Position reporting system using small satellites

A system able to provide position reporting and monitoring services for mobile applications represents a natural complement to the Global Positioning System (GPS) navigation system. The system architecture is defined on the basis of the communications requirements derived by user needs, allowing maximum flexibility in the use of channel capacity, and a very simple and low cost terminal. The payload is sketched, outlining the block modularity and the use of qualified hardware. The global system capacity is also derived. The spacecraft characteristics are defined on the basis of the payload requirements. A small bus optimized for Ariane IV, Delta II vehicles and based on the modularity concept is presented. The design takes full advantage of each launcher with a common basic bus or bus elements for a mass production

Endoscopic-assisted removal of ventricular catheter in high-risk patients

Introduction. Ventriculoperitoneal shunt carries a non-negligible failure rate often requiring multiple surgical procedures during patient’s lifetime. The most common cause is obstruction of the ventricular catheter that can be embedded in adhesions with choroid plexus, ependymal tissue, and fibrous material. In such cases, or when an intraventricular tumor is present, particular attention must be paid when removal of the ventricular catheter is required. The potential adhesions with the tip of the ventricular catheter results in an increased risk of life-threatening hemorrhage. Materials and methods. We present the case of a ventriculoperitoneal shunt proximal revision in a von Hippel–Lindau affected patient. The neuroendoscopic exploration to restore the patency of the ventricular system made it possible to notice a fibrous adhesion between the tip of the catheter and a pituitary hemangioblastoma abutting into the third ventricle. Discussion. Pituitary stalk hemangioblastoma is an infrequent localization, although it represents the most common supratentorial site of hemangioblastoma in patients affected by von Hippel–Lindau syndrome. In this and in similar cases, endoscopic-assisted shunt revision allows visualizing the tip of the ventricular catheter and eventual adhesions that can be coagulated and cut by simple maneuvers, without any morbidity for patients. Conclusion. In a ventriculoperitoneal shunt revision with the concomitant presence of an intraventricular tumor or lesion at risk of bleeding, the surgical procedure should be performed under neuroendoscopic observation to reduce the risk of intraventricular hemorrhage

Cavernous Angioma of the Corpus Callosum Presenting with Acute Psychosis

Psychiatric symptoms may occasionally be related to anatomic alterations of brain structures. Particularly, corpus callosum lesions seem to play a role in the change of patients’ behavior. We present a case of a sudden psychotic attack presumably due to a hemorrhagic cavernous angioma of the corpus callosum, which was surgically removed with complete resolution of symptoms. Although a developmental defect like agenesis or lipoma is present in the majority of these cases, a growing lesion of the corpus callosum can rarely be the primary cause. Since it is potentially possible to cure these patients, clinicians should be aware of this association

High frequency electro-optic measurement of strained silicon racetrack resonators

The observation of the electro-optic effect in strained silicon waveguides has been considered as a direct manifestation of an induced $\chi^{(2)}$ non-linearity in the material. In this work, we perform high frequency measurements on strained silicon racetrack resonators. Strain is controlled by a mechanical deformation of the waveguide. It is shown that any optical modulation vanishes independently of the applied strain when the applied voltage varies much faster than the carrier effective lifetime, and that the DC modulation is also largely independent of the applied strain. This demonstrates that plasma carrier dispersion is responsible for the observed electro-optic effect. After normalizing out free carrier effects, our results set an upper limit of $8\,pm/V$ to the induced high-speed $\chi^{(2)}_{eff,zzz}$ tensor element at an applied stress of $-0.5\,GPa$. This upper limit is about one order of magnitude lower than the previously reported values for static electro-optic measurements

Posterior wiring with sublaminar polyester bands, titanium-peek fixation system for C2 fracture management: a 4-patient case series with a maximum of 18 months’ follow-up

Background: C2 fractures can be classified differently when dens, pedicles or body are injured. With regards to the best management of Type-II Anderson-D’Alonzo fractures, Hangman’s fractures of pedicles and C2 body fractures are more debatable. However, vertebral pedicle and/or articular screw and dorsal wiring are the most common surgical posterior approaches opted for. Compared to the screw technique, dorsal wiring provides certain benefits such as a lower risk of vertebral artery injury, no need for navigation, less lateral dissection of the paraspinal muscles, shorter surgery time and lower medical costs. Case Description: Two patients with failed conservative treatment for Anderson-D’Alonzo Type-III fractures (Cases 1A and 1B), a patient suffering from a Type-II Hangman’s fracture (Case 2) and a patient with failed conservative treatment for a C2 transversal body fracture (Case 3) underwent surgery at the Neurosurgery Division of the University Hospital of Modena (Italy) between July 2020 and September 2021. All patients were treated with posterior wiring with 5 mm Polyester bands, titanium-peek fixation system (Jazz-Lock system MediNext®-Implanet) inserted through the C1 posterior arch and either the C2 or C3 laminae. A fracture diastasis reduction was observed ranging between 4.5 and 1 mm. No intraoperative and post-operative complications were encountered. The duration of the period of hospitalisation ranged between 5 and 12 days. All patients who had worked prior to the traumatic event were able to return to work 18 months following surgery. Conclusions: In reducing C2 fractures, a sublaminar fixation with polyester bands and a titanium-peek fixation system can be proposed for fragile and elderly patients

ChIP-Seq data analysis to define transcriptional regulatory networks

The first step in the definition of transcriptional regulatory networks is to establish correct relationships between transcription factors (TFs) and their target genes, together with the effect of their regulatory activity (activator or repressor). Fundamental advances in this direction have been made possible by the introduction of experimental techniques such as Chromatin Immunoprecipitation, which, coupled with next-generation sequencing technologies (ChIP-Seq), permit the genome-wide identification of TF binding sites. This chapter provides a survey on how data of this kind are to be processed and integrated with expression and other types of data to infer transcriptional regulatory rules and codes

Power efficiency estimation of silicon nanocrystals based light emitting devices in alternating current regime

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Comparisons RANS and URANS numerical results with experiments in a vaned diffuser of a centrifugal pump

the paper presents the analysis of the performance and the internal flow behaviour in the vaned diffuser of a radial flow pump using PIV (particles image velocimetry) technique, pressure probe traverses and numerical simula\u2011 tions. PIV measurements have been performed at different hub to shroud planes inside one diffuser channel passage for a given rotational speed and various flow rates. For each operating condition, PIV measurements have been made for differ\u2011 ent angular positions of the impeller. Probe traverses have also been performed using a 3 holes pressure probe from hub to shroud diffuser width at different radial locations in between the two diffuser geometrical throats. the numerical simulations were realized with the two commercial codes: i\u2011Star CCM+ 8.02.011 (rAnS (reynolds Averaged navier Stokes) turbu\u2011 lence model, frozen rotor and unsteady calculations), ii\u2011CFX 10.0 (turbulence modelled with DeS model (Detached eddy Simulation) combining rAnS with leS (large eddy Simulation), unsteady calculations). Comparisons between numerical (fully unsteady calculations) and experimental results are presented and discussed for two flow rates. In this respect, the effects of fluid leakage due to the gap between the rotating and fixed part of the pump model are analysed and discussed