4,536 research outputs found
Variation of Electrostatic Coupling and Investigation of Current Percolation Paths in Nanocrystalline Silicon Cross Transistors
Nanocrystalline silicon thin films are promising materials for the development of advanced Large Scale Integration compatible quantum-dot and single-electron charging devices. The films consist of nanometer-scale grains of crystalline silicon, separated by amorphous silicon or silicon dioxide grain boundaries up to a few nanometer thick. These films have been used to fabricate single-electron transistor and memory devices, where the grains form single-electron charging islands isolated by tunnel barriers formed by the grain boundaries. The grain boundary tunnel barrier isolating the grains is also of great importance, as this determines the extent of the electrostatic and tunnel coupling between different grains. These effects can lead to the nanocrystalline silicon thin film behaving as a system of coupled quantum dots.& more..
The a-number of hyperelliptic curves
It is known that for a smooth hyperelliptic curve to have a large -number,
the genus must be small relative to the characteristic of the field, ,
over which the curve is defined. It was proven by Elkin that for a genus
hyperelliptic curve to have , the genus is bounded by
. In this paper, we show that this bound can be lowered to . The method of proof is to force the Cartier-Manin matrix to have rank one
and examine what restrictions that places on the affine equation defining the
hyperelliptic curve. We then use this bound to summarize what is known about
the existence of such curves when and .Comment: 7 pages. v2: revised and improved the proof of the main theorem based
on suggestions from the referee. To appear in the proceedings volume of Women
in Numbers Europe-
STM/STS Study on 4a X 4a Electronic Charge Order of Superconducting Bi2Sr2CaCu2O8+d
We performed low-bias STM measurements on underdoped Bi2212 crystals, and
confirmed that a two-dimensional (2D) superstructure with a periodicity of four
lattice constants (4a) is formed within the Cu-O plane at T<Tc. This 4a X 4a
superstructure, oriented along the Cu-O bonding direction, is nondispersive and
more intense in lightly doped samples with a zero temperature pseudogap (ZTPG)
than in samples with a d-wave gap. The nondispersive 4a X 4a superstructure was
clearly observed within the ZTPG or d-wave gap, while it tended to fade out
outside the gaps. The present results provide a useful test for various models
proposed for an electronic order hidden in the underdoped region of high-Tc
cuprates.Comment: 4 pages, submitted to J. Phys. Soc. Jp
J/psi production at RHIC-PHENIX
The J/psi is considered to be among the most important probes for the
deconfined quark gluon plasma (QGP) created by relativistic heavy ion
collisions. While the J/psi is thought to dissociate in the QGP by Debye color
screening, there are competing effects from cold nuclear matter (CNM),
feed-downs from excited charmonia (chi_c and psi') and bottom quarks, and
regeneration from uncorrelated charm quarks. Measurements that can provide
information to disentangle these effects are presented in this paper.Comment: 4 pages, 3 figures, conference proceedings: the 20th International
Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Quark Matter
2008, Jaipur (India), 4-10 February 2008, submitted to J. Phys. G: Nuclear
and Particle Physic
Consumer Banking and Credit Risk
Following Jara and Oda (2007), we consider a group of Chilean banks specializing in consumer loans. Taking the dynamics of the group as a whole, we propose a credit risk model that is based on loan loss provisions. Using accounting ratios, we show that a model for this purpose is dynamic and highly non-linear. Our empirical results show that the banking aggregates loan loss provisions, write-offs, and total loans can be modelled for this group of banks using a small number of macroeconomics variables. Actually, we conclude that the output gap is a strong factor in the model, and that the model performs well when only this external factor is considered.
Geometry of Reduced Supersymmetric 4D Yang-Mills Integrals
We study numerically the geometric properties of reduced supersymmetric
non-compact SU(N) Yang-Mills integrals in D=4 dimensions, for N = 2,3, ..., 8.
We show that in the range of large eigenvalues of the matrices A^mu, the
original D-dimensional rotational symmetry is spontaneously broken and the
dominating field configurations become one-dimensional, as anticipated by
studies of the underlying surface theory. We also discuss possible implications
of our results for the IKKT model.Comment: 14 pages, Latex + 3 eps fig., a comment added to the conclusion
Supply and Demand Identification in the Credit Market
This paper identifies supply and demand functions in the Chilean credit market. The analysis divides credit into three categories by debtor type, namely consumption, commercial and housing loans. We successfully exploit novel bank-level data on non-price covenants to address the simultaneous equation endogeneity problem in the estimation of interest rate elasticities. Our truly unique panel data set covers the 2003-2009 period and combines information on loan amount allocation, interest rates, balance sheet indicators with information from the “Survey on General Conditions and Standards in the Credit Market”, conducted by the Central Bank of Chile since 2003. Additionally, we characterize the statistical determinants of the survey responses, and later we use our estimation results for understanding the credit contraction episode of the second half of 2008, during the global financial turmoil.
Rotated stripe order and its competition with superconductivity in LaSrCuO
We report the observation of a bulk charge modulation in
LaSrCuO (LSCO) with a characteristic in-plane wave-vector
of (0.236, ), with =0.011 r.l.u. The transverse shift of
the ordering wave-vector indicates the presence of rotated charge-stripe
ordering, demonstrating that the charge ordering is not pinned to the Cu-O bond
direction. On cooling through the superconducting transition, we find an abrupt
change in the growth of the charge correlations and a suppression of the charge
order parameter indicating competition between the two orderings. Orthorhombic
LSCO thus helps bridge the apparent disparities between the behavior previously
observed in the tetragonal "214" cuprates and the orthorhombic yttrium and
bismuth-based cuprates and thus lends strong support to the idea that there is
a common motif to charge order in all cuprate families.Comment: 6 pages, 4 figue
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