10,497 research outputs found
Observing the sky at extremely high energies with the Cherenkov Telescope Array: Status of the GCT project
The Cherenkov Telescope Array is the main global project of ground-based
gamma-ray astronomy for the coming decades. Performance will be significantly
improved relative to present instruments, allowing a new insight into the
high-energy Universe [1]. The nominal CTA southern array will include a
sub-array of seventy 4 m telescopes spread over a few square kilometers to
study the sky at extremely high energies, with the opening of a new window in
the multi-TeV energy range. The Gamma-ray Cherenkov Telescope (GCT) is one of
the proposed telescope designs for that sub-array. The GCT prototype recorded
its first Cherenkov light on sky in 2015. After an assessment phase in 2016,
new observations have been performed successfully in 2017. The GCT
collaboration plans to install its first telescopes and cameras on the CTA site
in Chile in 2018-2019 and to contribute a number of telescopes to the
subsequent CTA production phase.Comment: 8 pages, 7 figures, ICRC201
Objectification: impact on adolescent females what do counselors need to know regarding objectification and sexual identiy development to appropriately guide therapeutic work with adolescent females
Master's Project (M.Ed.) University of Alaska Fairbanks, 201
Nonclassical rotational inertia for a supersolid under rotation
As proposed by Leggett [4], the supersolidity of a crystal is characterized
by the Non Classical Rotational Inertia (NCRI) property. Using a model of
quantum crystal introduced by Josserand, Pomeau and Rica [5], we prove that
NCRI occurs. This is done by analyzing the ground state of the aforementioned
model, which is related to a sphere packing problem, and then deriving a
theoretical formula for the inertia momentum. We infer a lower estimate for the
NCRI fraction, which is a landmark of supersolidity
Kolmogorov-Smirnov method for the determination of signal time-shifts
A new method for the determination of electric signal time-shifts is
introduced. As the Kolmogorov-Smirnov test, it is based on the comparison of
the cumulative distribution functions of the reference signal with the test
signal. This method is very fast and thus well suited for on-line applications.
It is robust to noise and its performances in terms of precision are excellent
for time-shifts ranging from a fraction to several sample durations.
PACS. 29.40.Gx (Tracking and position-sensitive detectors), 29.30.Kv (X- and
-ray spectroscopy), 07.50.Qx (Signal processing electronics)Comment: 8 pages, 7 figure
Creep motion of a model frictional system
We report on the dynamics of a model frictional system submitted to minute
external perturbations. The system consists of a chain of sliders connected
through elastic springs that rest on an incline. By introducing cyclic
expansions and contractions of the springs we observe a reptation of the chain.
We account for the average reptation velocity theoretically. The velocity of
small systems exhibits a series of plateaus as a function of the incline angle.
Due to elastic e ects, there exists a critical amplitude below which the
reptation is expected to cease. However, rather than a full stop of the creep,
we observe in numerical simulations a transition between a continuous-creep and
an irregular-creep regime when the critical amplitude is approached. The latter
transition is reminiscent of the transition between the continuous and the
irregular compaction of granular matter submitted to periodic temperature
changes
Fast analytical methods for the correction of signal random time-shifts and application to segmented HPGe detectors
Detection systems rely more and more on on-line or off-line comparison of
detected signals with basis signals in order to determine the characteristics
of the impinging particles. Unfortunately, these comparisons are very sensitive
to the random time shifts that may alter the signal delivered by the detectors.
We present two fast algebraic methods to determine the value of the time shift
and to enhance the reliability of the comparison to the basis signals.Comment: 13 pages, 8 figure
Truncated derived functors and spectral sequences
The term of the Adams spectral sequence may be identified with certain derived functors, and this also holds for a number of other spectral sequences. Our goal is to show how the higher terms of such spectral sequences are determined by truncations of relative derived functors, defined in terms of certain simplicial functors called mapping algebra
Towards Low Cost Coupling Structures for Short-Distance Optical Interconnections
The performance of short distance optical interconnections in general relies
very strongly on coupling structures, since they will determine the overall
efficiency of the system to a large extent. Different configurations can be
considered and a variety of manufacturing technologies can be used. We present
two different discrete and two different integrated coupling components which
can be used to deflect the light beam over 90 degrees and can play a crucial
role when integrating optical interconnections in printed circuit boards. The
fabrication process of the different coupling structures is discussed and
experimental results are shown. The main characteristics of the coupling
structures are given. The main advantages and disadvantages of the different
components are discussed
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