136 research outputs found
Smartphone Overuse from Iranian University Students’ Perspective: A Qualitative Study
Background: Smartphone usage has increasing during recent years. Since its excessive use can have negativeconsequences, it is important to know how users use it and become dependent on it. This study was aimed atexploring how university students use their phones, how they depend on them, and the possibleconsequences of overusing them.Methods: This study was conducted using a qualitative design and with a thematic analysis method. Datawere collected using 3 focus group discussions regarding experiences of using smartphones among 22smartphone owners who reported smartphone overuse. They were chosen through snowball sampling at aUniversity of Medical Sciences in Tehran (Iran).Findings: Based on the analysis, the 3 categories of process usage (sub-categories: doing daily routines,information seeking, to take a picture or video, entertainment, academic work, making money, to escapereal-life, and passing the time), social usage (sub-categories: relationship with family, relationship withfriends, interact with the opposite gender, to be seen and heard, approval seeking, and free expression), anddisadvantages (sub-categories: interference with other essential activities, decreased face-to-facecommunications, overdependence, automatic use, loss of sense of time, stress, fatigue, sleep disturbances,physical inactivity, eye problems, high bills, and distraction) were developed.Conclusion: In this research, participants mentioned various uses of their smartphones that enable them tomeet their personal needs and, in spite of the negative consequences of its overuse, cause them to continue touse it. Some uses seem to be affected by environmental and cultural conditions
A GPU-based Correlator X-engine Implemented on the CHIME Pathfinder
We present the design and implementation of a custom GPU-based compute
cluster that provides the correlation X-engine of the CHIME Pathfinder radio
telescope. It is among the largest such systems in operation, correlating
32,896 baselines (256 inputs) over 400MHz of radio bandwidth. Making heavy use
of consumer-grade parts and a custom software stack, the system was developed
at a small fraction of the cost of comparable installations. Unlike existing
GPU backends, this system is built around OpenCL kernels running on
consumer-level AMD GPUs, taking advantage of low-cost hardware and leveraging
packed integer operations to double algorithmic efficiency. The system achieves
the required 105TOPS in a 10kW power envelope, making it among the most
power-efficient X-engines in use today.Comment: 6 pages, 5 figures. Accepted by IEEE ASAP 201
Calibrating CHIME, A New Radio Interferometer to Probe Dark Energy
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit
interferometer currently being built at the Dominion Radio Astrophysical
Observatory (DRAO) in Penticton, BC, Canada. We will use CHIME to map neutral
hydrogen in the frequency range 400 -- 800\,MHz over half of the sky, producing
a measurement of baryon acoustic oscillations (BAO) at redshifts between 0.8 --
2.5 to probe dark energy. We have deployed a pathfinder version of CHIME that
will yield constraints on the BAO power spectrum and provide a test-bed for our
calibration scheme. I will discuss the CHIME calibration requirements and
describe instrumentation we are developing to meet these requirements
Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder
A pathfinder version of CHIME (the Canadian Hydrogen Intensity Mapping
Experiment) is currently being commissioned at the Dominion Radio Astrophysical
Observatory (DRAO) in Penticton, BC. The instrument is a hybrid cylindrical
interferometer designed to measure the large scale neutral hydrogen power
spectrum across the redshift range 0.8 to 2.5. The power spectrum will be used
to measure the baryon acoustic oscillation (BAO) scale across this poorly
probed redshift range where dark energy becomes a significant contributor to
the evolution of the Universe. The instrument revives the cylinder design in
radio astronomy with a wide field survey as a primary goal. Modern low-noise
amplifiers and digital processing remove the necessity for the analog
beamforming that characterized previous designs. The Pathfinder consists of two
cylinders 37\,m long by 20\,m wide oriented north-south for a total collecting
area of 1,500 square meters. The cylinders are stationary with no moving parts,
and form a transit instrument with an instantaneous field of view of
100\,degrees by 1-2\,degrees. Each CHIME Pathfinder cylinder has a
feedline with 64 dual polarization feeds placed every 30\,cm which
Nyquist sample the north-south sky over much of the frequency band. The signals
from each dual-polarization feed are independently amplified, filtered to
400-800\,MHz, and directly sampled at 800\,MSps using 8 bits. The correlator is
an FX design, where the Fourier transform channelization is performed in FPGAs,
which are interfaced to a set of GPUs that compute the correlation matrix. The
CHIME Pathfinder is a 1/10th scale prototype version of CHIME and is designed
to detect the BAO feature and constrain the distance-redshift relation.Comment: 20 pages, 12 figures. submitted to Proc. SPIE, Astronomical
Telescopes + Instrumentation (2014
Inducible proteolytic inactivation of OPA1 mediated by the OMA1 protease in mammalian cells
A proteolytic cascade ensures that OMA1 cleaves and inactivates mitochondrial fusion protein OPA1 in times of stress, preventing damaged mitochondria from fusing with healthy organelles. (See also companion paper from Ehses et al. in this issue.
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