859 research outputs found
Local current distribution at large quantum dots (QDs): a self-consistent screening model
We report the implementation of the self-consistent Thomas-Fermi screening
theory, together with the local Ohm's law to a quantum dot system in order to
obtain local current distribution within the dot and at the leads. We consider
a large dot (size
nm) defined by split gates, and coupled to the leads. Numerical
calculations show that the non-dissipative current is confined to the
incompressible strips. Due to the non-linear screening properties of the 2DES
at low temperatures, this distribution is highly sensitive to external magnetic
field. Our findings support the phenomenological models provided by the
experimental studies so far, where the formation of the (direct) edge channels
dominate the transport.Comment: 6 Pages, 2 Figure
Tensor Renormalization Group: Local Magnetizations, Correlation Functions, and Phase Diagrams of Systems with Quenched Randomness
The tensor renormalization-group method, developed by Levin and Nave, brings
systematic improvability to the position-space renormalization-group method and
yields essentially exact results for phase diagrams and entire thermodynamic
functions. The method, previously used on systems with no quenched randomness,
is extended in this study to systems with quenched randomness. Local
magnetizations and correlation functions as a function of spin separation are
calculated as tensor products subject to renormalization-group transformation.
Phase diagrams are extracted from the long-distance behavior of the correlation
functions. The approach is illustrated with the quenched bond-diluted Ising
model on the triangular lattice. An accurate phase diagram is obtained in
temperature and bond-dilution probability, for the entire temperature range
down to the percolation threshold at zero temperature.Comment: Added comment. Published version. 8 pages, 7 figures, 1 tabl
The spin-split incompressible edge states within empirical Hartree approximation at intermediately large Hall samples
A self-consistent Thomas-Fermi-Poisson based calculation scheme is used to
achieve spin resolved incompressible strips (ISs). The effect of exchange and
correlation is incorporated by an empirically induced g factor. A local version
of the Ohm's law describes the imposed fixed current, where the discrepancies
of this model are resolved by a relevant spatial averaging process. The
longitudinal resistance is obtained as a function of the perpendicular (strong)
magnetic field at filling factor one and two plateaus. Interrelation between
the ISs and the longitudinal zeros is explicitly shown.Comment: EP2DS-17 Proceedings, 6 Pages, 2 Figure
Non-Abelian pp-waves in D=4 supergravity theories
The non-Abelian plane waves, first found in flat spacetime by Coleman and
subsequently generalized to give pp-waves in Einstein-Yang-Mills theory, are
shown to be 1/2 supersymmetric solutions of a wide variety of N=1 supergravity
theories coupled to scalar and vector multiplets, including the theory of SU(2)
Yang-Mills coupled to an axion \sigma and dilaton \phi recently obtained as the
reduction to four-dimensions of the six-dimensional Salam-Sezgin model. In this
latter case they provide the most general supersymmetric solution. Passing to
the Riemannian formulation of this theory we show that the most general
supersymmetric solution may be constructed starting from a self-dual Yang-Mills
connection on a self-dual metric and solving a Poisson equation for e^\phi. We
also present the generalization of these solutions to non-Abelian AdS pp-waves
which allow a negative cosmological constant and preserve 1/4 of supersymmetry.Comment: Latex, 1+12 page
A note on the M5 brane anomaly
The problem of the M5 brane anomaly cancellation is addressed. We reformulate
FHMM construction making explicit the relation with the M5 brane SUGRA
solution. We suggest another solution to the magnetic coupling equation which
doesn't need anomalous SO(5) variation of the 3-form potential and coincides
with the SUGRA solution outside smoothed out core of the magnetic source.
