215 research outputs found

    Experimental Characterization of Two-Phase Flow Instability Thresholds in Helically Coiled Parallel Channels

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    Among the various types of instabilities affecting vapor generation in boiling systems, Density Wave Oscillation (DWO) occurrence within parallel channels is depicted. Parallel channel instability may represent a critical concern for the operation and safety of the once-through steam generators adopted in GenIII+ and GenIV nuclear reactor concepts. Extensive attention is required to determine the safe operating regime of a two-phase heat exchanger, by evaluating the instability threshold values of system parameters such as thermal power, flow rate, pressure, inlet temperature and exit quality. While the amount of published experimental work in the field of DWOs investigation in parallel straight tubes is overwhelming since the ’60, scarce attempt has been dedicated to the helical-coiled tube geometry. Conversely, coiled pipes are foreseen for applications to steam generators of the next generation NPPs, due to compactness and higher efficiency in heat transfer. The paper deals with the results of an experimental campaign on flow instability occurrence in two electrically heated helically coiled parallel tubes. In the framework of the IRIS project, a full-scale open-loop experimental facility simulating the thermal-hydraulic behavior of a helically coiled steam generator has been built and operated at SIET labs in Piacenza (Italy). The facility comprises two helical tubes (1 m coil diameter, 32 m length, 8 m height), connected via lower and upper headers. In order to excite flow unstable conditions starting from stable operating conditions, supplied electrical power was gradually increased up to the appearance of permanent and regular flow oscillations. Several flow instability threshold conditions were identified, in a test matrix of pressures (80 bar, 40 bar, 20 bar), mass fluxes (600 kg/m2s, 400 kg/m2s, 200 kg/m2s), and inlet subcooling (from -30% up to ~0). The long test section feature and the helical-coiled tube geometry render the present facility a quite unique test case in the outline of two-phase flow instability experimental studies. Parametric effects of the operating pressure, flow rate and inlet subcooling on the threshold power are discussed. The period of oscillations is also discussed

    Wide spetcrum mutational analysis of metastatic renal cell cancer : a retrospective next generation sequencing approach

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    Renal cell cancer (RCC) is characterized by histological and molecular heterogeneity that may account for variable response to targeted therapies. We evaluated retrospectively with a next generation sequencing (NGS) approach using a pre-designed cancer panel the mutation burden of 32 lesions from 22 metastatic RCC patients treated with at least one tyrosine kinase or mTOR inhibitor. We identified mutations in the VHL, PTEN, JAK3, MET, ERBB4, APC, CDKN2A, FGFR3, EGFR, RB1, TP53 genes. Somatic alterations were correlated with response to therapy. Most mutations hit VHL1 (31,8%) followed by PTEN (13,6%), JAK3, FGFR and TP53 (9% each). Eight (36%) patients were wild-type at least for the genes included in the panel. A genotype concordance between primary RCC and its secondary lesion was found in 3/6 cases. Patients were treated with Sorafenib, Sunitinib and Temsirolimus with partial responses in 4 (18,2%) and disease stabilization in 7 (31,8%). Among the 4 partial responders, 1 (25%) was wild-type and 3 (75%) harbored different VHL1 variants. Among the 7 patients with disease stabilization 2 (29%) were wild-type, 2 (29%) PTEN mutated, and single patients (14% each) displayed mutations in VHL1, JAK3 and APC/CDKN2A. Among the 11 non-responders 7 (64%) were wild-type, 2 (18%) were p53 mutated and 2 (18%) VHL1 mutated. No significant associations were found among RCC histotype, mutation variants and response to therapies. In the absence of predictive biomarkers for metastatic RCC treatment, a NGS approach may address single patients to basket clinical trials according to actionable molecular specific alterations.Peer reviewe

    Early primary tumor response in metastatic RCC patients treated with immune checkpoint inhibitors-based combinations

