina; Rey Burusco, María F; Bélgamo, Julián A; Smith, Brian O; Kennedy, Malcolm W; Córsico, Betina

2015-02-01

In this review paper we aim at presenting the current knowledge on structural aspects of soluble lipid binding proteins (LBPs) found in parasitic helminths and to discuss their potential role as novel drug targets. Helminth parasites produce and secrete a great variety of LBPs that may participate in the acquisition of nutrients from their host, such as fatty acids and cholesterol. It is also postulated that LBPs might interfere in the regulation of the host׳s immune response by sequestering lipidic intermediates or delivering bioactive lipids. A detailed comprehension of the structure of these proteins, as well as their interactions with ligands and membranes, is important to understand host-parasite relationships that they may mediate. This information could also contribute to determining the role that these proteins may play in the biology of parasitic helminths and how they modulate the immune systems of their hosts, and also towards the development of new therapeutics and prevention of the diseases caused by these highly pathogenic parasites. Copyright © 2014 Elsevier Ltd. All rights reserved.

An annotated list of fish parasites (Isopoda, Copepoda, Monogenea, Digenea, Cestoda, Nematoda) collected from Snappers and Bream (Lutjanidae, Nemipteridae, Caesionidae) in New Caledonia confirms high parasite biodiversity on coral reef fish.

Science.gov (United States)

Justine, Jean-Lou; Beveridge, Ian; Boxshall, Geoffrey A; Bray, Rodney A; Miller, Terrence L; Moravec, František; Trilles, Jean-Paul; Whittington, Ian D

2012-09-04

Coral reefs are areas of maximum biodiversity, but the parasites of coral reef fishes, and especially their species richness, are not well known. Over an 8-year period, parasites were collected from 24 species of Lutjanidae, Nemipteridae and Caesionidae off New Caledonia, South Pacific. Host-parasite and parasite-host lists are provided, with a total of 207 host-parasite combinations and 58 parasite species identified at the species level, with 27 new host records. Results are presented for isopods, copepods, monogeneans, digeneans, cestodes and nematodes. When results are restricted to well-sampled reef fish species (sample size > 30), the number of host-parasite combinations is 20-25 per fish species, and the number of parasites identified at the species level is 9-13 per fish species. Lutjanids include reef-associated fish and deeper sea fish from the outer slopes of the coral reef: fish from both milieus were compared. Surprisingly, parasite biodiversity was higher in deeper sea fish than in reef fish (host-parasite combinations: 12.50 vs 10.13, number of species per fish 3.75 vs 3.00); however, we identified four biases which diminish the validity of this comparison. Finally, these results and previously published results allow us to propose a generalization of parasite biodiversity for four major families of reef-associated fishes (Lutjanidae, Nemipteridae, Serranidae and Lethrinidae): well-sampled fish have a mean of 20 host-parasite combinations per fish species, and the number of parasites identified at the species level is 10 per fish species. Since all precautions have been taken to minimize taxon numbers, it is safe to affirm than the number of fish parasites is at least ten times the number of fish species in coral reefs, for species of similar size or larger than the species in the four families studied; this is a major improvement to our estimate of biodiversity in coral reefs. Our results suggest that extinction of a coral reef fish species

Fundamental properties of high-quality carbon nanofoam: from low to high density

Directory of Open Access Journals (Sweden)

Natalie Frese

2016-12-01

Full Text Available Highly uniform samples of carbon nanofoam from hydrothermal sucrose carbonization were studied by helium ion microscopy (HIM, X-ray photoelectron spectroscopy (XPS, and Raman spectroscopy. Foams with different densities were produced by changing the process temperature in the autoclave reactor. This work illustrates how the geometrical structure, electron core levels, and the vibrational signatures change when the density of the foams is varied. We find that the low-density foams have very uniform structure consisting of micropearls with ≈2–3 μm average diameter. Higher density foams contain larger-sized micropearls (≈6–9 μm diameter which often coalesced to form nonspherical μm-sized units. Both, low- and high-density foams are comprised of predominantly sp2-type carbon. The higher density foams, however, show an advanced graphitization degree and a stronger sp3-type electronic contribution, related to the inclusion of sp3 connections in their surface network.

Sputtered thin films for high density tape recording

NARCIS (Netherlands)

Nguyen, L.T.

This thesis describes the investigation of sputtered thin film media for high density tape recording. As discussed in Chapter 1, to meet the tremendous demand of data storage, the density of recording tape has to be increased continuously. For further increasing the bit density the key factors are:

Investigating the evolution of apoptosis in malaria parasites: the importance of ecology

Directory of Open Access Journals (Sweden)

Pollitt Laura C

2010-11-01

Full Text Available Abstract Apoptosis is a precisely regulated process of cell death which occurs widely in multicellular organisms and is essential for normal development and immune defences. In recent years, interest has grown in the occurrence of apoptosis in unicellular organisms. In particular, as apoptosis has been reported in a wide range of species, including protozoan malaria parasites and trypanosomes, it may provide a novel target for intervention. However, it is important to understand when and why parasites employ an apoptosis strategy before the likely long- and short-term success of such an intervention can be evaluated. The occurrence of apoptosis in unicellular parasites provides a challenge for evolutionary theory to explain as organisms are expected to have evolved to maximise their own proliferation, not death. One possible explanation is that protozoan parasites undergo apoptosis in order to gain a group benefit from controlling their density as this prevents premature vector mortality. However, experimental manipulations to examine the ultimate causes behind apoptosis in parasites are lacking. In this review, we focus on malaria parasites to outline how an evolutionary framework can help make predictions about the ecological circumstances under which apoptosis could evolve. We then highlight the ecological considerations that should be taken into account when designing evolutionary experiments involving markers of cell death, and we call for collaboration between researchers in different fields to identify and develop appropriate markers in reference to parasite ecology and to resolve debates on terminology.

High-density housing that works for all

Energy Technology Data Exchange (ETDEWEB)

Hasan, Arif

2010-03-15

In an urbanising world, the way people fit into cities is vastly important - socially, economically, environmentally, even psychologically. So density, or the number of people living in a given area, is central to urban design and planning. Both governments and markets tend to get density wrong, leading to overcrowding, urban sprawl or often both. A case in point are the high-rise buildings springing up throughtout urban Asia - perceived as key features of that widely touted concept, the 'world-class city'. While some may offer a viable solution to land pressures and density requirements, many built to house evicted or resettled 'slum' dwellers are a social and economic nightmare - inconveniently sited, overcrowded and costly. New evidence from Karachi, Pakistan, reveals a real alternative. Poor people can create liveable high-density settlements as long as community control, the right technical assistance and flexible designs are in place. A city is surely 'world-class' only when it is cosmopolitan – built to serve all, including the poorest.

High density high performance plasma with internal diffusion barrier in Large Helical Device

International Nuclear Information System (INIS)

Sakamoto, R.; Kobayashi, M.; Miyazawa, J.

2008-10-01

A attractive high density plasma operational regime, namely an internal diffusion barrier (IDB), has been discovered in the intrinsic helical divertor configuration on the Large Helical Device (LHD). The IDB which enables core plasma to access a high density/high pressure regime has been developed. It is revealed that the IDB is reproducibly formed by pellet fueling in the magnetic configurations shifted outward in major radius. Attainable central plasma density exceeds 1x10 21 m -3 . Central pressure reaches 1.5 times atmospheric pressure and the central β value becomes fairly high even at high magnetic field, i.e. β(0)=5.5% at B t =2.57 T. (author)

High density data recording for SSCL linac

International Nuclear Information System (INIS)

VanDeusen, A.L.; Crist, C.

1993-01-01

The Superconducting Super Collider Laboratory and AlliedSignal Aerospace have collaboratively developed a high density data monitoring system for beam diagnostic activities. The 128 channel data system is based on a custom multi-channel high speed digitizer card for the VXI bus. The card is referred to as a Modular Input VXI (MIX) digitizer. Multiple MIX cards are used in the complete system to achieve the necessary high channel density requirements. Each MIX digitizer card also contains programmable signal conditioning, and enough local memory to complete an entire beam scan without assistance from the host processor

Parasites of skipjack, Katsuwonus pelamis, from Madeira, Eastern Atlantic.

Science.gov (United States)

Hermida, Margarida; Cavaleiro, Bárbara; Gouveia, Lídia; Saraiva, Aurélia

2018-04-01

Skipjack tuna, Katsuwonus pelamis, is a tropical species of economic importance for fisheries around the world. It occurs seasonally in subtropical waters around Madeira archipelago, in the warmer months. In this study, a parasitological analysis was carried out on a sample of 30 skipjack caught near Madeira Island. A total of 24 parasite taxa were found in this sample. The skipjack parasite community detected was characterized by a wide diversity of parasites, with a predominance of adult didymozoid trematodes, and high prevalences of Tentacularia coryphaenae cestode larvae and Anisakis sp. larvae. Microhabitat distribution of gill parasites was assessed for the most prevalent species, and correlations between parasite abundance and various host features such as size, condition, and fat content were investigated. Parasite taxa which might be useful as biological tags in future studies of skipjack migrations in the Eastern Atlantic were selected.

Amplicon-Based Pyrosequencing Reveals High Diversity of Protistan Parasites in Ships' Ballast Water: Implications for Biogeography and Infectious Diseases.

Science.gov (United States)

Pagenkopp Lohan, K M; Fleischer, R C; Carney, K J; Holzer, K K; Ruiz, G M

2016-04-01

Ships' ballast water (BW) commonly moves macroorganisms and microorganisms across the world's oceans and along coasts; however, the majority of these microbial transfers have gone undetected. We applied high-throughput sequencing methods to identify microbial eukaryotes, specifically emphasizing the protistan parasites, in ships' BW collected from vessels calling to the Chesapeake Bay (Virginia and Maryland, USA) from European and Eastern Canadian ports. We utilized tagged-amplicon 454 pyrosequencing with two general primer sets, amplifying either the V4 or V9 domain of the small subunit (SSU) of the ribosomal RNA (rRNA) gene complex, from total DNA extracted from water samples collected from the ballast tanks of bulk cargo vessels. We detected a diverse group of protistan taxa, with some known to contain important parasites in marine systems, including Apicomplexa (unidentified apicomplexans, unidentified gregarines, Cryptosporidium spp.), Dinophyta (Blastodinium spp., Euduboscquella sp., unidentified syndinids, Karlodinium spp., Syndinium spp.), Perkinsea (Parvilucifera sp.), Opisthokonta (Ichthyosporea sp., Pseudoperkinsidae, unidentified ichthyosporeans), and Stramenopiles (Labyrinthulomycetes). Further characterization of groups with parasitic taxa, consisting of phylogenetic analyses for four taxa (Cryptosporidium spp., Parvilucifera spp., Labyrinthulomycetes, and Ichthyosporea), revealed that sequences were obtained from both known and novel lineages. This study demonstrates that high-throughput sequencing is a viable and sensitive method for detecting parasitic protists when present and transported in the ballast water of ships. These data also underscore the potential importance of human-aided dispersal in the biogeography of these microbes and emerging diseases in the world's oceans.

Characterization of the high density plasma etching process of CCTO thin films for the fabrication of very high density capacitors

International Nuclear Information System (INIS)

Altamore, C; Tringali, C; Sparta', N; Marco, S Di; Grasso, A; Ravesi, S

2010-01-01

In this work the feasibility of CCTO (Calcium Copper Titanate) patterning by etching process is demonstrated and fully characterized in a hard to etch materials etcher. CCTO sintered in powder shows a giant relative dielectric constant (10 5 ) measured at 1 MHz at room temperature. This feature is furthermore coupled with stability from 10 1 Hz to 10 6 Hz in a wide temperature range (100K - 600K). In principle, this property can allow to fabricate very high capacitance density condenser. Due to its perovskite multi-component structure, CCTO can be considered a hard to etch material. For high density capacitor fabrication, CCTO anisotropic etching is requested by using high density plasma. The behavior of etched CCTO was studied in a HRe- (High Density Reflected electron) plasma etcher using Cl 2 /Ar chemistry. The relationship between the etch rate and the Cl 2 /Ar ratio was also studied. The effects of RF MHz, KHz Power and pressure variation, the impact of HBr addiction to the Cl 2 /Ar chemistry on the CCTO etch rate and on its selectivity to Pt and photo resist was investigated.

Characterization of the high density plasma etching process of CCTO thin films for the fabrication of very high density capacitors

Energy Technology Data Exchange (ETDEWEB)

Altamore, C; Tringali, C; Sparta' , N; Marco, S Di; Grasso, A; Ravesi, S [STMicroelectronics, Industial and Multi-segment Sector R and D, Catania (Italy)

2010-02-15

In this work the feasibility of CCTO (Calcium Copper Titanate) patterning by etching process is demonstrated and fully characterized in a hard to etch materials etcher. CCTO sintered in powder shows a giant relative dielectric constant (10{sup 5}) measured at 1 MHz at room temperature. This feature is furthermore coupled with stability from 10{sup 1} Hz to 10{sup 6} Hz in a wide temperature range (100K - 600K). In principle, this property can allow to fabricate very high capacitance density condenser. Due to its perovskite multi-component structure, CCTO can be considered a hard to etch material. For high density capacitor fabrication, CCTO anisotropic etching is requested by using high density plasma. The behavior of etched CCTO was studied in a HRe- (High Density Reflected electron) plasma etcher using Cl{sub 2}/Ar chemistry. The relationship between the etch rate and the Cl{sub 2}/Ar ratio was also studied. The effects of RF MHz, KHz Power and pressure variation, the impact of HBr addiction to the Cl{sub 2}/Ar chemistry on the CCTO etch rate and on its selectivity to Pt and photo resist was investigated.

Compensated readout for high-density MOS-gated memristor crossbar array

KAUST Repository

Zidan, Mohammed A.

2015-01-01

Leakage current is one of the main challenges facing high-density MOS-gated memristor arrays. In this study, we show that leakage current ruins the memory readout process for high-density arrays, and analyze the tradeoff between the array density and its power consumption. We propose a novel readout technique and its underlying circuitry, which is able to compensate for the transistor leakage-current effect in the high-density gated memristor array.

Canine Fecal Contamination in a Metropolitan Area (Milan, North-Western Italy): Prevalence of Intestinal Parasites and Evaluation of Health Risks

Science.gov (United States)

Zanzani, Sergio Aurelio; Di Cerbo, Anna Rita; Gazzonis, Alessia Libera; Genchi, Marco; Rinaldi, Laura; Musella, Vincenzo; Cringoli, Giuseppe

2014-01-01

Intestinal parasites of dogs represent a serious threat to human health due to their zoonotic potential. Thus, metropolitan areas presenting high concentrations of pets and urban fecal contamination on public areas are at sanitary risk. Major aim of this survey was to determine prevalence of zoonotic parasites in dog fecal samples collected from public soil of Milan (north-western Italy). Differences in parasites prevalence distribution were explored by a geographical information system- (GIS-) based approach, and risk factors (human density, sizes of green parks, and dog areas) were considered. The metropolitan area was divided into 157 rectangular subareas and sampling was performed following a 1-kilometer straight transect. A total of 463 fecal samples were analyzed using centrifugation-flotation technique and ELISA to detect Giardia and Cryptosporidium coproantigens. A widespread fecal contamination of soil was highlighted, being fecal samples found in 86.8% of the subareas considered. The overall prevalence of intestinal parasites was 16.63%. Zoonotic parasites were found, such as Trichuris vulpis (3.67%), Toxocara canis (1.72%), Strongyloides stercoralis (0.86%), Ancylostomatidae (0.43%), and Dipylidium caninum (0.43%). Giardia duodenalis was the most prevalent zoonotic protozoa (11.06%), followed by Cryptosporidium (1.10%). Faeces from subareas characterized by broad green areas showed to be particularly prone to infection. PMID:25478583

Canine Fecal Contamination in a Metropolitan Area (Milan, North-Western Italy: Prevalence of Intestinal Parasites and Evaluation of Health Risks

Directory of Open Access Journals (Sweden)

Sergio Aurelio Zanzani

2014-01-01

Full Text Available Intestinal parasites of dogs represent a serious threat to human health due to their zoonotic potential. Thus, metropolitan areas presenting high concentrations of pets and urban fecal contamination on public areas are at sanitary risk. Major aim of this survey was to determine prevalence of zoonotic parasites in dog fecal samples collected from public soil of Milan (north-western Italy. Differences in parasites prevalence distribution were explored by a geographical information system- (GIS- based approach, and risk factors (human density, sizes of green parks, and dog areas were considered. The metropolitan area was divided into 157 rectangular subareas and sampling was performed following a 1-kilometer straight transect. A total of 463 fecal samples were analyzed using centrifugation-flotation technique and ELISA to detect Giardia and Cryptosporidium coproantigens. A widespread fecal contamination of soil was highlighted, being fecal samples found in 86.8% of the subareas considered. The overall prevalence of intestinal parasites was 16.63%. Zoonotic parasites were found, such as Trichuris vulpis (3.67%, Toxocara canis (1.72%, Strongyloides stercoralis (0.86%, Ancylostomatidae (0.43%, and Dipylidium caninum (0.43%. Giardia duodenalis was the most prevalent zoonotic protozoa (11.06%, followed by Cryptosporidium (1.10%. Faeces from subareas characterized by broad green areas showed to be particularly prone to infection.

Cell fractionation of parasitic protozoa: a review

Directory of Open Access Journals (Sweden)

Souza Wanderley de

2003-01-01

Full Text Available Cell fractionation, a methodological strategy for obtaining purified organelle preparations, has been applied successfully to parasitic protozoa by a number of investigators. Here we present and discuss the work of several groups that have obtained highly purified subcellular fractions from trypanosomatids, Apicomplexa and trichomonads, and whose work have added substantially to our knowledge of the cell biology of these parasites.

Numerical analysis of energy density and particle density in high energy heavy-ion collisions

International Nuclear Information System (INIS)

Fu Yuanyong; Lu Zhongdao

2004-01-01

Energy density and particle density in high energy heavy-ion collisions are calculated with infinite series expansion method and Gauss-Laguerre formulas in numerical integration separately, and the results of these two methods are compared, the higher terms and linear terms in series expansion are also compared. The results show that Gauss-Laguerre formulas is a good method in calculations of high energy heavy-ion collisions. (author)

High prevalence of diarrhoegenic intestinal parasite infections among non-ART HIV patients in Fitche Hospital, Ethiopia.

Directory of Open Access Journals (Sweden)

Haileeyesus Adamu

Full Text Available BACKGROUND: HIV infection has been modifying both the epidemiology and outcome of parasite infections. Hence, this study was undertaken to determine the prevalence of Cryptosporidium and other intestinal parasite infections among HIV positives with and without Antiretroviral Treatment(ART and its association with CD4+ T-cell count. METHODS: A cross-sectional study was conducted at Fitche hospital focusing on HIV positives who came to hospital for follow-ups. A total of 378 HIV positive persons with and without ART participated in the study. Data on socio-demographic factors and diarrhoea status were obtained by interviewing all 214 with ART and 164 without ART. Stool samples were collected from all patients and examined for intestinal parasites using direct, formol-ether and modified acid-fast staining techniques. RESULTS: The prevalence of intestinal parasite infections in this study was significantly higher among HIV positive persons not on ART. Specifically, the rate of infection with Cryptosporidium species, Blastocystis spp., Giardia lamblia, and Entamoeba histolytica/E. dispar were higher, particularly in those with CD4+ T-cell counts less than 200 cells/µL. Fifty seven percent of the study participants were on ART. Out of these 164/378 (43% of the non-ART study participants were infected with at least one intestinal parasite species. Significant association was observed between lower CD4+ T-cell count (<200 cells/µL and the prevalence of Cryptosporidium spp. and Blastocystis spp. The two parasites were significantly more prevalent in HIV positive non-ART patients. CONCLUSION: HIV infection increased the risk of having Cryptosporidium and other intestinal parasites and diarrhoea. Therefore, raising HIV positive's immune status and screening for intestinal parasites is important. This study showed that patients who are taking ART had a lower prevalence of diarrhoea causing parasites and Cryptosporidium suggesting that ART through

Parasites in marine food webs

Science.gov (United States)

Lafferty, Kevin D.

2013-01-01

Most species interactions probably involve parasites. This review considers the extent to which marine ecologists should consider parasites to fully understand marine communities. Parasites are influential parts of food webs in estuaries, temperate reefs, and coral reefs, but their ecological importance is seldom recognized. Though difficult to observe, parasites can have substantial biomass, and they can be just as common as free-living consumers after controlling for body mass and trophic level. Parasites have direct impacts on the energetics of their hosts and some affect host behaviors, with ecosystem-level consequences. Although they cause disease, parasites are sensitive components of ecosystems. In particular, they suffer secondary extinctions due to biodiversity loss. Some parasites can also return to a system after habitat restoration. For these reasons, parasites can make good indicators of ecosystem integrity. Fishing can indirectly increase or decrease parasite populations and the effects of climate change on parasites are likely to be equally as complex.

Distribution and transmission of the highly pathogenic parasite Ichthyophonus in marine fishes of Alaska

Science.gov (United States)

Gregg, Jacob L.; Grady, Courtney A.; Thompson, Rachel L.; Purcell, Maureen K.; Friedman, Carolyn S.; Hershberger, Paul K.

2014-01-01

A combination of field surveys, molecular typing, and laboratory experiments were used to improve our understanding of the distribution and transmission mechanisms of fish parasites in the genus Ichthyophonus. Ichthyophonus spp. infections were detected from the Bering Sea to the coast of Oregon in 10 of 13 host species surveyed. Sequences of rDNA extracted from these isolates indicate that a ubiquitous Ichthyophonus type occurs in the NE Pacific Ocean and Bering Sea and accounts for nearly all the infections encountered. Among NE Pacific isolates, only parasites from yellowtail rockfish and Puget Sound rockfish varied at the DNA locus examined. These data suggest that a single source population of these parasites is available to fishes in diverse niches across a wide geographic range. A direct life cycle within a common forage species could account for the relatively low parasite diversity we encountered. In the laboratory we tested the hypothesis that waterborne transmission occurs among Pacific herring, a common NE Pacific forage species. No horizontal transmission occurred during a four-month cohabitation experiment involving infected herring and conspecific sentinels. The complete life cycle of Ichthyophonus spp. is not known, but these results suggest that system-wide processes maintain a relatively homogenous parasite population.

Pitting of malaria parasites and spherocyte formation

Directory of Open Access Journals (Sweden)

Gichuki Charity W

2006-07-01

Full Text Available Abstract Background A high prevalence of spherocytes was detected in blood smears of children enrolled in a case control study conducted in the malaria holoendemic Lake Victoria basin. It was speculated that the spherocytes reflect intraerythrocytic removal of malarial parasites with a concurrent removal of RBC membrane through a process analogous to pitting of intraerythrocytic inclusion bodies. Pitting and re-circulation of RBCs devoid of malaria parasites could be a host mechanism for parasite clearance while minimizing the anaemia that would occur were the entire parasitized RBC removed. The prior demonstration of RBCs containing ring-infected erythrocyte surface antigen (pf 155 or RESA but no intracellular parasites, support the idea of pitting. Methods An in vitro model was developed to examine the phenomenon of pitting and spherocyte formation in Plasmodium falciparum infected RBCs (iRBC co-incubated with human macrophages. In vivo application of this model was evaluated using blood specimens from patients attending Kisumu Ditrict Hospital. RBCs were probed with anti-RESA monoclonal antibody and a DNA stain (propidium iodide. Flow cytometry and fluorescent microscopy was used to compare RBCs containing both the antigen and the parasites to those that were only RESA positive. Results Co-incubation of iRBC and tumor necrosis factor-alpha activated macrophages led to pitting (14% ± 1.31% macrophages with engulfed trophozoites as opposed to erythrophagocytosis (5.33% ± 0.95% (P Conclusion It is proposed that in malaria holoendemic areas where prevalence of asexual stage parasites approaches 100% in children, RBCs with pitted parasites are re-circulated and pitting may produce spherocytes.

Parasitic diseases

International Nuclear Information System (INIS)

Rozenshtraukh, L.S.

1983-01-01

Foundations of roentgenological semiotics of parasitic diseases of lungs, w hich are of the greatest practical value, are presented. Roentgenological pictu res of the following parasitic diseases: hydatid and alveolar echinococcosis, pa ragonimiasis, toxoplasmosis, ascariasis, amebiasis, bilharziasis (Schistosomias is) of lungs, are considered

High density regimes and beta limits in JET

International Nuclear Information System (INIS)

Smeulders, P.

1990-01-01

Results are first presented on the density limit in JET discharges with graphite (C), Be gettered graphite and Be limiters. There is a clear improvement in the case of Be limiters. The Be gettered phase showed no increase in the gas fueled density limit, except with Ion Cyclotron Resonance Heating (ICRH), but, the limit changed character. During MARFE-formation, any further increase in density was prevented, leading to a soft density limit. The soft density limit was a function of input power and impurity content with a week dependence on q. Helium and pellet fuelled discharges exceeded the gas-fuelled global density limits, but essentially had the same edge limit. In the second part, results are presented of high β operation in low-B Double-Null (DN) X-point configurations with Be-gettered carbon target plates. The Troyon limit was reached during H-mode discharges and toroidal β values of 5.5% were obtained. At high beta, the sawteeth were modified and characterised by very rapid heat-waves and fishbone-like pre- and post-cursors with strongly ballooning character. 17 refs., 5 figs

The use of low density high accuracy (LDHA) data for correction of high density low accuracy (HDLA) point cloud

Science.gov (United States)

Rak, Michal Bartosz; Wozniak, Adam; Mayer, J. R. R.

2016-06-01

Coordinate measuring techniques rely on computer processing of coordinate values of points gathered from physical surfaces using contact or non-contact methods. Contact measurements are characterized by low density and high accuracy. On the other hand optical methods gather high density data of the whole object in a short time but with accuracy at least one order of magnitude lower than for contact measurements. Thus the drawback of contact methods is low density of data, while for non-contact methods it is low accuracy. In this paper a method for fusion of data from two measurements of fundamentally different nature: high density low accuracy (HDLA) and low density high accuracy (LDHA) is presented to overcome the limitations of both measuring methods. In the proposed method the concept of virtual markers is used to find a representation of pairs of corresponding characteristic points in both sets of data. In each pair the coordinates of the point from contact measurements is treated as a reference for the corresponding point from non-contact measurement. Transformation enabling displacement of characteristic points from optical measurement to their match from contact measurements is determined and applied to the whole point cloud. The efficiency of the proposed algorithm was evaluated by comparison with data from a coordinate measuring machine (CMM). Three surfaces were used for this evaluation: plane, turbine blade and engine cover. For the planar surface the achieved improvement was of around 200 μm. Similar results were obtained for the turbine blade but for the engine cover the improvement was smaller. For both freeform surfaces the improvement was higher for raw data than for data after creation of mesh of triangles.

