3,711 research outputs found
Concurrent -vector fields and energy beta-change
The present paper deals with an \emph{intrinsic} investigation of the notion
of a concurrent -vector field on the pullback bundle of a Finsler manifold
. The effect of the existence of a concurrent -vector field on some
important special Finsler spaces is studied. An intrinsic investigation of a
particular -change, namely the energy -change
($\widetilde{L}^{2}(x,y)=L^{2}(x,y)+ B^{2}(x,y) with \
B:=g(\bar{\zeta},\bar{\eta})\bar{\zeta} \pi\Gamma\widetilde{\Gamma}\beta$-change of the fundamental linear connection in Finsler geometry: the
Cartan connection, the Berwald connection, the Chern connection and the
Hashiguchi connection. Moreover, the change of their curvature tensors is
concluded.
It should be pointed out that the present work is formulated in a prospective
modern coordinate-free form.Comment: 27 pages, LaTex file, Some typographical errors corrected, Some
formulas simpifie
Detection and identification of Apple stem pitting virus and Apple stem grooving virus affecting apple and pear trees in Egypt
Apple stem pitting virus (ASPV) and Apple stem grooving virus (ASGV) are economically important and infect either individually or in mixed infection commercial apple and pear cultivars causing yield loses. Young green bud and/or base of petiole were collected from naturally infected apple and pear trees from different locations in Egypt. Both viruses were detected frequently in apple and pear samples. A total of 420 trees from 9 different orchards were tested using one-step RT-PCR; 13% and 17% of these samples were infected with ASPV and ASGV, respectively. Mixed infection with both viruses occurred in 4% of the tested trees. ELISA was reliable for detection of ASGV but not ASPV. Total RNA for one-step RT-PCR was isolated from 100 mg fresh affected apple and pear leaf tissue using Qiagen RNeasy plant mini-kit (Qiagen, Crawley, UK), according to the manufacturer’s instructions. The one step-RTPCR method was performed using ASPV and ASGV-specific primers for each virus. A 316 bp fragment for ASPV and 524bp fragment for ASGV were amplified and detected by gel electrophoresis analysis which indicated the presence of ASPV and ASGV in affected apple and pear cultivars. Southern blot hybridization of the amplified products to digoxigenin (DIG)-labeled cDNA probe for ASPV or ASGV confirmed the results obtained by electrophoresis analysis. No product was detected in amplified extracts of uninfected apple and pear samples. The detection of ASPV and ASGV by one step-RT-PCR assay was successful and appears useful for testing pome fruit germplasm in quarantine and budwood in certification programs.Keywords: Apple and pear, ASPV, ASGV, virus detection, One step RT-PCR, Southern blot hybridizatio
Improving the Representation and Conversion of Mathematical Formulae by Considering their Textual Context
Mathematical formulae represent complex semantic information in a concise
form. Especially in Science, Technology, Engineering, and Mathematics,
mathematical formulae are crucial to communicate information, e.g., in
scientific papers, and to perform computations using computer algebra systems.
Enabling computers to access the information encoded in mathematical formulae
requires machine-readable formats that can represent both the presentation and
content, i.e., the semantics, of formulae. Exchanging such information between
systems additionally requires conversion methods for mathematical
representation formats. We analyze how the semantic enrichment of formulae
improves the format conversion process and show that considering the textual
context of formulae reduces the error rate of such conversions. Our main
contributions are: (1) providing an openly available benchmark dataset for the
mathematical format conversion task consisting of a newly created test
collection, an extensive, manually curated gold standard and task-specific
evaluation metrics; (2) performing a quantitative evaluation of
state-of-the-art tools for mathematical format conversions; (3) presenting a
new approach that considers the textual context of formulae to reduce the error
rate for mathematical format conversions. Our benchmark dataset facilitates
future research on mathematical format conversions as well as research on many
problems in mathematical information retrieval. Because we annotated and linked
all components of formulae, e.g., identifiers, operators and other entities, to
Wikidata entries, the gold standard can, for instance, be used to train methods
for formula concept discovery and recognition. Such methods can then be applied
to improve mathematical information retrieval systems, e.g., for semantic
formula search, recommendation of mathematical content, or detection of
mathematical plagiarism.Comment: 10 pages, 4 figure
Magnetostrictive hysteresis of TbCo/CoFe multilayers and magnetic domains
Magnetic and magnetostrictive hysteresis loops of TbCo/CoFe multilayers under
field applied along the hard magnetization axis are studied using vectorial
magnetization measurements, optical deflectometry and magneto optical Kerr
microscopy. Even a very small angle misalignment between hard axis and magnetic
field direction is shown to drastically change the shape of magnetization and
magnetostrictive torsion hysteresis loops. Two kinds of magnetic domains are
revealed during the magnetization: big regions with opposite rotation of
spontaneous magnetization vector and spontaneous magnetic domains which appear
in a narrow field interval and provide an inversion of this rotation.
We show that the details of the hysteresis loops of our exchange-coupled
films can be described using the classical model of homogeneous magnetization
rotation of single uniaxial films and the configuration of observed domains.
