Parasites in space and time: a novel method to assess and illustrate host-searching behaviour of trematode cercariae

Parasitology ◽  
2018 ◽  
Vol 145 (11) ◽  
pp. 1469-1474 ◽  
Author(s):  
Christian Selbach ◽  
Robert Poulin
Keyword(s):  
Life Histories ◽  
Parasite Community ◽  
Video Tracking ◽  
Trematode Species ◽  
Host Searching ◽  
Novel Method ◽  
The Individual ◽  
Individual Strategies ◽  
Host Parasite ◽  
Automated Video Tracking

AbstractThe transmission from one host to another constitutes a challenging obstacle for parasites and is a key determinant of their fitness. Due to their complex life histories involving several different hosts, the free-living dispersal stages (cercariae) of digenean trematodes show a huge diversity in morphology and behaviour. On a finer scale, we still have an extremely limited understanding of the inter- and intraspecific variation in transmission strategies of many trematode species. Here, we present a novel method to study the movement patterns of cercariae of four New Zealand trematode species (Coitocaecum parvum, Maritrema poulini, Apatemon sp. and Aporocotylid sp. I.) via automated video tracking. This approach allows to quantify parameters otherwise not measurable and clearly illustrates the individual strategies of parasites to search for their respective target hosts. Cercariae that seek out an evasive fish target hosts showed higher swimming speeds (acceleration and velocity) and travelled further distances, compared with species searching for high-density crustacean hosts. Automated video tracking provides a powerful tool for such detailed analyses of parasites’ host-searching strategies and can enhance our understanding of complex host–parasite interactions, ranging from parasite community structure to the transmission of potential disease agents.

scholarly journals Anisotropic interaction and motion states of locusts in a hopper band

2021 ◽  
Author(s):  
Jasper Weinburd ◽  
Jacob Landsberg ◽  
Anna Kravtsova ◽  
Shanni Lam ◽  
Tarush Sharma ◽  
...  
Keyword(s):  
Collective Motion ◽  
Video Tracking ◽  
Low Density ◽  
Natural Setting ◽  
Trajectory Data ◽  
Novel Interactions ◽  
The Individual ◽  
Low Density Area ◽  
Australian Plague Locust ◽  
Automated Video Tracking

Swarming locusts present a quintessential example of animal collective motion. Juvenile locusts march and hop across the ground in coordinated groups called hopper bands. Composed of up to millions of insects, hopper bands exhibit coordinated motion and various collective structures. These groups are well-documented in the field, but the individual insects themselves are typically studied in much smaller groups in laboratory experiments. We present the first trajectory data that detail the movement of individual locusts within a hopper band in a natural setting. Using automated video tracking, we derive our data from footage of four distinct hopper bands of the Australian plague locust, Chortoicetes terminifera. We reconstruct nearly twenty-thousand individual trajectories composed of over 3.3 million locust positions. We classify these data into three motion states: stationary, walking, and hopping. Distributions of relative neighbor positions reveal anisotropies that depend on motion state. Stationary locusts have high-density areas distributed around them apparently at random. Walking locusts have a low-density area in front of them. Hopping locusts have low-density areas in front and behind them. Our results suggest novel interactions, namely that locusts change their motion to avoid colliding with neighbors in front of them.

Polycrystalline Silicon Gettering Layers with Controlled Residual Stress

2013 ◽  
Vol 205-206 ◽  
pp. 284-289 ◽  
Author(s):  
David Lysáček ◽  
Petr Kostelník ◽  
Petr Pánek
Keyword(s):  
Residual Stress ◽  
Vapor Deposition ◽  
Polycrystalline Silicon ◽  
Opposite Sign ◽  
Chemical Vapor ◽  
Pressure Chemical ◽  
Novel Method ◽  
The Individual ◽  
Scanning Electron

We report on a novel method of low pressure chemical vapor deposition of polycrystalline silicon layers used for external gettering in silicon substrate for semiconductor applications. The proposed method allowed us to produce layers of polycrystalline silicon with pre-determined residual stress. The method is based on the deposition of a multilayer system formed by two layers. The first layer is intentionally designed to have tensile stress while the second layer has compressive stress. Opposite sign of the residual stresses of the individual layers enables to pre-determine the residual stress of the gettering stack. We used scanning electron microscopy for structural characterization of the layers and intentional contamination for demonstration of the gettering properties. Residual stress of the layers was calculated from the wafer curvature.

