Towards a mathematical system for extension education - II

A brief description is given of a mathematical model for use in extension education regarding fisheries in developing countries

Thermoinhibition of seed germination

Thermoinhibition describes the inability of seeds to germinate at high temperatures, although germination proceeds immediately when the temperature is reduced below a certain threshold level. This phenomenon is distinct from thermodormancy, where some form of dormancy-breaking treatment is required before germination can proceed at the favourable temperature. Like seed dormancy, thermoinhibition is manifested in a number of different ways, ranging from simple high-temperature induced changes to the structures enclosing the embryo which prevent radicle emergence, to the interaction of a number of different factors, and probable expression of certain genes inhibitory to germination which may be temperature regulated. Thermoinhibition occurs in a large number of important crop species, so that an understanding of this phenomenon is both of scientific interest and practical importance

Evaluating the most promising sites for wind energy development in Arizona USA: Working paper series--05-09

During the summer of 2003, the state of Arizona took delivery of a set of high-resolution wind energy maps. After applying various exclusions, the developable wind energy potential is 23,290 MW of class 3 or higher, 2,630 MW of class 4 or higher, and 775 MW of class 5 or higher winds. Having determined the potential wind resource, the geographical information system data supplied with the wind maps was used to create a wind resource inventory and to systematically identify the most promising sites for wind energy development. In addition to wind energy potential, proximity to transmission lines and roads, and land ownership were considered in this analysis. Following that, the cost of energy was estimated at a few geographically diverse sites, including class 3, 4, and 5 wind resource areas, at a hub height of 70 m. These estimates revealed that the real levelized cost of energy in 2005 dollars ranged from 4.21 to 5.04 cents per kWh, as the wind class varies from 5 to 3. This paper documents the findings of the wind mapping process, describes the method and results of evaluating the most promising sites for wind development, and presents the cost of energy results

Possible Dibaryons with Strangeness s=-5

In the framework of $RGM$, the binding energy of the six quark system with strangeness s=-5 is systematically investigated under the SU(3) chiral constituent quark model. The single $\Xi^*\Omega$ channel calculation with spins S=0 and 3 and the coupled $\Xi\Omega$ and $\Xi^*\Omega$ channel calculation with spins S=1 and 2 are considered, respectively. The results show following observations: In the spin=0 case, $\Xi^* \Omega$ is a bound dibaryon with the binding energy being $80.0 \sim 92.4 MeV$. In the S=1 case, $\Xi\Omega$ is also a bound dibaryon. Its binding energy is ranged from $26.2 MeV$ to $32.9 MeV$. In the S=2 and S=3 cases, no evidence of bound dibaryons are found. The phase shifts and scattering lengths in the S=0 and S=1 cases are also given.Comment: 10 pages, late

A role for tetraspanin proteins in regulating fusion induced by Burkholderia thailandensis

Burkholderia pseudomallei is the causative agent of melioidosis, a disease with high morbidity that is endemic in South East Asia and northern Australia. An unusual feature of the bacterium is its ability to induce multinucleated giant cell formation (MNGC), which appears to be related to bacterial pathogenicity. The mechanism of MNGC formation is not fully understood, but host cell factors as well as known bacterial virulence determinants are likely to contribute. Since members of the tetraspanin family of membrane proteins are involved in various types of cell:cell fusion, their role in MNGC formation induced by Burkholderia thailandensis, a mildly pathogenic species closely related to B. pseudomallei, was investigated. The effect of antibodies to tetraspanins CD9, CD81, and CD63 in MNGC formation induced by B. thailandensis in infected mouse J774.2 and RAW macrophage cell lines was assessed along with that of recombinant proteins corresponding to the large extracellular domain (EC2) of the tetraspanins. B. thailandensis-induced fusion was also examined in macrophages derived from CD9 null and corresponding WT mice, and in J774.2 macrophages over-expressing CD9. Antibodies to CD9 and CD81 promoted MNGC formation induced by B. thailandensis, whereas EC2 proteins of CD9, CD81, and CD63 inhibited MNGC formation. Enhanced MNGC formation was observed in CD9 null macrophages, whereas a decrease in MNGC formation was associated with overexpression of CD9. Overall our findings show that tetraspanins are involved in MNGC formation induced by B. thailandensis and by implication, B. pseudomallei, with CD9 and CD81 acting as negative regulators of this process

