137 research outputs found

    Positioning with GNSS and 5G: Analysis of Geometric Accuracy in Urban Scenarios

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    GNSS positioning in urban scenarios suffers for the scarce visibility of satellites. Integration with 5G services for positioning could improve this situation. In this paper, the digital surface models (DSMs) relevant to different urban scenarios, namely residential streets and urban canyons, are simulated around one observer in northern Italy (Milano) for one day of the year chosen as an example. The time series of the number of in-view GNSS satellites, their geometry and the derived quality indexes (position dilution of precision (PDOP)) are computed and analyzed. As expected, in urban canyons, a significant number of epochs does not provide four satellites within view, and many more epochs present really mediocre PDOPs. In residential streets, the situation is always quite fair. Different geometric configurations of 5G base stations are simulated around the observer. The availability of 5G times of arrival (ToAs) and their differences (TDoAs) is hypothesized, and the integration of these observations with GNSS pseudoranges is analyzed, again in terms of the PDOPs. In residential streets, 5G availability improves the positioning. In urban canyons, the optimal configuration of 5G base stations (five base stations around the observer) completely solves the positioning problem for all the epochs of the day. Less favorable configurations (four and three base stations) improve epochs with poor PDOPs in a GNSS-only configuration. They allow the positioning of epochs with few satellites but cannot completely replace the GNSS

    Nonlinear Multi-Frequency Converter Array for Vibration Energy Harvesting in Autonomous Sensors☆

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    Abstract This work proposes and experimentally validates a vibration energy harvester which combines the multi-frequency and nonlinear approaches into a converter array. The converter array consists of four piezoelectric cantilevers composed of ferromagnetic substrates with screen-printed lead zirconate titanate (PZT) layers coupled with a single permanent magnet elastically suspended on the array base in order to create a nonlinear behaviour. The presence of a moving magnet and the possibility to realize cantilevers with different potential curves can be useful to obtain a collective nonlinear behaviour due to strong coupling irrespective of the amplitude of the mechanical excitation, therefore increasing the overall effectiveness of the converter array. The experimental results confirm that combining cantilevers with different potential curves can be useful to obtain a collective bistable behaviour, therefore increasing the overall effectiveness of the converter array

    Ectopic expression of inactive forms of yeast DNA topoisomerase II confers resistance to the anti-tumour drug, etoposide.

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    Drug resistance to anti-tumour agents often coincides with mutations in the gene encoding DNA topoisomerase II alpha. To examine how inactive forms of topoisomerase II can influence resistance to the chemotherapeutic agent VP-16 (etoposide) in the presence of a wild-type allele, we have expressed point mutations and carboxy-terminal truncations of yeast topoisomerase II from a plasmid in budding yeast. Truncations that terminate the coding region of topoisomerase II at amino acid (aa) 750, aa 951 and aa 1044 are localised to both the cytosol and the nucleus and fail to complement a temperature-sensitive top2-1 allele at non-permissive temperature. In contrast, the plasmid-borne wild-type TOP2 allele and a truncation at aa 1236 are nuclear localised and complement the top2-1 mutation. At low levels of expression, truncated forms of topoisomerase II render yeast resistant to levels of etoposide 2- and 3-fold above that tolerated by cells expressing the full-length enzyme. Maximal resistance is conferred by the full-length enzyme carrying a mutated active site (Y783F) or a truncation at aa 1044. The level of phosphorylation of topoisomerase II was previously shown to correlate with drug resistance in cultured cells, hence we tested mutants in the major casein kinase II acceptor sites in the C-terminal domain of yeast topoisomerase II for changes in drug sensitivity. Neither ectopic expression of the C-terminal domain alone nor phosphoacceptor site mutants significantly alter the host cell's sensitivity to etoposide

    From ESR to continuous CC-ESRR process: development in remelting technology towards better products and productivity

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    This work describes the development of the Electro Slag Remelting process at Valbruna, starting in the 1997 with an innovative INTECO ESR plant equipped with protective gas hood (for inert atmosphere remelting), electrode change system and fully computer controlled. The second step was made a couple of years later when the plant was upgraded to ESRR® (Electro Slag Rapid Remelting). With this new feature Acciaierie Valbruna was able to obtain ready to roll remelted billets (145, 160 and 200 mm square), getting rid of the traditional forging or blooming operations needed in case of traditional ESR ingot remelting. This was surely a dramatic cut off in product cost accounting and production lead time without loosing any of the special characteristics typical of ESR products. Unfortunately the ESRR® process, very promising in terms of cycle complexity reduction and quality of the product, because of its “batch-type” operation, was uneconomical in regard of productivity of the plant and not feasible in industrial scale. The final step of this development was made at the beginning of 2002 when t he ESRR® plant was upgraded again and equipped with an innovative INTECO automatic manipulator, which resulted in a continuous process. This was the birth of the very first CC-ESRR® (continuous casting electro slag rapid remelting) plant in the world. The first part of this paper focuses o n the development of processes and equipment, giving a brief description of ESR, ESRR® and CC-ESRR® process while the second part describes the results of a series of test remelting used for product and CC-ESRR® process characterization

    Late-onset Parkinsonism in NFκB/c-Rel-deficient mice.

