178 research outputs found

    Flood Hazard Management in Public Mountain Recreation Areas vs. Ungauged Fluvial Basins. Case Study of the Caldera de Taburiente National Park, Canary Islands (Spain)

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    Las Angustias River is an ungauged stream in the Caldera de Taburiente National Park (Spain), where frequent intense flash-flood events occur. The aim of this research is to analyze the flood hazard at the Playa de Taburiente. Based on the limited information available (short time-series of daily precipitation), a statistical frequency analysis of 24 h rainfall was completed and the precipitation results were transformed into surface runoff. To determine if the model underestimates the flows that are generated in the basin, the dendro-geomorphological information available was used to calibrate results. The results of the HMS model were significantly lower. At this point, both the rainfall data and the rainfall-runoff model were re-analyzed to maximize the rainfall intensity values and the runoff generated (increasing the CN value for the basin). For the 1997 flood event, a 1250 m3·s−1 flood minimizes the RMSE for the disturbed tree sample; this flow value also clearly exceeds any peak flow derived from the rainfall-runoff analysis. It is only when rainfall intensity and surface runoff are maximized that the peak flows obtained approximate those associated with dendro-geomorphological data. The results highlight the difficulties of flood hazard management in ungauged torrential basins in mountain recreational areas (such as National Parks). Thus, in the absence of flow records, when considering the maximum rainfall intensity scenario may be a useful and effective tool for flood risk management

    Properties of Accretion Flows Around Coalescing Supermassive Black Holes

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    What are the properties of accretion flows in the vicinity of coalescing supermassive black holes (SBHs)? The answer to this question has direct implications for the feasibility of coincident detections of electromagnetic (EM) and gravitational wave (GW) signals from coalescences. Such detections are considered to be the next observational grand challenge that will enable testing general relativity in the strong, nonlinear regime and improve our understanding of evolution and growth of these massive compact objects. In this paper we review the properties of the environment of coalescing binaries in the context of the circumbinary disk and hot, radiatively inefficient accretion flow models and use them to mark the extent of the parameter space spanned by this problem. We report the results from an ongoing, general relativistic, hydrodynamical study of the inspiral and merger of black holes, motivated by the latter scenario. We find that correlated EM+GW oscillations can arise during the inspiral phase followed by the gradual rise and subsequent drop-off in the light curve at the time of coalescence. While there are indications that the latter EM signature is a more robust one, a detection of either signal coincidentally with GWs would be a convincing evidence for an impending SBH binary coalescence. The observability of an EM counterpart in the hot accretion flow scenario depends on the details of a model. In the case of the most massive binaries observable by the Laser Interferometer Space Antenna, upper limits on luminosity imply that they may be identified by EM searches out to z~0.1-1. However, given the radiatively inefficient nature of the gas flow, we speculate that a majority of massive binaries may appear as low luminosity AGN in the local universe.Comment: Revised version accepted to Class. Quantum Grav. for proceedings of 8th LISA Symposium. 15 pages, 3 figures, includes changes suggested in referee report

    Temporal Retinal Nerve Fiber Loss in Patients with Spinocerebellar Ataxia Type 1

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    BACKGROUND: Autosomal dominant spinocerebellar ataxia type 1 is an adult onset progressive disorder with well characterized neurodegeneration in the cerebellum and brainstem. Beyond brain atrophy, few data exist concerning retinal and optic nerve involvement. OBJECTIVE: To evaluate retinal changes in SCA1 patients compared to age and gender matched healthy controls. METHODOLOGY/PRINCIPAL FINDINGS: Nine patients with SCA1 were prospectively recruited from the ataxia clinic and were compared to nine age and gender matched healthy controls. Both cohorts received assessment of visually evoked potentials and eye examination by optical coherence tomography to determine retinal nerve fiber layer thickness and total macular volume. While no differences were found in visually evoked potentials, SCA1 patients showed a significant reduction of mean retinal nerve fiber layer thickness (RNFLT) compared to healthy controls (84±13 µm vs. 97±8 µm, p = 0.004). Temporal areas showed the most prominent RNFLT reduction with high statistical significances (temporal-inferior: p<0.001, temporal: p<0.001, temporal-superior: p = 0.005) whereas RNFLT in nasal areas was in the range of the control group. From six SCA1 patients an additional macular scan was obtained. The comparison to the corresponding healthy control showed a slight but not significant reduction in TMV (8.22±0.68 mm(3) vs. 8.61±0.41 mm(3), p = 0.15). CONCLUSION: In SCA1 patients, we found evidence for degeneration of retinal nerve fibers. The temporal focus of the observed retinal nerve fiber layer reduction suggests an involvement of the papillo-macular bundle which resembles pathology found in toxic or mitochondrial optic nerve disease such as Leber's hereditary optic neuropathy (LHON) or dominant optic atrophy (DOA)

