471 research outputs found
Search for solar axions: CAST
No full textThe CERN Axion Solar Telescope (CAST) is searching for axions produced in the Sun's core by the Primakoff process. CAST is using a decommissioned Large Hadron Collider (LHC) test magnet where axions could be converted back into X-rays with energies up to 10 keV. Analysis of the 2003 data showed no signal above background implying an upper limit for the axion-photon coupling constant gagg < 1.16 X 10 ^-10 GeV exp -1 at 95% C.L. for ma . 0.02 eV [1]. The higher quality 2004 data is presently under analysis. CAST Phase II is scheduled to start in late 2005. This will be the first step in extending CAST's sensitivity to axion rest masses up to ~ 1 eV
High resolution post-mortem MRI of non-fixed in situ foetal brain in the second trimester of gestation: Normal foetal brain development
No full textPurpose: To describe normal foetal brain development with high resolution post-mortem MRI (PMMRI) of non-fixed foetal brains. Methods: We retrospectively collected PMMRIs of foetuses without intracranial abnormalities and chromosomal aberrations studied after a termination of pregnancy due to extracranial abnormalities or after a spontaneous intrauterine death. PMMRIs were performed on a 3-T scanner without any fixation and without removing the brain from the skull. All PMMRIs were evaluated in consensus by two neuroradiologists. Results: Our analysis included ten PMMRIs (median gestational age (GA): 21 weeks; range: 17–28 weeks). At 19 and 20 weeks of GA, the corticospinal tracts are recognisable in the medulla oblongata, becoming less visible from 21 weeks. Prior to 20 weeks the posterior limb of the internal capsule (PLIC) is more hypointense than surrounding deep grey nuclei; starting from 21 weeks the PLIC becomes isointense, and is hyperintense at 28 weeks. From 19–22 weeks, the cerebral hemispheres show transient layers: marginal zone, cortical plate, subplate, and intermediate, subventricular and germinal zones. Conclusion: PMMRI of non-fixed in situ foetal brains preserves the natural tissue contrast and skull integrity. We assessed foetal brain development in a small cohort of foetuses, focusing on 19–22 weeks of gestation. Key Points: • Post-mortem magnetic resonance imaging (PMMRI) of non-fixed head is feasible. • PMMRI of unfixed in situ foetal brains preserves the natural tissue contrast. • PMMRI provide a good depiction of the normal foetal brain development. • PMMRI of unfixed in situ foetal brains preserves the skull integrity. • PMMRI pattern of foetal brain development at early gestational age is described
Optic Nerve Sheath Diameter is not Related to Intracranial Pressure in Subarachnoid Hemorrhage Patients
No full textBackground: Intracranial pressure (ICP) monitoring is essential after subarachnoid hemorrhage (SAH) to prevent secondary brain insults and to tailor individualized treatments. Optic nerve sheath diameter (ONSD), measured using ultrasound (US), could serve as a noninvasive bedside tool to estimate ICP, avoiding the risks of hemorrhage or infection related to intracranial catheters. The aims of this study were twofold: first, to explore the reliability of US for measuring ONSD; second, to establish whether the US-ONSD can be considered a proxy for ICP in SAH patients early after bleeding. For the first aim, we compared the ONSD measurements given by magnetic resonance imaging (MRI-ONSD) with the US-ONSD findings. For the second aim, we analyzed the relationship between US-ONSD measurements and ICP values. Methods: Adult patients with diagnosis of aneurysmal SAH and external ventricular drainage system (EVD) were included. Ten patients were examined by MRI to assess ONSD, and the results were compared to the diameter given by US. In 20 patients, the US-ONSD values were related to ICP measured simultaneously through EVD. In ten of these patients, we explored the changes in the US-ONSD at the time of controlled and fairly rapid changes in ICP after cerebrospinal fluid (CSF) drainage. Results: US-ONSD measurements at the bedside were accurate, very similar to the diameters measured by MRI (the mean difference in the Bland–Altman plot was 0.08 mm, 95% limits of agreement: − 1.13; + 1.23 mm). No clear relationship was detectable between the ICP and US-ONSD, and a linear regression model showed an angular coefficient very close to 0 (p ' 0.05). US-ONSD and ICP values were in agreement after CSF drainage and shifts in ICP in a limited number of patients. Conclusions: US-ONSD measurement does not accurately estimate ICP in SAH patients in the intensive care unit
Neurodevelopmental outcome at 36 months in very low birth weight premature infants with MR diffuse excessive high signal intensity (DEHSI) of cerebral white matter
No full textPurpose: To understand the meaning of diffuse excessive high signal intensity (DEHSI) of white matter (WM), a frequently observed finding on MR in VLBW infants at a corrected term age. Methods: This is a retrospective study. Qualitative visual assessment of cerebral WM signal intensity on T2WI was performed by two readers on 78 VLBW infants, scanned on a 1.5 T-MRI at term equivalent age. ADC values were then measured in six regions of interest: four in frontal and parietal periventricular and two in parietal subcortical WM. Mean ADC values were then compared with qualitative visual assessment and with mean ADC values obtained ten term healthy babies. Both periventricular and subcortical mean ADC values were correlated with the neurological follow-up, evaluated with the Griffith’s mental developmental scale at 36 months. Results: There was no agreement between the visual qualitative assessment of white matter DEHSI and corresponding ADC values (P values = 0.42 for periventricular WM; P values = 0.18 for subcortical WM). Mean ADC values were higher in preterms than in term babies (P values <0.001). No significant correlation was found between ADC values and the developmental quotient at 36 months (P values >0.05). Conclusions: DEHSI in VLBW infants is a MR finding poorly defined with conventional T2 MRI. The presence of T2 hyperintensities weakly correlates with ADC, and ADC values are not associated with the neurological long-term outcome at 3 years, demonstrating that DEHSI should not be considered as a WM disease