Consistent differences in macroparasite community composition among populations of three-spined sticklebacks,Gasterosteus aculeatusL.

Parasitology ◽  
2012 ◽  
Vol 139 (11) ◽  
pp. 1478-1491 ◽  
Author(s):  
JOB DE ROIJ ◽  
ANDREW D. C. MacCOLL
Keyword(s):  
Spatial Variation ◽  
Community Composition ◽  
Gasterosteus Aculeatus ◽  
Parasite Community ◽  
Field Studies ◽  
Habitat Characteristics ◽  
Parasite Communities ◽  
Geographical Distances ◽  
Host Parasite ◽  
Relative Differences

SUMMARYParasite ecologists are often interested in the repeatability of patterns in parasite communities in space and/or time, because of implications for the dynamics of host-parasite interactions. Field studies usually examine temporal and spatial variation in isolation or limit themselves to a small number of host populations. Here, we studied the macroparasite communities of 12 populations of three-spined stickleback,Gasterosteus aculeatusL., on North Uist, Scotland, separated by small geographical distances, during the breeding season in 2 consecutive years (2007 and 2008) to determine: (1) the extent of spatial variation in macroparasite communities, (2) whether this variation is consistent across years, and (3) whether habitat characteristics can explain differences in macroparasite community composition among populations. We found substantial variation in parasite communities among populations. Generally, measures of parasite community composition were higher in 2008 than in 2007, but this effect of year was consistent across populations, such that the relative differences in these measures among populations changed little between years. These data suggest that there is short-term stability in the spatial variation in macroparasite communities of North Uist sticklebacks. However, none of the 5 habitat characteristics measured explained spatial variation in any measure of parasite community composition.

scholarly journals Avian Haemosporidian Diversity on Sardinia: A First General Assessment for the Insular Mediterranean

Diversity ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 75
Author(s):  
Irene Pellegrino ◽  
Luca Ilahiane ◽  
Giovanni Boano ◽  
Marco Cucco ◽  
Marco Pavia ◽  
...  
Keyword(s):  
Linear Models ◽  
Parasite Community ◽  
Breeding Birds ◽  
Lower Probability ◽  
Long Distance ◽  
Breeding Bird ◽  
Bird Populations ◽  
Total Prevalence ◽  
Western Palearctic ◽  
Host Parasite

The Western Palearctic is one of the most investigated regions for avian haemosporidian parasites (Haemoproteus, Plasmodium and Leucocytozoon), yet geographic gaps in our regional knowledge remain. Here, we report the first haemosporidian screening of the breeding birds from Sardinia (the second-largest Mediterranean Island and a biodiversity hotspot), and the first for the insular Mediterranean in general. We examined the occurrence of haemosporidians by amplifying their mtDNA cytb gene in 217 breeding birds, belonging to 32 species. The total prevalence of infected birds was 55.3%, and of the 116 haplotypes recovered, 84 were novel. Despite the high number of novel lineages, phylogenetic analysis did not highlight Sardinia-specific clades; instead, some Sardinian lineages were more closely related to lineages previously recovered from continental Europe. Host-parasite network analysis indicated a specialized host-parasite community. Binomial generalized linear models (GLMs), performed at the community level, suggested an elevational effect on haemosporidian occurrence probability (negative for Haemoproteus; positive for Leucocytozoon) likely due to differences in the abundance of insect vectors at different elevations. Furthermore, a GLM revealed that sedentary birds showed a higher probability of being infected by novel haplotypes and long-distance migrants showed a lower probability of novel haplotype infection. We hypothesize that the high diversity of haemosporidians is linked to the isolation of breeding bird populations on Sardinia. This study adds to the growing knowledge on haemosporidians lineage diversity and distribution in insular environments and presents new insights on potential host-parasite associations.

