1,859 research outputs found
First Results From the Large Binocular Telescope: Deep Photometry of New dSphs
This contribution describes photometry for two Galactic dSphs obtained with
the Large Binocular Telescope to a magnitude of ~25.5. Using the Large
Binocular Camera, a purpose-built wide-field imager for the LBT, we have
examined the structure and star formation histories of two newly-discovered
Local Group members, the Hercules dSph and the Leo T dSph/dIrr system. We have
constructed a structural map for the Hercules system using three-filter
photometry to V ~ 25.5. This is the first deep photometry for this system, and
it indicates that Hercules is unusually elongated, possibly indicating
distortion due to the Galactic tidal field. We have also derived the first star
formation history for the Leo T system, and find that its oldest population of
stars (age ~ 13 Gyr) were relatively metal-rich, with [Fe/H] ~ -1.5.Comment: Four pages, two figures. To appear in the proceedings of "Galaxies in
the Local Volume", Astrophysics and Space Science, editors B. Koribalski and
H. Jerje
Simultaneous Projectile-Target Excitation in Heavy Ion Collisions
We calculate the lowest-order contribution to the cross section for
simultaneous excitation of projectile and target nuclei in relativistic heavy
ion collisions. This process is, to leading order, non-classical and adds
incoherently to the well-studied semi-classical Weizs\"acker-Williams cross
section. While the leading contribution to the cross section is down by only
from the semiclassical process, and consequently of potential
importance for understanding data from light projectiles, we find that phase
space considerations render the cross section utterly negligible.Comment: 9 pages, LA-UR-94-247
A Quantum-Mechanical Equivalent-Photon Spectrum for Heavy-Ion Physics
In a previous paper, we calculated the fully quantum-mechanical cross section
for electromagnetic excitation during peripheral heavy-ion collisions. Here, we
examine the sensitivity of that cross section to the detailed structure of the
projectile and target nuclei. At the transition energies relevant to nuclear
physics, we find the cross section to be weakly dependent on the projectile
charge radius, and to be sensitive to only the leading momentum-transfer
dependence of the target transition form factors. We exploit these facts to
derive a quantum-mechanical ``equivalent-photon spectrum'' valid in the
long-wavelength limit. This improved spectrum includes the effects of
projectile size, the finite longitudinal momentum transfer required by
kinematics, and the response of the target nucleus to the off-shell photon.Comment: 19 pages, 5 figure
A novel dynamic exercise initiative for older people to improve health and well-being: Study protocol for a randomized controlled trial
Background: Exercise is an important and effective approach to preventing falls in older people, but adherence to exercise participation remains a persistent problem. A unique purpose-built exercise park was designed to provide a fun but physically challenging environment to support exercise in a community setting. This project is a randomised controlled trial designed to evaluate the effectiveness of an exercise intervention using an exercise park specifically designed for older people in reducing the risk of falls.
Methods/Design: This study will be a parallel randomised control trial with pre and post intervention design.
One hundred and twenty people aged between 60 and 90 years old will be recruited from Melbourne suburbs and will be randomly allocated to either an exercise park intervention group (EPIG) or a control group (CG). The CG will receive social activities and an educational booklet on falls prevention. The BOOMER balance test will be used as the primary outcome measure. Secondary outcome measures will include hand grip strength, two
minute walk test, lower limb strength test, spatio-temporal walking parameters, health related quality of life, feasibility, adherence, safety, and a number of other psychosocial measures. Outcome assessment will be conducted at baseline and at 18 and 26 weeks after intervention commencement. Participants will inform their falls and physical activity history for a 12-month period via monthly calendars. Mixed linear modelling incorporating intervention and control groups at the baseline and two follow up time points (18 weeks and 26 weeks after intervention commencement) will be used to assess outcomes.
