Theoretical Models Research Papers - Academia.edu (original) (raw)

We study theI-Vcharacteristic of mesoscopic systems or quantum dot (QD) attached to a pair of superconducting leads. Interaction effects in the QD are considered through the charging energy of the QD; that is, the treatment of current... more

We study theI-Vcharacteristic of mesoscopic systems or quantum dot (QD) attached to a pair of superconducting leads. Interaction effects in the QD are considered through the charging energy of the QD; that is, the treatment of current transport under a voltage bias is performed within a coupled Poisson nonequilibrium Green function (PNEGF) formalism. We derive the expression for the current in full generality but consider only the regime where transport occurs only via a single particle current. We show for this case and for various charging energies valuesU0and associated capacitances of the QD the effect on theI-Vcharacteristic. Also the influence of the coupling constants on theI-Vcharacteristic is investigated. Our approach puts forward a novel interpretation of experiments in the strong Coulomb regime.

The author considers that whilst nurse tutors teach theory, nurse practitioners go on nursing in the same way that they always have done. There appears to be a chasm dividing theory and practice. This paper describes an attempt to leap... more

The author considers that whilst nurse tutors teach theory, nurse practitioners go on nursing in the same way that they always have done. There appears to be a chasm dividing theory and practice. This paper describes an attempt to leap that chasm. The paper identifies the problem, inherent in the nursing process that creates such difficulties in its implementation. The nursing process alone does not provide an adequate framework for nursing practice. The paper then describes how the translation of theory into practice took place on a ward in Brighton General Hospital, Brighton, England. The barrier between theory and practice is highlighted, along with a description of how the problems this presents to ward staff were overcome. The author considers that the attribution of cause is a key concept in the problem-solving approach, since it generates the question — Why?— and therefore that attribution of cause must be a concept in any model of nursing that is being used to implement the nursing process. The paper provides an example of how nursing models may be adapted, at ward level, to guide everyday practice, whilst retaining the conceptual framework ofthe model. The inference of the paper is that such a process could be applied to other models resulting in a greater use of theory in everyday nursing practice.

Odour detection thresholds, that we have previously obtained, have been analysed by a general equation for selective transport. It is shown that such selective transport can account for some 77% of the total effect. The remainder is due... more

Odour detection thresholds, that we have previously obtained, have been analysed by a general equation for selective transport. It is shown that such selective transport can account for some 77% of the total effect. The remainder is due to a specific size effect, that might involve odour-binding proteins, and a specific effect for aldehydes and carboxylic acids. Our analysis raises

The aim of the present study was to examine an adapted integrated psycho-social model to predict sport injury rehabilitation adherence. A longitudinal prospective design was used whereby 70 patients attending private physiotherapy clinics... more

The aim of the present study was to examine an adapted integrated psycho-social model to predict sport injury rehabilitation adherence. A longitudinal prospective design was used whereby 70 patients attending private physiotherapy clinics completed a battery of questionnaires both pre- and post-rehabilitation treatment based on the adapted framework. All participants were receiving treatment for tendonitis-related injuries. Adherence was monitored prospectively over the entire rehabilitation program using an observational measure of clinic adherence, a self-report measure of home-based adherence, in addition to monitoring attendance at rehabilitation sessions. In the initial phase of rehabilitation learning goal orientation, attitudes and perceived severity were found to predict rehabilitation intention. Intentions were also found to mediate the relationship between the aforementioned variables and clinic rehabilitation. Self-efficacy and self-motivation were predictors of clinic rehabilitation and attendance but not home rehabilitation. During the maintenance phase of rehabilitation coping ability and social support were predictors regarding all three measures of adherence. Implications for practitioners rehabilitating injured athletes are discussed.

Minkowski famously introduced the concept of a space-time continuum in 1908, merging the three dimensions of space with an imaginary time dimension $ i c t ,withtheunitimaginaryproducingthecorrectspacetimedistance, with the unit imaginary producing the correct spacetime distance ,withtheunitimaginaryproducingthecorrectspacetimedistance x^2 - c^2... more

