61 research outputs found
STR loci D19S216, D20S502 and D20S842 analysis in the Serbian population using dentin DNA
Dentin provides a protective enclosure for genomic and mitochondrial DNA. In the present study, DNA was obtained from pulverized or ground teeth. The quality of the DNA extracted from the teeth of 70 unrelated individuals was tested in the context of assessing the allelic and genotypic frequencies of autosomal loci D19S216, D20S502 and D20S842, and calculating a number of parameters of population genetics and forensic interest. This study illustrates that teeth can be a convenient tissue to extract DNA from large numbers of individuals for population genetic studies as well as for forensic case work
PCR amplification of seven single copy nuclear genes from the Belgrade mummy
Here we report a DNA analysis of a human mummy dated approximately 2300 years BC. We extracted the DNA and used it for further PCR amplification of the following genes: c-fms proto-oncogene for CSF-1 receptor gene (CSF1PO); coagulation factor XIII a subunit gene (F13A01); c-fes/fps proto-oncogene (FESFPS); tyrosine hydroxylase gene (TH01); thyroid peroxidase gene (TPOX), von Willebrand factor gene (vWA) and Y chromosome specific sequence. The alleles from Belgrade mummy do not differ from the most frequent alleles of all present human populations. The exception is FESFPS gene. Belgrade mummy is homozygous for this locus which contains alleles with 7 motif repeats while such allele is found in less than 0.38% of living humans.U ovom radu dati su rezultati analiza molekula DNK izolovanih iz uzorka mumije čoveka stare 2300 godina. Genomska DNK je izolovana i korišćena za PCR amplifikaciju sledećih gena: c-fms protoonkogen za CSF-l receptor gen (CSF1PO), gen za a subjedinicu humanog faktora koagulacije XIII (F13A01), c-fes/fps protoonkogen (FESFPS), gen za tirozin hidroksilazu (TH01), gen za tiroidnu peroksidazu (TROH), gen za von Willebrand-ov faktor(vWA) i specifične sekvence za Y hromozom. Aleli beogradske mumije se ne razlikuju od najučestalijih alela sadašanje humane populacije. Izuzetak je FESFPS gen. Beogradska mumija je homozigotna za ovaj lokus i ima alele sa motivom od 7 ponovaka. Učestalost ovog alela u današnjoj humanoj populaciji je manja od 0.38%.nul
Antiferromagnetic Excitations and Van Hove Singularities in YBaCuO
We show that in quasi-two-dimensional -wave superconductors Van Hove
singularities close to the Fermi surface lead to novel magnetic quasi-particle
excitations. We calculate the temperature and doping dependence of dynamical
magnetic susceptibility for YBCO and show that the proposed excitations are in
agreement with inelastic neutron scattering experiments. In addition, the
values of the gap parameter and in-plane antiferromagnetic coupling are much
smaller than usually believed.Comment: REVTeX, 4 pages + 3 PostScript (compressed) figures; to appear in
Phys. Rev. B (Rap. Comm.
Proximity effects at ferromagnet-superconductor interfaces
We study proximity effects at ferromagnet superconductor interfaces by
self-consistent numerical solution of the Bogoliubov-de Gennes equations for
the continuum, without any approximations. Our procedures allow us to study
systems with long superconducting coherence lengths. We obtain results for the
pair potential, the pair amplitude, and the local density of states. We use
these results to extract the relevant proximity lengths. We find that the
superconducting correlations in the ferromagnet exhibit a damped oscillatory
behavior that is reflected in both the pair amplitude and the local density of
states. The characteristic length scale of these oscillations is approximately
inversely proportional to the exchange field, and is independent of the
superconducting coherence length in the range studied. We find the
superconducting coherence length to be nearly independent of the ferromagnetic
polarization.Comment: 13 Pages total. Compressed .eps figs might display poorly, but will
print fin
Microscopic theory of weak pseudogap behavior in the underdoped cuprate superconductors I: General theory and quasiparticle properties
We derive in detail a novel solution of the spin fermion model which is valid
in the quasi-static limit pi T<<omega_sf, found in the intermediate
(pseudoscaling) regime of the magnetic phase diagram of cuprate
superconductors, and use it to obtain results for the temperature and doping
dependence of the single particle spectral density, the electron-spin
fluctuation vertex function, and the low frequency dynamical spin
susceptibility. The resulting strong anisotropy of the spectral density and the
vertex function lead to the qualitatively different behavior of_hot_ (around
k=(pi,0)) and_cold_ (around k=(pi/2,pi/2)) quasiparticles seen in ARPES
experiments. We find that the broad high energy features found in ARPES
measurements of the spectral density of the underdoped cuprate superconductors
are determined by strong antiferromagnetic (AF) correlations and incoherent
precursor effects of an SDW state, with reduced renormalized effective coupling
constant. The electron spin-fluctuation vertex function, i.e. the effective
interaction of low energy quasiparticles and spin degrees of freedom, is found
to be strongly anisotropic and enhanced for hot quasiparticles; the
corresponding charge-fluctuation vertex is considerably diminished. We thus
demonstrate that, once established, strong AF correlations act to reduce
substantially the effective electron-phonon coupling constant in cuprate
