13,512 research outputs found
The Placental Transcriptome in Late Gestational Hypoxia Resulting in Murine Intrauterine Growth Restriction Parallels Increased Risk of Adult Cardiometabolic Disease.
Intrauterine growth restriction (IUGR) enhances risk for adult onset cardiovascular disease (CVD). The mechanisms underlying IUGR are poorly understood, though inadequate blood flow and oxygen/nutrient provision are considered common endpoints. Based on evidence in humans linking IUGR to adult CVD, we hypothesized that in murine pregnancy, maternal late gestational hypoxia (LG-H) exposure resulting in IUGR would result in (1) placental transcriptome changes linked to risk for later CVD, and 2) adult phenotypes of CVD in the IUGR offspring. After subjecting pregnant mice to hypoxia (10.5% oxygen) from gestational day (GD) 14.5 to 18.5, we undertook RNA sequencing from GD19 placentas. Functional analysis suggested multiple changes in structural and functional genes important for placental health and function, with maximal dysregulation involving vascular and nutrient transport pathways. Concordantly, a ~10% decrease in birthweights and ~30% decrease in litter size was observed, supportive of placental insufficiency. We also found that the LG-H IUGR offspring exhibit increased risk for CVD at 4 months of age, manifesting as hypertension, increased abdominal fat, elevated leptin and total cholesterol concentrations. In summary, this animal model of IUGR links the placental transcriptional response to the stressor of gestational hypoxia to increased risk of developing cardiometabolic disease
Efeitos de usos alternativos do solo sobre a população de fungos micorrízicos arbusculares na Amazônia.
bitstream/item/48936/1/Boletim-PD-16-AMAZ-ORIENTAL.pd
Fast Frequency Control Scheme through Adaptive Virtual Inertia Emulation
This paper presents a novel virtual inertia controller for converters in power systems with high share of renewable resources. By combining the analytical study of system dynamics and a Linear-Quadratic Regulator (LQR)-based optimization technique, the optimal state feedback gain is determined, adapting the emulated inertia constant according to the frequency disturbance in the system. The optimality is achieved through trade-off between the critical frequency limits and the required control effort, i.e. utilization of the internal energy storage. The proposed controller is integrated into a state-of-the-art converter control scheme and verified through EMT simulations. The results show a significant improvement in the frequency response compared to an open-loop system, while also preserving drastically more DC-side energy than a non-adaptive controller
Efeito da inoculação com fungos micorrízicos arbusculares em mudas de mangostãozeiro, Garcinia mangostana L.
Publicado também: FRAZÃO, D. A. C.; HOMMA, A. K. O; VIÉGAS, I. de J. M. (Ed.). Contribuição ao desenvolvimento da fruticultura na Amazônia. Belém, PA: Embrapa Amazônia Oriental, 2006. p. 587-592
BMN operators with vector impurities, Z_2 symmetry and pp-waves
We calculate the coefficients of three-point functions of BMN operators with
two vector impurities. We find that these coefficients can be obtained from
those of the three-point functions of scalar BMN operators by interchanging the
coefficient for the symmetric-traceless representation with the coefficient for
the singlet. We conclude that the Z_2 symmetry of the pp-wave string theory is
not manifest at the level of field theory three-point correlators.Comment: 25 pages, 7 figures. v1: A reference and a footnote added; v2: New
contributions found, Z_2 symmetry lost in 3-point function
Time-dependent density functional theory: Past, present, and future
Time-dependent density functional theory (TDDFT) is presently enjoying
enormous popularity in quantum chemistry, as a useful tool for extracting
electronic excited state energies. This article discusses how TDDFT is much
broader in scope, and yields predictions for many more properties. We discuss
some of the challenges involved in making accurate predictions for these
properties.Comment: 12 pages, 4 figure
STM imaging of electronic waves on the surface of BiTe: topologically protected surface states and hexagonal warping effects
Scanning tunneling spectroscopy studies on high-quality BiTe crystals
exhibit perfect correspondence to ARPES data, hence enabling identification of
different regimes measured in the local density of states (LDOS). Oscillations
of LDOS near a step are analyzed. Within the main part of the surface band
oscillations are strongly damped, supporting the hypothesis of topological
protection. At higher energies, as the surface band becomes concave,
oscillations appear which disperse with a particular wave-vector that may
result from an unconventional hexagonal warping term.Comment: 4 pages, 4 figures. Revised manuscript with improved analysis and
figure
A Calculation of the plane wave string Hamiltonian from N=4 super-Yang-Mills theory
Berenstein, Maldacena, and Nastase have proposed, as a limit of the strong
form of the AdS/CFT correspondence, that string theory in a particular plane
wave background is dual to a certain subset of operators in the N=4
super-Yang-Mills theory. Even though this is a priori a strong/weak coupling
duality, the matrix elements of the string theory Hamiltonian, when expressed
in gauge theory variables, are analytic in the 't Hooft coupling constant. This
allows one to conjecture that, like the masses of excited string states, these
can be recovered using perturbation theory in Yang-Mills theory.
In this paper we identify the difference between the generator of scale
transformations and a particular U(1) R-symmetry generator as the operator dual
to the string theory Hamiltonian for nonvanishing string coupling. We compute
its matrix elements and find that they agree with the string theory prediction
provided that the state-operator map is modified for nonvanishing string
coupling. We construct this map explicitly and calculate the anomalous
dimensions of the new operators. We identify the component arising from the
modification of the state-operator map with the contribution of the string
theory contact terms to the masses of string states.Comment: 38 pages, Latex; v2: Comparison with string theory changed in light
of corrections to string theory results in hep-th/0206073 v3; state-operator
map modified; Physical interpretation and conclusions unchange
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