28,719 research outputs found
Higgs bosons of a supersymmetric model at the Large Hadron Collider
It is found that CP symmetry may be explicitly broken in the Higgs sector of
a supersymmetric model with two extra neutral gauge bosons at the
one-loop level. The phenomenology of the model, the Higgs sector in particular,
is studied for a reasonable parameter space of the model, in the presence of
explicit CP violation at the one-loop level. At least one of the neutral Higgs
bosons of the model might be produced via the fusion process at the Large
Hadron Collider.Comment: 23 pages, 5 figures, JHE
FeAs-based superconductivity: a case study of the effects of transition metal doping on BaFe2As2
The recently discovered FeAs-based superconductors are a new, promising set
of materials for both technological as well as basic research. They offer
transition temperatures as high as 55 K as well as essentially isotropic and
extremely large upper, superconducting critical fields in excess of 40 T at 20
K. In addition they may well provide insight into exotic superconductivity that
extends beyond just FeAs-based superconductivity, perhaps even shedding light
on the still perplexing CuO-based high-Tc materials. Whereas superconductivity
can be induced in the RFeAsO (R = rare earth) and AEFe2As2 (AE = Ba, Sr, Ca))
families by a number of means, transition metal doping of BaFe2As2, e.g.
Ba(Fe1-xTMx)2As2, offers the easiest experimental access to a wide set of
materials. In this review we present an overview and summary of the effect of
TM doping (TM = Co, Ni, Cu, Pd, and Rh) on BaFe2As2. The resulting phase
diagrams reveal the nature of the interaction between the structural, magnetic
and superconducting phase transitions in these compounds and delineate a region
of phase space that allows for the stabilization of superconductivity.Comment: edited and shortened version is accepted to AR:Condensed Matter
Physic
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Imbibition dynamics of nano-particulate ink-jet drops on micro-porous media
Ink-jet printing of nano-metallic colloidal fluids on to
porous media such as coated papers has become a viable
method to produce conductive tracks for low-cost,
disposable printed electronic devices. However, the
formation of well-defined and functional tracks on an
absorbing surface is controlled by the drop imbibition
dynamics in addition to the well-studied post-impact drop
spreading behavior.
This study represents the first investigation of the realtime
imbibition of ink-jet deposited nano-Cu colloid drops
on to coated paper substrates. In addition, the same ink was
deposited on to a non-porous polymer surface as a control
substrate. By using high-speed video imaging to capture the
deposition of ink-jet drops, the time-scales of drop
spreading and imbibition were quantified and compared
with model predictions. The influences of the coating pore
size on the bulk absorption rate and nano-Cu particle
distribution have also been studied
Camera for QUasars in EArly uNiverse (CQUEAN)
We describe the overall characteristics and the performance of an optical CCD
camera system, Camera for QUasars in EArly uNiverse (CQUEAN), which is being
used at the 2.1 m Otto Struve Telescope of the McDonald Observatory since 2010
August. CQUEAN was developed for follow-up imaging observations of red sources
such as high redshift quasar candidates (z >= 5), Gamma Ray Bursts, brown
dwarfs, and young stellar objects. For efficient observations of the red
objects, CQUEAN has a science camera with a deep depletion CCD chip which
boasts a higher quantum efficiency at 0.7 - 1.1 um than conventional CCD chips.
