1,325 research outputs found

    Pulsars Cannot Account for the Inner Galaxy's GeV Excess

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    Using data from the Fermi Gamma-Ray Space Telescope, a spatially extended component of gamma rays has been identified from the direction of the Galactic Center, peaking at energies of ~2-3 GeV. More recently, it has been shown that this signal is not confined to the innermost hundreds of parsecs of the Galaxy, but instead extends to at least ~3 kpc from the Galactic Center. While the spectrum, intensity, and angular distribution of this signal is in good agreement with predictions from annihilating dark matter, it has also been suggested that a population of unresolved millisecond pulsars could be responsible for this excess GeV emission from the Inner Galaxy. In this paper, we consider this later possibility in detail. Comparing the observed spectral shape of the Inner Galaxy's GeV excess to the spectrum measured from 37 millisecond pulsars by Fermi, we find that these sources exhibit a spectral shape that is much too soft at sub-GeV energies to accommodate this signal. We also construct population models to describe the spatial distribution and luminosity function of the Milky Way's millisecond pulsars. After taking into account constraints from the observed distribution of Fermi sources (including both sources known to be millisecond pulsars, and unidentified sources which could be pulsars), we find that millisecond pulsars can account for no more than ~10% of the Inner Galaxy's GeV excess. Each of these arguments strongly disfavor millisecond pulsars as the source of this signal.Comment: 13 pages, 11 figure

    An evaluation of infant visual acuity using Lea Grating paddles and Teller Acuity Cards

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    Purpose: Basic research to determine clinical validity of the Lea Grating paddles has not yet been conducted. 10 This study involves the evaluation of infant (0 to 18 months) grating acuity with Lea Grating Paddles and Teller Acuity Cards (TAC) in a clinical setting. The goal is to compare the acuity measure obtained with both methods, and establish age-related acuity norms for the newer Lea Grating system. Methods: Thirty-frve subjects were recruited with parent/guardian consent. Subjects were comprised of newborns and infants ranging in age from 5 days to I 7 months. The assessment of infant visual acuity was performed using the Lea Grating Paddles and the Teller Acuity Cards. Procedural manuals for both techniques were used as reference guidelines. Testing was performed in a standard examination room with normal room illumination. One tester presented the gratings to the infant and determined which direction the infant was looking, while another tester documented acuity levels based on the first tester\u27s observations. Binocular testing followed by monocular testing was conducted. Testing took approximately 15 minutes to complete per child. Results: T-testing showed no significant difference between the Lea Paddles and TAC binocular means for each four-month interval age group. ANOVA binocular testing for the Lea Paddles and TAC indicated an asymptotic increase in acuity with age, leveling-off starting at four months and older. ANOVA monocular results for both procedures suggested a sigmoidal increase in acuity with age, leveling-off between 4- I 2 months of age. According to the scatter plot, a strong correlation was found for both procedures when means were calculated for the four interval age groups. Correlation coefficient between the Lea Paddles and TAC for binocular and monocular findings were 0.9930 and 0.9910 respectively. Conclusion: In summary, it was found that any benefit of the Lea Grating Paddles over the TAC is primarily for the clinician. It was easier to obtain the attention of the infants with the Lea Grating Paddles. In addition, the lower cost and increased portability of the Lea Grating Paddles are desirable features for the clinician. While values in this study corresponded with the norms set by the Lea manual, future studies may be useful to establish a larger base of normative data

    Neurophysiology in psychosis: The quest for disease biomarkers

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    Psychotic disorders affect 3% of the population at some stage in life, are a leading cause of disability, and impose a great economic burden on society. Major breakthroughs in the genetics of psychosis have not yet been matched by an understanding of its neurobiology. Biomarkers of perception and cognition obtained through non-invasive neurophysiological tools, especially EEG, offer a unique opportunity to gain mechanistic insights. Techniques for measuring neurophysiological markers are inexpensive and ubiquitous, thus having the potential as an accessible tool for patient stratification towards early treatments leading to better outcomes. In this paper, we review the literature on neurophysiological markers for psychosis and their relevant disease mechanisms, mainly covering event-related potentials including P50/N100 sensory gating, mismatch negativity, and the N100 and P300 waveforms. While several neurophysiological deficits are well established in patients with psychosis, more research is needed to study neurophysiological markers in their unaffected relatives and individuals at clinical high risk. We need to harness EEG to investigate markers of disease risk as key steps to elucidate the aetiology of psychosis and facilitate earlier detection and treatment

    Clostridium perfringens epsilon toxin induces blood brain barrier permeability via caveolae-dependent transcytosis and requires expression of MAL.

