1,720,998 research outputs found
GaAs X-ray detector characterization through a 3D finite element model
No full textIn this paper the characterization of a GaAs X-ray pixel detector is presented. The performance is obtained experimentally by a detector using a Schottky diode on a semi-insulating, Vertical Gradient Freeze, (100) oriented single crystal GaAs substrate. Moreover, a new 3D Model based on the Finite Element Method is shown which takes into account the carrier trapping and emission phenomena. The model analyzes the single event upset for a photon hitting the pixel surface in any direction. The main advantage of the model used is its ability to determine the influence of both the position of the impact point and of the slope of the particle trajectory with respect to the pixel surface on the detector performance. The numerical simulations obtained confirm the experimental values and permit the indirect evaluation of the charge collection efficiency through a preliminary determination of the real trap distribution and transport parameters depending on the electric field
Comparative Analysis of GaAs, CdTe and CdZnTe Radiation Detectors
No full textIn this paper a comparative analysis of GaAs, CdTe and CdZnTe radiation detectors has been performed. The study is carried out adopting a 3D FEM model which takes into account the carrier trapping and generation phenomena by the Shockley Read Hall recombination theory. The evaluated performance is in good accordance with the known experimental values. This confirms the general validity of the adopted model in simulating devices of any material and at any working temperature
Design of High Speed Circuits for Systematic Cyclic Error Correction Codes
No full textIn this paper the design of an encoder and of a decoder for systematic Hamming codes is carried out. Full-parallel architecture is used and hardware is easy to implement, being composed of a cascade of combinational equal structures. The proposed solution allows high bit rates and high degree of modularity, so an easy integration of the circuits is possible. These characteristics make the method suitable to be adopted in a photonic environment in which clocked digital memory elements are still a critical aspect. The methodology, employed to synthesize Hamming code circuits, has a general validity: in fact, it can be adopted for every systematic cyclic code
A wireless sensor network for security systems adopting the Bluetooth technology
No full textBluetooth is a new promising short-range wireless technology designed to enable wireless communications among different devices. It has been gaining increasing interest from various industries because of its inexpensive cost, low power and small size. Compared with other wireless technologies, Bluetooth uses short data packets and a higher hop rate. This combination makes the devices enough immune to interference with radio frequency sources as well as with other users. In this paper, a l ow power, portable, and secure Bluetooth sensor system has been designed adopting an FPGA and a Bluetooth module. The system have built in security, including authentication and encryption to prevent eavesdropping. At low sampling rates, the adopted solution offers low power consumption and consequently battery with lower capacity can be adopted, minimizing the sensor system weight. With higher sampling rates, the system equipped with a FPGA offers the best architectural solution and performance. Therefore, Bluetooth can be satisfactorily adopted in many different applications such as habitat monitoring, civil infrastructure health monitoring, biomedical vital signs monitoring, data collection
Olanzapine-induced hypertriglyceridemia and Diabetes mellitus
No full textBackgroundHypertriglyceridemia (HTG), weight gain and new onset diabetes mellitus (DM) are documented side effects of olanzapine (OLZ). Case reports of OLZ-induced ketoacidosis with DM has been recently described. Weight gain often does not correlate with the severity of HTG and/or DM observed and it is difficult to delineate the direct effects of OLZ versus those associated with OLZ–induced obesity.We report a case showing improvement of lipid and glucose metabolism after discontinuation of OLZ, independent of body weight.Case recordA 36 years old white man had a 5 years history of hospitalizations for schizophrenia, with unremarkable lipid and glucose profile prior to initiation OLZ in October 2006. He had weight 90 Kg and BMI 33 Kg/m2. He initiated OLZ and started losing weight, with polydipsia and polyuria; in February 2007 a blood test disclosed HTG (1151 mg/dl), hyperglycemia (463 mg/dl), glycosuria (8902 mg/dl) and ketonuria (80 mg/dl). A subsequent blood test upon hospital admission showed TG=3298 mg/dl, glycated haemoglobin A1C=14.3%. His body weight was 76 Kg, BMI 27 Kg/m2 and waist circumference 90 cm. Serum insulin, serum and urinary C peptide, serum amylases and lipases and abdomen CT scan did not show any alteration.OLZ was discontinued and the patient put on insulin therapy and hydration. After one week we observed a complete remission of HTG (176 mg/dl) and improvement of glucose metabolism (glycaemia=249 mg/dl, glycosuria=652 mg/dl). A month after discharge, he still presented hyperglycaemia.ConclusionOur case demonstrates changes in OLZ-related HTG and DM unrelated to weight gain. The patient had no other cause of HTG so OLZ appeared to have a direct effect on lipid metabolism independently of weight gain. He had a family history of DM and it’s possible that the OLZ acted on a DM susceptibility. Future research is needed in order to understand the mechanisms related to glucose and lipid metabolism of atypical antipsychotic drugs
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