6,543 research outputs found
Purification and Characterization of p68/70, Regeneration-Associated Proteins from Goldfish Brain
Two acidic proteins (p68/70) previously shown to be associated with regeneration of the goldfish optic nerve were purified 887-fold from brain homogenates of Carassius auratus. Purification to homogeneity was achieved by sequential chromatography of a 100,000 g brain supernatant fraction on DEAE-Sephacel, Cu 2+ -charged iminodiacetic acid agarose, and gel filtration. The Stokes radius of the doublet was determined to be 5.8 nm, and the sedimentation coefficient calculated to be 5 2. From these values a molecular mass of 128 kDa and a frictional coefficient ratio of 1.6 were calculated. Chromatofocusing on a high-resolution DEAE column resolved the protein doublet into three dimeric species of p68, p68/70, and p70. These results indicate that the proteins are highly elongated and associate as homodimers or as a hetero-dimer. Subcellular localization and membrane extraction experiments indicated p68/70 to be a component of the plasma membrane associated primarily through hydro-phobic interactions. p68/70 demonstrated biphasic behavior in phase partition experiments using Triton 114. Analysis of hydrolytic products indicated p68/70 to be a glyco-protein, containing 11% carbohydrate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65206/1/j.1471-4159.1994.62031182.x.pd
Two-body non-leptonic decays on the lattice
We show that, under reasonable hypotheses, it is possible to study two-body
non-leptonic weak decays in numerical simulations of lattice QCD. By assuming
that final-state interactions are dominated by the nearby resonances and that
the couplings of the resonances to the final particles are smooth functions of
the external momenta, it is possible indeed to overcome the difficulties
imposed by the Maiani-Testa no-go theorem and to extract the weak decay
amplitudes, including their phases. Under the same assumptions, results can be
obtained also for time-like form factors and quasi-elastic processes.Comment: 15 pages, 1 Postscript figur
Generation of DNA Oligomers with Similar Chemical Kinetics via in-silico Optimization
Networks of interacting DNA oligomers are useful for applications such as biomarker detection, targeted drug delivery, information storage, and photonic information processing. However, differences in the chemical kinetics of hybridization reactions, referred to as kinetic dispersion, can be problematic for some applications. Here, it is found that limiting unnecessary stretches of Watson-Crick base pairing, referred to as unnecessary duplexes, can yield exceptionally low kinetic dispersions. Hybridization kinetics can be affected by unnecessary intra-oligomer duplexes containing only 2 base-pairs, and such duplexes explain up to 94% of previously reported kinetic dispersion. As a general design rule, it is recommended that unnecessary intra-oligomer duplexes larger than 2 base-pairs and unnecessary inter-oligomer duplexes larger than 7 base-pairs be avoided. Unnecessary duplexes typically scale exponentially with network size, and nearly all networks contain unnecessary duplexes substantial enough to affect hybridization kinetics. A new method for generating networks which utilizes in-silico optimization to mitigate unnecessary duplexes is proposed and demonstrated to reduce in-vitro kinetic dispersions as much as 96%. The limitations of the new design rule and generation method are evaluated in-silico by creating new oligomers for several designs, including three previously programmed reactions and one previously engineered structure
A neuropsychological instrument measuring age-related cerebral decline in older drivers: development, reliability, and validity of MedDrive.
When facing age-related cerebral decline, older adults are unequally affected by cognitive impairment without us knowing why. To explore underlying mechanisms and find possible solutions to maintain life-space mobility, there is a need for a standardized behavioral test that relates to behaviors in natural environments. The aim of the project described in this paper was therefore to provide a free, reliable, transparent, computer-based instrument capable of detecting age-related changes on visual processing and cortical functions for the purposes of research into human behavior in computational transportation science. After obtaining content validity, exploring psychometric properties of the developed tasks, we derived (Study 1) the scoring method for measuring cerebral decline on 106 older drivers aged â„70 years attending a driving refresher course organized by the Swiss Automobile Association to test the instrument's validity against on-road driving performance (106 older drivers). We then validated the derived method on a new sample of 182 drivers (Study 2). We then measured the instrument's reliability having 17 healthy, young volunteers repeat all tests included in the instrument five times (Study 3) and explored the instrument's psychophysical underlying functions on 47 older drivers (Study 4). Finally, we tested the instrument's responsiveness to alcohol and effects on performance on a driving simulator in a randomized, double-blinded, placebo, crossover, dose-response, validation trial including 20 healthy, young volunteers (Study 5). The developed instrument revealed good psychometric properties related to processing speed. It was reliable (ICC = 0.853) and showed reasonable association to driving performance (R (2) = 0.053), and responded to blood alcohol concentrations of 0.5 g/L (p = 0.008). Our results suggest that MedDrive is capable of detecting age-related changes that affect processing speed. These changes nevertheless do not necessarily affect driving behavior