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    Clostridium perfringens epsilon toxin (ETX) is responsible for causing the economically devastating disease, enterotoxaemia, in livestock. It is well accepted that ETX causes blood brain barrier (BBB) permeability, however the mechanisms involved in this process are not well understood. Using in vivo and in vitro methods, we determined that ETX causes BBB permeability in mice by increasing caveolae-dependent transcytosis in brain endothelial cells. When mice are intravenously injected with ETX, robust ETX binding is observed in the microvasculature of the central nervous system (CNS) with limited to no binding observed in the vasculature of peripheral organs, indicating that ETX specifically targets CNS endothelial cells. ETX binding to CNS microvasculature is dependent on MAL expression, as ETX binding to CNS microvasculature of MAL-deficient mice was not detected. ETX treatment also induces extravasation of molecular tracers including 376Da fluorescein salt, 60kDA serum albumin, 70kDa dextran, and 155kDA IgG. Importantly, ETX-induced BBB permeability requires expression of both MAL and caveolin-1, as mice deficient in MAL or caveolin-1 did not exhibit ETX-induced BBB permeability. Examination of primary murine brain endothelial cells revealed an increase in caveolae in ETX-treated cells, resulting in dynamin and lipid raft-dependent vacuolation without cell death. ETX-treatment also results in a rapid loss of EEA1 positive early endosomes and accumulation of large, RAB7-positive late endosomes and multivesicular bodies. Based on these results, we hypothesize that ETX binds to MAL on the apical surface of brain endothelial cells, causing recruitment of caveolin-1, triggering caveolae formation and internalization. Internalized caveolae fuse with early endosomes which traffic to late endosomes and multivesicular bodies. We believe that these multivesicular bodies fuse basally, releasing their contents into the brain parenchyma

    Relations between a computerized shopping task and cognitive tests in a group of persons diagnosed with schizophrenia compared with healthy controls

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    Cognitive deficits are clearly associated with poor everyday life functioning in persons diagnosed with schizophrenia. However, previous studies have primarily used questionnaires to assess everyday life functioning. We developed a computerized real-life activity task (shopping task), where participants are required to shop for a list of seven grocery store items. Thirty individuals diagnosed with schizophrenia and 30 healthy controls were administered an extensive battery of cognitive tests and the computerized shopping task. Performances on the computerized shopping task significantly differentiated patients and healthy controls for several variables. Moreover, performance on the shopping task was significantly correlated with verbal episodic memory, cognitive flexibility, planning, processing speed, and inhibition. Finally, performance on the computerized shopping task was significantly correlated with various clinical variables and with a global measure of social functioning. These findings suggest that the computerized task used in the present study provides an indication of the level of everyday life functioning and cognitive functioning of persons diagnosed with schizophrenia, and, therefore, may be viewed as a valuable instrument in both an evaluation and remediation context. (JINS, 2010, 16, 180-189.

    Antibody responses to a Cryptosporidium parvum rCP15/60 vaccine

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    Cryptosporidium parvum is a zoonotic apicomplexa-protozoan pathogen that causes gastroenteritis and diarrhoea in mammals worldwide. The organism is transmitted by ingestion of oocysts, which are shed in faeces, and completes its lifecycle in a single host.^1^ C. parvum is ubiquitous on dairy operations worldwide and is one of the leading causes of diarrhoea in calves on these farms.^2,3^ Here, for the first time, we describe the antibody response in a large group of cows to a recombinant C. parvum oocyst surface protein (rCP15/60) vaccine and the antibody response in calves fed rCP15/60-immune colostrum produced by these vaccinated cows. Results of recent genotype surveys indicate that calves are the only major reservoir for C. parvum infections in humans.^4^ Human C. parvum infections are particularly prevalent and often fatal in neonates in developing countries and to immunocompromised people, such as AIDs patients.^4^ Drug therapy against cryptosporidiosis is limited and not wholly efficacious in either humans or calves^5^, making development of an effective vaccine of paramount importance. To date, there is no commercially available effective vaccine against C. parvum, although passive immunization utilizing different zoite surface (glyco)proteins has showed promise.^6-9^ All cows we vaccinated produced an antibody response to the rCP15/60 vaccine and the magnitude of response correlated strongly with the subsequent level of antibody in their colostrum. All calves fed rCP15/60-immune colostrum showed a dose-dependent absorption of antibody. Our results demonstrate that vaccination of cows with rCP15/60 successfully induces antibodies against CP15/60 in their serum and colostrum and that these antibodies are then well absorbed when fed to neonatal calves. With further research, this C. parvum vaccine may well be a practical method of conferring passive protection to calves against cryptosporidiosis. Furthermore, a specifically targeted immune-colostrum may be valuable in protection and treatment of immunocompromised human patients with cryptosporidiosis

