630 research outputs found
Leech (Annelida: Hirudinea) Infestations on Canadian Turtles, Including the First Canadian Record of Helobdella modesta from Freshwater Turtles
We collected leeches from freshwater turtles at two sites in southwestern Ontario. Five leech species (Placobdella parasitica, P. ornata, Helobdella modesta, Erpobdella punctata and Alboglossiphonia heteroclita) were collected from five turtle species (Chrysemys picta, Chelydra serpentina, Clemmys guttata, Emydoidea blandingii and Sternotherus odoratus). We report a new leech record (P. ornata) for C. guttata. The unexpectedly high frequency of H. modesta on freshwater turtles is discussed
Character Displacement in the Midst of Substantial Background Evolution in Anolis Lizard Island Populations
Negative interactions between species can generate divergent selection that causes character displacement. However, other processes cause similar divergence. We use spatial and temporal replication across island populations of Anolis lizards to assess the importance of negative interactions in driving trait shifts. Previous work showed that the establishment of Anolis sagrei on islands drove resident Anolis carolinensis to perch higher and evolve larger toepads. To further test the interaction\u27s causality and predictability, we resurveyed a subset of islands nine years later. Anolis sagrei had established on one island between surveys. We found that A. carolinensis on this island now perch higher and have larger toepads. However, toepad morphology change on this island was not distinct from shifts on six other islands whose Anolis community composition had not changed. Thus, the presence of A. sagrei only partly explains A. carolinensis trait variation across space and time. We also found that A. carolinensis on islands with previously established A. sagrei now perch higher than a decade ago, and that current A. carolinensis perch height is correlated with A. sagrei density. Our results suggest that character displacement likely interacts with other evolutionary processes in this system, and that temporal data are key to detecting such interactions
Thermodynamically admissible form for discrete hydrodynamics
We construct a discrete model of fluid particles according to the GENERIC
formalism. The model has the form of Smoothed Particle Hydrodynamics including
correct thermal fluctuations. A slight variation of the model reproduces the
Dissipative Particle Dynamics model with any desired thermodynamic behavior.
The resulting algorithm has the following properties: mass, momentum and energy
are conserved, entropy is a non-decreasing function of time and the thermal
fluctuations produce the correct Einstein distribution function at equilibrium.Comment: 4 page
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Cross-lagged relations between delayed actions and the wandering mind
The present study investigated the longitudinal relationship between procrastination and mind wandering. A total of 196 Chinese adults participated in the study across three time points, spaced four months apart. Findings based on a cross-lagged panel model suggested that procrastination predicted mind wandering over time, but not the vice versa, thereby indicating the unidimensionality of effects from procrastination to mind wandering. Procrastination may be attributed to self-regulatory failure, resulting in off-task activities such as mind wandering. However, mind wandering does not necessarily lead to dilatory behaviors. The present findings provide insight to practitioners regarding the predictive effects of procrastination on mind wandering
Macrophage migration inhibitory factor stimulated by Helicobacter pylori increases proliferation of gastric epithelial cells
AIM: Helicobacter pylori (H pylori) is associated with increased gastric inflammatory and epithelial expression of macrophage migration inhibitory factor (MIF) and gastric epithelial cell proliferation. This study aimed at determining whether H pylori directly stimulates release of MIF in monocytes, whether the cag pathogenicity island (PAI) is involved for this function, and whether MIF stimulated by H pylori increases gastric epithelial cell proliferation in vitro. METHODS: A cytotoxic wild-type H pylori strain (TN2)and its three isogenic mutants (TN2â–łcag, TN2â–łcagA and TN2â–łcagE) were co-cultured with cells of a human monocyte cell line, THP-1, for 24 h at different organism/cell ratios. MIF in the supernatants was measured by an ELISA. Cells of a human gastric cancer cell line, MKN45, were then co-cultured with the supernatants, with and without monoclonal anti-MIF antibody for 24 h. The cells were further incubated for 12 h after addition of (3)H-thymidine, and the levels of incorporation of (3)H-thymidine were measured with a liquid scintillation counter. RESULTS: The wild-type strain and the isogenic mutants, TN2â–łcagA and TN2â–łcagE, increased MIF release at organism/cell ratios of 200/1 and 400/1, but not at the ratios of 50/1 and 100/1. However, the mutant TN2â–łcag did not increase the release of MIF at any of the four ratios. (3)H-thymidine readings for MKN-45 cells were significantly increased with supernatants derived from the wild-type strain and the mutants TN2â–łcagA and TN2â–łcagE, but not from the mutant TN2â–łcag. Moreover, in the presence of monoclonal anti-MIF antibody, the stimulatory effects of the wild-type strain on cell proliferation disappeared. CONCLUSION: H pylori stimulates MIF release in monocytes, likely through its cag PAI, but not related to cagA or cagE. H pylori-stimulated monocyte culture supernatant increases gastric cell proliferation, which is blocked by anti-MIF antibody, suggesting that MIF plays an important role in H pylori-induced gastric epithelial cell proliferation
Evidence for partial melt in the crust beneath Mt. Paektu (Changbaishan), Democratic People's Republic of Korea and China