Host partitioning by parasites in an intertidal crustacean community.

Science.gov (United States)

Koehler, Anson V; Poulin, Robert

2010-10-01

Patterns of host use by parasites throughout a guild community of intermediate hosts can depend on several biological and ecological factors, including physiology, morphology, immunology, and behavior. We looked at parasite transmission in the intertidal crustacean community of Lower Portobello Bay, Dunedin, New Zealand, with the intent of: (1) mapping the flow of parasites throughout the major crustacean species, (2) identifying hosts that play the most important transmission role for each parasite, and (3) assessing the impact of parasitism on host populations. The most prevalent parasites found in 14 species of crustaceans (635 specimens) examined were the trematodes Maritrema novaezealandensis and Microphallus sp., the acanthocephalans Profilicollis spp., the nematode Ascarophis sp., and an acuariid nematode. Decapods were compatible hosts for M. novaezealandensis, while other crustaceans demonstrated lower host suitability as shown by high levels of melanized and immature parasite stages. Carapace thickness, gill morphology, and breathing style may contribute to the differential infection success of M. novaezealandensis and Microphallus sp. in the decapod species. Parasite-induced host mortality appears likely with M. novaezealandensis in the crabs Austrohelice crassa, Halicarcinus varius, Hemigrapsus sexdentatus, and Macrophthalmus hirtipes, and also with Microphallus sp. in A. crassa. Overall, the different parasite species make different use of available crustacean intermediate hosts and possibly contribute to intertidal community structure.

High energy density capacitors fabricated by thin film technology

International Nuclear Information System (INIS)

Barbee, T W; Johnson, G W; Wagner, A V.

1999-01-01

Low energy density in conventional capacitors severely limits efforts to miniaturize power electronics and imposes design limitations on electronics in general. We have successfully applied physical vapor deposition technology to greatly increase capacitor energy density. The high dielectric breakdown strength we have achieved in alumina thin films allows high energy density to be achieved with this moderately low dielectric constant material. The small temperature dependence of the dielectric constant, and the high reliability, high resistivity, and low dielectric loss of Al 2 O 3 , make it even more appealing. We have constructed single dielectric layer thin film capacitors and shown that they can be stacked to form multilayered structures with no loss in yield for a given capacitance. Control of film growth morphology is critical for achieving the smooth, high quality interfaces between metal and dielectric necessary for device operation at high electric fields. Most importantly, high rate deposition with extremely low particle generation is essential for achieving high energy storage at a reasonable cost. This has been achieved by reactive magnetron sputtering in which the reaction to form the dielectric oxide has been confined to the deposition surface. By this technique we have achieved a yield of over 50% for 1 cm 2 devices with an energy density of 14 J per cubic centimeter of Al 2 O 3 dielectric material in 1.2 kV, 4 nF devices. By further reducing defect density and increasing the dielectric constant of the material, we will be able to increase capacitance and construct high energy density devices to meet the requirements of applications in power electronics

Mate Limitation in Fungal Plant Parasites Can Lead to Cyclic Epidemics in Perennial Host Populations.

Science.gov (United States)

Ravigné, Virginie; Lemesle, Valérie; Walter, Alicia; Mailleret, Ludovic; Hamelin, Frédéric M

2017-03-01

Fungal plant parasites represent a growing concern for biodiversity and food security. Most ascomycete species are capable of producing different types of infectious spores both asexually and sexually. Yet the contributions of both types of spores to epidemiological dynamics have still to been fully researched. Here we studied the effect of mate limitation in parasites which perform both sexual and asexual reproduction in the same host. Since mate limitation implies positive density dependence at low population density, we modeled the dynamics of such species with both density-dependent (sexual) and density-independent (asexual) transmission rates. A first simple SIR model incorporating these two types of transmission from the infected compartment, suggested that combining sexual and asexual spore production can generate persistently cyclic epidemics in a significant part of the parameter space. It was then confirmed that cyclic persistence could occur in realistic situations by parameterizing a more detailed model fitting the biology of the Black Sigatoka disease of banana, for which literature data are available. We discuss the implications of these results for research on and management of Sigatoka diseases of banana.

HIGH DENSITY QCD WITH HEAVY-IONS

CERN Multimedia

The Addendum 1 to Volume 2 of the CMS Physics TDR has been published The Heavy-Ion analysis group completed the writing of a TDR summarizing the CMS plans in using heavy ion collisions to study high density QCD. The document was submitted to the LHCC in March and presented in the Open Session of the LHCC on May 9th. The study of heavy-ion physics at the LHC is promising to be very exciting. LHC will open a new energy frontier in ultra-relativistic heavy-ion physics. The collision energy of heavy nuclei at sNN = 5.5 TeV will be thirty times larger than what is presently available at RHIC. We will certainly probe quark and gluon matter at unprecedented values of energy density. The prime goal of this research programme is to study the fundamental theory of the strong interaction - Quantum Chromodynamics (QCD) - in extreme conditions of temperature, density and parton momentum fraction (low-x). Such studies, with impressive experimental and theoretical advances in recent years thanks to the wealth of high-qua...

Epidemiological assessment of intestinal parasitic infections in dogs at animal shelter in Veracruz, Mexico

Directory of Open Access Journals (Sweden)

Cosme Alvarado-Esquivel

2015-01-01

Conclusions: A high prevalence of intestinal parasites was found in the dogs studied. This suggests that the environment is highly contaminated with intestinal parasites. Preventive and therapeutic measures should be taken against infection with intestinal parasites in dogs in this region.

An x-ray backlit Talbot-Lau deflectometer for high-energy-density electron density diagnostics

Science.gov (United States)

Valdivia, M. P.; Stutman, D.; Stoeckl, C.; Theobald, W.; Mileham, C.; Begishev, I. A.; Bromage, J.; Regan, S. P.

2016-02-01

X-ray phase-contrast techniques can measure electron density gradients in high-energy-density plasmas through refraction induced phase shifts. An 8 keV Talbot-Lau interferometer consisting of free standing ultrathin gratings was deployed at an ultra-short, high-intensity laser system using K-shell emission from a 1-30 J, 8 ps laser pulse focused on thin Cu foil targets. Grating survival was demonstrated for 30 J, 8 ps laser pulses. The first x-ray deflectometry images obtained under laser backlighting showed up to 25% image contrast and thus enabled detection of electron areal density gradients with a maximum value of 8.1 ± 0.5 × 1023 cm-3 in a low-Z millimeter sized sample. An electron density profile was obtained from refraction measurements with an error of x-ray source-size, similar to conventional radiography.

Epilepsy and tropical parasitic infections in Sub-Saharan Africa: a ...

African Journals Online (AJOL)

Saharan Africa is associated with the high prevalence of parasitic infections affecting the central nervous system. Though epidemiological evidence suggests an association between parasitic infections and epilepsy, the biological causal ...

Performance of conversion efficiency of a crystalline silicon solar cell with base doping density

Directory of Open Access Journals (Sweden)

Gokhan Sahin

Full Text Available In this study, we investigate theoretically the electrical parameters of a crystalline silicon solar cell in steady state. Based on a one-dimensional modeling of the cell, the short circuit current density, the open circuit voltage, the shunt and series resistances and the conversion efficiency are calculated, taking into account the base doping density. Either the I-V characteristic, series resistance, shunt resistance and conversion efficiency are determined and studied versus base doping density. The effects applied of base doping density on these parameters have been studied. The aim of this work is to show how short circuit current density, open circuit voltage and parasitic resistances are related to the base doping density and to exhibit the role played by those parasitic resistances on the conversion efficiency of the crystalline silicon solar. Keywords: Crystalline silicon solar cell, Base doping density, Series resistance, Shunt resistance, Conversion efficiency

How have fisheries affected parasite communities?

Science.gov (United States)

Wood, Chelsea L; Lafferty, Kevin D

2015-01-01

To understand how fisheries affect parasites, we conducted a meta-analysis of studies that contrasted parasite assemblages in fished and unfished areas. Parasite diversity was lower in hosts from fished areas. Larger hosts had a greater abundance of parasites, suggesting that fishing might reduce the abundance of parasites by selectively removing the largest, most heavily parasitized individuals. After controlling for size, the effect of fishing on parasite abundance varied according to whether the host was fished and the parasite's life cycle. Parasites of unfished hosts were more likely to increase in abundance in response to fishing than were parasites of fished hosts, possibly due to compensatory increases in the abundance of unfished hosts. While complex life cycle parasites tended to decline in abundance in response to fishing, directly transmitted parasites tended to increase. Among complex life cycle parasites, those with fished hosts tended to decline in abundance in response to fishing, while those with unfished hosts tended to increase. However, among directly transmitted parasites, responses did not differ between parasites with and without fished hosts. This work suggests that parasite assemblages are likely to change substantially in composition in increasingly fished ecosystems, and that parasite life history and fishing status of the host are important in predicting the response of individual parasite species or groups to fishing.

Chapter 7: High-Density H-Mode Operation in ASDEX Upgrade

International Nuclear Information System (INIS)

Stober, Joerg Karl; Lang, Peter Thomas; Mertens, Vitus

2003-01-01

Recent results are reported on the maximum achievable H-mode density and the behavior of pedestal density and central density peaking as this limit is approached. The maximum achievable H-mode density roughly scales as the Greenwald density, though a dependence on B t is clearly observed. In contrast to the stiff temperature profiles, the density profiles seem to allow more shape variation and especially with high-field-side pellet-injection, strongly peaked profiles with good confinement have been achieved. Also, spontaneous density peaking at high densities is observed in ASDEX Upgrade, which is related to the generally observed large time constants for the density profile equilibration. The equilibrated density profile shapes depend strongly on the heat-flux profile in the sense that central heating leads to significantly flatter profiles

Viruses of parasites as actors in the parasite-host relationship: A "ménage à trois".

Science.gov (United States)

Gómez-Arreaza, Amaranta; Haenni, Anne-Lise; Dunia, Irene; Avilán, Luisana

2017-02-01

The complex parasite-host relationship involves multiple mechanisms. Moreover, parasites infected by viruses modify this relationship adding more complexity to the system that now comprises three partners. Viruses infecting parasites were described several decades ago. However, until recently little was known about the viruses involved and their impact on the resulting disease caused to the hosts. To clarify this situation, we have concentrated on parasitic diseases caused to humans and on how virus-infected parasites could alter the symptoms inflicted on the human host. It is clear that the effect caused to the human host depends on the virus and on the parasite it has infected. Consequently, the review is divided as follows: Viruses with a possible effect on the virulence of the parasite. This section reviews pertinent articles showing that infection of parasites by viruses might increase the detrimental effect of the tandem virus-parasite on the human host (hypervirulence) or decrease virulence of the parasite (hypovirulence). Parasites as vectors affecting the transmission of viruses. In some cases, the virus-infected parasite might facilitate the transfer of the virus to the human host. Parasites harboring viruses with unidentified effects on their host. In spite of recently renewed interest in parasites in connection with their viruses, there still remains a number of cases in which the effect of the virus of a given parasite on the human host remains ambiguous. The triangular relationship between the virus, the parasite and the host, and the modulation of the pathogenicity and virulence of the parasites by viruses should be taken into account in the rationale of fighting against parasites. Copyright © 2016 Elsevier B.V. All rights reserved.

Functions of myosin motors tailored for parasitism

DEFF Research Database (Denmark)

Mueller, Christina; Graindorge, Arnault; Soldati-Favre, Dominique

2017-01-01

Myosin motors are one of the largest protein families in eukaryotes that exhibit divergent cellular functions. Their roles in protozoans, a diverse group of anciently diverged, single celled organisms with many prominent members known to be parasitic and to cause diseases in human and livestock......, are largely unknown. In the recent years many different approaches, among them whole genome sequencing, phylogenetic analyses and functional studies have increased our understanding on the distribution, protein architecture and function of unconventional myosin motors in protozoan parasites. In Apicomplexa......, myosins turn out to be highly specialized and to exhibit unique functions tailored to accommodate the lifestyle of these parasites....

Experimental study of high density foods for the Space Operations Center

Science.gov (United States)

Ahmed, S. M.

1981-01-01

The experimental study of high density foods for the Space Operations Center is described. A sensory evaluation of the high density foods was conducted first to test the acceptability of the products. A shelf-life study of the high density foods was also conducted for three different time lengths at three different temperatures. The nutritional analysis of the high density foods is at present incomplete.

Fluorescent Fe K Emission from High Density Accretion Disks

Science.gov (United States)

Bautista, Manuel; Mendoza, Claudio; Garcia, Javier; Kallman, Timothy R.; Palmeri, Patrick; Deprince, Jerome; Quinet, Pascal

2018-06-01

Iron K-shell lines emitted by gas closely orbiting black holes are observed to be grossly broadened and skewed by Doppler effects and gravitational redshift. Accordingly, models for line profiles are widely used to measure the spin (i.e., the angular momentum) of astrophysical black holes. The accuracy of these spin estimates is called into question because fitting the data requires very high iron abundances, several times the solar value. Meanwhile, no plausible physical explanation has been proffered for why these black hole systems should be so iron rich. The most likely explanation for the super-solar iron abundances is a deficiency in the models, and the leading candidate cause is that current models are inapplicable at densities above 1018 cm-3. We study the effects of high densities on the atomic parameters and on the spectral models for iron ions. At high densities, Debye plasma can affect the effective atomic potential of the ions, leading to observable changes in energy levels and atomic rates with respect to the low density case. High densities also have the effec of lowering energy the atomic continuum and reducing the recombination rate coefficients. On the spectral modeling side, high densities drive level populations toward a Boltzman distribution and very large numbers of excited atomic levels, typically accounted for in theoretical spectral models, may contribute to the K-shell spectrum.

Host and parasite morphology influence congruence between host and parasite phylogenies.

Science.gov (United States)

Sweet, Andrew D; Bush, Sarah E; Gustafsson, Daniel R; Allen, Julie M; DiBlasi, Emily; Skeen, Heather R; Weckstein, Jason D; Johnson, Kevin P

2018-03-23

Comparisons of host and parasite phylogenies often show varying degrees of phylogenetic congruence. However, few studies have rigorously explored the factors driving this variation. Multiple factors such as host or parasite morphology may govern the degree of phylogenetic congruence. An ideal analysis for understanding the factors correlated with congruence would focus on a diverse host-parasite system for increased variation and statistical power. In this study, we focused on the Brueelia-complex, a diverse and widespread group of feather lice that primarily parasitise songbirds. We generated a molecular phylogeny of the lice and compared this tree with a phylogeny of their avian hosts. We also tested for the contribution of each host-parasite association to the overall congruence. The two trees overall were significantly congruent, but the contribution of individual associations to this congruence varied. To understand this variation, we developed a novel approach to test whether host, parasite or biogeographic factors were statistically associated with patterns of congruence. Both host plumage dimorphism and parasite ecomorphology were associated with patterns of congruence, whereas host body size, other plumage traits and biogeography were not. Our results lay the framework for future studies to further elucidate how these factors influence the process of host-parasite coevolution. Copyright © 2018 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

Phenomenology of high density disruptions in the TFTR tokamak

International Nuclear Information System (INIS)

Fredrickson, E.D.; McGuire, K.M.; Bell, M.G.

1993-01-01

Studies of high density disruptions on TFTR, including a comparison of minor and major disruptions at high density, provide important new information regarding the nature of the disruption mechanism. Further, for the first time, an (m,n)=(1,1) 'cold bubble' precursor to high density disruptions has been experimentally observed in the electron temperature profile. The precursor to major disruptions resembles the 'vacuum bubble' model of disruptions first proposed by B.B. Kadomtsev and O.P. Pogutse (Sov. Phys. - JETP 38 (1974) 283). (author). Letter-to-the-editor. 25 refs, 3 figs

Parasites as prey in aquatic food webs: implications for predator infection and parasite transmission

NARCIS (Netherlands)

Thieltges, D.W.; Amundsen, P.-A.; Hechinger, R.F.; Johnson, P.T.J.; Lafferty, K.D.; Mouritsen, K.N.; Preston, D.L.; Reise, K.; Zander, C.D.; Poulin, R.

2013-01-01

While the recent inclusion of parasites into food-web studies has highlighted the role of parasites as consumers, there is accumulating evidence that parasites can also serve as prey for predators. Here we investigated empirical patterns of predation on parasites and their relationships with

High Energy Density Polymer Film Capacitors

National Research Council Canada - National Science Library

Boufelfel, Ali

2006-01-01

High-energy-density capacitors that are compact and light-weight are extremely valuable in a number of critical DoD systems that include portable field equipment, pulsed lasers, detection equipment...

Parasites of importance for human health in Nigerian dogs: high prevalence and limited knowledge of pet owners.

Science.gov (United States)

Ugbomoiko, Uade Samuel; Ariza, Liana; Heukelbach, Jorg

2008-12-09

Dogs are the most common pet animals worldwide. They may harbour a wide range of parasites with zoonotic potential, thus causing a health risk to humans. In Nigeria, epidemiological knowledge on these parasites is limited. In a community-based study, we examined 396 dogs in urban and rural areas of Ilorin (Kwara State, Central Nigeria) for ectoparasites and intestinal helminths. In addition, a questionnaire regarding knowledge and practices was applied to pet owners. Nine ectoparasite species belonging to four taxa and six intestinal helminth species were identified: fleas (Ctenocephalides canis, Pulex irritans, Tunga penetrans), mites (Demodex canis, Otodectes sp., Sarcoptes scabiei var. canis), ticks (Rhipicephalus sanguineus, Ixodes sp.), and lice (Trichodectes canis); and Toxocara canis, Ancylostoma sp., Trichuris vulpis, Dipylidium caninum, Taenidae and Strongyloides sp. Overall prevalence of ectoparasites was 60.4% and of intestinal helminths 68.4%. The occurrence of C. canis, R. sanguineus, T. canis, Ancylostoma sp. and T. vulpis was most common (prevalence 14.4% to 41.7%). Prevalence patterns in helminths were age-dependent, with T. canis showing a decreasing prevalence with age of host, and a reverse trend in other parasite species. Knowledge regarding zoonoses was very limited and the diseases not considered a major health problem. Treatment with antiparasitic drugs was more frequent in urban areas. Parasites of importance for human health were highly prevalent in Nigerian dogs. Interventions should include health education provided to dog owners and the establishment of a program focusing on zoonotic diseases.

Short-sighted evolution of virulence in parasitic honeybee workers ( Apis mellifera capensis Esch.)

Science.gov (United States)

Moritz, Robin F. A.; Pirk, Christian W. W.; Hepburn, H. Randall; Neumann, Peter

2008-06-01

The short-sighted selection hypothesis for parasite virulence predicts that winners of within-host competition are poorer at transmission to new hosts. Social parasitism by self-replicating, female-producing workers occurs in the Cape honeybee Apis mellifera capensis, and colonies of other honeybee subspecies are susceptible hosts. We found high within-host virulence but low transmission rates in a clone of social parasitic A. m. capensis workers invading the neighbouring subspecies A. m. scutellata. In contrast, parasitic workers from the endemic range of A. m. capensis showed low within-host virulence but high transmission rates. This suggests a short-sighted selection scenario for the host-parasite co-evolution in the invasive range of the Cape honeybee, probably facilitated by beekeeping-assisted parasite transmission in apiaries.

Blood parasites in reptiles imported to Germany.

Science.gov (United States)

Halla, Ursula; Ursula, Halla; Korbel, Rüdiger; Rüdiger, Korbel; Mutschmann, Frank; Frank, Mutschmann; Rinder, Monika; Monika, Rinder

2014-12-01

Though international trade is increasing, the significance of imported reptiles as carriers of pathogens with relevance to animal and human health is largely unknown. Reptiles imported to Germany were therefore investigated for blood parasites using light microscopy, and the detected parasites were morphologically characterized. Four hundred ten reptiles belonging to 17 species originating from 11 Asian, South American and African countries were included. Parasites were detected in 117 (29%) of individual reptiles and in 12 species. Haemococcidea (Haemogregarina, Hepatozoon, Schellackia) were found in 84% of snakes (Python regius, Corallus caninus), 20% of lizards (Acanthocercus atricollis, Agama agama, Kinyongia fischeri, Gekko gecko) and 50% of turtles (Pelusios castaneus). Infections with Hematozoea (Plasmodium, Sauroplasma) were detected in 14% of lizards (Acanthocercus atricollis, Agama agama, Agama mwanzae, K. fischeri, Furcifer pardalis, Xenagama batillifera, Acanthosaura capra, Physignathus cocincinus), while those with Kinetoplastea (Trypanosoma) were found in 9% of snakes (Python regius, Corallus caninus) and 25 % of lizards (K. fischeri, Acanthosaura capra, G. gecko). Nematoda including filarial larvae parasitized in 10% of lizards (Agama agama, Agama mwanzae, K. fischeri, Fu. pardalis, Physignathus cocincinus). Light microscopy mostly allowed diagnosis of the parasites' genus, while species identification was not possible because of limited morphological characteristics available for parasitic developmental stages. The investigation revealed a high percentage of imported reptiles being carriers of parasites while possible vectors and pathogenicity are largely unknown so far. The spreading of haemoparasites thus represents an incalculable risk for pet reptiles, native herpetofauna and even human beings.

Host-Parasite Interaction: Parasite-Derived and -Induced Proteases That Degrade Human Extracellular Matrix

Directory of Open Access Journals (Sweden)

Carolina Piña-Vázquez

2012-01-01

Full Text Available Parasitic protozoa are among the most important pathogens worldwide. Diseases such as malaria, leishmaniasis, amoebiasis, giardiasis, trichomoniasis, and trypanosomiasis affect millions of people. Humans are constantly threatened by infections caused by these pathogens. Parasites engage a plethora of surface and secreted molecules to attach to and enter mammalian cells. The secretion of lytic enzymes by parasites into host organs mediates critical interactions because of the invasion and destruction of interstitial tissues, enabling parasite migration to other sites within the hosts. Extracellular matrix is a complex, cross-linked structure that holds cells together in an organized assembly and that forms the basement membrane lining (basal lamina. The extracellular matrix represents a major barrier to parasites. Therefore, the evolution of mechanisms for connective-tissue degradation may be of great importance for parasite survival. Recent advances have been achieved in our understanding of the biochemistry and molecular biology of proteases from parasitic protozoa. The focus of this paper is to discuss the role of protozoan parasitic proteases in the degradation of host ECM proteins and the participation of these molecules as virulence factors. We divide the paper into two sections, extracellular and intracellular protozoa.

High density matter at RHIC

Indian Academy of Sciences (India)

QCD predicts a phase transition between hadronic matter and a quark-gluon plasma at high energy density. The relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory is a new facility dedicated to the experimental study of matter under extreme conditions. Already the first round of experimental results at ...

Medicinal Plants: A Source of Anti-Parasitic Secondary Metabolites

Directory of Open Access Journals (Sweden)

Michael Wink

2012-10-01

Full Text Available This review summarizes human infections caused by endoparasites, including protozoa, nematodes, trematodes, and cestodes, which affect more than 30% of the human population, and medicinal plants of potential use in their treatment. Because vaccinations do not work in most instances and the parasites have sometimes become resistant to the available synthetic therapeutics, it is important to search for alternative sources of anti-parasitic drugs. Plants produce a high diversity of secondary metabolites with interesting biological activities, such as cytotoxic, anti-parasitic and anti-microbial properties. These drugs often interfere with central targets in parasites, such as DNA (intercalation, alkylation, membrane integrity, microtubules and neuronal signal transduction. Plant extracts and isolated secondary metabolites which can inhibit protozoan parasites, such as Plasmodium, Trypanosoma, Leishmania, Trichomonas and intestinal worms are discussed. The identified plants and compounds offer a chance to develop new drugs against parasitic diseases. Most of them need to be tested in more detail, especially in animal models and if successful, in clinical trials.

Edge operational space for high density/high confinement ELMY H-modes in JET

International Nuclear Information System (INIS)

Sartori, R.; Saibene, G.; Loarte, A.

2002-01-01

This paper discusses how the proximity to the L-H threshold affects the confinement of ELMy H-modes at high density. The largest reduction in confinement at high density is observed at the transition from the Type I to the Type III ELMy regime. At medium plasma triangularity, δ≅0.3 (where δ is the average triangularity at the separatrix), JET experiments show that by increasing the margin above the L-H threshold power and maintaining the edge temperature above the critical temperature for the transition to Type III ELMs, it is possible to avoid the degradation of the pedestal pressure with density, normally observed at lower power. As a result, the range of achievable densities (both in the core and in the pedestal) is increased. At high power above the L-H threshold power the core density was equal to the Greenwald limit with H97≅0.9. There is evidence that a mixed regime of Type I and Type II ELMs has been obtained at this intermediate triangularity, possibly as a result of this increase in density. At higher triangularity, δ≅0.5, the power required to achieve similar results is lower. (author)

Trichomonas vaginalis exosomes deliver cargo to host cells and mediate host∶parasite interactions.

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Olivia Twu

Full Text Available Trichomonas vaginalis is a common sexually transmitted parasite that colonizes the human urogential tract where it remains extracellular and adheres to epithelial cells. Infections range from asymptomatic to highly inflammatory, depending on the host and the parasite strain. Here, we use a combination of methodologies including cell fractionation, immunofluorescence and electron microscopy, RNA, proteomic and cytokine analyses and cell adherence assays to examine pathogenic properties of T. vaginalis. We have found that T.vaginalis produces and secretes microvesicles with physical and biochemical properties similar to mammalian exosomes. The parasite-derived exosomes are characterized by the presence of RNA and core, conserved exosomal proteins as well as parasite-specific proteins. We demonstrate that T. vaginalis exosomes fuse with and deliver their contents to host cells and modulate host cell immune responses. Moreover, exosomes from highly adherent parasite strains increase the adherence of poorly adherent parasites to vaginal and prostate epithelial cells. In contrast, exosomes from poorly adherent strains had no measurable effect on parasite adherence. Exosomes from parasite strains that preferentially bind prostate cells increased binding of parasites to these cells relative to vaginal cells. In addition to establishing that parasite exosomes act to modulate host∶parasite interactions, these studies are the first to reveal a potential role for exosomes in promoting parasite∶parasite communication and host cell colonization.

