134 research outputs found
Epidemiology of the human immunodeficiency virus in Saudi Arabia; 18-year surveillance results and prevention from an Islamic perspective
BACKGROUND: data on HIV epidemiology and preventive measures in Islamic countries is limited. This study describes the results of 18-year of HIV surveillance in Saudi Arabia (SA) and the preventive measures implemented from an Islamic perspective. METHODS: surveillance for HIV has been underway in SA since 1984. Indications for HIV testing include clinical suspicion, screening of contacts of HIV-infected patients, and routine screening of blood and organ donors, prisoners, intravenous drug users, patients with other sexually transmitted infections, and expatriates pre-employment. This is a case series descriptive study of all confirmed HIV infections diagnosed in SA from 1984 through 2001. RESULTS: a total of 6046 HIV infections were diagnosed, of which 1285 (21.3%) cases were Saudi citizens. Over the 18-year surveillance period the number of HIV infections diagnosed annually among Saudi citizens gradually increased and, over the period 1997â2001, it reached to 84 to 142 cases per year. The number of cases per 100,000 population varied widely between regions with a maximum of 74 cases and a minimum of 2 cases. The infection was most common in the age group 20â40 years (74.6%) and predominantly affected men (71.6%). The modes of transmission among Saudi citizens and expatriates, respectively, were as follows: heterosexual contact, 487 (37.9%) and 1352 (28.4%) cases; blood transfusion, 322 (25.0%) and 186 (3.9%) cases; perinatal transmission, 83 (6.5%) and 19 (0.4%) cases; homosexual contact, 32 (2.5%) and 38 (0.8%) cases; intravenous drug use, 17 (1.3%) and 33 (0.7%) cases; bisexual contact, 10 (0.8%) and 14 (0.3%) cases; unknown, 334 (26.0%) and 3119 (65.5%) cases. The number of HIV infections transmitted by blood or blood products transfusion declined to zero by year 2001 and all such infections occurred due to transfusions administered before 1986. At HIV diagnosis, 4502/6046 (74.5%) patients had no symptoms, 787 (13.0%) patients had non-AIDS defining manifestations, and 757 (12.5%) patients had AIDS. A total of 514/1285 (40%) Saudi patients died by year 2001. CONCLUSIONS: the number of HIV cases in SA is limited with heterosexual contact being the main mode of transmission. From an Islamic perspective, preventive strategies include prevention of non-marital sex and intravenous drug use with encouragement of "safe sex" through legal marriage
Performance of a small size telescope (SST-1M) camera for gamma-ray astronomy with the Cherenkov Telescope Array
The foreseen implementations of the Small Size Telescopes (SST) in CTA will
provide unique insights into the highest energy gamma rays offering fundamental
means to discover and under- stand the sources populating the Galaxy and our
local neighborhood. Aiming at such a goal, the SST-1M is one of the three
different implementations that are being prototyped and tested for CTA. SST-1M
is a Davies-Cotton single mirror telescope equipped with a unique camera
technology based on SiPMs with demonstrated advantages over classical
photomultipliers in terms of duty-cycle. In this contribution, we describe the
telescope components, the camera, and the trigger and readout system. The
results of the commissioning of the camera using a dedicated test setup are
then presented. The performances of the camera first prototype in terms of
expected trigger rates and trigger efficiencies for different night-sky
background conditions are presented, and the camera response is compared to
end-to-end simulations.Comment: All CTA contributions at arXiv:1709.0348
Development of a strategy for calibrating the novel SiPM camera of the SST-1M telescope proposed for the Cherenkov Telescope Array
CTA will comprise a sub-array of up to 70 small size telescopes (SSTs) at the
southern array. The SST-1M project, a 4 m-diameter Davies Cotton telescope with
9 degrees FoV and a 1296 pixels SiPM camera, is designed to meet the
requirements of the next generation ground based gamma-ray observatory CTA in
the energy range above 3 TeV. Silicon photomultipliers (SiPM) cameras of
gamma-ray telescopes can achieve good performance even during high night sky
background conditions. Defining a fully automated calibration strategy of SiPM
cameras is of great importance for large scale production validation and online
calibration. The SST-1M sub-consortium developed a software compatible with CTA
pipeline software (CTApipe). The calibration of the SST-1M camera is based on
the Camera Test Setup (CTS), a set of LED boards mounted in front of the
