237 research outputs found

    Spectral Clustering for Optical Confirmation and Redshift Estimation of X-ray Selected Galaxy Cluster Candidates in the SDSS Stripe 82

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    We develop a galaxy cluster finding algorithm based on spectral clustering technique to identify optical counterparts and estimate optical redshifts for X-ray selected cluster candidates. As an application, we run our algorithm on a sample of X-ray cluster candidates selected from the third XMM-Newton serendipitous source catalog (3XMM-DR5) that are located in the Stripe 82 of the Sloan Digital Sky Survey (SDSS). Our method works on galaxies described in the color-magnitude feature space. We begin by examining 45 galaxy clusters with published spectroscopic redshifts in the range of 0.1 to 0.8 with a median of 0.36. As a result, we are able to identify their optical counterparts and estimate their photometric redshifts, which have a typical accuracy of 0.025 and agree with the published ones. Then, we investigate another 40 X-ray cluster candidates (from the same cluster survey) with no redshift information in the literature and found that 12 candidates are considered as galaxy clusters in the redshift range from 0.29 to 0.76 with a median of 0.57. These systems are newly discovered clusters in X-rays and optical data. Among them 7 clusters have spectroscopic redshifts for at least one member galaxy.Comment: 15 pages, 7 figures, 3 tables, 1 appendix, Accepted by Journal of "Astronomy and Computing

    Glasgow Coma Scale versus Full Outline of Unresponsiveness Scale in Predicting Discharge Outcomes of Traumatic Brain Injury

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    Context: Neurological assessment is an essential element of early warning scores used to recognize and early save the lives of critically ill patients.Aim: This study aimed to compare the Full Outline of Unresponsiveness Scale and the Glasgow Coma Scale in predicting discharge outcomes in patients with traumatic brain injury Method: A comparative research design was conducted at the Neurosurgery Intensive Care Unit in El Fayoum University Hospital. The Study recruited a purposive sample of 100 adult patients with TBI. They assessed using three tools (Patients Profile Data Form, Level of Consciousness Assessment," and Tool Discharge Data Assessment Record).Results: GCS is superior to the FOUR score in predicting length of stay and full recovery without any squeal, while they are the same in predicting motor disability and sensory impairment (physical impairment). FOUR score is superior to GCS in the prediction of mortality Conclusion: The FOUR score provides more neurologic details than the GCS and is a valid predictor of outcome in patients with TBI; thus, it could be considered a future prognostic model. It is recommended to use a FOUR score for predicting outcomes in patients with traumatic brain injuries as a valid predictor of discharge outcomes after traumatic brain injury

    Perirhinal cortex lesions that impair object recognition memory spare landmark discriminations

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    Rats with lesions in the perirhinal cortex and their control group learnt to discriminate between mirror-imaged visual landmarks to find a submerged platform in a watermaze. Rats initially learnt this discrimination passively, in that they were repeatedly placed on the platform in one corner of a square watermaze with walls of different appearance, prior to swimming to that same location for the first time in a subsequent probe trial. Perirhinal cortex lesions spared this passively learnt ability, despite the common visual elements shared by the guiding landmarks. These results challenge models of perirhinal function that emphasise its role in solving discriminations between stimuli with ambiguous or overlapping features, while underlining how this cortical region is often not required for spatial processes that involve the hippocampus

    Do the rat anterior thalamic nuclei contribute to behavioural flexibility?

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    The rodent anterior thalamic nuclei (ATN) are vital for spatial memory. A consideration of their extensive frontal connections suggests that these nuclei may also subserve non-spatial functions. The current experiments explored the importance of the ATN for different aspects of behavioural flexibility, including their contribution to tasks typically associated with frontal cortex. In Experiment 1, rats with ATN lesions were tested on a series of response and visual discriminations in an operant box and, subsequently, in a water tank. The tasks included assessments of reversal learning as well switches between each discrimination dimension. Results revealed a mild and transient deficit on the operant task that was not specific to any stage of the procedure. In the water tank, the lesion animals were impaired on the reversal of a spatial discrimination but did not differ from controls on any other measure. Experiment 2 examined the impact of ATN damage on a rodent analogue of the ā€˜Stroopā€™, which assesses response choice during stimulus conflict. The lesion animals successfully acquired this task and were able to use contextual information to disambiguate conflicting cue information. However, responding during the initial presentation of conflicting cue information was affected by the lesion. Taken together, these results suggest that the ATN are not required for aspects of behavioural flexibility (discrimination learning, reversals or high-order switches) typically associated with the rat medial prefrontal cortex. The results from Experiment 2 suggest that the non-spatial functions of the ATN may be more aligned with those of the anterior cingulate cortex