Polyamine uptake by the intraerythrocytic malaria parasite, Plasmodium falciparum.

Science.gov (United States)

Niemand, J; Louw, A I; Birkholtz, L; Kirk, K

2012-09-01

Polyamines and the enzymes involved in their biosynthesis are present at high levels in rapidly proliferating cells, including cancer cells and protozoan parasites. Inhibition of polyamine biosynthesis in asexual blood-stage malaria parasites causes cytostatic arrest of parasite development under in vitro conditions, but does not cure infections in vivo. This may be due to replenishment of the parasite's intracellular polyamine pool via salvage of exogenous polyamines from the host. However, the mechanism(s) of polyamine uptake by the intraerythrocytic parasite are not well understood. In this study, the uptake of the polyamines, putrescine and spermidine, into Plasmodium falciparum parasites functionally isolated from their host erythrocyte was investigated using radioisotope flux techniques. Both putrescine and spermidine were taken up into isolated parasites via a temperature-dependent process that showed cross-competition between different polyamines. There was also some inhibition of polyamine uptake by basic amino acids. Inhibition of polyamine biosynthesis led to an increase in the total amount of putrescine and spermidine taken up from the extracellular medium. The uptake of putrescine and spermidine by isolated parasites was independent of extracellular Na(+) but increased with increasing external pH. Uptake also showed a marked dependence on the parasite's membrane potential, decreasing with membrane depolarization and increasing with membrane hyperpolarization. The data are consistent with polyamines being taken up into the parasite via an electrogenic uptake process, energised by the parasite's inwardly negative membrane potential. Copyright © 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Helminth parasites of amphibians from a rainforest reserve in ...

African Journals Online (AJOL)

Contrary to the earlier assumption that monogeneans in Nigeria were preferentially parasites of amphibians in drier environments such as the savanna, this study has shown that these parasites also infect amphibians in highly humid environments such as the rainforest. Monogeneans recorded included Metapolystoma ...

Parasite-Mediated Degradation of Synthetic Ozonide Antimalarials Impacts In Vitro Antimalarial Activity.

Science.gov (United States)

Giannangelo, Carlo; Stingelin, Lukas; Yang, Tuo; Tilley, Leann; Charman, Susan A; Creek, Darren J

2018-03-01

The peroxide bond of the artemisinins inspired the development of a class of fully synthetic 1,2,4-trioxolane-based antimalarials, collectively known as the ozonides. Similar to the artemisinins, heme-mediated degradation of the ozonides generates highly reactive radical species that are thought to mediate parasite killing by damaging critical parasite biomolecules. We examined the relationship between parasite dependent degradation and antimalarial activity for two ozonides, OZ277 (arterolane) and OZ439 (artefenomel), using a combination of in vitro drug stability and pulsed-exposure activity assays. Our results showed that drug degradation is parasite stage dependent and positively correlates with parasite load. Increasing trophozoite-stage parasitemia leads to substantially higher rates of degradation for both OZ277 and OZ439, and this is associated with a reduction in in vitro antimalarial activity. Under conditions of very high parasitemia (∼90%), OZ277 and OZ439 were rapidly degraded and completely devoid of activity in trophozoite-stage parasite cultures exposed to a 3-h drug pulse. This study highlights the impact of increasing parasite load on ozonide stability and in vitro antimalarial activity and should be considered when investigating the antimalarial mode of action of the ozonide antimalarials under conditions of high parasitemia. Copyright © 2018 American Society for Microbiology.

Growth limitation of Lemna minor due to high plant density

NARCIS (Netherlands)

Driever, S.M.; Nes, van E.H.; Roijackers, R.M.M.

2005-01-01

The effect of high population densities on the growth rate of Lemna minor (L.) was studied under laboratory conditions at 23°C in a medium with sufficient nutrients. At high population densities, we found a non-linear decreasing growth rate with increasing L. minor density. Above a L. minor biomass

Diagnosing Polyparasitism in a High-Prevalence Setting in Beira, Mozambique: Detection of Intestinal Parasites in Fecal Samples by Microscopy and Real-Time PCR.

Directory of Open Access Journals (Sweden)

Lynn Meurs

2017-01-01

Full Text Available Many different intestinal parasite species can co-occur in the same population. However, classic diagnostic tools can only frame a particular group of intestinal parasite species. Hence, one or two tests do not suffice to provide a complete picture of infecting parasite species in a given population. The present study investigated intestinal parasitic infections in Beira, Mozambique, i.e. in the informal settlement of Inhamudima. Diagnostic accuracy of five classical microscopy techniques and real-time PCR for the detection of a broad spectrum of parasites was compared.A cross-sectional population-based survey was performed. One stool sample per participant (n = 303 was examined by direct smear, formal-ether concentration (FEC, Kato smear, Baermann method, coproculture and real-time PCR. We found that virtually all people (96% harbored at least one helminth, and that almost half (49% harbored three helminths or more. Remarkably, Strongyloides stercoralis infections were widespread with a prevalence of 48%, and Ancylostoma spp. prevalence was higher than that of Necator americanus (25% versus 15%, the hookworm species that is often assumed to prevail in East-Africa. Among the microscopic techniques, FEC was able to detect the broadest spectrum of parasite species. However, FEC also missed a considerable number of infections, notably S. stercoralis, Schistosoma mansoni and G. intestinalis. PCR outperformed microscopy in terms of sensitivity and range of parasite species detected.We showed intestinal parasites-especially helminths-to be omnipresent in Inhamudima, Beira. However, it is a challenge to achieve high diagnostic sensitivity for all species. Classical techniques such as FEC are useful for the detection of some intestinal helminth species, but they lack sensitivity for other parasite species. PCR can detect intestinal parasites more accurately but is generally not feasible in resource-poor settings, at least not in peripheral labs. Hence

Diagnosing Polyparasitism in a High-Prevalence Setting in Beira, Mozambique: Detection of Intestinal Parasites in Fecal Samples by Microscopy and Real-Time PCR.

Science.gov (United States)

Meurs, Lynn; Polderman, Anton M; Vinkeles Melchers, Natalie V S; Brienen, Eric A T; Verweij, Jaco J; Groosjohan, Bernhard; Mendes, Felisberto; Mechendura, Manito; Hepp, Dagmar H; Langenberg, Marijke C C; Edelenbosch, Rosanne; Polman, Katja; van Lieshout, Lisette

2017-01-01

Many different intestinal parasite species can co-occur in the same population. However, classic diagnostic tools can only frame a particular group of intestinal parasite species. Hence, one or two tests do not suffice to provide a complete picture of infecting parasite species in a given population. The present study investigated intestinal parasitic infections in Beira, Mozambique, i.e. in the informal settlement of Inhamudima. Diagnostic accuracy of five classical microscopy techniques and real-time PCR for the detection of a broad spectrum of parasites was compared. A cross-sectional population-based survey was performed. One stool sample per participant (n = 303) was examined by direct smear, formal-ether concentration (FEC), Kato smear, Baermann method, coproculture and real-time PCR. We found that virtually all people (96%) harbored at least one helminth, and that almost half (49%) harbored three helminths or more. Remarkably, Strongyloides stercoralis infections were widespread with a prevalence of 48%, and Ancylostoma spp. prevalence was higher than that of Necator americanus (25% versus 15%), the hookworm species that is often assumed to prevail in East-Africa. Among the microscopic techniques, FEC was able to detect the broadest spectrum of parasite species. However, FEC also missed a considerable number of infections, notably S. stercoralis, Schistosoma mansoni and G. intestinalis. PCR outperformed microscopy in terms of sensitivity and range of parasite species detected. We showed intestinal parasites-especially helminths-to be omnipresent in Inhamudima, Beira. However, it is a challenge to achieve high diagnostic sensitivity for all species. Classical techniques such as FEC are useful for the detection of some intestinal helminth species, but they lack sensitivity for other parasite species. PCR can detect intestinal parasites more accurately but is generally not feasible in resource-poor settings, at least not in peripheral labs. Hence, there is a

Northeast India Helminth Parasite Information Database (NEIHPID: Knowledge Base for Helminth Parasites.

Directory of Open Access Journals (Sweden)

Devendra Kumar Biswal

Full Text Available Most metazoan parasites that invade vertebrate hosts belong to three phyla: Platyhelminthes, Nematoda and Acanthocephala. Many of the parasitic members of these phyla are collectively known as helminths and are causative agents of many debilitating, deforming and lethal diseases of humans and animals. The North-East India Helminth Parasite Information Database (NEIHPID project aimed to document and characterise the spectrum of helminth parasites in the north-eastern region of India, providing host, geographical distribution, diagnostic characters and image data. The morphology-based taxonomic data are supplemented with information on DNA sequences of nuclear, ribosomal and mitochondrial gene marker regions that aid in parasite identification. In addition, the database contains raw next generation sequencing (NGS data for 3 foodborne trematode parasites, with more to follow. The database will also provide study material for students interested in parasite biology. Users can search the database at various taxonomic levels (phylum, class, order, superfamily, family, genus, and species, or by host, habitat and geographical location. Specimen collection locations are noted as co-ordinates in a MySQL database and can be viewed on Google maps, using Google Maps JavaScript API v3. The NEIHPID database has been made freely available at http://nepiac.nehu.ac.in/index.php.

Northeast India Helminth Parasite Information Database (NEIHPID): Knowledge Base for Helminth Parasites.

Science.gov (United States)

Biswal, Devendra Kumar; Debnath, Manish; Kharumnuid, Graciously; Thongnibah, Welfrank; Tandon, Veena

2016-01-01

Most metazoan parasites that invade vertebrate hosts belong to three phyla: Platyhelminthes, Nematoda and Acanthocephala. Many of the parasitic members of these phyla are collectively known as helminths and are causative agents of many debilitating, deforming and lethal diseases of humans and animals. The North-East India Helminth Parasite Information Database (NEIHPID) project aimed to document and characterise the spectrum of helminth parasites in the north-eastern region of India, providing host, geographical distribution, diagnostic characters and image data. The morphology-based taxonomic data are supplemented with information on DNA sequences of nuclear, ribosomal and mitochondrial gene marker regions that aid in parasite identification. In addition, the database contains raw next generation sequencing (NGS) data for 3 foodborne trematode parasites, with more to follow. The database will also provide study material for students interested in parasite biology. Users can search the database at various taxonomic levels (phylum, class, order, superfamily, family, genus, and species), or by host, habitat and geographical location. Specimen collection locations are noted as co-ordinates in a MySQL database and can be viewed on Google maps, using Google Maps JavaScript API v3. The NEIHPID database has been made freely available at http://nepiac.nehu.ac.in/index.php.

Northeast India Helminth Parasite Information Database (NEIHPID): Knowledge Base for Helminth Parasites

Science.gov (United States)

Debnath, Manish; Kharumnuid, Graciously; Thongnibah, Welfrank; Tandon, Veena

2016-01-01

Most metazoan parasites that invade vertebrate hosts belong to three phyla: Platyhelminthes, Nematoda and Acanthocephala. Many of the parasitic members of these phyla are collectively known as helminths and are causative agents of many debilitating, deforming and lethal diseases of humans and animals. The North-East India Helminth Parasite Information Database (NEIHPID) project aimed to document and characterise the spectrum of helminth parasites in the north-eastern region of India, providing host, geographical distribution, diagnostic characters and image data. The morphology-based taxonomic data are supplemented with information on DNA sequences of nuclear, ribosomal and mitochondrial gene marker regions that aid in parasite identification. In addition, the database contains raw next generation sequencing (NGS) data for 3 foodborne trematode parasites, with more to follow. The database will also provide study material for students interested in parasite biology. Users can search the database at various taxonomic levels (phylum, class, order, superfamily, family, genus, and species), or by host, habitat and geographical location. Specimen collection locations are noted as co-ordinates in a MySQL database and can be viewed on Google maps, using Google Maps JavaScript API v3. The NEIHPID database has been made freely available at http://nepiac.nehu.ac.in/index.php PMID:27285615

Density-dependent phonoriton states in highly excited semiconductors

International Nuclear Information System (INIS)

Nguyen Hong Quang; Nguyen Minh Khue; Nguyen Que Huong

1995-09-01

The dynamical aspects of the phonoriton state in highly-photoexcited semiconductors is studied theoretically. The effect of the exciton-exciton interaction and nonbosonic character of high-density excitons are taken into account. Using Green's function method and within the Random Phase Approximation it is shown that the phonoriton dispersion and damping are very sensitive to the exciton density, characterizing the excitation degree of semiconductors. (author). 18 refs, 3 figs

Parasitic fauna in hybrid tambacu from fish farms

Directory of Open Access Journals (Sweden)

Ronilson Macedo Silva

2013-08-01

Full Text Available The objective of this work was to evaluate the parasitic fauna of hybrid tambacu (Colossoma macropomum x Piaractus mesopotamicus from fish farms and the host-parasite relationship. A hundred and fourteen fish were collected from four fish farms in Macapá, in the state of Amapá, Brazil, 80.7% of which were infected by: Ichthyophthirius multifiliis (Ciliophora; Piscinoodinium pillulare (Dinoflagellida; Anacanthorus spatulatus, Notozothecium janauachensis, and Mymarothecium viatorum (Monogenoidea; Neoechinorhynchus buttnerae (Acanthocephala; Cucullanus colossomi (Nematoda; Perulernaea gamitanae (Lernaeidae; and Proteocephalidae larvae (Cestoda. A total of 8,136,252 parasites were collected from the examined fish. This is the first record of N. buttnerae, C. colossomi, N. janauachensis, M. viatorum, and Proteocephalidae for hybrid tambacu in Brazil. Ichthyophthirius multifiliis was the most prevalent parasite, whereas endohelminths were the less. A positive correlation was observed between number of I. multifiliis and total length and weight of fish, as well as between number of P. gamitanae and total length. The infection by I. multifiliis had association with the parasitism by Monogenoidea. Low water quality contributes to high parasitism of hybrid tambacu by ectoparasites, which, however, does not influence the relative condition factor of fish.

Prevalence of gastrointestinal parasites in domestic dogs in Tabasco, southeastern Mexico

Directory of Open Access Journals (Sweden)

Oswaldo Margarito Torres-Chablé

Full Text Available Abstract The overall goal of this study was to estimate the prevalence of gastrointestinal (GI parasites in dogs in the city of Villahermosa in Tabasco, Mexico. The study population consisted of 302 owned dogs that had limited access to public areas. A fecal sample was collected from each animal and examined for GI parasites by conventional macroscopic analysis and centrifugal flotation. Fecal samples from 80 (26.5% dogs contained GI parasites. Of these, 58 (19.2% were positive for helminths and 22 (7.3% were positive for protozoan parasites. At least seven parasitic species were identified. The most common parasite was Ancylostoma caninum which was detected in 48 (15.9% dogs. Other parasites detected on multiple occasions were Cystoisospora spp. (n = 19, Toxocara canis (n = 7 and Giardia spp. (n = 3. Three additional parasites, Dipylidium caninum, Trichuris vulpis and Uncinaria spp., were each detected in a single dog. No mixed parasitic infections were identified. In summary, we report a moderately high prevalence of GI parasites in owned dogs in Villahermosa, Tabasco. Several parasitic species identified in this study are recognized zoonotic pathogens which illustrates the important need to routinely monitor and treat dogs that live in close proximity to humans for parasitic infections.

Probability of Transmission of Malaria from Mosquito to Human Is Regulated by Mosquito Parasite Density in Naïve and Vaccinated Hosts.

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Thomas S Churcher

2017-01-01

Full Text Available Over a century since Ronald Ross discovered that malaria is caused by the bite of an infectious mosquito it is still unclear how the number of parasites injected influences disease transmission. Currently it is assumed that all mosquitoes with salivary gland sporozoites are equally infectious irrespective of the number of parasites they harbour, though this has never been rigorously tested. Here we analyse >1000 experimental infections of humans and mice and demonstrate a dose-dependency for probability of infection and the length of the host pre-patent period. Mosquitoes with a higher numbers of sporozoites in their salivary glands following blood-feeding are more likely to have caused infection (and have done so quicker than mosquitoes with fewer parasites. A similar dose response for the probability of infection was seen for humans given a pre-erythrocytic vaccine candidate targeting circumsporozoite protein (CSP, and in mice with and without transfusion of anti-CSP antibodies. These interventions prevented infection more efficiently from bites made by mosquitoes with fewer parasites. The importance of parasite number has widespread implications across malariology, ranging from our basic understanding of the parasite, how vaccines are evaluated and the way in which transmission should be measured in the field. It also provides direct evidence for why the only registered malaria vaccine RTS,S was partially effective in recent clinical trials.

Productivity and fishing pressure drive variability in fish parasite assemblages of the Line Islands, equatorial Pacific.

Science.gov (United States)

Wood, Chelsea L; Baum, Julia K; Reddy, Sheila M W; Trebilco, Rowan; Sandin, Stuart A; Zgliczynski, Brian J; Briggs, Amy A; Micheli, Fiorenza

2015-05-01

Variability in primary productivity and fishing pressure can shape the abundance, species composition, and diversity of marine life. Though parasites comprise nearly half of marine species, their responses to these important forces remain little explored. We quantified parasite assemblages at two spatial scales, across a gradient in productivity and fishing pressure that spans six coral islands of the Line Islands archipelago and within the largest Line Island, Kiritimati, which experiences a west-to-east gradient in fishing pressure and upwelling-driven productivity. In the across-islands data set, we found that increasing productivity was correlated with increased parasite abundance overall, but that the effects of productivity differed among parasite groups. Trophically transmitted parasites increased in abundance with increasing productivity, but directly transmitted parasites did not exhibit significant changes. This probably arises because productivity has stronger effects on the abundance of the planktonic crustaceans and herbivorous snails that serve as the intermediate hosts of trophically transmitted parasites than on the higher-trophic level fishes that are the sole hosts of directly transmitted parasites. We also found that specialist parasites increased in response to increasing productivity, while generalists did not, possibly because specialist parasites tend to be more strongly limited by host availability than are generalist parasites. After the effect of productivity was controlled for, fishing was correlated with decreases in the abundance of trophically transmitted parasites, while directly transmitted parasites appeared to track host density; we observed increases in the abundance of parasites using hosts that experienced fishing-driven compensatory increases in abundance. The within-island data set confirmed these patterns for the combined effects of productivity and fishing on parasite abundance, suggesting that our conclusions are robust

Isolation of intracellular parasites (Plasmodium falciparum) from culture using free-flow electrophoresis: separation of the free parasites according to stages.

Science.gov (United States)

Heidrich, H G; Mrema, J E; Vander Jagt, D L; Reyes, P; Rieckmann, K H

1982-06-01

Parasitized human erythrocytes were concentrated from continuous cultures of Plasmodium falciparum from 5-7% up to 80-95% using Plasmagel. After aggregation of the cells with phythemagglutinin, the aggregated erythrocytes were fragmented by passing them, with minimal force, through successive nylon filters of decreasing pore size (100 microns-3 microns). The mixture of liberated, free parasites, intact erythrocytes and erythrocyte membrane vesicles was separated using free-flow electrophoresis. Most of the fractions containing free parasites did not show contamination with erythrocyte constituents as determined by light and electron microscopy, polyacrylamide gel electrophoresis, and enzymatic analysis. In addition, the various stages of free parasites of Plasmodium falciparum exhibited different electrical surface charges. Rings and trophozoites were highly negatively charged whereas schizonts and, in particular, merozoites showed low negative charges. Thus, the various stages could be isolated separate from each other.

Multiplexed, high density electrophysiology with nanofabricated neural probes.

Directory of Open Access Journals (Sweden)

Jiangang Du

Full Text Available Extracellular electrode arrays can reveal the neuronal network correlates of behavior with single-cell, single-spike, and sub-millisecond resolution. However, implantable electrodes are inherently invasive, and efforts to scale up the number and density of recording sites must compromise on device size in order to connect the electrodes. Here, we report on silicon-based neural probes employing nanofabricated, high-density electrical leads. Furthermore, we address the challenge of reading out multichannel data with an application-specific integrated circuit (ASIC performing signal amplification, band-pass filtering, and multiplexing functions. We demonstrate high spatial resolution extracellular measurements with a fully integrated, low noise 64-channel system weighing just 330 mg. The on-chip multiplexers make possible recordings with substantially fewer external wires than the number of input channels. By combining nanofabricated probes with ASICs we have implemented a system for performing large-scale, high-density electrophysiology in small, freely behaving animals that is both minimally invasive and highly scalable.

Not all are free-living: high-throughput DNA metabarcoding reveals a diverse community of protists parasitizing soil metazoa

NARCIS (Netherlands)

Geisen, S.; Laros, I.; Vizcaino, A.; Bonkowski, M.; Groot, de G.A.

2015-01-01

Protists, the most diverse eukaryotes, are largely considered to be free-living bacterivores, but vast numbers of taxa are known to parasitize plants or animals. High-throughput sequencing (HTS) approaches now commonly replace cultivation-based approaches in studying soil protists, but insights into

Double trouble at high density:

DEFF Research Database (Denmark)

Gergs, André; Palmqvist, Annemette; Preuss, Thomas G

2014-01-01

Population size is often regulated by negative feedback between population density and individual fitness. At high population densities, animals run into double trouble: they might concurrently suffer from overexploitation of resources and also from negative interference among individuals...... regardless of resource availability, referred to as crowding. Animals are able to adapt to resource shortages by exhibiting a repertoire of life history and physiological plasticities. In addition to resource-related plasticity, crowding might lead to reduced fitness, with consequences for individual life...... history. We explored how different mechanisms behind resource-related plasticity and crowding-related fitness act independently or together, using the water flea Daphnia magna as a case study. For testing hypotheses related to mechanisms of plasticity and crowding stress across different biological levels...

Haematological and histopathological analysis in South American fish Piaractus mesopotamicus parasitized by monogenean (Dactylogyridae

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GT Jerônimo

Full Text Available Monogeneans are the parasites mostly found on the body surface and gills of fish and can cause large losses in farmed fish. Some studies demonstrate elevated parasitic levels causing hematological alterations. But few of them relate the effects of parasitism on the hematology and histopathology of native freshwater farmed fish. This study evaluated the host-parasite relationship in pacu (Piaractus mesopotamicus parasitized by the monogenean Anacanthorus penilabiatus. Hematological and parasitological assessments were obtained in 60 fish captured in a fish farm located in Dourados, State of Mato Grosso do Sul, Central Brazil. Fish were analyzed in different categories of parasite number: class I (n=13; 0-200 parasites, class II (n=17; 201-1200 parasites; class III (n=7; 1201-2200 parasites; and class IV (n=23; more than 2200 parasites per host. The highest levels of parasitism caused significant decrease (p<0.05 in the hematocrit, red blood cells (RBC, mean hemoglobin concentration (MCHC and basophils number. Thrombocytes, mean corpuscular volume (MCV, mean corpuscular hemoglobin concentration (MCHC, monocytes, eosinophils, neutrophils and LG-PAS did not present significant difference among the parasitic levels. In contrast, increased number of total leukocytes and lymphocytes were found in highly-parasitized fish. A positive linear correlation (p<0.01 was found between the amount of parasites and fish weight. Histopathology revealed severe hyperplasia, sub-epithelial edema, fusion of the secondary lamellae, focal and multifocal necrosis in highly parasitized fish.

Parasites as Biological Tags for Stock Discrimination of Beaked Redfish (Sebastes mentella: Parasite Infra-Communities vs. Limited Resolution of Cytochrome Markers.

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Regina Klapper

Full Text Available The use of parasites as biological tags for discrimination of fish stocks has become a commonly used approach in fisheries management. Metazoan parasite community analysis and anisakid nematode population genetics based on a mitochondrial cytochrome marker were applied in order to assess the usefulness of the two parasitological methods for stock discrimination of beaked redfish Sebastes mentella of three fishing grounds in the North East Atlantic. Multivariate, model-based approaches demonstrated that the metazoan parasite fauna of beaked redfish from East Greenland differed from Tampen, northern North Sea, and Bear Island, Barents Sea. A joint model (latent variable model was used to estimate the effects of covariates on parasite species and identified four parasite species as main source of differences among fishing grounds; namely Chondracanthus nodosus, Anisakis simplex s.s., Hysterothylacium aduncum, and Bothriocephalus scorpii. Due to its high abundance and differences between fishing grounds, Anisakis simplex s.s. was considered as a major biological tag for host stock differentiation. Whilst the sole examination of Anisakis simplex s.s. on a population genetic level is only of limited use, anisakid nematodes (in particular, A. simplex s.s. can serve as biological tags on a parasite community level. This study confirmed the use of multivariate analyses as a tool to evaluate parasite infra-communities and to identify parasite species that might serve as biological tags. The present study suggests that S. mentella in the northern North Sea and Barents Sea is not sub-structured.

High density data storage principle, technology, and materials

CERN Document Server

Zhu, Daoben

2009-01-01

The explosive increase in information and the miniaturization of electronic devices demand new recording technologies and materials that combine high density, fast response, long retention time and rewriting capability. As predicted, the current silicon-based computer circuits are reaching their physical limits. Further miniaturization of the electronic components and increase in data storage density are vital for the next generation of IT equipment such as ultra high-speed mobile computing, communication devices and sophisticated sensors. This original book presents a comprehensive introduction to the significant research achievements on high-density data storage from the aspects of recording mechanisms, materials and fabrication technologies, which are promising for overcoming the physical limits of current data storage systems. The book serves as an useful guide for the development of optimized materials, technologies and device structures for future information storage, and will lead readers to the fascin...

Energetic cost of bot fly parasitism in free-ranging eastern chipmunks.

Science.gov (United States)

Careau, Vincent; Thomas, Donald W; Humphries, Murray M

2010-02-01

The energy and nutrient demands of parasites on their hosts are frequently invoked as an explanation for negative impacts of parasitism on host survival and reproductive success. Although cuterebrid bot flies are among the physically largest and most-studied insect parasites of mammals, the only study conducted on metabolic consequences of bot fly parasitism revealed a surprisingly small effect of bot flies on host metabolism. Here we test the prediction that bot fly parasitism increases the resting metabolic rate (RMR) of free-ranging eastern chipmunks (Tamias striatus), particularly in juveniles who have not previously encountered parasites and have to allocate energy to growth. We found no effect of bot fly parasitism on adults. In juveniles, however, we found that RMR strongly increased with the number of bot fly larvae hosted. For a subset of 12 juveniles during a year where parasite prevalence was particularly high, we also compared the RMR before versus during the peak of bot fly prevalence, allowing each individual to act as its own control. Each bot fly larva resulted in a approximately 7.6% increase in the RMR of its host while reducing juvenile growth rates. Finally, bot fly parasitism at the juvenile stage was positively correlated with adult stage RMR, suggesting persistent effects of bot flies on RMR. This study is the first to show an important effect of bot fly parasitism on the metabolism and growth of a wild mammal. Our work highlights the importance of studying cost of parasitism over multiple years in natural settings, as negative effects on hosts are more likely to emerge in periods of high energetic demand (e.g. growing juveniles) and/or in harsh environmental conditions (e.g. low food availability).