Perceived Causal Problem Networks: Reliability, Central Problems, and Clinical Utility for Depression

Assessment ◽  
2021 ◽  
pp. 107319112110392
Author(s):  
Lars Klintwall ◽  
Martin Bellander ◽  
Matti Cervin
Keyword(s):  
Clinical Utility ◽  
Treatment Success ◽  
Centrality Measures ◽  
Retest Reliability ◽  
Causal Relations ◽  
Future Studies ◽  
Causal Networks ◽  
Novel Method ◽  
The Individual ◽  
Test Retest Reliability

Personalized case conceptualization is often regarded as a prerequisite for treatment success in psychotherapy for patients with comorbidity. This article presents Perceived Causal Networks, a novel method in which patients rate perceived causal relations among behavioral and emotional problems. First, 231 respondents screening positive for depression completed an online Perceived Causal Networks questionnaire. Median completion time (including repeat items to assess immediate test–retest reliability) was 22.7 minutes, and centrality measures showed excellent immediate test–retest reliability. Networks were highly idiosyncratic, but worrying and ruminating were the most central items for a third of respondents. Second, 50 psychotherapists rated the clinical utility of Perceived Causal Networks visualizations. Ninety-six percent rated the networks as clinically useful, and the information in the individual visualizations was judged to contain 47% of the information typically collected during a psychotherapy assessment phase. Future studies should individualize networks further and evaluate the validity of perceived causal relations.

scholarly journals Will You Come Back to Contribute? Investigating the Inactivity of OSS Core Developers in GitHub

2021 ◽  
Author(s):  
Fabio Calefato ◽  
Marco Aurelio Gerosa ◽  
Giuseppe Iaffaldano ◽  
Filippo Lanubile ◽  
Igor Fabio Steinmacher
Keyword(s):  
Open Source ◽  
Open Source Software ◽  
State Transition ◽  
Active State ◽  
State Model ◽  
Novel Method ◽  
To Come ◽  
One Year ◽  
The Individual ◽  
To Receive

Abstract Several Open-Source Software (OSS) projects depend on the continuity of their development communities to remain sustainable. Understanding how developers become inactive or why they take breaks can help communities prevent abandonment and incentivize developers to come back. In this paper, we propose a novel method to identify developers’ inactive periods by analyzing the individual rhythm of contributions to the projects. Using this method, we quantitatively analyze the inactivity of core developers in 18 OSS organizations hosted on GitHub. We also survey core developers to receive their feedback about the identified breaks and transitions. Our results show that our method was effective for identifying developers’ breaks. About 94% of the surveyed core developers agreed with our state model of inactivity; 71% and 79% of them acknowledged their breaks and state transition, respectively. We also show that all core developers take breaks (at least once) and about a half of them (~ 45%) have completely disengaged from a project for at least one year. We also analyzed the probability of transitions to/from inactivity and found that developers who pause their activity have a ~ 35 to ~ 55% chance to return to an active state; yet, if the break lasts for a year or longer, then the probability of resuming activities drops to ~ 21–26%, with a ~ 54% chance of complete disengagement. These results may support the creation of policies and mechanisms to make OSS community managers aware of breaks and potential project abandonment.

scholarly journals "When you marry a Serb, then you do not have any problems". Foreigners in Serbia - introduction to anthropological analysis

Stanovnistvo ◽  
2016 ◽  
Vol 54 (2) ◽  
pp. 105-125
Author(s):  
Marija Brujic
Keyword(s):  
Life Histories ◽  
Highly Qualified ◽  
Integration Policy ◽  
Integration Process ◽  
Structured Interviews ◽  
German Woman ◽  
Irregular Migrants ◽  
Eu Integration ◽  
Individual Strategies ◽  
The Eu

