6,336 research outputs found
Detection of high levels of congenital transmission of toxoplasma gondii in natural urban populations of mus domesticus
The relative importance of different transmission routes of Toxoplasma gondii has been a matter for debate. This ubiquitous parasite is generally thought to be transmitted by infective oocysts excreted by the definitive host, the cat. Ingestion of undercooked meat has also been considered an important route of transmission in many mammals while congenital transmission has generally been considered relatively rare. Experimental studies demonstrate the ability of T. gondii to be transmitted congenitally, but few studies have investigated the frequency of this transmission route in natural populations. We use PCR amplification of the SAG1 gene to investigate the frequency of congenital transmission in a wild population of mice (Mus domesticus) and show that congenital transmission is occurring in 75% of pregnancies in this population. Furthermore, for infected pregnant mice, transmission occurs to at least one foetus in 100% of cases while variable penetrance of congenital infection is observed. These high levels of congenital transmission in this wild population of mice, taken together with other recent data on congenital transmission in sheep, suggests that this phenomenon might be more widespread than previously thought
The prevalence of Neospora caninum and co-infection with Toxoplasma gondii by PCR analysis in naturally occurring mammal populations
Neospora caninum and Toxoplasma gondii are closely related intracellular protozoan parasites associated with bovine and ovine abortion respectively. Little is known about the extent of Neospora/Toxoplasma co-infection in naturally infected populations of animals. Using nested PCR techniques, based on primers from the Nc5 region of N. caninum and SAG1 for T. gondii, the prevalence of N. caninum and its co-infection with T. gondii were investigated in populations of Mus domesticus, Rattus norvegicus and aborted lambs (Ovis aries). A low frequency of infection with N. caninum was detected in the Mus domesticus (3%) and Rattus norvegicus (4·4%) populations. A relatively high frequency of infection with N. caninum was detected in the brains of aborted lambs (18·9%). There was no significant relationship between N. caninum and T. gondii co-infection. Investigation of the tissue distribution of Neospora, in aborted lambs, showed that Neospora could not be detected in tissues other than brain and this was in contrast to Toxoplasma where the parasite could be frequently detected in a range of tissues
The Thalamus and Brainstem Act As Key Hubs in Alterations of Human Brain Network Connectivity Induced by Mild Propofol Sedation
Despite their routine use during surgical procedures, no consensus has yet been reached on the precise mechanisms by which hypnotic anesthetic agents produce their effects. Molecular, animal and human studies have suggested disruption of thalamocortical communication as a key component of anesthetic action at the brain systems level. Here, we used the anesthetic agent, propofol, to modulate consciousness and to evaluate differences in the interactions of remote neural networks during altered consciousness. We investigated the effects of propofol, at a dose that produced mild sedation without loss of consciousness, on spontaneous cerebral activity of 15 healthy volunteers using functional magnetic resonance imaging (fMRI), exploiting oscillations (<0.1 Hz) in blood oxygenation level-dependent signal across functionally connected brain regions. We considered the data as a graph, or complex network of nodes and links, and used eigenvector centrality (EC) to characterize brain network properties. The EC mapping of fMRI data in healthy humans under propofol mild sedation demonstrated a decrease of centrality of the thalamus versus an increase of centrality within the pons of the brainstem, highlighting the important role of these two structures in regulating consciousness. Specifically, the decrease of thalamus centrality results from its disconnection from a widespread set of cortical and subcortical regions, while the increase of brainstem centrality may be a consequence of its increased influence, in the mildly sedated state, over a few highly central cortical regions key to the default mode network such as the posterior and anterior cingulate cortices
Soundscape reproduction and synthesis
The aims of this work were to investigate (i) whether soundscape perceptual dimensions are correctly reproduced by ambisonic loudspeaker playback, (ii) whether soundscape dimensional analysis is robust to changes of location and from the field to laboratory playback, and (iii) whether a simple soundscape synthesis can be used to interactively design a soundscape. The first two aims were addressed by an experiment which attempted to repeat the dimensional analysis made by Kang (Kang, J. (2007), Urban Sound Environment.
London: Taylor and Francis). Kang used semantic differential scales to conduct an in-situ survey of two urban soundscapes in Sheffield, UK. He used factor analysis to derive four perceptual dimensions from the responses. The present work repeated this approach, but the fifteen participants were judging ambisonic recordings of four soundscapes in Manchester, UK. The present work found very similar dimensions to Kang but with more variance explained: relaxation/calmness (41%), dynamics/vibrancy (10%), communication (7%) and
spatiality (7%). The dimensions from the two studies load onto the semantic scales in a similar way. These results indicate that an ambisonic reproduction of a soundscape gives similar results to field experiments, though with more variance explained. They also show that dimensional analysis of soundscape response is robust enough to produce similar results for different locations in different cities.
