3,221 research outputs found
AN EVALUATION OF ETHNICITY AND LINGUISTIC BACKGROUNDS AS WIC FOOD SELECTION DETERMINANTS
The federally funded Women, Infants, and Children (WIC) program issues redeemable food instruments (or vouchers) to low-income mothers and their small children who demonstrate nutritional need. Not all such food instruments are actually redeemed. Both ethnicity and home language preferences were found to be significantly correlated with individualsÂ’' WIC food instrument redemption likelihood. However, these correlations provided little indication that any food type (except cheese for Asians) is more or less culturally acceptable to any particular ethnic or language group. Regardless of ethnicity, persons who show English as their family language preference tend to have lower food instrument redemption rates than do those who prefer to speak any other language, at least among family members. This redemption rate disparity indicates that, to induce participants to follow dietary guidelines consistent with general public health goals, even a food assistance program, such as WIC, needs to employ some marketing techniques. Use of the English language should be a major consideration in segmenting WIC markets.Food Security and Poverty,
AN ILLUSTRATION OF THE NEED FOR AN INTERNATIONAL MARKETING PROFILE DATABASE: THE CASE OF EXPORTED U.S. APPLES
International Relations/Trade, Marketing,
Cosmic ray acceleration to ultrahigh energy in radio galaxies
The origin of ultrahigh energy cosmic rays (UHECRs) is an open question. In
this proceeding, we first review the general physical requirements that a
source must meet for acceleration to 10-100 EeV, including the consideration
that the shock is not highly relativistic. We show that shocks in the backflows
of radio galaxies can meet these requirements. We discuss a model in which
giant-lobed radio galaxies such as Centaurus A and Fornax A act as
slowly-leaking UHECR reservoirs, with the UHECRs being accelerated during a
more powerful past episode. We also show that Centaurus A, Fornax A and other
radio galaxies may explain the observed anisotropies in data from the Pierre
Auger Observatory, before examining some of the difficulties in associating
UHECR anisotropies with astrophysical sources.Comment: 6 pages, 4 figures. Proceedings of UHECR 2018, 8-12 October 2018,
Paris, Franc
Amplification of perpendicular and parallel magnetic fields by cosmic ray currents
Cosmic ray (CR) currents through magnetised plasma drive strong instabilities
producing amplification of the magnetic field. This amplification helps explain
the CR energy spectrum as well as observations of supernova remnants and radio
galaxy hot spots. Using magnetohydrodynamic (MHD) simulations, we study the
behaviour of the non-resonant hybrid (NRH) instability (also known as the Bell
instability) in the case of CR currents perpendicular and parallel to the
initial magnetic field. We demonstrate that extending simulations of the
perpendicular case to 3D reveals a different character to the turbulence from
that observed in 2D. Despite these differences, in 3D the perpendicular NRH
instability still grows exponentially far into the non-linear regime with a
similar growth rate to both the 2D perpendicular and 3D parallel situations. We
introduce some simple analytical models to elucidate the physical behaviour,
using them to demonstrate that the transition to the non-linear regime is
governed by the growth of thermal pressure inside dense filaments at the edges
of the expanding loops. We discuss our results in the context of supernova
remnants and jets in radio galaxies. Our work shows that the NRH instability
can amplify magnetic fields to many times their initial value in parallel and
perpendicular shocks.Comment: Published in MNRAS. 14 pages, 12 figures, 2 tables. Replacement
corrects some typesetting error
Infinite graphs and bicircular matroids
B-matroids are a class of pre-independence spaces which retain many important properties of independence spaces. Higgs has shown that an infinite generalization of the cycle matroid of a finite graph which admits two-way infinite paths as circuits need not be a B-matroid. In this note it is shown that a similar generalization of the finite bicircular matroid is a ways a B-matroid. © 1977
Structural Analysis by Enhanced Raman Scattering
Biological membrane structure is inherently complex, and understanding the structure of peptide chains inserted in membranes is vitally important for the development of effective diagnosis and treatments of diseases. Surface Enhanced Raman Spectroscopy (SERS) was used as a tool for studying lipid membrane structure in a natural fluid, room temperature environment.
Gold nanostructures focus light to a molecular length scale at their surface, creating the possibility to visualize molecular structure. Optical excitation of gold nanoparticles at their size and shape-dependent plasmon resonant frequency induces strong oscillations of the nanoparticle’s free electron gas, leading to SERS – an enhancement of Raman scattering signals in a distance dependent manner at the molecular scale. This project utilizes gold nanorods, tuned to an excitation laser wavelength of 785 nm, as a substrate for lipid membranes so that their structure can be analyzed by SERS.