Chern-Simons term evaluated on this solution generates the same anomaly inflow
as achieved by FHMM.Comment: 5 pages, LaTe
The Relationship between Human Resource Management Practices and Organizational Commitment: A Field Study
AbstractTo begin with, of the most important factors that affect the operational performance of the companies is the human resources. Therefore, the development of organizational commitment needs effective human resource management practices. In organizational behavior and industrial and organizational psychology, organizational commitment is the individual's psychological attachment to the organization. Organizational commitment predicts work variables such as turnover, organizational citizenship behavior, and job performance. The current study is intended to provide analysis of the relationships between HRM practices and organizational commitment in companies which operate in the province of Konya/Turkey. From various previous studies, 56 HRM practices items were adopted for this study. These include “manufacturing and human resources fit, behavior and attitude, team activities, interaction facilitation, incentives to meet objectives, training on job skills, training in multiple functions, communication of strategy, feedback on performance”. In this study, Pfeffer (1998)’s scale of human resources management practices and Mowday & Steers (1979)’s organizational commitment scale, Ahmad, & Schroeder (2003) version were used. Data was analyzed using descriptive statistics to project the respondents’ profiles as well as the general patterns of the variations in the HRM variables and organizational commitment. Correlations and multiple regression, statistic regression analysis were used to explore the relationship between the variables involved in the study. As a result of analysis of the findings from top, middle and, the first-tier managers (n=169) except for “training on job skills”. It was found that there was a strong and statistically positive significant relationship between other HRM variables and organizational commitment. The findings of the study provide support for the variables concerned and are confirmed by the results of the previous studies
Spatial Distribution of the Incompressible Strips at Aharonov-Bohm Interferometer
In this work, the edge physics of an Aharonov-Bohm interferometer (ABI)
defined on a two dimensional electron gas, subject to strong perpendicular
magnetic field B, is investigated. We solve the three dimensional Poisson
equation using numerical techniques starting from the crystal growth parameters
and surface image of the sample. The potential profiles of etched and gate
defined geometries are compared and it is found that the etching yields a
steeper landscape. The spatial distribution of the incompressible strips is
investigated as a function of the gate voltage and applied magnetic field,
where the imposed current is confined to. AB interference is investigated due
to scattering processes between two incompressible "edge-states".Comment: 5 pages, 3 figure
Determination of acrylamide in three different bread types by an in-house validated LC-MS/MS method
A rapid and reliable liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) method was developed for the determination of acrylamide in three different local bread types; wheat bread, bran bread, whole wheat bread. Acrylamide analyses were made in crust parts of the 85 bread samples. The method was linear up to 750 μg kg–1 food with a determination coeffi cient of 0.999. Recovery rate was found 99.3% with limit of detection and limit of quantifi cation values of 1.5 μg kg–1 and 5.0 μg kg–1, respectively. Certifi ed reference materials of crisp bread were analysed and acrylamide contents of these samples were found in the range cited in the certifi cates. Statistical correlations were investigated between acrylamide contents and protein contents, reducing sugar contents, moisture contents, pH, and colour parameters (L*, a*, b*) of bread samples. Sample preparation procedure and chromatographic conditions of acrylamide analysis were investigated in more detail, and a rapid, accurate, precise, and reliable analysis method was developed
Using an analytical process to contextualise architectural prototypes for metro stations
In order to meet the pressures of a growing population and employment base, a developing city in the Middle East is planning a new public transport system to allow its sustainable growth. Introducing a new mode of public transport to a city that has a complex urban structure and a dependency on car use necessitates specific design responses to inform the station design process. This paper focuses on a study at the micro scale level that addresses the impact of evidence-based design on contextualised architectural station prototypes. Furthermore, it addresses the processes of working with an architectural design office in creating dynamic design iterations. The research here is presented from a perspective of the process of iterative analytical study to real time projects, reflecting on the balance between academia and practice. In order to construct a set of design principles to station locations, three layers of potential movement patterns are analysed using agents based modelling: movement from station exits; movement towards station entrances and background movement generated through the spatial accessibility values of the surrounding context. In that respect, each prototype station has been contextualised to its unique site. Design proposals developed by architectural teams are informed through fine grain analysis of urban features such as pavement widths and signage locations. The analyses also inform the landscape design process through the positioning of street furniture in relation to potential movement patterns as well as the effect of shading and public realm quality through option testing. To integrate stations within their contexts they must have simple entrances and clear orientation from the points of exit. Overall, the dynamic nature of agent based modelling allows for rapid design feedback to occur permitting an iterative process of design development and optimisation
Exact string background from a WZW model based on the Heisenberg group
A WZW model for the non-semi-simple D-dimensional Heisenberg group, which
directly generalizes the E_{2}^{c} group, is constructed. It is found to
correspond to an D-dimensional string background of plane-wave type with
physical Lorentz signature D-2. Perturbative and non-perturbative
considerations lead both to an integer central charge c=D.Comment: 9 pages, LATEX, THEF-NYM 94.
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