The effect of boundary conditions on resonant ultrasonic spherical chains

The response of a resonant chain of spheres to changes in holder material and pre-compression is studied at ultrasonic frequencies. The system is found to be very sensitive to these parameters, with the creation of impulsive waveforms from a narrow bandwidth input seen only for certain chain lengths and holder materials. In addition, careful experiments were performed using known amounts of pre-compression force, using a calibrated stylus arrangement. At negligible pre-compression levels, impulses were generated within the chain, which were then suppressed by increased pre-compression. This was accompanied by large changes in propagation velocity as the system gradually changes from being strongly nonlinear to being more linear. Simulations using a discrete model for the motion of each sphere agree well with experimental data

T-cell responses against rhinovirus species A and C in asthmatic and healthy children

Background Infections by rhinovirus (RV) species A and C are the most common causes of exacerbations of asthma and a major cause of exacerbations of other acute and chronic respiratory diseases. Infections by both species are prevalent in pre-school and school-aged children and, particularly for RV-C, can cause severe symptoms and a need for hospitalization. While associations between RV infection and asthma are well established, the adaptive immune-mechanisms by which RV infections influence asthma exacerbations are yet to be defined. Objective The aim of this study was to characterize and compare T-cell responses between RV-A and RV-C and to test the hypothesis that T-cell responses would differ between asthmatic children and healthy controls. Methods A multi-parameter flow cytometry assay was used to characterize the in vitro recall T-cell response against RV-A and RV-C in PBMCs from children with acute asthma (n = 22) and controls (n = 26). The responses were induced by pools of peptides containing species-specific VP1 epitopes of RV-A and RV-C. Results Regardless of children's clinical status, all children that responded to the in vitro stimulation (>90%) had a similar magnitude of CD4+ T-cell responses to RV-A and RV-C. However, asthmatic children had a significantly lower number of circulating regulatory T cells (Tregs), and healthy controls had significantly more Tregs induced by RV-A than RV-C. Conclusions and Clinical Relevance The comparable recall memory T-cell responses in asthmatic and control children to both RV-A and RV-C show that differences in the antibody and inflammatory responses previously described are likely to be due to regulation, with a demonstrated candidate being reduced regulatory T-cells. The reduced Treg numbers demonstrated here could explain the asthmatic's inability to appropriately control immunopathological responses to RV infections

The implications of the regional haze rule on renewable and wind energy development on Native American lands in the west: Working paper series--02-21

A study conducted at Northern Arizona University investigated the barriers and opportunities facing Native American tribes in the west when considering development of their renewable energy resources in order to reduce regional haze. This paper summarizes some of the findings of that work with special attention to wind energy. Background information is presented concerning the regional haze rule and the western regional air partnership, and some of the circumstances surrounding development of tribal energy resources. An assessment of tribal energy issues revealed that many Native American tribes are interested in developing their renewable resources. However, this development should occur within the context of maintaining and strengthening their cultural, social, economic, and political integrity. Furthermore, it is shown that Native American lands possess an abundant wind resource. A list of potential actions in which tribes may participate prior to or during development of their wind or renewable resources is provided

On Using High-Definition Body Worn Cameras for Face Recognition from a Distance

Recognition of human faces from a distance is highly desirable for law-enforcement. This paper evaluates the use of low-cost, high-definition (HD) body worn video cameras for face recognition from a distance. A comparison of HD vs. Standard-definition (SD) video for face recognition from a distance is presented. HD and SD videos of 20 subjects were acquired in different conditions and at varying distances. The evaluation uses three benchmark algorithms: Eigenfaces, Fisherfaces and Wavelet Transforms. The study indicates when gallery and probe images consist of faces captured from a distance, HD video result in better recognition accuracy, compared to SD video. This scenario resembles real-life conditions of video surveillance and law-enforcement activities. However, at a close range, face data obtained from SD video result in similar, if not better recognition accuracy than using HD face data of the same range