The surfactant cetyltrimethylammonium bromide (CTAB) that stabilizes nanorods was exchanged with the biologically relevant lipid dioleoylphosphatidylcholine (DOPC), and the insertion of the peptide residue tryptophan into the lipid membrane was observed using SERS for confirmation. Full
characterization of the lipid membranes was carried out, demonstrating a well ordered, gold supported bilayer.
SERS spectra also contain information on molecular position and orientation relative to the surface, but are difficult to interpret quantitatively. An analysis method that combines SERS and unenhanced Raman spectra with theoretical calculations of the optical field and molecular polarizability is introduced. Together these reveal the molecular orientation and position of surfactant layers on gold nanorods and of tryptophan in phospholipid bilayers. This method offers a new approach to analyzing lipid membrane molecular structure under ambient conditions, with microscopic quantities, and without molecular labels
Efficient adenovirus-mediated gene transfer into primary T cells and thymocytes in a new coxsackie/adenovirus receptor transgenic model
BACKGROUND: Gene transfer studies in primary T cells have suffered from the limitations of conventional viral transduction or transfection techniques. Replication-defective adenoviral vectors are an attractive alternative for gene delivery. However, naive lymphocytes are not readily susceptible to infection with adenoviruses due to insufficient expression of the coxsackie/adenovirus receptor. RESULTS: To render T cells susceptible to adenoviral gene transfer, we have developed three new murine transgenic lines in which expression of the human coxsackie/adenovirus receptor (hCAR) with a truncated cytoplasmic domain (hCARΔcyt) is limited to thymocytes and lymphocytes under direction of a human CD2 mini-gene. hCARΔcyt.CD2 transgenic mice were crossed with DO11.10 T cell receptor transgenic mice (DO11.hCARΔcyt) to allow developmental studies in a defined, clonal T cell population. Expression of hCARΔcyt enabled adenoviral transduction of resting primary CD4(+) T cells, differentiated effector T cells and thymocytes from DO11.hCARΔcyt with high efficiency. Expression of hCARΔcyt transgene did not perturb T cell development in these mice and adenoviral transduction of DO11.hCARΔcyt T cells did not alter their activation status, functional responses or differentiative potential. Adoptive transfer of the transduced T cells into normal recipients did not modify their physiologic localization. CONCLUSION: The DO11.hCARΔcyt transgenic model thus allows efficient gene transfer in primary T cell populations and will be valuable for novel studies of T cell activation and differentiation
The long-period variable stars of M33
Infrared photometry of long-period variables (LPVs) in M33 shows that the majority of those identified up to now are supergiants. The period-luminosity relation for these stars yields a distance of M33 of 760 kpc with a 10 percent uncertainty. This uncertainty primarily reflects the uncertain distance of the Large Magellanic Cloud, although the broader P - L relation of M33 is a contributing factor. Cepheid period-luminosity relations yield a distance at the low end of this range; RR Lyrae stars tend toward the high end. The remaining LPVs are asymptotic giant branch stars. There is one confirmed carbon star among them
Recent Decisions
Comments on recent decisions by William J. Daner, William T. Huston, James D. Matthews, Benedict R. Danko, John E. Lindberg, Maynard R. Bissonnette, Joseph H. Harrison, Peter J. Donahue, Louis J. Mustico, Donald John Tufts, Henry M. Shine, Jr., Arthur L. Beaudette, Luke R. Morin, John F. Mendoza, and Thomas A. Muscatello
The Signature of Primordial Grain Growth in the Polarized Light of the AU Mic Debris Disk
We have used the Hubble Space Telescope/ACS coronagraph to make polarization
maps of the AU Mic debris disk. The fractional linear polarization rises
monotonically from about 0.05 to 0.4 between 20 and 80 AU. The polarization is
perpendicular to the disk, indicating that the scattered light originates from
micron sized grains in an optically thin disk. Disk models, which
simultaneously fit the surface brightness and polarization, show that the inner
disk (< 40-50 AU) is depleted of micron-sized dust by a factor of more than
300, which means that the disk is collision dominated. The grains have high
maximum linear polarization and strong forward scattering. Spherical grains
composed of conventional materials cannot reproduce these optical properties. A
Mie/Maxwell-Garnett analysis implicates highly porous (91-94%) particles. In
the inner Solar System, porous particles form in cometary dust, where the
sublimation of ices leaves a "bird's nest" of refractory organic and silicate
material. In AU Mic, the grain porosity may be primordial, because the dust
"birth ring" lies beyond the ice sublimation point. The observed porosities
span the range of values implied by laboratory studies of particle coagulation
by ballistic cluster-cluster aggregation. To avoid compactification, the upper
size limit for the parent bodies is in the decimeter range, in agreement with
theoretical predictions based on collisional lifetime arguments. Consequently,
AU Mic may exhibit the signature of the primordial agglomeration process
whereby interstellar grains first assembled to form macroscopic objects.Comment: 12 pages, 8 figures, ApJ, in pres
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