4,768 research outputs found
Spatial changes of land use pattern in Guzelbahce district (Izmir)
The primary issues related the spatial organization of urban settlements are based on the development of density and land use decisions leading due to the market mechanisms. The current spatial land use pattern of cities have emerged depending various factors such as the migration movements increased rapidly from the 1950s, the rapid and uncontrolled urbanization, the pressures of rent directing the market mechanisms, etc. This urbanization process also has accompanied many problems as the insecure construction for disasters, dense and solid urban texture, various weaknesses or deficiencies of urban infrastructure. As a consequence of the evaluation for social facility areas (gaps in urban area, open and green areas, etc.) as "potential investment areas", the loss of solid - void ratio and dense built-environment have been experienced in urban centres and also urban development directions. The main aim of this study is to examine the spatial effects of land use decisions between the years of 2002-2017 under the influence of the Law 6360 in terms of urban planning discipline. These spatial variations related land use pattern are determined using Google Earth and Geographical Information Systems (GIS). According to the results, it is clearly understood that current land use patterns in Guzelbahce district have changed significantly in 15-years period. The results of analyses related the case area which the urban sprawl has seen are discussed and a variety of policies have been developed. © Authors 2018. CC BY 4.0 License
Physics of randomness and regularities for cities, languages, and their lifetimes and family trees
Time evolution of the cities and of the languages is considered in terms of
multiplicative noise and fragmentation processes; where power law (Pareto-Zipf
law) and slightly asymmetric log-normal (Gauss) distribution result for the
size distribution of the cities and for that of the languages, respectively.
The cities and the languages are treated differently (and as connected; for
example, the languages split in terms of splitting the cities, etc.) and thus
two distributions are obtained in the same computation at the same time.
Evolutions of lifetimes and families for the cities and the languages are also
studied. We suggest that the regularities may be evolving out of randomness, in
terms of the relevant processes.Comment: 22 pages including all figures; for Int. J. Mod. Phys. C 18 (2007
Exciting Andreev pairs in a superconducting atomic contact
The Josephson effect describes the flow of supercurrent in a weak link, such
as a tunnel junction, nanowire, or molecule, between two superconductors. It is
the basis for a variety of circuits and devices, with applications ranging from
medicine to quantum information. Currently, experiments using Josephson
circuits that behave like artificial atoms are revolutionizing the way we probe
and exploit the laws of quantum physics. Microscopically, the supercurrent is
carried by Andreev pair states, which are localized at the weak link. These
states come in doublets and have energies inside the superconducting gap.
Existing Josephson circuits are based on properties of just the ground state of
each doublet and so far the excited states have not been directly detected.
Here we establish their existence through spectroscopic measurements of
superconducting atomic contacts. The spectra, which depend on the atomic
configuration and on the phase difference between the superconductors, are in
complete agreement with theory. Andreev doublets could be exploited to encode
information in novel types of superconducting qubits.Comment: Submitted to Natur
Confinement and the analytic structure of the one body propagator in Scalar QED
We investigate the behavior of the one body propagator in SQED. The self
energy is calculated using three different methods: i) the simple bubble
summation, ii) the Dyson-Schwinger equation, and iii) the Feynman-Schwinger
represantation. The Feynman-Schwinger representation allows an {\em exact}
analytical result. It is shown that, while the exact result produces a real
mass pole for all couplings, the bubble sum and the Dyson-Schwinger approach in
rainbow approximation leads to complex mass poles beyond a certain critical
coupling. The model exhibits confinement, yet the exact solution still has one
body propagators with {\it real} mass poles.Comment: 5 pages 2 figures, accepted for publication in Phys. Rev.
Tunable Superconducting Phase Transition in Metal-Decorated Graphene Sheets
Using typical experimental techniques it is difficult to separate the effects
of carrier density and disorder on the superconducting transition in two
dimensions. Using a simple fabrication procedure based on metal layer
dewetting, we have produced graphene sheets decorated with a non-percolating
network of nanoscale tin clusters. These metal clusters both efficiently dope
the graphene substrate and induce long-range superconducting correlations. This
allows us to study the superconducting transition at fixed disorder and
variable carrier concentration. We find that despite structural inhomogeneity
on mesoscopic length scales (10-100 nm), this material behaves electronically
as a homogenous dirty superconductor. Our simple self-assembly method
establishes graphene as an ideal tunable substrate for studying induced
two-dimensional electronic systems at fixed disorder and our technique can
readily be extended to other order parameters such as magnetism
Superconducting atomic contacts inductively coupled to a microwave resonator
We describe and characterize a microwave setup to probe the Andreev levels of
a superconducting atomic contact. The contact is part of a superconducting loop
inductively coupled to a superconducting coplanar resonator. By monitoring the
resonator reflection coefficient close to its resonance frequency as a function
of both flux through the loop and frequency of a second tone we perform
spectroscopy of the transition between two Andreev levels of highly
transmitting channels of the contact. The results indicate how to perform
coherent manipulation of these states.Comment: 14 pages, 10 figures, to appear in special issue on break-junctions
in JOPC
Heat Transfer Operators Associated with Quantum Operations
Any quantum operation applied on a physical system is performed as a unitary
transformation on a larger extended system. If the extension used is a heat
bath in thermal equilibrium, the concomitant change in the state of the bath
necessarily implies a heat exchange with it. The dependence of the average heat
transferred to the bath on the initial state of the system can then be found
from the expectation value of a hermitian operator, which is named as the heat
transfer operator (HTO). The purpose of this article is the investigation of
the relation between the HTOs and the associated quantum operations. Since, any
given quantum operation on a system can be realized by different baths and
unitaries, many different HTOs are possible for each quantum operation. On the
other hand, there are also strong restrictions on the HTOs which arise from the
unitarity of the transformations. The most important of these is the Landauer
erasure principle. This article is concerned with the question of finding a
complete set of restrictions on the HTOs that are associated with a given
quantum operation. An answer to this question has been found only for a subset
of quantum operations. For erasure operations, these characterizations are
equivalent to the generalized Landauer erasure principle. For the case of
generic quantum operations however, it appears that the HTOs obey further
restrictions which cannot be obtained from the entropic restrictions of the
generalized Landauer erasure principle.Comment: A significant revision is made; 33 pages with 2 figure
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