Decoupling method for dynamical mean field theory calculations

In this paper we explore the use of an equation of motion decoupling method as an impurity solver to be used in conjunction with the dynamical mean field self-consistency condition for the solution of lattice models. We benchmark the impurity solver against exact diagonalization, and apply the method to study the infinite $U$ Hubbard model, the periodic Anderson model and the $pd$ model. This simple and numerically efficient approach yields the spectra expected for strongly correlated materials, with a quasiparticle peak and a Hubbard band. It works in a large range of parameters, and therefore can be used for the exploration of real materials using LDA+DMFT.Comment: 30 pages, 7 figure

Comparing gully length and average gully width relationships on two geological sediments of varying vulnerability to erosion in the north central Nigeria

Gully erosion is an environmental problem that confronts the international community. This study was undertaken to investigate the relationships between gully length and average gully width on two geological sediments of varying resistance to erosion. Thirty-seven and five gully samples formed respectively on two homogenous geological sediments (the Ajalli Sandstones (AS) and the Upper Coal Measures (UCM)) underlying the Idah-Ankpa Plateau of the North Central Nigeria were measured and their lengths (L) and average widths (W) were subjected to correlation analyses and the sample bivariate regression to examine and compare their relationships on the two formations. Results show that on the highly erodible AS, L is positively, poorly, and not significantly correlated with W (R = 0.201, R2 = 0.040), whereas the correlation is stronger, significant, but negative at the 0.05 level on the UCM (R = -0.930, R2 = 0.865). The regression equations show that L is a poor predictor of W on the AS (W1 = 6.387 + 0.03 L1, R2 = 0.040), and a very good predictor of the parameter (W) on the UCM (W2=18.135 – 0.033 L2, R2 = 0.865), which appears as a negative value. And the valid range of gully lengths for the prediction of the average width on the AS can be ranked as 0 = L < ∞ (infinity), whereas the ranking is of the form 0 ≤ L ≤ 549.55 m on the UCM. The study suggests that the correlation of W with L becomes stronger, negative and significant as the resistance to erosion of the geological sediments increases. It also suggests that the predictability of W using L as a tool improves and transforms to a negative value as the resistance to erosion of the formation increases.Keywords: Bivariate regression; correlation; geological sediments; gully erosion; soil erosion; vulnerabilit

Teleportation in a noisy environment: a quantum trajectories approach

We study the fidelity of quantum teleportation for the situation in which quantum logic gates are used to provide the long distance entanglement required in the protocol, and where the effect of a noisy environment is modeled by means of a generalized amplitude damping channel. Our results demonstrate the effectiveness of the quantum trajectories approach, which allows the simulation of open systems with a large number of qubits (up to 24). This shows that the method is suitable for modeling quantum information protocols in realistic environments.Comment: 9 pages, 2 figure

Comparative Assessment between Provisional Sums in Private and Public Client Initiated Project in Nigeria

A project is an activity moderated and measured within its set cost, time and quality. Funding of projects is as important as the project itself. Most projects are either funded by taxpayer’s money (Public initiated projects) or from individual’s pockets (Private initiated projects). Abuja, the capital of Nigeria is still developing after more than 30 years of creation, as evident with the volume of construction projects on going within the city. Cost overrun in the Nigerian construction industry is fast becoming a very popular occurrence especially in Abuja. This paper aims to conduct a comparative assessment of provisional sums in public and private client initiated projects in Abuja in a view to proffer solutions to the plague of cost and time overrun in construction projects. 50 structured questionnaires were administered to property developers and only 36 were eventually retrieved and employed for data analysis. The data was analysed using Analysis of Variance (ANOVA) and frequency distribution table. Findings revealed that the one-way analysis of variance (ANOVA) between the two groups indicates that p<0.03 meaning that significant difference exist between the percentage differences of provisional sum in a private initiated project and public initiated project. It was also discovered that the Federal, State, and Local tiers of government are the biggest funders of public initiated projects while individuals; banks and churches are the biggest funders of private initiated projects. . The paper concluded that bureaucratic bottlenecks, corruption amongst other factors is responsible for fewer developers in public initiated projects. Government must reduce corruption, operational lapses and promote project continuity to reduce the number of abandoned projects and ensure qualitative delivery. Recommendations include that projects should be awarded and executed as soon as they are tendered to reduce the effect of inflation between tender time and project execution. Keywords: Provisional Sum, Private Initiated Project, Public Initiated Project, Cost, Funding

Preferred Measurements: Optimality and Stability in Quantum Parameter Estimation

We explore precision in a measurement process incorporating pure probe states, unitary dynamics and complete measurements via a simple formalism. The concept of `information complement' is introduced. It undermines measurement precision and its minimization reveals the system properties at an optimal point. Maximally precise measurements can exhibit independence from the true value of the estimated parameter, but demanding this severely restricts the type of viable probe and dynamics, including the requirement that the Hamiltonian be block-diagonal in a basis of preferred measurements. The curvature of the information complement near a globally optimal point provides a new quantification of measurement stability.Comment: 4 pages, 2 figures, in submission. Substantial Extension and replacement of arXiv:0902.3260v1 in response to Referees' remark

