5,023 research outputs found
A stationary free boundary problem modeling electrostatic MEMS
A free boundary problem describing small deformations in a membrane based
model of electrostatically actuated MEMS is investigated. The existence of
stationary solutions is established for small voltage values. A justification
of the widely studied narrow-gap model is given by showing that steady state
solutions of the free boundary problem converge toward stationary solutions of
the narrow-gap model when the aspect ratio of the device tends to zero
Functional reassembly of the anion transport domain of human red cell band 3 (AE1) from multiple and non-complementary fragments
AbstractWe constructed cDNA clones encoding N-terminal, C-terminal and internal polypeptide fragments of the human red cell anion exchanger (band 3; AE1). The internal fragments comprised between one and seven putative transmembrane spans with two or more spans deleted from both termini of the membrane domain of band 3. Sets of three, four or five complementary fragments, which together represented the complete amino acid sequence of the membrane domain, were co-expressed in Xenopus oocytes. Stilbene disulphonate-sensitive chloride uptake assays revealed that all six of the three-fragment combinations and two of the four-fragment combinations reassembled functionally in vivo. Unexpectedly, co-expression of a non-complementary pair of fragments comprising the first five and last seven putative transmembrane spans (i.e. entirely lacking spans six and seven) was also found to be sufficient to generate stilbene disulphonate-sensitive chloride uptake
An 11b pipeline ADC with dual sampling technique for converting multi-carrier signals
This paper presents a dual sampling technique for analog-to-digital converters (ADCs) to convert multi-carrier signals more efficiently and proposes an 11b switched-capacitor pipeline ADC based on this technique. With the dual sampling technique, the input signal power of the ADC can be boosted without getting excessive clipping noise and the ADC can have a higher resolution over the critical low amplitude region. Hence the overall signal to thermal, quantization and clipping noise ratio is improved. The 11b pipeline ADC with the proposed technique achieves a wide input signal range of 2Vppd using a single 1.2V supply. Simulations show an improvement of about 5dB in SNDR and better than 10dB in MTPR compared to a conventional 11b ADC for converting multi-carrier signals
Incumbent heterogeneity in creative destruction: a study of three Dutch newspaper organisations
With a study of three Dutch newspaper organisations, we identify four dimensions along which incumbent response to discontinuous change may differ: response timing (early or late), size of commitment to the new business (big or small), progression of commitment to the new business (continuous or intermittent), and approaches to bridging the capability gap (internal development, strategic alliance, or acquisition). These response strategies are neither mutually exclusive nor static, and their relative focus differs over time as well as across incumbents. Such inter-temporal and cross-sectional variations in response strategies are influenced by various incumbent-specific characteristics and shaped by interrelated contingencies internal or external to incumbents
Outer Regions of the Milky Way
With the start of the Gaia era, the time has come to address the major
challenge of deriving the star formation history and evolution of the disk of
our MilkyWay. Here we review our present knowledge of the outer regions of the
Milky Way disk population. Its stellar content, its structure and its dynamical
and chemical evolution are summarized, focussing on our lack of understanding
both from an observational and a theoretical viewpoint. We describe the
unprecedented data that Gaia and the upcoming ground-based spectroscopic
surveys will provide in the next decade. More in detail, we quantify the expect
accuracy in position, velocity and astrophysical parameters of some of the key
tracers of the stellar populations in the outer Galactic disk. Some insights on
the future capability of these surveys to answer crucial and fundamental issues
are discussed, such as the mechanisms driving the spiral arms and the warp
formation. Our Galaxy, theMilkyWay, is our cosmological laboratory for
understanding the process of formation and evolution of disk galaxies. What we
learn in the next decades will be naturally transferred to the extragalactic
domain.Comment: 22 pages, 10 figures, Invited review, Book chapter in "Outskirts of
Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and
Space Science Library, Springer, in pres
The correction of the littlest Higgs model to the Higgs production process in collisions
The littlest Higgs model is the most economical one among various little
Higgs models. In the context of the littlest Higgs(LH) model, we study the
process and calculate the contributions of the
LH model to the cross section of this process. The results show that, in most
of parameter spaces preferred by the electroweak precision data, the value of
the relative correction is larger than 10%. Such correction to the process
is large enough to be detected via
collisions in the future high energy linear collider()
experiment with the c.m energy =500 GeV and a yearly integrated
luminosity , which will give an ideal way to test the
model.Comment: 13 pages, 4 figure
The State of Self-Organized Criticality of the Sun During the Last 3 Solar Cycles. I. Observations
We analyze the occurrence frequency distributions of peak fluxes , total
fluxes , and durations of solar flares over the last three solar cycles
(during 1980--2010) from hard X-ray data of HXRBS/SMM, BATSE/CGRO, and RHESSI.
From the synthesized data we find powerlaw slopes with mean values of
for the peak flux, for the total
flux, and for flare durations. We find a systematic
anti-correlation of the powerlaw slope of peak fluxes as a function of the
solar cycle, varying with an approximate sinusoidal variation
, with a
mean of , a variation of , a solar cycle
period yrs, and a cycle minimum time . The
powerlaw slope is flattest during the maximum of a solar cycle, which indicates
a higher magnetic complexity of the solar corona that leads to an
overproportional rate of powerful flares.Comment: subm. to Solar Physic
N=4 SYM on R x S^3 and Theories with 16 Supercharges
We study N=4 SYM on R x S^3 and theories with 16 supercharges arising as its
consistent truncations. These theories include the plane wave matrix model, N=4
SYM on R x S^2 and N=4 SYM on R x S^3/Z_k, and their gravity duals were studied
by Lin and Maldacena. We make a harmonic expansion of the original N=4 SYM on R
x S^3 and obtain each of the truncated theories by keeping a part of the
Kaluza-Klein modes. This enables us to analyze all the theories in a unified
way. We explicitly construct some nontrivial vacua of N=4 SYM on R x S^2. We
perform 1-loop analysis of the original and truncated theories. In particular,
we examine states regarded as the integrable SO(6) spin chain and a
time-dependent BPS solution, which is considered to correspond to the AdS giant
graviton in the original theory.Comment: 68 pages, 12 figures, v2,v3:typos corrected and comments added. To
appear in JHE
Wave scattering from self-affine surfaces
Electromagnetic wave scattering from a perfectly reflecting self-affine
surface is considered. Within the framework of the Kirchhoff approximation, we
show that the scattering cross section can be exactly written as a function of
the scattering angle via a centered symmetric Levy distribution for general
roughness amplitude, Hurst exponent and wavelength of the incident wave. The
amplitude of the specular peak, its width and its position are discussed as
well as the power law decrease (with scattering angle) of the scattering cross
section.Comment: RevTeX, 4 pages including 2 figures. Submitted Phys. Rev. Let
The association of physical activity and progression of knee cartilage T2 relaxation time with 3 Tesla MRI over a period of 4 years using data from the osteoarthritis initiative
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