Minkowski famously introduced the concept of a space-time continuum in 1908, merging the three dimensions of space with an imaginary time dimension $ i c t ,withtheunitimaginaryproducingthecorrectspacetimedistance, with the unit imaginary producing the correct spacetime distance ,withtheunitimaginaryproducingthecorrectspacetimedistance x^2 - c^2 t^2 ,andtheresultsofEinstein′sthenrecentlydevelopedtheoryofspecialrelativity,thusprovidinganexplanationforEinstein′stheoryintermsofthestructureofspaceandtime.AsanalternativetoaplanarMinkowskispace−timeoftwospacedimensionsandonetimedimension,wereplacetheunitimaginary, and the results of Einstein's then recently developed theory of special relativity, thus providing an explanation for Einstein's theory in terms of the structure of space and time. As an alternative to a planar Minkowski space-time of two space dimensions and one time dimension, we replace the unit imaginary ,andtheresultsofEinstein′sthenrecentlydevelopedtheoryofspecialrelativity,thusprovidinganexplanationforEinstein′stheoryintermsofthestructureofspaceandtime.AsanalternativetoaplanarMinkowskispace−timeoftwospacedimensionsandonetimedimension,wereplacetheunitimaginary i = \sqrt{-1} ,withtheCliffordbivector, with the Clifford bivector ,withtheCliffordbivector \iota = e_1 e_2 $ for the plane that also squares to minus one, but which can be included without the addition of an extra dimension, as it is an integral part of the real Cartesian plane with the orthonormal basis $ e_1 $ and $ e_2 $. We find that with this model of planar spacetime, using a two-dimensional Clifford multivector, the spacetime metric and the Lorentz transformations follow immediately as properties of the algebra. This also leads to momentum and energy being represented as components of a multivector and we give a new efficient derivation of Compton's scattering formula, and a simple formulation of Dirac's and Maxwell's equations. Based on the mathematical structure of the multivector, we produce a semi-classical model of massive particles, which can then be viewed as the origin of the Minkowski spacetime structure and thus a deeper explanation for relativistic effects. We also find a new perspective on the nature of time, which is now given a precise mathematical definition as the bivector of the plane.

We consider a particle performing a stochastic motion on a one-dimensional lattice with jump widths distributed according to a power-law with exponent μ + 1. Assuming that the walker moves in the presence of a distribution a(x) of targets... more

We consider a particle performing a stochastic motion on a one-dimensional lattice with jump widths distributed according to a power-law with exponent μ + 1. Assuming that the walker moves in the presence of a distribution a(x) of targets (traps) depending on the spatial coordinate x, we study the probability that the walker will eventually find any target (will eventually be trapped). We focus on the case of power-law distributions a(x) ∼ x^-α and we find that as long as μ < α there is a finite probability that the walker will never be trapped, no matter how long the process is. This analytical result, valid on infinite chains, is corroborated by numerical simulations which also evidence the emergence of slow searching (trapping) times in finite-size system. The extension of this finding to higher-dimensional structures is also discussed.

The pulp and paper industry generates significant amounts of waste from various processes consisting of organic and inorganic matter. Due to its composition, the management of pulp and paper mill sludge presents an economic burden for... more

The pulp and paper industry generates significant amounts of waste from various processes consisting of organic and inorganic matter. Due to its composition, the management of pulp and paper mill sludge presents an economic burden for wastewater treatment plants. In South Africa, paper mill sludge is mainly incinerated, landfilled or used for land application. These practices cause environmental and health hazards. In this study, a process of stabilization of paper mill sludge through hydrothermal carbonization is proposed. The quality of biochar produced and energy yield will depend on the elemental composition, calorific value and ash content of the sludge. Results revealed samples are composed of flat fibrous cellulosic morphology, with high volatile matter and little fixed carbon percentage. The main decomposition occurred between 220-400 °C. Sludge from primary clarifier contains the highest ash percentage, hence it was found to be unsuitable for energy recovery through hydroth...

In the analysis and prediction of real-world systems, two of the key problems are nonstationarity (often in the form of switching between regimes) and overfitting (particularly serious for noisy processes). This article addresses these... more

In the analysis and prediction of real-world systems, two of the key problems are nonstationarity (often in the form of switching between regimes) and overfitting (particularly serious for noisy processes). This article addresses these problems using gated experts, consisting of a (nonlinear) gating network, and several (also nonlinear) competing experts. Each expert learns to predict the conditional mean, and each expert adapts its width to match the noise level in its regime. The gating network learns to predict the probability of each expert, given the input. This article focuses on the case where the gating network bases its decision on information from the inputs. This can be contrasted to hidden Markov models where the decision is based on the previous state(s) (i.e. on the output of the gating network at the previous time step), as well as to averaging over several predictors. In contrast, gated experts soft-partition the input space, only learning to model their region. This...

The photochemical behavior of oxyfluorfen [2-chloro-1-(3-etoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene] on two Greek soils was investigated. Soils were sampled from Nea Malgara and Preveza regions, characterized by a different organic... more

The photochemical behavior of oxyfluorfen [2-chloro-1-(3-etoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene] on two Greek soils was investigated. Soils were sampled from Nea Malgara and Preveza regions, characterized by a different organic matter content. Soils were spiked with the diphenyl-ether herbicide and irradiation experiments were performed either in the laboratory with a solar simulator (xenon lamp) or outside, under natural sunlight irradiation; other soil samples were kept in the dark to control the retention reaction. Kinetic parameters of both retention and photochemical reactions were calculated using zero-, first- and second- (Langmuir-Hinshelwood) order equations, and best fit was checked through statistical analysis. The soil behaviors were qualitatively similar but quantitatively different, with the soil sampled from the Nea Malgara region much more sorbent as compared with Preveza soil. All studied reactions followed second-order kinetics and photochemical reaction...