Regulation of Gene Expression in Protozoa Parasites

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Consuelo Gomez

2010-01-01

Full Text Available Infections with protozoa parasites are associated with high burdens of morbidity and mortality across the developing world. Despite extensive efforts to control the transmission of these parasites, the spread of populations resistant to drugs and the lack of effective vaccines against them contribute to their persistence as major public health problems. Parasites should perform a strict control on the expression of genes involved in their pathogenicity, differentiation, immune evasion, or drug resistance, and the comprehension of the mechanisms implicated in that control could help to develop novel therapeutic strategies. However, until now these mechanisms are poorly understood in protozoa. Recent investigations into gene expression in protozoa parasites suggest that they possess many of the canonical machineries employed by higher eukaryotes for the control of gene expression at transcriptional, posttranscriptional, and epigenetic levels, but they also contain exclusive mechanisms. Here, we review the current understanding about the regulation of gene expression in Plasmodium sp., Trypanosomatids, Entamoeba histolytica and Trichomonas vaginalis.

Regulation of gene expression in protozoa parasites.

Science.gov (United States)

Gomez, Consuelo; Esther Ramirez, M; Calixto-Galvez, Mercedes; Medel, Olivia; Rodríguez, Mario A

2010-01-01

Infections with protozoa parasites are associated with high burdens of morbidity and mortality across the developing world. Despite extensive efforts to control the transmission of these parasites, the spread of populations resistant to drugs and the lack of effective vaccines against them contribute to their persistence as major public health problems. Parasites should perform a strict control on the expression of genes involved in their pathogenicity, differentiation, immune evasion, or drug resistance, and the comprehension of the mechanisms implicated in that control could help to develop novel therapeutic strategies. However, until now these mechanisms are poorly understood in protozoa. Recent investigations into gene expression in protozoa parasites suggest that they possess many of the canonical machineries employed by higher eukaryotes for the control of gene expression at transcriptional, posttranscriptional, and epigenetic levels, but they also contain exclusive mechanisms. Here, we review the current understanding about the regulation of gene expression in Plasmodium sp., Trypanosomatids, Entamoeba histolytica and Trichomonas vaginalis.

High levels of prevalence related to age and body condition: host-parasite interactions in a water frog Pelophylax kl hispanicus

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Mar Comas

2014-06-01

Full Text Available Host traits can significantly influence patterns of infection and disease. Here, we studied the helminths parasitizing the Italian edible frog Pelophylax kl. hispanicus, giving special attention to the relationship between parasites and host traits such as sex, snout vent length, weight and body condition. The helminth community was composed of seven species: three trematode species (Diplodiscus subclavatus, Gorgodera cygnoides, Pleurogenes claviger, three nematode species (Icosiella neglecta, Oswaldocruzia filiformis, Rhabdias sp. and one acanthocephalan species (Pomphorhychus laevis. We found that prevalence was positively correlated with snout-vent length and weight, but did not differ with body condition or sex. We found that prevalence and mean species richness increased with age. Our results show that abundance of Icosiella neglecta was positively correlated with higher values for host body condition. In fact, we found that high prevalence and mean species richness do not necessarily imply poorer body condition in the parasitized host. In conclusion, our results show that the helminth community in this taxon has great diversity, and this host-parasite system seems to be evolved to low levels of virulence, helminths maintaining a commensal relationship with this frog.

Fifth International Conference on High Energy Density Physics

Energy Technology Data Exchange (ETDEWEB)

Beg, Farhat

2017-07-05

The Fifth International Conference on High Energy Density Physics (ICHED 2015) was held in the Catamaran Hotel in San Diego from August 23-27, 2015. This meeting was the fifth in a series which began in 2008 in conjunction with the April meeting of the American Physical Society (APS). The main goal of this conference has been to bring together researchers from all fields of High Energy Density Science (HEDS) into one, unified meeting.

Parasites of importance for human health in Nigerian dogs: high prevalence and limited knowledge of pet owners

Directory of Open Access Journals (Sweden)

Heukelbach Jorg

2008-12-01

Full Text Available Abstract Background Dogs are the most common pet animals worldwide. They may harbour a wide range of parasites with zoonotic potential, thus causing a health risk to humans. In Nigeria, epidemiological knowledge on these parasites is limited. Methods In a community-based study, we examined 396 dogs in urban and rural areas of Ilorin (Kwara State, Central Nigeria for ectoparasites and intestinal helminths. In addition, a questionnaire regarding knowledge and practices was applied to pet owners. Results Nine ectoparasite species belonging to four taxa and six intestinal helminth species were identified: fleas (Ctenocephalides canis, Pulex irritans, Tunga penetrans, mites (Demodex canis, Otodectes sp., Sarcoptes scabiei var. canis, ticks (Rhipicephalus sanguineus, Ixodes sp., and lice (Trichodectes canis; and Toxocara canis, Ancylostoma sp., Trichuris vulpis, Dipylidium caninum, Taenidae and Strongyloides sp. Overall prevalence of ectoparasites was 60.4% and of intestinal helminths 68.4%. The occurrence of C. canis, R. sanguineus, T. canis, Ancylostoma sp. and T. vulpis was most common (prevalence 14.4% to 41.7%. Prevalence patterns in helminths were age-dependent, with T. canis showing a decreasing prevalence with age of host, and a reverse trend in other parasite species. Knowledge regarding zoonoses was very limited and the diseases not considered a major health problem. Treatment with antiparasitic drugs was more frequent in urban areas. Conclusion Parasites of importance for human health were highly prevalent in Nigerian dogs. Interventions should include health education provided to dog owners and the establishment of a program focusing on zoonotic diseases.

High performance H-mode plasmas at densities above the Greenwald limit

International Nuclear Information System (INIS)

Mahdavi, M.A.; Osborne, T.H.; Leonard, A.W.

2001-01-01

Densities up to 40 percent above the Greenwald limit are reproducibly achieved in high confinement (H ITER89p =2) ELMing H-mode discharges. Simultaneous gas fueling and divertor pumping were used to obtain these results. Confinement of these discharges, similar to moderate density H-mode, is characterized by a stiff temperature profile, and therefore sensitive to the density profile. A particle transport model is presented that explains the roles of divertor pumping and geometry for access to high densities. Energy loss per ELM at high density is a factor of five lower than predictions of an earlier scaling, based on data from lower density discharges. (author)

Novel nanostructured materials for high energy density supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Yuan, C.Z.; Zhang, X.G. [Nanjing Univ. of Aeronautics and Astronautics (China). College of Material Science and Engineering

2010-07-01

Researchers are currently examining methods of improving energy density while not sacrificing the high power density of supercapacitors. In this study, nanostructured materials assembled from nanometer-sized building blocks with mesoporosity were synthesized in order investigate diffusion time, kinetics, and capacitances. Petal-like cobalt hydroxide Co(OH){sub 2} mesocrystals, urchin-like Co(OH){sub 2} and dicobalt tetroxide (Co{sub 2}O{sub 4}) ordered arrays as well as N{sub i}O microspheres were assembled from 0-D nanoparticles, 1-D mesoporous nanowires and nanobelts, and 2-D mesoporous nanopetals. The study showed that all the synthesized nanostructured materials delivered larger energy densities while showing electrochemical stability at high rates.

ON THE ORIGIN OF THE HIGH COLUMN DENSITY TURNOVER IN THE H I COLUMN DENSITY DISTRIBUTION

International Nuclear Information System (INIS)

Erkal, Denis; Gnedin, Nickolay Y.; Kravtsov, Andrey V.

2012-01-01

We study the high column density regime of the H I column density distribution function and argue that there are two distinct features: a turnover at N H I ≈ 10 21 cm –2 , which is present at both z = 0 and z ≈ 3, and a lack of systems above N H I ≈ 10 22 cm –2 at z = 0. Using observations of the column density distribution, we argue that the H I-H 2 transition does not cause the turnover at N H I ≈ 10 21 cm –2 but can plausibly explain the turnover at N H I ∼> 10 22 cm –2 . We compute the H I column density distribution of individual galaxies in the THINGS sample and show that the turnover column density depends only weakly on metallicity. Furthermore, we show that the column density distribution of galaxies, corrected for inclination, is insensitive to the resolution of the H I map or to averaging in radial shells. Our results indicate that the similarity of H I column density distributions at z = 3 and 0 is due to the similarity of the maximum H I surface densities of high-z and low-z disks, set presumably by universal processes that shape properties of the gaseous disks of galaxies. Using fully cosmological simulations, we explore other candidate physical mechanisms that could produce a turnover in the column density distribution. We show that while turbulence within giant molecular clouds cannot affect the damped Lyα column density distribution, stellar feedback can affect it significantly if the feedback is sufficiently effective in removing gas from the central 2-3 kpc of high-redshift galaxies. Finally, we argue that it is meaningful to compare column densities averaged over ∼ kpc scales with those estimated from quasar spectra that probe sub-pc scales due to the steep power spectrum of H I column density fluctuations observed in nearby galaxies.

Fish parasites

DEFF Research Database (Denmark)

This book contains 22 chapters on some of the most important parasitic diseases in wild and farmed fish. International experts give updated reviews and provide solutions to the problems......This book contains 22 chapters on some of the most important parasitic diseases in wild and farmed fish. International experts give updated reviews and provide solutions to the problems...

Multi-Level Determinants of Parasitic Fly Infection in Forest Passerines

Science.gov (United States)

Manzoli, Darío Ezequiel; Antoniazzi, Leandro Raúl; Saravia, María José; Silvestri, Leonardo; Rorhmann, David; Beldomenico, Pablo Martín

2013-01-01

The study of myiasis is important because they may cause problems to the livestock industry, public health, or wildlife conservation. The ecology of parasitic dipterans that cause myiasis is singular, as they actively seek their hosts over relatively long distances. However, studies that address the determinants of myiasis dynamics are very scarce. The genus Philornis include species that may be excellent models to study myiasis ecology, as they exclusively parasitize bird nestlings, which stay in their nests until they are fully fledged, and larvae remain at the point of entry until the parasitic stage is over, thus allowing the collection of sequential individual-level infection data from virtually all the hosts present at a particular area. Here we offer a stratified multi-level analysis of longitudinal data of Philornis torquans parasitism in replicated forest bird communities of central Argentina. Using Generalized Linear Models and Generalized Linear Mixed Models and an information theory approach for model selection, we conducted four groups of analyses, each with a different study unit, the individual, the brood, the community at a given week, and the community at a given year. The response variable was larval abundance per nestling or mean abundance per nestling. At each level, models included the variables of interest of that particular level, and also potential confounders and effect modifiers of higher levels. We found associations of large magnitude at all levels, but only few variables truly governed the dynamics of this parasite. At the individual level, the infection was determined by the species and the age of the host. The main driver of parasite abundance at the microhabitat level was the average height of the forest, and at the community level, the density of hosts and prior rainfall. This multi-level approach contributed to a better understanding of the ecology of myiasis. PMID:23874408

Changes to cholesterol trafficking in macrophages by Leishmania parasites infection.

Science.gov (United States)

Semini, Geo; Paape, Daniel; Paterou, Athina; Schroeder, Juliane; Barrios-Llerena, Martin; Aebischer, Toni

2017-08-01

Leishmania spp. are protozoan parasites that are transmitted by sandfly vectors during blood sucking to vertebrate hosts and cause a spectrum of diseases called leishmaniases. It has been demonstrated that host cholesterol plays an important role during Leishmania infection. Nevertheless, little is known about the intracellular distribution of this lipid early after internalization of the parasite. Here, pulse-chase experiments with radiolabeled cholesteryl esterified to fatty acids bound to low-density lipoproteins indicated that retention of this source of cholesterol is increased in parasite-containing subcellular fractions, while uptake is unaffected. This is correlated with a reduction or absence of detectable NPC1 (Niemann-Pick disease, type C1), a protein responsible for cholesterol efflux from endocytic compartments, in the Leishmania mexicana habitat and infected cells. Filipin staining revealed a halo around parasites within parasitophorous vacuoles (PV) likely representing free cholesterol accumulation. Labeling of host cell membranous cholesterol by fluorescent cholesterol species before infection revealed that this pool is also trafficked to the PV but becomes incorporated into the parasites' membranes and seems not to contribute to the halo detected by filipin. This cholesterol sequestration happened early after infection and was functionally significant as it correlated with the upregulation of mRNA-encoding proteins required for cholesterol biosynthesis. Thus, sequestration of cholesterol by Leishmania amastigotes early after infection provides a basis to understand perturbation of cholesterol-dependent processes in macrophages that were shown previously by others to be necessary for their proper function in innate and adaptive immune responses. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Malaria parasites: the great escape

Directory of Open Access Journals (Sweden)

Laurent Rénia

2016-11-01

Full Text Available Parasites of the genus Plasmodium have a complex life cycle. They alternate between their final mosquito host and their intermediate hosts. The parasite can be either extra- or intracellular, depending on the stage of development. By modifying their shape, motility, and metabolic requirements, the parasite adapts to the different environments in their different hosts. The parasite has evolved to escape the multiple immune mechanisms in the host that try to block parasite development at the different stages of their development. In this article, we describe the mechanisms reported thus far that allow the Plasmodium parasite to evade innate and adaptive immune responses.

Effect of mix proportion of high density concrete on compressive strength, density and radiation absorption

International Nuclear Information System (INIS)

Noor Azreen Masenwat; Mohamad Pauzi Ismail; Suhairy Sani; Ismail Mustapha; Nasharuddin Isa; Mohamad Haniza Mahmud; Mohammad Shahrizan Samsu

2014-01-01

To prevent radiation leaks at nuclear reactors, high-density concrete is used as an absorbent material for radiation from spreading into the environment. High-density concrete is a mixture of cement, sand, aggregate (usually high-density minerals) and water. In this research, hematite stone is used because of its mineral density higher than the granite used in conventional concrete mixing. Mix concrete in this study were divided into part 1 and part 2. In part 1, the concrete mixture is designed with the same ratio of 1: 2: 4 but differentiated in terms of water-cement ratio (0.60, 0.65, 0.70, 0.75, 0.80 ). Whereas, in part 2, the concrete mixture is designed to vary the ratio of 1: 1: 2, 1: 1.5: 3, 1: 2: 3, 1: 3: 6, 1: 2: 6 with water-cement ratio (0.7, 0.8, 0.85, 0.9). In each section, the division has also performed in a mixture of sand and fine sand hematite. Then, the physical characteristics of the density and the compressive strength of the mixture of part 1 and part 2 is measured. Comparisons were also made in terms of absorption of radiation by Cs-137 and Co-60 source for each mix. This paper describes and discusses the relationship between the concrete mixture ratio, the relationship with the water-cement ratio, compressive strength, density, different mixture of sand and fine sand hematite. (author)

A novel high throughput assay for anthelmintic drug screening and resistance diagnosis by real-time monitoring of parasite motility.

Directory of Open Access Journals (Sweden)

Michael J Smout

Full Text Available BACKGROUND: Helminth parasites cause untold morbidity and mortality to billions of people and livestock. Anthelmintic drugs are available but resistance is a problem in livestock parasites, and is a looming threat for human helminths. Testing the efficacy of available anthelmintic drugs and development of new drugs is hindered by the lack of objective high-throughput screening methods. Currently, drug effect is assessed by observing motility or development of parasites using laborious, subjective, low-throughput methods. METHODOLOGY/PRINCIPAL FINDINGS: Here we describe a novel application for a real-time cell monitoring device (xCELLigence that can simply and objectively assess anthelmintic effects by measuring parasite motility in real time in a fully automated high-throughput fashion. We quantitatively assessed motility and determined real time IC(50 values of different anthelmintic drugs against several developmental stages of major helminth pathogens of humans and livestock, including larval Haemonchus contortus and Strongyloides ratti, and adult hookworms and blood flukes. The assay enabled quantification of the onset of egg hatching in real time, and the impact of drugs on hatch rate, as well as discriminating between the effects of drugs on motility of drug-susceptible and -resistant isolates of H. contortus. CONCLUSIONS/SIGNIFICANCE: Our findings indicate that this technique will be suitable for discovery and development of new anthelmintic drugs as well as for detection of phenotypic resistance to existing drugs for the majority of helminths and other pathogens where motility is a measure of pathogen viability. The method is also amenable to use for other purposes where motility is assessed, such as gene silencing or antibody-mediated killing.

Chagas Parasite Detection in Blood Images Using AdaBoost

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Víctor Uc-Cetina

2015-01-01

Full Text Available The Chagas disease is a potentially life-threatening illness caused by the protozoan parasite, Trypanosoma cruzi. Visual detection of such parasite through microscopic inspection is a tedious and time-consuming task. In this paper, we provide an AdaBoost learning solution to the task of Chagas parasite detection in blood images. We give details of the algorithm and our experimental setup. With this method, we get 100% and 93.25% of sensitivity and specificity, respectively. A ROC comparison with the method most commonly used for the detection of malaria parasites based on support vector machines (SVM is also provided. Our experimental work shows mainly two things: (1 Chagas parasites can be detected automatically using machine learning methods with high accuracy and (2 AdaBoost + SVM provides better overall detection performance than AdaBoost or SVMs alone. Such results are the best ones known so far for the problem of automatic detection of Chagas parasites through the use of machine learning, computer vision, and image processing methods.

Paleoparasitology: the origin of human parasites

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Adauto Araujo

2013-09-01

Full Text Available Parasitism is composed by three subsystems: the parasite, the host, and the environment. There are no organisms that cannot be parasitized. The relationship between a parasite and its host species most of the time do not result in damage or disease to the host. However, in a parasitic disease the presence of a given parasite is always necessary, at least in a given moment of the infection. Some parasite species that infect humans were inherited from pre-hominids, and were shared with other phylogenetically close host species, but other parasite species were acquired from the environment as humans evolved. Human migration spread inherited parasites throughout the globe. To recover and trace the origin and evolution of infectious diseases, paleoparasitology was created. Paleoparasitology is the study of parasites in ancient material, which provided new information on the evolution, paleoepidemiology, ecology and phylogenetics of infectious diseases.

Protein moonlighting in parasitic protists.

Science.gov (United States)

Ginger, Michael L

2014-12-01

Reductive evolution during the adaptation to obligate parasitism and expansions of gene families encoding virulence factors are characteristics evident to greater or lesser degrees in all parasitic protists studied to date. Large evolutionary distances separate many parasitic protists from the yeast and animal models upon which classic views of eukaryotic biochemistry are often based. Thus a combination of evolutionary divergence, niche adaptation and reductive evolution means the biochemistry of parasitic protists is often very different from their hosts and to other eukaryotes generally, making parasites intriguing subjects for those interested in the phenomenon of moonlighting proteins. In common with other organisms, the contribution of protein moonlighting to parasite biology is only just emerging, and it is not without controversy. Here, an overview of recently identified moonlighting proteins in parasitic protists is provided, together with discussion of some of the controversies.

High density fuel storage rack

International Nuclear Information System (INIS)

Zezza, L.J.

1980-01-01

High storage density for spent nuclear fuel assemblies in a pool achieved by positioning fuel storage cells of high thermal neutron absorption materials in an upright configuration in a rack. The rack holds the cells at required pitch. Each cell carries an internal fuel assembly support, and most cells are vertically movable in the rack so that they rest on the pool bottom. Pool water circulation through the cells and around the fuel assemblies is permitted by circulation openings at the top and bottom of the cells above and below the fuel assemblies

High Density GEOSAT/GM Altimeter Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The high density Geosat/GM altimeter data south of 30 S have finally arrived. In addition, ERS-1 has completed more than 6 cycles of its 35-day repeat track. These...

[Parasitism in Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) in Citrus orchards in Montenegro, RS, Brazil].

Science.gov (United States)

Jahnke, Simone M; Redaelli, Luiza R; Diefenbach, Lúcia M G

2006-01-01

Phyllocnistis citrella Stainton, the citrus-leafminer, is an important pest of citrus worldwide. Knowledge of natural parasitism levels is fundamental to the establishment of tactics of management and control of this species. This work aimed to evaluate the parasitism in two citrus orchards, one of 'Montenegrina' (Citrus deliciosa Ten.) and the other of 'Murcott' (C. sinensis (L.) Osbeck x C. reticulata Blanco), located in Montenegro, RS. In fortnightly samplings, from July/2001 to June/2003, all leaves containing P. citrella pupae from randomly selected plants were collected and maintained individually until emergence of the parasitoids or the citrus-leafminer. Parasitism was calculated considering the number of emerged parasitoids relative to the total number of emerged individuals. Correlation and linear regression tests were done to evaluate the relationship and the influence of biotic and abiotic factors upon the parasitism index. In both orchards the greatest parasitism percentage was registered on autumn in both years. The total percentage was 36.2% in 'Murcott' and 26.4% in 'Montenegrina' in the first year, and 30.2% and 37.6%, respectively, in the second year. In 'Murcott', this index did not differed between the years (chi2 = 2.06; df = 1; P > 0.05), in 'Montenegrina' the parasitism was significantly higher in the second year (chi2 = 7.36; df = 1; P < 0.05). The correlation and linear regression tests indicated a strong influence, in the parasitism index, of the host populational density registered in the previous 45 and 135 days.

High-Current-Density Vertical-Tunneling Transistors from Graphene/Highly Doped Silicon Heterostructures.

Science.gov (United States)

Liu, Yuan; Sheng, Jiming; Wu, Hao; He, Qiyuan; Cheng, Hung-Chieh; Shakir, Muhammad Imran; Huang, Yu; Duan, Xiangfeng

2016-06-01

Scalable fabrication of vertical-tunneling transistors is presented based on heterostructures formed between graphene, highly doped silicon, and its native oxide. Benefiting from the large density of states of highly doped silicon, the tunneling transistors can deliver a current density over 20 A cm(-2) . This study demonstrates that the interfacial native oxide plays a crucial role in governing the carrier transport in graphene-silicon heterostructures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Disease ecology across soil boundaries: effects of below-ground fungi on above-ground host-parasite interactions.

Science.gov (United States)

Tao, Leiling; Gowler, Camden D; Ahmad, Aamina; Hunter, Mark D; de Roode, Jacobus C

2015-10-22

Host-parasite interactions are subject to strong trait-mediated indirect effects from other species. However, it remains unexplored whether such indirect effects may occur across soil boundaries and connect spatially isolated organisms. Here, we demonstrate that, by changing plant (milkweed Asclepias sp.) traits, arbuscular mycorrhizal fungi (AMF) significantly affect interactions between a herbivore (the monarch butterfly Danaus plexippus) and its protozoan parasite (Ophryocystis elektroscirrha), which represents an interaction across four biological kingdoms. In our experiment, AMF affected parasite virulence, host resistance and host tolerance to the parasite. These effects were dependent on both the density of AMF and the identity of milkweed species: AMF indirectly increased disease in monarchs reared on some species, while alleviating disease in monarchs reared on other species. The species-specificity was driven largely by the effects of AMF on both plant primary (phosphorus) and secondary (cardenolides; toxins in milkweeds) traits. Our study demonstrates that trait-mediated indirect effects in disease ecology are extensive, such that below-ground interactions between AMF and plant roots can alter host-parasite interactions above ground. In general, soil biota may play an underappreciated role in the ecology of many terrestrial host-parasite systems. © 2015 The Author(s).

Disease ecology across soil boundaries: effects of below-ground fungi on above-ground host–parasite interactions

Science.gov (United States)

Tao, Leiling; Gowler, Camden D.; Ahmad, Aamina; Hunter, Mark D.; de Roode, Jacobus C.

2015-01-01

Host–parasite interactions are subject to strong trait-mediated indirect effects from other species. However, it remains unexplored whether such indirect effects may occur across soil boundaries and connect spatially isolated organisms. Here, we demonstrate that, by changing plant (milkweed Asclepias sp.) traits, arbuscular mycorrhizal fungi (AMF) significantly affect interactions between a herbivore (the monarch butterfly Danaus plexippus) and its protozoan parasite (Ophryocystis elektroscirrha), which represents an interaction across four biological kingdoms. In our experiment, AMF affected parasite virulence, host resistance and host tolerance to the parasite. These effects were dependent on both the density of AMF and the identity of milkweed species: AMF indirectly increased disease in monarchs reared on some species, while alleviating disease in monarchs reared on other species. The species-specificity was driven largely by the effects of AMF on both plant primary (phosphorus) and secondary (cardenolides; toxins in milkweeds) traits. Our study demonstrates that trait-mediated indirect effects in disease ecology are extensive, such that below-ground interactions between AMF and plant roots can alter host–parasite interactions above ground. In general, soil biota may play an underappreciated role in the ecology of many terrestrial host–parasite systems. PMID:26468247

Role of parasites in cancer.

Science.gov (United States)

Mandong, B M; Ngbea, J A; Raymond, Vhriterhire

2013-01-01

In areas of parasitic endemicity, the occurrence of cancer that is not frequent may be linked with parasitic infection. Epidemiological correlates between some parasitic infections and cancer is strong, suggesting a strong aetiological association. The common parasites associated with human cancers are schistosomiasis, malaria, liver flukes (Clonorchis sinenses, Opistorchis viverrini). To review the pathology, literature and methods of diagnosis. Literature review from peer reviewed Journals cited in PubMed and local journals. Parasites may serve as promoters of cancer in endemic areas of infection.

