131 research outputs found

    Optimization of Total Variation regularization to improve the accuracy of the characterization of vertical cracks by lock-in vibrothermography

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    We use lock-in vibrothermography to characterize vertical cracks. In the presence of ultrasounds, the rubbing of the crack faces produces heat which induces a temperature rise at the surface that is measured with an infrared camera. We fit data obtained by modulating the amplitude of the ultrasounds at several modulation frequencies. The inverse problem consisting of finding the geometry and location of the heat source from vibrothermography data is ill-posed, which makes it necessary to stabilize the inversion algorithm. We analyze the effect of the stabilizing term on the accuracy of the reconstructions

    Fast geometrical characterization of vertical cracks using burst vibrothermography

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    Burst vibrothermography is used to characterize vertical cracks. We excite the sample with a short ultrasound burst of constant intensity and we register the evolution of the surface temperature during and after the burst. Among all this information, we characterize the crack using the thermogram obtained and the end of the burst and the evolution of the temperature (timing graph) at the center of the thermograms. We have developed a stabilized inversion algorithm to retrieve the area and depth of the crack. Inversions of experimental data obtained with samples containing calibrated heat sources confirm the validity of the method

    Vertical Cracks Excited in Lock-in Vibrothermography Experiments: Identification of Open and Inhomogeneous Heat Fluxes

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    Lock-in vibrothermography has proven to be very useful to characterizing kissing cracks producing ideal, homogeneous, and compact heat sources. Here, we approach real situations by addressing the characterization of non-compact (strip-shaped) heat sources produced by open cracks and inhomogeneous fluxes. We propose combining lock-in vibrothermography data at several modulation frequencies in order to gather penetration and precision data. The approach consists in inverting surface temperature amplitude and phase data by means of a least-squares minimization algorithm without previous knowledge of the geometry of the heat source, only assuming knowledge of the vertical plane where it is confined. We propose a methodology to solve this illposed inverse problem by including in the objective function penalty terms based on the expected properties of the solution. These terms are described in a comprehensive and intuitive manner. Inversions of synthetic data show that the geometry of non-compact heat sources is identified correctly and that the contours are rounded due to the penalization. Inhomogeneous smoothly varying fluxes are also qualitatively retrieved, but steep variations of the flux are hard to recover. These findings are confirmed by inversions of experimental data taken on calibrated samples. The proposed methodology is capable of identifying heat sources generated in lock-in vibrothermography experiments. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

    Analysis of the Antimicrobial Resistance Profile of Microorganisms Closely Related to Healthcare-Associated Infections: Catalonia, 2016-2019

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    Resistència als antimicrobians; Infeccions; Assistència sanitàriaResistencia a los antimicrobianos; Infecciones; Asistencia sanitariaResistance to antimicrobials; Infections; Health careL’objectiu d’aquest Informe és l’anàlisi de la sensibilitat antimicrobiana dels microorganismes estretament associats a les IRA. També s’analitzen els seus mecanismes de resistència i la presència de soques multiresistents, extremadament resistents i panresistents en els anys 2016 - 2019. Els microorganismes objecte d’estudi són cocs grampositius: Enterococcus faecalis, Enterococcus faecium, Streptococcus agalactiae, Streptococcus pyogenes i Staphylococus aureus (MSSA i MRSA); els enterobacteris: Escherichia coli i Klebsiella pneumoniae, i els bacils gramnegatius no fermentadors: Acinetobacter baumannii i Pseudomonas aeruginosa

    PLA2 G4E, a candidate gene for resilience in Alzheimer's disease and a new target for dementia treatment

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    Clinical studies revealed that some aged-individuals accumulate a significant number of histopathological Alzheimer´s disease (AD) lesions in their brain, yet without developing any signs of dementia. Animal models of AD represent suitable tools to identify genes that might promote cognitive resilience and hence, this study first set out to identify cognitively resilient individuals in the aged-Tg2576 mouse model. A transcriptomic analysis of these mice identified PLA2 G4E as a gene that might confer resistance to dementia. Indeed, a significant decrease in PLA2 G4E is evident in the brain of late-stage AD patients, whereas no such changes are observed in early stage patients with AD neuropathological lesions but no signs of dementia. We demonstrated that adeno-associated viral vector-mediated overexpression of PLA2 G4E in hippocampal neurons completely restored cognitive deficits in elderly APP/PS1 mice, without affecting the amyloid or tau pathology. These PLA2 G4E overexpressing APP/PS1 mice developed significantly more dendritic spines than sham-injected mice, coinciding with the cognitive improvement observed. Hence, these results support the idea that a loss of PLA2 G4E might play a key role in the onset of dementia in AD, highlighting the potential of PLA2 G4E overexpression as a novel therapeutic strategy to manage AD and other disorders that course with memory deficits

