359 research outputs found
A longitudinal empirical investigation of the pathways model of problem gambling
Background and Aims: The Pathways Model of Problem Gambling suggests the existence of
three developmental pathways to problem gambling, each differentiated by a set of predisposing
biopsychosocial characteristics: Behaviorally Conditioned (BC), Emotionally Vulnerable (EV),
and Biologically Vulnerable (BV) gamblers. This study examined the empirical validity of the
Pathways Model among adolescents followed up to early adulthood. Design: A prospectivelongitudinal design was used, thus overcoming limitations of past studies that used concurrent or
retrospective designs. Setting: Two samples were used: a) a population sample of French-speaking
adolescents (N = 1,033) living in low socio-economic status (SES) neighborhoods from the Greater
Region of Montreal (Quebec, Canada), and b) a population sample of adolescents (N = 3,017),
representative of French-speaking students in Quebec. Participants: Only participants with at-risk
or problem gambling by mid-adolescence or early adulthood were included in the main analysis
(n = 180). Analyses: Latent Profile Analyses were conducted to identify the optimal number of
profiles, in accordance with participantsâ scores on a set of variables prescribed by the Pathways
Model and measured during early adolescence: depression, anxiety, impulsivity, hyperactivity,
antisocial/aggressive behavior, and drug problems. Findings: A four-profile model fit the data
best. Three profiles differed from each other in ways consistent with the Pathways Model (i.e.,
BC, EV, and BV gamblers). A fourth profile emerged, resembling a combination of EV and BV
gamblers. Conclusions: Four profiles of at-risk and problem gamblers were identified. Three of
these profiles closely resemble those suggested by the Pathways Model
Young "Dipper" Stars in Upper Sco and Oph Observed by K2
We present ten young (10 Myr) late-K and M dwarf stars observed in
K2 Campaign 2 that host protoplanetary disks and exhibit quasi-periodic or
aperiodic dimming events. Their optical light curves show 10-20 dips in
flux over the 80-day observing campaign with durations of 0.5-2 days and
depths of up to 40%. These stars are all members of the Ophiuchus
(1 Myr) or Upper Scorpius (10 Myr) star-forming regions. To
investigate the nature of these "dippers" we obtained: optical and
near-infrared spectra to determine stellar properties and identify accretion
signatures; adaptive optics imaging to search for close companions that could
cause optical variations and/or influence disk evolution; and
millimeter-wavelength observations to constrain disk dust and gas masses. The
spectra reveal Li I absorption and H emission consistent with stellar
youth (<50 Myr), but also accretion rates spanning those of classical and
weak-line T Tauri stars. Infrared excesses are consistent with protoplanetary
disks extending to within 10 stellar radii in most cases; however, the
sub-mm observations imply disk masses that are an order of magnitude below
those of typical protoplanetary disks. We find a positive correlation between
dip depth and WISE-2 excess, which we interpret as evidence that the dipper
phenomenon is related to occulting structures in the inner disk, although this
is difficult to reconcile with the weakly accreting aperiodic dippers. We
consider three mechanisms to explain the dipper phenomenon: inner disk warps
near the co-rotation radius related to accretion; vortices at the inner disk
edge produced by the Rossby Wave Instability; and clumps of circumstellar
material related to planetesimal formation.Comment: Accepted to ApJ, 19 pages, 10 figure
X-ray structure of <i>Fasciola hepatica</i> Sigma class glutathione transferase 1 reveals a disulfide bond to support stability in gastro-intestinal environment
This is the final version. Available on open access from Nature Research via the DOI in this recordData delivery:
The structure factors and the refined coordinates of the FhGST-S1 structures have been deposited with the Protein Data Bank and have the access codes 2WB9 and 2WDU.Sigma class GST (Prostaglandin D synthase), FhGST-S1, is present in the excretoryâsecretory products (ES) of the liver fluke parasite Fasciola hepatica as cargo of extracellular vesicles (EVs) released by the parasite. FhGST-S1 has a well characterised role in the modulation of the immune response; a key fluke intercession that allows for establishment and development within their hosts. We have resolved the three-dimensional structure of FhGST-S1 in complex with its co-factor glutathione, in complex with a glutathione-cysteine adduct, and in a glutathione disulfide complex in order to initiate a research pipeline to mechanistically understand how FhGST-S1 functions within the host environment and to rationally design selective inhibitors. The overall fold of FhGST-S1 shows high structural similarity to other Sigma class GSTs. However, a unique interdomain disulfide bond was found in the FhGST-S1 which could stabilise the structure within the host gastro-intestinal environment. The position of the two domains of the protein with respect to each other is seen to be crucial in the formation of the active site cleft of the enzyme. The interdomain disulfide bond raises the possibility of oxidative regulation of the active site of this GST protein.European Union FP6Biotechnology and Biological Sciences Research Council (BBSRC)NRN WalesUniversity of Exete
