2,801 research outputs found
Non-adiabatic corrections to elastic scattering of halo nuclei
We derive the formalism for the leading order corrections to the adiabatic
approximation to the scattering of composite projectiles. Assuming a two-body
projectile of core plus loosely-bound valence particle and a model (the core
recoil model) in which the interaction of the valence particle and the target
can be neglected, we derive the non-adiabatic correction terms both exactly,
using a partial wave analysis, and using the eikonal approximation. Along with
the expected energy dependence of the corrections, there is also a strong
dependence on the valence-to-core mass ratio and on the strength of the
imaginary potential for the core-target interaction, which relates to
absorption of the core in its scattering by the target. The strength and
diffuseness of the core-target potential also determine the size of the
corrections. The first order non-adiabatic corrections were found to be smaller
than qualitative estimates would expect. The large absorption associated with
the core-target interaction in such halo nuclei as Be11 kills off most of the
non-adiabatic corrections. We give an improved estimate for the range of
validity of the adiabatic approximation when the valence-target interaction is
neglected, which includes the effect of core absorption. Some consideration was
given to the validity of the eikonal approximation in our calculations.Comment: 14 pages with 10 figures, REVTeX4, AMS-LaTeX v2.13, submitted to
Phys. Rev.
The effects of endosulfan on P450 1A gene expression, antioxidant enzymes activity and histopathological alterations in liver of Persian sturgeon (Acipenser persicus Borodin, 1987)
The effects of 14 days exposure to sublethal concentrations of endosulfan (10 and 40 μg L−1) were investigated in mRNA- P450 1A expression, antioxidant enzymes (SOD and CAT) activity and histopathological alterations of Persian sturgeon (Acipenser persicus) fingerlings with weights of 3–5 g. The results illustrated that the relative mRNA- P450 1A expression level significantly increased (P < 0.05) compared to the control group. Highest significant increase (P < 0.05) was observed on the first day, then decreased towards day 14 of exposure. The SOD and CAT activity showed a significant increase in fish exposed to different concentrations up to day 7, then activity decreased on day 14 in fish of all treated groups. Although signs of tissue lesions were observed on day 4, they increased from day 7 and reached the highest level on day 14. The magnitude of all changed studied parameters (gene expression, enzymes and histopathological) follows a concentration-dependent manner. © 2016 Blackwell Verlag Gmb
Secret key establishment from common randomness represented as complex correlated random processes: Practical algorithms and theoretical limits
Establishing secret common randomness between two or multiple devices in a network resides at the root of communication security. In its most frequent form of key establishment, the problem is traditionally decomposed into a randomness generation stage (randomness purity is subject to employing often costly true random number generators) and an information-exchange agreement stage, which relies either on public-key infrastructure or on symmetric encryption (key wrapping).
This dissertation has been divided into two main parts. In the first part, an algorithm called KERMAN is proposed to establish secret-common-randomness for ad-hoc networks, which works by harvesting randomness directly from the network routing metadata, thus achieving both pure randomness generation and (implicitly) secret-key agreement. This algorithm relies on the route discovery phase of an ad-hoc network employing the Dynamic Source Routing protocol, is lightweight, and requires relatively little communication overhead. The algorithm is evaluated for various network parameters, and different levels of complexity, in OPNET network simulator. The results show that, in just ten minutes, thousands of secret random bits can be generated network-wide, between different pairs in a network of fifty users.
The proposed algorithm described in this first part of this research study has inspired study of the problem of generating a secret key
based on a more practical model to be explored in the second part of this dissertation. Indeed, secret key establishment from common randomness has been traditionally investigated under certain limiting assumptions, of which the most ubiquitous appears to be that the information available to all parties comes in the form of independent and identically distributed (i.i.d.) samples of some correlated andom variables. Unfortunately, models employing the i.i.d assumption are often not accurate representations of real scenarios. A more capable model would represent the available information as correlated hidden Markov models (HMMs), based on the same underlying Markov chain. Such a model accurately reflects the scenario where all parties have access to imperfect observations of the same source random process, exhibiting a certain time dependency. In the second part of the dissertation , a computationally-efficient asymptotic bounds for the secret key capacity of the correlated-HMM scenario has been derived. The main obstacle, not only for this model, but also for other non-i.i.d cases, is the computational complexity. This problem has been addressed by converting the initial bound to a product of Markov random matrices, and using recent results regarding its convergence to a Lyapunov exponent
Effects of an induced three-body force in the incident channel of (d,p) reactions
A widely accepted practice for treating deuteron breakup in
reactions relies on solving a three-body Schr\"odinger equation with
pairwise -, - and - interactions. However, it was shown in
[Phys. Rev. C \textbf{89}, 024605 (2014)] that projection of the many-body
wave function into the three-body channel results in a
complicated three-body operator that cannot be reduced to a sum of pairwise
potentials. It contains explicit contributions from terms that include
interactions between the neutron and proton via excitation of the target .
