Effects of Linear Deformation on Relaxation Time and Some Fermi Properties of Metals

In this work, a model for computing the relaxation time, Fermi velocity and Fermi temperature of deformed metals was developed based on free electron theory. This study generalized the work of Kiejna and Pogosov (2000) due to the shortcomings of the electron density parameter of deformed metals. They failed to account for metal dilation by assuming a constant value for the Poisson ratio of metals which leads to neglect of the uniaxial strain (deformation) in their computation. This causes the electron density parameter of both deformed and undeformed metals to be equal. The result obtained in this work revealed that there is an agreement between the experimental and computed values of the Fermi velocity, Fermi temperature and relaxation time of some of the metals calculated which shows the validity of the model used in the study. The experimental value used in this work is theoretically obtained by substituting the experimental value of Fermi energy obtained from solid state Physics by Charles Kittel (1976) into the model used in the computation. The Fermi velocity, Fermi temperature and relaxation time of all the metals subjected to different deformation decreases as deformation increases. This seems to suggest that as deformation increases the collision frequency between the interacting electron decreases which forces the relaxation time, Fermi velocity and Fermi temperature to decrease as deformation increases. This behavior could also be due to an increase in the inter-atomic spacing between the interacting electrons in the metals during deformation which reduces the strength of interaction between the electrons in metal and their-by forces the relaxation time, Fermi velocity and Fermi temperature to decrease as deformation increases. Keywords: relaxation time, Fermi velocity, Fermi temperature, mean free path, deformation, Fermi surface DOI: 10.7176/JNSR/9-8-04 Publication date: April 30th 201

Quantitative variation for apomictic reproduction in the genus Boechera (Brassicaceae)

• Premise of the study: The evolution of asexual seed production (apomixis) from sexual relatives is a great enigma of plant biology. The genus Boechera is ideal for studying apomixis because of its close relation to Arabidopsis and the occurrence of sexual and apomictic species at low ploidy levels (diploid and triploid). Apomixis is characterized by three components: unreduced embryo-sac formation (apomeiosis), fertilization-independent embryogenesis (parthenogenesis), and functional endosperm formation (pseudogamy or autonomous endosperm formation). Understanding the variation in these traits within and between species has been hindered by the laborious histological analyses required to analyze large numbers of samples. • Methods: To quantify variability for the different components of apomictic seed development, we developed a high-throughput flow cytometric seed screen technique to measure embryo:endosperm ploidy in over 22000 single seeds derived from 71 accessions of diploid and triploid Boechera. • Key results: Three interrelated features were identified within and among Boechera species: (1) variation for most traits associated with apomictic seed formation, (2) three levels of apomeiosis expression (low, high, obligate), and (3) correlations between apomeiosis and parthenogenesis/pseudogamy. • Conclusions: The data presented here provide a framework for choosing specific genotypes for correlations with large "omics" data sets being collected for Boechera to study population structure, gene flow, and evolution of specific traits. We hypothesize that low levels of apomeiosis represent an ancestral condition of Boechera, whereas high apomeiosis levels may have been induced by global gene regulatory changes associated with hybridization

Hepatitis B surface antigenaemia and risk factors of transmission among apparently healthy students of University of Ilorin, Ilorin-Nigeria

This study aimed at determining the prevalence of Hepatitis B surface antigenaemia among first year students of University of Ilorin, Ilorin Nigeria. A total of 200 students (119 males and 81 females: ages 16 to 40 years), who consented voluntarily after thorough explanation of the purpose of the study, were selected. The sera of the participants were tested for the presence of HBsAg by parallel diagnostic method using Diaspot® HBsAg test kit and Smart CheckTM HBsAg device. Of the 200 samples tested, 18 (9.0%) were HBsAg positive. The result also showed that 13 (10.9%) out of the 119 males were positive, while 5 (6.2%) out of the 81 females were positive. Analysis of the results by age groups showed that subjects ≤20 years had a prevalence of 9.8%, subjects of age range 21-30 years had a prevalence of 8.1% while subjects of age range 31-40 years had zero prevalence. Analysis of the results according to the risk factors of transmission showed that subjects who reported circumcision only had a prevalence of 7.4%, while subjects who reported history of medical operation and blood transfusion had a prevalence of 10.0%. Among subjects who reported HBV vaccination only, prevalence of 8.3% was recorded, while 12.5% prevalence was recorded for subjects who reported a combination of circumcision, medical operation and blood transfusion. This study however confirmed the presence of Hepatitis B surface antigenaemia among apparently healthy first year students of the University of Ilorin. General surveillance, mass immunization and public health education to stop the spread of the infection on campus and indeed the whole society is advocated.Key words: Prevalence, HBsAg, antigenaemia, student

On the origin and evolution of apomixis in Boechera

The genetic mechanisms causing seed development by gametophytic apomixis in plants are predominantly unknown. As apomixis is consistently associated with hybridity and polyploidy, these confounding factors may either (a) be the underlying mechanism for the expression of apomixis, or (b) obscure the genetic factors which cause apomixis. To distinguish between these hypotheses, we analyzed the population genetic patterns of diploid and triploid apomictic lineages and their sexual progenitors in the genus Boechera (Brassicaceae). We find that while triploid apomixis is associated with hybridization, the majority of diploid apomictic lineages are likely the product of intra-specific crosses. We then show that these diploid apomicts are more likely to sire triploid apomictic lineages than conspecific sexuals. Combined with flow cytometric seed screen phenotyping for male and female components of apomixis, our analyses demonstrate that hybridization is an indirect correlate of apomixis in Boechera