416 research outputs found

    El Futuro de la TecnologĂ­a CMOS

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    [spa] Desde su aparación en los años sesenta, la tecnología CMOS (del inglés Complementary Metal Oxide Semidanductor) ha ido evolucionando rápida- y constantemente llegando a ser la tecnología de fabricación de circuitos más utilizada en la actualidad. Sin embargo, la drástica reducción en tamaño de los transistores MOS convencionales supondrá, en los próximos años, cambios radicales en su estructura y por lo tanto en su proceso de fabricación. Así pues, el objetivo de este artículo será exponer en mayor o menor medida estos cambios así como dar una visión general de la tecnología CMOS dentro del marco de los circuitos integrados

    Diseño y fabricación de un filtro pasabanda pasivo con líneas acopladas

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    [spa] Las señales electromagnéticas que ocupan la banda de frecuencias de radio (RF) se transmiten por líneas de transmisión, que son estructuras materiales capaces de dirigir la energía de un punto a otro del circuito. Debido al campo electromagnético generado por una señal RF, dos líneas de transmisión próximas pueden propagar parte de la energía que circula de una a la otra. Aprovechando estas propiedades de acoplamiento capacitivo e inductivo entre líneas, se ha diseñado, simulado y fabricado un filtro pasabanda pasivo realizado con líneas de transmisión

    How to classify, diagnose, treat and follow-up extragonadal germ cell tumors? A systematic review of available evidence

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    Purpose To present the current evidence and the development of studies in recent years on the management of extragonadal germ cell tumors (EGCT). Methods A systematic literature search was conducted in Medline and the Cochrane Library. Studies within the search period (January 2010 to February 2021) that addressed the classifcation, diagnosis, prognosis, treatment, and follow-up of extragonadal tumors were included. Risk of bias was assessed and relevant data were extracted in evidence tables. Results The systematic search identifed nine studies. Germ cell tumors (GCT) arise predominantly from within the testis, but about 5% of the tumors are primarily located extragonadal. EGCT are localized primarily mediastinal or retroperitoneal in the midline of the body. EGCT patients are classifed according to the IGCCCG classifcation. Consecutively, all mediastinal non-seminomatous EGCT patients belong to the “poor prognosis” group. In contrast mediastinal seminoma and both retroperitoneal seminoma and non-seminoma patients seem to have a similar prognosis as patients with gonadal GCTs and metastasis at theses respective sites. The standard chemotherapy regimen for patients with a EGCT consists of 3–4 cycles (good vs intermediate prognosis) of bleomycin, etoposid, cisplatin (BEP); however, due to their very poor prognosis patients with non-seminomatous mediastinal GCT should receive a dose-intensifed or high-dose chemotherapy approach upfront on an individual basis and should thus be referred to expert centers Ifosfamide may be exchanged for bleomycin in cases of additional pulmonary metastasis due to subsequently planned resections. In general patients with non-seminomatous EGCT, residual tumor resection (RTR) should be performed after chemotherapy. Conclusion In general, non-seminomatous EGCT have a poorer prognosis compared to testicular GCT, while seminomatous EGGCT seem to have a similar prognosis to patients with metastatic testicular seminoma. The current insights on EGCT are limited, since all data are mainly based on case series and studies with small patient numbers and non-comparative studies. In general, systemic treatment should be performed like in testicular metastatic GCTs but upfront dose intensifcation of chemotherapy should be considered for mediastinal non-seminoma patients. Thus, EGCT should be referred to interdisciplinary centers with utmost experience in the treatment of germ cell tumors

    Can magnetic resonance imaging replace conventional computerized tomography for follow-up of patients with testicular cancer? A systematic review

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    Purpose Follow-up protocols for patients with testicular cancer (TC) have significantly reduced the number of cross-sectional imaging studies to reduce radiation exposure. At present, it is unclear whether magnetic resonance imaging (MRI) could replace conventional computerized tomography (CT) imaging. The objective of this study is to summarize the scientific evidence on this topic and to review guideline recommendations with regard to the use of MRI. Methods A systematic literature review was performed searching Medline and Cochrane databases for prospective studies on patients with TC in the follow-up care (last search in February 2021). Additionally, guideline recommendations for TC were screened. Data extraction and quality assessment of included studies were performed and used for a descriptive presentation of results. Results A total of four studies including two ongoing trials were identified. Overall, the scientific evidence of prospective comparative studies is based on 102 patients. Data suggest that abdominal imaging with MRI can replace conventional CT for detection of lymph node metastasis of the retroperitoneum to spare radiation exposure and contrast media application. However, experienced radiologists are needed. Clinical guidelines are aware of the risk of diagnosis-induced secondary malignancy due to CT imaging and some have adapted their recommendations accordingly. Results of the two ongoing trials on 738 patients are expected soon to provide more reliable results on this topic. Conclusions There is growing evidence that abdominopelvic MRI imaging can replace CT imaging during follow-up of patients with TC in order to reduce radiation exposure and diagnosis-induced secondary malignancy

    First-line salvage treatment options for germ cell tumor patients failing stage-adapted primary treatment : A comprehensive review compiled by the German Testicular Cancer Study Group