To investigate the third aim, the ambisonic reproduction was extended to a system which allowed independent interactive control of sixteen foreground sounds set in an ambisonic background soundscape. Eight participants were able to use this system to successfully design a soundscape that expressed their intentions. It was found that the designed soundscapes seemed to be based more on participant expectation of typical urban soundscapes than on their preference for individual sounds. These results suggest that a more sophisticated soundscape synthesiser might be suitable for real design problems
Isolated aortic root dilation in homocystinuria
BACKGROUND: Vascular complications in homocystinuria have been known for many years, but there have been no reports to date on involvement of the ascending aorta. METHODS: We conducted a cross-sectional study of patients with homocystinuria, known to a single metabolic centre, and evaluated in 2016 with a transthoracic echocardiogram. Aortic root dilation was defined as Z-score ≥ 2.0 SD, and graded mild (Z-score 2.0-3.0), moderate (Z-score 3.01-4.0) and severe (Z-score > 4.0). RESULTS: The study population included 34 patients, median age of 44.3 years (IQR 33.3-52.2), 50% males, 69% diagnosed aged <18 years and 29% pyridoxine-responsive. Eight (24%) had a history of hypertension. Seven patients (21%) were found to have a dilation of the aortic root, mild in two cases (6%), moderate in four (12%) and severe in one (3%). None had dilation of the ascending aorta. Significant aortic regurgitation, secondary to moderate aortic root dilation, was documented in two patients. A single patient had significant mitral regurgitation due to prolapse of both valve leaflets, as well as mild aortic root dilation. Comparing patients with a dilation of the aortic root to those without, there were no significant clinical, laboratory or echocardiographic differences, with the only exception being that the diameter of the ascending aorta was larger in the group with a dilated aortic root, albeit within normal limits. CONCLUSIONS: A subset of patients with homocystinuria have isolated dilation of the aortic root similar to that observed in Marfan syndrome
Boundaries of Semantic Distraction: Dominance and Lexicality Act at Retrieval
Three experiments investigated memory for semantic information with the goal of determining boundary conditions for the manifestation of semantic auditory distraction. Irrelevant speech disrupted the free recall of semantic category-exemplars to an equal degree regardless of whether the speech coincided with presentation or test phases of the task (Experiment 1) and occurred regardless of whether it comprised random words or coherent sentences (Experiment 2). The effects of background speech were greater when the irrelevant speech was semantically related to the to-be-remembered material, but only when the irrelevant words were high in output dominance (Experiment 3). The implications of these findings in relation to the processing of task material and the processing of background speech is discussed
Ultraluminous Infrared Galaxies
At luminosities above ~10^{11} L_sun, infrared galaxies become the dominant
population of extragalactic objects in the local Universe (z < 0.5), being more
numerous than optically selected starburst and Seyfert galaxies, and QSOs at
comparable bolometric luminosity. At the highest luminosities, ultraluminous
infrared galaxies (ULIGs: L_ir > 10^{12} L_sun), outnumber optically selected
QSOs by a factor of ~1.5-2. All of the nearest ULIGs (z < 0.1) appear to be
advanced mergers that are powered by both a circumnuclear starburst and AGN,
both of which are fueled by an enormous concentration of molecular gas
(~10^{10} M_sun) that has been funneled into the merger nucleus. ULIGs may
represent a primary stage in the formation of massive black holes and
elliptical galaxy cores. The intense circumnuclear starburst that accompanies
the ULIG phase may also represent a primary stage in the formation of globular
clusters, and the metal enrichment of the intergalactic medium by gas and dust
expelled from the nucleus due to the combined forces of supernova explosions
and powerful stellar winds.Comment: LaTex, 6 pages with 4 embedded .eps figures. Postscript version plus
color plates available at
http://www.ifa.hawaii.edu/users/sanders/astroph/s186/plates.html To appear in
"Galaxy Interactions at Low and High Redshift" IAU Symposium 186, Kyoto,
Japan, eds. J.E. Barnes and D.B. Sander
An Intelligent Safety System for Human-Centered Semi-Autonomous Vehicles
Nowadays, automobile manufacturers make efforts to develop ways to make cars
fully safe. Monitoring driver's actions by computer vision techniques to detect
driving mistakes in real-time and then planning for autonomous driving to avoid
vehicle collisions is one of the most important issues that has been
investigated in the machine vision and Intelligent Transportation Systems
(ITS). The main goal of this study is to prevent accidents caused by fatigue,
drowsiness, and driver distraction. To avoid these incidents, this paper
proposes an integrated safety system that continuously monitors the driver's
attention and vehicle surroundings, and finally decides whether the actual
steering control status is safe or not. For this purpose, we equipped an
ordinary car called FARAZ with a vision system consisting of four mounted
cameras along with a universal car tool for communicating with surrounding
factory-installed sensors and other car systems, and sending commands to
actuators. The proposed system leverages a scene understanding pipeline using
deep convolutional encoder-decoder networks and a driver state detection
pipeline. We have been identifying and assessing domestic capabilities for the
development of technologies specifically of the ordinary vehicles in order to
manufacture smart cars and eke providing an intelligent system to increase
safety and to assist the driver in various conditions/situations.Comment: 15 pages and 5 figures, Submitted to the international conference on
Contemporary issues in Data Science (CiDaS 2019), Learn more about this
project at https://iasbs.ac.ir/~ansari/fara
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