    Comparison between the calculated and measured dose distributions for four beams of 6 MeV linac in a human-equivalent phantom

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    Radiation dose distributions in various parts of the body are of importance in radiotherapy. Also, the percent depth dose at different body depths is an important parameter in radiation therapy applications. Monte Carlo simulation techniques are the most accurate methods for such purposes. Monte Carlo computer calculations of photon spectra and the dose ratios at surfaces and in some internal organs of a human equivalent phantom were performed. In the present paper, dose distributions in different organs during bladder radiotherapy by 6 MeV X-rays were measured using thermoluminescence dosimetry placed at different points in the human-phantom. The phantom was irradiated in exactly the same manner as in actual bladder radiotherapy. Four treatment fields were considered to maximize the dose at the center of the target and minimize it at non-target healthy organs. All experimental setup information was fed to the MCNP-4b code to calculate dose distributions at selected points inside the proposed phantom. Percent depth dose distribution was performed. Also, the absorbed dose as ratios relative to the original beam in the surrounding organs was calculated by MCNP-4b and measured by thermoluminescence dosimetry. Both measured and calculated data were compared. Results indicate good agreement between calculated and measured data inside the phantom. Comparison between MCNP-4b calculations and measurements of depth dose distribution indicated good agreement between both

    Studies on Some Parasitic Diseases in Oreochromis niloticus Fish Hatchery with Emphasis to Life Stages

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    This study was conducted on 210 Oreochromis niloticus (O. niloticus) of different life stages including (100 fry, 100 fingerlings and 10 broodstocks) obtained from a private fish hatchery at Kafer El-Sheikh Governorate, Egypt; during August 2014. The hatchery complains 30% mortality among fry and fingerlings while no mortalities was recorded among broodstocks. Parasitological examination revealed heavy infestation with Triochodina species (sp.) in all examined life stages at a prevalence rate 100%. In addition, Gyrodactylus sp. was recorded in gills of fry, fingerlings and broodstocks at a rate of 5, 12, and 10 %, respectively. Kidneys and gills of all examined life stages showed heavy infestations with Myxosporean sp., with 100 % prevalence rate. Haemogregarina sp. was described in the blood of fingerlings and gill tissues of broodstocks. Additionally, Encysted metacerceria was observed in gills of broodstocks. The recovered parasites were demonstrated hisopathologically in the gill and kidney tissues of the examined fish. The histopathological examination revealed that the infested gills exhibited serious lesions such as hyperplasia and hypertrophy of the lining epithelial cells of the gill filaments, fusion and necrosis of secondary lamellae and vasodilatation. The lining epithelium of the renal tubules showed degenerative and necrotic changes with the presence of various developmental stages of myxosporidia. In conclusion, fry and fingerlings exhibited high mortalities, while no mortality was recorded among broodstocks, regardless the intensity of infestation and severity of pathological alterations which was intense in broodstocks

    Perirhinal cortex lesions impair tests of object recognition memory but spare novelty detection

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    This article is protected by copyright. All rights reserved. Acknowledgements This work was supported by the Wellcome Trust (WT103722/Z/14/Z). The authors wish to thank L. Kinnavane and J. M. Pearce for their contributions to the manuscript. The authors confirm that they have no known conflicts of interest.Peer reviewedPublisher PD

    Lesions of retrosplenial cortex spare immediate-early gene activity in related limbic regions in the rat

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    The retrosplenial cortex forms part of a network of cortical and subcortical structures that have particular importance for spatial learning and navigation in rodents. This study examined how retrosplenial lesions affect activity in this network by visualising the expression of the immediate-early genes c-fos and zif268 after exposure to a novel location. Groups of rats with extensive cytotoxic lesions (areas 29 and 30) and rats with lesions largely confined to area 30 (dysgranular cortex) were compared with their respective control animals for levels of c-fos expression measured by immunohistochemistry. These cortical lesions had very limited effects on distal c-fos activity. Evidence of a restricted reduction in c-fos activity was seen in the septal dentate gyrus (superior blade) but not in other hippocampal and parahippocampal subareas, nor in the anterior cingulate and prelimbic cortices. Related studies examined zif268 activity in those cases with combined area 29 and 30 lesions. The only clear evidence for reduced zif268 activity following retrosplenial cell loss came from the septal CA3 area. The confined impact of retrosplenial tissue loss is notable as, by the same immediate-early gene measures, retrosplenial cortex is itself highly sensitive to damage in related limbic areas, showing a marked c-fos and zif268 hypoactivity across all of its subareas. This asymmetry in covert pathology may help to explain the apparent disparity between the severity of learning deficits after retrosplenial cortex lesions and after lesions in either the hippocampus or the anterior thalamic nuclei
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