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Search Results: 1 - 10 of 332933 matches for " Michael J. Haule "
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Population, Development and Deforestation in Songea District, Tanzania  [PDF]
Michael J. Haule
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.51004
Abstract:

Deforestation is a phenomenon that forms part of environmental degradation. The fact that deforestation is both a source and contributor to global warming, as it reduces the carbon sinks, cannot be contested [1]. A case study research was carried out in Songea Tanzania aimed at establishing whether there was differential participation of people of different demographic characteristics in those activities that lead into tree cover decline. The study revealed that people of different age group and, sex categories played different roles in activities that lead to deforestation such as felling trees for firewood and felling trees for establishing and/or for expanding farms. It was observed that age group and sex categories influenced one’s involvement or participation in deforestation thus contributing differently by both activity and degree of forest cover reduction. This literally means that people of different demographic characteristics of age and sex contributed differently to the ailing deforestation process. From this end, it is logical and implicit arguing that the identification of actors in deforestation-related activities confirms the disaggregated manner by which population acts on the environment. Development of blanket conservation packages that are not focused on age group and sex categories of members the population in question remains too general and in-effective. To be precise, the planning and implementation of effective conservation initiatives has to take into account demographic characteristics of the population in question. The observed reality is that the population engages with the environment not as a unit but in its disaggregated manner, i.e. based on its demographic sub-categories [2]. The theory behind a successful conservation initiative is based on unveiling the mechanism by which population acts when resulting to deforestation.

Changes in Human Population Characteristics and Environmental Change in the West Matogoro Catchment Area of Songea, Tanzania  [PDF]
Michael J. Haule
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.512064
Abstract: The study was carried out in West Matogoro Catchment Area (WMCA) of Songea, Tanzania, to establish whether for the period between intercensal periods 1978-1988 and 1988-2002, and between 2002 and 2005 characteristics of human population of the area had changed in terms of size, age structure and sex composition. In case it did, then the study had to establish whether such changes may be used to explain the observed forest cover change that occurred in the area. Establishing whether the observed changes were proportionate was important in linking the relationship among factors at hand. The study partly tested the thesis by Liu and others which linked human population changes and their implications to the panda habitat [1]. The findings indicated existence of changes in human population characteristics for the period under review. Variations in terms of population size, age structure and sex composition were realized. While growth was measured by the total population and size of age group of the environmentally active population as identified by the study by Haule, sex composition was determined by sex ratios [2]. The environmentally active age group included males aged 20 to 44 and females aged 10 to 44, i.e. the key actors in felling trees for farm expansion and for firewood respectively. Geographic Information System (GIS) evidence indicated progressive forest cover deterioration. When compared, the changes in human population characteristics and those of the forest cover were noted to be un-proportional. Variations were in terms of increase in human population size and expansion of age group of the “actors” thus attributed to the augmenting deforestation. A positive relationship was demonstrated between population growth, expansion of age segment of the key actors and expanded deforestation. We reiterate that any sustainable measures to address the environmental issues should take into account changes in demographic characteristics of the in Situ population which forms the locus of the interface between population and environment. These factors signify the intensity and duration of the involved forces that characterize forest cover quality.
Inelastic tunneling through mesoscopic structures
K. Haule,J. Bonca
Physics , 1998, DOI: 10.1103/PhysRevB.59.13087
Abstract: Our objective is to study resonant tunneling of an electron in the presence of inelastic scattering by optical phonons. Using a recently developed technique, based on exact mapping of a many-body problem onto a one-body problem, we compute transmission through a single site at finite temperatures. We also compute current through a single site at finite temperatures and an arbitrary strength of the potential drop over the tunneling region. Transmission vs. incident electron energy at finite temperatures displays additional peaks due to phonon absorption processes. Current at a voltage bias smaller than the phonon frequency is dominated by elastic processes. We apply the method to an electron tunneling through the Aharonov-Bohm ring coupled to optical phonons. Elastic part of electron-phonon scattering does not affect the phase of the electron. Dephasing occurs only through inelastic processes.
What is the valence of a correlated solid? The double life of delta-plutonium
J. H. Shim,K. Haule,G. Kotliar
Physics , 2006, DOI: 10.1038/nature05647
Abstract: Plutonium displays phase transitions with enormous volume differences among its phases and both its Pauli like magnetic susceptibility and resistivity are an order of magnitude larger than those of simple metals. Curium is also highly resistive but its susceptibility is Curie-like at high temperatures and orders antiferromagnetically at low temperatures. The anomalous properties of the late actinides stem from the competition between the itinerancy and localization of its f electrons, which makes the late actinides elemental strongly correlated materials. A central problem in this field is to understand the mechanism by which these materials resolve these conflicting tendencies. In this letter we identify the electronic mechanisms responsible for the anomalous behaviour of late actinides. We revisit the concept of valence using theoretical approach that treats magnetism, Kondo screening, atomic multiplet effects, spin orbit coupling and crystal field splitting on the same footing. Plutonium is found to be in a rare mixed valent state, namely its ground state is a superposition of two distinct valencies. Curium settles in a single valence magnetically ordered state at low temperatures. The f7 atomic configuration of Curium is contrasted with the multiple configuration manifolds present in Plutonium ground state which we characterize by a valence histogram. The balance between the Kondo screening and magnetism is determined by the competition between spin orbit coupling and the strength of atomic multiplets which is in turn regulated by the degree of itinerancy. The approach presented here, highlights the electronic origin of the bonding anomalies in plutonium and can be applied to predict generalized valences and the presence or absence of magnetism in other compounds starting from first principles.