In vitro biomarker discovery in the parasitic flatworm Fasciola hepatica for monitoring chemotherapeutic treatment
The parasitic flatworm Fasciola hepatica is a global food security risk. With no vaccines, the sustainability of triclabendazole (TCBZ) is threatened by emerging resistance. F. hepatica excretory/secretory (ES) products can be detected in host faeces and used to estimate TCBZ success and failure. However, there are no faecal based molecular diagnostics dedicated to assessing drug failure or resistance to TCBZ in the field. Utilising in vitro maintenance and sub-proteomic approaches two TCBZ stress ES protein response fingerprints were identified: markers of non-killing and lethal doses. This study provides candidate protein/peptide biomarkers to validate for detection of TCBZ failure and resistance
EPIC 220204960: A Quadruple Star System Containing Two Strongly Interacting Eclipsing Binaries
We present a strongly interacting quadruple system associated with the K2
target EPIC 220204960. The K2 target itself is a Kp = 12.7 magnitude star at
Teff ~ 6100 K which we designate as "B-N" (blue northerly image). The host of
the quadruple system, however, is a Kp = 17 magnitude star with a composite
M-star spectrum, which we designate as "R-S" (red southerly image). With a 3.2"
separation and similar radial velocities and photometric distances, 'B-N' is
likely physically associated with 'R-S', making this a quintuple system, but
that is incidental to our main claim of a strongly interacting quadruple system
in 'R-S'. The two binaries in 'R-S' have orbital periods of 13.27 d and 14.41
d, respectively, and each has an inclination angle of >89 degrees. From our
analysis of radial velocity measurements, and of the photometric lightcurve, we
conclude that all four stars are very similar with masses close to 0.4 Msun.
Both of the binaries exhibit significant ETVs where those of the primary and
secondary eclipses 'diverge' by 0.05 days over the course of the 80-day
observations. Via a systematic set of numerical simulations of quadruple
systems consisting of two interacting binaries, we conclude that the outer
orbital period is very likely to be between 300 and 500 days. If sufficient
time is devoted to RV studies of this faint target, the outer orbit should be
measurable within a year.Comment: 20 pages, 18 figures, 7 tables; accepted for publication in MNRA
Intestinal schistosomiasis in Uganda at high altitude (>1400 m): malacological and epidemiological surveys on Mount Elgon and in Fort Portal crater lakes reveal extra preventive chemotherapy needs
Background
Intestinal schistosomiasis is of public health importance in Uganda but communities living above 1400 m are not targeted for control as natural transmission is thought unlikely. To assess altitudinal boundaries and at-risk populations, conjoint malacological and epidemiological surveys were undertaken on Mount Elgon (1139 mâ3937 m), in Fort Portal crater lakes and in the Rwenzori Mountains (1123 mâ4050 m).
Methods
Seventy freshwater habitats [Mount Elgon (37), Fort Portal crater lakes (23), Rwenzori Mountains (8) and Lake Albert (2)] were inspected for Biomphalaria species. Water temperature, pH and conductivity were recorded. A parasitological examination of 756 schoolchildren [Mount Elgon (300), Fort Portal crater lakes (456)] by faecal microscopy of duplicate Kato-Katz smears from two consecutive stool samples was bolstered by antigen (urine-CCA dipstick) and antibody (SEA-ELISA) diagnostic assays.
Results
Biomphalaria spp. was found up to 1951 m on Mount Elgon and 1567 m in the Fort Portal crater lakes. Although no snail from Mount Elgon shed cercariae, molecular analysis judged 7.1% of snails sampled at altitudes above 1400 m as having DNA of Schistosoma mansoni; in Fort Portal crater lakes three snails shed schistosome cercariae. Prevalence of intestinal schistosomiasis as measured in schoolchildren by Kato-Katz (Mount Elgonâ=â5.3% v. Fort Portal crater lakesâ=â10.7%), CCA urine-dipsticks (18.3% v. 34.4%) and SEA-ELISA (42.3% v. 63.7%) showed negative associations with increasing altitude with some evidence of infection up to 2000 m.
Conclusions
Contrary to expectations, these surveys clearly show that natural transmission of intestinal schistosomiasis occurs above 1400 m, possibly extending up to 2000 m. Using spatial epidemiological predictions, this now places some extra six million people at-risk, denoting an expansion of preventive chemotherapy needs in Uganda
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