We report on the first detection of very high-energy gamma-ray emission from the Crab Nebula by a Cherenkov telescope in dual-mirror Schwarzschild-Couder (SC) configuration. This result has been ...achieved by means of the 4 m ASTRI-Horn telescope, operated on Mt. Etna, Italy, and developed in the context of the Cherenkov Telescope Array Observatory preparatory phase. The dual-mirror SC design is aplanatic and characterized by a small plate scale, which allows us to implement large cameras with a large field of view, with small-size pixel sensors and a high level of compactness. The curved focal plane of the ASTRI camera is covered by silicon photo-multipliers, managed by an unconventional front-end electronic system that is based on a customized peak-sensing detector mode. The system includes internal and external calibration systems, hardware and software for control and acquisition, and the complete data archiving and processing chain. These observations of the Crab Nebula were carried out in December 2018 during the telescope verification phase for a total observation time (after data selection) of 24.4 h, equally divided between on- and off-axis source exposure. The camera system was still under commission and its functionality was not yet completely exploited. Furthermore, due to recent eruptions of the Etna Volcano, the mirror reflection efficiency was reduced. Nevertheless, the observations led to the detection of the source with a statistical significance of 5.4
σ
above an energy threshold of ∼3 TeV. This result provides an important step toward the use of dual-mirror systems in Cherenkov gamma-ray astronomy. A pathfinder mini-array based on nine ASTRI-like telescopes with a large field-of-view is in the course of implementation.
Abstract Background Seasonal peaks in acute myocardial infarction (AMI) incidence have been widely reported. Weather has been postulated to be one of the elements at the basis of this association. ...The aim of our study was to determine the influence of seasonal variations and weather on AMI hospital admissions. Methods We correlated the daily number of AMI cases admitted to a western Sicily hospital over twelve years and weather conditions on a day-to-day basis. Information on temperature, humidity, wind force and direction, precipitation, sunny hours and atmospheric pressure was obtained from the local Birgi Air Force base. A total of 3918 consecutive patients were admitted with AMI over the period 1987–1998 (2822 men, 1096 women; M/F: 2,58). Results and conclusions A seasonal variation was found with a significant winter peak. The results of multivariate Poisson analysis show in both sexes a significant association as regards the incidence relative ratio between the daily number of AMI hospital admission and minimal daily temperature and maximal daily humidity. The incidence relative ratios (95% confidence intervals) were, in males, 0.95 (0.92–0.98) ( p < 0.001) as regards minimal temperature and 0.97 (0.94–0.99) ( p = 0.017) as regards maximal humidity. The corresponding values in females were respectively 0.91 (0.86–0.95) ( p < 0.001) and 0.94 (0.90–0.98) ( p = 0.009). Environmental temperature, and also humidity, may play an important role in the pathogenesis of AMI. These data may help in understanding the mechanisms whereby AMI events are triggered and in organizing better the assistance to ischemic patients throughout the year.
Background: Seasonal peaks in cardiovascular disease incidence have been widely reported, suggesting weather has a role.
Design The aim of our study was to determine the influence of climatic ...variables on angina pectoris hospital admissions.
Methods: We correlated the daily number of angina cases admitted to a western Sicilian hospital over a period of 12 years and local weather conditions (temperature, humidity, wind force and direction, precipitation, sunny hours and atmospheric pressure) on a day-to-day basis. A total of 2459 consecutive patients were admitted over the period 1987–1998 (1562 men, 867 women; M/F – 1:8).
Results: A seasonal variation was found with a noticeable winter peak. The results of Multivariate Poisson analysis showed a significant association between the daily number of angina hospital admission, temperature, and humidity. Significant incidence relative ratios (95% confidence intervals/measure unit) were, in males, 0.988 (0.980–0.996) (p = 0.004) for minimal temperature, 0.990 (0.984–0.996) (p = 0.001) for maximal humidity, and 1.002 (1.000–1.004) (p = 0.045) for minimal humidity. The corresponding values in females were 0.973 (0.951–0.995) (p < 0.017) for maximal temperature and 1.024 (1.001–1.048) (p = 0.037) for minimal temperature.
Conclusions: Environmental temperature and humidity may play an important role in the pathogenesis of angina, although it seems different according to the gender. These data may help to understand the mechanisms that trigger ischemic events and to better organize hospital assistance throughout the year.
Performance and applications of the UVscope instrument Maccarone, M.C.; Catalano, O.; Giarrusso, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Volume:
659, Issue:
1
Journal Article
Peer reviewed
UVscope is a portable multi-pixels photon detector developed at IASF-Pa to support experimental activities in the high-energy astrophysics and cosmic rays field. The instrument, working in single ...photon counting mode, is designed to directly measure light flux in the wavelengths range 300–650nm. Thanks to its features and operational flexibility, the instrument can be used in a wide field of applications where the knowledge of the environmental luminosity is required, as in the characterization of sites for ground-based Cherenkov and fluorescence telescopes, and for cross-calibration of their cameras.
The present version of UVscope is based on a Multi Anode Photo Multiplier Tube and it is completed by a motorized mount and a filter wheel which allow to make low-light measurements, at programmed pointing directions and at different filter wavelengths. In this paper, the instrument is firstly presented in all its components; then the procedures adopted for its absolute and relative calibration are detailed. The performance of UVscope is evaluated and, finally, current and planned scientific applications are described.
