32,519 research outputs found
High Current Matching over Full-Swing and Low-Glitch Charge Pump Circuit for PLLs
A high current matching over full-swing and low-glitch charge pump (CP) circuit is proposed. The current of the CP is split into two identical branches having one-half the original current. The two branches are connected in source-coupled structure, and a two-stage amplifier is used to regulate the common-source voltage for the minimum current mismatch. The proposed CP is designed in TSMC 0.18µm CMOS technology with a power supply of 1.8 V. SpectreRF based simulation results show the mismatch between the current source and the current sink is less than 0.1% while the current is 40 µA and output swing is 1.32 V ranging from 0.2 V to 1.52 V. Moreover, the transient output current presents nearly no glitches. The simulation results verify the usage of the CP in PLLs with the maximum tuning range from the voltage-controlled oscillator, as well as the low power supply applications
Early Tracking Behavior in Small-field Quintessence Models
We study several quintessence models which are singular at Q=0, and use a
simple initial constraint to see when they enter
tracking regime, disregarding the details of inflation. We find it can give
strong constraints for the inverse power-law potential ,
which has to enter tracking regime for . While for the
supergravity model , the constraint is much
weakened. For another kind inverse power-law potential , it exhibits no constraints.Comment: 11 pages,5 figures. Improved versio
Alternative Supersymmetric Spectra
We describe the features of supersymmetric spectra, alternative to and
qualitatively different from that of most versions of the MSSM. The spectra are
motivated by extensions of the MSSM with an extra U(1)' gauge symmetry,
expected in many grand unified and superstring models, which provide a
plausible solution to the mu problem, both for models with supergravity and for
gauge-mediated supersymmetry breaking. Typically, many or all of the squarks
are rather heavy (larger than one TeV), especially for the first two families,
as are the sleptons in the supergravity models. However, there is a richer
spectrum of Higgs particles, neutralinos, and (possibly) charginos. Concrete
examples of such spectra are presented, and the phenomenological implications
are briefly discussed.Comment: 12 pages, LaTe
Identification of different types of kink modes in coronal loops: principles and application to TRACE results
We explore the possible observational signatures of different types of kink
modes (horizontal and vertical oscillations in their fundamental mode and
second harmonic) that may arise in coronal loops, with the aim of determining
how well the individual modes can be uniquely identified from time series of
images. A simple, purely geometrical model is constructed to describe the
different types of kink-mode oscillations. These are then `observed' from a
given direction. In particular, we employ the 3D geometrical parameters of 14
TRACE loops of transverse oscillations to try to identify the correct observed
wave mode. We find that for many combinations of viewing and loop geometry it
is not straightforward to distinguish between at least two types of kink modes
just using time series of images. We also considered Doppler signatures and
find that these can help obtain unique identifications of the oscillation modes
when employed in combination with imaging. We then compare the modeled spatial
signatures with the observations of 14 TRACE loops. We find that out of three
oscillations previously identified as fundamental horizontal mode oscillations,
two cases appear to be fundamental vertical mode oscillations (but possibly
combined with the fundamental horizontal mode), and one case appears to be a
combination of the fundamental vertical and horizontal modes, while in three
cases it is not possible to clearly distinguish between the fundamental mode
and the second-harmonic of the horizontal oscillation. In five other cases it
is not possible to clearly distinguish between a fundamental horizontal mode
and the second-harmonic of a vertical mode.Comment: 12 pages, 10 figures, 2 tables. A&A in pres
Functional analysis of the Arabidopsis TETRASPANIN gene family in plant growth and development
