Hydrogeology and Groundwater Quality of Deep and Shallow Boreholes in Kano Metropolis, Northwestern Nigeria

The study area is located in the Kano Municipal. It is bounded by latitudes 11°51´ to 12°06´N and longitudes 8°23´ to 8°38´ E covering an area of about 770.063 Km2. It lies on the average altitude of 478m above sea level, and is generally undulating lowland. The relief is greatly influenced by the geology; characterized by small, blocky and low laying outcrops. Twenty (20) samples of groundwater collected from the study area from both deep (about 200m) and shallow boreholes, following the standard procedure as prescribed by APHA Guidelines. The analysis was achieved using Atomic Absorption Spectrometer (AAS-Varian AA240Fs), Direct reading Photometer (Hanna model), Titrimetric method, and Flame photometer (FPF9 Jenwy model).The interpretation of groundwater chemistry of the samples suggest that most of the samples analysed are within the WHO and Nigerian Standards for drinking, while some have concentrations beyond desirable limits. However, the concentrations of some elements such as Pb, above permissible limits in the samples analyzed have created a concern over the suitability of the water for drinking and other domestic uses. The assessment of water for irrigation indicates that most of the samples are suitable for irrigational purposes. The result of the laboratory analysis revealed that the selected ions were present in varying concentrations in the study area. The chemical parameters of water samples from the boreholes were plotted using AquaChem and revealed interaction between the groundwater and aquifer materials, and identified important data trends and groupings. Keywords: Water quality, analysis, WHO, SON, AquaChem, permissible limits, anion, cation, Kano

Lineaments Analysis to Identify Favourable Areas for Groundwater in Kano City, Northwestern Nigeria

This work was carried out to investigate groundwater potentials of Kano city using lineament analysis, and to study the relationship between the characteristics and occurrence of groundwater in aquifers of about 200m deep in crystalline basement rocks of the area by examining the possibility of groundwater occurrence at such depths; despite the general understanding that fractures closes with depth. It shows the use of LANDSAT ETM+ imagery and geological map to investigate areas favorable for groundwater development.  This was achieved by plotting the lineament trends, and lineament density to know the groundwater potentials. Rose (azimuth-frequency) diagram of the lineaments delineated on the imagery shows trends in the directions of N-S, E-W, NE-SW, and NW-SE. The dominant trend is NW-SE. The analyses have shown that the study area has numerous fractures whose major trends are mainly in north-south and northwestern-southeastern directions. Lineament density map shows the cross-cutting lineaments are relatively high in areas around the north-eastern and south-western parts of the study area but low in the other areas. The zones of high lineament intersection density are feasible zones for groundwater prospecting.  The positions of deep boreholes on the map of the area do not coincide with the cross cutting lineaments, and are therefore the yields of the deep boreholes are not sustainable. Keywords: Lineaments, groundwater, boreholes, aquifer, fracture

Time-dependent quantum transport in a resonant tunnel junction coupled to a nanomechanical oscillator

We present a theoretical study of time-dependent quantum transport in a resonant tunnel junction coupled to a nanomechanical oscillator within the non-equilibrium Green's function technique. An arbitrary voltage is applied to the tunnel junction and electrons in the leads are considered to be at zero temperature. The transient and the steady state behavior of the system is considered here in order to explore the quantum dynamics of the oscillator as a function of time. The properties of the phonon distribution of the nanomechnical oscillator strongly coupled to the electrons on the dot are investigated using a non-perturbative approach. We consider both the energy transferred from the electrons to the oscillator and the Fano factor as a function of time. We discuss the quantum dynamics of the nanomechanical oscillator in terms of pure and mixed states. We have found a significant difference between a quantum and a classical oscillator. In particular, the energy of a classical oscillator will always be dissipated by the electrons whereas the quantum oscillator remains in an excited state. This will provide useful insight for the design of experiments aimed at studying the quantum behavior of an oscillator.Comment: 24 pages, 10 figure

Origin of the Pseudogap in High-Temperature Cuprate Superconductors

Cuprate high-temperature superconductors exhibit a pseudogap in the normal state that decreases monotonically with increasing hole doping and closes at x \approx 0.19 holes per planar CuO2 while the superconducting doping range is 0.05 < x < 0.27 with optimal Tc at x \approx 0.16. Using ab initio quantum calculations at the level that leads to accurate band gaps, we found that four-Cu-site plaquettes are created in the vicinity of dopants. At x \approx 0.05 the plaquettes percolate, so that the Cu dx2y2/O p{\sigma} orbitals inside the plaquettes now form a band of states along the percolating swath. This leads to metallic conductivity and below Tc to superconductivity. Plaquettes disconnected from the percolating swath are found to have degenerate states at the Fermi level that split and lead to the pseudogap. The pseudogap can be calculated by simply counting the spatial distribution of isolated plaquettes, leading to an excellent fit to experiment. This provides strong evidence in favor of inhomogeneous plaquettes in cuprates.Comment: 24 pages (4 pages main text plus 20 pages supplement

Reinforcing teacher’s role in retaining students’ interests discussing online in their learning process at Malaysian tertiary institutions

