Application of the Micro Pixel Photon Counter to calorimetry and PET

Technological solutions are being investigated, in both fields of calorimetry and positron emission tomography, to increase the granularity of the detectors and achieve a better imaging resolution. The Geiger-mode avalanche photodiode looks a promising photo-detector for these compact designs. Up to now, the main limit of its application was the detection of the scintillation light, mostly ranging in the blue region: the traditional Geiger-mode avalanche photodiode is green sensitive. Hamamatsu has recently released a photo-detector of the same family, the Micro Pixel Photon Counter (MPPC), with a high photo-detection efficiency in the 420nm spectral region, opening a new scenario for the scintillator-based systems. The direct readout performances of a MPPC directly coupled to a plastic organic scintillator and to an inorganic scintillator (LSO) are systematically studied. Possible applications in highly granular calorimeters and positron emission tomography detectors are discussed

Kinetically Consistent Data Assimilation for Plant PET Sparse Time Activity Curve Signals

Time activity curve (TAC) signal processing in plant positron emission tomography (PET) is a frontier nuclear science technique to bring out the quantitative fluid dynamic (FD) flow parameters of the plant vascular system and generate knowledge on crops and their sustainable management, facing the accelerating global climate change. The sparse space-time sampling of the TAC signal impairs the extraction of the FD variables, which can be determined only as averaged values with existing techniques. A data-driven approach based on a reliable FD model has never been formulated. A novel sparse data assimilation digital signal processing method is proposed, with the unique capability of a direct computation of the dynamic evolution of noise correlations between estimated and measured variables, by taking into explicit account the numerical diffusion due to the sparse sampling. The sequential time-stepping procedure estimates the spatial profile of the velocity, the diffusion coefficient and the compartmental exchange rates along the plant stem from the TAC signals. To illustrate the performance of the method, we report an example of the measurement of transport mechanisms in zucchini sprouts

Kinetically Consistent Data Assimilation for Plant PET Sparse Time Activity Curve Signals

Time activity curve (TAC) signal processing in plant positron emission tomography (PET) is a frontier nuclear science technique to bring out the quantitative fluid dynamic (FD) flow parameters of the plant vascular system and generate knowledge on crops and their sustainable management, facing the accelerating global climate change. The sparse space-time sampling of the TAC signal impairs the extraction of the FD variables, which can be determined only as averaged values with existing techniques. A data-driven approach based on a reliable FD model has never been formulated. A novel sparse data assimilation digital signal processing method is proposed, with the unique capability of a direct computation of the dynamic evolution of noise correlations between estimated and measured variables, by taking into explicit account the numerical diffusion due to the sparse sampling. The sequential time-stepping procedure estimates the spatial profile of the velocity, the diffusion coefficient and the compartmental exchange rates along the plant stem from the TAC signals. To illustrate the performance of the method, we report an example of the measurement of transport mechanisms in zucchini sprouts

Risk of cardiovascular disease morbidity and mortality in frail and pre-frail older adults : Results from a meta-analysis and exploratory meta-regression analysis

Frailty is common and associated with poorer outcomes in the elderly, but its role as potential cardiovascular disease (CVD) risk factor requires clarification. We thus aimed to meta-analytically evaluate the evidence of frailty and pre-frailty as risk factors for CVD. Two reviewers selected all studies comparing data about CVD prevalence or incidence rates between frail/pre-frail vs. robust. The association between frailty status and CVD in cross-sectional studies was explored by calculating and pooling crude and adjusted odds ratios (ORs)+/- 95% confidence intervals (CIs); the data from longitudinal studies were pooled using the adjusted hazard ratios (HRs). Eighteen cohorts with a total of 31,343 participants were meta-analyzed. Using estimates from 10 cross-sectional cohorts, both frailty and pre-frailty were associated with higher odds of CVD than robust participants. Longitudinal data were obtained from 6 prospective cohort studies. After a median follow-up of 4.4 years, we identified an increased risk for faster onset of any type CVD in the frail (HR= 1.70 [95%CI, 1.18-2.45]; I-2 = 66%) and pre-frail (HR= 1.23 [95%CI, 1.07-1.36]; I-2 = 67%) vs. robust groups. Similar results were apparent for time to CVD mortality in the frail and pre-frail groups. In conclusion, frailty and pre-frailty constitute addressable and independent risk factors for CVD in older adults. (C) 2017 Elsevier B.V. All rights reserved.Peer reviewe

Impact of structural features of very thin stents implanted in unprotected left main or coronary bifurcations on clinical outcomes