The creation of high energy densities with antimatter beams

International Nuclear Information System (INIS)

Gibbs, W.R.; Kruk, J.W.; Rice Univ., Houston, TX

1989-01-01

The use of antiprotons (and antideuterons) for the study of the behavior of nuclear matter at high energy density is considered. It is shown that high temperatures and high energy densities can be achieved for small volumes. Also investigated is the strangeness production in antimatter annihilation. It is found that the high rate of Lambda production seen in a recent experiment is easily understood. The Lambda and K-short rapidity distributions are also reproduced by the model considered. 11 refs., 6 figs

High baryon density from relativistic heavy ion collisions

Energy Technology Data Exchange (ETDEWEB)

Pang, Y.; Kahana, S.H. [Brookhaven National Lab., Upton, NY (United States); Schlagel, T.J. [Brookhaven National Lab., Upton, NY (United States)]|[State Univ. of New York, Stony Brook, NY (United States)

1993-10-01

A quantitative model, based on hadronic physics, is developed and applied to heavy ion collisions at BNL-AGS energies. This model is in excellent agreement with observed particle spectra in heavy ion collisions using Si beams, where baryon densities of three and four times the normal nuclear matter density ({rho}{sub 0}) are reached. For Au on Au collisions, the authors predict the formation of matter at very high densities (up to 10 {rho}{sub 0}).

Serum osteoprotegerin levels and mammographic density among high-risk women.

Science.gov (United States)

Moran, Olivia; Zaman, Tasnim; Eisen, Andrea; Demsky, Rochelle; Blackmore, Kristina; Knight, Julia A; Elser, Christine; Ginsburg, Ophira; Zbuk, Kevin; Yaffe, Martin; Narod, Steven A; Salmena, Leonardo; Kotsopoulos, Joanne

2018-06-01

Mammographic density is a risk factor for breast cancer but the mechanism behind this association is unclear. The receptor activator of nuclear factor κB (RANK)/RANK ligand (RANKL) pathway has been implicated in the development of breast cancer. Given the role of RANK signaling in mammary epithelial cell proliferation, we hypothesized this pathway may also be associated with mammographic density. Osteoprotegerin (OPG), a decoy receptor for RANKL, is known to inhibit RANK signaling. Thus, it is of interest to evaluate whether OPG levels modify breast cancer risk through mammographic density. We quantified serum OPG levels in 57 premenopausal and 43 postmenopausal women using an enzyme-linked immunosorbent assay (ELISA). Cumulus was used to measure percent density, dense area, and non-dense area for each mammographic image. Subjects were classified into high versus low OPG levels based on the median serum OPG level in the entire cohort (115.1 pg/mL). Multivariate models were used to assess the relationship between serum OPG levels and the measures of mammographic density. Serum OPG levels were not associated with mammographic density among premenopausal women (P ≥ 0.42). Among postmenopausal women, those with low serum OPG levels had higher mean percent mammographic density (20.9% vs. 13.7%; P = 0.04) and mean dense area (23.4 cm 2 vs. 15.2 cm 2 ; P = 0.02) compared to those with high serum OPG levels after covariate adjustment. These findings suggest that low OPG levels may be associated with high mammographic density, particularly in postmenopausal women. Targeting RANK signaling may represent a plausible, non-surgical prevention option for high-risk women with high mammographic density, especially those with low circulating OPG levels.

Density Functional Methods for Shock Physics and High Energy Density Science

Science.gov (United States)

Desjarlais, Michael

2017-06-01

Molecular dynamics with density functional theory has emerged over the last two decades as a powerful and accurate framework for calculating thermodynamic and transport properties with broad application to dynamic compression, high energy density science, and warm dense matter. These calculations have been extensively validated against shock and ramp wave experiments, are a principal component of high-fidelity equation of state generation, and are having wide-ranging impacts on inertial confinement fusion, planetary science, and shock physics research. In addition to thermodynamic properties, phase boundaries, and the equation of state, one also has access to electrical conductivity, thermal conductivity, and lower energy optical properties. Importantly, all these properties are obtained within the same theoretical framework and are manifestly consistent. In this talk I will give a brief history and overview of molecular dynamics with density functional theory and its use in calculating a wide variety of thermodynamic and transport properties for materials ranging from ambient to extreme conditions and with comparisons to experimental data. I will also discuss some of the limitations and difficulties, as well as active research areas. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Parasitism and the biodiversity-functioning relationship

Science.gov (United States)

Frainer, André; McKie, Brendan G.; Amundsen, Per-Arne; Knudsen, Rune; Lafferty, Kevin D.

2018-01-01

Biodiversity affects ecosystem functioning.Biodiversity may decrease or increase parasitism.Parasites impair individual hosts and affect their role in the ecosystem.Parasitism, in common with competition, facilitation, and predation, could regulate BD-EF relationships.Parasitism affects host phenotypes, including changes to host morphology, behavior, and physiology, which might increase intra- and interspecific functional diversity.The effects of parasitism on host abundance and phenotypes, and on interactions between hosts and the remaining community, all have potential to alter community structure and BD-EF relationships.Global change could facilitate the spread of invasive parasites, and alter the existing dynamics between parasites, communities, and ecosystems.Species interactions can influence ecosystem functioning by enhancing or suppressing the activities of species that drive ecosystem processes, or by causing changes in biodiversity. However, one important class of species interactions – parasitism – has been little considered in biodiversity and ecosystem functioning (BD-EF) research. Parasites might increase or decrease ecosystem processes by reducing host abundance. Parasites could also increase trait diversity by suppressing dominant species or by increasing within-host trait diversity. These different mechanisms by which parasites might affect ecosystem function pose challenges in predicting their net effects. Nonetheless, given the ubiquity of parasites, we propose that parasite–host interactions should be incorporated into the BD-EF framework.

How Many Parasites Species a Frog Might Have? Determinants of Parasite Diversity in South American Anurans.

Directory of Open Access Journals (Sweden)

Karla Magalhães Campião

Full Text Available There is an increasing interest in unveiling the dynamics of parasite infection. Understanding the interaction patterns, and determinants of host-parasite association contributes to filling knowledge gaps in both community and disease ecology. Despite being targeted as a relevant group for conservation efforts, determinants of the association of amphibians and their parasites in broad scales are poorly understood. Here we describe parasite biodiversity in South American amphibians, testing the influence of host body size and geographic range in helminth parasites species richness (PSR. We also test whether parasite diversity is related to hosts' phylogenetic diversity. Results showed that nematodes are the most common anuran parasites. Host-parasite network has a nested pattern, with specialist helminth taxa generally associated with hosts that harbour the richest parasite faunas. Host size is positively correlated with helminth fauna richness, but we found no support for the association of host geographic range and PSR. These results remained consistent after correcting for uneven study effort and hosts' phylogenic correlation. However, we found no association between host and parasite diversity, indicating that more diversified anuran clades not necessarily support higher parasite diversity. Overall, considering both the structure and the determinants of PRS in anurans, we conclude that specialist parasites are more likely to be associated with large anurans, which are the ones harbouring higher PSR, and that the lack of association of PSR with hosts' clade diversification suggests it is strongly influenced by ecological and contemporary constrains.

Cyanobacteria facilitate parasite epidemics in Daphnia.

Science.gov (United States)

Tellenbach, C; Tardent, N; Pomati, F; Keller, B; Hairston, N G; Wolinska, J; Spaak, P

2016-12-01

The seasonal dominance of cyanobacteria in the phytoplankton community of lake ecosystems can have severe implications for higher trophic levels. For herbivorous zooplankton such as Daphnia, cyanobacteria have poor nutritional value and some species can produce toxins affecting zooplankton survival and reproduction. Here we present another, hitherto largely unexplored aspect of cyanobacteria, namely that they can increase Daphnia susceptibility to parasites. In a 12-yr monthly time-series analysis of the Daphnia community in Greifensee (Switzerland), we observed that cyanobacteria density correlated significantly with the epidemics of a common gut parasite of Daphnia, Caullerya mesnili, regardless of what cyanobacteria species was present or whether it was colonial or filamentous. The temperature from the previous month also affected the occurrence of Caullerya epidemics, either directly or indirectly by the promotion of cyanobacterial growth. A laboratory experiment confirmed that cyanobacteria increase the susceptibility of Daphnia to Caullerya, and suggested a possible involvement of cyanotoxins or other chemical traits of cyanobacteria in this process. These findings expand our understanding of the consequences of toxic cyanobacterial blooms for lake ecosystems and might be relevant for epidemics experienced by other aquatic species. © 2016 by the Ecological Society of America.

Morphodynamics of supercritical high-density turbidity currents

NARCIS (Netherlands)

Cartigny, M.

2012-01-01

Seafloor and outcrop observations combined with numerical and physical experiments show that turbidity currents are likely 1) to be in a supercritical flow state and 2) to carry high sediment concentrations (being of high-density). The thesis starts with an experimental study of bedforms

Foldable, High Energy Density Lithium Ion Batteries

Science.gov (United States)

Suresh, Shravan

Lithium Ion Batteries (LIBs) have become ubiquitous owing to its low cost, high energy density and, power density. Due to these advantages, LIBs have garnered a lot of attention as the primary energy storage devices in consumer electronics and electric vehicles. Recent advances in the consumer electronics research and, the drive to reduce greenhouse gases have created a demand for a shape conformable, high energy density batteries. This thesis focuses on the aforementioned two aspects of LIBs: (a) shape conformability (b) energy density and provides potential solutions to enhance them. This thesis is divided into two parts viz. (i) achieving foldability in batteries and, (ii) improving its energy density. Conventional LIBs are not shape conformable due to two limitations viz. inelasticity of metallic foils, and delamination of the active materials while bending. In the first part of the thesis (in Chapter 3), this problem is solved by replacing metallic current collector with Carbon Nanotube Macrofilms (CNMs). CNMs are superelastic films comprising of porous interconnected nanotube network. Using Molecular Dynamics (MD) simulation, we found that in the presence of an interconnected nanotube network CNMs can be fully folded. This is because the resultant stress due to bending and, the effective bending angle at the interface is reduced due to the network of nanotubes. Hence, unlike an isolated nanotube (which ruptures beyond 120 degrees of bending), a network of nanotubes can be completely folded. Thus, by replacing metallic current collector foils with CNMs, the flexibility limitation of a conventional LIB can be transcended. The second part of this thesis focusses on enhancing the energy density of LIBs. Two strategies adopted to achieve this goal are (a) removing the dead weight of the batteries, and (b) incorporating high energy density electrode materials. By incorporating CNMs, the weight of the batteries was reduced by 5-10 times due to low mass loading of

(macro- Evolutionary ecology of parasite diversity: From determinants of parasite species richness to host diversification

Directory of Open Access Journals (Sweden)

Serge Morand

2015-04-01

Full Text Available The present review summarized the factors or determinants that may explain parasite diversity among host species and the consequences of this parasite diversity on the evolution of host-life history traits. As host–parasite interactions are asymmetrical exploited–exploiter relationships, ecological and epidemiological theories produce hypotheses to find the potential determinants of parasite species richness, while life-history theory helps for testing potential consequences on parasite diversity on the evolution of hosts. This review referred only to studies that have specifically controlled or took into account phylogenetic information illustrated with parasites of mammals. Several points needing more investigation were identified with a special emphasis to develop the metabolic theory of epidemiology.

Pets and Parasites

Science.gov (United States)

... good news is that this rarely happens. Most pet-to-people diseases can be avoided by following a few ... your doctor Can a parasite cause death in people and pets? Can human disease from a parasite be treated ...

Biopolymer-nanocarbon composite electrodes for use as high-energy high-power density electrodes

Science.gov (United States)

Karakaya, Mehmet; Roberts, Mark; Arcilla-Velez, Margarita; Zhu, Jingyi; Podila, Ramakrishna; Rao, Apparao

2014-03-01

Supercapacitors (SCs) address our current energy storage and delivery needs by combining the high power, rapid switching, and exceptional cycle life of a capacitor with the high energy density of a battery. Although activated carbon is extensively used as a supercapacitor electrode due to its inexpensive nature, its low specific capacitance (100-120 F/g) fundamentally limits the energy density of SCs. We demonstrate that a nano-carbon based mechanically robust, electrically conducting, free-standing buckypaper electrode modified with an inexpensive biorenewable polymer, viz., lignin increases the electrode's specific capacitance (~ 600-700 F/g) while maintaining rapid discharge rates. In these systems, the carbon nanomaterials provide the high surface area, electrical conductivity and porosity, while the redox polymers provide a mechanism for charge storage through Faradaic charge transfer. The design of redox polymers and their incorporation into nanomaterial electrodes will be discussed with a focus on enabling high power and high energy density electrodes. Research supported by US NSF CMMI Grant 1246800.

Breast density estimation from high spectral and spatial resolution MRI

Science.gov (United States)

Li, Hui; Weiss, William A.; Medved, Milica; Abe, Hiroyuki; Newstead, Gillian M.; Karczmar, Gregory S.; Giger, Maryellen L.

2016-01-01

Abstract. A three-dimensional breast density estimation method is presented for high spectral and spatial resolution (HiSS) MR imaging. Twenty-two patients were recruited (under an Institutional Review Board--approved Health Insurance Portability and Accountability Act-compliant protocol) for high-risk breast cancer screening. Each patient received standard-of-care clinical digital x-ray mammograms and MR scans, as well as HiSS scans. The algorithm for breast density estimation includes breast mask generating, breast skin removal, and breast percentage density calculation. The inter- and intra-user variabilities of the HiSS-based density estimation were determined using correlation analysis and limits of agreement. Correlation analysis was also performed between the HiSS-based density estimation and radiologists’ breast imaging-reporting and data system (BI-RADS) density ratings. A correlation coefficient of 0.91 (pdensity estimations. An interclass correlation coefficient of 0.99 (pdensity estimations. A moderate correlation coefficient of 0.55 (p=0.0076) was observed between HiSS-based breast density estimations and radiologists’ BI-RADS. In summary, an objective density estimation method using HiSS spectral data from breast MRI was developed. The high reproducibility with low inter- and low intra-user variabilities shown in this preliminary study suggest that such a HiSS-based density metric may be potentially beneficial in programs requiring breast density such as in breast cancer risk assessment and monitoring effects of therapy. PMID:28042590

Host-parasite interactions in sympatric and allopatric populations of European bitterling.

Science.gov (United States)

Francová, Kateřina; Ondračková, Markéta

2011-09-01

Susceptibility to parasite infection was examined in a field experiment for four populations of 0+ juvenile European bitterling (Rhodeus amarus): one sympatric to local parasite fauna, one allopatric, and two hybrid populations. Significantly higher parasite abundance was recorded in the allopatric bitterling population, suggesting a maladaptation of parasites to their sympatric host. Type of parasite life cycle played an important role in host-parasite interactions. While the abundance of allogenic species between populations was comparable, a significant difference was found in abundance of autogenic parasite species between fish populations, with the allopatric population more infected. These results correspond with a prediction of higher dispersion probability and higher gene flow among geographically distant populations of allogenic species as compared to autogenic species. Increased susceptibility to parasites that do not occur within the natural host's geographical distribution was found in the allopatric host, but only for autogenic species. A difference in infection susceptibility was detected among populations of early-hatched bitterling exposed to infection during a period of high parasite abundance and richness in the environment. Differences in parasite abundance and species diversity among populations diminished, however, with increasing time of exposure. No difference was found within late-hatched populations, probably due to a lower probability of infection in late-hatched cohorts.

High dislocation density of tin induced by electric current

International Nuclear Information System (INIS)

Liao, Yi-Han; Liang, Chien-Lung; Lin, Kwang-Lung; Wu, Albert T.

2015-01-01

A dislocation density of as high as 10 17 /m 2 in a tin strip, as revealed by high resolution transmission electron microscope, was induced by current stressing at 6.5 x 10 3 A/ cm 2 . The dislocations exist in terms of dislocation line, dislocation loop, and dislocation aggregates. Electron Backscattered Diffraction images reflect that the high dislocation density induced the formation of low deflection angle subgrains, high deflection angle Widmanstätten grains, and recrystallization. The recrystallization gave rise to grain refining

Neglected Parasitic Infections: Toxocariasis

Centers for Disease Control (CDC) Podcasts

2012-01-05

This podcast is an overview of the Clinician Outreach and Communication Activity (COCA) Call: Neglected Parasitic Infections in the United States. Neglected Parasitic Infections are a group of diseases that afflict vulnerable populations and are often not well studied or diagnosed. A subject matter expert from CDC's Division of Parasitic Diseases and Malaria describes the epidemiology, diagnosis, and treatment of toxocariasis.  Created: 1/5/2012 by Center for Global Health, Division of Parasitic Diseases and Malaria (DPDM); Emergency Risk Communication Branch (ERCB)/Joint Information Center (JIC), Office of Public Health Preparedness and Response (OPHPR).   Date Released: 1/9/2012.

Preparation and characterization of high-Tc superconducting thin films with high critical current densities

International Nuclear Information System (INIS)

Vase, P.

1991-08-01

The project was carried out in relation to possible cable and electronics applications of high-T c materials. Laser ablation was used as the deposition technique because of its stoichiometry conservation. Films were made in the YBa 2 Cu 3 O 7 compound due to its relatively simple stoichiometry compared to other High-T c compounds. Much attention was paid to the critical current density. A very high critical current density was reached. By using texture analysis by X-ray diffraction, it was found that films with high critical current densities were epitaxial, while films with low critical current densities contained several crystalline orientations. Four techniques for patterning the films were used - photo lithography and wet etch, laser ablation lithography, laser writing and electron beam lithography and ion milling. Sub-micron patterning has been demonstrated without degradation of the superconducting properties. The achieved patterning resolution is sufficient for preparation of many superconducting components. (AB)

Host nutrition alters the variance in parasite transmission potential.

Science.gov (United States)

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.

Changing perceptions of hunger on a high nutrient density diet

Directory of Open Access Journals (Sweden)

Glaser Dale

2010-11-01

Full Text Available Abstract Background People overeat because their hunger directs them to consume more calories than they require. The purpose of this study was to analyze the changes in experience and perception of hunger before and after participants shifted from their previous usual diet to a high nutrient density diet. Methods This was a descriptive study conducted with 768 participants primarily living in the United States who had changed their dietary habits from a low micronutrient to a high micronutrient diet. Participants completed a survey rating various dimensions of hunger (physical symptoms, emotional symptoms, and location when on their previous usual diet versus the high micronutrient density diet. Statistical analysis was conducted using non-parametric tests. Results Highly significant differences were found between the two diets in relation to all physical and emotional symptoms as well as the location of hunger. Hunger was not an unpleasant experience while on the high nutrient density diet, was well tolerated and occurred with less frequency even when meals were skipped. Nearly 80% of respondents reported that their experience of hunger had changed since starting the high nutrient density diet, with 51% reporting a dramatic or complete change in their experience of hunger. Conclusions A high micronutrient density diet mitigates the unpleasant aspects of the experience of hunger even though it is lower in calories. Hunger is one of the major impediments to successful weight loss. Our findings suggest that it is not simply the caloric content, but more importantly, the micronutrient density of a diet that influences the experience of hunger. It appears that a high nutrient density diet, after an initial phase of adjustment during which a person experiences "toxic hunger" due to withdrawal from pro-inflammatory foods, can result in a sustainable eating pattern that leads to weight loss and improved health. A high nutrient density diet provides

High power density yeast catalyzed microbial fuel cells

Science.gov (United States)

Ganguli, Rahul

Microbial fuel cells leverage whole cell biocatalysis to convert the energy stored in energy-rich renewable biomolecules such as sugar, directly to electrical energy at high efficiencies. Advantages of the process include ambient temperature operation, operation in natural streams such as wastewater without the need to clean electrodes, minimal balance-of-plant requirements compared to conventional fuel cells, and environmentally friendly operation. These make the technology very attractive as portable power sources and waste-to-energy converters. The principal problem facing the technology is the low power densities compared to other conventional portable power sources such as batteries and traditional fuel cells. In this work we examined the yeast catalyzed microbial fuel cell and developed methods to increase the power density from such fuel cells. A combination of cyclic voltammetry and optical absorption measurements were used to establish significant adsorption of electron mediators by the microbes. Mediator adsorption was demonstrated to be an important limitation in achieving high power densities in yeast-catalyzed microbial fuel cells. Specifically, the power densities are low for the length of time mediator adsorption continues to occur. Once the mediator adsorption stops, the power densities increase. Rotating disk chronoamperometry was used to extract reaction rate information, and a simple kinetic expression was developed for the current observed in the anodic half-cell. Since the rate expression showed that the current was directly related to microbe concentration close to the electrode, methods to increase cell mass attached to the anode was investigated. Electrically biased electrodes were demonstrated to develop biofilm-like layers of the Baker's yeast with a high concentration of cells directly connected to the electrode. The increased cell mass did increase the power density 2 times compared to a non biofilm fuel cell, but the power density

The Influence of Decreased Levels of High Density Lipoprotein ...

African Journals Online (AJOL)

very low density lipoprotein cholesterol, and triglyceride were assayed. ... Abiodun and Gwarzo: Association of high density lipoprotein cholesterol with haemolysis in sickle cell disease ... analyses were carried out to determine the correlation.

High Power Density Power Electronic Converters for Large Wind Turbines

DEFF Research Database (Denmark)

Senturk, Osman Selcuk

. For these VSCs, high power density is required due to limited turbine nacelle space. Also, high reliability is required since maintenance cost of these remotely located wind turbines is quite high and these turbines operate under harsh operating conditions. In order to select a high power density and reliability......In large wind turbines (in MW and multi-MW ranges), which are extensively utilized in wind power plants, full-scale medium voltage (MV) multi-level (ML) voltage source converters (VSCs) are being more preferably employed nowadays for interfacing these wind turbines with electricity grids...... VSC solution for wind turbines, first, the VSC topology and the switch technology to be employed should be specified such that the highest possible power density and reliability are to be attained. Then, this qualitative approach should be complemented with the power density and reliability...

High density implosion experiments at Nova

International Nuclear Information System (INIS)

Cable, M.D.; Hatchett, S.P.; Nelson, M.B.; Lerche, R.A.; Murphy, T.J.; Ress, D.B.

1994-01-01

Deuterium filled glass microballoons are used as indirectly driven targets for implosion experiments at the Nova Laser Fusion Facility. High levels of laser precision were required to achieve fuel densities and convergences to an ignition scale hot spot. (AIP) copyright 1994 American Institute of Physics

Neglected Parasitic Infections: Toxocariasis

Centers for Disease Control (CDC) Podcasts

This podcast is an overview of the Clinician Outreach and Communication Activity (COCA) Call: Neglected Parasitic Infections in the United States. Neglected Parasitic Infections are a group of diseases that afflict vulnerable populations and are often not well studied or diagnosed. A subject matter expert from CDC's Division of Parasitic Diseases and Malaria describes the epidemiology, diagnosis, and treatment of toxocariasis.

Gastrointestinal parasites and Trypanosoma evansi in buffaloes

International Nuclear Information System (INIS)

Sani, R.A.; Chandrawathani, P.; Rosli, M.

1990-01-01

Gastrointestinal parasitism is common in buffalo calves. The effect of helminths on growth was studied by administration of an anthelmintic to buffalo calves following natural infections with gastrointestinal parasites. In studies conducted on calves belonging to an institute and a smallholder farmer, the treated calves showed improved weight gains. Serial parasitic examinations showed these animals had moderate to high faecal counts with Strongyloides, Toxocara vitulorum and Haemonchus eggs and Eimeria oocytes. In another study, there was no live weight advantage in treated over untreated calves. Few animals in this study had evidence of parasites and even those which were infested had low faecal egg counts. Hence, in general, helminths at certain levels of infection do affect the live weight gains of young buffalo calves. The prevalence of Trypanosoma evansi, as assessed parasitologically using the haematocrit centrifugation technique and mice inoculation, was 2.7 and 1%, respectively, in cattle and buffaloes. The serological prevalence using the enzyme linked immunosorbent assay was 35 and 2% for cattle and buffaloes, respectively. (author). 6 refs, 5 figs, 2 tabs

Genome Evolution of Plant-Parasitic Nematodes.

Science.gov (United States)

Kikuchi, Taisei; Eves-van den Akker, Sebastian; Jones, John T

2017-08-04

Plant parasitism has evolved independently on at least four separate occasions in the phylum Nematoda. The application of next-generation sequencing (NGS) to plant-parasitic nematodes has allowed a wide range of genome- or transcriptome-level comparisons, and these have identified genome adaptations that enable parasitism of plants. Current genome data suggest that horizontal gene transfer, gene family expansions, evolution of new genes that mediate interactions with the host, and parasitism-specific gene regulation are important adaptations that allow nematodes to parasitize plants. Sequencing of a larger number of nematode genomes, including plant parasites that show different modes of parasitism or that have evolved in currently unsampled clades, and using free-living taxa as comparators would allow more detailed analysis and a better understanding of the organization of key genes within the genomes. This would facilitate a more complete understanding of the way in which parasitism has shaped the genomes of plant-parasitic nematodes.

Ornamental fish goldfish,Carassius auratusand related parasites in three districts of West Bengal, India

Directory of Open Access Journals (Sweden)

Mukti Chanda

2011-01-01

Full Text Available The lucrative business of ornamental fish culture in West Bengal (Mainly in three districts-Howrah, North and South 24 Parganas are facing loses due to the invasion of different ecto- and endo-parasites. The present study shows that the ornamental fish (Goldfish - Carassius auratus are mainly affected with ecto-parasites like Ichthyophthirius sp., Dactylogyrus sp., Gyrodactylus sp., Argulus sp. and endo-parasites like Procamallanus sp. and Cucullanus sp. The intensity of infection is high in case of Ichthyophthirius sp. and the intensity of the infection is high in summer months when the temperature is high or moderately high. In cooler months the intensity of the infection is lower as because the parasites are unable to breed or scarcity of food particles.

Study of the parasitic oscillations in a gyrotron; Etudes des oscillations parasites dans un gyrotron

Energy Technology Data Exchange (ETDEWEB)

Pedrozzi, M. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

1997-01-01

This work is dedicated to the study of parasitic instabilities in a gyrotron, and to the influence of such instabilities on the interaction efficiency. The gyrotron is a high-power millimeter wave radiation source, based on the resonant interaction between a weakly relativistic electron beam immersed in a guiding magnetic field, and an electromagnetic wave. The gyrotron investigated here operates at a frequency close to 100 GHz: its main feature is that it is quasi optical. In this configuration, the electron beam interacts with a high order TEM eigenmode of a Fabry-Perot resonator, the axis of which is perpendicular to the electron beam path. During the development of this source, the highest efficiency that was achieved is approximately 30% lower than the theoretical predictions. At the same time, parasitic oscillations at frequencies close to the maximum relativistic cyclotronic frequency are detected. The power associated with these oscillations ranges from a few watts to a few kilowatts, with threshold currents of the order of 100 mA. It is suspected that the excitation of parasitic oscillations in the beam duct section before the interaction region might have a dramatic effect on the electron beam distribution function inducing, in particular, an energy spread. The cyclotron maser instability responsible for the energy exchange between particles and fields in a gyrotron, is very sensitive to energy spreads. It is thus necessary to identify the origin of the parasitic radiation. A few physical mechanisms suspected to lead to a degradation of the electron beam properties were investigated: the cyclotron maser process itself, the Bernstein electrostatic instability and the Langmuir instability. The experimental work concentrated on the study of the beam ducts between the electron gun and the resonant cavity. (author) figs., tabs., 90 refs.

