1,660 research outputs found
Immunology of the canine eye in health and disease: A concise review
The canine eye is an immune-privileged organ that is provided with systems to prevent and control
the local immune response, which could have a detrimental impact. The entry of blood-derived antigens is hindered
by the blood-ocular barriers and potential invading pathogens are tackled by local antimicrobial molecules.
Despite the existence of numerous immune-competent cells, the anterior chamber of the eye is characterised by
low responsiveness. This review is focused on the innate and adaptive immunity employed to control health and
disease in the canine eye
The evolution of individual and cultural variation in social learning
AcceptedReviewIt is often assumed in experiments and models that social learning abilities – how often individuals copy others, plus who and how they copy – are species-typical. Yet there is accruing evidence for systematic individual variation in social learning within species. Here we review evidence for this individual variation, placing it within a continuum of increasing phenotypic plasticity, from genetically polymorphic personality traits, to developmental plasticity via cues such as maternal stress, to the individual learning of social learning, and finally the social learning of social learning. The latter, possibly restricted to humans, can generate stable between-group cultural variation in social learning. More research is needed to understand the extent, causes, and consequences of this individual and cultural variation.Economic and Social Research Council (UK)Research Grants Council (Hong Kong)Leverhulme Trust International NetworkBBSRC David Phillips Fellowshi
Paired atom laser beams created via four-wave mixing
A method to create paired atom laser beams from a metastable helium atom
laser via four-wave mixing is demonstrated. Radio frequency outcoupling is used
to extract atoms from a Bose Einstein condensate near the center of the
condensate and initiate scattering between trapped and untrapped atoms. The
unequal strengths of the interactions for different internal states allows an
energy-momentum resonance which leads to the creation of pairs of atoms
scattered from the zero-velocity condensate. The resulting scattered beams are
well separated from the main atom laser in the 2-dimensional transverse atom
laser profile. Numerical simulations of the system are in good agreement with
the observed atom laser spatial profiles, and indicate that the scattered beams
are generated by a four-wave mixing process, suggesting that the beams are
correlated.Comment: 5 pages, 3 figure
The amplitude of solar oscillations using stellar techniques
The amplitudes of solar-like oscillations depend on the excitation and
damping, both of which are controlled by convection. Comparing observations
with theory should therefore improve our understanding of the underlying
physics. However, theoretical models invariably compute oscillation amplitudes
relative to the Sun, and it is therefore vital to have a good calibration of
the solar amplitude using stellar techniques. We have used daytime spectra of
the Sun, obtained with HARPS and UCLES, to measure the solar oscillations and
made a detailed comparison with observations using the BiSON helioseismology
instrument. We find that the mean solar amplitude measured using stellar
techniques, averaged over one full solar cycle, is 18.7 +/- 0.7 cm/s for the
strongest radial modes (l=0) and 25.2 +/- 0.9 cm/s for l=1. In addition, we use
simulations to establish an equation that estimates the uncertainty of
amplitude measurements that are made of other stars, given that the mode
lifetime is known. Finally, we also give amplitudes of solar-like oscillations
for three stars that we measured from a series of short observations with HARPS
(gamma Ser, beta Aql and alpha For), together with revised amplitudes for five
other stars for which we have previously published results (alpha Cen A, alpha
Cen B, beta Hyi, nu Ind and delta Pav).Comment: 8 pages, accepted by ApJ. Minor wording changes and added a referenc
Attitudes to ageing and objectively-measured sedentary and walking behaviour in older people: the Lothian Birth Cohort 1936
Background:Prolonged sitting and low activity—both common in older people—are associated with increased mortality and poorer health. Whether having a more negative attitude to ageing is associated with higher levels of these behaviours is unclear.Objective:We investigated the prospective relationship between attitudes to ageing and objectively measured sedentary and walking behaviour.Methods:Participants were 271 members of the Lothian Birth Cohort 1936. At age 72 years, participants completed the Attitudes to Ageing Questionnaire which assesses attitudes on three domains—Psychosocial loss, Physical change and Psychological growth. At age 79 years, participants wore an activPAL activity monitor for seven days. The outcome measures were average daily time spent sedentary, number of sit-to-stand transitions, and step count.Results:There were no significant associations between any of the Attitude to Ageing domain scores and time spent sedentary or number of sit-to-stand transitions. In sex-adjusted analysis, having a more positive attitude to ageing as regards Physical change was associated with a slightly higher daily step count, for a SD increment in score, average daily step count was greater by 1.5% (95% CI 0.6%, 2.4%). On further adjustment for potential confounding factors these associations were no longer significant.Conclusion:We found no evidence that attitudes to ageing at age 72 were predictive of sedentary or walking behaviour seven years later. Future studies should examine whether attitudes to ageing are associated with objectively measured walking or sedentary behaviour at the same point in time. The existence of such an association could inform the development of interventions.<br/
Intermittency of glassy relaxation and the emergence of a non-equilibrium spontaneous measure in the aging regime
We consider heat exchange processes between non-equilibrium aging systems (in
their activated regime) and the thermal bath in contact. We discuss a scenario
where two different heat exchange processes concur in the overall heat
dissipation: a stimulated fast process determined by the temperature of the
bath and a spontaneous intermittent process determined by the fact that the
system has been prepared in a non-equilibrium state. The latter is described by
a probability distribution function (PDF) that has an exponential tail of width
given by a parameter , and satisfies a fluctuation theorem (FT)
governed by that parameter. The value of is proportional to the
so-called effective temperature, thereby providing a practical way to
experimentally measure it by analyzing the PDF of intermittent events.Comment: Latex file, 8 pages + 5 postscript figure
Prøver med Ajlespredere paa „Lykkensgave“ ved Taastrup Station.
Prøver med Ajlespredere paa „Lykkensgave“ ved Taastrup Station
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