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    Purpose In this review, we summarize and discuss contemporary treatment standards and possible selection criteria for decision making after failure of adjuvant or first-line cisplatin-based chemotherapy for primarily localized or metastatic germ cell tumors. Methods This work is based on a systematic literature search conducted for the elaboration of the first German clinical practice guideline to identify prospective clinical trials and retrospective comparative studies published between Jan 2010 and Feb 2021. Study end points of interest were progression-free (PFS) and overall survival (OS), relapse rate (RR), and/or safety. Results Relapses of clinical stage I (CS I) patients irrespective of prior adjuvant treatment after orchiectomy are treated stage adapted in accordance for primary metastatic patients. Surgical approaches for sole retroperitoneal relapses are investigated in ongoing clinical trials. The appropriate salvage chemotherapy for metastatic patients progressing or relapsing after first-line cisplatin-based chemotherapy is still a matter of controversy. Conventional cisplatin-based chemotherapy is the international guideline-endorsed standard of care, but based on retrospective data high-dose chemotherapy and subsequent autologous stem cell transplantation may offer a 10–15% survival benefit for all patients. Secondary complete surgical resection of all visible residual masses irrespective of size is paramount for treatment success. Conclusions Patients relapsing after definite treatment of locoregional disease are to be treated by stage-adapted first-line standard therapy for metastatic disease. Patients with primary advanced/metastatic disease failing one line of cisplatin-based combination chemotherapy should be referred to GCT expert centers. Dose intensity is a matter of ongoing debate, but sequential high-dose chemotherapy seems to improve patients’ survival

    Dispersal within a spatially structured population of lesser kestrels: The role of spatial isolation and conspecific attraction

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    1. Factors governing dispersal rates have seldom been examined in spatially structured populations of vertebrates. We gathered information during 8 years on transfer rates between subpopulations in a spatially structured, growing population of colonial lesser kestrels Falco naumanni, and analysed the contribution of several variables related to spatial isolation and characteristics of both subpopulation of origin and destination on probabilities of dispersal. 2. Lesser kestrels were highly philopatric to their subpopulations, but first-breeders dispersed more often than adults (26% vs. 4%, n = 1706) because adults were reluctant to move from familiar areas. Frequency of subpopulation change was higher in females than in males (first-recruiters: 30% vs. 22%, n = 987; adults 5% vs. 1%, n = 719), according to their different breeding roles. However, all populational factors had an equal effect on individuals of different sex and dispersal status. 3. Movement rates decreased with inter-subpopulation distance - indicating that travelling to distant subpopulations may impose costs in terms of breeding prospects -and with the number of subpopulations, which increased during our study period. 4. Conspecific attraction strongly influenced the probability of dispersal: it was relatively higher in largely populated subpopulations, and individuals of large subpopulations were reluctant to change to others. These results were neither influenced by the size and breeding density of the subpopulations nor by habitat quality in terms of food availability or risk of predation, as indicated by breeding success of kestrels at each subpopulation. The number of conspecifics could be used by the kestrels as a cue of patch quality in terms of settlement options, and large subpopulations could be more easily detected by prospecting birds. 5. Our study highlights the fact that several assumptions of theoretical metapopulation modelling are often not fulfilled in nature. Both theoretical models and management strategies on spatially structured populations or metapopulations should thus consider the number, population size, and spatial distribution of local populations, as well as their relationships with the dispersal ability of the species.Peer Reviewe

    Impact of Low-Dose Dronabinol Therapy on Cognitive Function in Cancer Patients Receiving Palliative Care: A Case-Series Intervention Study

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    BACKGROUND: Cannabis may offer therapeutic benefits to patients with advanced cancer not responding adequately to conventional palliative treatment. However, tolerability is a major concern. Cognitive function is a potential adverse reaction to tetrahydrocannabinol containing regimens. The aim of this study was to test cognitive function in patients being prescribed dronabinol as an adjuvant palliative therapy.METHODS: Adult patients with advanced cancer and severe related pain refractory to conventional palliative treatment were included in this case-series study. Patients were examined at baseline in conjunction with initiation of dronabinol therapy and at a two-week follow-up using three selected Wechsler's adult intelligence scale III neurocognitive tests: Processing Speed Index (PSI), Perceptual Organization Index (POI), and Working Memory Index (WMI). Patients were also assessed using pain visual analog scale, Major Depression Inventory, and Brief Fatigue Inventory.RESULTS: Eight patients consented to take part in the study. Two patients discontinued dronabinol therapy, one due to a complaint of dizziness and another critical progression of cancer disease, respectively. The remaining six patients were successfully treated with a daily dosage of 12.5 mg dronabinol (p = 0.039). PSI (p = 0.020), POI (p = 0.034.), and WMI (p = 0.039).CONCLUSIONS: Cognitive function improved in this group of patients with advanced cancer in conjunction with low-dose dronabinol therapy. The cause is likely multifactorial including reported relief of cancer-associated symptoms. Further clinical investigation is required.</p

    Experimental Determination of the Uncertainty of the Absorption Coefficient of Crystalline Silicon

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    Based on a combined analysis of spectroscopic ellipsometry, reflectance and transmittance measurements as well as spectrally resolved luminescence measurements and spectral responsivity measurements, we present data of the coefficient of band-to-band absorption of crystalline silicon at 295 K in the wavelength range 250 - 1450 nm. A systematic measurement uncertainty analysis according to the "Guide to the Expression of Uncertainty in Measurements" (GUM) is carried out for each method, showing that the relative uncertainty of the absorption coefficient data so determined is of the order of 0.3% at 300 nm, 1% at 900 nm, 10% at 1200 nm and 180% at 1450 nm. The data are consolidated by comparison of measurements carried out independently at different institutions. The uncertainty of solar cell energy conversion predictions by means of simulations due to the uncertainty of the absorption coefficient data is shown to be of the order of 0.1% relative.Deutsche Bundesstiftung UmweltState of Lower Saxon
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