Although according to some scholars, Serbia does not have great immigration potential, there is more and more research within social science?s framework about immigrants in Serbia. However, the majority of these papers focus on current ?migration crisis? and, in relation to this, asylum seekers and irregular migrants. Therefore, this paper has had manifold aims. Firstly, the paper has drawn attention to the anthropological study of foreigners who live and work in Serbia. Secondly, it has revealed some of the problems they had been confronted with in reality. Within this framework, the focus was on highly qualified female foreigners from the EU countries who came for love or/and work which is a topic that does not occupy a prominent place in anthropological research in Serbia. However, with regard to the EU-integration of Serbia and Europeanization of migratory policies, the research of personal experiences of foreigners living in Serbia could signify the gaps in migrants? integration policy and in the adaptation of migration strategies. Thus, in this research were used in-depth semi-structured interviews conducted in 2016 in Belgrade as a method of collecting data and the ?bottom-up? approach. As a result, in this paper were analyzed narratives of a German and a British woman about their everyday experiences connected with their residing and working status. Their narratives showed their struggle with Serbian bureaucracy and related to this, how they legalized their ?migratory status?. Furthermore, in the analysis of the micro context the term ?ethnography of particular? was used, an approach developed by Lila Abu-Lughod in order to, one the one hand, avoid generalization and, on the other, to focus on individual life histories, which is an approach usually used in socio-anthropological studies. In particular, the paper stresses the relevance of individual strategies used for regulation of residence of foreigners in Serbia. Both British and German woman are married to Serbs, have no children, speak The Serbian language, socialize mainly with the Serbs and live and work in Belgrade. While German woman came during Milosevic?s regime in 1999, the British woman came in 2002. Although they did not suffer from ?professional deskilling?, which is typical for female migration in general, they both had to prequalify in order to find a job in Serbia. However, they both found it was easier to regulate their residence status through family, not working, visa, especially before new legal documents concerning foreigners? status were introduced. For instance, the most important legal document adopted as part of EU-integration process are Law on Foreigners (2008), Law on Migration Management (2012) and Law on Employment and Work of Foreign Citizens (2014). Foreigners living in Serbia represent the important group as many of them either work or use their pensions in Serbia. Therefore, having in mind the importance of Europeanization of migratory strategies in Serbia within Europeanization of Serbia and EU-integration process in general and possible migration of EU nationals to Serbia, this paper discussed the importance of individual (working) migration to Serbia on a micro level.

Host–Parasite Relationships and Life Histories of Trypanosomes in Australia

2017 ◽  
pp. 47-109 ◽  
Author(s):  
C. Cooper ◽  
P.L. Clode ◽  
C. Peacock ◽  
R.C.A. Thompson
Keyword(s):  
Life Histories ◽  
Host Parasite

Ethology: The Narrative Turn

2021 ◽  
Author(s):  
Dominique Lestel
Keyword(s):  
Field Data ◽  
Homo Sapiens ◽  
Cognitive Ethology ◽  
Philosophical Question ◽  
Animal Intelligence ◽  
Narrative Structures ◽  
Methodological Tool ◽  
Third Person ◽  
The Individual ◽  
Individual Strategies

Distinguishing their work from the causalist approaches of objectivist ethology, sociobiology, or cognitive ethology, a growing number of ethologists lay claim to the possibility of describing what animals do through more or less complex narratives. Narration becomes a methodological tool in its own right. Animals thus become characters as in novels. This is an epistemological choice. Our capacity to perceive the complexity of animal lives is tied to our capacity to tell ourselves stories in which animals are the heroes. These animals are not robots. They are subjects, individuals, and even persons. From this results a new and transpecific form of third-person narration. This approach still relies, however, on a set of very carefully collected field data and requires a great familiarity with observed animals. It then becomes possible to concern oneself with the individual strategies of particular animals rather than solely with behaviors that would be common to all members of a given species. The recourse to narrative as a means of understanding animal intelligence is especially pertinent as we become increasingly aware that animals themselves tell stories and that our concepts of narrative must expand beyond the human. Knowing whether animals have narrative structures is a philosophical question before it is a biological one. The desire to extend narrativity to the animal necessarily modifies what narrativity signifies. We perceive in animals a processual narrativity, a behavioral narrativity, and a fictional narrativity. The study of animals forces to rethink what a fiction is and compels one to consider its phylogensis in a rigorous manner without locating its origins in Homo sapiens.

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