The understanding of these features is crucial for applications (for MEMS or
microactuators) which benefit from the greatly enhanced sensitivity near the
point of magnetic saturation at the transverse applied field.Comment: 10 pages, 11 figure
Effect of nitric oxide donors on uterine and sub-endometrial blood flow in patients with unexplained infertility: a randomized controlled trial
Background: Impaired sub-endometrial perfusion might reduce endometrial receptivity and possibly contribute to unexplained infertility. A favorable effect on sub-endometrial blood flow has been demonstrated with nitric oxide.Methods: This randomized controlled trial evaluated the effect of nitroglycerine on uterine and sub-endometrial blood flow in women with unexplained infertility. Sixty women were randomized into 2 equal groups. The study group received 5mg nitroglycerine patch daily from day 2 of the cycle till the evaluation day and the control group received no treatment. Independent of the study arms, 30 parous women were included as the fertile group. Six to eight days after detecting luteinizing hormone surge, women were assessed for endometrial thickness, uterine artery blood flow with color Doppler and sub-endometrial blood flow with three-dimensional power Doppler.Results: Compared to fertile women, cases with unexplained infertility (control group) had a significantly thinner endometrium, higher uterine artery Doppler indices and lower sub-endometrial blood flow. Women who received nitroglycerin showed a significant improvement in sub-endometrial blood flow while uterine artery blood flow did not show a significant difference; however, the values were also comparable to fertile women. In addition, no effect on endometrial thickness was found with nitroglycerin treatment. Nitroglycerin treatment side effects were headache, blurring of vision and hypotension. These adverse effects were not significant compared to controls.Conclusions: In women with unexplained infertility, nitroglycerin significantly improved the sub-endometrial blood flow but did not affect the endometrial thickness
A Survey on Retrieval of Mathematical Knowledge
We present a short survey of the literature on indexing and retrieval of
mathematical knowledge, with pointers to 72 papers and tentative taxonomies of
both retrieval problems and recurring techniques.Comment: CICM 2015, 20 page
Recommended from our members
Transaction behaviour in large database environments: A methodological approach
This thesis presents the CITY benchmark, a database benchmark that fairly represents On-Line Transaction Processing (OLTP) environments. It analyses the most widely used benchmarks in general putting more emphasis on the Wisconsin benchmark and the Transaction Processing Council (TPC) benchmarks (TPC-A, TPC- B and TPC-C) in particular. It also presents an empirical approach to examine the workload of those benchmarks and discovered several technical limitations in their scripts. The thesis also presents an investigation of on-line transactions in large database environments. The tested environments were three of the largest organisations in the UK, those organisations were different in objectives and activities. The investigation identified on-line transaction behaviour and defined the salient characteristics of databases in high-volume transaction environments. The findings from those studies established the basis of a transaction and set of tables that are representative of them. The CITY benchmark design is directly driven from the findings from the empirical studies. The benchmark design took into consideration all the critiques directed towards the TPC benchmarks A, B and C. It is the first benchmark that is designed as a result of studying the behaviour of on-line transactions and databases in large database environments. The CITY benchmark is mainly designed to test and compare database systems performance in high-volume transaction environments (OLTP).
The work revealed the salient characteristics of large database environments and identified a typical behaviour of on-line transaction in OLTP environments. This research has clearly shown that the TPC benchmarks are not representative to the domain of high-volume transactions environments (OLTP) and it explained why they could be misleading if used to test database management systems in this domain. Additionally, this thesis presents a database performance evaluation methodology that is based on in-depth studies in large database environments
Some entanglement features of three-atoms Tavis-Cummings model: Cooperative case
In this paper we consider a system of identical three two-level atoms
interacting at resonance with a single-mode of the quantized field in a
lossless cavity. The initial cavity field is prepared in the coherent state
while the atoms are taken initially to be either in the uppermost excited state
"" or The -state or the -state. For this
system we investigate different kinds of atomic inversion and entanglement,
which arise between the different parts of the system due to the interaction.
Also the relationship, between entanglement and some other nonclassical effects
in the statistical properties, such as collapses and revivals in the atomic
inversion where superharmonic effects appear, is discussed. The -functions
for different cases are discussed. Most remarkably it is found that the
-state is more robust against energy losses, showing almost
coherent trapping and Schr\"odinger-cat states can not be produced from such
state. Also the entanglement of -state is more robust than the
-state. Another interesting feature found is that the state which
has no pairwise entanglement initially will have a much improvement of such
pairwise entanglement through the evolution. Sudden death and sudden revival of
atoms-pairwise entanglement are produced with the -state.Comment: 14 pages, 7 figure
Telleparallel Lagrange Geometry and a Unified Field Theory: Linearization of the Field Equations
The present paper is a natural continuation of our previous paper:
"Teleparallel Lagrange geometry and a unified field theory, Class. Quantum
Grav., 27 (2010), 045005 (29pp)" \cite{WNA}. In this paper, we apply a
linearization scheme on the field equations obtained in \cite{WNA}. Three
important results under the linearization assumption are accomplished. First,
the vertical fundamental geometric objects of the EAP-space loose their
dependence on the positional argument . Secondly, our linearized theory in
the Cartan-type case coincides with the GFT in the first order of
approximation. Finally, an approximate solution of the vertical field equations
is obtained.Comment: 18 pages, LaTeX fil
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