Status of intestinal parasitic infections among residents of Jimma Town, Ethiopia

OpenAIRE

Jejaw, Ayalew; Zeynudin, Ahmed; Zemene, Endalew; Belay, Tariku

2014-01-01

Background Intestinal parasites cause considerable morbidity and mortality in the world, especially in developing countries like Ethiopia. Both urban and rural inhabitants are vulnerable to infection with intestinal parasites in developing countries. The aim of this study was to determine the status of intestinal parasitic infections (IPIs) among residents of Jimma Town, seven years after high prevalence was reported. Results Four hundred and thirty four residents of Jimma Town were included ...

High-energy density physics at Los Alamos

International Nuclear Information System (INIS)

Byrnes, P.; Younger, S.M.

1993-03-01

This brochure describes the facilities of the Above Ground Experiments II (AGEX II) and the Inertial Confinement Fusion (ICF) programs at Los Alamo. Combined, these programs represent, an unparalleled capability to address important issues in high-energy density physics that are critical to the future defense, energy, and research needs of th e United States. The mission of the AGEX II program at Los Alamos is to provide additional experimental opportunities for the nuclear weapons program. For this purpose we have assembled at Los Alamos the broadest array of high-energy density physics facilities of any laboratory in the world. Inertial confinement fusion seeks to achieve thermonuclear burn on a laboratory scale through the implosion of a small quantity of deuterium and tritium fuel to very high Pressure and temperature.The Los Alamos ICF program is focused on target physics. With the largest scientific computing center in the world, We can perform calculations of unprecedented sophistication and precision. We field experiments at facilities worldwide-including our own Trident and Mercury lasers-to confirm our understanding and to provide the necessary data base to proceed toward the historic goal of controlled fusion in the laboratory. In addition to direct programmatic high-energy density physics is a nc scientific endeavor in itself. The ultrahigh magnetic fields produced in our high explosive pulsed-power generators can be used in awide variety of solid state physics and temperature superconductor studies. The structure and dynamics of planetary atmospheres can be simulated through the compression of gas mixtures

Workshop on High Power ICH Antenna Designs for High Density Tokamaks

Science.gov (United States)

Aamodt, R. E.

1990-02-01

A workshop in high power ICH antenna designs for high density tokamaks was held to: (1) review the data base relevant to the high power heating of high density tokamaks; (2) identify the important issues which need to be addressed in order to ensure the success of the ICRF programs on CIT and Alcator C-MOD; and (3) recommend approaches for resolving the issues in a timely realistic manner. Some specific performance goals for the antenna system define a successful design effort. Simply stated these goals are: couple the specified power per antenna into the desired ion species; produce no more than an acceptable level of RF auxiliary power induced impurities; and have a mechanical structure which safely survives the thermal, mechanical and radiation stresses in the relevant environment. These goals are intimately coupled and difficult tradeoffs between scientific and engineering constraints have to be made.

Does habitat disturbance affect stress, body condition and parasitism in two sympatric lemurs?

Science.gov (United States)

Rakotoniaina, Josué H; Kappeler, Peter M; Ravoniarimbinina, Pascaline; Pechouskova, Eva; Hämäläinen, Anni M; Grass, Juliane; Kirschbaum, Clemens; Kraus, Cornelia

2016-01-01

Understanding how animals react to human-induced changes in their environment is a key question in conservation biology. Owing to their potential correlation with fitness, several physiological parameters are commonly used to assess the effect of habitat disturbance on animals' general health status. Here, we studied how two lemur species, the fat-tailed dwarf lemur (Cheirogaleus medius) and the grey mouse lemur (Microcebus murinus), respond to changing environmental conditions by comparing their stress levels (measured as hair cortisol concentration), parasitism and general body condition across four habitats ordered along a gradient of human disturbance at Kirindy Forest, Western Madagascar. These two species previously revealed contrasting responses to human disturbance; whereas M. murinus is known as a resilient species, C. medius is rarely encountered in highly disturbed habitats. However, neither hair cortisol concentrations nor parasitism patterns (prevalence, parasite species richness and rate of multiple infections) and body condition varied across the gradient of anthropogenic disturbance. Our results indicate that the effect of anthropogenic activities at Kirindy Forest is not reflected in the general health status of both species, which may have developed a range of behavioural adaptations to deal with suboptimal conditions. Nonetheless, a difference in relative density among sites suggests that the carrying capacity of disturbed habitat is lower, and both species respond differently to environmental changes, with C. medius being more negatively affected. Thus, even for behaviourally flexible species, extended habitat deterioration could hamper long-term viability of populations.

Plasma Diagnostics in High Density Reactors

International Nuclear Information System (INIS)

Daltrini, A. M.; Moshkalyov, S.; Monteiro, M. J. R.; Machida, M.; Kostryukov, A.; Besseler, E.; Biasotto, C.; Diniz, J. A.

2006-01-01

Langmuir electric probes and optical emission spectroscopy diagnostics were developed for applications in high density plasmas. These diagnostics were employed in two plasma sources: an electron cyclotron resonance (ECR) plasma and an RF driven inductively coupled plasma (ICP) plasma. Langmuir probes were tested using a number of probing dimensions, probe tip materials, circuits for probe bias and filters. Then, the results were compared with the optical spectroscopy measurements. With these diagnostics, analyses of various plasma processes were performed in both reactors. For example, it has been shown that species like NH radicals generated in gas phase can have critical impact on films deposited by ECR plasmas. In the ICP source, plasmas in atomic and molecular gases were shown to have different spatial distributions, likely due to nonlocal electron heating. The low-to-high density transitions in the ICP plasma were also studied. The role of metastables is shown to be significant in Ar plasmas, in contrast to plasmas with additions of molecular gases

Possible new form of matter at high density

International Nuclear Information System (INIS)

Lee, T.D.

1974-01-01

As a preliminary to discussion of the possibility of new forms of matter at high density, questions relating to the vacuum and vacuum excitation are considered. A quasi-classical approach to the development of abnormal nuclear states is undertaken using a Fermi gas of nucleons of uniform density. Discontinuous transitions are considered in the sigma model (tree approximation) followed by brief consideration of higher order loop diagrams. Production and detection of abnormal nuclear states are discussed in the context of high energy heavy ion collisions. Remarks are made on motivation for such research. 8 figures

Parasitic diseases of lungs

International Nuclear Information System (INIS)

Rozenshtraukh, L.C.; Rybakova, N.I.; Vinner, M.G.

1987-01-01

Roentgenologic semiotics of the main parasitic diseases of lungs is described: echinococcosis, paragonimiasis, cysticercosis, toxoplasmosis, ascariasis, amebiosis and some rarely met parasitic diseases

The high density effects in the Drell-Yan process

International Nuclear Information System (INIS)

Betemps, M.A.; Gay Ducati, M.B.; Ayala Filho, A.L.

2003-01-01

The high density effects in the Drell-Yan process (q q-bar → γ * →l + l - ) are investigated for pA collisions at RHIC and LHC energies. In particular, we use a set of nuclear parton distributions that describes the present nuclear eA and pA data in the DGLAP approach including the high density effects introduced in the perturbative Glauber-Mueller approach. (author)

BCS Theory of Hadronic Matter at High Densities

DEFF Research Database (Denmark)

Bohr, Henrik; Panda, Prafulla K.; Providencia, Constanca

2012-01-01

The equilibrium between the so-called 2SC and CFL phases of strange quark matter at high densities is investigated in the framework of a simple schematic model of the NJL type. Equal densities are assumed for quarks u, d and s. The 2SC phase is here described by a color-flavor symmetric state, in...

[Screening of parasitic diseases in the asymptomatic immigrant population].

Science.gov (United States)

Goterris, Lidia; Bocanegra, Cristina; Serre-Delcor, Núria; Moure, Zaira; Treviño, Begoña; Zarzuela, Francesc; Espasa, Mateu; Sulleiro, Elena

2016-07-01

Parasitic diseases suppose an important health problem in people from high endemic areas, so these must be discarded properly. Usually, these infections develop asymptomatically but, in propitious situations, are likely to reactivate themselves and can cause clinical symptoms and/or complications in the receiving country. Moreover, in some cases it is possible local transmission. Early diagnosis of these parasitic diseases made by appropriate parasitological techniques and its specific treatment will benefit both, the individual and the community. These techniques must be selected according to geoepidemiological criteria, patient's origin, migration route or time spent outside the endemic area; but other factors must also be considered as its sensitivity and specificity, implementation experience and availability. Given the high prevalence of intestinal parasites on asymptomatic immigrants, it is recommended to conduct a study by coproparasitological techniques. Because of its potential severity, the screening of asymptomatic malaria with sensitive techniques such as PCR (polymerase chain reaction) is also advisable. Serological screening for Chagas disease should be performed on all Latin American immigrants, except for people from the Caribbean islands. Other important parasites, which should be excluded, are filariasis and urinary schistosomiasis, by using microscopic examination. The aim of this paper is to review the different techniques for the screening of parasitic diseases and its advices within the care protocols for asymptomatic immigrants. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Parasitic helminths: a pharmacopeia of anti-inflammatory molecules.

Science.gov (United States)

Johnston, M J G; MacDonald, J A; McKay, D M

2009-02-01

Infection with parasitic helminths takes a heavy toll on the health and well-being of humans and their domestic livestock, concomitantly resulting in major economic losses. Analyses have consistently revealed bioactive molecules in extracts of helminths or in their excretory/secretory products that modulate the immune response of the host. It is our view that parasitic helminths are an untapped source of immunomodulatory substances that, in pure form, could become new drugs (or models for drug design) to treat disease. Here, we illustrate the range of immunomodulatory molecules in selected parasitic trematodes, cestodes and nematodes, their impact on the immune cells in the host and how the host may recognize these molecules. There are many examples of the partial characterization of helminth-derived immunomodulatory molecules, but these have not yet translated into new drugs, reflecting the difficulty of isolating and fully characterizing proteins, glycoproteins and lipid-based molecules from small amounts of parasite material. However, this should not deter the investigator, since analytical techniques are now being used to accrue considerable structural information on parasite-derived molecules, even when only minute quantities of tissue are available. With the introduction of methodologies to purify and structurally-characterize molecules from small amounts of tissue and the application of high throughput immunological assays, one would predict that an assessment of parasitic helminths will yield a variety of novel drug candidates in the coming years.

Genetic variation for maternal effects on parasite susceptibility.

Science.gov (United States)

Stjernman, M; Little, T J

2011-11-01

The expression of infectious disease is increasingly recognized to be impacted by maternal effects, where the environmental conditions experienced by mothers alter resistance to infection in offspring, independent of heritability. Here, we studied how maternal effects (high or low food availability to mothers) mediated the resistance of the crustacean Daphnia magna to its bacterial parasite Pasteuria ramosa. We sought to disentangle maternal effects from the effects of host genetic background by studying how maternal effects varied across 24 host genotypes sampled from a natural population. Under low-food conditions, females produced offspring that were relatively resistant, but this maternal effect varied strikingly between host genotypes, i.e. there were genotype by maternal environment interactions. As infection with P. ramosa causes a substantial reduction in host fecundity, this maternal effect had a large effect on host fitness. Maternal effects were also shown to impact parasite fitness, both because they prevented the establishment of the parasites and because even when parasites did establish in the offspring of poorly fed mothers, and they tended to grow more slowly. These effects indicate that food stress in the maternal generation can greatly influence parasite susceptibility and thus perhaps the evolution and coevolution of host-parasite interactions. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

Sr-doped Lanthanum Nickelate Nanofibers for High Energy Density Supercapacitors

International Nuclear Information System (INIS)

Cao, Yi; Lin, Baoping; Sun, Ying; Yang, Hong; Zhang, Xueqin

2015-01-01

Highlights: • The electrode made by LNF-0.7 possessed excellent performance (719 F g −1 ) at Na 2 SO 4 electrolyte • LNF-0.7//LNF-0.7 symmetric supercapacitor device were firstly prepared • The maximum energy density of 81.4 Wh·kg −1 are achieved at a power density of 500W·kg −1 • This symmetric supercapacitor also shows an excellent cycling life - Abstract: The series La x Sr 1−x NiO 3−δ (0.3≤x≤1) nanofibers (LNF-x) samples are prepared by using electrospun method. We investigate the structure and the electrochemical properties of LNF-x in detail. As a result, LNF-x nanofibers present a perovskite structure, and the LNF-0.7 sample with high specific surface area display remarkable performance as an electrode material for supercapacitors. The maximum specific capacitance value of 719 F·g −1 at a current density of 2 A·g −1 , which retains 505 F·g −1 at a high current density of 20 A·g −1 , is obtained for LNF-0.7 electrode in 1 M Na 2 SO 4 aqueous electrolyte. Moreover, the LNF-0.7//LNF-0.7 symmetric supercapacitor device using 1 M Na 2 SO 4 aqueous solution is successfully demonstrated. The capacitor device can operate at a cell voltage as high as 2 V, and it exhibits an energy density of 30.5 Wh·kg −1 at a high power density of 10 kW·kg −1 and a high energy density of 81.4 Wh·kg −1 at a low power density of 500 W·kg −1 . More importantly, this symmetric supercapacitor also shows an excellent cycling performance with 90% specific capacitance retention after 2000 charging and discharging cycles. Those results offer a suitable design of electrode materials for high-performance supercapacitors

High-Stacking-Density, Superior-Roughness LDH Bridged with Vertically Aligned Graphene for High-Performance Asymmetric Supercapacitors.

Science.gov (United States)

Guo, Wei; Yu, Chang; Li, Shaofeng; Yang, Juan; Liu, Zhibin; Zhao, Changtai; Huang, Huawei; Zhang, Mengdi; Han, Xiaotong; Niu, Yingying; Qiu, Jieshan

2017-10-01

The high-performance electrode materials with tuned surface and interface structure and functionalities are highly demanded for advanced supercapacitors. A novel strategy is presented to conFigure high-stacking-density, superior-roughness nickel manganese layered double hydroxide (LDH) bridged by vertically aligned graphene (VG) with nickel foam (NF) as the conductive collector, yielding the LDH-NF@VG hybrids for asymmetric supercapacitors. The VG nanosheets provide numerous electron transfer channels for quick redox reactions, and well-developed open structure for fast mass transport. Moreover, the high-stacking-density LDH grown and assembled on VG nanosheets result in a superior hydrophilicity derived from the tuned nano/microstructures, especially microroughness. Such a high stacking density with abundant active sites and superior wettability can be easily accessed by aqueous electrolytes. Benefitting from the above features, the LDH-NF@VG can deliver a high capacitance of 2920 F g -1 at a current density of 2 A g -1 , and the asymmetric supercapacitor with the LDH-NF@VG as positive electrode and activated carbon as negative electrode can deliver a high energy density of 56.8 Wh kg -1 at a power density of 260 W kg -1 , with a high specific capacitance retention rate of 87% even after 10 000 cycles. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Parasite Infection, Carcinogenesis and Human Malignancy

Directory of Open Access Journals (Sweden)

Hoang van Tong

2017-02-01

Full Text Available Cancer may be induced by many environmental and physiological conditions. Infections with viruses, bacteria and parasites have been recognized for years to be associated with human carcinogenicity. Here we review current concepts of carcinogenicity and its associations with parasitic infections. The helminth diseases schistosomiasis, opisthorchiasis, and clonorchiasis are highly carcinogenic while the protozoan Trypanosoma cruzi, the causing agent of Chagas disease, has a dual role in the development of cancer, including both carcinogenic and anticancer properties. Although malaria per se does not appear to be causative in carcinogenesis, it is strongly associated with the occurrence of endemic Burkitt lymphoma in areas holoendemic for malaria. The initiation of Plasmodium falciparum related endemic Burkitt lymphoma requires additional transforming events induced by the Epstein-Barr virus. Observations suggest that Strongyloides stercoralis may be a relevant co-factor in HTLV-1-related T cell lymphomas. This review provides an overview of the mechanisms of parasitic infection-induced carcinogenicity.

Parasite Infection, Carcinogenesis and Human Malignancy.

Science.gov (United States)

van Tong, Hoang; Brindley, Paul J; Meyer, Christian G; Velavan, Thirumalaisamy P

2017-02-01

Cancer may be induced by many environmental and physiological conditions. Infections with viruses, bacteria and parasites have been recognized for years to be associated with human carcinogenicity. Here we review current concepts of carcinogenicity and its associations with parasitic infections. The helminth diseases schistosomiasis, opisthorchiasis, and clonorchiasis are highly carcinogenic while the protozoan Trypanosoma cruzi, the causing agent of Chagas disease, has a dual role in the development of cancer, including both carcinogenic and anticancer properties. Although malaria per se does not appear to be causative in carcinogenesis, it is strongly associated with the occurrence of endemic Burkitt lymphoma in areas holoendemic for malaria. The initiation of Plasmodium falciparum related endemic Burkitt lymphoma requires additional transforming events induced by the Epstein-Barr virus. Observations suggest that Strongyloides stercoralis may be a relevant co-factor in HTLV-1-related T cell lymphomas. This review provides an overview of the mechanisms of parasitic infection-induced carcinogenicity. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

One Health: parasites and beyond.

Science.gov (United States)

Blake, Damer P; Betson, Martha

2017-01-01

The field of parasitism is broad, encompassing relationships between organisms where one benefits at the expense of another. Traditionally the discipline focuses on eukaryotes, with the study of bacteria and viruses complementary but distinct. Nonetheless, parasites vary in size and complexity from single celled protozoa, to enormous plants like those in the genus Rafflesia. Lifecycles range from obligate intracellular to extensive exoparasitism. Examples of parasites include high-profile medical and zoonotic pathogens such as Plasmodium, veterinary pathogens of wild and captive animals and many of the agents which cause neglected tropical diseases, stretching to parasites which infect plants and other parasites (e.g. Kikuchi et al. 2011; Hotez et al. 2014; Blake et al. 2015; Hemingway, 2015; Meekums et al. 2015; Sandlund et al. 2015). The breadth of parasitology has been matched by the variety of ways in which parasites are studied, drawing upon biological, chemical, molecular, epidemiological and other expertise. Despite such breadth bridging between disciplines has commonly been problematic, regardless of extensive encouragement from government agencies, peer audiences and funding bodies promoting multidisciplinary research. Now, progress in understanding and collaboration can benefit from establishment of the One Health concept (Zinsstag et al. 2012; Stark et al. 2015). One Health draws upon biological, environmental, medical, veterinary and social science disciplines in order to improve human, animal and environmental health, although it remains tantalizingly difficult to engage many relevant parties. For infectious diseases traditional divides have been exacerbated as the importance of wildlife reservoirs, climate change, food production systems and socio-economic diversity have been recognized but often not addressed in a multidisciplinary manner. In response the 2015 Autumn Symposium organized by the British Society for Parasitology (BSP; https

Host-Parasite Interactions and Purifying Selection in a Microsporidian Parasite of Honey Bees.

Science.gov (United States)

Huang, Qiang; Chen, Yan Ping; Wang, Rui Wu; Cheng, Shang; Evans, Jay D

2016-01-01

To clarify the mechanisms of Nosema ceranae parasitism, we deep-sequenced both honey bee host and parasite mRNAs throughout a complete 6-day infection cycle. By time-series analysis, 1122 parasite genes were significantly differently expressed during the reproduction cycle, clustering into 4 expression patterns. We found reactive mitochondrial oxygen species modulator 1 of the host to be significantly down regulated during the entire infection period. Our data support the hypothesis that apoptosis of honey bee cells was suppressed during infection. We further analyzed genome-wide genetic diversity of this parasite by comparing samples collected from the same site in 2007 and 2013. The number of SNP positions per gene and the proportion of non-synonymous substitutions per gene were significantly reduced over this time period, suggesting purifying selection on the parasite genome and supporting the hypothesis that a subset of N. ceranae strains might be dominating infection.

Edge density profiles in high-performance JET plasmas

International Nuclear Information System (INIS)

Summers, D.D.R.; Viaccoz, B.; Vince, J.

1997-01-01

Detailed electron density profiles of the scrape-off layer in high-performance JET plasmas (plasma current, I p nbi ∝17 MW) have been measured by means of a lithium beam diagnostic system featuring high spatial resolution [Kadota (1978)[. Measurements were taken over a period of several seconds, allowing examination of the evolution of the edge profile at a location upstream from the divertor target. The data clearly show the effects of the H-mode transition - an increase in density near the plasma separatrix and a reduction in density scrape-off length. The profiles obtained under various plasma conditions are compared firstly with data from other diagnostics, located elsewhere in the vessel, and also with the predictions of an 'onion-skin' model (DIVIMP), which used, as initial parameters, data from an array of probes located in the divertor target. (orig.)

Everyday and Exotic Foodborne Parasites

Directory of Open Access Journals (Sweden)

Marilyn B Lee

2000-01-01

Full Text Available Everyday foodborne parasites, which are endemic in Canada, include the protozoans Entamoeba histolytica, Giardia lamblia and Cryptosporidium parvum. However, these parasites are most frequently acquired through unfiltered drinking water, homosexual activity or close personal contact such as in daycare centres and occasionally via a food vehicle. It is likely that many foodborne outbreaks from these protozoa go undetected. Transmission of helminth infections, such as tapeworms, is rare in Canada because of effective sewage treatment. However, a common foodborne parasite of significance is Toxoplasma gondii. Although infection can be acquired from accidental ingestion of oocysts from cat feces, infection can also result from consumption of tissue cysts in undercooked meat, such as pork or lamb. Congenital transmission poses an immense financial burden, costing Canada an estimated $240 million annually. Also of concern is toxoplasmosis in AIDS patients, which may lead to toxoplasmosis encephalitis, the second most common AIDS-related opportunistic infection of the central nervous system. Exotic parasites (ie, those acquired from abroad or from imported food are of growing concern because more Canadians are travelling and the number of Canada?s trading partners is increasing. Since 1996, over 3000 cases of Cyclospora infection reported in the United States and Canada were epidemiologically associated with importation of Guatemalan raspberries. Unlike toxoplasmosis, where strategies for control largely rest with individual practices, control of cyclosporiasis rests with government policy, which should prohibit the importation of foods at high risk.

Advances in the application of genetic manipulation methods to apicomplexan parasites

Science.gov (United States)

Apicomplexan parasites such as Babesia, Theileria, Cryptosporidium, and Toxoplasma have a high negative impact on animal health globally, and improved, cost-effective measures to control them are urgently required. These parasites have complex multi-stage life cycles including obligate intracellular...

High Density Lipoprotein and it's Dysfunction.

Science.gov (United States)

Eren, Esin; Yilmaz, Necat; Aydin, Ozgur

2012-01-01

Plasma high-density lipoprotein cholesterol(HDL-C) levels do not predict functionality and composition of high-density lipoprotein(HDL). Traditionally, keeping levels of low-density lipoprotein cholesterol(LDL-C) down and HDL-C up have been the goal of patients to prevent atherosclerosis that can lead to coronary vascular disease(CVD). People think about the HDL present in their cholesterol test, but not about its functional capability. Up to 65% of cardiovascular death cannot be prevented by putative LDL-C lowering agents. It well explains the strong interest in HDL increasing strategies. However, recent studies have questioned the good in using drugs to increase level of HDL. While raising HDL is a theoretically attractive target, the optimal approach remains uncertain. The attention has turned to the quality, rather than the quantity, of HDL-C. An alternative to elevations in HDL involves strategies to enhance HDL functionality. The situation poses an opportunity for clinical chemists to take the lead in the development and validation of such biomarkers. The best known function of HDL is the capacity to promote cellular cholesterol efflux from peripheral cells and deliver cholesterol to the liver for excretion, thereby playing a key role in reverse cholesterol transport (RCT). The functions of HDL that have recently attracted attention include anti-inflammatory and anti-oxidant activities. High antioxidant and anti-inflammatory activities of HDL are associated with protection from CVD.This review addresses the current state of knowledge regarding assays of HDL functions and their relationship to CVD. HDL as a therapeutic target is the new frontier with huge potential for positive public health implications.

Root parasitic plant Orobanche aegyptiaca and shoot parasitic plant Cuscuta australis obtained Brassicaceae-specific strictosidine synthase-like genes by horizontal gene transfer.

Science.gov (United States)

Zhang, Dale; Qi, Jinfeng; Yue, Jipei; Huang, Jinling; Sun, Ting; Li, Suoping; Wen, Jian-Fan; Hettenhausen, Christian; Wu, Jinsong; Wang, Lei; Zhuang, Huifu; Wu, Jianqiang; Sun, Guiling

2014-01-13

Besides gene duplication and de novo gene generation, horizontal gene transfer (HGT) is another important way of acquiring new genes. HGT may endow the recipients with novel phenotypic traits that are important for species evolution and adaption to new ecological niches. Parasitic systems expectedly allow the occurrence of HGT at relatively high frequencies due to their long-term physical contact. In plants, a number of HGT events have been reported between the organelles of parasites and the hosts, but HGT between host and parasite nuclear genomes has rarely been found. A thorough transcriptome screening revealed that a strictosidine synthase-like (SSL) gene in the root parasitic plant Orobanche aegyptiaca and the shoot parasitic plant Cuscuta australis showed much higher sequence similarities with those in Brassicaceae than with those in their close relatives, suggesting independent gene horizontal transfer events from Brassicaceae to these parasites. These findings were strongly supported by phylogenetic analysis and their identical unique amino acid residues and deletions. Intriguingly, the nucleus-located SSL genes in Brassicaceae belonged to a new member of SSL gene family, which were originated from gene duplication. The presence of introns indicated that the transfer occurred directly by DNA integration in both parasites. Furthermore, positive selection was detected in the foreign SSL gene in O. aegyptiaca but not in C. australis. The expression of the foreign SSL genes in these two parasitic plants was detected in multiple development stages and tissues, and the foreign SSL gene was induced after wounding treatment in C. australis stems. These data imply that the foreign genes may still retain certain functions in the recipient species. Our study strongly supports that parasitic plants can gain novel nuclear genes from distantly related host species by HGT and the foreign genes may execute certain functions in the new hosts.