    Extended and cumulative effects of experimentally induced intergroup conflict in a cooperatively breeding mammal

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    Conflict between rival groups is rife in nature. While recent work has begun exploring the behavioural consequences of this intergroup conflict, studies have primarily considered just the 1–2 h immediately after single interactions with rivals or their cues. Using a habituated population of wild dwarf mongooses (Helogale parvula), we conducted week-long manipulations to investigate longer-term impacts of intergroup conflict. Compared to a single presentation of control herbivore faeces, one rival-group faecal presentation (simulating a territorial intrusion) resulted in more within-group grooming the following day, beyond the likely period of conflict-induced stress. Repeated presentations of outsider cues led to further changes in baseline behaviour by the end of the week: compared to control weeks, mongooses spent less time foraging and foraged closer to their groupmates, even when there had been no recent simulated intrusion. Moreover, there was more baseline territorial scent-marking and a higher likelihood of group fissioning in intrusion weeks. Consequently, individuals gained less body mass at the end of weeks with repeated simulated intrusions. Our experimental findings provide evidence for longer-term, extended and cumulative, effects of an elevated intergroup threat, which may lead to fitness consequences and underpin this powerful selective pressure

    Is the personal always political? Education and political knowledge strengthen the relationship between openness and conservatism

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    Abstract. Research demonstrates that the negative relationship between Openness to Experience and conservatism is heightened among the informed. We extend this literature using national survey data (Study 1; N = 13,203) and data from students (Study 2; N = 311). As predicted, education – a correlate of political sophistication – strengthened the negative relationship between Openness and conservatism (Study 1). Study 2 employed a knowledge-based measure of political sophistication to show that the Openness × Political Sophistication interaction was restricted to the Openness aspect of Openness. These studies demonstrate that knowledge helps people align their ideology with their personality, but that the Openness × Political Sophistication interaction is specific to one aspect of Openness – nuances that are overlooked in the literature. </jats:p

    Increased central auditory gain and decreased parvalbumin-positive cortical interneuron density in the Df1/+ mouse model of schizophrenia correlate with hearing impairment

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    Background Hearing impairment is a risk factor for schizophrenia. Patients with 22q11.2 Deletion Syndrome (22q11.2DS) have a 25-30% risk of schizophrenia, and up to 60% also have varying degrees of hearing impairment, primarily from middle ear inflammation. The Df1/+ mouse model of 22q11.2DS recapitulates many features of the human syndrome, including schizophrenia-relevant brain abnormalities and high inter-individual variation in hearing ability. However, the relationship between brain abnormalities and hearing impairment in Df1/+ mice has not been examined. Methods We measured auditory brainstem responses (ABRs), cortical auditory evoked potentials, and/or cortical parvalbumin-positive (PV+) interneuron density in over 70 adult mice (32 Df1/+, 39 wild-type). We also performed longitudinal ABR measurements in an additional 20 animals (13 Df1/+, 7 wild-type) from 3 weeks of age. Results Electrophysiological markers of central auditory excitability were elevated in Df1/+ mice. PV+ interneurons, which are implicated in schizophrenia pathology, were reduced in density in auditory cortex but not secondary motor cortex. Both auditory brain abnormalities correlated with hearing impairment, which affected approximately 60% of adult Df1/+ mice and typically emerged before 6 weeks of age. Conclusions In the Df1/+ mouse model of 22q11.2DS, abnormalities in central auditory excitability and auditory cortical PV+ immunoreactivity correlate with hearing impairment. This is the first demonstration of cortical PV+ interneuron abnormalities correlating with hearing impairment in a mouse model of either schizophrenia or middle ear inflammation
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