    Exploring the clinical features of narcolepsy type 1 versus narcolepsy type 2 from European Narcolepsy Network database with machine learning

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    Narcolepsy is a rare life-long disease that exists in two forms, narcolepsy type-1 (NT1) or type-2 (NT2), but only NT1 is accepted as clearly defined entity. Both types of narcolepsies belong to the group of central hypersomnias (CH), a spectrum of poorly defined diseases with excessive daytime sleepiness as a core feature. Due to the considerable overlap of symptoms and the rarity of the diseases, it is difficult to identify distinct phenotypes of CH. Machine learning (ML) can help to identify phenotypes as it learns to recognize clinical features invisible for humans. Here we apply ML to data from the huge European Narcolepsy Network (EU-NN) that contains hundreds of mixed features of narcolepsy making it difficult to analyze with classical statistics. Stochastic gradient boosting, a supervised learning model with built-in feature selection, results in high performances in testing set. While cataplexy features are recognized as the most influential predictors, machine find additional features, e.g. mean rapid-eye-movement sleep latency of multiple sleep latency test contributes to classify NT1 and NT2 as confirmed by classical statistical analysis. Our results suggest ML can identify features of CH on machine scale from complex databases, thus providing 'ideas' and promising candidates for future diagnostic classifications.</p

    Periodontal status of rheumatoid arthritis patients in khartoum state

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    <p>Abstract</p> <p>Background</p> <p>Few studies have investigated the periodontal condition among Rheumatoid arthritis in Sudan. The present study described the periodontal condition among Sudanese patients suffering from rheumatoid arthritis and to compare them with those of non-rheumatic subjects.</p> <p>Methods</p> <p>A group of eighty rheumatoid arthritis patients was selected from Patient's Rheumatoid Clinics in Khartoum State during the period of January to May 2010. A control group of eighty patients with the same age and gender was selected for the study. Both Rheumatoid arthritis patients and the control group were examined for their plaque index, gingival index, and clinical attachment loss.</p> <p>Results</p> <p>The results revealed that there were no significant differences in plaque and gingival index among study and control groups, with mean plaque index of (1.25 ± 0.4) for patients and (1.17 ± 0.28) for the control group (p-value is 0.3597). The mean gingival index was (1.2 ± 0.24) for the patients and (1.2 ± 0.33) for the control (p = is 0.3049). The results showed statistically significant differences in clinical attachment loss between study and control groups, with mean clinical attachment loss of (1.03 ± 0.95) for the study group and (0.56 ± 0.63) for the control group (p = 0.0002). The study revealed that no association exists between the type of drug used to treat rheumatoid arthritis (NSAIDs & DMARDs) and the periodontal parameters (plaque index, gingival index, and clinical attachment loss).</p> <p>Conclusion</p> <p>A significant relationship between periodontal disease and Rheumatoid Arthritis does exist, but no difference between plaque and gingival index has been detected among study and control groups.</p

    The CPT1C 5′UTR Contains a Repressing Upstream Open Reading Frame That Is Regulated by Cellular Energy Availability and AMPK