Soybean (
Glycine max
L.) and canola (
Brassica napus
L.) seeds contain polyunsaturated fatty acids such as omega-3 and omega-9, which are important for the prevention of cardiovascular disease and ...the control of LDL cholesterol, leading to scientific interest in extracting and characterizing these lipids. To prevent the degradation of polyunsaturated fatty acids, lipid extraction should be done cold. A "new-method" for cold lipid extraction has been developed, which uses low toxicity solvents such as hexane and ethanol. This method aims to replace chloroform and methanol widely used in the Bligh & Dyer method. By employing the new method, which uses ethanol, hexane and water in the ratio of 2.5 : 2.5 : 1, an average of 28% canola and 16% soybean total lipids were extracted, and the mono- and polyunsaturated fatty acids did not suffer degradation. The amount of lipid extracted by the new method was compared with the Soxhlet and Bligh & Dyer methods. The new method uses low-toxicity solvents for lipid extraction, and the accuracy values range between 103.33% and 107.51%, proving it to be an efficient method.
A fast, easy lipid extraction method using low-toxicity solvents is developed in this study for oilseed samples rich in polyunsaturated fatty acid.
ABSTRACT
The alkaline hydrolysis of a series of homologous reactants constituted by two reactive centers bridged by a methylene spacers chain, the 1,n‐bis(2‐azidepyridinium)alkanes (n = 3, 4, 5, 6, ...and 8), is investigated. The reaction under pseudo–first‐order condition was followed by ultraviolet–visible spectrophotometry. The presence of clear isosbestic point suggests the absence of stable intermediates. However, the intermediates 1‐(2‐azidepyridinium), n‐(2‐pyridone)alkanes (monocationic compounds), were isolated and characterized as well the reaction end products 1,n‐(2‐pyridone)alkanes (noncharged compounds). The kinetic analysis fitted to a two‐step consecutive reaction, where the k1/k2 values demonstrate the larger reactivity of the first step over the second one, especially for shorter bridged reactants. The OH− reaction order is one for each step. Although Debye–Hückel law was obeyed, the experimental point at ionic strength zero is much higher than the extrapolated one. In addition, the k1 values substantially decrease as KCl is added especially for shorter homologous whereas the effect on k2 is almost negligible. Simple charge density effects as a function of the spacer's length do not explain the observations. On the other hand, from the pronounced anion selectivity inhibition effects on k1 for the shorter derivatives, the existence of an equilibrium involving a conformer, a “sandwich‐type” complex with the OH− between the two pyridinium rings, with an “open‐stretched” conformer is proposed. For short‐bridged reactants, the complex conformer prevails whereas for long‐bridged compounds the stretched structure prevails. The results in acetonitrile/water seem to reflect changes in the equilibrium. The reaction is controlled by the balance between enthalpy and entropy. The contribution of the activation entropy in a short‐bridged reactant is higher than the long‐bridged one, which suggests an activated complex with high structural organization in the first reactants.
The human arcuate nucleus (ARCn) is postulated to be homologous to ventral medullary cells involved in chemoreception, and respiratory and blood pressure responses. Abnormalities in central ...respiratory control may result from dysfunction of this anatomic ventral area. We evaluated the changes of the neuronal population of the medullary ARCn in infants victims of the sudden infant death syndrome (SIDS). In this study we tested the hypothesis that anatomical deficiency of the ARCn is associated with SIDS. The volume and neuronal density of the ARCn were morphometrically quantified with an image analyzer in 36 cases of SIDS and 12 age-matched controls. We found a marked hypoplasia in the SIDS ARCn compared to controls and, particularly, in 11 SIDS cases (30%) in which the ARCn exhibited a severe hypoplasia, being almost totally absent. Three-dimensional reconstructions and morphometric measurements of ARCn confirmed this marked hypoplasia in all the serial sections examined (P = 0.0001) and the reduced neuronal density (P = 0.0025) in relation to control cases. In conclusion these abnormalities observed in the ARCn are consistent with the idea that ARCn dysfunction plays an important role among the causative factors of sudden infant death. The hypoplasia of the ARCn represents the most frequent congenital abnormality in our experience, and can be a plausible morphological substrate for a subset of SIDS.
In the present study we investigated quantitatively the incidence of hypoplasia of the arcuate nucleus (ARCn) of the medulla oblongata, reported earlier Gozal D, Hathout GM, Kirlew KAT (1994) J Appl ...Physiol 76:207, as well as its distribution in 62 cases of sudden infant death syndrome (SIDS; mean age 14 postnatal weeks, 39 male and 23 female) and 25 controls (mean age 16 postnatal weeks, 14 male and 11 female), using detailed histopathological and morphometric analyses performed on serial sections of medulla oblongata. The SIDS cases were divided into four subtypes: SIDS A (27 cases, 43%) with histologically well-developed ARCn; SIDS B (16 cases, 26%) with severe bilateral hypoplasia along the whole length; SIDS C (11 cases, 18%) with partial bilateral hypoplasia, located mainly in the lateral portions of the caudal two thirds of the nucleus, and SIDS D (8 cases, 13%) with right monolateral hypoplasia of the ARCn. ARCn hypoplasia was detected in 56% of cases (35 cases). Three-dimensional volume reconstruction showed that in the SIDS A victims the mean volume was analogous to controls, whereas in the SIDS group with ARCn hypoplasia, severe or partial, the mean volume was significantly different from controls on both sides of the medulla oblongata (SIDS B group: P=0.003, P=0.002; SIDS C group: P=0.007, P=0.008). The mean ARCn volume in the SIDS D group was statistically significant only on the right side ( P=0.005). We also observed reduced neuron density of the ARCn, associated with a decrease in the total number of neurons over the whole length of the nucleus itself. On the basis of the morphometric results of neuronal population in the different portions of the ventrolateral medulla in SIDS cases, we hypothesized that infants without the full complement of neurons and neuropil (ARCn hypoplasia) are at risk for SIDS because they are unable to develop appropriate cardioventilatory control during this crucial developmental period.
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