380 research outputs found
Preparation of γ-di-tertiary Glycols From the Esters of γ-keto Carboxylic Acids. II
Some Y-di-tertiary glycols have been prepared by the Grignard\u27s method from the Et esters of y-keto carboxylic acids
Preparation of γ-di-tertiary Glycols From the Esters of γ-keto Carboxylic Acids. II
Some Y-di-tertiary glycols have been prepared by the Grignard\u27s method from the Et esters of y-keto carboxylic acids
Bulk Negative Index Photonic Metamaterials for Direct Laser Writing
We show the designs of one- and two-dimensional photonic negative index
metamaterials around telecom wavelengths. Designed bulk structures are
inherently connected, which render their fabrication feasible by direct laser
writing and chemical vapor deposition.Comment: 12 pages, 4 figures, submitted to Opt. Let
Enhanced fano resonance of organic material films deposited on arrays of asymmetric split-ring resonators (A-SRRs)
Depositing very thin organic films on the surface of arrays of asymmetric split-ring resonators (A-SRRs) produces a shift in their resonance spectra that can be utilized for sensitive analyte detection. Here we show that when poly-methyl-methacrylate (PMMA) is used as an organic probe (analyte) on top of the A-SRR array, the phase and amplitude of a characteristic molecular Fano resonance associated with a carbonyl bond changes according to the spectral positions of the trapped mode resonance of the A-SRRs and their plasmonic reflection peaks. Furthermore, we localize blocks of PMMA at different locations on the A-SRR array to determine the effectiveness of detection of very small amounts of non-uniformly distributed analyte
Symmetries of Electrostatic Interaction between DNA Molecules
We study a model for pair interaction of DNA molecules generated by the
discrete dipole moments of base-pairs and the charges of phosphate groups, and
find noncommutative group of eighth order of symmetries that leave
invariant. We classify the minima using group and employ
numerical methods for finding them. The minima may correspond to several
cholesteric phases, as well as phases formed by cross-like conformations of
molecules at an angle close to , "snowflake phase". The results
depend on the effective charge of the phosphate group which can be modified
by the polycations or the ions of metals. The snowflake phase could exist for
above the threshold . Below there could be several cholesteric
phases. Close to the snowflake phase could change into the cholesteric
one at constant distance between adjacent molecules.Comment: 13 pages, 4 figure
Surface Scaling Analysis of a Frustrated Spring-network Model for Surfactant-templated Hydrogels
We propose and study a simplified model for the surface and bulk structures
of crosslinked polymer gels, into which voids are introduced through templating
by surfactant micelles. Such systems were recently studied by Atomic Force
Microscopy [M. Chakrapani et al., e-print cond-mat/0112255]. The gel is
represented by a frustrated, triangular network of nodes connected by springs
of random equilibrium lengths. The nodes represent crosslinkers, and the
springs correspond to polymer chains. The boundaries are fixed at the bottom,
free at the top, and periodic in the lateral direction. Voids are introduced by
deleting a proportion of the nodes and their associated springs. The model is
numerically relaxed to a representative local energy minimum, resulting in an
inhomogeneous, ``clumpy'' bulk structure. The free top surface is defined at
evenly spaced points in the lateral (x) direction by the height of the topmost
spring, measured from the bottom layer, h(x). Its scaling properties are
studied by calculating the root-mean-square surface width and the generalized
increment correlation functions C_q(x)= . The surface is
found to have a nontrivial scaling behavior on small length scales, with a
crossover to scale-independent behavior on large scales. As the vacancy
concentration approaches the site-percolation limit, both the crossover length
and the saturation value of the surface width diverge in a manner that appears
to be proportional to the bulk connectivity length. This suggests that a
percolation transition in the bulk also drives a similar divergence observed in
surfactant templated polyacrylamide gels at high surfactant concentrations.Comment: 17 pages RevTex4, 10 imbedded eps figures. Expanded discussion of
multi-affinit
Pedunculopontine nucleus gamma band activity-preconscious awareness, waking, and REM sleep
