Effects of random localizing events on matter waves: formalism and examples

A formalism is introduced to describe a number of physical processes that may break down the coherence of a matter wave over a characteristic length scale l. In a second-quantized description, an appropriate master equation for a set of bosonic "modes" (such as atoms in a lattice, in a tight-binding approximation) is derived. Two kinds of "localizing processes" are discussed in some detail and shown to lead to master equations of this general form: spontaneous emission (more precisely, light scattering), and modulation by external random potentials. Some of the dynamical consequences of these processes are considered: in particular, it is shown that they generically lead to a damping of the motion of the matter-wave currents, and may also cause a "flattening" of the density distribution of a trapped condensate at rest.Comment: v3; a few corrections, especially in Sections IV and

Towards an HH-theorem for granular gases

The $H$-theorem, originally derived at the level of Boltzmann non-linear kinetic equation for a dilute gas undergoing elastic collisions, strongly constrains the velocity distribution of the gas to evolve irreversibly towards equilibrium. As such, the theorem could not be generalized to account for dissipative systems: the conservative nature of collisions is an essential ingredient in the standard derivation. For a dissipative gas of grains, we construct here a simple functional $\mathcal H$ related to the original $H$, that can be qualified as a Lyapunov functional. It is positive, and results backed by three independent simulation approaches (a deterministic spectral method, the stochastic Direct Simulation Monte Carlo technique, and Molecular Dynamics) indicate that it is also non-increasing. Both driven and unforced cases are investigated

Production of Polyclonal Antibodies Against a Yam Isolate of Cucumber Mosaic Virus (Cmv).

Cucumber mosaic virus (CMV) genus Cucumovirus was recently detected in yam in Ghana, Togo and Benin bringing to six the total number of countries reporting CMV infection in yam worldwide. Two serotypes of CMV are distinguished and a specific antibody against the yam isolate of CMV is currently not available. Rabbit polyclonal antibodies were produced against purified preparations of a yam isolate of CMV from Nigeria. The antibody titre was determined by Protein-A sandwich (PAS) enzymelinked immunosorbent assay (ELISA) and antigen-coated plate (ACP) ELISA. Antigen detection limit of the antibody was determined by PAS-ELISA using serial dilutions of infected sap. The CMV antiserum produced had a titre of 1:25,600 and 1:64,000 by PAS- and ACP-ELISA, respectively and a sap dilution end point of 1:160. The antibody detected homologous antigen in infected yam leaves from Ghana, Togo, Benin and Nigeria. The CMV polyclonal antibody produced in this study will enhance CMV monitoring and contribute to prevention of the spread of CMV infection which is spreading in yamCucumber mosaic virus (CMV) genus Cucumovirus was recently detected in yam in Ghana, Togo and Benin bringing to six the total number of countries reporting CMV infection in yam worldwide. Two serotypes of CMV are distinguished and a specific antibody against the yam isolate of CMV is currently not available. Rabbit polyclonal antibodies were produced against purified preparations of a yam isolate of CMV from Nigeria. The antibody titre was determined by Protein-A sandwich (PAS) enzymelinked immunosorbent assay (ELISA) and antigen-coated plate (ACP) ELISA. Antigen detection limit of the antibody was determined by PAS-ELISA using serial dilutions of infected sap. The CMV antiserum produced had a titre of 1:25,600 and 1:64,000 by PAS- and ACP-ELISA, respectively and a sap dilution end point of 1:160. The antibody detected homologous antigen in infected yam leaves from Ghana, Togo, Benin and Nigeria. The CMV polyclonal antibody produced in this study will enhance CMV monitoring and contribute to prevention of the spread of CMV infection which is spreading in ya

Children's construction task performance and spatial ability: controlling task complexity and predicting mathematics performance.

This paper presents a methodology to control construction task complexity and examined the relationships between construction performance and spatial and mathematical abilities in children. The study included three groups of children (N = 96); ages 7-8, 10-11, and 13-14 years. Each group constructed seven pre-specified objects. The study replicated and extended previous findings that indicated that the extent of component symmetry and variety, and the number of components for each object and available for selection, significantly predicted construction task difficulty. Results showed that this methodology is a valid and reliable technique for assessing and predicting construction play task difficulty. Furthermore, construction play performance predicted mathematical attainment independently of spatial ability

Production of Polyclonal Antibody Against an Isolate of Yam-infecting Badnavirus from Nigeria

