7,065 research outputs found
A Macroeconomic Overview of Public Enterprise in the Philippines, 1975-84
This paper provides an overview of the macroeconomic role and impact of Philippine public enterprises. In particular, it deals with its economic contribution on value-added, investment and employment. It also discusses the sector’s deficit and the impact of its finance on the national budget and borrowings. Its efficiency, as indicated by financial profitability is measured as well.public debt, public enterprise, employment opportunities, gross value added
Active redundancy allocation in systems
An effective way of improving the reliability of a system is the
allocation of active redundancy. Let , be independent
lifetimes of the components and , respectively, which
form a series system. Let denote and , where X
is the lifetime of a redundancy (say S) independent of and
. That is denote the lifetime of a system
obtained by allocating S to as an active redundancy.
Singh and Misra (1994) considered the criterion where is
preferred to for redundancy allocation if . In this paper we use the same
criterion of Singh and Misra (1994) and we investigate the
allocation of one active redundancy when it differs depending on the
component with which it is to be allocated. We find sufficient
conditions for the optimization which depend on the components and
redundancies probability distributions. We also compare the
allocation of two active redundancies (say and ) in
two different ways, that is with and with
and viceversa. For this case the hazard rate order plays an
important role. We obtain results for the allocation of more than
two active redundancies to a k-out-of-n systems
Quantum MERA Channels
Tensor networks representations of many-body quantum systems can be described
in terms of quantum channels. We focus on channels associated with the
Multi-scale Entanglement Renormalization Ansatz (MERA) tensor network that has
been recently introduced to efficiently describe critical systems. Our approach
allows us to compute the MERA correspondent to the thermodynamic limit of a
critical system introducing a transfer matrix formalism, and to relate the
system critical exponents to the convergence rates of the associated channels.Comment: 4 pages, 2 figure
Quantum relative positioning in Hilbert space
A new class of state transformations that are quantum mechanically prohibited
is introduced. These can be seen as the generalization of the universal-NOT
transformation which, for all pure inputs state of a given Hilbert space
produces pure outputs whose projection on the original state is fixed to a
value smaller than one. The case of not pure output states is also addressed.
We give an application of these transformations in the context of separability
criteria.Comment: 5 pages, 1 figure; new material added: in particular we present an
application of quantum movers in the context of separability criteria. Typos
corrected. Phys. Rev. A, accepted for publicatio
Unifying approach to the quantification of bipartite correlations by Bures distance
The notion of distance defined on the set of states of a composite quantum
system can be used to quantify total, quantum and classical correlations in a
unifying way. We provide new closed formulae for classical and total
correlations of two-qubit Bell-diagonal states by considering the Bures
distance. Complementing the known corresponding expressions for entanglement
and more general quantum correlations, we thus complete the quantitative
hierarchy of Bures correlations for Bell-diagonal states. We then explicitly
calculate Bures correlations for two relevant families of states: Werner states
and rank-2 Bell-diagonal states, highlighting the subadditivity which holds for
total correlations with respect to the sum of classical and quantum ones when
using Bures distance. Finally, we analyse a dynamical model of two independent
qubits locally exposed to non-dissipative decoherence channels, where both
quantum and classical correlations measured by Bures distance exhibit freezing
phenomena, in analogy with other known quantifiers of correlations.Comment: 18 pages, 4 figures; published versio
Relations between entanglement and purity in non-Markovian dynamics
Knowledge of the relationships among different features of quantumness, like
entanglement and state purity, is important from both fundamental and practical
viewpoints. Yet, this issue remains little explored in dynamical contexts for
open quantum systems. We address this problem by studying the dynamics of
entanglement and purity for two-qubit systems using paradigmatic models of
radiation-matter interaction, with a qubit being isolated from the environment
(spectator configuration). We show the effects of the corresponding local
quantum channels on an initial two-qubit pure entangled state in the
concurrence-purity diagram and find the conditions which enable dynamical
closed formulas of concurrence, used to quantify entanglement, as a function of
purity. We finally discuss the usefulness of these relations in assessing
entanglement and purity thresholds which allow noisy quantum teleportation. Our
results provide new insights about how different properties of composite open
quantum systems behave and relate each other during quantum evolutions.Comment: 16 Pages, 10 Figures. One author added. Improved version with more
references and comment
Dopamine receptor expression and function in the normal and pathological hypothalamus-pituitary-adrenal axis
__Abstract__
Dopamine is the predominant catecholamine neurotransmitter in the human central
nervous system, where it controls a variety of functions including cognition,
emotion, locomotor activity, food intake and endocrine regulation. Dopamine also
plays multiple roles in the periphery as a modulator of cardiovascular and renal
function, gastrointestinal motility and the endocrine system (1). Dopamine exerts its
functions via the binding with dopamine receptors (1). Dopamine receptors belong
to the family of seven transmembrane domain G protein-coupled receptors and
include five different receptor subtypes, named D1-Ds. The members of dopamine
receptor family are encoded by genes localized on different chromosome loci,
displaying a considerable homology in their protein structure and function. The
analysis of dopamine receptor structure and function suggests the existence of two
different groups of receptors: D1-like, including D1 and D5 receptors, associated to a
stimulatory function, and Dz-like, including Dz, D3 and D4 receptors, associated to
an inhibitory function. The D1 and Ds receptors are encoded by intronless genes
and share an 80% homology in their transmembrane domains. The Dz receptor
shares a 75% homology with the D3 and a 53% homology with the D4
transmembrane domains and all three receptor subtypes are encoded by genes,
which are interrupted by introns. The Dz receptor exists in two main variants, called
Dzlong and Dzshort, generated by an alternative splicing of an 87 base pairs exon.
These two D2 receptor isoforms differ for the presence or absence of a stretch of 29
amino acids in the third cytoplasmic loop in their protein structure. Splicing variants
of the D3 receptor encoding nonfunctional proteins have been also identified. The
analysis of the D4 receptor reveals the existence of polymorphic variations within
the coding sequence, being a 48 base pairs sequence existent as a direct repeat
sequence (D4.1), fourfold (D4.4), sevenfold (D4.7) or eleven fold (D4.11) repeat
sequence. Therefore, the D4 receptor isoforms differ for the length of the third
cytoplasmic loop and have one, four, seven or eleven times the same insert of a
stretch of 19 amino acids in their protein structure. The Ds receptor has two related
pseudogenes, which share a 95% homology with the gene and encode for truncated
non functional forms of the receptor (1). The molecular characteristics of human
dopamine receptor family are summarized in Table 1. A schematic representation
of the human dopamine receptor is shown in Fig. 1
Superconducting Fluctuation Corrections to the Thermal Current in Granular Metals
The first-order superconducting fluctuation corrections to the thermal
conductivity of a granular metal are calculated. A suppression of thermal
conductivity proportional to is observed in a region not too
close to the critical temperature . As , a saturation of the
correction is found, and its sign depends on the ratio between the barrier
transparency and the critical temperature. In both regimes, the Wiedemann-Franz
law is violated.Comment: 9 pages, 7 figures. Replaced with published version. Important
change
- …