58 research outputs found
A Note on Lie-Lorentz Derivatives
The definition of ``Lie derivative'' of spinors with respect to Killing
vectors is extended to all kinds of Lorentz tensors. This Lie-Lorentz
derivative appears naturally in the commutator of two supersymmetry
transformations generated by Killing spinors and vanishes for Vielbeins. It can
be identified as the generator of the action of isometries on supergravity
fields and its use for the calculation of supersymmetry algebras is revised and
extended.Comment: Latex2e, 9 pages, AMS font
Weak-Field Gravity of Revolving Circular Cosmic Strings
A weak-field solution of Einstein's equations is constructed. It is generated
by a circular cosmic string revolving in its plane about the centre of the
circle. (The revolution is introduced to prevent the string from collapsing.)
This solution exhibits a conical singularity, and the corresponding deficit
angle is the same as for a straight string of the same linear energy density,
irrespective of the angular velocity of the string.Comment: 13 pages, LaTe
Maxwell's theory on a post-Riemannian spacetime and the equivalence principle
The form of Maxwell's theory is well known in the framework of general
relativity, a fact that is related to the applicability of the principle of
equivalence to electromagnetic phenomena. We pose the question whether this
form changes if torsion and/or nonmetricity fields are allowed for in
spacetime. Starting from the conservation laws of electric charge and magnetic
flux, we recognize that the Maxwell equations themselves remain the same, but
the constitutive law must depend on the metric and, additionally, may depend on
quantities related to torsion and/or nonmetricity. We illustrate our results by
putting an electric charge on top of a spherically symmetric exact solution of
the metric-affine gauge theory of gravity (comprising torsion and
nonmetricity). All this is compared to the recent results of Vandyck.Comment: 9 pages, REVTeX, no figures; minor changes, version to be published
in Class. Quantum Gra
Coherent methods in the X-ray sciences
X-ray sources are developing rapidly and their coherent output is growing
extremely rapidly. The increased coherent flux from modern X-ray sources is
being matched with an associated rapid development in experimental methods.
This article reviews the literature describing the ideas that utilise the
increased brilliance from modern X-ray sources. It explores how ideas in
coherent X-ray science are leading to developments in other areas, and vice
versa. The article describes measurements of coherence properties and uses this
discussion as a base from which to describe partially-coherent diffraction and
X-ray phase contrast imaging, with its applications in materials science,
engineering and medicine. Coherent diffraction imaging methods are reviewed
along with associated experiments in materials science. Proposals for
experiments to be performed with the new X-ray free-electron-lasers are briefly
discussed. The literature on X-ray photon correlation spectroscopy is described
and the features it has in common with other coherent X-ray methods are
identified. Many of the ideas used in the coherent X-ray literature have their
origins in the optical and electron communities and these connections are
explored. A review of the areas in which ideas from coherent X-ray methods are
contributing to methods for the neutron, electron and optical communities is
presented.Comment: A review articel accepted by Advances in Physics. 158 pages, 29
figures, 3 table
Sequence of the HAP3 transcription factor of Kluyveromyces lactis predicts the presence of a novel 4-cysteine zinc-finger motif
The Sequence of An 8.8-kb Segment On the Left Arm of Chromosome-ii From Saccharomyces-cerevisiae Reveals 4 New Open Reading Frames Including Homologs of Animal Dna-polymerase Alpha-primases and Bacterial Gtp Cyclohydrolase-ii
The DNA sequence of two contiguous 7648 bp and 1194 bp BamHI fragments from the cosmid alpha 1201 located about 60 kb from the centromere on the left arm of chromosome II from Saccharomyces cerevisiae has been determined. Sequence analysis reveals four new open reading frames longer than 300 bp: YBL0415 (309 bp), YBL0416(4539 bp), YBL0417 (1035 bp) and YBL0414 (2115 bp), which extends into the neighbouring 5.2 kb BamHI fragment. The YBL0414 shows homologies to the mouse 68 kDa and Drosophila melanogaster 76 kDa subunits of the DNA polymerase alpha-primase complex. The YBL0417 is homologous to bacterial GTP cyclohydrolase II (EC 3.5.4.25). The sequence has been deposited in the EMBC data library under Accession Number X74738
Climate change, air pollution and human health
This article takes stock of recent literature on health impacts of climate change and air pollution, and the corresponding health benefits of policy action aiming to reduce greenhouse gas and air pollutant emissions. We focus particularly on the publications in the Focus Collection on âClimate Change, Air Pollution and Human Healthâ, which illustrate advances in three key research areas. First, the impacts of global warming and air pollution are unevenly distributed, as they disproportionately affect vulnerable socio-economic groups including older adults, pregnant women, children, and people with lower earnings or education levels. Second, recent research improves our understanding and quantification of impacts identified in earlier work, and explores novel impact pathways such as the associations between allergies and climate change, and between air pollution and diabetes mellitus, Alzheimerâs disease and Parkinsonâs disease. Third, significant synergies in tackling climate change and air pollution can strengthen the case for ambitious policy action. These synergies are heterogeneous across sectors and regions, point to low-hanging fruit among policy options (e.g. phasing out coal), and provide a strong basis for broader sustainable development, improving health and gender equality. Finally, we point out suggestions for future research. Research advances can guide policies to mitigate future climate change, air pollution and the associated health impacts, while informing adaptation strategies that aim to protect the health of the most vulnerable in society
Regulation of the Expression of the H+-atpase Genes Pma1 and Pma2 During Growth and Effects of Octanoic-acid in Saccharomyces-cerevisiae
A peak of plasma membrane H+-ATPase activity during exponential growth is correlated with the expression of the PMA1 gene as monitored by measurements of the beta-galactosidase activity from a PMA1-lacZ fusion. This peak of activity is also correlated to the content of the H+-ATPase protein in yeast plasma membrane as shown by quantitative immunodetection. The PMA(2)-lacZ fusion assay indicates that the expression of the PMA2 gene is activated somewhat later during exponential phase but under all circumstances its activity remains at least 500-fold lower than that of the PMA1-lacZ fusion. A slight but significant stimulation of ATPase activity by low concentrations of octanoic acid coincides with a decrease in the PMA1 gene expression. It is concluded that octanoic acid stimulates de PMA1 ATPase activity by posttranslational mechanisms
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