The evaluation of clothing surface area becomes important in analyses of heat exchange between the clothed body and its environment. The evidence accumulated in the studies of radiation area has led to the conclusion that the ratio of... more

The evaluation of clothing surface area becomes important in analyses of heat exchange between the clothed body and its environment. The evidence accumulated in the studies of radiation area has led to the conclusion that the ratio of clothing surface area to body surface area (fcl) may be defined as a function of clothing insulation. However, the effects of clothing fit have been disregarded. Radiation area factors (Ar/AD) were derived from pictures of five subjects wearing four different helicopter pilot suits. While sitting on a seat suspended in the center of a box-shaped frame, photographs were taken of the subjects with a fish-eye lens at 90 equidistant points on the six sides of the frame. The derived Ar/AD of 0.7 +/- 0.18 for the unclothed subjects closely agreed with that reported by Fanger, while it scattered in a relatively wide range for a given suit. The present study proposes a new approach for predicting fcl as related to body volume and the clothing microenvironment ...

In this work, the vibrational spectral analysis was carried out using Raman and infrared spectroscopy in the range 100-4000 cm(-1) and 50-4000 cm(-1), respectively, for the title molecules. The molecular structure, fundamental vibrational... more

In this work, the vibrational spectral analysis was carried out using Raman and infrared spectroscopy in the range 100-4000 cm(-1) and 50-4000 cm(-1), respectively, for the title molecules. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartee Fock (HF) and density functional theory (DFT) method and different basis sets combination. The complete vibrational assignments of wave numbers were made on the basis of potential energy distribution (PED). The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The effects due to the substitutions of methyl group and halogen bond were investigated. The results of the calculations were applied to simulated spectra of the title compounds, which show excellent agreement with observed spectra.

A central component of the primary health care approach in developing countries has been the development and utilization of community-based health workers (CHWs) within the national health system. While the use of these front line workers... more

A central component of the primary health care approach in developing countries has been the development and utilization of community-based health workers (CHWs) within the national health system. While the use of these front line workers has the potential to positively influence health behavior and health status in rural communities, there continues to be challenges to effective implementation of CHW programs. Reports of high turnover rates, absenteeism, poor quality of work, and low morale among CHWs have often been associated with weak organizational and managerial capacity of government health systems. However, no systematic research has examined the contribution of work-related factors to CHW job performance. The research reported in this paper examines the relative influence of reward and feedback factors associated with the community compared to those associated with the health system on the performance of CHWs. The data are drawn from a broader study of health promoters (CHW...

Abstract: The patient submitted to artificial ventilation generally is connected to a high impedance flow source with controlled respiratory cycles to assure volume requirements or to a low impedance pressure source with spontaneous... more

Abstract: The patient submitted to artificial ventilation generally is connected to a high impedance flow source with controlled respiratory cycles to assure volume requirements or to a low impedance pressure source with spontaneous cycles to allow synchronization between his effort and system flow delivery. These two types of cycles represent the initial and final stages of artificial ventilation. The patient who needs a volume guarantee and at the same time presents unstable or insufficient inspiratory effort is difficult to manage with assisted cycles which are analogous to the controlled presence of a high impedance flow source. This paper presents a new approach where the respiratory cycles are obtained by the combination of flow and pressure sources using mathematical modeling. These cycles, named volume assisted pressure supported (VAPS) cycles, are compared with conventional assisted cycles showing a decrease in the patient work of breathing (WOB) during assisted ventilation. The theoretical results have been confirmed by clinical trials.

Purpose. Conduct a social network analysis of the health and non–health related organizations that participate in Bogotá's Ciclovía Recreativa (Ciclovía). Design. Cross-sectional study. Setting. Ciclovía is a multisectoral... more

Purpose. Conduct a social network analysis of the health and non–health related organizations that participate in Bogotá's Ciclovía Recreativa (Ciclovía). Design. Cross-sectional study. Setting. Ciclovía is a multisectoral community-based mass program in which streets are temporarily closed to motorized transport, allowing exclusive access to individuals for leisure activities and physical activity. Subjects. Twenty-five organizations that participate in the Ciclovía. Measures. Seven variables were examined by using network analytic methods: relationship, link attributes (integration, contact, and importance), and node attributes (leadership, years in the program, and the sector of the organization). Analysis. The network analytic methods were based on a visual descriptive analysis and an exponential random graph model. Results. Analysis shows that the most central organizations in the network were outside of the Health sector and include Sports and Recreation, Government, and S...