Zoology: Invertebrates that Parasitize Invertebrates.

Science.gov (United States)

Giribet, Gonzalo

2016-07-11

The genome of an orthonectid, a group of highly modified parasitic invertebrates, is drastically reduced and compact, yet it shows the bilaterian gene toolkit. Phylogenetic analyses place the enigmatic orthonectids within Spiralia, although their exact placement remains uncertain. Copyright © 2016 Elsevier Ltd. All rights reserved.

Parasites, Plants, and People.

Science.gov (United States)

Johnson, Marion; Moore, Tony

2016-06-01

Anthelminthic resistance is acknowledged worldwide and is a major problem in Aotearoa New Zealand, thus alternative parasite management strategies are imperative. One Health is an initiative linking animal, human, and environmental health. Parasites, plants, and people illustrate the possibilities of providing diverse diets for stock thereby lowering parasite burdens, improving the cultural wellbeing of a local community, and protecting the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Workshop on high power ICH antenna designs for high density tokamaks

International Nuclear Information System (INIS)

Aamodt, R.E.

1990-01-01

A workshop in high power ICH antenna designs for high density tokamaks was held in Boulder, Colorado on January 31 through February 2, 1990. The purposes of the workshop were to: (1) review the data base relevant to the high power heating of high density tokamaks; (2) identify the important issues which need to be addressed in order to ensure the success of the ICRF programs on CIT and Alcator C-MOD; and (3) recommend approaches for resolving the issues in a timely realistic manner. Some specific performance goals for the antenna system define a successful design effort. Simply stated these goals are: couple the specified power per antenna into the desired ion species; produce no more than an acceptable level of rf auxiliary power induced impurities; and have a mechanical structure which safely survives the thermal, mechanical and radiation stresses in the relevant environment. These goals are intimately coupled and difficult tradeoffs between scientific and engineering constraints have to be made

Relativistic many-body theory of high density matter

International Nuclear Information System (INIS)

Chin, S.A.

1977-01-01

A fully relativistic quantum many-body theory is applied to the study of high-density matter. The latter is identified with the zero-temperature ground state of a system of interacting baryons. In accordance with the observed short-range repulsive and long-range attractive character of the nucleon--nucleon force, baryons are described as interacting with each other via a massive scalar and a massive vector meson exchange. In the Hartree approximation, the theory yields the same result as the mean-field theory, but with additional vacuum fluctuation corrections. The resultant equation of state for neutron matter is used to determine properties of neutron stars. The relativistic exchange energy, its corresponding single-particle excitation spectrum, and its effect on the neutron matter equation of state, are calculated. The correlation energy from summing the set of ring diagrams is derived directly from the energy-momentum tensor, with renormalization carried out by adding counterterms to the original Lagrangian and subtracting purely vacuum expectation values. Terms of order g 4 lng 2 are explicitly given. Effects of scalar-vector mixing are discussed. Collective modes corresponding to macroscopic density fluctuation are investigated. Two basic modes are found, a plasma-like mode and zero sound, with the latter dominant at high density. The stability and damping of these modes are studied. Last, the effect of vacuum polarization in high-density matter is examined

Allopatric speciation of Meteterakis (Heterakoidea: Heterakidae), a highly dispersible parasitic nematode, in the East Asian islands.

Science.gov (United States)

Sata, Naoya

2018-04-25

To clarify how the species diversity of highly dispersible parasites has developed, molecular phylogenetic analyses of Meteterakis spp., multi-host endoparasitic nematodes of reptiles and amphibians from the East Asian islands, were conducted. The results demonstrated the existence of two major clades, the J- and A-groups, with exclusive geographic ranges that are discordant with the host faunal province. However, diversification within the J-group was concordant with the host biogeography and suggested co-divergence of this group with vicariance of the host fauna. In contrast, the phylogenetic pattern within the A-group was discordant with host biogeography and implied diversification by repeated colonization. In addition, the mosaic distribution pattern of a J-group and an A-group species in the Japanese Archipelago, along with comparison of population genetic parameters and the genetic distance from their closest relatives, suggested the initial occurrence of a J-group lineage followed by exclusion in the western part of this region caused by invasion of an A-group lineage. Thus, the present study suggested that the species diversity of highly dispersible parasites including Meteterakis is formed not only by co-divergence with host faunal vicariance but also by peripatric speciation and exclusive interactions between species. Copyright © 2018 Elsevier B.V. All rights reserved.

The Evolution of Clutch Size in Hosts of Avian Brood Parasites.

Science.gov (United States)

Medina, Iliana; Langmore, Naomi E; Lanfear, Robert; Kokko, Hanna

2017-11-01

Coevolution with avian brood parasites shapes a range of traits in their hosts, including morphology, behavior, and breeding systems. Here we explore whether brood parasitism is also associated with the evolution of host clutch size. Several studies have proposed that hosts of highly virulent parasites could decrease the costs of parasitism by evolving a smaller clutch size, because hosts with smaller clutches will lose fewer progeny when their clutch is parasitized. We describe a model of the evolution of clutch size, which challenges this logic and shows instead that an increase in clutch size (or no change) should evolve in hosts. We test this prediction using a broad-scale comparative analysis to ask whether there are differences in clutch size within hosts and between hosts and nonhosts. Consistent with our model, this analysis revealed that host species do not have smaller clutches and that hosts that incur larger costs from raising a parasite lay larger clutches. We suggest that brood parasitism might be an influential factor in clutch-size evolution and could potentially select for the evolution of larger clutches in host species.

Pulse compression radar reflectometry for density measurements on fusion plasmas

Energy Technology Data Exchange (ETDEWEB)

Costley, A; Prentice, R [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Laviron, C [Compagnie Generale des Matieres Nucleaires (COGEMA), 78 - Velizy-Villacoublay (France); Prentice, R [Toulouse-3 Univ., 31 (France). Centre d` Etude Spatiale des Rayonnements

1994-07-01

On tokamaks and other toroidal machines, reflectometry is a very rapidly developing technique for density profile measurements, particularly near the edge. Its principle relies on the total reflection of an electromagnetic wave at a cutoff layer, where the critical density is reached and the local refractive index goes to zero. With the new fast frequency synthesizers now available, a method based on pulse compression radar is proposed for plasma reflectometry, overcoming the limitations of the previous reflectometry methods. The measurement can be made on a time-scale which is effectively very short relatively to the plasma fluctuations, and the very high reproducibility and stability of the source allows an absolute calibration of the waveguides to be made, which corrects for the effects of the parasitic reflections. 2 refs., 5 figs.

Variable kernel density estimation in high-dimensional feature spaces

CSIR Research Space (South Africa)

Van der Walt, Christiaan M

2017-02-01

Full Text Available Estimating the joint probability density function of a dataset is a central task in many machine learning applications. In this work we address the fundamental problem of kernel bandwidth estimation for variable kernel density estimation in high...

Zoonotic intestinal parasites of carnivores: A systematic review in Iran

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Shahabeddin Sarvi

2018-01-01

Full Text Available Aim: Parasitic infections, especially of the zoonotic-parasitic type, are the most important health, economic, and social problems in developing countries, including Iran. The aim of this study was to review systematically the available data on gastrointestinal parasites of carnivores in Iran and their ability to infect humans. Materials and Methods: Studies reporting intestinal parasites of carnivores were systematically collected from nine electronic English and Persian databases and Proceedings of Iranian parasitology and veterinary congresses published between 1997 and 2015. A total of 26 studies issued from 1997 to 2015 met the eligibility criteria. Results: The pooled proportion of intestinal parasites of carnivores was estimated as 80.4% (95% confidence interval=70.2-88.8%. The overall prevalence of gastrointestinal parasites in dogs, cats, foxes, and jackals were 57.89%, 90.62%, 89.17%, and 97.32%, respectively. Dipylidium caninum (20.45%, Toxocara spp. (18.81%, Taenia hydatigena (15.28%, Mesocestoides lineatus (11.83%, Echinococcus granulosus (10%, and Toxascaris leonina (8.69% were the most frequently observed parasites. Conclusion: High prevalence rates of zoonotic intestinal parasites of carnivores particularly Echinococcus spp. and Toxocara spp. increase the risk of acquiring zoonotic infections such as cystic hydatid, alveolar cysts, and visceral or ocular larva migrants in Iranian people. Therefore, it is essential for public health centers to develop more effective control strategies to decrease infections rates in carnivores' populations.

Zoonotic intestinal parasites of carnivores: A systematic review in Iran

Science.gov (United States)

Sarvi, Shahabeddin; Daryani, Ahmad; Sharif, Mehdi; Rahimi, Mohammad Taghi; Kohansal, Mohammad Hasan; Mirshafiee, Siavash; Siyadatpanah, Abolghasem; Hosseini, Seyed-Abdollah; Gholami, Shirzad

2018-01-01

Aim: Parasitic infections, especially of the zoonotic-parasitic type, are the most important health, economic, and social problems in developing countries, including Iran. The aim of this study was to review systematically the available data on gastrointestinal parasites of carnivores in Iran and their ability to infect humans. Materials and Methods: Studies reporting intestinal parasites of carnivores were systematically collected from nine electronic English and Persian databases and Proceedings of Iranian parasitology and veterinary congresses published between 1997 and 2015. A total of 26 studies issued from 1997 to 2015 met the eligibility criteria. Results: The pooled proportion of intestinal parasites of carnivores was estimated as 80.4% (95% confidence interval=70.2-88.8%). The overall prevalence of gastrointestinal parasites in dogs, cats, foxes, and jackals were 57.89%, 90.62%, 89.17%, and 97.32%, respectively. Dipylidium caninum (20.45%), Toxocara spp. (18.81%), Taenia hydatigena (15.28%), Mesocestoides lineatus (11.83%), Echinococcus granulosus (10%), and Toxascaris leonina (8.69%) were the most frequently observed parasites. Conclusion: High prevalence rates of zoonotic intestinal parasites of carnivores particularly Echinococcus spp. and Toxocara spp. increase the risk of acquiring zoonotic infections such as cystic hydatid, alveolar cysts, and visceral or ocular larva migrants in Iranian people. Therefore, it is essential for public health centers to develop more effective control strategies to decrease infections rates in carnivores’ populations. PMID:29479158

Highly Compressed Ion Beams for High Energy Density Science

CERN Document Server

Friedman, Alex; Briggs, Richard J; Callahan, Debra; Caporaso, George; Celata, C M; Davidson, Ronald C; Faltens, Andy; Grant-Logan, B; Grisham, Larry; Grote, D P; Henestroza, Enrique; Kaganovich, Igor D; Lee, Edward; Lee, Richard; Leitner, Matthaeus; Nelson, Scott D; Olson, Craig; Penn, Gregory; Reginato, Lou; Renk, Tim; Rose, David; Sessler, Andrew M; Staples, John W; Tabak, Max; Thoma, Carsten H; Waldron, William; Welch, Dale; Wurtele, Jonathan; Yu, Simon

2005-01-01

The Heavy Ion Fusion Virtual National Laboratory (HIF-VNL) is developing the intense ion beams needed to drive matter to the High Energy Density (HED) regimes required for Inertial Fusion Energy (IFE) and other applications. An interim goal is a facility for Warm Dense Matter (WDM) studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target "foils," which may in fact be foams or "steel wool" with mean densities 1% to 100% of solid. This approach complements that being pursued at GSI, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the requirements for warm dense matter experiments, and describe suitable accelerator concepts, including novel broadband traveling wave pulse-line, drift-tube linac, RF, and single-gap approa...

A high energy density relaxor antiferroelectric pulsed capacitor dielectric

Energy Technology Data Exchange (ETDEWEB)

Jo, Hwan Ryul; Lynch, Christopher S. [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles (UCLA), Los Angeles, California 90095 (United States)

2016-01-14

Pulsed capacitors require high energy density and low loss, properties that can be realized through selection of composition. Ceramic (Pb{sub 0.88}La{sub 0.08})(Zr{sub 0.91}Ti{sub 0.09})O{sub 3} was found to be an ideal candidate. La{sup 3+} doping and excess PbO were used to produce relaxor antiferroelectric behavior with slim and slanted hysteresis loops to reduce the dielectric hysteresis loss, to increase the dielectric strength, and to increase the discharge energy density. The discharge energy density of this composition was found to be 3.04 J/cm{sup 3} with applied electric field of 170 kV/cm, and the energy efficiency, defined as the ratio of the discharge energy density to the charging energy density, was 0.920. This high efficiency reduces the heat generated under cyclic loading and improves the reliability. The properties were observed to degrade some with temperature increase above 80 °C. Repeated electric field cycles up to 10 000 cycles were applied to the specimen with no observed performance degradation.

Enhanced transmission of drug-resistant parasites to mosquitoes following drug treatment in rodent malaria.

Directory of Open Access Journals (Sweden)

Andrew S Bell

Full Text Available The evolution of drug resistant Plasmodium parasites is a major challenge to effective malaria control. In theory, competitive interactions between sensitive parasites and resistant parasites within infections are a major determinant of the rate at which parasite evolution undermines drug efficacy. Competitive suppression of resistant parasites in untreated hosts slows the spread of resistance; competitive release following treatment enhances it. Here we report that for the murine model Plasmodium chabaudi, co-infection with drug-sensitive parasites can prevent the transmission of initially rare resistant parasites to mosquitoes. Removal of drug-sensitive parasites following chemotherapy enabled resistant parasites to transmit to mosquitoes as successfully as sensitive parasites in the absence of treatment. We also show that the genetic composition of gametocyte populations in host venous blood accurately reflects the genetic composition of gametocytes taken up by mosquitoes. Our data demonstrate that, at least for this mouse model, aggressive chemotherapy leads to very effective transmission of highly resistant parasites that are present in an infection, the very parasites which undermine the long term efficacy of front-line drugs.

THE INCIDENCE OF PARASITIC DISEASES IN LIVESTOCK IN BALI

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N. A. Suratma

2012-09-01

Full Text Available The population of livestock in Bali has continuously increased from year to year. However, some problems are encountered with parasitic infections in livestock. Parasitic infections may be caused by worms, protozoa or ectoparasites. In cattle, the most common infections are those caused by Oesophagostomum sp, Ostertagia sp, Haemonchus sp, Mecistocirrus sp, and Cooperia sp which is the most dominant. Neoascaris vitulorum was reported to be as high as 29.1% in calves. Fascioliasis in cattle was found highly prevalent, between 34.9 to 56.7% and was caused by Fasciola gigantica. Also Paramphistomum infection was reported to be highly prevalent (50.1%. In addition, Boophilus microplus was recorded as high as 36.9%. In goat and sheep, the incidence of Haemonchus contortus was 27.7% and 53.6% respectively. Infestation of Paramphistomum sp in goat was 9.27%. Concerning ectoparasites, Sarcoptes scabiei was reported to be the cause of death of 67% of young goats and up to 11% of older gats in Br. Penginuman, Gilimanuk Negara. Parasitic infections in pigs were caused by Cysticercus tenuicollis (11% and Ascaris suum (24.2% and 21.1% showed Metastrongylus apri and also Sarcoptes scabiei was reported to be the cause of skin disease in pigs. In poultry, parasitic infection were caused by Raillietina (96%, Heterakis gallinae (66.7%, Capillaria sp (6.6%, Ascardia galli (56.7%, Oxyspirura mansoni (50%, Acuaria spiralis (13.3% and Syngamus trachea (3.3%. Multiple infections are common.

Host-Parasite Interactions and Purifying Selection in a Microsporidian Parasite of Honey Bees.

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Qiang Huang

Full Text Available To clarify the mechanisms of Nosema ceranae parasitism, we deep-sequenced both honey bee host and parasite mRNAs throughout a complete 6-day infection cycle. By time-series analysis, 1122 parasite genes were significantly differently expressed during the reproduction cycle, clustering into 4 expression patterns. We found reactive mitochondrial oxygen species modulator 1 of the host to be significantly down regulated during the entire infection period. Our data support the hypothesis that apoptosis of honey bee cells was suppressed during infection. We further analyzed genome-wide genetic diversity of this parasite by comparing samples collected from the same site in 2007 and 2013. The number of SNP positions per gene and the proportion of non-synonymous substitutions per gene were significantly reduced over this time period, suggesting purifying selection on the parasite genome and supporting the hypothesis that a subset of N. ceranae strains might be dominating infection.

Female field crickets incur increased parasitism risk when near preferred song.

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Cassandra M Martin

2010-03-01

Full Text Available Female animals often prefer males with conspicuous traits because these males provide direct or indirect benefits. Conspicuous male traits, however, can attract predators. This not only increases the risk of predation for conspicuous males but also for the females that prefer them. In the variable field cricket, Gryllus lineaticeps, males that produce preferred song types provide females with greater material benefits, but they are also more likely to attract lethal parasitoid flies. First, we conducted a field experiment that tested the hypothesis that females have a greater risk of fly parasitism when in association with preferred high chirp rate males. Females were nearly twice as likely to be parasitized when caged with high chirp rate song than when caged with low chirp rate song. Females may thus be forced to trade off the quality of the benefits they receive from mating with preferred males and the risk of being killed by a predator when near these males. Second, we assessed female parasitism rates in a natural population. Up to 6% of the females were parasitized in field samples. Because the females we collected could have become parasitized had they not been collected, this provides a minimum estimate of the female parasitism rate in the field. In a laboratory study, we found no difference in the proportion of time parasitized and unparasitized females spent hiding under shelters; thus, differences in activity patterns do not appear to have biased our estimate of female parasitism rates. Overall, our results suggest that female association costs have the potential to shape the evolution of female mating preferences.

Emergence of ratio-dependent and predator-dependent functional responses for pollination mutualism and seed parasitism

Science.gov (United States)

DeAngelis, Donald L.; Holland, J. Nathaniel

2006-01-01

Prey (N) dependence [g(N)], predator (P) dependence [g(P) or g(N,P)], and ratio dependence [f(P/N)] are often seen as contrasting forms of the predator's functional response describing predator consumption rates on prey resources in predator–prey and parasitoid–host interactions. Analogously, prey-, predator-, and ratio-dependent functional responses are apparently alternative functional responses for other types of consumer–resource interactions. These include, for example, the fraction of flowers pollinated or seeds parasitized in pollination (pre-dispersal) seed-parasitism mutualisms, such as those between fig wasps and fig trees or yucca moths and yucca plants. Here we examine the appropriate functional responses for how the fraction of flowers pollinated and seeds parasitized vary with the density of pollinators (predator dependence) or the ratio of pollinator and flower densities (ratio dependence). We show that both types of functional responses can emerge from minor, but biologically important variations on a single model. An individual-based model was first used to describe plant–pollinator interactions. Conditional upon on whether the number of flowers visited by the pollinator was limited by factors other than search time (e.g., by the number of eggs it had to lay, if it was also a seed parasite), and on whether the pollinator could directly find flowers on a plant, or had to search, the simulation results lead to either a predator-dependent or a ratio-dependent functional response. An analytic model was then used to show mathematically how these two cases can arise.

Unique physiology of host-parasite interactions in microsporidia infections.

Science.gov (United States)

Williams, Bryony A P

2009-11-01

Microsporidia are intracellular parasites of all major animal lineages and have a described diversity of over 1200 species and an actual diversity that is estimated to be much higher. They are important pathogens of mammals, and are now one of the most common infections among immunocompromised humans. Although related to fungi, microsporidia are atypical in genomic biology, cell structure and infection mechanism. Host cell infection involves the rapid expulsion of a polar tube from a dormant spore to pierce the host cell membrane and allow the direct transfer of the spore contents into the host cell cytoplasm. This intimate relationship between parasite and host is unique. It allows the microsporidia to be highly exploitative of the host cell environment and cause such diverse effects as the induction of hypertrophied cells to harbour prolific spore development, host sex ratio distortion and host cell organelle and microtubule reorganization. Genome sequencing has revealed that microsporidia have achieved this high level of parasite sophistication with radically reduced proteomes and with many typical eukaryotic pathways pared-down to what appear to be minimal functional units. These traits make microsporidia intriguing model systems for understanding the extremes of reductive parasite evolution and host cell manipulation.

PARASITES OF FISH

Science.gov (United States)

The intent of this chapter is to describe the parasites of importance to fishes maintained and used in laboratory settings. In contrast to the frist edition, the focus will be only on those parasites that pose a serious threat to or are common in fishes held in these confined en...

Parasitismo de traça-das-crucíferas por Oomyzus sokolowskii Parasitism of diamondback moth by Oomyzus sokolowskii

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Christian Sherley Araújo da Silva-Torres

2010-07-01

Full Text Available O objetivo deste trabalho foi avaliar a capacidade de parasitismo do parasitoide larval-pupal Oomyzus sokolowskii, submetido a diferentes densidades do hospedeiro traça-das-crucíferas (Plutella xylostella, em laboratório, casa telada e campo. Em laboratório e campo, O. sokolowskii foi exposto às densidades de 2, 4, 8 e 16 lagartas. Em laboratório, empregaram-se recipientes de 300 mL e, em campo, plantas de couve foram confinadas em gaiolas de organza (30x50 cm. Em casa telada, foram utilizadas microparcelas compostas por seis plantas de repolho infestadas com 25, 50, 85 ou 100 lagartas. O número de lagartas parasitadas aumentou de acordo com a densidade do hospedeiro e variou de 1,7 a 10,4, em laboratório, e de 0,61 a 7,0, em campo. Em casa telada, a maior taxa de parasitismo foi observada nas microparcelas com densidades mais elevadas do hospedeiro. O tempo de exposição aos parasitoides proporcionou maior taxa de parasitismo após 72 horas (24 horas, 52,4% e 72 horas, 80,7% independentemente da densidade. Oomyzus sokolowskii responde positivamente ao incremento na densidade de P. xylostella, embora a taxa de parasitismo permaneça constante independentemente da disponibilidade do hospedeiro.The objective of this work was to evaluate the parasitism capacity of the larval-pupal parasitoid Oomyzus sokolowskii submitted to different densities of the host diamondback moth, Plutella xylostella, in the laboratory, greenhouse and field. In the laboratory and in the field, O. sokolowskii was exposed to densities of 2, 4, 8 or 16 larvae. In the laboratory, 300 mL recipient were used, and in the field kale plants were placed in cages (30x50 cm. In the greenhouse, microparcels consisted of six cabbage plants each infested with 25, 50, 85 or 100 larvae. The number of parasitized larvae increased with host density and varied from 1.7 to 10.4 (laboratory and from 0.61 to 7.0 (field. In the greenhouse, parasitism rate was higher in microparcels with

Reduced helminth parasitism in the introduced bank vole (Myodes glareolus: More parasites lost than gained

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Karen C. Loxton

2016-08-01

Full Text Available Introduced species are often less parasitised compared to their native counterparts and to ecologically similar hosts in the new environment. Reduced parasitism may come about due to both the loss of original parasites and low acquisition of novel parasites. In this study we investigated the intestinal helminth parasites of the introduced bank vole (Myodes glareolus in Ireland. Results were compared to data from other European studies and to the intestinal helminth fauna of an ecologically similar native rodent in Ireland, the wood mouse (Apodemus sylvaticus. The helminth fauna of introduced bank voles exhibited low diversity with only 3 species recovered: Aspiculuris tianjinensis; Aonchotheca murissylvatici and Taenia martis larvae. In particular, no adult parasites with indirect life-cycles were found in bank voles suggesting that indirectly transmitted parasites are less likely to establish in invasive hosts. Also, the results of this study add support to the enemy release hypothesis.

Parasites and immunotherapy: with or against?

Science.gov (United States)

Yousofi Darani, Hossein; Yousefi, Morteza; Safari, Marzieh; Jafari, Rasool

2016-06-01

Immunotherapy is a sort of therapy in which antibody or antigen administrates to the patient in order to treat or reduce the severity of complications of disease. This kind of treatment practiced in a wide variety of diseases including infectious diseases, autoimmune disorders, cancers and allergy. Successful and unsuccessful immunotherapeutic strategies have been practiced in variety of parasitic infections. On the other hand parasites or parasite antigens have also been considered for immunotherapy against other diseases such as cancer, asthma and multiple sclerosis. In this paper immunotherapy against common parasitic infections, and also immunotherapy of cancer, asthma and multiple sclerosis with parasites or parasite antigens have been reviewed.

High density UO2 powder preparation for HWR fuel

International Nuclear Information System (INIS)

Hwang, S. T.; Chang, I. S.; Choi, Y. D.; Cho, B. R.; Kwon, S. W.; Kim, B. H.; Moon, B. H.; Kim, S. D.; Phyu, K. M.; Lee, K. A.

1992-01-01

The objective of this project is to study on the preparation of method high density UO 2 powder for HWR Fuel. Accordingly, it is necessary to character ize the AUC processed UO 2 powder and to search method for the preparation of high density UO 2 powder for HWR Fuel. Therefore, it is expected that the results of this study can effect the producing of AUC processed UO 2 powder having sinterability. (Author)

Parasitic worms: how many really?

Science.gov (United States)

Strona, Giovanni; Fattorini, Simone

2014-04-01

Accumulation curves are useful tools to estimate species diversity. Here we argue that they can also be used in the study of global parasite species richness. Although this basic idea is not completely new, our approach differs from the previous ones as it treats each host species as an independent sample. We show that randomly resampling host-parasite records from the existing databases makes it possible to empirically model the relationship between the number of investigated host species, and the corresponding number of parasite species retrieved from those hosts. This method was tested on 21 inclusive lists of parasitic worms occurring on vertebrate hosts. All of the obtained models conform well to a power law curve. These curves were then used to estimate global parasite species richness. Results obtained with the new method suggest that current predictions are likely to severely overestimate parasite diversity. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Electrical and mechanical properties of highly elongated high density polyethylene as cryogenic insulation materials

International Nuclear Information System (INIS)

Yoshino, Katsumi; Park, Dae-Hee; Miyata, Kiyomi; Yamaoka, Hitoshi; Itoh, Minoru; Ichihara, Syouji.