Mt. Paektu (also known as Changbaishan) is an enigmatic volcano on the border between the Democratic People's Republic of Korea (DPRK) and China. Despite being responsible for one of the largest eruptions in history, comparatively little is known about its magmatic evolution, geochronology, or underlying structure. We present receiver function results from an unprecedented seismic deployment in the DPRK. These are the first estimates of the crustal structure on the DPRK side of the volcano and, indeed, for anywhere beneath the DPRK. The crust 60 km from the volcano has a thickness of 35 km and a bulk / of 1.76, similar to that of the Sino-Korean craton. The / ratio increases ~20 km from the volcano, rising to >1.87 directly beneath the volcano. This shows that a large region of the crust has been modified by magmatism associated with the volcanism. Such high values of / suggest that partial melt is present in the crust beneath Mt. Paektu. This region of melt represents a potential source for magmas erupted in the last few thousand years and may be associated with an episode of volcanic unrest observed between 2002 and 2005.This work was supported by the Richard Lounsbery Foundation. The UK seismic instruments and data management facilities were provided under loan number 976 by SEIS-UK at the University of Leicester. The facilities of SEIS-UK are supported by the NERC under Agreement R8/H10/64. J.O.S.H. was supported by an NERC Fellowship NE/I020342/1
The future of enterprise groupware applications
This paper provides a review of groupware technology and products. The purpose of this review is to investigate the appropriateness of current groupware technology as the basis for future enterprise systems and evaluate its role in realising, the currently emerging, Virtual Enterprise model for business organisation. It also identifies in which way current technological phenomena will transform groupware technology and will drive the development of the enterprise systems of the future
Quantifying gas emissions from the "Millennium Eruption" of Paektu volcano, Democratic Peoples Republic of Korea/China
Paektu volcano (Changbaishan) is a rhyolitic caldera that straddles the border between the Democratic People’s Republic of Korea and China. Its most recent large eruption was the Millennium Eruption (ME; 23 km dense rock equivalent) circa 946 CE, which resulted in the release of copious magmatic volatiles (HO, CO, sulfur, and halogens). Accurate quantification of volatile yield and composition is critical in assessing volcanogenic climate impacts but is challenging, particularly for events before the satellite era. We use a geochemical technique to quantify volatile composition and upper bounds to yields for the ME by examining trends in incompatible trace and volatile element concentrations in crystal-hosted melt inclusions. We estimate that the ME could have emitted as much as 45 Tg of S to the atmosphere. This is greater than the quantity of S released by the 1815 eruption of Tambora, which contributed to the “year without a summer.” Our maximum gas yield estimates place the ME among the strongest emitters of climate-forcing gases in the Common Era. However, ice cores from Greenland record only a relatively weak sulfate signal attributed to the ME. We suggest that other factors came into play in minimizing the glaciochemical signature. This paradoxical case in which high S emissions do not result in a strong glacial sulfate signal may present a way forward in building more https://symplectic.admin.cam.ac.uk/objectedit.html?cid=1&oid=876954generalized models for interpreting which volcanic eruptions have produced large climate impacts.K.I. was supported by the NSF under award no. 1349486 and by AAAS. Fieldwork was supported by the Richard Lounsbery Foundation
An epidemiological study of pleuropulmonary paragonimiasis among pupils in the peri-urban zone of Kumba town, Meme Division, Cameroon
BACKGROUND: Paragonimiasis have previously been reported in two zones of the Southwest Province of Cameroon including the Kupe mountain and Mundani foci. The aim of this study was to investigate the presence and epidemiology of paragonimiasis in the peri-urban zone of Kumba, Meme Division, located about 50 km away from the Kupe mountain focus. METHODS: Pupils of several government primary schools in 5 villages around Kumba underwent both parasitologic and clinical investigations in search of signs and symptoms of paragonimiasis. Mycobacterium tuberculosis was also searched for in the differential diagnosis.Freshwater crabs from neighbouring streams in the five villages were dissected in search of paragonimus metacercariae. RESULTS: Out of a total of 1482 pupils examined in all five villages, 309 individuals (147 males and 162 females) were recruited for this study based on the presence of one or more signs or symptoms of paragonimiasis. Eggs of Paragonimus africanus were found in stools and/or sputum of pupils from all five villages, giving an overall paragonimus prevalence of 2.56%. There was no significant difference in the disease prevalence between the villages (X(2 )= 8.36, P = 0.08). The prevalence of Paragonimus africanus eggs amongst pupils with symptoms of paragonimiasis was 12.3% (38 of 309). Males were infected more than females (17.0% versus 8.0%), but the difference was not significant (X(2 )= 5.76, P = 0.16). All the 38 paragonimus egg positive subjects presented with cough, 23 (60.53%) complained of chest pain while 16 (42.11%) had haemoptysis. Stool examinations also detected some intestinal parasites including Ascaris lumbricoides (29.45%), Trichuris trichiura (6.47%), Necator americanus (2.27%), Strongyloides stercoralis (1.62%), Enterobius vermicularis (0.65%), and Entamoeba histolytica (4.53%). No case of M. tuberculosis was noted. Out of a total of 85 dissected crabs (Sudanonautes africanus), 6.02 % were infected with paragonimus metacercariae. CONCLUSION: In addition to the two previously described paragonimiasis foci of Kupe mountain and Mundani, the identification of autochthonous cases of paragonimiasis in the peri-urban zone of Kumba town, makes the South West Province the most endemic zone of paragonimiasis in Cameroon at present
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