    Anti-Stokes laser cooling in bulk Erbium-doped materials

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    We report the first observation of anti-Stokes laser-induced cooling in the Er^{3+}:KPb_{2}Cl_{5} crystal and in the Er^{3+}:CNBZn (CdF_{2}-CdCl_{2}-NaF-BaF_{2}-BaCl_{2}-ZnF_{2}) glass. The internal cooling efficiencies have been calculated by using photothermal deflection spectroscopy. Thermal scans acquired with an infrared thermal camera proved the bulk cooling capability of the studied samples. Implications of these results are discussed.Comment: 4 pages, 4 figures. The figures enclosed with this submission are low quality ones. Versions of this paper with high quality figures are available upon reques

    ESTRO/ACROP IORT recommendations for intraoperative radiation therapy in primary locally advanced rectal cancer

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    Summary: Carcinoma of the rectum is a heterogeneous disease. The clinical spectrum identifies a subset of patients with locally advanced tumours that are close to or involve adjoining structures, such as the sacrum, pelvic sidewalls, prostate or bladder. Within this group of patients categorized as ‘‘locally advanced”, there is also variability in the extent of disease with no uniform definition of resectability. A practice-oriented definition of a locally advanced tumour is a tumour that cannot be resected without leaving microscopic or gross residual disease at the resection site. Since these patients do poorly with surgery alone, irradiation and chemotherapy have been added to improve the outcome. Intraoperative irradiation (IORT) is a component of local treatment intensification with favourable results in this subgroup of patients. International guidelines (National Comprehensive Cancer Network (NCCN) guidelines) currently recommend the use of IORT for rectal cancer resectable with very close or positive margins, especially for T4 and recurrent cancers. We report the ESTRO-ACROP (European Society for Radiotherapy and Oncology - Advisory Committee on Radiation Oncology Practice) recommendations for performing IORT in primary locally advanced rectal cancer

    Update on the Serum Biomarkers and Genetic Factors Associated with Safety and Efficacy of rt-PA Treatment in Acute Stroke Patients

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    An accurate understanding of the mechanisms underlying an individual's response to rt-PA treatment is critical to improve stroke patients' management. We thus reviewed the literature in order to identify biochemical and genetic factors that have been associated with safety and efficacy of rt-PA administration after stroke

    Intraoperative radiotherapy electron boost followed by moderate doses of external beam radiotherapy in resected soft-tissue sarcoma of the extremities

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    To analyze the patterns of failure and the toxicity profile of intraoperative electron beam radiotherapy (IOERT) after resection of soft tissue sarcomas of the extremities (STS). PATIENTS AND METHODS: Forty-five patients with extremity STS were treated with IOERT and moderate-dose postoperative radiotherapy (45-50 Gy). Twenty-six patients were treated for primary disease (PD) and 19 patients for an isolated recurrence (ILR). Tumor size was >5 cm (maximum diameter) in 36 patients (80%), and high-grade histology in PD patients was present in 14 patients (54%). In nine patients, IOERT was used alone, due to previous irradiation or patient refusal. Chemotherapy (neoadjuvant and/or adjuvant) was mainly given to high-grade tumors. RESULTS: Nine patients relapsed in the extremity (20%), and 12 patients in distant sites (28%). Actuarial local control at 5 years was 88% for patients with negative/close margins and 57% for patients presenting positive margins (P=0.04). Five patients (11%) developed neuropathy associated with the treatment. Extremity preservation was achieved in 40 patients (88%). With a median follow-up of 93 months (range: 27-143 months) for the patients at risk, 25 patients remain alive (a 7-year actuarial survival rate of 75% for PD and 47% for ILR; P=0.01). CONCLUSIONS: IOERT combined with moderate doses of external beam irradiation yields high local control and extremity preservation rates in resected extremity STS. Peripheral nerves in the IOERT field are dose-limiting structures requiring a dose compromise in the IOERT component to avoid severe neurological damage

    Anàlisi de la sensibilitat als antimicrobians d’Enterococcus faecalis i Enterococcus faecium: Catalunya, 2016-2022

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    Resistència als antimicrobians; Infeccions; EnterococcusResistencia a los antimicrobianos; Infecciones; EnterococcusResistance to antimicrobials; Infections; EnterococcusL’objectiu d’aquest Informe és l’anàlisi de la sensibilitat als antibiòtics i dels mecanismes de resistència d’E. faecalis i E. faecium invasius aïllats a Catalunya en el període 2016-2022
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