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    Background: 25-30% of renal cell carcinoma presents with metastases (mRCC) at diagnosis. The activity of immune checkpoint inhibitor (ICI)-combinations on the primary tumor (PT) is debated. Patients andMethods: mRCC patients (pts) with PT who received first-line nivolumab plus ipilimumab (N/I) or pembrolizumab plus axitinib (P/A) were included. We investigated the early primary tumor response (EPTR) at the first radiological assessment. Results: 73 pts were included. The median early reduction of the PT longest diameter was 12.4% with P/A versus 6.2% with N/I (p = 0.42). We evaluated if the type of EPTR could affect the metastases response. Among pts with PT stable disease (SD), 8.3% had metastatic disease progression (PD) with P/A and 34.8% with N/I. Early PT partial response (PR) was associated with no metastatic PD with both N/I and P/A. The 2 pts with PT PD had also metastatic PD to P/A. Of the 3 PT with PD to N/I, 1 had metastatic SD and 2 PD. In the overall population, of the 94.1% without PT progression (PR+SD), 47.5% had metastatic PR, 35.6% SD, 16.9% PD. Conclusions: ICIs-combinations achieved an early PT PR in about 10-20%, without any complete responses. Only a small percentage of PT had an early PD, mainly associated with metastatic PD. However, among those PT without an early progression, metastatic PR can be achieved in approximately 50% of cases

    The Cardiovascular Toxicity of Abiraterone and Enzalutamide in Prostate Cancer

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    We analyzed the cardiovascular toxicities related to the use of abiraterone and enzalutamide in prostate cancer. We found that these agents are associated with an increased risk of all- and high-grade cardiac toxicity as well as an increased risk of all- and high-grade hypertension. Follow-up for the onset of treatment-related cardiovascular events should be considered in these patients treated with abiraterone and enzalutamide.Introduction: The cardiovascular toxicity related to abiraterone and enzalutamide has been previously studied by our group. In this analysis, we aim to update our previous findings related to abiraterone and enzalutamide, including the new available evidence, both in castration-resistant and hormone-sensitive prostate cancer. Patients and Methods: Prospective studies were identified by searching the MEDLINE/PubMed, Cochrane Library, and ASCO Meeting abstracts. Combined relative risks (RRs) and 95% confidence intervals (Cis) were calculated using fixed- or random-effects methods. Results: We included 7 articles in this meta-analysis, covering a total of 8660 patients who were used to evaluate cardiovascular toxicity. The use of new hormonal agents was associated with an increased risk of all-grade (RR, 1.36; 95% CI, 1.13-1.64; P = .001) and high-grade (RR, 1.84; 95% CI, 1.21-2.80; P = .004) cardiac toxicity. The use of new hormonal agents was also associated with an increased risk of all-grade (RR, 1.98; 95% CI, 1.62-2.43; P = .001) and high-grade (RR, 2.26; 95% CI, 1.84-2.77; P = .004) hypertension compared with the controls. Abiraterone was found to significantly increase the risk of both cardiac toxicity and hypertension, whereas enzalutamide significantly increases only the risk of hypertension. No differences were found based on the dose of prednisone used with abiraterone. The major limitation of this study is that data are available only as aggregate, and no single-patient information could be analyzed. Conclusions: Abiraterone and enzalutamide significantly increase the incidence and RR of cardiovascular toxicity in patients affected by metastatic prostate cancer. Follow-up for the onset of treatment-related cardiovascular events should therefore be considered in these patients. (C) 2017 Elsevier Inc. All rights reserved

    Molecular analysis of a male breast cancer patient with prolonged stable disease under mTOR/PI3K inhibitors BEZ235/everolimus

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    The mTORC1 inhibitor everolimus (Afinitor/RAD001) has been approved for multiple cancer indications, including ER(+)/HER2(-) metastatic breast cancer. However, the combination of everolimus with the dual PI3K/mTOR inhibitor BEZ235 was shown to be more efficacious than either everolimus or BEZ235 alone in preclinical models. Herein, we describe a male breast cancer (MBC) patient who was diagnosed with hormone receptor-positive (HR(+))/HER2(-) stage IIIA invasive ductal carcinoma and sequentially treated with chemoradiotherapy and hormonal therapy. Upon the development of metastases, the patient began a 200 mg twice-daily BEZ235 and 2.5 mg weekly everolimus combination regimen. The patient sustained a prolonged stable disease of 18 mo while undergoing the therapy, before his tumor progressed again. Therefore, we sought to both better understand MBC and investigate the underlying molecular mechanisms of the patient's sensitivity and subsequent resistance to the BEZ235/everolimus combination therapy. Genomic and immunohistochemical analyses were performed on samples collected from the initial invasive ductal carcinoma pretreatment and a metastasis postprogression on the BEZ235/everolimus combination treatment. Both tumors were relatively quiet genomically with no overlap to recurrent MBC alterations in the literature. Markers of PI3K/mTOR pathway hyperactivation were not identified in the pretreatment sample, which complements previous reports of HR(+) female breast cancers being responsive to mTOR inhibition without this activation. The postprogression sample, however, demonstrated greater than fivefold increased estrogen receptor and pathogenesis-related protein expression, which could have constrained the PI3K/mTOR pathway inhibition by BEZ235/everolimus. Overall, these analyses have augmented the limited episteme on MBC genetics and treatment