Such terms are normally neglected. We estimate the first order contribution of
these induced three-body terms and show that applying the adiabatic
approximation to solving the model results in a simple modification of
the two-body nucleon optical potentials. We illustrate the role of these terms
for the case of Ca()Ca transfer reactions at incident
deuteron energies of 11.8, 20 and 56 MeV, using several parameterisations of
nonlocal optical potentials.Comment: 7 pages, 2 figures. Publication due in Phys. Rev.
Effects of date palm fruit extracts on skin mucosal immunity, immune related genes expression and growth performance of common carp (Cyprinus carpio) fry
The aim of this study was to investigate the effects of date palm fruit extracts (DPFE) on skin mucosal immunity, immune related genes expression and growth performance of fry common carp (Cyprinus carpio). One hundred and twenty specimens (4.06 ± 0.13 g) were supplied and allocated into six aquaria; specimens in three aquaria were fed non-supplemented diet (control) while the fish in the other 3 aquaria were fed with DPFE at 200 ml kg-1. At the end of feeding trial (8 weeks) skin mucus immune parameters (total immunoglobulins, lysozyme, protease and alkaline phosphatase activity) and immune related gene expression (tumor necrosis factor α [tnfa], lysozyme [ly] and interleukin-1-beta, [il1b]) in the head-kidney were studied. The results revealed that feeding carp fry with 200 ml kg-1 DPFE remarkably elevated the three skin mucus immune parameters tested (P 0.05) compared to control fish (fed control diet). Furthermore, growth performance parameters were significantly improved in fry fed DPFE (P < 0.05). More studies are needed to understand different aspects of DPFE administration in fry mucosal immunity. © 2015 Elsevier Ltd
Ultrastructure of cytoplasmic fragments in human cleavage stage embryos
Purpose: The goal of this study was to evaluate the ultrastructure of cytoplasmic fragments along with the effect of cytoplasmic fragment and perivitelline space coarse granulation removal (cosmetic microsurgery) from embryos before embryo transfer on ART outcomes. Methods: One hundred and fifty intracytoplasmic sperm injection cycles with male factor infertility were included in this prospective study. Patients were divided into three groups of case (n = 50), sham (n = 50), and control (n = 50). Embryos with 10–50 % fragmentation were included in this study. Cosmetic microsurgery and zona assisted hatching were only performed in case and sham groups respectively. Extracted fragments were evaluated ultrastructurally by transmission electron microscopy (TEM). Rates of clinical pregnancy, live birth, miscarriage, multiple pregnancies, and congenital anomaly in the three groups were also compared. Results: Micrographs from TEM showed that mitochondria were the most abundant structures found in the fragments along with mitochondria-vesicle complexes, Golgi apparatus, primary lysosomes, and vacuoles. There were no significant differences in demographic characteristics, laboratory and clinical data, or embryo morphological features between the groups. The rate of clinical pregnancy in control, sham, and case groups had no significant differences (24, 18, and 18 %, respectively). The rates of live birth, miscarriage, multiple pregnancy, and congenital anomaly were also similar between the different groups. Conclusions: Our data demonstrated that cosmetic microsurgery on preimplantation embryos had no beneficial effect on ART outcomes in unselected groups of patients. As mitochondria are the most abundant organelles found in cytoplasmic fragments, fragment removal should be performed with more caution in embryos with moderate fragmentation
Probing halo nucleus structure through intermediate energy elastic scattering
This work addresses the question of precisely what features of few body
models of halo nuclei are probed by elastic scattering on protons at high
centre-of-mass energies. Our treatment is based on a multiple scattering
expansion of the proton-projectile transition amplitude in a form which is well
adapted to the weakly bound cluster picture of halo nuclei. In the specific
case of Li scattering from protons at 800 MeV/u we show that because
core recoil effects are significant, scattering crosssections can not, in
general, be deduced from knowledge of the total matter density alone.
We advocate that the optical potential concept for the scattering of halo
nuclei on protons should be avoided and that the multiple scattering series for
the full transition amplitude should be used instead.Comment: 8 pages REVTeX, 1 eps figure, accepted for publication in Phys. Rev.
A New Bound on Excess Frequency Noise in Second Harmonic Generation in PPKTP at the 10^-19 Level
We report a bound on the relative frequency fluctuations in nonlinear second
harmonic generation. A 1064nm Nd:YAG laser is used to read out the phase of a
Mach-Zehnder interferometer while PPKTP, a nonlinear crystal, is placed in each
arm to generate second harmonic light. By comparing the arm length difference
of the Mach Zehnder as read out by the fundamental 1064 nm light, and its
second harmonic at 532 nm, we can bound the excess frequency noise introduced
in the harmonic generation process. We report an amplitude spectral density of
frequency noise with total RMS frequency deviation of 3mHz and a minimum value
of 20 {\mu}Hz/rtHz over 250 seconds with a measurement bandwidth of 128 Hz,
corresponding to an Allan deviation of 10^-19 at 20 seconds.Comment: Submitted to Optics Express June 201
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