superconductors.Comment: REVTEX with EPS figures, uses multicol.sty, epsfig,sty, psfig.st
Proximity effects and characteristic lengths in ferromagnet-superconductor structures
We present an extensive theoretical investigation of the proximity effects
that occur in Ferromagnet/Superconductor () systems. We use a numerical
method to solve self consistently the Bogoliubov-de Gennes equations in the
continuum. We obtain the pair amplitude and the local density of states (DOS),
and use these results to extract the relevant lengths characterizing the
leakage of superconductivity into the magnet and to study spin splitting into
the superconductor. These phenomena are investigated as a function of
parameters such as temperature, magnet polarization, interfacial scattering,
sample size and Fermi wavevector mismatch, all of which turn out to have
important influence on the results. These comprehensive results should help
characterize and analyze future data and are shown to be in agreement with
existing experiments.Comment: 24 pages, including 26 figure
Magnetoresistance of YBa2Cu3O7 in the "cold spots" model
We calculate the in-plane magnetoresistance of
YBaCuO in a magnetic field applied perpendicular to the
planes for the ``cold spots'' model. In this model, the electron relaxation
time at small regions on the Fermi surface near the
Brillouin zone diagonals is much longer than the relaxation time
at the rest of the Fermi surface ( is temperature). In
qualitative agreement with the experiment, we find that Kohler's rule is
strongly violated, but the ratio ,
where is the Hall angle, is approximately
temperature-independent. We find the ratio is about 5.5, which is of the same
order of magnitude as in the experiment.Comment: RevTeX, 4 pages, 6 figures. V.2: 2 references adde
A Self-Consistent Microscopic Theory of Surface Superconductivity
The electronic structure of the superconducting surface sheath in a type-II
superconductor in magnetic fields is calculated
self-consistently using the Bogoliubov-de Gennes equations. We find that the
pair potential exhibits pronounced Friedel oscillations near the
surface, in marked contrast with the results of Ginzburg-Landau theory. The
role of magnetic edge states is emphasized. The local density of states near
the surface shows a significant depletion near the Fermi energy due to the
development of local superconducting order. We suggest that this structure
could be unveiled by scanning-tunneling microscopy studies performed near the
edge of a superconducting sample.Comment: 12 pages, Revtex 3.0, 3 postscript figures appende
Superconducting gap node spectroscopy using nonlinear electrodynamics
We present a method to determine the nodal structure of the energy gap of
unconventional superconductors such as high materials. We show how
nonlinear electrodynamics phenomena in the Meissner regime, arising from the
presence of lines on the Fermi surface where the superconducting energy gap is
very small or zero, can be used to perform ``node spectroscopy'', that is, as a
sensitive bulk probe to locate the angular position of those lines. In
calculating the nonlinear supercurrent response, we include the effects of
orthorhombic distortion and plane anisotropy. Analytic results presented
demonstrate a systematic way to experimentally distinguish order parameters of
different symmetries, including cases with mixed symmetry (for example,
and ). We consider, as suggested by various experiments, order parameters
with predominantly -wave character, and describe how to determine the
possible presence of other symmetries. The nonlinear magnetic moment displays a
distinct behavior if nodes in the gap are absent but regions with small,
finite, values of the energy gap exist.Comment: 18 pages, Revtex, 9 postscript figures. Submitted to Phys. Rev
Effect of Magnetic field on the Pseudogap Phenomena in High-Tc Cuprates
We theoretically investigate the effect of magnetic field on the pseudogap
phenomena in High-Tc cuprates.
The obtained results well explain the experimental results including their
doping dependences.
In our previous paper (J. Phys. Soc. Jpn. 68 (1999) 2999.), we have shown
that the pseudogap phenomena observed in High-Tc cuprates are naturally
understood as a precursor of the strong coupling superconductivity. On the
other hand, there is an interpretation for the recent high field NMR
measurements to be an evidence denying the pairing scenarios for the pseudogap.
In this paper, we investigate the magnetic field dependence of NMR
on the basis of our formalism and show the interpretation to be inappropriate.
The results indicate that the value of the characteristic magnetic field
is remarkably large in case of the strong coupling
superconductivity, especially near the pseudogap onset temperature .
Therefore, the magnetic field dependences can not be observed and does
not vary when the strong pseudogap anomaly is observed. On the other hand,
is small in the comparatively weak coupling case and
varies when the weak pseudogap phenomena are observed.
These results properly explain the high magnetic field NMR experiments
continuously from under-doped to over-doped cuprates.
Moreover, we discuss the transport phenomena in the pseudogap phase. The
behaviors of the in-plane resistivity, the Hall coefficient and the c-axis
resistivity in the pseudogap phase are naturally understood by considering the
d-wave pseudogap
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