Many studies from the literature related to asynchronous online discussions among tertiary students provide various advantages such as allowing students’ flexibility to provide feedbacks [38], enabling their knowledge construction [30], developing their critical thinking [39], and interacting with the lecturers regardless of time and space [1]. Thus, the use of online discussion has further become predominant to support tertiary education. Likewise in Malaysian context, research related to online discussion has demonstrated increased confidence in students’ learning. Although the findings showed positive response, there are studies [20], [3], [29], [24] proved otherwise mainly because of the teachers’ weaknesses in keeping students’ interests and motivation to use online discussions in their learning process. Based on Ames’ [4] teaching strategies and Keller’s [21] ARCS model, a systematic guidance was developed for teachers to properly help students discussing online in completing their assignments. With reference to this systematic guidance, a qualitative case study on how to retain the students’ motivation using online discussion was conducted. The respondents were final year students working in small groups. Each respondent was made compulsory to answer a checklist based on the items from Khan [22] that was used to gauge their background skills in using online forum before conducting the study. The research instruments used were online discussions and interviews. The transcripts from the online discussions were analysed using a coding scheme developed from the systematic guidance (developed from Ames’ [21] teaching strategies and Keller’s [21] ARCS model while the data from the interviews with the group leaders were used to support the findings derived from the transcript analysis. The findings revealed that the teaching strategies used in this study were able to retain the students’ interest and motivation to continue discussing online in completing their project assignments

A parallelized disjunctive query based searchable encryption scheme for big data

Searchable Encryption (SE) allows a client to search over large amounts of encrypted data outsourced to the Cloud. Although, this helps to maintain the confidentiality of the outsourced data but achieving privacy is a difficult and resource intensive task. With the increase in the query effectiveness, i.e., by shifting from single keyword SE to multi-keyword SE there is a notable drop in the efficiency. This motivates to make use of the advances in the multi-core architectures and multiple threads where the search can be delegated across different threads to perform search in a parallel fashion. The proposed scheme is based on probabilistic trapdoors that are formed by making use of the property of modular inverses. The use of probabilistic trapdoors helps resist distinguishability attacks. The rigorous security analysis helps us to appreciate the advantage of having a probabilistic trapdoor. Furthermore, to validate the performance of the proposed scheme, it is implemented and deployed onto the British Telecommunication's Public Cloud offering and tested over a real speech corpus. The implementation is also extended to anticipate the performance gain by using the multi-core architecture that helps to maintain the lightweight property of the scheme

The effect of transverse magnetic correlations on a coupled order parameter: shifted transition temperatures and thermal hysteresis

We use a Green's function method with Random Phase Approximation to show how magnetic correlations may affect electric polarization in multiferroic materials with magnetic-exchange-type magnetoelectric coupling. We use a model spin 1/2 ferromagnetic ferroelectric system but our results are expected to apply to multiferroic materials with more complex magnetic structures. In particular, we find that transverse magnetic correlations result in a change in the free energy of the ferroelectric solutions leading to the possibility for thermal hysteresis of the electric polarization above the magnetic Curie temperature. Although we are motivated by multiferroic materials, this problem represents a more general calculation of the effect of fluctuations on coupled order parameters

Quantum transport in a resonant tunnel junction coupled to a nanomechanical oscillator

We discuss the quantum transport of electrons through a resonant tunnel junction coupled to a nanomechanical oscillator at zero temperature. By using the Green's function technique we calculate the transport properties of electrons through a single dot strongly coupled to a single oscillator. We consider a finite chemical potential difference between the right and left leads. In addition to the main resonant peak of electrons on the dot, we find satellite peaks due to the creation of phonons. These satellite peaks become sharper and more significant with increasing coupling strength between the electrons and the oscillator. We also consider the energy transferred from the electrons to the oscillator.Comment: Updated in response to referees' comments. Section IV amended including figure

Gap opening in the zeroth Landau level in gapped graphene: Pseudo-Zeeman splitting in an angular magnetic field

We present a theoretical study of gap opening in the zeroth Landau level in gapped graphene as a result of pseudo-Zeeman interaction. The applied magnetic field couples with the valley pseudospin degree of freedom of the charge carriers leading to the pseudo-Zeeman interaction. To investigate its role in transport at the Charge Neutrality Point (CNP), we study the integer quantum Hall effect (QHE) in gapped graphene in an angular magnetic field in the presence of pseudo-Zeeman interaction. Analytical expressions are derived for the Hall conductivity using Kubo-Greenwood formula. We also determine the longitudinal conductivity for elastic impurity scattering in the first Born approximation. We show that pseudo-Zeeman splitting leads to a minimum in the collisional conductivity at high magnetic fields and a zero plateau in the Hall conductivity. Evidence for activated transport at CNP is found from the temperature dependence of the collisional conductivity.Comment: 20 pages, 4 figures, Accepted in J. Phys. Condensed matte

The Antiferromagnetic Band Structure of La2CuO4 Revisited

Using the Becke-3-LYP functional, we have performed band structure calculations on the high temperature superconductor parent compound, La2CuO4. Under the restricted spin formalism (rho(alpha) equal to rho(beta)), the R-B3LYP band structure agrees well with the standard LDA band structure. It is metallic with a single Cu x2-y2/O p(sigma) band crossing the Fermi level. Under the unrestricted spin formalism (rho(alpha) not equal to rho(beta)), the UB3LYP band structure has a spin polarized antiferromagnetic solution with a band gap of 2.0 eV, agreeing well with experiment. This state is 1.0 eV (per formula unit) lower than that calculated from the R-B3LYP. The apparent high energy of the spin restricted state is attributed to an overestimate of on-site Coulomb repulsion which is corrected in the unrestricted spin calculations. The stabilization of the total energy with spin polarization arises primarily from the stabilization of the x2-y2 band, such that the character of the eigenstates at the top of the valence band in the antiferromagnetic state becomes a strong mixture of Cu x2-y2/O p(sigma) and Cu z2/O' p(z). Since the Hohenberg-Kohn theorem requires the spin restricted and spin unrestricted calculations give exactly the same ground state energy and total density for the exact functionals, this large disparity in energy reflects the inadequacy of current functionals for describing the cuprates. This calls into question the use of band structures based on current restricted spin density functionals (including LDA) as a basis for single band theories of superconductivity in these materials.Comment: 13 pages, 8 figures, to appear in Phys. Rev. B, for more information see http://www.firstprinciples.co