Petrarca politico e Seneca tragico (ms. Escorialensis T III 11): natura e società tra centro e margine
No full textIl testo delle Tragoediae di Seneca, che Petrarca leggeva nel ms. Escorialensis T III 11 e in altri esemplari perduti, è il centro semantico attorno al quale il poeta sviluppa riflessioni su fatti della storia del Trecento consonanti con alcuni episodi dei drammi latini posti in evidenza tramite marginalia. Di questo rapporto dialettico tra testo senecano, annotazioni marginali e opere di Petrarca si rende conto affrontando i seguenti temi. 1. Sovrani esecrabili: Atreo, Eteocle e Polinice dalle Tragoediae al XIV sec.; la superbia dei regnanti. 2. Società e corruzione: Avignone, Roma e i conflitti europei tra Seneca e Petrarca. 3. Natura ribelle: l’ekpyrosis di Seneca e l’apocalisse del Trecento. 4. Fuga nella natura, vita al margine: Hippolytus, Silvius, Silvanus
High resolution positron Q-value measurements and nuclear structure studies far from the stability line. Progress report
No full textResearch progress in briefly described, and details are presented in the attached preprints and reprints: (1) precision mass differences in light rubidium and krypton isotopes utilizing beta endpoint measurements; (2) precision mass measurements utilizing beta endpoints; (3) Monte Carlo calculations predicting the response of intrinsic GE detectors to electrons and positrons; and (4) reactor antineutrino spectra and nuclear spectroscopy of isotopes far from beta stability. (WHK
High resolution positron Q-value measurements and nuclear structure studies far from the stability line. Progress report, July 1, 1979-June 30, 1980. [Dept. of Physics and Astronomy, Univ. of South Carolina, Columbia]
No full textThis document represents a progress report and renewal proposal for the contract DEAS 09 79 ER10434 between the USDOE and USC. During the time from 1 July 1979 to 1 March 1980, the large 35% intrinsic Ge detector was purchased and tested, and the new hyperpure Ge detector for positron end-point-energy measurements was designed and fabricated by ORTEC. It was delivered just prior to January 1, 1980. Measurements using this special equipment began in January 1980. During this period, a new effort in the measurement of short nuclear lifetimes was completed, and nuclear structure measurements of /sup 206/Rn nd /sup 208/Rn were completed. The results of these efforts are described in the text. A search for the Post Doctoral Research Associate was started last summer and the position will be filled on or about 1 March 1980. The first experiments to measure positron end-point-energies were proposed to the ORIC scheduling committee, and measurements will begin in March 1980. Theoretical efforts describe accurately the interference of annihilation radiation with positron end-point-energy measurements were begun
Multiparametric MR imaging of Parkinsonisms at 3 tesla : Its role in the differentiation of idiopathic Parkinson's disease versus atypical Parkinsonian disorders
No full textObjectives: The Nigrosome-1 and putaminal hypointensity depicted on susceptibility-weighted imaging (SWI), and midbrain atrophy assessed on T1-weighted are some of the most common radiological parameters to diagnose Parkinsonism at Magnetic Resonance (MR) imaging. Our aim is to assess the feasibility of these signs in the differentiation of Idiopathic Parkinson's disease (IPD) patients versus disease (DC) and healthy controls (HC) and in the assessment of the Atypical Progressive Parkinsonisms (APPs). Methods: Presence or loss of the Nigrosome-1 was assessed retrospectively on multiple-echo SWI obtained on a 3 T scan by two neuroradiologists. Results were compared with the 123I-FP-CIT SPECT images. Morphologic diagnostic features suggestive of APPs such as midbrain atrophy and putaminal hypointensity were evaluated by qualitative scores. The midbrain and putaminal scores were summed (combined score) and then added to the Nigrosome-1 score (global score). Results: The study included 126 patients with IPD (n = 56), APPs patients (n = 30; 18 PSP, 3 MSA-C, 9 MSA-P), 16 DC and 24 HC. Sensitivity and specificity of the Nigrosome-1 in discriminating IPD from controls were 96,43% and 85.00%, APPs from controls were 100% and 85%, IPD from APPs were 96,43% and 0% respectively. Combined score for midbrain atrophy and putaminal hypointensity resulted in the most accurate for distinguishing APPs from IPD with a value of ≥ 2 (AUC = 0.98). Conclusion: Nigrosome-1 is a valid tool to differentiate IPD-APPs from controls. The combined score of midbrain atrophy and putaminal hypointensity represents a valid diagnostic pointer in the differential diagnosis of APPs from IPD
Inelastic WIMP-nucleus scattering to the first excited state in (125)Te
No full textThe direct detection of dark matter constituents, in particular the weakly
interacting massive particles (WIMPs), is considered central to particle physics and cosmology. In this paper we study transitions to the excited states, possible in nuclei which have sufficiently low-lying excited states. Examples considered previously were the first excited states of ¹²⁷I, ¹²⁹Xe and ⁸³Kr. Here, we examine ¹²⁵Te, which offers some advantages and is currently being considered as a target. In all these cases the extra signature of the gamma rays following the de-excitation of these states has definite advantages over the purely nuclear recoil and in principle such a signature can be exploited experimentally. A brief discussion of the experimental feasibility is given in the context of the CUORE experiment.J D Vergados, F T Avignone Iii, M Kortelainen, P Pirinen, P C Srivastava, J Suhonen and A W Thoma
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