245Cm fission cross section measurement in the thermal energy region

A new cross section measurement for the ^245Cm(n,f) reaction in the thermal energy region has been performed at the GELINA neutron facility of the Institute for Reference Materials and Measurements (IRMM) in Geel, Belgium. The energy of the neutrons is determined applying the time of flight method using a flight path length of about 9 m. In the present work, the incident neutron energy covers 10 meV up to a few eV. A 98.48% enriched ^245Cm sample was mounted back-to-back with a ^10B sample in the centre of a vacuum chamber together with two surface barrier detectors positioned outside the neutron beam. One detector measured the ^10B(n,a)^7Li reaction products for the neutron flux determination, while the second one registered the ^245Cm(n,f) fragments. In this way, the neutron flux can be determined simultaneously with the fission fragments. A control measurement has been performed replacing the ^245Cm sample with a ^235U sample in order to check that the well-known ^235U(n,f) cross section can be reproduced. Our measurement yielded a ^245Cm(nth,f) cross section of 2131±43±173 b and a Westcott factor gf=0.939±0.019

Cerebrospinal fluid and blood flow in mild cognitive impairment and Alzheimer's disease: a differential diagnosis from idiopathic normal pressure hydrocephalus

<p>Abstract</p> <p>Background</p> <p>Phase-contrast magnetic resonance imaging (PC-MRI) enables quantification of cerebrospinal fluid (CSF) flow and total cerebral blood (tCBF) flow and may be of value for the etiological diagnosis of neurodegenerative diseases. This investigation aimed to study CSF flow and intracerebral vascular flow in patients with Alzheimer's disease (AD) and patients with amnesic mild cognitive impairment (a-MCI) and to compare the results with patients with idiopathic normal pressure hydrocephalus (NPH) and with healthy elderly volunteers (HEV).</p> <p>Methods</p> <p>Ten a-MCI and 9 mild AD patients were identified in a comprehensive neurological and neuropsychological assessment. They underwent brain MRI; PC-MRI pulse sequence was performed with the following parameters: two views per segment; flip angle: 25° for vascular flow and 20° for CSF flow; field-of-view (FOV): 14 × 14 mm²; matrix: 256 × 128; slice thickness: 5 mm; with one excitation for exams on the 3 T machine, and 2 excitations for the 1.5 T machine exams. Velocity (encoding) sensitization was set to 80 cm/s for the vessels at the cervical level, 10 or 20 cm/s for the aqueduct and 5 cm/s for the cervical subarachnoid space (SAS). Dynamic flow images were analyzed with in-house processing software. The patients' results were compared with those obtained for HEVs (n = 12), and for NPH patients (n = 13), using multivariate analysis.</p> <p>Results</p> <p>Arterial tCBF and the calculated pulsatility index were significantly greater in a-MCI patients than in HEVs. In contrast, vascular parameters were lower in NPH patients. Cervical CSF flow analysis yielded similar values for all four populations. Aqueductal CSF stroke volumes (in μl per cardiac cycle) were similar in HEVs (34 ± 17) and AD patients (39 ± 18). In contrast, the aqueductal CSF was hyperdynamic in a-MCI patients (73 ± 33) and even more so in NPH patients (167 ± 89).</p> <p>Conclusion</p> <p>Our preliminary data show that a-MCI patients present with high systolic arterial peak flows, which are associated with higher mean total cerebral arterial flows. Aqueductal CSF oscillations are within normal range in AD and higher than normal in NPH. This study provides an original dynamic vision of cerebral neurodegenerative diseases, consistent with the vascular theory for AD, and supporting primary flow disturbances different from those observed in NPH.</p

Sleep apnea syndrome in an elderly population admitted to a geriatric unit : prevalence and effect on cognitive function

International audienceBackground Sleep apnea leads to cognitive impairment in older patients, but its association with neurodegeneration remains controversial, and most studies do not distinguish between the more common obstructive form (OSAS) and the rarer central form (CSAS). Objective The purpose of this study was to assess the prevalence of the different forms of sleep apnea in a cohort of cognitively impaired elderly patients (>70 years) and to investigate their associations with cognitive deficit, weighted against known risk factors for neurodegeneration. Methods Overnight polygraphy was performed for 76 consecutive patients admitted to our geriatric unit. Their cognitive function was assessed using the Mini Mental-State Exam (MMSE), Mattis Dementia Rating Scale (MDRS) and Stroop test. Multivariable analyses were performed to determine associations between cognitive function and independent variables describing demographics, sleep apnea measures, and cardiovascular risk factors. Results The cohort comprised 58 women and 18 men aged a mean of 84 years (range, 73-96). Sleep apnea syndrome (SAS) was diagnosed in 48 patients (63%), of which 31 (41%) with OSAS and 17 (22%) with CSAS. Multivariable regression analysis revealed that MDRS was lower in patients with OSAS (beta = -10.03, p = 0.018), that Stroop Colors and Words delays increased with AHI (beta = 0.17, p = 0.030 and beta = 0.31, p = 0.047) and that that Stroop Interference delay was higher in patients with CSAS (beta = 24.45, p = 0.002). Conclusion Sleep apnea is thus highly prevalent in elderly patients with cognitive impairment. OSAS was associated with lower general cognitive function, while CSAS was only associated with increased Stroop Interference delays. Elderly patients with cognitive deficit could benefit from sleep apnea screening and treatment