Clustering in mixing flows
We calculate the Lyapunov exponents for particles suspended in a random
three-dimensional flow, concentrating on the limit where the viscous damping
rate is small compared to the inverse correlation time. In this limit Lyapunov
exponents are obtained as a power series in epsilon, a dimensionless measure of
the particle inertia. Although the perturbation generates an asymptotic series,
we obtain accurate results from a Pade-Borel summation. Our results prove that
particles suspended in an incompressible random mixing flow can show pronounced
clustering when the Stokes number is large and we characterise two distinct
clustering effects which occur in that limit.Comment: 5 pages, 1 figur
Thermodynamics of ideal quantum gas with fractional statistics in D dimensions
We present exact and explicit results for the thermodynamic properties
(isochores, isotherms, isobars, response functions, velocity of sound) of a
quantum gas in dimensions D>=1 and with fractional exclusion statistics 0<=g<=1
connecting bosons (g=0) and fermions (g=1). In D=1 the results are equivalent
to those of the Calogero-Sutherland model. Emphasis is given to the crossover
between boson-like and fermion-like features, caused by aspects of the
statistical interaction that mimic long-range attraction and short-range
repulsion. The full isochoric heat capacity and the leading low-T term of the
isobaric expansivity in D=2 are independent of g. The onset of Bose-Einstein
condensation along the isobar occurs at a nonzero transition temperature in all
dimensions. The T-dependence of the velocity of sound is in simple relation to
isochores and isobars. The effects of soft container walls are accounted for
rigorously for the case of a pure power-law potential.Comment: 15 pages, 31 figure
Toll-like receptor 3 activation is required for normal skin barrier repair following UV damage.
UV damage to the skin leads to the release of noncoding RNA (ncRNA) from necrotic keratinocytes that activates Toll-like receptor 3 (TLR3). This release of ncRNA triggers inflammation in the skin following UV damage. Recently, TLR3 activation was also shown to aid wound repair and increase the expression of genes associated with permeability barrier repair. Here, we sought to test whether skin barrier repair after UVB damage is dependent on the activation of TLR3. We observed that multiple ncRNAs induced expression of skin barrier repair genes, that the TLR3 ligand Poly (I:C) also induced expression and function of tight junctions, and that the ncRNA U1 acts in a TLR3-dependent manner to induce expression of skin barrier repair genes. These observations were shown to have functional relevance as Tlr3-/- mice displayed a delay in skin barrier repair following UVB damage. Combined, these data further validate the conclusion that recognition of endogenous RNA by TLR3 is an important step in the program of skin barrier repair
Automata learning algorithms and processes for providing more complete systems requirements specification by scenario generation, CSP-based syntax-oriented model construction, and R2D2C system requirements transformation
Systems, methods and apparatus are provided through which in some embodiments, automata learning algorithms and techniques are implemented to generate a more complete set of scenarios for requirements based programming. More specifically, a CSP-based, syntax-oriented model construction, which requires the support of a theorem prover, is complemented by model extrapolation, via automata learning. This may support the systematic completion of the requirements, the nature of the requirement being partial, which provides focus on the most prominent scenarios. This may generalize requirement skeletons by extrapolation and may indicate by way of automatically generated traces where the requirement specification is too loose and additional information is required
Taxonomy of particles in Ising spin chains
The statistical mechanics of particles with shapes on a one-dimensional
lattice is investigated in the context of the Ising chain with uniform
nearest-neighbor coupling, quadratic single-site potential, and magnetic field,
which supports four distinct ground states:
, ,
, . The complete
spectrum is generated from each ground state by particles from a different set
of six or seven species. Particles and elements of pseudo-vacuum are
characterized by motifs (patterns of several consecutive site variables).
Particles are floating objects that can be placed into open slots on the
lattice. Open slots are recognized as permissible links between motifs. The
energy of a particle varies between species but is independent of where it is
placed. Placement of one particle changes the open-slot configuration for
particles of all species. This statistical interaction is encoded in a
generalized Pauli principle, from which the multiplicity of states for a given
particle combination is determined and used for the exact statistical
mechanical analysis. Particles from all species belong to one of four
categories: compacts, hosts, tags, or hybrids. Compacts and hosts find open
slots in segments of pseudo-vacuum. Tags find open slots inside hosts. Hybrids
are tags with hosting capability. In the taxonomy of particles proposed here,
`species' is indicative of structure and `category' indicative of function. The
hosting function splits the Pauli principle into exclusion and accommodation
parts. Near phase boundaries, the state of the Ising chain at low temperature
is akin to that of miscible or immiscible liquids with particles from one
species acting as surfactant molecules.Comment: 12 pages, 6 tables, 6 figure
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