Discussion: This planned trial will be the first to provide evidence if the exercise park can improve functional and physiological health, psychological and well-being. In addition, this study will provide empirical evidence for
effectiveness and explore the barriers to participation and the acceptability of the senior exercise park in the
Australian older community
Electromagnetic Dissociation of Nuclei in Heavy-Ion Collisions
Large discrepancies have been observed between measured Electromagnetic
Dissociation(ED) cross sections and the predictions of the semiclassical
Weiz\"acker-Williams-Fermi(WWF) method. In this paper, the validity of the
semiclassical approximation is examined. The total cross section for
electromagnetic excitation of a nuclear target by a spinless projectile is
calculated in first Born approximation, neglecting recoil. The final result is
expressed in terms of correlation functions and convoluted densities in
configuration space. The result agrees with the WWF approximation to leading
order(unretarded electric dipole approximation), but the method allows an
analytic evaluation of the cutoff, which is determined by the details of the
electric dipole transition charge density. Using the Goldhaber-Teller model of
that density, and uniform charge densities for both projectile and target, the
cutoff is determined for the total cross section in the nonrelativistic limit,
and found to be smaller than values currently used for ED calculations. In
addition, cross sections are calculated using a phenomenological momentum space
cutoff designed to model final state interactions. For moderate projectile
energies, the calculated ED cross section is found to be smaller than the
semiclassical result, in qualitative agreement with experiment.Comment: 28 page
Olfactory rod cells : a rare cell type in the larval zebrafish olfactory epithelium with an actin-rich apical projection
We report the presence of a rare cell type, the olfactory rod cell, in the developing zebrafish olfactory epithelium. These cells each bear a single actin-rich rod-like apical projection extending about 10 μm from the epithelial surface. Live imaging with a ubiquitous Lifeact-RFP label indicates that the rods can oscillate. Olfactory rods arise within a few hours of the olfactory pit opening, increase in numbers and size during larval stages, and can develop in the absence of olfactory cilia. Olfactory rod cells differ in morphology from the known classes of olfactory sensory neuron, but express reporters driven by neuronal promoters. The cells also differ from secondary sensory cells such as hair cells of the inner ear or lateral line, or sensory cells in the taste bud, as they are not associated with established synaptic terminals. A sub-population of olfactory rod cells expresses a Lifeact-mRFPruby transgene driven by the sox10 promoter. Mosaic expression of this transgene reveals that olfactory rod cells have rounded cell bodies located apically in the olfactory epithelium
An “off-the shelf” Synthetic Membrane to Simplify Regeneration of Damaged Corneas
yesOur overall aim is to develop a synthetic off-the-shelf alternative to human amniotic membrane which is currently used for delivering cultured limbal stem cells to the cornea in patients who suffer scarring of the cornea because of the loss of limbal stem cells. We have recently reported that both cultured cells and limbal explants grow well on electrospun Poly(D,L-lactide-co-glycolide) (PLGA) (44 kg/mol) with a 50:50 ratio of lactide and glycolide and sterilized with γ-irradiation. Prior to undertaking a clinical study our immediate aim now is to achieve long term storage of the membranes in convenient to use packaging. Membranes were electrospun from Poly(D,L-lactide-co-glycolide) (44 kg/mol) with a 50:50 ratio of lactide and glycolide and sterilized with γ-irradiation and then stored dry (with desiccant) for several months at -80°C and -20°C , Room temperature (UK and India), 37°C and 50°C. We explored the contribution of vacuum sealing and the use of a medical grade bag (PET/Foil/LDPE) to achieve a longer shelf life. Confirmation of membranes being suitable for clinical use was obtained by culturing tissue explants on membranes post storage. When scaffolds were stored dry the rate of breakdown was both temperature and time dependent. At -20°C and -80°C there was no change in fiber diameter over 18 months of storage, and membranes were stable for 12 months at 4°C while at 50°C (above the transition temperature for PLGA) scaffolds lost integrity after several weeks. The use of vacuum packaging and a medical grade bag both improved the storage shelf-life of the scaffolds. The impact of temperature on storage is summarized beneath. We report that this synthetic membrane can be used as an off-the-shelf or-out-of-the freezer alternative to the amniotic membrane for corneal regeneration
Renormalization group and isochronous oscillations
We show how the condition of isochronicity can be studied for two dimensional
systems in the renormalization group (RG) context. We find a necessary
condition for the isochronicity of the Cherkas and another class of cubic
systems. Our conditions are satisfied by all the cases studied recently by
Bardet et al \cite{bard} and Ghose Choudhury and Guh
Stress-induced modulation of endocannabinoid signaling leads to delayed strengthening of synaptic connectivity in the amygdala
none11siopenYasmin, F.; Colangeli, R.; Morena, M.; Filipski, S.; van der Stelt, M.; Pittman, Q.J.; Hillard, C.J.; Campbell Teskey, G.; McEwen, B.S.; Hill, M.N.; Chattarji, S.Yasmin, F.; Colangeli, R.; Morena, M.; Filipski, S.; van der Stelt, M.; Pittman, Q. J.; Hillard, C. J.; Campbell Teskey, G.; Mcewen, B. S.; Hill, M. N.; Chattarji, S
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