Objectives: To evaluate the independent clinical impact of stent structural features in a large cohort of patients undergoing unprotected left main (ULM) or coronary bifurcation percutaneous coronary intervention (PCI) with a range of very thin strut stents. Background: Clinical impact of structural features of contemporary stents remains to be defined. Methods: All consecutive patients enrolled in the veRy thin stents for patients with left mAIn or bifurcatioN in real life (RAIN) registry were included. The following stent structural features were studied: antiproliferative drugs (everolimus vs. sirolimus vs. zotarolimus), strut material (platinum-chromium vs. cobalt-chromium), polymer (bioresorbable vs. durable), number of crowns (<8 vs. ≥8) and number of connectors (<3 vs. ≥3). For small diameter stents (≤2.5 mm), struct thickness (74 vs. 80/81 μm) was also tested. Target lesion failure (TLF), a composite of target lesion revascularization and stent thrombosis, was the primary endpoint. Multivariate analysis was performed with Cox regression models. Results: Out of 2,707 patients, 110 (4.1%) experienced a TLF event after 16 months (12–18). After adjustment for confounders, an increased number of connectors (adjusted hazard ratio [adj-HR] 0.62, 95% confidence interval (CI) 0.39–0.99, p =.04) reduced risk of TLF, driven by stents with ≥2.5 mm diameter (HR 0.54, 95% CI 0.32–0.93, p =.02). This independent relationship was lost for stents with diameter <2.5 mm, where only strut thickness appeared to impact. Conversely, no independent relationship of polymer type, number of crowns, and the specific limus-family eluted drug with outcomes was observed. Conclusions: Among a range of contemporary very thin stent models, an increased number of connectors improved device-related outcomes in this investigated high-risk procedural setting

Incidence of adverse events at 3 months versus at 12 months after dual antiplatelet therapy cessation in patients treated with thin stents with unprotected left main or coronary bifurcations

Incidence and predictors of adverse events after dual antiplatelet therapy (DAPT) cessation in patients treated with thin stents (<100 microns) in unprotected left main (ULM) or coronary bifurcation remain undefined. All consecutive patients presenting with a critical lesion of an ULM or involving a main coronary bifurcation who were treated with very thin strut stents were included. MACE (a composite end point of cardiovascular death, myocardial infarction [MI], target lesion revascularization [TLR], and stent thrombosis [ST]) was the primary endpoint, whereas target vessel revascularization (TVR) was the secondary endpoint, with particular attention to type and occurrence of ST and occurrence of ST, CV death, and MI during DAPT or after DAPT discontinuation. All analyses were performed according to length of DAPT dividing the patients in 3 groups: Short DAPT (3-months), intermediate DAPT (3 to 12 months), and long DAPT (12-months). A total of 117 patients were discharged with an indication for DAPT ≤3 months (median 1: 1 to 2.5), 200 for DAPT between 3 and 12 months (median 8: 7 to 10), and 1,958 with 12 months DAPT. After 12.8 months (8 to 20), MACE was significantly higher in the 3-month group compared with 3 to 12 and 12-month groups (9.4% vs 4.0% vs 7.2%, p ≤0.001), mainly driven by MI (4.4% vs 1.5% vs 3%, p ≤0.001) and overall ST (4.3% vs 1.5% vs 1.8%, p ≤0.001). Independent predictors of MACE were low GFR and a 2 stent strategy. Independent predictors of ST were DAPT duration <3 months and the use of a 2-stent strategy. In conclusion, even stents with very thin strut when implanted in real-life ULM or coronary bifurcation patients discharged with short DAPT have a relevant risk of ST, which remains high although not significant after DAPT cessation

Daily risk of adverse outcomes in patients undergoing complex lesions revascularization: a subgroup analysis from the RAIN-CARDIOGROUP VII study (veRy thin stents for patients with left mAIn or bifurcatioN in real life)

Introduction: Percutaneous coronary intervention (PCI) for complex lesions, including unprotected left main (ULM) and bifurcations, is gaining a relevant role in treating coronary artery disease with good outcomes, also thanks to new generation stents. The daily risk of adverse cardiovascular events and their temporal distribution after these procedures is not known.Methods: All consecutive patients presenting with a critical lesion of ULM or bifurcation treated with very thin struts stents, enrolled in the RAIN-Cardiogroup VII study, were analyzed. The daily risk of major acute cardiovascular events (MACE), target lesion revascularization (TLR) and stent thrombosis (ST) and their temporal distribution in the first year of follow-up was the primary endpoint. Differences among subgroups (ULM, patient presentation, kind of stent polymer) were the secondary endpoint.Results: 2745 patients were included, mean age 68 ± 11 years, 33.3% diabetics, 54.5% had an acute coronary syndrome (ACS); 88.5% of treated lesions were bifurcations, 27.2% ULM. Average daily risk was 0.022% for MACE, 0.005% for TLR and 0.004% for ST, in the first year. Bimodal distribution of adverse events, especially TLR, with an early peak in the first 50 days and a late one after 150 days, was observed. Patients with ULM presented a significantly higher daily risk of events, and ACS patients presented higher MACE risk. No difference emerged according to the type of stent polymer.Conclusions: The daily risk of adverse events in the first year after complex PCI in our study is acceptably low. PCI on ULM carries a higher risk of complications

Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron

The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of $\sqrt s =1.96$ TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is $A_{\mathrm{FB}}^{t\bar{t}} = 0.128 \pm 0.025$. The combined inclusive and differential asymmetries are consistent with recent standard model predictions