Constraints on the dipole photon strength for the odd uranium isotopes

Nuclear level densities (NLDs) and photon strength functions (PSFs), also called ¿ -ray or radiation strength functions, represent average properties of the nucleus in the regime of excitation where individual levels and transition probabilities by ¿ decay are not readily accessible by experimental or theoretical means. They are key ingredients for statistical calculations of the reaction cross sections involving ¿ rays via the Hauser-Feshbach approach [1], like inelastic scattering or neutron capture reactions.Peer ReviewedAquest article té 124 autors/autores J. Moreno-Soto, S. Valenta, E. Berthoumieux, A. Chebboubi, M. Diakaki, W. Dridi, E. Dupont, F. Gunsing, M. Krticka, O. Litaize, O. Serot, O. Aberle, V. Alcayne, S. Amaducci, J. Andrzejewski, L. Audouin, V. Bécares, V. Babiano-Suarez, M. Bacak, M. Barbagallo, Th. Benedikt, S. Bennett, J. Billowes, D. Bosnar, A. Brown, M. Busso, M. Caamaño, L. Caballero-Ontanaya, F. Calviño, M. Calviani, D. Cano-Ott, A. Casanovas, F. Cerutti, E. Chiaveri, N. Colonna, G. Cortés, M. A. Cortés-Giraldo, L. Cosentino, Cristallo, L. A. Damone, P. J. Davies, M. Dietz, C. Domingo-Pardo, R. Dressler, Q. Ducasse, I. Durán, Z. Eleme, B. Fernández-Domínguez, A. Ferrari, P. Finocchiaro, V. Furman, K. Göbel, A. Gawlik-Rami, S. Gilardoni, I. F. Gonçalves, E. González-RomeroC. Guerrero, S. Heinitz, J. Heyse, D. G. Jenkins, A. Junghans, F. Käppeler, Y. Kadi, A. Kimura, I. Knapová, M. Kokkoris, Y. Kopatch, D. Kurtulgil, I. Ladarescu, C. Lampoudis, C. Lederer-Woods, S. J. Lonsdale, D. Macina, A. Manna, T. Martínez, A. Masi, C. Massimi, P. Mastinu, M. Mastromarco, E. A. Maugeri, A. Mazzone, E. Mendoza, A. Mengoni, V. Michalopoulou, P. M. Milazzo, F. MingroneA. Musumarra, A. Negret, R. Nolte, F. Ogállar, A. Oprea, N. Patronis, A. Pavlik, J. Perkowski, L. Piersanti, C. Petrone, E. Pirovano, I. Porras, J. Praena, J. M. Quesada, D. Ramos-Doval, T. Rauscher, R. Reifarth, D. Rochman, M. Sabaté-Gilarte, A. Saxena, P. Schillebeeckx, D. Schumann, A. Sekhar, A. G. Smith, N. V. Sosnin, P. Sprung, A. Stamatopoulos, G. Tagliente, J. L. Tain, A. Tarifeño-Saldivia, L. Tassan-Got, P. Torres-Sánchez, A. Tsinganis, J. Ulrich, S. Urlass, G. Vannini, V. Variale, P. Vaz, A. Ventura, D. Vescovi, V. Vlachoudis, R. Vlastou, A. Wallner, P. J. Woods, T. Wright, P. ŽugecPostprint (published version

Reduced CSF turnover and decreased ventricular Aβ42 levels are related

International audienceBACKGROUND: The appearance of Aβ42 peptide deposits is admitted to be a key event in the pathogenesis of Alzheimer's disease, although amyloid deposits also occur in aged non-demented subjects. Aβ42 is a degradation product of the amyloid protein precursor (APP). It can be catabolized by several enzymes, reabsorbed by capillaries or cleared into cerebrospinal fluid (CSF). The possible involvement of a decrease in CSF turnover in A4β2 deposit formation is up to now poorly known. We therefore investigated a possible relationship between a reduced CSF turnover and the CSF levels of the A4β2 peptide.To this aim, CSF of 31 patients with decreased CSF turnover were studied. These patients presented chronic hydrocephalus communicating or obstructive, which required surgery (ventriculostomy or ventriculo-peritoneal shunt). Nine subjects had idiopathic normal pressure hydrocephalus (iNPH), and the other 22 chronic hydrocephalus from other origins (oCH).The Aβ42 peptide concentration was measured by an ELISA test in 31 ventricular CSF samples and in 5 lumbar CSF samples from patients with communicating hydrocephalus. RESULTS: The 5 patients with lumbar CSF analysis had similar levels of lumbar and ventricular Aβ42. A significant reduction in Aβ42 ventricular levels was observed in 24 / 31 patients with hydrocephalus. The values were lower than 300 pg/ml in 5 out of 9 subjects with iNPH, and in 15 out of 22 subjects with oCH. CONCLUSION: The decrease of CSF Aβ42 seems to occur independently of the surgical hydrocephalus aetiology. This suggests that a CSF reduced turnover may play an important role in the decrease of CSF Aβ42 concentration