This manuscript describes the application of a genetic algorithm model for the optimal design of regional wastewater systems comprised of transmission gravitational and pumping sewer pipelines, decentralized treatment plants, and end... more

This manuscript describes the application of a genetic algorithm model for the optimal design of regional wastewater systems comprised of transmission gravitational and pumping sewer pipelines, decentralized treatment plants, and end users of reclaimed wastewater. The algorithm seeks the diameter size of the designed pipelines and their flow distribution simultaneously, the number of treatment plants and their size and location, the pump power, and the required excavation work. The model capabilities are demonstrated through a simplified example application using base runs and sensitivity analyses. Scaling of the proposed methodology to real life wastewater collection and treatment plants design problems needs further testing and developments. The model is coded in MATLAB using the GATOOL toolbox and is available from the authors.

Developing a mass-casualty medical response to the detonation of an improvised nuclear device (IND) or large radiological dispersal device (RDD) requires unique advanced planning due to the potential magnitude of the event, lack of... more

Developing a mass-casualty medical response to the detonation of an improvised nuclear device (IND) or large radiological dispersal device (RDD) requires unique advanced planning due to the potential magnitude of the event, lack of warning, and radiation hazards. In order for medical care and resources to be collocated and matched to the requirements, a [US] Federal interagency medical response-planning group has developed a conceptual approach for responding to such nuclear and radiological incidents. The "RTR" system (comprising Radiation-specific TRiage, TReatment, TRansport sites) is designed to support medical care following a nuclear incident. Its purpose is to characterize, organize, and efficiently deploy appropriate materiel and personnel assets as close as physically possible to various categories of victims while preserving the safety of responders. The RTR system is not a medical triage system for individual patients. After an incident is characterized and safe...

Forest ecosystems are fundamental for the terrestrial biosphere as they deliver multiple essential ecosystem services (ES). In environmental management, understanding ES distribution and interactions and assessing the economic value of... more

Forest ecosystems are fundamental for the terrestrial biosphere as they deliver multiple essential ecosystem services (ES). In environmental management, understanding ES distribution and interactions and assessing the economic value of forest ES represent future challenges. In this study, we developed a spatially explicit method based on a multi-scale approach (MiMoSe-Multiscale Mapping of ecoSystem services) to assess the current and future potential of a given forest area to provide ES. To do this we modified and improved the InVEST model in order to adapt input data and simulations to the context of Mediterranean forest ecosystems. Specifically, we integrated a GIS-based model, scenario model, and economic valuation to investigate two ES (wood production and carbon sequestration) and their trade-offs in a test area located in Molise region (Central Italy). Spatial information and trade-off analyses were used to assess the influence of alternative forest management scenarios on in...

Limb volumes, as would be estimated by the widely used right circular truncated cone model (right circular frustum), were analytically compared to volume estimates that would be obtained if limbs were represented by an elliptical cross... more

Limb volumes, as would be estimated by the widely used right circular truncated cone model (right circular frustum), were analytically compared to volume estimates that would be obtained if limbs were represented by an elliptical cross section. A general expression for the ratio of circular to elliptical limb segmental volumes was developed in terms of the ratio of minimum to maximum limb radial dimensions. Analytical results showed that in general the elliptical representation resulted in smaller calculated limb volumes, with the difference increasing as the ratio of minimum to maximum limb dimension became smaller. However, differences in estimated limb volume between circular and elliptic representations were less than 5% if the minimum to maximum limb dimensions at measured circumference sites were greater than 0.64. It is concluded that although limbs deviate from circularity, the added work of determining minimum and maximum dimensions for each circumference measured, as is ne...

Recently, several theoretical papers have derived relationships for fiber-optic transmission system performance in terms of associated physical layer parameters. At the same time, a large number of detailed experiments have been and... more

Recently, several theoretical papers have derived relationships for fiber-optic transmission system performance in terms of associated physical layer parameters. At the same time, a large number of detailed experiments have been and continue being performed that demonstrate increasing capacities and unregenerated reach. We use this wealth of experimental data to validate the aforementioned relationships, and to propose a set of simple scaling rules for performance. We find that, despite substantial differences in experimental configurations, overall performance in terms of spectral efficiency and unregenerated reach is well explained by scaling rules. These scaling rules will be useful to carriers seeking to understand what they should expect to see in terms of network performance using deployed or easily accessible technology, which may be radically different from hero experiment results. These rules will also be useful to design engineers seeking cost effective tradeoffs to achiev...