2,852 research outputs found
Towards Anisotropy-Free and Non-Singular Bounce Cosmology with Scale-invariant Perturbations
We investigate non-singular bounce realizations in the framework of
ghost-free generalized Galileon cosmology, which furthermore can be free of the
anisotropy problem. Considering an Ekpyrotic-like potential we can obtain a
total Equation-of-State (EoS) larger than one in the contracting phase, which
is necessary for the evolution to be stable against small anisotropic
fluctuations. Since such a large EoS forbids the Galileon field to generate the
desired form of perturbations, we additionally introduce the curvaton field
which can in general produce the observed nearly scale-invariant spectrum. In
particular, we provide approximate analytical and exact semi-analytical
expressions under which the bouncing scenario is consistent with observations.
Finally, the combined Galileon-curvaton system is free of the Big-Rip after the
bounce.Comment: 13 pages, 9 figure
Fast and broadband fiber dispersion measurement with dense wavelength sampling
We report on a method to obtain dispersion measurements from spectral-domain low-coherence interferograms which enables high accuracy (~ps/(nm·km)), broadband measurements and the determination of very dense (up to 20 points/nm over 500 nm) data sets for both dispersion and dispersion slope. The method exploits a novel phase extraction algorithm which allows the phase associated with each sampling point of the interferogram to be calculated and provides for very accurate results as well as a fast measurement capability, enabling close to real time measurements. The important issue of mitigating the measurement errors due to any residual dispersion of optical elements and to environmental fluctuations was also addressed. We performed systematic measurements on standard fibers which illustrate the accuracy and precision of the technique, and we demonstrated its general applicability to challenging problems by measuring a carefully selected set of microstructured fibers: a lead silicate W-type fiber with a flat, near-zero dispersion profile; a hollow core photonic bandgap fiber with strongly wavelength dependent dispersion and dispersion slope; a small core, highly birefringent index guiding microstructured fiber, for which polarization resolved measurements over an exceptionally wide (~1000 nm) wavelength interval were obtained
Negotiating the female successor-leader role within family business succession in China
This article explores the approaches of identity construction used by Chinese daughters while negotiating the successor–leader role within family businesses. A qualitative interpretivist approach was adopted to understand daughter views on gender, family business leadership and succession, as well as the approaches adopted to negotiate the role of female successor/leader in the Chinese family business. Twenty semi-structured interviews were conducted with both actual and potential female successors. Three approaches of identity construction emerged based on the degree of conformity to traditional gender roles and Confucian family values: first, to abide by conventional gender expectations and perceive themselves as a temporary leader; second, to act as the ‘second leader’ and remain involved in decision making and third, to challenge conventional gender roles and strive to be an independent leader. This article contributes to debates on women in family business and gendered identity construction of daughters in family business in the Chinese context
Quasi-analytical solutions for APSIDAL motion in the three-body problem: Sun - minor planet - Jupiter
This paper deals with the effect of a third body on the apsidal motion of two bodies. The specific case involves a third body-planet Jupiter and the apsidal line motion of a minor planet that orbits the Sun and has its apsidal line go through the major axis of an ellipse. The third body (Jupiter) which satisfies the Langrangian solution will affect the apsidal line motion and therefore affects the ascending and descending motions of the minor planet. In this case no analytical solutions can be obtained, and therefore specific assumptions are made along with numerical solutions. For convenience, we adopt the Lagrangian solution in the three-body problem and obtain quasi-analytical results, which are used to evaluate the effect of the planet on the d Omega/dt (Omega ascending node) of each minor planet. This method is beneficial for improving our knowledge of the orbital elements of the asteroids, and perhaps even much smaller effects such as the effects of the planets on the interplanetary dust complex. Information on the latter may be provided by using this method to investigate Jupiter\u27s effect on the inclination of the symmetry surface of the zodiacal dust cloud
Aphids on Cruciferous Crops: Identification and Management
8 pp., 24 color photos, 6 illustrationsAt least five species of aphids attack cruciferous crops (cabbage, collards, cauliflower, broccoli, kale and others). This publication explains the characteristics that can help producers identify aphids and the damage they cause. Suggestions for scouting, management and control are included, along with an illustrated key to aphid identification
Chaotic Gas Accretion by Black Holes Embedded in AGN Discs as Cause of Low-spin Signatures in Gravitational Wave Events
Accretion discs around super-massive black holes (SMBH) not only power active
galactic nuclei (AGNs), but also host single and binary embedded stellar-mass
black holes (EBHs) that grow rapidly from gas accretion. The merger of these
EBHs provides a promising mechanism for the excitation of some gravitational
wave events observed by LIGO-Virgo, especially those with source masses
considerably larger than isolated stellar-mass black hole binaries. In addition
to their mass and mass-ratio distribution, their hitherto enigmatic small
spin-parameters chi_effective carry important clues and stringent constraints
on their formation channels and evolutionary pathways. Here we show that,
between each coalescence, the typical rapid spin of the merged EBHs is
suppressed by their subsequent accretion of gas from a turbulent environment,
due to its ability to randomize the flow's spin orientation with respect to
that of the EBHs on an eddy-turnover timescale. This theory provides supporting
evidence for the prolificacy of EBH mergers and suggests that their mass growth
may be dominated by gas accretion rather than their coalescence in AGN discs.Comment: accepted by MNRAS, 11 pages, 8 figure
The effect of different baryons impurities
We demonstrate the different effect of different baryons impurities on the
static properties of nuclei within the framework of the relativistic mean-field
model. Systematic calculations show that and has the
same attracting role as hyperon does in lighter hypernuclei.
and hyperon has the attracting role only for the protons
distribution, and has a repulsive role for the neutrons distribution. On the
contrary, and hyperon attracts surrounding neutrons and
reveals a repulsive force to the protons. We find that the different effect of
different baryons impurities on the nuclear core is due to the different third
component of their isospin.Comment: 9 page
Progress in Personalizing Chemotherapy for Bladder Cancer
Platinum-based chemotherapy is commonly used for the treatment of locally advanced and metastatic bladder cancer. However, there are currently no methods to predict chemotherapy response in this disease setting. A better understanding of the biology of bladder cancer has led to developments of molecular biomarkers that may help guide clinical decision making. These biomarkers, while promising, have not yet been validated in prospective trials and are not ready for clinical applications. As alkylating agents, platinum drugs kill cancer cells mainly through induction of DNA damage. A microdosing approach is currently being tested to determine if chemoresistance can be identified by measuring platinum-induced DNA damage using highly sensitive accelerator mass spectrometry technology. The hope is that these emerging strategies will help pave the road towards personalized therapy in advanced bladder cancer
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