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    Activation of the nuclear factor \u3baB/c-Rel can increase neuronal resilience to pathological noxae by regulating the expression of pro-survival manganese superoxide dismutase (MnSOD, now known as SOD2) and Bcl-xL genes. We show here that c-Rel-deficient (c-rel(-/-)) mice developed a Parkinson's disease-like neuropathology with ageing. At 18 months of age, c-rel(-/-) mice exhibited a significant loss of dopaminergic neurons in the substantia nigra pars compacta, as assessed by tyrosine hydroxylase-immunoreactivity and Nissl staining. Nigral degeneration was accompanied by a significant loss of dopaminergic terminals and a significant reduction of dopamine and homovanillic acid levels in the striatum. Mice deficient of the c-Rel factor exhibited a marked immunoreactivity for fibrillary \u3b1-synuclein in the substantia nigra pars compacta as well as increased expression of divalent metal transporter 1 (DMT1) and iron staining in both the substantia nigra pars compacta and striatum. Aged c-rel(-/-) mouse brain were characterized by increased microglial reactivity in the basal ganglia, but no astrocytic reaction. In addition, c-rel(-/-) mice showed age-dependent deficits in locomotor and total activity and various gait-related deficits during a catwalk analysis that were reminiscent of bradykinesia and muscle rigidity. Both locomotor and gait-related deficits recovered in c-rel(-/-) mice treated with l-3,4-dihydroxyphenylalanine. These data suggest that c-Rel may act as a regulator of the substantia nigra pars compacta resilience to ageing and that aged c-rel(-/-) mice may be a suitable model of Parkinson's disease

    Late-onset Parkinsonism in NFκB/c-Rel-deficient mice

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    Activation of the nuclear factor κB/c-Rel can increase neuronal resilience to pathological noxae by regulating the expression of pro-survival manganese superoxide dismutase (MnSOD, now known as SOD2) and Bcl-xL genes. We show here that c-Rel-deficient (c-rel(-/-)) mice developed a Parkinson's disease-like neuropathology with ageing. At 18 months of age, c-rel(-/-) mice exhibited a significant loss of dopaminergic neurons in the substantia nigra pars compacta, as assessed by tyrosine hydroxylase-immunoreactivity and Nissl staining. Nigral degeneration was accompanied by a significant loss of dopaminergic terminals and a significant reduction of dopamine and homovanillic acid levels in the striatum. Mice deficient of the c-Rel factor exhibited a marked immunoreactivity for fibrillary α-synuclein in the substantia nigra pars compacta as well as increased expression of divalent metal transporter 1 (DMT1) and iron staining in both the substantia nigra pars compacta and striatum. Aged c-rel(-/-) mouse brain were characterized by increased microglial reactivity in the basal ganglia, but no astrocytic reaction. In addition, c-rel(-/-) mice showed age-dependent deficits in locomotor and total activity and various gait-related deficits during a catwalk analysis that were reminiscent of bradykinesia and muscle rigidity. Both locomotor and gait-related deficits recovered in c-rel(-/-) mice treated with l-3,4-dihydroxyphenylalanine. These data suggest that c-Rel may act as a regulator of the substantia nigra pars compacta resilience to ageing and that aged c-rel(-/-) mice may be a suitable model of Parkinson's disease

    Malignant melanoma of the stomach presenting in a woman: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Malignant melanoma is reported to metastasize to all organs of the human body. Although it is common for it to metastasize to the gastrointestinal tract, a melanoma located primarily in the gastric mucosa is an uncommon tumor. Gastrointestinal metastases are rarely diagnosed before death with radiological and endoscopic techniques.</p> <p>Case presentation</p> <p>In this case report the clinical course and treatment of a woman with melanoma of the stomach, without any other detectable primary lesion, is presented and discussed. A 55-year-old Turkish woman presented to our clinic with complaints of muscle pain and bone pain in the left side of her chest. During an upper gastrointestinal system endoscopy, dark cherry-colored, light elevated, round-shaped lesions were taken from her gastric fundus and from the first part of her duodenum. Biopsies from these samples were determined to be malignant melanoma by the pathologist.</p> <p>Conclusion</p> <p>Metastatic malignant melanoma cases should be examined through endoscopy for gastrointestinal metastases.</p
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