    The SSDC Role in the LICIACube Mission: Data Management and the MATISSE Tool

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    Light Italian Cubesat for Imaging of Asteroids (LICIACube) is an Italian mission managed by the Italian Space Agency (ASI) and part of the NASA Double Asteroid Redirection Test (DART) planetary defense mission. Its main goals are to document the effects of the DART impact on Dimorphos, the secondary member of the (65803) Didymos binary asteroid system, characterizing the shape of the target body and performing dedicated scientific investigations on it. Within this framework, the mission Science Operations Center will be managed by the Space Science Data Center (ASI-SSDC), which will have the responsibility of processing, archiving, and disseminating the data acquired by the two LICIACube onboard cameras. In order to better accomplish this task, SSDC also plans to use and modify its scientific webtool Multi-purpose Advanced Tool for Instruments for the solar system Exploration (MATISSE), making it the primary tool for the LICIACube data analysis, thanks to its advanced capabilities for searching and visualizing data, particularly useful for the irregular shapes common to several small bodies

    A pharmacoeconomic analysis from Italian guidelines for the management of prolactinomas

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    Background: Prolactinoma, the most common pituitary adenoma, is usually treated with dopamine agonist (DA) therapy like cabergoline. Surgery is second-line therapy, and radiotherapy is used if surgical treatment fails or in relapsing macroprolactinoma. Objective: This study aimed to provide economic evidence for the management of prolactinoma in Italy, using a cost-of-illness and cost-utility analysis that considered various treatment options, including cabergoline, bromocriptine, temozolomide, radiation therapy, and surgical strategies. Methods: The researchers conducted a systematic literature review for each research question on scientific data- bases and surveyed a panel of experts for each therapeutic procedure's specific drivers that contributed to its total cost. Results: The average cost of the first year of treatment was euro2,558.91 and euro3,287.40 for subjects with micro- prolactinoma and macroprolactinoma, respectively. Follow-up costs from the second to the fifth year after ini- tial treatment were euro798.13 and euro1,084.59 per year in both groups. Cabergoline had an adequate cost-utility profile, with an incremental cost-effectiveness ratio (ICER) of euro3,201.15 compared to bromocriptine, based on a willingness-to-pay of euro40,000 per quality-adjusted life year (QALY) in the reference economy. Endoscopic sur- gery was more cost-effective than cabergoline, with an ICER of euro44,846.64. Considering a willingness-to-pay of euro40,000/QALY, the baseline findings show cabergoline to have high cost utility and endoscopic surgery just a tad above that. Conclusions: Due to the favorable cost-utility profile and safety of surgical treatment, pituitary surgery should be considered more frequently as the initial therapeutic approach. This management choice could lead to better outcomes and an appropriate allocation of healthcare resources

    VADER: Probing the Dark Side of Dimorphos with LICIACube LUKE

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    The ASI cubesat LICIACube has been part of the first planetary defense mission DART, having among its scopes to complement the DRACO images to better constrain the Dimorphos shape. LICIACube had two different cameras, LEIA and LUKE, and to accomplish its goal, it exploited the unique possibility of acquiring images of the Dimorphos hemisphere not seen by DART from a vantage point of view, in both time and space. This work is indeed aimed at constraining the tridimensional shape of Dimorphos, starting from both LUKE images of the nonimpacted hemisphere of Dimorphos and the results obtained by DART looking at the impacted hemisphere. To this aim, we developed a semiautomatic Computer Vision algorithm, named VADER, able to identify objects of interest on the basis of physical characteristics, subsequently used as input to retrieve the shape of the ellipse projected in the LUKE images analyzed. Thanks to this shape, we then extracted information about the Dimorphos ellipsoid by applying a series of quantitative geometric considerations. Although the solution space coming from this analysis includes the triaxial ellipsoid found by using DART images, we cannot discard the possibility that Dimorphos has a more elongated shape, more similar to what is expected from previous theories and observations. The result of our work seems therefore to emphasize the unique value of the LICIACube mission and its images, making even clearer the need of having different points of view to accurately define the shape of an asteroid.This work was supported by the Italian Space Agency (ASI) within the LICIACube project (ASI-INAF agreement AC No. 2019-31-HH.0) and by the DART mission, NASA contract 80MSFC20D0004
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