The camera was developed in a short time scale (~ one year), and has been
working reliably. By employing an auto-guiding system and a focal reducer to
enhance the field of view on the classical Cassegrain focus, we achieve a
stable guiding in 20 minute exposures, an imaging quality with FWHM >= 0.6"
over the whole field (4.8' * 4.8'), and a limiting magnitude of z = 23.4 AB mag
at 5-sigma with one hour total integration time.Comment: Accepted for publication in PASP. 26 pages including 5 tables and 24
figure
Langevin Trajectories between Fixed Concentrations
We consider the trajectories of particles diffusing between two infinite
baths of fixed concentrations connected by a channel, e.g. a protein channel of
a biological membrane. The steady state influx and efflux of Langevin
trajectories at the boundaries of a finite volume containing the channel and
parts of the two baths is replicated by termination of outgoing trajectories
and injection according to a residual phase space density. We present a
simulation scheme that maintains averaged fixed concentrations without creating
spurious boundary layers, consistent with the assumed physics
Growth factor restriction impedes progression of wound healing following cataract surgery: identification of VEGF as a putative therapeutic target
Secondary visual loss occurs in millions of patients due to a wound-healing response, known as posterior capsule opacification (PCO), following cataract surgery. An intraocular lens (IOL) is implanted into residual lens tissue, known as the capsular bag, following cataract removal. Standard IOLs allow the anterior and posterior capsules to become physically connected. This places pressure on the IOL and improves contact with the underlying posterior capsule. New open bag IOL designs separate the anterior capsule and posterior capsules and further reduce PCO incidence. It is hypothesised that this results from reduced cytokine availability due to greater irrigation of the bag. We therefore explored the role of growth factor restriction on PCO using human lens cell and tissue culture models. We demonstrate that cytokine dilution, by increasing medium volume, significantly reduced cell coverage in both closed and open capsular bag models. This coincided with reduced cell density and myofibroblast formation. A screen of 27 cytokines identified nine candidates whose expression profile correlated with growth. In particular, VEGF was found to regulate cell survival, growth and myofibroblast formation. VEGF provides a therapeutic target to further manage PCO development and will yield best results when used in conjunction with open bag IOL designs
Jetted mixtures of particle suspensions and resins
This is the author accepted manuscript. The final version is available from AIP at http://scitation.aip.org/content/aip/journal/pof2/26/10/10.1063/1.4897238.Drop-on-demand (DoD) ink-jetting of hard particle suspensions with volume fraction Φ ~ 0.25 has been surveyed using 1000 ultra-high speed videos as a function of particle size (d90 = 0.8-3.6 µm), with added 2 wt% acrylic (250 kDa) or 0.5 wt% cellulose (370 kDa) resin, and also compared with Newtonian analogues. Jet break-off times from 80 µm diameter nozzles were insensitive (120±10 µs) to particle size, and resin jet break-off times were not significantly altered by > 30 wt% added particles. Different particle size grades can be jetted equally well in practice, while resin content effectively controls DoD break-off times
Focusing and Compression of Ultrashort Pulses through Scattering Media
Light scattering in inhomogeneous media induces wavefront distortions which
pose an inherent limitation in many optical applications. Examples range from
microscopy and nanosurgery to astronomy. In recent years, ongoing efforts have
made the correction of spatial distortions possible by wavefront shaping
techniques. However, when ultrashort pulses are employed scattering induces
temporal distortions which hinder their use in nonlinear processes such as in
multiphoton microscopy and quantum control experiments. Here we show that
correction of both spatial and temporal distortions can be attained by
manipulating only the spatial degrees of freedom of the incident wavefront.
Moreover, by optimizing a nonlinear signal the refocused pulse can be shorter
than the input pulse. We demonstrate focusing of 100fs pulses through a 1mm
thick brain tissue, and 1000-fold enhancement of a localized two-photon
fluorescence signal. Our results open up new possibilities for optical
manipulation and nonlinear imaging in scattering media
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Nanoindentation Of Si Nanostructures: Buckling And Friction At Nanoscales
A nanoindentation system was employed to characterize mechanical properties of silicon nanolines (SiNLs), which were fabricated by an anisotropic wet etching (AWE) process. The SiNLs had the linewidth ranging from 24 nm to 90 nm, having smooth and vertical sidewalls and the aspect ratio (height/linewidth) from 7 to 18. During indentation, a buckling instability was observed at a critical load, followed by a displacement burst without a load increase, then a full recovery of displacement upon unloading. This phenomenon was explained by two bucking modes. It was also found that the difference in friction at the contact between the indenter and SiNLs directly affected buckling response of these nanolines. The friction coefficient was estimated to be in a range of 0.02 to 0.05. For experiments with large indentation displacements, irrecoverable indentation displacements were observed due to fracture of Si nanolines, with the strain to failure estimated to be from 3.8% to 9.7%. These observations indicated that the buckling behavior of SiNLs depended on the combined effects of load, line geometry, and the friction at contact. This study demonstrated a valuable approach to fabrication of well-defined Si nanoline structures and the application of the nanoindentation method for investigation of their mechanical properties at the nanoscale.Microelectronics Research Cente
Analysis of cybersecurity threats in Industry 4.0: the case of intrusion detection
Nowadays, industrial control systems are experiencing a new revolution with the interconnection of the operational equipment with the Internet, and the introduction of cutting-edge technologies such as Cloud Computing or Big data within the organization. These and other technologies are paving the way to the Industry 4.0. However, the advent of these technologies, and the innovative services that are enabled by them, will also bring novel threats whose impact needs to be understood. As a result, this paper provides an analysis of the evolution of these cyber-security issues and the requirements that must be satis ed by intrusion detection defense mechanisms in this context.Springer ; Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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