230 research outputs found
Cubesat mission with technological demonstrator payload for high data rate downlink and health monitoring
The HyperCube payload will be composed by two different technological experiment, an high data-rate C band antenna, and a demonstrator for a remote structural health monitoring system.
The first one has been thought with the aim to give Cubesats the capability to download an high quantity of data; it could be useful either if the data requiring the high data-rate downlink is on-board generated or simply retransmitted. The applications for which this payload could be used are several; an example
for the first category of application is to download the data generated by another payload; the high data-rate capability could be necessary due to the narrow visibility window with the ground station, affected also by the absence of an active AOCS subsystem, which makes difficult the alignment of the on board
antenna with the ground one. But the C band antenna could also be used to act as a “space–repeater”, downloading up–linked
information. The second payload is related to the need to
take under strictly control the health of the structures (not only the ones strictly belonging to primary structures, but also that
of any subsystem component). In order to do that, smart materials are integrated into the structural component that need to be monitored; in particular, piezoelectric patches are used as sensors. As the structure is stressed, and the integrated piezoelectric sensors are subjected to mechanical deformation, they produce an electric signal; acquiring and properly studying the produced signal it is possible to monitor the mechanical
condition of the structures. The health monitoring system is completed by a MicroController Unit which acquires, samples
and stores the signal produced, and a transmitting system, which could be the C band antenna, or the TT&C antenna which
each satellite needs
Study on an air-launched constellation of tactical micro-satellites for defence Use
The great attention on air-launched microsatellites is due on one hand to the possibilities given by the miniaturization push, making the same performances of traditional satellites achievable with smaller systems, and on the other hand to the disruptive advantages allowed by air-launch techniques, providing Italy not only with an autonomous launch capability, but also with the flexibility to choose the orbit inclination and the launch time, enabling a responsive approach at lower costs respect to ground based launches. In this study, several issues related to this subject are analyzed. A constellation of four microsatellites for
electro-optical Earth Observation (EO) is conceived, namely ITAFμSAT (i.e. ITalian Tactical Formation of μ-SATellites). ITAFμSAT is designed to achieve a sub-metric spatial resolution and to offer a high revisit frequency on a specified target area to satisfy military needs. ITAFμSAT is designed to be responsive and the system is conceived to guarantee a fast access to space since the mission is called, through a Plug-and-Play (PnP) approach; to provide Italy with a proprietary system, built, launched and operated on-purpose for its contingent needs; and to complete the information supplied by other EO systems with high quality images captured in a very short time
In vitro effects of tyre debris organic extract on the kinetic and morphologic traits of rabbit spermatozoa
[EN] The present study aims at evaluating the effects of the organic extract of tyre debris (TDOE) from tyre wear on the kinetic and morphologic features of rabbit spermatozoa. Rabbit sperm were incubated for 4 h with 0, 5, 10, 50 and 75 ¿g/mL of TDOE. Sperm motility was evaluated by computer-assisted semen analysis. Phosphatidilcholine (PS) externalization (apoptosis) and plasma membrane breakage (necrosis) were assessed using the annexinV/propidium iodide assay. The sperm ultrastructure was observed by scanning (SEM) and transmission electron microscopy (TEM). A relevant decrease in the motility rate, PS externalization, and in plasma membrane breakage of spermatozoa were observed after incubation with TDOE at concentrations higher than 50 ¿g/mL. The most frequent ultrastructural anomalies detected in the analysed specimens were: plasma and/or acrosomal membrane breakage, swollen and disorganized mitochondria, and altered axonemal patterns. Taken together, these results suggest that the organic extract of tyre debris can be toxic to rabbit spermatozoa ¿ affecting their movement and structural integrity ¿ when present in seminal plasma at a concentrations higher than 50 ¿g/mL. Although rabbit sperm has been proven to be a suitable model for testing the in vitro effects of many chemical compounds, including TDOE, the obtained results must be considered preliminary and cannot be extrapolated yet to the in vivo outcomes because of scanty data. The results encourage, however, further research in this field.Supported by the PROLIFE Flagship project, city of Milan, ItalyMoretti, E.; Dal Bosco, A.; Mourvaki, E.; Cardinali, R.; Collodel, G.; Geminiani, M.; Cetta, F.... (2009). In vitro effects of tyre debris organic extract on the kinetic and morphologic traits of rabbit spermatozoa. World Rabbit Science. 17(4):213-220. doi:10.4995/wrs.2009.64621322017
Development of bile duct bezoars following cholecystectomy caused by choledochoduodenal fistula formation: a case report
BACKGROUND: The formation of bile duct bezoars is a rare event. Its occurrence when there is no history of choledochoenteric anastomosis or duodenal diverticulum constitutes an extremely scarce finding. CASE PRESENTATION: We present a case of obstructive jaundice, caused by the concretion of enteric material (bezoars) in the common bile duct following choledochoduodenal fistula development. Six years after cholecystectomy, a 60-year-old female presented with abdominal pain and jaundice. Endoscopic retrograde cholangiopancreatography demonstrated multiple filling defects in her biliary tract. The size of the obstructing objects necessitated surgical retrieval of the stones. A histological assessment of the objects revealed fibrinoid materials with some cellular debris. Post-operative T-tube cholangiography (9 days after the operation) illustrated an open bile duct without any filling defects. Surprisingly, a relatively long choledochoduodenal fistula was detected. The fistula formation was assumed to have led to the development of the bile duct bezoar. CONCLUSION: Bezoar formation within the bile duct should be taken into consideration as a differential diagnosis, which can alter treatment modalities from surgery to less invasive methods such as more intra-ERCP efforts. Suspicions of the presence of bezoars are strengthened by the detection of a biliary enteric fistula through endoscopic retrograde cholangiopancreatography. Furthermore, patients at a higher risk of fistula formation should undergo a thorough ERCP in case there is a biliodigestive fistula having developed spontaneously
Extra-Intestinal Manifestations of Familial Adenomatous Polyposis
Familial adenomatous polyposis (FAP) is an autosomal dominantly inherited disorder, which results from a germ line mutation in the APC (adenomatous polyposis coli) gene. FAP is characterized by the formation of hundreds to thousands of colorectal adenomatous polyps. Although the development of colorectal cancer stands out as the most prevalent complication, FAP is a multisystem disorder of growth. This means, it is comparable to other diseases such as the MEN syndromes, Von Hippel-Lindau disease and neurofibromatosis. However, the incidence of many of its clinical features is much lower. Therefore, a specialized multidisciplinary approach to optimize health care—common for other disorders—is not usually taken for FAP patients. Thus, clinicians that care for and counsel members of high-risk families should have familiarity with all the extra-intestinal manifestations of this syndrome. FAP-related complications, for which medical attention is essential, are not rare and their estimated lifetime risk presumably exceeds 30%. Affected individuals can develop thyroid and pancreatic cancer, hepatoblastomas, CNS tumors (especially medulloblastomas), and various benign tumors such as adrenal adenomas, osteomas, desmoid tumors and dental abnormalities. Due to improved longevity, as a result of better prevention of colorectal cancer, the risk of these clinical problems will further increase
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