14,415 research outputs found
Hydrodynamics of polymers in an active bath
The conformational and dynamical properties of active polymers in solution
are determined by the nature of the activity, and the behavior of polymers with
self-propelled, active Brownian particle-type monomers differs qualitatively
from that of polymers with monomers driven externally by colored noise forces.
We present simulation and theoretical results for polymers in solution in the
presence of external active noise. In simulations, a semiflexible bead-spring
chain is considered, in analytical calculations, a continuous linear wormlike
chain. Activity is taken into account by independent monomer/site velocities,
with orientations changing in a diffusive manner. In simulations, hydrodynamic
interactions (HI) are taken into account by the Rotne-Prager-Yamakawa tensor,
or by an implementation of the active polymer in the multiparticle collision
dynamics approach for fluids. To arrive at an analytical solution, the
preaveraged Oseen tensor is employed. The active process implies a dependence
of the stationary-state properties on HI via polymer relaxation times. With
increasing activity, HI lead to an enhanced swelling of flexible polymers, and
the conformational properties differ substantially from those of polymers with
self-propelled monomers in presence of HI or free-draining polymers. The
polymer mean square displacement is enhanced by HI. Over a wide range of time
scales, hydrodynamics leads to a subdiffusive regime of the site mean square
displacement for flexible active polymers, with an exponent of (5/7), larger
than that of the Rouse (1/2) and Zimm (2/3) models of passive polymers.Comment: 16 pages, 11 figure
Lower Cretaceous (Hauterivian-Albian) ammonite biostratigraphy in the Maestrat Basin (E Spain)
Peer reviewedPublisher PD
Active Brownian filaments with hydrodynamic interactions: conformations and dynamics
The conformational and dynamical properties of active self-propelled
filaments/polymers are investigated in the presence of hydrodynamic
interactions by both, Brownian dynamics simulations and analytical theory.
Numerically, a discrete linear chain composed of active Brownian particles is
considered, analytically, a continuous linear semiflexible polymer with active
velocities changing diffusively. The force-free nature of active monomers is
accounted for - no Stokeslet fluid flow induced by active forces - and higher
order hydrodynamic multipole moments are neglected. The nonequilibrium
character of the active process implies a dependence of the stationary-state
properties on HI via the polymer relaxation times. In particular, at moderate
activities, HI lead to a substantial shrinkage of flexible and semiflexible
polymers to an extent far beyond shrinkage of comparable free-draining
polymers; even flexible HI-polymers shrink, while active free-draining polymers
swell monotonically. Large activities imply a reswelling, however, to a less
extent than for non-HI polymers, caused by the shorter polymer relaxation times
due to hydrodynamic interactions. The polymer mean square displacement is
enhanced, and an activity-determined ballistic regime appears. Over a wide
range of time scales, flexible active polymers exhibit a hydrodynamically
governed subdiffusive regime, with an exponent significantly smaller than that
of the Rouse and Zimm models of passive polymers. Compared to simulations, the
approximate analytical approach predicts a weaker hydrodynamic effect
Overcoming triple-negative breast cancer (TNBC) resistance to oncolytic virotherapy by histone deacetylase inhibitor, trichostatin A
"Triple-negative breast cancer (TNBC) is a tumor classification that lack receptors for the hormones estrogen, progesterone and HER2 protein. These malignancies are characterized to be of poor prognosis, refractoriness to conventional therapy and high rates of recurrence. Virotherapy with oncolytic adenovirus (OAd) consists of cancer selective viruses that replicate, spread, and kill cancer cells by oncolysis, without affecting the normal cells."--Introduction
Tunable Graphene Electronics with Local Ultrahigh Pressure
We achieve fine tuning of graphene effective doping by applying ultrahigh
pressures (> 10 GPa) using Atomic Force Microscopy (AFM) diamond tips. Specific
areas in graphene flakes are irreversibly flattened against a SiO2 substrate.
Our work represents the first demonstration of local creation of very stable
effective p-doped graphene regions with nanometer precision, as unambiguously
verified by a battery of techniques. Importantly, the doping strength depends
monotonically on the applied pressure, allowing a controlled tuning of graphene
electronics. Through this doping effect, ultrahigh pressure modifications
include the possibility of selectively modifying graphene areas to improve
their electrical contact with metal electrodes, as shown by Conductive AFM.
