27,165 research outputs found
Application of the Kelly Criterion to Ornstein-Uhlenbeck Processes
In this paper, we study the Kelly criterion in the continuous time framework
building on the work of E.O. Thorp and others. The existence of an optimal
strategy is proven in a general setting and the corresponding optimal wealth
process is found. A simple formula is provided for calculating the optimal
portfolio for a set of price processes satisfying some simple conditions.
Properties of the optimal investment strategy for assets governed by multiple
Ornstein-Uhlenbeck processes are studied. The paper ends with a short
discussion of the implications of these ideas for financial markets.Comment: presented at Complex'2009 (Shanghai, Feb. 23-25
Influence of Roughness and Disorder on Tunneling Magnetoresistance
A systematic, quantitative study of the effect of interface roughness and
disorder on the magnetoresistance of FeCovacuumFeCo magnetic tunnel
junctions is presented based upon parameter-free electronic structure
calculations. Surface roughness is found to have a very strong effect on the
spin-polarized transport while that of disorder in the leads (leads consisting
of a substitutional alloy) is weaker but still sufficient to suppress the huge
tunneling magneto-resistance (TMR) predicted for ideal systems
Genome-wide linkage scan for loci associated with epilepsy in Belgian shepherd dogs.
BackgroundIdiopathic epilepsy in the Belgian shepherd dog is known to have a substantial genetic component. The objective of this study was to identify genomic regions associated with the expression of generalized seizures in the Belgian Tervuren and Sheepdog.ResultsDNA from 366 dogs, of which 74 were classified as epileptic, representing two extended families were subjected to a genome-wide linkage scan using 410 microsatellite markers yielding informative coverage averaging 5.95 +/- 0.21 Mb. Though previous studies based on pedigree analyses proposed a major gene of influence, the present study demonstrated the trait to be highly polygenic. Studies of complex disorders in humans indicate that a liberal composite evaluation of genetic linkage is needed to identify underlying quantitative trait loci (QTLs). Four chromosomes yielded tentative linkage based upon LOD scores in excess of 1.0. Possible QTLs within these regions were supported also by analyses of multipoint linkage, allele frequency, TDT, and transmission of haplotype blocks.ConclusionsTaken together the data tentatively indicate six QTLs, three on CFA 2, and one on each of CFA 6, 12, and 37, that support fine mapping for mutations associated with epilepsy in the Belgian shepherd. The study also underscores the complexity of genomic linkage studies for polygenic disorders
Spin-injection through an Fe/InAs Interface
The spin-dependence of the interface resistance between ferromagnetic Fe and
InAs is calculated from first-principles for specular and disordered (001)
interfaces. Because of the symmetry mismatch in the minority-spin channel, the
specular interface acts as an efficient spin filter with a transmitted current
polarisation between 98 an 89%.
The resistance of a specular interface in the diffusive regime is comparable
to the resistance of a few microns of bulk InAs.
Symmetry-breaking arising from interface disorder reduces the spin asymmetry
substantially and we conclude that efficient spin injection from Fe into InAs
can only be realized using high quality epitaxial interfaces.Comment: 4 pages, 4 figure
Quenching of Spin Hall Effect in Ballistic nano-junctions
We show that a nanometric four-probe ballistic junction can be used to check
the presence of a transverse spin Hall current in a system with a Spin Orbit
coupling not of the Rashba type, but rather due to the in-plane electric field.
Indeed, the spin Hall effect is due to the presence of an effective small
transverse magnetic field corresponding to the Spin Orbit coupling generated by
the confining potential. The strength of the field and the junction shape
characterize the quenching Hall regime, usually studied by applying
semi-classical approaches. We discuss how a quantum mechanical relativistic
effect, such as the Spin Orbit one, can be observed in a low energy system and
explained by using classical mechanics techniques.Comment: 5 pages, 4 figures, PACS: 72.25.-b, 72.20.My, 73.50.Jt, to appear in
Phys. Rev.
Healthiness from Duality
Healthiness is a good old question in program logics that dates back to
Dijkstra. It asks for an intrinsic characterization of those predicate
transformers which arise as the (backward) interpretation of a certain class of
programs. There are several results known for healthiness conditions: for
deterministic programs, nondeterministic ones, probabilistic ones, etc.
Building upon our previous works on so-called state-and-effect triangles, we
contribute a unified categorical framework for investigating healthiness
conditions. We find the framework to be centered around a dual adjunction
induced by a dualizing object, together with our notion of relative
Eilenberg-Moore algebra playing fundamental roles too. The latter notion seems
interesting in its own right in the context of monads, Lawvere theories and
enriched categories.Comment: 13 pages, Extended version with appendices of a paper accepted to
LICS 201
The search for novel analgesics: re-examining spinal cord circuits with new tools
In this perspective, we propose the absence of detailed information regarding spinal cord
circuits that process sensory information remains a major barrier to advancing analgesia.
We highlight recent advances showing that functionally discrete populations of neurons in
the spinal cord dorsal horn play distinct roles in processing sensory information. We then
discuss new molecular, electrophysiological, and optogenetic techniques that can be
employed to understand how dorsal horn circuits process tactile and nociceptive
information. We believe this information can drive the development of entirely new classes
of pharmacotherapies that target key elements in spinal circuits to selectively modify
sensory function and blunt pain
Single-, Dual- and Triple-band Frequency Reconfigurable Antenna
The paper presents a frequency reconfigurable slot dipole antenna. The antenna is capable of being switched between single-band, dual-band or triple-band operation. The antenna incorporates three pairs of pin-diodes which are located within the dipole arms. The antenna was designed to operate at 2.4 GHz, 3.5 GHz and 5.2 GHz using the aid of CST Microwave Studio. The average measured gains are 1.54, 2.92 and 1.89 dBi for low, mid and high band respectively. A prototype was then constructed in order to verify the performance of the device. A good level of agreement was observed between simulation and measurement
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