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    BACKGROUND: Translational control is utilized as a means of regulating gene expression in many species. In most cases, posttranscriptional regulatory mechanisms play an important role in stress response pathways and can lead to dysfunctional physiology if blocked by mutations. Carnitine Palmitoyltransferase 1 C (CPT1C), the brain-specific member of the CPT 1 family, has previously been shown to be involved in regulating metabolism in situations of energy surplus. PRINCIPAL FINDINGS: Sequence analysis of the CPT1C mRNA revealed that it contains an upstream open reading frame (uORF) in the 5' UTR of its mRNA. Using CPT1C 5' UTR/luciferase constructs, we investigated the role of the uORF in translational regulation. The results presented here show that translation from the CPT1C main open reading frame (mORF) is repressed by the presence of the uORF, that this repression is relieved in response to specific stress stimuli, namely glucose deprivation and palmitate-BSA treatment, and that AMPK inhibition can relieve this uORF-dependent repression. SIGNIFICANCE: The fact that the mORF regulation is relieved in response to a specific set of stress stimuli rather than general stress response, hints at an involvement of CPT1C in cellular energy-sensing pathways and provides further evidence for a role of CPT1C in hypothalamic regulation of energy homeostasis

    IVRIPARC project: a method for assessing the impact of global change on geoheritage of the Canary Islands national parks (Spain)

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    El patrimonio geológico y la geodiversidad de los parques nacionales contribuyen, junto con la biodiversidad, para que sean espacios naturales protegidos únicos en el país, pero también únicos a nivel mundial. El patrimonio geológico es de carácter no renovable, de tal forma que, si se pierden o degradan, lo hacen para siempre. Ante el escenario del cambio global, el patrimonio geológico de los parques nacionales canarios es muy vulnerable a los impactos rovocados por los cambios en la temperatura, avenidas torrenciales, tormentas extremas, sequías, desertificación y ascenso del nivel del mar, fundamentalmente, y a los impactos derivados de la actividad humana. Estos fenómenos provocan la activación de procesos geológicos que afectan directamente a su conservación, de tal forma que es necesario identificar los Lugares de Interés Geológico más amenazados, evaluar su incidencia y establecer los indicadores a escala de cada parque nacional para realizar su seguimiento. Conocer el estado de conservación actual, su vulnerabilidad y sus amenazas directas contribuirá a la gestión de los parques para el proceso de adaptación y mitigación del cambio global.The geoheritage and geodiversity of the national parks contribute, together with biodiversity, to make them protected natural areas that are unique in Spain, but also unique worldwide. Geoheritage is non-renewable and if it is lost or degraded it does so forever. Under the Global Change and Climate Change scenario, the geoheritage of the Canary national parks is highly vulnerable to the impacts caused by changes in temperature, flash floods, extreme storms, droughts, desertification, fires and sea level rise, fundamentally and to the impacts directly derived from human activity. These phenomena trigger the activation of geological processes that directly affect their conservation, in such a way that it is necessary to identify the geosites most threatened, to evaluate their impact and to establish the indicators at the scale of each national park for monitoring them. The knowledge of the current conservation status of geoheritage, its vulnerability and its direct threats will contribute to the management of the national parks for the process of adaptation and mitigation of Global Change.Depto. de Geodinámica, Estratigrafía y PaleontologíaDepto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEOrganismo Autónomo de Parques Nacionalespu

    Higher levels of glutamate in the associative-striatum of subjects with prodromal symptoms of schizophrenia and patients with first-episode psychosis

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    The glutamatergic and dopaminergic systems are thought to be involved in the pathophysiology of schizophrenia. Their interaction has been widely documented and may have a role in the neurobiological basis of the disease. The aim of this study was to compare, using proton magnetic resonance spectroscopy (1H-MRS), glutamate levels in the precommissural dorsal-caudate (a dopamine-rich region) and the cerebellar cortex (negligible for dopamine) in the following: (1) 18 antipsychotic-naïve subjects with prodromal symptoms and considered to be at ultra high-risk for schizophrenia (UHR), (2) 18 antipsychotic-naïve first- episode psychosis patients (FEP), and (3) 40 age- and sex- matched healthy controls. All subjects underwent a 1H-MRS study using a 3Tesla scanner. Glutamate levels were quantified and corrected for the proportion of cerebrospinal fluid and percentage of gray matter in the voxel. The UHR and FEP groups showed higher levels of glutamate than controls, without differences between UHR and FEP. In the cerebellum, no differences were seen between the three groups. The higher glutamate level in the precommissural dorsal-caudate and not in the cerebellum of UHR and FEP suggests that a high glutamate level (a) precedes the onset of schizophrenia, and (b) is present in a dopamine-rich region previously implicated in the pathophysiology of schizophrenia.peer-reviewe
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