10,862 research outputs found
Quantum generalized Reed-Solomon codes: Unified framework for quantum MDS codes
We construct a new family of quantum MDS codes from classical generalized
Reed-Solomon codes and derive the necessary and sufficient condition under
which these quantum codes exist. We also give code bounds and show how to
construct them analytically. We find that existing quantum MDS codes can be
unified under these codes in the sense that when a quantum MDS code exists,
then a quantum code of this type with the same parameters also exists. Thus as
far as is known at present, they are the most important family of quantum MDS
codes.Comment: 9 pages, no figure
Controllability of nonlinear fractional delay dynamical systems with prescribed controls
In this paper, we consider controllability of nonlinear fractional delay dynamical systems with prescribed controls. We firstly give the solution representation of the fractional delay dynamical systems using Laplace transform and Mittag–Leffler functions. Then we give necessary and sufficient conditions for the controllability criteria of linear fractional delay dynamical systems with prescribed controls. Further, we use a fixed point theorem to establish the sufficient condition for the controllability of nonlinear fractional delay dynamical systems with prescribed controls. In particular, we determine several sufficient conditions on the nonlinear function term so that if the linear system is controllable, then the nonlinear system is controllable. Finally, we give two examples to demonstrate the applicability of our obtained results
The magnetic phase diagram of underdoped YBa2Cu3Oy inferred from torque magnetization and thermal conductivity
Strong evidence for charge-density correlation in the underdoped phase of the
cuprate YBa2Cu3Oy was obtained by nuclear magnetic resonance (NMR) and resonant
x-ray scatter- ing. The fluctuations were found to be enhanced in strong
magnetic fields. Recently, 3D (three dimensional) charge-density wave (CDW)
formation with long-range order (LRO) was observed by x-ray diffraction in H
>15 T. To elucidate how the CDW transition impacts the pair condensate, we have
used torque magnetization to 45 T and thermal conductivity to
construct the magnetic phase diagram in untwinned crystals with hole density p
= 0.11. We show that the 3D CDW transitions appear as sharp features in the
susceptibility and at the fields HK and Hp, which define phase
boundaries in agreement with spectroscopic techniques. From measurements of the
melting field Hm(T) of the vortex solid, we obtain evidence for two vortex
solid states below 8 K. At 0.5 K, the pair condensate appears to adjust to the
3D CDW by a sharp transition at 24 T between two vortex solids with very
different shear moduli. At even higher H (42 T) the second vortex solid melts
to a vortex liquid which survives to fields well above 45 T. de Haas-van Alphen
oscillations appear at fields 24-28 T, below the lower bound for the upper
critical field Hc2.Comment: 7 pages, 8 figures; New version of previous posting, reporting torque
measurements to 45 Tesla and final magnetic phase diagra
Characterizing mixed mode oscillations shaped by noise and bifurcation structure
Many neuronal systems and models display a certain class of mixed mode
oscillations (MMOs) consisting of periods of small amplitude oscillations
interspersed with spikes. Various models with different underlying mechanisms
have been proposed to generate this type of behavior. Stochastic versions of
these models can produce similarly looking time series, often with noise-driven
mechanisms different from those of the deterministic models. We present a suite
of measures which, when applied to the time series, serves to distinguish
models and classify routes to producing MMOs, such as noise-induced
oscillations or delay bifurcation. By focusing on the subthreshold
oscillations, we analyze the interspike interval density, trends in the
amplitude and a coherence measure. We develop these measures on a biophysical
model for stellate cells and a phenomenological FitzHugh-Nagumo-type model and
apply them on related models. The analysis highlights the influence of model
parameters and reset and return mechanisms in the context of a novel approach
using noise level to distinguish model types and MMO mechanisms. Ultimately, we
indicate how the suite of measures can be applied to experimental time series
to reveal the underlying dynamical structure, while exploiting either the
intrinsic noise of the system or tunable extrinsic noise.Comment: 22 page
Statistical Origin of Constituent-Quark Scaling in the QGP hadronization
Nonextensive statistics in a Blast-Wave model (TBW) is implemented to
describe the identified hadron production in relativistic p+p and
nucleus-nucleus collisions. Incorporating the core and corona components within
the TBW formalism allows us to describe simultaneously some of the major
observations in hadronic observables at the Relativistic Heavy-Ion Collider
(RHIC): the Number of Constituent Quark Scaling (NCQ), the large radial and
elliptic flow, the effect of gluon saturation and the suppression of hadron
production at high transverse momentum (pT) due to jet quenching. In this
formalism, the NCQ scaling at RHIC appears as a consequence of non-equilibrium
process. Our study also provides concise reference distributions with a least
chi2 fit of the available experimental data for future experiments and models.Comment: 4 pages, 3 figures; added two tables, explained a little bit more on
TBW_p
Revealing nascent proteomics in signaling pathways and cell differentiation.
Regulation of gene expression at the level of protein synthesis is a crucial element in driving how the genetic landscape is expressed. However, we are still limited in technologies that can quantitatively capture the immediate proteomic changes that allow cells to respond to specific stimuli. Here, we present a method to capture and identify nascent proteomes in situ across different cell types without disturbing normal growth conditions, using O-propargyl-puromycin (OPP). Cell-permeable OPP rapidly labels nascent elongating polypeptides, which are subsequently conjugated to biotin-azide, using click chemistry, and captured with streptavidin beads, followed by digestion and analysis, using liquid chromatography-tandem mass spectrometry. Our technique of OPP-mediated identification (OPP-ID) allows detection of widespread proteomic changes within a short 2-hour pulse of OPP. We illustrate our technique by recapitulating alterations of proteomic networks induced by a potent mammalian target of rapamycin inhibitor, MLN128. In addition, by employing OPP-ID, we identify more than 2,100 proteins and uncover distinct protein networks underlying early erythroid progenitor and differentiation states not amenable to alternative approaches such as amino acid analog labeling. We present OPP-ID as a method to quantitatively identify nascent proteomes across an array of biological contexts while preserving the subtleties directing signaling in the native cellular environment
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