4,344 research outputs found
Development of National Assessment Criteria for Green Schools in China
In the Peoples' Republic of China, a green schools programme was initiated in 1996. It has promoted both education reform and socially sustainable development. Recently, the assessment criteria for green schools have become an obstacle to the rapid development of the green school initiative, mainly due to the cultural and social system in Mainland China. Because there are many district criteria which mainly focus on green schools construction and evaluation, it is necessary to have new criteria to replace them. However, the requirements of the existing national criteria aren’t detailed, and the requirements don’t satisfy evaluation needs after the provincial criteria are replaced. Hence, the new national criteria should include a more comprehensive set of indices and requirements. This paper firstly examines the experiences from other countries and areas, and then analyses weaknesses of the existing green schools assessment process in China. Finally, some  understanding about green schools, and principles to establish new national criteria in China, are discussed in the paper. Since new national criteria are being established, they will be applied to the evaluation of the national green schools project in Mainland China in 2006
A Cosmology-Independent Calibration of Gamma-Ray Burst Luminosity Relations and the Hubble Diagram
An important concern in the application of gamma-ray bursts (GRBs) to
cosmology is that the calibration of GRB luminosity/energy relations depends on
the cosmological model, due to the lack of a sufficient low-redshift GRB
sample. In this paper, we present a new method to calibrate GRB relations in a
cosmology-independent way. Since objects at the same redshift should have the
same luminosity distance and since the distance moduli of Type Ia supernovae
(SNe Ia) obtained directly from observations are completely cosmology
independent, we obtain the distance modulus of a GRB at a given redshift by
interpolating from the Hubble diagram of SNe Ia. Then we calibrate seven GRB
relations without assuming a particular cosmological model and construct a GRB
Hubble diagram to constrain cosmological parameters. From the 42 GRBs at
, we obtain ,
for the flat CDM model, and
for the dark energy model with a constant equation of state
, which is consistent with the concordance model in
a 1- confidence region.Comment: 7 pages, 3 figures, 1 table, now matches the editorially revised
version; accepted for publication in ApJ (vol 685)
Changes in the measured image separation of the gravitational lens system, PKS 1830-211
We present eight epochs of 43 GHz, dual-polarisation VLBA observations of the
gravitational lens system PKS 1830-211, made over fourteen weeks. A bright,
compact ``core'' and a faint extended ``jet'' are clearly seen in maps of both
lensed images at all eight epochs.
The relative separation of the radio centroid of the cores (as measured on
the sky) changes by up to 87 micro arcsec between subsequent epochs.
A comparison with the previous 43 GHz VLBA observations (Garrett et al. 1997)
made 8 months earlier show even larger deviations in the separation of up to
201 micro arcsec. The measured changes are most likely produced by changes in
the brightness distribution of the background source, enhanced by the
magnification of the lens. A relative magnification matrix that is applicable
on the milliarcsecond scale has been determined by relating two vectors (the
``core-jet'' separations and the offsets of the polarised and total intensity
emission) in the two lensed images. The determinant of this matrix,
-1.13 +/-0.61, is in good agreement with the measured flux density ratio of
the two images. The matrix predicts that the 10 mas long jet, that is clearly
seen in previous 15 and 8.4 GHz VLBA observations (Garrett et al. 1997,
Guirado et al. 1999), should correspond to a 4 mas long jet trailing to the
south-east of the SW image. The clear non-detection of this trailing jet is a
strong evidence for sub-structure in the lens and may require more realistic
lens models to be invoked, e.g. Nair & Garrett (2000).Comment: 8 pages, 5 figure
Magic wavelengths for the np-ns transitions in alkali-metal atoms
Extensive calculations of the electric-dipole matrix elements in alkali-metal
atoms are conducted using the relativistic all-order method. This approach is a
linearized version of the coupled-cluster method, which sums infinite sets of
many-body perturbation theory terms. All allowed transitions between the lowest
ns, np_1/2, np_3/2 states and a large number of excited states are considered
in these calculations and their accuracy is evaluated. The resulting
electric-dipole matrix elements are used for the high-precision calculation of
frequency-dependent polarizabilities of the excited states of alkali-metal
atoms. We find magic wavelengths in alkali-metal atoms for which the ns and