The pedunculopontine nucleus (PPN) is a major component of the reticular activating system (RAS) that regulates waking and REM sleep, states of high-frequency EEG activity. Recently,we described the presence of high threshold, voltage-dependent N- and P/Q-type calcium channels in RAS nuclei that subserve gamma band oscillations in the mesopontine PPN, intralaminar parafascicular nucleus (Pf), and pontine subcoeruleus nucleus dorsalis (SubCD). Cortical gamma band activity participates in sensory perception, problem solving, and memory. Rather than participating in the temporal binding of sensory events as in the cortex, gamma band activity in the RAS may participate in the processes of preconscious awareness, and provide the essential stream of information for the formulation of many of our actions.That is, the RAS may play an early permissive role in volition. Our latest results suggest that (1) the manifestation of gamma band activity during waking may employ a separate intracellular pathway compared to that during REM sleep, (2) neuronal calcium sensor (NCS-1) protein, which is over expressed in schizophrenia and bipolar disorder, modulates gamma band oscillations in the PPN in a concentration-dependent manner, (3) leptin, which undergoes resistance in obesity resulting in sleep dysregulation, decreases sodium currents in PPN neurons, accounting for its normal attenuation of waking, and (4) following our discovery of electrical coupling in the RAS, we Hypothesize that there are cell clusters within the PPN that may act in concert. These results provide novel information on the mechanisms controlling high-frequency activity related to waking and REM sleep by elements of the RAS.Fil: Urbano Suarez, Francisco Jose. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de FisiologĂa, BiologĂa Molecular y Neurociencias; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Investigaciones FarmacolĂłgicas (i); ArgentinaFil: Donofrio, Stasia M.. University Of Arkansas For Medical Sciences; Estados UnidosFil: Luster, Brennon R.. University Of Arkansas For Medical Sciences; Estados UnidosFil: Beck, Paige B.. University Of Arkansas For Medical Sciences; Estados UnidosFil: Hyde, James Robert. University Of Arkansas For Medical Sciences; Estados UnidosFil: Bisagno, Veronica. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Investigaciones FarmacolĂłgicas (i); Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de FisiologĂa, BiologĂa Molecular y Neurociencias; ArgentinaFil: Garcia Rill, Edgar. University Of Arkansas For Medical Sciences; Estados Unido
Defects in Chiral Columnar Phases: Tilt Grain Boundaries and Iterated Moire Maps
Biomolecules are often very long with a definite chirality. DNA, xanthan and
poly-gamma-benzyl-glutamate (PBLG) can all form columnar crystalline phases.
The chirality, however, competes with the tendency for crystalline order. For
chiral polymers, there are two sorts of chirality: the first describes the
usual cholesteric-like twist of the local director around a pitch axis, while
the second favors the rotation of the local bond-orientational order and leads
to a braiding of the polymers along an average direction. In the former case
chirality can be manifested in a tilt grain boundary phase (TGB) analogous to
the Renn-Lubensky phase of smectic-A liquid crystals. In the latter case we are
led to a new "moire" state with twisted bond order. In the moire state polymers
are simultaneously entangled, crystalline, and aligned, on average, in a common
direction. In the moire state polymers are simultaneously entangled,
crystalline, and aligned, on average, in a common direction. In this case the
polymer trajectories in the plane perpendicular to their average direction are
described by iterated moire maps of remarkable complexity, reminiscent of
dynamical systems.Comment: plain TeX, (33 pages), 17 figures, some uufiled and included, the
remaining available at ftp://ftp.sns.ias.edu/pub/kamien/ or by request to
[email protected]
A randomized phase I study of the safety and immunogenicity of three ascending dose levels of a 3-antigen Staphylococcus aureus vaccine (SA3Ag) in healthy adults
Background: Staphylococcus aureus is a common cause of healthcare-acquired morbidity and mortalityand increased healthcare resource utilization. A prophylactic vaccine is being developed that may reducethis disease burden.Methods: Volunteers in good general health aged 50–85 (n = 312) and 18–24 (n = 96) years were random-ized to receive a single intramuscular dose of one of three dose levels of a non-adjuvanted, 3-antigen S.aureus vaccine (SA3Ag) or placebo. SA3Ag antigens included capsular polysaccharides 5 and 8 (CP5 andCP8), each conjugated to cross-reactive material 197 (CRM197), and recombinant clumping factor A (ClfA).Safety, tolerability, and immunogenicity were evaluated.Results: At day 29 post-vaccination, robust immune responses were observed in both age cohorts at allthree SA3Ag dose levels. In the primary analysis population, the 50- to 85-year age stratum, geometricmean-fold-rises in competitive Luminex® immunoassay antibody titers from baseline ranged from 29.2to 83.7 (CP5), 14.1 to 31.0 (CP8), and 37.1 to 42.9 (ClfA), all (P < 0.001) exceeding the pre-defined two-fold rise criteria. Similar rises in opsonophagocytic activity assay titers demonstrated functionality ofthe immune response. Most injection-site reactions were mild in severity and there were no substantial differences (SA3Ag vs. placebo) with regard to systemic or adverse events.Conclusions: In this study of healthy adults aged 50–85 and 18–24 years, SA3Ag elicited a rapid and robustimmune response and was well tolerated, with no notable safety concerns.Michael Nissen, Helen Marshall, Peter Richmond, Sepehr Shakib, Qin Jiang, David Cooper, Denise Rill, James Baber, Joseph Eiden, William Gruber, Kathrin U. Jansen, Emilio A. Emini, Annaliesa S. Anderson, Edward T. Zito, Douglas Girgent
- …