The radial velocity method is a very productive technique used to detect and confirm extrasolar planets. The most recent spectrographs, such as ESPRESSO or EXPRES, have the potential to detect ...Earth-like planets around Sun-like stars. However, stellar activity can induce radial velocity variations that dilute or even mimic the signature of a planet. A widely recognized method for disentangling these signals is to model the radial velocity time series, jointly with stellar activity indicators, using Gaussian processes and their derivatives. However, such modeling is prohibitive in terms of computational resources for large data sets, as the cost typically scales as the total number of measurements cubed. Here, we present S+LEAF 2, a Gaussian process framework that can be used to jointly model several time series, with a computational cost that scales linearly with the data set size. This framework thus provides a state-of-the-art Gaussian process model, with tractable computations even for large data sets. We illustrate the power of this framework by reanalyzing the 246 HARPS radial velocity measurements of the nearby K2 dwarf HD 13808, together with two activity indicators. We reproduce the results of a previous analysis of these data, but with a strongly decreased computational cost (more than two order of magnitude). The gain would be even greater for larger data sets.
Efficient modeling of correlated noise Delisle, J.-B.; Hara, N.; Ségransan, D.
Astronomy and astrophysics (Berlin),
03/2020, Letnik:
635
Journal Article
Recenzirano
Periodograms are common tools used to search for periodic signals in unevenly spaced time series. The significance of periodogram peaks is often assessed using false alarm probability (FAP), which in ...most studies assumes uncorrelated noise and is computed using numerical methods such as bootstrapping or Monte Carlo. These methods have a high computational cost, especially for low FAP levels, which are of most interest. We present an analytical estimate of the FAP of the periodogram in the presence of correlated noise, which is fundamental to analyze astronomical time series correctly. The analytical estimate that we derive provides a very good approximation of the FAP at a much lower cost than numerical methods. We validate our analytical approach by comparing it with Monte Carlo simulations. Finally, we discuss the sensitivity of the method to different assumptions in the modeling of the noise.
Immunotherapy is the only available treatment for metastatic renal cell cancer (RCC), but the response rate is only about 20% and the treatment is occasionally associated with severe adverse effects. ...Thus, the selection of patients with a high susceptibility to immunotherapy is needed; however, there is no promising molecular marker that can predict the response to immunotherapy for RCC. This study was carried out to elucidate the potential role of apoptosis-related molecules Bcl-2 and Fas, as well as apoptotic and proliferating indexes (AI, PI) as predictors of the susceptibility of metastatic RCC to immunotherapy. Immunohistochemical examination of tumour tissues from 40 patients with metastatic RCC undergoing postoperative immunotherapy after radical nephrectomy was performed. Patients with progressive disease (PD) after immunotherapy presented with decreased survival (P=0.006). Progressive disease correlated with higher PI in the primary lesion (P=0.0087). All primary tumours of CR or PR patients were negative for Bcl-2, whereas among NC+PD patients, 40.6% were positive for Bcl-2 (P=0.0373). Patients in whom the primary tumours were both Bcl-2- and Fas-negative showed significantly better responses to immunotherapy in comparison with the remaining group (P=0.0022). The Bcl-2 and Fas status of the primary lesion may become useful criteria for the selection of patients with metastatic RCC for immunotherapy.
The incidence of apoptosis and the expression of Fas antigen (Fas)/Fas ligand (FasL) mRNA in bleomycin-induced pulmonary fibrosis in mice were examined. Male ICR mice were intratracheally instilled ...with bleomycin (5 U/kg of body weight). The controls were injected with sterile saline. The animals were anesthetized and killed at 1, 6, and 12 h, and 1, 3, 5, 7, 9, and 14 days after bleomycin instillation. We assessed the incidence of apoptosis in lung tissues by DNA fragmentation on agarose gel electrophoresis, terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end-labeling, and electron microscopy. The expression of Fas and FasL mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). The localization of Fas mRNA was analyzed by in situ hybridization and that of FasL mRNA was analyzed by RT in situ PCR. The results showed that (1) a single instillation of bleomycin leads to the rapid appearance of apoptosis in bronchial and alveolar epithelial cells, which resolves within 1 day, and (2) apoptosis reappears on day 7 and continues for over 14 days after bleomycin instillation. This was accompanied with a progression of fibrosis. Corticosteroid administration completely blocked both apoptosis and fibrosis. The expression of Fas mRNA was upregulated in the alveolar epithelial cells by the bleomycin instillation. FasL mRNA was also upregulated in infiltrating lymphocytes after bleomycin treatment, but not in the control mice. The administration of corticosteroids suppressed the expression of Fas and FasL mRNA as well as apoptosis and fibrosis. Although these results do not show that apoptosis mediated by the Fas/FasL system is directly linked to bleomycin-induced fibrosis, we speculate that excessive apoptosis and the Fas/FasL system play a role in the pathogenesis of bleomycin-induced lung injury.
