38,650 research outputs found
Seven-fluorochrome mouse M-FISH for high-resolution analysis of interchromosomal rearrangements
The mouse has evolved to be the primary mammalian genetic model organism. Important applications include the modeling of human cancer and cloning experiments. In both settings, a detailed analysis of the mouse genome is essential. Multicolor karyotyping technologies have emerged to be invaluable tools for the identification of mouse chromosomes and for the deciphering of complex rearrangements. With the increasing use of these multicolor technologies resolution limits are critical. However, the traditionally used probe sets, which employ 5 different fluorochromes, have significant limitations. Here, we introduce an improved labeling strategy. Using 7 fluorochromes we increased the sensitivity for the detection of small interchromosomal rearrangements (700 kb or less) to virtually 100%. Our approach should be important to unravel small interchromosomal rearrangements in mouse models for DNA repair defects and chromosomal instability. Copyright (C) 2003 S. Karger AG, Basel
High-resolution wide-band Fast Fourier Transform spectrometers
We describe the performance of our latest generations of sensitive wide-band
high-resolution digital Fast Fourier Transform Spectrometer (FFTS). Their
design, optimized for a wide range of radio astronomical applications, is
presented. Developed for operation with the GREAT far infrared heterodyne
spectrometer on-board SOFIA, the eXtended bandwidth FFTS (XFFTS) offers a high
instantaneous bandwidth of 2.5 GHz with 88.5 kHz spectral resolution and has
been in routine operation during SOFIA's Basic Science since July 2011. We
discuss the advanced field programmable gate array (FPGA) signal processing
pipeline, with an optimized multi-tap polyphase filter bank algorithm that
provides a nearly loss-less time-to-frequency data conversion with
significantly reduced frequency scallop and fast sidelobe fall-off. Our digital
spectrometers have been proven to be extremely reliable and robust, even under
the harsh environmental conditions of an airborne observatory, with
Allan-variance stability times of several 1000 seconds. An enhancement of the
present 2.5 GHz XFFTS will duplicate the number of spectral channels (64k),
offering spectroscopy with even better resolution during Cycle 1 observations.Comment: Accepted for publication in A&A (SOFIA/GREAT special issue
The Universal Rotation Curve of Spiral Galaxies. II The Dark Matter Distribution out to the Virial Radius
In the current LambdaCDM cosmological scenario, N-body simulations provide us
with a Universal mass profile, and consequently a Universal equilibrium
circular velocity of the virialized objects, as galaxies. In this paper we
obtain, by combining kinematical data of their inner regions with global
observational properties, the Universal Rotation Curve (URC) of disk galaxies
and the corresponding mass distribution out to their virial radius. This curve
extends the results of Paper I, concerning the inner luminous regions of Sb-Im
spirals, out to the edge of the galaxy halos.Comment: In press on MNRAS. 10 pages, 8 figures. The Mathematica code for the
figures is available at: http://www.novicosmo.org/salucci.asp Corrected typo
Fractal extra dimension in Kaluza-Klein theory
Kaluza-Klein theory in which the geometry of an additional dimension is
fractal has been considered. In such a theory the mass of an elementary
electric charge appears to be many orders of magnitude smaller than the Planck
mass, and the "tower" of masses which correspond to higher integer charges
becomes aperiodic.Comment: 3 pages, accepted for publication in Phys.Rev.D (submitted on
3.28.2001
Determination of the resistivity anisotropy of SrRuO by measuring the planar Hall effect
We have measured the planar Hall effect in epitaxial thin films of the
itinerant ferromagnet SrRuO3 patterned with their current paths at different
angles relative to the crystallographic axes. Based on the results, we have
determined that SrRuO3 exhibits small resistivity anisotropy in the entire
temperature range of our measurements (between 2 to 300 K); namely, both above
and below its Curie temperature (~150 K). It means that in addition to
anisotropy related to magnetism, the resistivity anisotropy of SrRuO3 has an
intrinsic, nonmagnetic source. We have found that the two sources of anisotropy
have competing effects
Antivortices due to competing orbital and paramagnetic pair-breaking effects
Thermodynamically stable vortex-antivortex structures in a
quasi-two-dimensional superconductor in a tilted magnetic field are predicted.
For this geometry, both orbital and spin pair-breaking effects exist, with
their relative strength depending on the tilt angle \Theta. The spectrum of
possible states contains as limits the ordinary vortex state (for large \Theta)
and the Fulde-Ferrell-Larkin-Ovchinnikov state (for \Theta=0). The
quasiclassical equations are solved near H_{c2} for arbitrary \Theta and it is
shown that stable states with coexisting vortices and antivortices exist in a
small interval close to \Theta=0. The results are compared with recent
predictions of antivortices in mesoscopic samples.Comment: 11 pages, 3 figure
On Dimensional Degression in AdS(d)
We analyze the pattern of fields in d+1 dimensional anti-de Sitter space in
terms of those in d dimensional anti-de Sitter space. The procedure, which is
neither dimensional reduction nor dimensional compactification, is called
dimensional degression. The analysis is performed group-theoretically for all
totally symmetric bosonic and fermionic representations of the anti-de Sitter
algebra. The field-theoretical analysis is done for a massive scalar field in
AdS(d+d) and massless spin one-half, spin one, and spin two fields in
AdS(d+1). The mass spectra of the resulting towers of fields in AdS(d) are
found. For the scalar field case, the obtained results extend to the shadow
sector those obtained by Metsaev in [1] by a different method.Comment: 30 page
Persistence of characteristics of an ordered flux line lattice above the second peak in
We report Small Angle Neutron Scattering measurements of the flux lines
lattice (FLL) in . As previously reported, the
scattered intensity decreases strongly when the magnetic field is increased,
but it remains measurable far above the second peak. The direct observation of
Bragg peaks proves that the characteristics of a lattice are still present. No
structural features related to a symmetry breaking, such as a liquid like or an
amorphous state, can be observed. However, the associated scattered intensity
is very low and is difficult to explain. We discuss the coexistence between two
FLL states as a possible interpretation.Comment: accepted for publication in Phys Rev
Foundations of self-consistent particle-rotor models and of self-consistent cranking models
The Kerman-Klein formulation of the equations of motion for a nuclear shell
model and its associated variational principle are reviewed briefly. It is then
applied to the derivation of the self-consistent particle-rotor model and of
the self-consistent cranking model, for both axially symmetric and triaxial
nuclei. Two derivations of the particle-rotor model are given. One of these is
of a form that lends itself to an expansion of the result in powers of the
ratio of single-particle angular momentum to collective angular momentum, that
is essentual to reach the cranking limit. The derivation also requires a
distinct, angular-momentum violating, step. The structure of the result implies
the possibility of tilted-axis cranking for the axial case and full
three-dimensional cranking for the triaxial one. The final equations remain
number conserving. In an appendix, the Kerman-Klein method is developed in more
detail, and the outlines of several algorithms for obtaining solutions of the
associated non-linear formalism are suggested.Comment: 29 page
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