Integrated viral sequences and high sequence variability among badnaviruses complicates the development of specific reliable molecular detection tests for yam-infecting badnaviruses. Thus Serological techniques are of notable importance for routine testing and monitoring of these viruses. The major limiting factor to the use of serological techniques is the limited availability of antibodies. Rabbit polyclonal antibody was produced against a purified preparation of a yam-infecting badnavirus from Nigeria. Antibody titre was determined by Protein-A sandwich (PAS) enzyme-linked immunosorbent assay (ELISA). The antibody produced had a titre of 1:1280 in PAS-ELISA and detected yam-infecting badnaviruses in infected yam leaves from Nigeria, Ghana, Benin and Togo. The suitability of the antibody for use in immunocapture polymerase chain reaction (IC-PCR) was evaluated. The antibody successfully trapped both Dioscorea alata bacilliform virus (DaBV) and Dioscorea sansibarensis bacilliform virus (DsBV) for IC-PCR detection. The antibody produced in this study will enhance certification of yam planting materials across West Africa and also facilitate the safe international movement of yam germplasm

Production of yam mosaic virus monoclonal antibodies in mice peritoneum

Yam mosaic virus (YMV) is one of the most economically important virus infecting yams. Immunoassays are routinely used for laboratory diagnosis of YMV and for certification of planting materials. However, YMV antibodies, the key reagents, needed for these immunoassays are not readily available. We describe in this paper, the production of YMV monoclonal antibodies for the detection of YMV. The monoclonal antibody was produced by immunizing six weeks old BALB/c mice with YMV hybridoma cells and tapping soft peritoneal tumor tissues for antibody. Antibody titre was determined by triple antibody sandwich-enzyme-linked immunosorbent assay (TAS-ELISA) using YMV infected yam leaves and non-infected tissue culture yam leaves. The antibody produced had a titre of 1:1,310,720 and an optimal TAS-ELISA detection dilution of 1:80,000. This high-titre YMV monoclonal antibody is useful for monitoring and certification purposes

Back Reaction and Graceful Exit in String Inflationary Cosmology

Classical string cosmology consists of two branches related to each other by scale-factor duality: a super-inflation branch and a Friedmann-Robertson-Walker (FRW) branch. Curvature and string coupling singularity separates the two branches, hence posing `graceful exit problem' to super-inflationary string cosmology. In an exactly soluble two-dimensional compactification model it is shown that quantum back reaction retards curvature and string coupling growth and connects the super-inflation branch to the FRW branch without encountering a singularity. This may offer an attractive solution to the `graceful exit problem' in string inflationary cosmology.Comment: 12 pages, ReVTe

Variable stars in the Open Cluster M11 (NGC 6705)

V-band time-series CCD photometric observations of the intermediate-age open cluster M11 were performed to search for variable stars. Using these time-series data, we carefully examined light variations of all stars in the observing field. A total of 82 variable stars were discovered, of which 39 stars had been detected recently by Hargis et al. (2005). On the basis of observational properties such as variable period, light curve shape, and position on a color-magnitude diagram, we classified their variable types as 11 delta Scuti-type pulsating stars, 2 gamma Doradus-type pulsating stars, 40 W UMa-type contact eclipsing binaries, 13 Algol-type detached eclipsing binaries, and 16 eclipsing binaries with long period. Cluster membership for each variable star was deduced from the previous proper motion results (McNamara et al. 1977) and position on the color-magnitude diagram. Many pulsating stars and eclipsing binaries in the region of M11 are probable members of the cluster.Comment: 23 pages, 9 figures, 3 tables, and accepted for publication in PAS

Re-Evaluation of Yam Mosaic Virus (YMV) Detection Methods

Accurate and timely detection is vital for mitigation of tuber yield losses resulting from yam mosaic virus (YMV) infection on yam, a major food security crop in West Africa. The observation, from our previous studies, that the triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA), the most commonly used detection method for YMV, detected the virus in significantly less leaf samples than immunocapture reverse transcription polymerase chain reaction (IC-RT-PCR) necessitated a re-evaluation of YMV detection methods. In the present study, eighteen previously tested YMV positive leaf samples from Benin and Ghana were re-tested using TAS-ELISA, Protein A-sandwich (PAS) ELISA and IC-RT-PCR. Three sap dilutions, 1/10, 1/50 and 1/100, were tested for each sample. Both at 1/10 and 1/50 dilutions, PAS-ELISA and IC-RT-PCR detected YMV in 11 (61.1%) and 12 (66.7%) of the leaves respectively. Virus detection by PAS-ELISA reduced to 50% at 1/100 sap dilution and increased to 77.8% in IC-RT-PCR. YMV detection by TAS-ELISA varied between 38.9% and 16.7% at 1/10 and 1/100 dilutions respectively. These results indicate a deficiency in the use of TAS-ELISA as a sole YMV certification method since the detecting monoclonal antibody used in this assay may be strain specific. The use of PAS-ELISA at a 1/10 sap dilution is suggested for YMV detection where the facilities for molecular detection are unavailabl