X-ray absorption branching ratio in actinides: LDA+DMFT approach
J. H. Shim,K. Haule,G. Kotliar
Physics , 2008, DOI: 10.1209/0295-5075/85/17007
Abstract: To investigate the x-ray absorption (XAS) branching ratio from the core 4d to valence 5f states, we set up a theoretical framework by using a combination of density functional theory in the local density approximation and Dynamical Mean Field Theory (LDA+DMFT), and apply it to several actinides. The results of the LDA+DMFT reduces to the band limit for itinerant systems and to the atomic limit for localized f electrons, meaning a spectrum of 5f itinerancy can be investigated. Our results provides a consistent and unified view of the XAS branching ratio for all elemental actinides, and is in good overall agreement with experiments.
Modelling the Localized to Itinerant Electronic Transition in the Heavy Fermion System CeIrIn5
J. H. Shim,K. Haule,G. Kotliar
Physics , 2008, DOI: 10.1126/science.1149064
Abstract: We address the fundamental question of crossover from localized to itinerant state of a paradigmatic heavy fermionmaterial CeIrIn5. The temperature evolution of the one electron spectra and the optical conductivity is predicted from first principles calculation. The buildup of coherence in the form of a dispersive many body feature is followed in detail and its effects on the conduction electrons and optical conductivity of the material is revealed. We find multiple hybridization gaps and link them to the crystal structure of the material. Our theoretical approach explains the multiple peak structures observed in optical experiments and the sensitivity of CeIrIn5 to substitutions of the transition metal element and may provide a microscopic basis for the more phenomenological descriptions currently used to interpret experiments in heavy fermion systems.
Correlated electronic structure of LaOFeAs
K. Haule,J. H. Shim,G. Kotliar
Physics , 2008, DOI: 10.1103/PhysRevLett.100.226402
Abstract: We compute the electronic structure, momentum resolved spectral function and optical conductivity of the new superconductor LaO$_{1-x}$F$_x$FeAs within the combination of the Density functional theory and the Dynamical Mean Field Theory. We find that the compound in the normal state is a strongly correlated metal and the parent compound is a bad metal at the verge of the metal insulator transition. We argue that the superconductivity is not phonon mediated.
A new family of iron pnictides: BaFeAs2 and BaFeSb2
J. H. Shim,K. Haule,G. Kotliar
Physics , 2008, DOI: 10.1103/PhysRevB.79.060501
Abstract: We investigate the structural, electronic, and magnetic properties of the hypothetical compound BaFePn2 (Pn = As and Sb), which is isostructural to the parent compound of the high temperature superconductor LaFeAsO1-xFx. Using density functional theory, we show that the Fermi surface, electronic structure and the spin density wave instability of BaFePn2 are very similar to the Fe based superconductors. Additionally, there are very dispersive metallic bands of a spacer Pn layer, which are almost decoupled from FePn layer. Our results show that experimental study of BaFePn2 can test the role of charge and polarization fluctuation, importance of two dimensionality in mechanism of superconductivity.
Finite temperature properties of the 2D Kondo lattice model
K. Haule,J. Bonca,P. Prelovsek
Physics , 1999, DOI: 10.1103/PhysRevB.61.2482
Abstract: Using recently developed Lanczos technique we study finite-temperature properties of the 2D Kondo lattice model at various fillings of the conduction band. At half filling the quasiparticle gap governs physical properties of the chemical potential and the charge susceptibility at small temperatures. In the intermediate coupling regime quasiparticle gap scales approximately linearly with Kondo coupling. Temperature dependence of the spin susceptibility reveals the existence of two different temperature scales. A spin gap in the intermediate regime leads to exponential drop of the spin susceptibility at low temperatures. Unusual scaling of spin susceptibility is found for temperatures above 0.6 J. Charge susceptibility at finite doping reveals existence of heavy quasiparticles. A new low energy scale is found at finite doping.
Investigation into the Effect of Extended Laundering on the KES-F Mechanical Properties of an Easy Care Treated Cotton Fabric  [PDF]
Liberato Venant Haule
Journal of Textile Science and Technology (JTST) , 2016, DOI: 10.4236/jtst.2016.22004
Abstract: The effect of extended laundering on cotton fabric treated with Dimethylol dihydroxyethyleneurea (DMDHEU) easy care finish was investigated and the fabric characterised by crease recovery performance and the Kawabata Evaluation System for Fabrics (KES-F). The KES-F results indicated that the mechanical handle properties of the DMDHEU treated cotton fabrics were affected by both the levels of application of the DMDHEU easy care finishes and the stress relaxation of the fabrics in aqueous conditions.
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