TETRASPANIN (TET) genes encode conserved integral membrane proteins that are known in animals to function in cellular communication during gamete fusion, immunity reaction and pathogen recognition. In plants, functional information is limited to one of the 17 members of the Arabidopsis TET gene family and to expression data in reproductive stages. Here, the promoter activity of all 17 Arabidopsis TET genes was investigated by pAtTET::NLS-GFP/GUS reporter lines throughout the life cycle, which predicted functional divergence in the paralogous genes per clade. However, partial overlap was observed for many TET genes across the clades, correlating with few phenotypes in single mutants and therefore requiring double mutant combinations for functional investigation. Mutational analysis showed a role for TET13 in primary root growth and lateral root development, and redundant roles for TET5 and TET6 in leaf and root growth through negative regulation of cell proliferation. Strikingly, a number of TET genes were expressed in embryonic and seedling progenitor cells and remained expressed until the differentiation state in the mature plant, suggesting a dynamic function over developmental stages. cis-regulatory elements together with transcription factor binding data provided molecular insight into the site, conditions and perturbations that affect TET gene expression, and positioned the TET genes in different molecular pathways; the data represent a hypothesis-generating resource for further functional analyses
Experimental Observation of Classical Sub-Wavelength Interference with Thermal-Like Light
We show the experimental observation of the classical sub-wavelength
double-slit interference with a pseudo-thermal light source. The experimental
results are in agreement with the recent theoretical prediction shown in
quant-ph/0404078 (to be appeared in Phys. Rev. A).Comment: 4 pages, 6 figure
Angular Momentum Mixing in Single Flavor Color Superconductivity with Transverse Pairing
Because of the equal strength of the pairing potential mediated by one-gluon
exchange for all partial waves to the leading order QCD running coupling
constant and the nonlinearity of the gap equation, the non-spherical pairing in
single flavor color superconductivity(CSC) can not be restricted in a single
non-s-wave channel and the mixing among different angular momenta will occur.
In this paper, we examine the angular momentum mixing in single flavor CSC with
transverse pairing, in which the pairing quarks have opposite helicity. We find
that the free energy of all non-spherical pairing states are lowered by angular
momentum mixing compared with that contain p-wave only. But the amount of the
free energy drop is numerically small. Consequently the most stable pairing
state that respect the time reversal invariance remains the spherical CSL.Comment: 16 pages, 2 figures, 1 table in Revte
Spatial Interference: From Coherent To Incoherent
It is well known that direct observation of interference and diffraction
pattern in the intensity distribution requires a spatially coherent source.
Optical waves emitted from portions beyond the coherence area possess
statistically independent phases, and will degrade the interference pattern. In
this paper we show an optical interference experiment, which seems contrary to
our common knowledge, that the formation of the interference pattern is related
to a spatially incoherent light source. Our experimental scheme is very similar
to Gabor's original proposal of holography[1], just with an incoherent source
replacing the coherent one. In the statistical ensemble of the incoherent
source, each sample field produces a sample interference pattern between object
wave and reference wave. These patterns completely differ from each other due
to the fluctuation of the source field distribution. Surprisingly, the sum of a
great number of sample patterns exhibits explicitly an interference pattern,
which contains all the information of the object and is equivalent to a
hologram in the coherent light case. In this sense our approach would be
valuable in holography and other interference techniques for the case where
coherent source is unavailable, such as x-ray and electron sources.Comment: 8 pages, 5 figure
Centrality, system size and energy dependences of charged-particle pseudo-rapidity distribution
Utilizing the three-fireball picture within the quark combination model, we
study systematically the charged particle pseudorapidity distributions in both
Au+Au and Cu+Cu collision systems as a function of collision centrality and
energy, 19.6, 62.4, 130 and 200 GeV, in full pseudorapidity
range. We find that: (i)the contribution from leading particles to
distributions increases with the decrease of the collision
centrality and energy respectively; (ii)the number of the leading particles is
almost independent of the collision energy, but it does depend on the nucleon
participants ; (iii)if Cu+Cu and Au+Au collisions at the same
collision energy are selected to have the same , the resulting of
charged particle distributions are nearly identical, both in the
mid-rapidity particle density and the width of the distribution. This is true
for both 62.4 GeV and 200 GeV data. (iv)the limiting fragmentation phenomenon
is reproduced. (iiv) we predict the total multiplicity and pseudorapidity
distribution for the charged particles in Pb+Pb collisions at TeV. Finally, we give a qualitative analysis of the
and as function of
and from RHIC to LHC.Comment: 12 pages, 8 figure
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