camera. The CTS LEDs are operated in pulsed or continuous mode to emulate
signal and night sky background respectively. Continuous and pulsed light data
analysis allows us to extract single pixel calibration parameters to be used
during CTA operation.Comment: All CTA contributions at arXiv:1709.0348
Control Software for the SST-1M Small-Size Telescope prototype for the Cherenkov Telescope Array
The SST-1M is a 4-m Davies--Cotton atmospheric Cherenkov telescope optimized
to provide gamma-ray sensitivity above a few TeV. The SST-1M is proposed as
part of the Small-Size Telescope array for the Cherenkov Telescope Array (CTA),
the first prototype has already been deployed. The SST-1M control software of
all subsystems (active mirror control, drive system, safety system,
photo-detection plane, DigiCam, CCD cameras) and the whole telescope itself
(master controller) uses the standard software design proposed for all CTA
telescopes based on the ALMA Common Software (ACS) developed to control the
Atacama Large Millimeter Array (ALMA). Each subsystem is represented by a
separate ACS component, which handles the communication to and the operation of
the subsystem. Interfacing with the actual hardware is performed via the OPC UA
communication protocol, supported either natively by dedicated industrial
standard servers (PLCs) or separate service applications developed to wrap
lower level protocols (e.g. CAN bus, camera slow control) into OPC UA. Early
operations of the telescope without the camera were already carried out. The
camera is fully assembled and is capable to perform data acquisition using
artificial light source.Comment: In Proceedings of the 35th International Cosmic Ray Conference
(ICRC2017), Busan, Korea. All CTA contributions at arXiv:1709.0348
Large scale characterization and calibration strategy of a SiPM-based camera for gamma-ray astronomy
The SST-1M is a 4-m diameter mirror Davies-Cotton gamma-ray telescope. It has
been designed to cover the energy range above 500 GeV and to be part of an
array of telescopes separated by 150-200 m. Its innovative camera is featuring
large area hexagonal silicon photo-multipliers as photon detectors and a fully
digital trigger and readout system. Here, the strategy and the methods for its
calibration are presented, together with the obtained results. In particular,
the off and on-site calibration strategies are demonstrated on the first camera
prototype. The performances of the camera in terms of charge and time
resolution are described
Optimizing community-driven development through sage tradition in Cameroon
Powering community development requires a re-invention of traditional authority. This paper interrogates this proposition: how does sage tradition engender social resilience and what is the impact of traditional authority on the modern governance architecture? Sage tradition construed culturally as elder-led authority is anchored on wisdom and respect for eldersâa pivotal asset in community development transactions. Informed by indigenous knowledge, social capital and asset-based concepts, an empirical account of strategic leadership by the elderly is proffered, uncovering indigenous governance in the North West Region, Cameroon. A pyramidal power structure validates village elders as key players in advancing social justice. They offer counsel and arbitrate in community affairs and mobilise community members for infrastructure provisionâcommunity halls, equipping schools, digging roads, building bridges and supply of fresh water. Though elder esteemed traditions prove perfunctory, findings show communities are benefiting from the accumulated, incremental cultural assets factored into local development. The paper concludes that thriving cultural assets should be amalgamated through a policy drive that taps into the utility of traditional authority, in synergy with modern state institutions to bolster social development, address poverty and social inequality
Calibration and operation of SiPM-based cameras for gamma-ray astronomy in presence of high night-sky light
The SST-1M project for the Cherenkov Telescope Array
The SST-1M project, run by a Consortium of institutes from Czech Republic, Poland and Switzerland, has been proposed as a solution for implementing the small-size telescope array of the southern site of the Cherenkov Telescope Array. The technology is a pathfinder for efficient production of cost-effective imaging air Cherenkov telescopes. We report on the main system features and recent upgrades, the performances validation and the operation campaign carried out in 2018
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