Information security awareness amongst students joining higher academic institutions in developing countries: Evidence from Kenya

Although there is a steady use of information technology in institutions of higher learning, little is known about the level of information security awareness (ISA) amongst students joining universities in developing countries and more specifically Africa. The purpose of this study was to investigate ISA amongst undergraduate students at a higher education institution in Kenya. The study made use of a quantitative survey approach. Overall, the study findings indicate that majority of the students surveyed did not possess adequate understanding of ISA. Consequently, we submit that there is a strong need to cultivate ISA culture amongst students joining universities in developing countries. We further recommend that ISA needs to be incorporated in the undergraduate curriculum to help enhance such awareness. Equally, it would be useful for universities to have ISA program as part of the wider university information security management strategy

Evaluation of Selected Cowpea Lines and Cultivars for Inherent Resistance against Cowpea Seed Beetle, Callosobruchus maculatus Fabricius (Coleoptera: Chrysomelidae: Bruchinae)

Four cowpea lines (IT99K-494-6, IT97K-390-2, IT84S-2246-4 and IT06K-141) obtained from the Genetic Resources Centre, International Institute of Tropical Agriculture (IITA), Ibadan Nigeria, one cultivar (Ife Brown) obtained from Institute of Agricultural Research and Training (IAR&T), Obafemi Awolowo University, Ibadan and two cultivars (Drum and Oloyin) obtained from Wazobia Market, Ogbomoso, Nigeria were screened for comparative susceptibility to the infestation of cowpea seed bruchid, Callosobruchus maculatus. The number of eggs laid on IT99K-494-6 (20.05) was significantly (p < 0.05) lower than the number laid on all the local cultivars (56.33-78.83). First filial progeny emergence (0.71) observed in IT99K-494-6 was significantly (p < 0.05) lower than 2.06 and 1.65 observed in Ife Brown and Drum cowpea cultivars, respectively. Percentage seed damage for 1T99k-49-6 (10.14) was significantly lower than the value obtained in 1T06K-141 (49.93) and Drum (47.74). Alkaloids content was significantly higher in IT06K–141 (31.67 mg/100 g) than in other lines and cultivars. Oloyin had the highest flavonoid (51.7 mg/100 g), tannins (43.3 mg/100 g) whereas 1T84S-2246-4 had the highest saponins (61.7 mg/100 g) Drum had the highest terpenoid (33.33 mg/100 g). Steroid was highest in Oloyin and 1T84S-2246-4 (11.67 mg/100 g). Reducing sugar was highest in Oloyin (5.33 mg/100 g) followed by 1T84S-2246–4 (4.3 mg/100 g) and IT06K–141 (4.0 mg/100 g). Significant and positive relationship exists between saponins content and the number of grains without exit holes (r = 0.46, p = 0.04), suggesting that high saponins was contributory to cowpea host plant resistance to the cowpea seed bruchid, C. maculatus. Keywords: cowpea cultivars, Drum, Oloyin, host plant resistanc

COMPARATIVE ASSESSMENT OF CARBON STORAGE IN BIOMASS AND SOIL ORGANIC CARBON IN TEAK PLANTATION OF DIFFERENT AGES IN YEWA NORTH, OGUN STATE, NIGERIA

Tree act as a sink for CO2 by fixing carbon during photosynthesis and is a vital tool to alleviate climate change through CO2 absorption from the atmosphere. This study was conducted to assess carbon storage in tree biomass and soil carbon stock in Teak (Tectona grandis) plantations of different age series (5, 9 and 12 years). Data were collected on diameter at breast height (Dbh) and total height (TH) of all the trees in a sample plot of 1000 m2 in each plantation of age series. Carbon stored was evaluated based on tree growth variables, soil parameters and above ground biomass. Topsoil and subsoil (0-15 and 15-30 cm) samples collected from three sites were analyzed for organic carbon (OC) following standard methods.  Mean diameter at breast height were 67.11, 45.42, and 21.35 cm ha-1 and the mean volumes were 0.39, 0.16 and 0.02 m3ha-1 for 12, 9 and 5 years old were significant different (p<0.05). The highest value of total soil organic carbon (TSOC) was 8464.65 t.ha-1 for the 12year-old followed by 4430.25 t.ha-1 for 9 years old stand and 3004.95 t.ha-1 for 5years old were significant different (p<0.05) respectively. The total soil organic carbon per hectare were higher for the older than the younger Tectona grandis stand (8464.65 t.ha-1, 4430.25 t.ha-1 and 3004.95 t.ha-1) were significant different (p<0.05). Total carbon storage by soil and in biomass (CSB) was 15899.85 and 49.31 tons.ha-1 and total carbon accumulated by the plantation under investigation was in the order of 12 years old > 9 years old > 5 years old, respectively. The results of this study confirm that teak has good potentials to offer carbon sequestration through its soil and accumulate large amount of biomass carbon. The plantation ownership should be guided properly on the management activities such as thinning, pruning and weeding operation as well as indiscriminate removal of individual caused by anthropogenic activities should be avoided.     &nbsp

Cannibalism as a life boat mechanism

Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one