1989-01-01

Electrical and mechanical properties of highly elongated high density polyethylene were investigated in the temperature range between 4.2 K and 400 K from a viewpoint of electrical insulation at low temperature and the following properties have been clarified. (1) The electrical conductivity of samples decreases with increasing draw ratio, and also decreases at cryogenic temperature. (2) Breakdown strength of highly elongated sample is similar to that of non-elongated sample. It is nearby temperature independent below 300 K but at higher temperature it falls steeply. (3) Mechanical breakdown stress and elastic modulus of high density polyethylene increase with increasing draw ratio. Their values at liquid nitrogen temperature are much higher than that at room temperature. On the other hand, strains decreases at liquid nitrogen temperature. (4) Break of the sample develops in the direction of 45deg from the direction of stress both at room temperature and at cryogenic temperature. (5) The characteristic of mechanical breakdown at liquid nitrogen temperature can be explained by a brittleness fracture process. (6) Toughness of high density polyethylene increases with increasing draw ratio until draw ratio of 5, and it decreased, and increase at higher draw ratio. However at extremely high draw ratio of 10 it again increases. These findings clearly indicate that highly elongated high density polyethylene has good electrical and mechanical properties at cryogenic temperature and can be used as the insulating materials at cryogenic temperature. (author)

Gastrointestinal parasites in captive and free-ranging Cebus albifrons in the Western Amazon, Ecuador

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Sarah Martin-Solano

2017-12-01

Full Text Available Currently, there is a lack of surveys that report the occurrence of gastrointestinal parasites in the white-headed capuchin monkey (Cebus albifrons. We therefore assessed the presence and richness (= number of different parasite genera of parasites in C. albifrons in wildlife refuges (n = 11 and in a free-ranging group near a human village (n = 15 in the Ecuadorian Amazon. In the 78 samples collected (median of 3 samples per animal, we identified a total of 6 genera of gastrointestinal parasites, representing protozoa, nematodes, acanthocephalans and cestodes. We observed a high prevalence (84% across the 26 individuals, with the most prevalent parasite being Strongyloides sp. (76.9%, followed by Hymenolepis sp. (38.5% and Prosthenorchis elegans (11.5%. We found Entamoeba histolytica/dispar/moskovskii/nuttalli and Capillaria sp. in only a minority of the animals (3.8%. In addition, we observed unidentified strongyles in approximately one-third of the animals (34.6%. We found a total of 6 parasite genera for the adult age group, which showed higher parasite richness than the subadult age group (5 and the juvenile age group (3. Faecal egg/cyst counts were not significantly different between captive and free-ranging individuals or between sexes or age groups. The free-ranging group had a higher prevalence than the captive group; however, this difference was not significant. The only genus common to captive and free-ranging individuals was Strongyloides sp. The high prevalence of gastrointestinal parasites and the presence of Strongyloides in both populations support results from previous studies in Cebus species. This high prevalence could be related to the high degree of humidity in the region. For the free-ranging group, additional studies are required to gain insights into the differences in parasite prevalence and intensity between age and sex groups. Additionally, our study demonstrated that a serial sampling of each individual increases

Host-parasite interactions and ecology of the malaria parasite-a bioinformatics approach.

Science.gov (United States)

Izak, Dariusz; Klim, Joanna; Kaczanowski, Szymon

2018-04-25

Malaria remains one of the highest mortality infectious diseases. Malaria is caused by parasites from the genus Plasmodium. Most deaths are caused by infections involving Plasmodium falciparum, which has a complex life cycle. Malaria parasites are extremely well adapted for interactions with their host and their host's immune system and are able to suppress the human immune system, erase immunological memory and rapidly alter exposed antigens. Owing to this rapid evolution, parasites develop drug resistance and express novel forms of antigenic proteins that are not recognized by the host immune system. There is an emerging need for novel interventions, including novel drugs and vaccines. Designing novel therapies requires knowledge about host-parasite interactions, which is still limited. However, significant progress has recently been achieved in this field through the application of bioinformatics analysis of parasite genome sequences. In this review, we describe the main achievements in 'malarial' bioinformatics and provide examples of successful applications of protein sequence analysis. These examples include the prediction of protein functions based on homology and the prediction of protein surface localization via domain and motif analysis. Additionally, we describe PlasmoDB, a database that stores accumulated experimental data. This tool allows data mining of the stored information and will play an important role in the development of malaria science. Finally, we illustrate the application of bioinformatics in the development of population genetics research on malaria parasites, an approach referred to as reverse ecology.

Extreme states of matter high energy density physics

CERN Document Server

Fortov, Vladimir E

2016-01-01

With its many beautiful colour pictures, this book gives fascinating insights into the unusual forms and behaviour of matter under extremely high pressures and temperatures. These extreme states are generated, among other things, by strong shock, detonation and electric explosion waves, dense laser beams,electron and ion beams, hypersonic entry of spacecraft into dense atmospheres of planets, and in many other situations characterized by extremely high pressures and temperatures.Written by one of the world's foremost experts on the topic, this book will inform and fascinate all scientists dealing with materials properties and physics, and also serve as an excellent introduction to plasma-, shock-wave and high-energy-density physics for students and newcomers seeking an overview. This second edition is thoroughly revised and expanded, in particular with new material on high energy-density physics, nuclear explosions and other nuclear transformation processes.

Supernovae and high density nuclear matter

Energy Technology Data Exchange (ETDEWEB)

Kahana, S.

1986-01-01

The role of the nuclear equation of state (EOS) in producing prompt supernova explosions is examined. Results of calculations of Baron, Cooperstein, and Kahana incorporating general relativity and a new high density EOS are presented, and the relevance of these calculations to laboratory experiments with heavy ions considered. 31 refs., 6 figs., 2 tabs.

Supernovae and high density nuclear matter

International Nuclear Information System (INIS)

Kahana, S.

1986-01-01

The role of the nuclear equation of state (EOS) in producing prompt supernova explosions is examined. Results of calculations of Baron, Cooperstein, and Kahana incorporating general relativity and a new high density EOS are presented, and the relevance of these calculations to laboratory experiments with heavy ions considered. 31 refs., 6 figs., 2 tabs

ADX: a high field, high power density, Advanced Divertor test eXperiment

Science.gov (United States)

Vieira, R.; Labombard, B.; Marmar, E.; Irby, J.; Shiraiwa, S.; Terry, J.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; ADX Team

2014-10-01

The MIT PSFC and collaborators are proposing an advanced divertor experiment (ADX) - a tokamak specifically designed to address critical gaps in the world fusion research program on the pathway to FNSF/DEMO. This high field (6.5 tesla, 1.5 MA), high power density (P/S ~ 1.5 MW/m2) facility would utilize Alcator magnet technology to test innovative divertor concepts for next-step DT fusion devices (FNSF, DEMO) at reactor-level boundary plasma pressures and parallel heat flux densities while producing high performance core plasma conditions. The experimental platform would also test advanced lower hybrid current drive (LHCD) and ion-cyclotron range of frequency (ICRF) actuators and wave physics at the plasma densities and magnetic field strengths of a DEMO, with the unique ability to deploy launcher structures both on the low-magnetic-field side and the high-field side - a location where energetic plasma-material interactions can be controlled and wave physics is most favorable for efficient current drive, heating and flow drive. This innovative experiment would perform plasma science and technology R&D necessary to inform the conceptual development and accelerate the readiness-for-deployment of FNSF/DEMO - in a timely manner, on a cost-effective research platform. Supported by DE-FC02-99ER54512.

Data from: Not all are free-living: high-throughput DNA metabarcoding reveals a diverse community of protists parasitizing soil metazoa

NARCIS (Netherlands)

Geisen, Stefan; Laros, I.; Vizcaino, A.; Bonkowski, M.; Groot, de G.A.

2015-01-01

Protists, the most diverse eukaryotes, are largely considered to be free-living bacterivores, but vast numbers of taxa are known to parasitize plants or animals. High-throughput sequencing (HTS) approaches now commonly replace cultivation-based approaches in studying soil protists, but insights into

Numerical design and analysis of parasitic mode oscillations for 95 GHz gyrotron beam tunnel

Science.gov (United States)

Kumar, Nitin; Singh, Udaybir; Yadav, Vivek; Kumar, Anil; Sinha, A. K.

2013-05-01

The beam tunnel, equipped with the high lossy ceramics, is designed for 95 GHz gyrotron. The geometry of the beam tunnel is optimized considering the maximum RF absorption (ideally 100%) and the suppression of parasitic oscillations. The excitation of parasitic modes is a concerning problem for high frequency, high power gyrotrons. Considering the problem of parasitic mode excitation in beam tunnel, a detail analysis is performed for the suppression of these kinds of modes. Trajectory code EGUN and CST Microwave Studio are used for the simulations of electron beam trajectory and electromagnetic analysis, respectively.

Leishmania development in sand flies: parasite-vector interactions overview.

Science.gov (United States)

Dostálová, Anna; Volf, Petr

2012-12-03

Leishmaniases are vector-borne parasitic diseases with 0.9 - 1.4 million new human cases each year worldwide. In the vectorial part of the life-cycle, Leishmania development is confined to the digestive tract. During the first few days after blood feeding, natural barriers to Leishmania development include secreted proteolytic enzymes, the peritrophic matrix surrounding the ingested blood meal and sand fly immune reactions. As the blood digestion proceeds, parasites need to bind to the midgut epithelium to avoid being excreted with the blood remnant. This binding is strictly stage-dependent as it is a property of nectomonad and leptomonad forms only. While the attachment in specific vectors (P. papatasi, P. duboscqi and P. sergenti) involves lipophosphoglycan (LPG), this Leishmania molecule is not required for parasite attachment in other sand fly species experimentally permissive for various Leishmania. During late-stage infections, large numbers of parasites accumulate in the anterior midgut and produce filamentous proteophosphoglycan creating a gel-like plug physically obstructing the gut. The parasites attached to the stomodeal valve cause damage to the chitin lining and epithelial cells of the valve, interfering with its function and facilitating reflux of parasites from the midgut. Transformation to metacyclic stages highly infective for the vertebrate host is the other prerequisite for effective transmission. Here, we review the current state of knowledge of molecular interactions occurring in all these distinct phases of parasite colonization of the sand fly gut, highlighting recent discoveries in the field.

Immunity to parasitic infection

National Research Council Canada - National Science Library

Lamb, Tracey J

2012-01-01

.... Often endemic in developing countries many parasitic diseases are neglected in terms of research funding and much remains to be understood about parasites and the interactions they have with the immune system...

Immunity to parasitic infection

National Research Council Canada - National Science Library

Lamb, Tracey J

2012-01-01

... may be manipulated to develop therapeutic interventions against parasitic infection. For easy reference, the most commonly studied parasites are examined in individual chapters written by investigators at the forefront of their field...

Food-borne human parasitic pathogens associated with household cockroaches and houseflies in Nigeria

Directory of Open Access Journals (Sweden)

Oyetunde T. Oyeyemi

2016-03-01

Full Text Available Cockroaches and houseflies pose significant public health threat owning to their ability to mechanically transmit human intestinal parasites and other disease-causing microorganisms. This study aims at assessing the vectoral capacity of cockroaches and houseflies in the transmission of human intestinal parasites. Intestinal parasite external surface contamination of 130 cockroaches and 150 houseflies caught within dwelling places in Ilishan-Remo town, Ogun State, Nigeria was determined. Cockroaches (six parasite species were more contaminated than houseflies (four parasite species. The most prevalent parasites were Trichuris trichiura (74.0% and hookworm (63.0% in houseflies and cockroaches respectively. There were significant differences in the prevalence of hookworm, T. trichiura and Taenia spp. isolated from cockroaches and houseflies (P < 0.05. There is high contamination of human intestinal parasites in cockroaches and houseflies in human dwelling places in the study area, thus they have the ability to transmit these parasites to unkempt food materials.

9 CFR 381.88 - Parasites.

Science.gov (United States)

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Parasites. 381.88 Section 381.88 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE AGENCY... § 381.88 Parasites. Organs or other parts of carcasses which are found to be infested with parasites, or...

In vitro leukocyte response of three-spined sticklebacks (Gasterosteus aculeatus) to helminth parasite antigens.

Science.gov (United States)

Franke, Frederik; Rahn, Anna K; Dittmar, Janine; Erin, Noémie; Rieger, Jennifer K; Haase, David; Samonte-Padilla, Irene E; Lange, Joseph; Jakobsen, Per J; Hermida, Miguel; Fernández, Carlos; Kurtz, Joachim; Bakker, Theo C M; Reusch, Thorsten B H; Kalbe, Martin; Scharsack, Jörn P

2014-01-01

Helminth parasites of teleost fish have evolved strategies to evade and manipulate the immune responses of their hosts. Responsiveness of fish host immunity to helminth antigens may therefore vary depending on the degree of host-parasite counter-adaptation. Generalist parasites, infective for a number of host species, might be unable to adapt optimally to the immune system of a certain host species, while specialist parasites might display high levels of adaptation to a particular host species. The degree of adaptations may further differ between sympatric and allopatric host-parasite combinations. Here, we test these hypotheses by in vitro exposure of head kidney leukocytes from three-spined sticklebacks (Gasterosteus aculeatus) to antigens from parasites with a broad fish host range (Diplostomum pseudospathaceum, Triaenophorus nodulosus), a specific fish parasite of cyprinids (Ligula intestinalis) and parasites highly specific only to a single fish species as second intermediate host (Schistocephalus pungitii, which does not infect G. aculeatus, and Schistocephalus solidus, infecting G. aculeatus). In vitro responses of stickleback leukocytes to S. solidus antigens from six European populations, with S. solidus prevalence from aculeatus to a G. aculeatus-infecting species. Generalist parasites seem to maintain their ability to infect different host species at the costs of relatively higher immunogenicity compared to specialist parasites. In a comparison of sympatric and allopatric combinations of stickleback leukocytes and antigens from S. solidus, magnitudes of in vitro responses were dependent on the prevalence of the parasite in the population of origin, rather than on sympatry. Antigens from Norwegian (prevalence 30-50%) and Spanish (40-66%) S. solidus induced generally higher in vitro responses compared to S. solidus from two German (<1%) populations. Likewise, leukocytes from stickleback populations with a high S. solidus prevalence showed

Plasmodial Hsp70s are functionally adapted to the malaria parasite life cycle

Directory of Open Access Journals (Sweden)

Jude M Przyborski

2015-06-01

Full Text Available The human malaria parasite, Plasmodium falciparum, encodes a minimal complement of six heat shock protein 70s (PfHSP70s, some of which are highly expressed and are thought to play an important role in the survival and pathology of the parasite. In addition to canonical features of molecular chaperones, these HSP70s possess properties that reflect functional adaptation to a parasitic life style, including resistance to thermal insult during fever periods and host-parasite interactions. The parasite even exports an HSP70 to the host cell where it is likely to be involved in host cell modification. This review focuses on the features of the PfHSP70s, particularly with respect to their adaptation to the malaria parasite life cycle.

Parasite dispersal risk tolerance is mediated by its reproductive value.

Science.gov (United States)

Nolan, Maxcy P; Delaplane, Keith S

2017-10-01

Parasite dispersal theory draws heavily upon epidemiological SIR models in which host status (susceptible (S), infected (I), or recovered (R)) is used to study parasite dispersal evolution. In contrast to these extrinsically host-centric drivers, in this study we focus on an intrinsic driver, the parasite's reproductive value (predicted future offspring) as a regulator of the extent to which the individual will engage in risky dispersal behaviour. As a model system we use the honeybee Apis mellifera and its ectoparasite, the mite Varroa destructor . Mite reproduction happens exclusively inside cells of bee brood, and newly emerged fecund mites may parasitize either a homocolonial brood cell (low risk dispersal) or emigrate to a new bee colony via phoretic attachment to mature forager bees (high risk dispersal). In an empirical bioassay, prepartum mites (high reproductive value) and postpartum mites (low reproductive value) were offered a choice of newly emerged homocolonial worker bees (low risk), homocolonial pollen forager bees (high risk), or heterocolonial pollen foragers (high risk). A preference for newly emerged bees was earlier and more strongly sustained among prepartum mites. This suggests comparatively greater dispersal risk tolerance among postpartum mites with lower reproductive value. A dangerous bid for dispersal may be adaptive if the individual has already successfully reproduced and the rewards for successful dispersal are sufficiently large.

Parasitic infections of the external eye.

Science.gov (United States)

Pahuja, Shivani; Puranik, Charuta; Jelliti, Bechir; Khairallah, Moncef; Sangwan, Virender S

2013-08-01

To review the published literature on parasitic infections of external eye. Published articles and case reports on parasitic infections of external eye were reviewed and relevant information was collected. Parasitic infections of the eye are rare. However, being more commonly seen in developing nations, they require active measures for screening, diagnosis, and therapy. Parasites of importance causing external ocular disease are protozoan parasites, such as Leishmania; metazoans, such as nematodes (roundworms), cestodes (tapeworms), and trematodes (flatworms); or ectoparasites, such as Phthirus pubis and Demodex.

High density plasmas formation in Inertial Confinement Fusion and Astrophysics

International Nuclear Information System (INIS)

Martinez-Val, J. M.; Minguez, E.; Velarde, P.; Perlado, J. M.; Velarde, G.; Bravo, E.; Eliezer, S.; Florido, R.; Garcia Rubiano, J.; Garcia-Senz, D.; Gil de la Fe, J. M.; Leon, P. T.; Martel, P.; Ogando, F.; Piera, M.; Relano, A.; Rodriguez, R.; Garcia, C.; Gonzalez, E.; Lachaise, M.; Oliva, E.

2005-01-01

In inertially confined fusion (ICF), high densities are required to obtain high gains. In Fast Ignition, a high density, low temperature plasma can be obtained during the compression. If the final temperature reached is low enough, the electrons of the plasma can be degenerate. In degenerate plasmas. Bremsstrahlung emission is strongly suppressed an ignition temperature becomes lower than in classical plasmas, which offers a new design window for ICF. The main difficulty of degenerate plasmas in the compression energy needed for high densities. Besides that, the low specific heat of degenerate electrons (as compared to classical values) is also a problem because of the rapid heating of the plasma. Fluid dynamic evolution of supernovae remnants is a very interesting problem in order to predict the thermodynamical conditions achieved in their collision regions. Those conditions have a strong influence in the emission of light and therefore the detection of such events. A laboratory scale system has been designed reproducing the fluid dynamic field in high energy experiments. The evolution of the laboratory system has been calculated with ARWEN code, 2D Radiation CFD that works with Adaptive Mesh Refinement. Results are compared with simulations on the original system obtained with a 3D SPH astrophysical code. New phenomena at the collision plane and scaling of the laboratory magnitudes will be described. Atomic physics for high density plasmas has been studied with participation in experiments to obtain laser produced high density plasmas under NLTE conditions, carried out at LULI. A code, ATOM3R, has been developed which solves rate equations for optically thin plasmas as well as for homogeneous optically thick plasmas making use of escape factors. New improvements in ATOM3R are been done to calculate level populations and opacities for non homogeneous thick plasmas in NLTE, with emphasis in He and H lines for high density plasma diagnosis. Analytical expression

The bigger, the better? Volume measurements of parasites and hosts: Parasitic barnacles (Cirripedia, Rhizocephala and their decapod hosts.

Directory of Open Access Journals (Sweden)

Christina Nagler

Full Text Available Rhizocephala, a group of parasitic castrators of other crustaceans, shows remarkable morphological adaptations to their lifestyle. The adult female parasite consists of a body that can be differentiated into two distinct regions: a sac-like structure containing the reproductive organs (the externa, and a trophic, root like system situated inside the hosts body (the interna. Parasitism results in the castration of their hosts, achieved by absorbing the entire reproductive energy of the host. Thus, the ratio of the host and parasite sizes is crucial for the understanding of the parasite's energetic cost. Using advanced imaging methods (micro-CT in conjunction with 3D modeling, we measured the volume of parasitic structures (externa, interna, egg mass, egg number, visceral mass and the volume of the entire host. Our results show positive correlations between the volume of (1 entire rhizocephalan (externa + interna and host body, (2 rhizocephalan externa and host body, (3 rhizocephalan visceral mass and rhizocephalan body, (4 egg mass and rhizocephalan externa, (5 rhizocephalan egg mass and their egg number. Comparing the rhizocephalan Sylon hippolytes, a parasite of caridean shrimps, and representatives of Peltogaster, parasites of hermit crabs, we could match their different traits on a reconstructed relationship. With this study we add new and significant information to our global understanding of the evolution of parasitic castrators, of interactions between a parasitic castrator and its host and of different parasitic strategies within parasitic castrators exemplified by rhizocephalans.

High-density hybrid interconnect methodologies

International Nuclear Information System (INIS)

John, J.; Zimmermann, L.; Moor, P.De; Hoof, C.Van

2003-01-01

Full text: The presentation gives an overview of the state-of-the-art of hybrid integration and in particular the IMEC technological approaches that will be able to address future hybrid detector needs. The dense hybrid flip-chip integration of an array of detectors and its dedicated readout electronics can be achieved with a variety of solderbump techniques such as pure Indium or Indium alloys, Ph-In, Ni/PbSn, but also conducting polymers... Particularly for cooled applications or ultra-high density applications, Indium solderbump technology (electroplated or evaporated) is the method of choice. The state-of-the-art of solderbump technologies that are to a high degree independent of the underlying detector material will be presented and examples of interconnect densities between 5x1E4cm-2 and 1x1E6 cm-2 will be demonstrated. For several classes of detectors, flip-chip integration is not allowed since the detectors have to be illuminated from the top. This applies to image sensors for EUV applications such as GaN/AlGaN based detectors and to MEMS-based sensors. In such cases, the only viable interconnection method has to be through the (thinned) detector wafer followed by a solderbump-based integration. The approaches for dense and ultra-dense through-the-wafer interconnect 'vias' will be presented and wafer thinning approaches will be shown

Anti-Ferroelectric Ceramics for High Energy Density Capacitors

Directory of Open Access Journals (Sweden)

Aditya Chauhan

2015-11-01

Full Text Available With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

Exploring high-density baryonic matter: Maximum freeze-out density

Energy Technology Data Exchange (ETDEWEB)

Randrup, Joergen [Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Cleymans, Jean [University of Cape Town, UCT-CERN Research Centre and Department of Physics, Rondebosch (South Africa)

2016-08-15

The hadronic freeze-out line is calculated in terms of the net baryon density and the energy density instead of the usual T and μ{sub B}. This analysis makes it apparent that the freeze-out density exhibits a maximum as the collision energy is varied. This maximum freeze-out density has μ{sub B} = 400 - 500 MeV, which is above the critical value, and it is reached for a fixed-target bombarding energy of 20-30 GeV/N well within the parameters of the proposed NICA collider facility. (orig.)

Low-enriched uranium high-density target project. Compendium report

Energy Technology Data Exchange (ETDEWEB)

Vandegrift, George; Brown, M. Alex; Jerden, James L.; Gelis, Artem V.; Stepinski, Dominique C.; Wiedmeyer, Stanley; Youker, Amanda; Hebden, Andrew; Solbrekken, G; Allen, C; Robertson., D; El-Gizawy, Sherif; Govindarajan, Srisharan; Hoyer, Annemarie; Makarewicz, Philip; Harris, Jacob; Graybill, Brian; Gunn, Andy; Berlin, James; Bryan, Chris; Sherman, Steven; Hobbs, Randy; Griffin, F. P.; Chandler, David; Hurt, C. J.; Williams, Paul; Creasy, John; Tjader, Barak; McFall, Danielle; Longmire, Hollie

2016-09-01

At present, most ⁹⁹Mo is produced in research, test, or isotope production reactors by irradiation of highly enriched uranium targets. To achieve the denser form of uranium needed for switching from high to low enriched uranium (LEU), targets in the form of a metal foil (~125-150 µm thick) are being developed. The LEU High Density Target Project successfully demonstrated several iterations of an LEU-fission-based Mo-99 technology that has the potential to provide the world’s supply of Mo-99, should major producers choose to utilize the technology. Over 50 annular high density targets have been successfully tested, and the assembly and disassembly of targets have been improved and optimized. Two target front-end processes (acidic and electrochemical) have been scaled up and demonstrated to allow for the high-density target technology to mate up to the existing producer technology for target processing. In the event that a new target processing line is started, the chemical processing of the targets is greatly simplified. Extensive modeling and safety analysis has been conducted, and the target has been qualified to be inserted into the High Flux Isotope Reactor, which is considered above and beyond the requirements for the typical use of this target due to high fluence and irradiation duration.

High Channel Count, High Density Microphone Arrays for Wind Tunnel Environments, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The Interdisciplinary Consulting Corporation (IC2) proposes the development of high channel count, high density, reduced cost per channel, directional microphone...

High current density magnets for INTOR and TIBER

International Nuclear Information System (INIS)

Miller, J.R.; Henning, C.D.; Kerns, J.A.; Slack, D.S.; Summers, L.T.; Zbasnik, J.P.

1986-12-01

The adoption of high current density, high field, superconducting magnets for INTOR and TIBER would prove beneficial. When combined with improved radiation tolerance of the magnets to minimize the inner leg shielding, a substantial reduction in machine dimensions and capital costs can be achieved. Fortunately, cable-in-conduit conductors (CICC) which are capable of the desired enhancements are being developed. Because conductor stability in a CICC depends more on the trapped helium enthalpy, rather than the copper resistivity, higher current densities of the order of 40 A/mm 2 at 12 T are possible. Radiation damage to the copper stabilizer is less important because the growth in resistance is a second-order effect on stability. Such CICC conductors lend themselves naturally to niobium-tin utilization, with the benefits of the high current-sharing temperature of this material being taken to advantage in absorbing radiation heating. When the helium coolant is injected at near the critical pressure, Joule-Thompson expansion in the flow path tends to stabilize the fluid temperature at under 6 K. Thus, higher fields, as well as higher current densities, can be considered for INTOR or TIBER

Surveys on Gyrodactylus parasites onwild Atlantic salmon in Denmark

DEFF Research Database (Denmark)

Jørgensen, Louise von Gersdorff; Heinecke, Rasmus Demuth; Buchmann, Kurt

Gyrodactylus salaris is a monogenean ectoparasite parasitizing salmonids in freshwater. This parasite is highly pathogenic to both Norwegian and Scottish salmon and has decimated the salmon populations in 45 Norwegian rivers after anthropogenic transfer from Sweden. G. salaris has also been found...... on several occasions in Danish rainbow trout farms but has never been recorded as a pathogenic parasite on Danish wild salmon. In the present study the occurrence of G. salaris and other Gyrodactylus parasites on wild Danish salmon fry and parr were monitored. Electrofishing was conducted in three river......-systems (River Skjern, Ribe and Varde) and 0+ and 1+ salmon were collected and sacrificed using an overdose of MS222. During spring or summer time more salmon fry and parr will be collected. The fins were excised and fins and body were conserved separately in 96% ethanol. In the laboratory, the fins and body...