Efficient modeling of correlated noise Delisle, J.-B.; Unger, N.; Hara, N. C. ...
Astronomy and astrophysics (Berlin),
03/2022, Letnik:
659
Journal Article
Recenzirano
The radial velocity method is a very productive technique used to detect and confirm extrasolar planets. The most recent spectrographs, such as ESPRESSO or EXPRES, have the potential to detect ...Earth-like planets around Sun-like stars. However, stellar activity can induce radial velocity variations that dilute or even mimic the signature of a planet. A widely recognized method for disentangling these signals is to model the radial velocity time series, jointly with stellar activity indicators, using Gaussian processes and their derivatives. However, such modeling is prohibitive in terms of computational resources for large data sets, as the cost typically scales as the total number of measurements cubed. Here, we present
S+LEAF
2, a Gaussian process framework that can be used to jointly model several time series, with a computational cost that scales linearly with the data set size. This framework thus provides a state-of-the-art Gaussian process model, with tractable computations even for large data sets. We illustrate the power of this framework by reanalyzing the 246 HARPS radial velocity measurements of the nearby K2 dwarf HD 138038, together with two activity indicators. We reproduce the results of a previous analysis of these data, but with a strongly decreased computational cost (more than two order of magnitude). The gain would be even greater for larger data sets.
Objective: In 2005, the University of California, San Francisco developed the Cancer of the Prostate Risk Assessment (UCSF-CAPRA) score as a new risk stratification tool. The UCSF-CAPRA, which ranges ...from 0 to 10 points, consists of five clinical variables, prostate-specific antigen, Gleason score, T stage, percent of positive biopsies and age. The aim of this study was to validate the UCSF-CAPRA score for Japanese prostate cancer patients receiving radical prostatectomy using the contemporary Gleason grading.
Methods
From 1999 to 2010, 211 men who underwent radical prostatectomy were used for validation. Biochemical progression-free survival was calculated using the Kaplan-Meier method and the UCSF-CAPRA and D'Amico risk categories were compared using the log-rank method. The concordance index (c-index) for the UCSF-CAPRA and D'Amico risk classification was calculated.
Results
Using the UCSF-CAPRA score, 85 (40.3%), 106 (50.2%) and 20 (9.5%) subjects were stratified as 0-2 points (low risk), 3-5 points (intermediate risk) and 6-10 points (high risk). Using the D'Amico risk criteria, 66 (31.3%), 89 (42.2%) and 56 (26.5%) were stratified as low-, intermediate- and high-risk groups, respectively. The Kaplan-Meier analysis showed that the UCSF-CAPRA divided the patients significantly into each risk category. There was no significant difference between low and intermediate in the D'Amico risk classification. The c-index of the UCSF-CAPRA and D'Amico classification was 0.755 and 0.713, respectively.
Conclusion
The UCSF-CAPRA is an acceptable risk category tool comparable to that of the D'Amico risk classification for Japanese prostate cancer patients receiving radical prostatectomy in the contemporary Gleason grading era.
The effects of post-welding heat treatment (PWHT) at temperatures ranging from 640°C to 750°C for 1 h on the mechanical and metallographical properties of a dissimilar-metal electron beam weld (EBW) ...joint of reduced activation ferritic/martensitic steel, F82H, and SUS316L austenitic stainless steel were investigated. The EBW joint is demarcated into five regions: the base metal of F82H (F82H-BM), the heat-affected zone of F82H (F82H-HAZ), the interlayer at the edge of F82H-HAZ (IL), the weld metal (WM), and the base metal of SUS316L (SUS316L-BM). No hardening resulting from welding and no significant change in the hardness resulting from PWHT above 640°C were observed in the F82H-BM, SUS316L-BM and WM. However, a significantly higher hardness was observed in the as-welded F82H-HAZ and IL than in other regions, and a significant reduction in hardness occurred in F82H-HAZ and IL, as a result of PWHT above 640°C. Irradiation hardening after PWHT at 720°C was investigated using proton-irradiation at 300°C up to 0.1 and 1 dpa. The irradiation hardening of the WM, IL and SUS316L-BM, which was less than that of the as-received SUS316L, was much larger than that of F82H-HAZ and F82H-BM.
This letter presents details of high-performance enhancement-mode GaN MIS high-electron-mobility transistor (MIS-HEMT) devices. Devices with an n-GaN/i-AlN/n-GaN triple cap layer, a recessed-gate ...structure, and high- k gate dielectrics show high drain current and complete enhancement-mode operation. The maximum drain current and threshold voltage ( V th ) are 800 mA/mm and +3 V, respectively. These results indicate that a recessed AlGaN/GaN MIS-HEMT with the triple cap could be a promising new technology for future device applications.
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