ASTRI SST-2M: the design evolution from the prototype to the array telescope

The Cherenkov Telescope Array (CTA) observatory will represent the new frontier of imaging atmospheric Cherenkov Telescope. The simultaneous use of large, medium and small telescopes (respectively LST, MST and SST) will allow to explore the astronomy related to the very high energy domain, typical of Gamma rays, with a sensitivity, angular resolution and image quality never seen before. Within this project, ASTRI, the Italian 2 mirrors Schwarzshild-Couder configuration Small SST led by Italian National Institute of Astronomy (INAF), has moved quickly developing a 4m class telescope prototype which has been tested with results which demonstrates excellent performance as well as wide margins for further improvements. On the basis of the experiences made on the prototype, this paper focus on the design enhancements carried out for the telescope which will be part of the Cherenkov Telescope Array

The ASTRI SST-2M prototype for the Cherenkov Telescope Array: status after the commissioning phase of the telescope

ASTRI SST-2M is an imaging atmospheric Cherenkov telescope developed by the Italian National Institute of Astrophysics (INAF) in the framework of the Cherenkov Telescope Array (CTA) project as an end-to-end prototype for the Small Size array. Large-, medium-, and small-sized telescopes will compose the CTA observatory that represents the next generation of imaging atmospheric Cherenkov telescopes and will explore the very high-energy domain from a few tens of GeV up to few hundreds of TeV. The ASTRI SST-2M telescope has been installed at the INAF-Catania observing station at Serra La Nave, on Mt. Etna (Sicily, Italy) in September 2014. In these 3 years of open-air operations the telescope has been commissioned and its opto-mechanical performance is now well understood. The apparatus was made ready to host its main scientific instrument, the camera with Silicon-Photomultiplier based detectors. This contribution is a status report on the complete ASTRI SST-2M telescope assembly including the electro-mechanical structure and the optical system

The ASTRI SST-2M prototype for the Cherenkov Telescope Array: opto-mechanical performance

ASTRI SST-2M is an end-to-end telescope prototype developed by the Italian National Institute of Astrophysics (INAF) in the framework of the Cherenkov Telescope Array (CTA). The CTA observatory, with a combination of large-, medium-, and small-sized telescopes (LST, MST and SST, respectively), will represent the next generation of imaging atmospheric Cherenkov telescopes. It will explore the very high-energy domain from a few tens of GeV up to few hundreds of TeV. The ASTRI SST-2M telescope structure and mirrors have been installed at the INAF observing station at Serra La Nave, on Mt. Etna (Sicily, Italy) in September 2014. Its performance verification phase began in autumn 2015. Part of the scheduled activities foresees the study and characterization of the optical and opto-mechanical performance of the telescope prototype. In this contribution we report the results achieved in terms of kinematic model analysis, mirrors reflectivity evolution, telescopes positioning, flexures and pointing model and the thermal behavior

Exploring the paradoxical relationship of a Creb 3 Regulatory Factor missense variant with body mass index and diabetes among Samoans: Protocol for the Soifua Manuia (Good Health) observational cohort study

Background:The prevalence of obesity and diabetes in Samoa, like many other Pacific Island nations, has reached epidemic proportions. Although the etiology of these conditions can be largely attributed to the rapidly changing economic and nutritional environment, a recently identified genetic variant, rs373863828 (CREB 3 regulatory factor, CREBRF: c.1370G>A p.[R457Q]) is associated with increased odds of obesity, but paradoxically, decreased odds of diabetes.Objective:The overarching goal of the Soifua Manuia (Good Health) study was to precisely characterize the association of the CREBRF variant with metabolic (body composition and glucose homeostasis) and behavioral traits (dietary intake, physical activity, sleep, and weight control behaviors) that influence energy homeostasis in 500 adults.Methods:A cohort of adult Samoans who participated in a genome-wide association study of adiposity in Samoa in 2010 was followed up, based on the presence or absence of the CREBRF variant, between August 2017 and March 2019. Over a period of 7-10 days, each participant completed the main study protocol, which consisted of anthropometric measurements (weight, height, circumferences, and skinfolds), body composition assessment (bioelectrical impedance and dual-energy x-ray absorptiometry), point-of-care glycated hemoglobin measurement, a fasting blood draw and oral glucose tolerance test, urine collection, blood pressure measurement, hand grip strength measurement, objective physical activity and sleep apnea monitoring, and questionnaire measures (eg, health interview, cigarette and alcohol use, food frequency questionnaire, socioeconomic position, stress, social support, food and water insecurity, sleep, body image, and dietary preferences). In January 2019, a subsample of the study participants (n=118) completed a buttock fat biopsy procedure to collect subcutaneous adipose tissue samples.Results:Enrollment of 519 participants was completed in March 2019. Data analyses are ongoing, with results expected in 2020 and 2021.Conclusions:While the genetic variant rs373863828, in CREBRF, has the largest known effect size of any identified common obesity gene, very little is currently understood about the mechanisms by which it confers increased odds of obesity but paradoxically lowered odds of type 2 diabetes. The results of this study will provide insights into how the gene functions on a whole-body level, which could provide novel targets to prevent or treat obesity, diabetes, and associated metabolic disorders. This study represents the human arm of a comprehensive and integrated approach involving humans as well as preclinical models that will provide novel insights into metabolic disease