Density Functional Theory calculations and experimental data suggest that this
pressure level induces the onset of covalent bonding between graphene and the
underlying SiO2 substrate. Our work opens a convenient avenue to tuning the
electronics of 2D materials and van der Waals heterostructures through pressure
with nanometer resolution
The effect of CEO incentives on deviations from institutional norms in foreign market expansion decisions: Behavioral agency and cross-border acquisitions
CEO incentives have been the subject of great interest for human resource scholars. We explore the institutional context within which the CEO makes sense of their incentives. Our theory suggests that CEO equity incentives interact with institutional norms to influence foreign market entry choices. Specifically, we argue that CEOs will weigh the risk bearing created by equity incentives, along with the consequences of legitimacy loss, when deciding whether to deviate from institutional norms when internationalizing. In doing so, we advance human resource literature by demonstrating that CEO responses to incentives are influenced by institutional norms and that CEOs' decisions to deviate from institutional norms are shaped by their incentives. We find support for our framework in the analysis of the stake taken by acquirers in 4,184 cross-border acquisitions
Connections between epsilon'/epsilon and Rare Kaon Decays in Supersymmetry
We analyze the rare kaon decays , , and in conjunction
with the CP violating ratio in a general class of
supersymmetric models in which - and magnetic-penguin contributions can be
substantially larger than in the Standard Model. We point out that radiative
effects relate the double left-right mass insertion to the single left-left
one, and that the phenomenological constraints on the latter reflect into a
stringent bound on the supersymmetric contribution to the penguin. Using
this bound, and those coming from recent data on we find
{\rm BR}(K_L \to \pi^0 \nu \bar \nu)\lsim 1.2\cdot 10^{-10}, {\rm BR}(K^+
\to \pi^+ \nu \bar \nu)\lsim 1.7\cdot 10^{-10}, {\rm BR}(K_L \to \pi^0 e^+
e^-)_{\rm dir}\lsim 2.0\cdot 10^{-11}, assuming the usual determination of the
CKM parameters and neglecting the possibility of cancellations among different
supersymmetric effects in . Larger values are possible, in
principle, but rather unlikely. We stress the importance of a measurement of
these three branching ratios, together with improved data and improved theory
of , in order to shed light on the realization of various
supersymmetric scenarios. We reemphasize that the most natural enhancement of
, within supersymmetric models, comes from chromomagnetic
penguins and show that in this case sizable enhancements of can also be expected.Comment: 40 pages, 5 figure
Substrate orientation dependence on the solid phase epitaxial growth rate of Ge
The solid phase epitaxial growth process has been studied at 330 °C by transmission electron microscopy for Ge wafers polished at 10°–15° increments from the [001] to [011] orientations. The velocity showed a strong dependence on substrate orientation with the [001] direction displaying a velocity 16 times greater than the [111] direction. A lattice kinetic Monte Carlo model was used to simulate solid phase epitaxial growth (SPEG) rates at different orientations, and simulations compared well with experimental results. Cross sectional transmission electron microscopy and plan view transmission electron microscopy revealed stacking fault and twin defect formation in the [111] orientation where all other orientations showed only hairpin dislocations. The twin defects formed from Ge SPEG were comparatively less dense than what has previously been reported for Si, which gave rise to higher normalized velocities and a constant [111] SPEG velocity for Ge.The authors acknowledge Intel Corporation for funding
this work. I.M.-B. acknowledges funding from the European
project MASTIC (PCIG09-GA-2011-293783)
Searches for Lepton Flavour Violation at a Linear Collider
We investigate the prospects for detection of lepton flavour violation in
sparticle production and decays at a Linear Collider (LC), in models guided by
neutrino oscillation data. We consider both slepton pair production and
sleptons arising from the cascade decays of non-leptonic sparticles. We study
the expected signals when lepton-flavour-violating (LFV) interactions are
induced by renormalization effects in the Constrained Minimal Supersymmetric
extension of the Standard Model (CMSSM), focusing on the subset of the
supersymmetric parameter space that also leads to cosmologically interesting
values of the relic neutralino LSP density. Emphasis is given to the
complementarity between the LC, which is sensitive to mixing in both the left
and right slepton sectors, and the LHC, which is sensitive primarily to mixing
in the right sector. We also emphasize the complementarity between searches for
rare LFV processes at the LC and in low-energy experiments.Comment: 19 pages, 10 figure
The Port service area project, Santander: Central state and local authority intervention in the planning and development of a port-side industrial zone
This article reports on a case study research project that examines the planning and development of a port-side industrial zone in the Franco era in Santander, Spain. The case study illustrates some key features of central and local authority intervention in the area, which may be of value and interest to planners and politicians working in similar politico-administrative environments. The study concludes that, as regards plan implementation, the development of the Port Service Area involved contravention of the statutory approved urban plan for the area and irregularities in planning procedure. Despite these shortcomings, the development of the Port Service Area has been an economic and strategic success
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