np_1/2 and np_3/2 atomic levels have the same ac Stark shifts, which
facilitates state-insensitive optical cooling and trapping.Comment: 12 pages, 8 figure
Anisotropic charge transport in non-polar GaN QW: polarization induced charge and interface roughness scattering
Charge transport in GaN quantum well (QW) devices grown in non-polar
direction has been theoretically investigated . Emergence of anisotropic line
charge scattering mechanism originating as a result of anisotropic rough
surface morphology in conjunction with in-plane built-in polarization has been
proposed. It has shown that in-plane growth anisotropy leads to large
anisotropic carrier transport at low temperatures. At high temperatures, this
anisotropy in charge transport is partially washed out by strong isotropic
optical phonon scattering in GaN QW.Comment: 4 pages, 4 figure
Charge localization at the interface between La1-xSrxMnO3 and the infinite layers cuprate CaCuO2
(CaCuO2)m/(La0.7Sr0.3MnO3)n superlattices, consisting of the infinite layers
cuprate CaCuO2 and the optimally doped manganite La1-xSrxMnO3, were grown by
pulsed laser deposition. The transport properties are dominated by the
manganite block. X-Ray Absorption spectroscopy measurements show a clear
evidence of an orbital reconstruction at the interface, ascribed to the
hybridization between the Cu 3d3z2-r2 and the Mn 3d3z2-r2 orbitals via
interface apical oxygen ions. Such a mechanism localizes holes at the
interfaces, thus preventing charge transfer to the CaCuO2 block. Some charge
(holes) transfer occurs toward the La0.7Sr0.3MnO3 block in strongly oxidized
superlattices, contributing to the suppression of the magnetotransport
properties.Comment: 20 pages, 6 figure
On the Solution to the "Frozen Star" Paradox, Nature of Astrophysical Black Holes, non-Existence of Gravitational Singularity in the Physical Universe and Applicability of the Birkhoff's Theorem
Oppenheimer and Snyder found in 1939 that gravitational collapse in vacuum
produces a "frozen star", i.e., the collapsing matter only asymptotically
approaches the gravitational radius (event horizon) of the mass, but never
crosses it within a finite time for an external observer. Based upon our recent
publication on the problem of gravitational collapse in the physical universe
for an external observer, the following results are reported here: (1) Matter
can indeed fall across the event horizon within a finite time and thus BHs,
rather than "frozen stars", are formed in gravitational collapse in the
physical universe. (2) Matter fallen into an astrophysical black hole can never
arrive at the exact center; the exact interior distribution of matter depends
upon the history of the collapse process. Therefore gravitational singularity
does not exist in the physical universe. (3) The metric at any radius is
determined by the global distribution of matter, i.e., not only by the matter
inside the given radius, even in a spherically symmetric and pressureless
gravitational system. This is qualitatively different from the Newtonian
gravity and the common (mis)understanding of the Birkhoff's Theorem. This
result does not contract the "Lemaitre-Tolman-Bondi" solution for an external
observer.Comment: 8 pages, 4 figures, invited plenary talk at "The first Galileo-Xu
Guangqi conference", Shanghai, China, 2009. To appear in International
Journal of Modern Physics D (2010
Calibration of GRB Luminosity Relations with Cosmography
For the use of Gamma-Ray Bursts (GRBs) to probe cosmology in a
cosmology-independent way, a new method has been proposed to obtain luminosity
distances of GRBs by interpolating directly from the Hubble diagram of SNe Ia,
and then calibrating GRB relations at high redshift. In this paper, following
the basic assumption in the interpolation method that objects at the same
redshift should have the same luminosity distance, we propose another approach
to calibrate GRB luminosity relations with cosmographic fitting directly from
SN Ia data. In cosmography, there is a well-known fitting formula which can
reflect the Hubble relation between luminosity distance and redshift with
cosmographic parameters which can be fitted from observation data. Using the
Cosmographic fitting results from the Union set of SNe Ia, we calibrate five
GRB relations using GRB sample at and deduce distance moduli of GRBs
at by generalizing above calibrated relations at high
redshift. Finally, we constrain the dark energy parameterization models of the
Chevallier-Polarski-Linder (CPL) model, the Jassal-Bagla-Padmanabhan (JBP)
model and the Alam model with GRB data at high redshift, as well as with the
Cosmic Microwave Background radiation (CMB) and the baryonic acoustic
oscillation (BAO) observations, and we find the CDM model is
consistent with the current data in 1- confidence region.Comment: 15 pages, 4 figures, 2 tables; accepted for publication in IJMP
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