2,296 research outputs found
The Outburst of the Blazar AO 0235+164 in 2006 December: Shock-in-Jet Interpretation
We present the results of polarimetric ( band) and multicolor photometric
() observations of the blazar AO 0235+16 during an outburst in 2006
December. The data reveal a short timescale of variability (several hours),
which increases from optical to near-IR wavelengths; even shorter variations
are detected in polarization. The flux density correlates with the degree of
polarization, and at maximum degree of polarization the electric vector tends
to align with the parsec-scale jet direction. We find that a variable component
with a steady power-law spectral energy distribution and very high optical
polarization (30-50%) is responsible for the variability. We interpret these
properties of the blazar withina model of a transverse shock propagating down
the jet. In this case a small change in the viewing angle of the jet, by
, and a decrease in the shocked plasma compression by a factor of
1.5 are sufficient to account for the variability.Comment: 22 pages, 8 figures, accepted for Ap
Fusion of neurohypophyseal membranes in vitro
Freeze cleaving electron microscopy has shown that fusion of isolated secretory vesicles from bovine neurohypophyses was induced by Ca
2+ in micromolar concentrations. Mg
2+ and Sr
2+ were ineffective. Mg
2+ inhibited Ca
2+-induced fusion.
In suspensions containing secretory vesicles as well as sheets of cell membrane, release of vasopressin parallel to intervesicular fusion of secretory vesicles with sheets of cell membrane was observed after exposure to Ca
2+. Mg
2+ and Sr
2+ were ineffective in replacing Ca
2+ as trigger for fusion or vasopressin release.
Intervesicular fusion and exocytotic profiles were observed when isolated neurohypophyses or neurosecretosome were exposed to cold
Spontaneous Symmetry Breaking at Infinite Momentum without P+ Zero-Modes
The nonrelativistic interpretation of quantum field theory achieved by
quantization in an infinite momentum frame is spoiled by the inclusion of a
mode of the field carrying p+=0. We therefore explore the viability of doing
without such a mode in the context of spontaneous symmetry breaking (SSB),
where its presence would seem to be most needed. We show that the physics of
SSB in scalar quantum field theory in 1+1 space-time dimensions is accurately
described without a zero-mode.Comment: LaTeX, 8 pages, 3 eps figure
Relationship between post-awakening salivary cortisol and melatonin secretion in healthy participants
We report the relationship between patterns of post-awakening salivary melatonin and cortisol secretion in healthy participants (n=51; mean age 21.6 Âą5.0 years). Saliva samples were collected within the domestic setting, at 0-, 15-, 30-, and 45-min post-awakening on 2 consecutive typical weekdays. Analyses were undertaken on data with electronically verified sample timing accuracy (55-min delay between awakening and the start of saliva sampling). Melatonin secretion declined linearly by an average of 29% within the first 45-min post-awakening. In contrast, there was a marked 112% surge in cortisol, characteristic of the cortisol awakening response. No day differences in melatonin or cortisol secretion were observed but melatonin concentrations were lower with later awakening. Despite contrasting post-awakening changes in these hormones, there was a lack of relationship between overall levels or patterns of melatonin and cortisol during this period
Detailed time course of the cortisol awakening response in healthy participants
The cortisol awakening response (CAR) can be assessed from saliva samples collected at home, which
confers ecological validity but lacks researcher oversight. Participant non-adherence to requested saliva
sampling regimes leads to inaccurate CAR estimates. Moderate sampling delays of just 8 (5â15) min
between awakening and commencement of saliva sampling are reported to result in over-estimated
CAR magnitude and earlier peaking. This has been attributed to an observed âlatentâ period in which
cortisol secretion does not increase for up to 10-min after awakening. Replication of this finding
is essential as the findings have considerable implications for CAR research. Healthy participants
(n = 26) collected saliva samples at 5-min intervals for 60 min on 2 consecutive typical weekdays.
Full electronic monitoring of awakening and sampling enabled exclusion of non-adherent data (i.e.,
delays of greater than 5 min between awakening and collection of the first sample). In the 0â15 min
post awakening segment of the CAR a quadratic effect was observed, with no difference between
the awakening and 5 and 10 min samples. Moderate sampling delays will shift assessment of the
CAR just sufficiently along the time axis to not impact upon measurement of the first sample but
to remove the immediate post-awakening latent period from CAR estimatesâwhilst retaining later
estimates of elevated cortisol secretion. The implication from these results is that accurate CAR
measures can only be determined from data with strict adherence to commencement of saliva sampling
following awakening
Increased Wellbeing following Engagement in a Group Nature-Based Programme: The Green Gym Programme Delivered by the Conservation Volunteers
The wellbeing benefits of engaging in a nature-based programme, delivered by the Voluntary, Community and Social Enterprise sector, were examined in this study. Prior to attending The Conservation Volunteersâ Green Gymâ˘, attendees (n = 892) completed demographics, health characteristics and the Warwick Edinburgh Mental Wellbeing Short-Form Scale. Attendees (n = 253, 28.4%) provided a measure on average 4.5 months later. There were significant increases in wellbeing after engaging in Green Gym, with the greatest increases in those who had the lowest starting levels of wellbeing. Wellbeing increases were sustained on average 8.5 months and 13 months later in those providing a follow up measure (n = 92, n = 40, respectively). Attendees who continued to engage in Green Gym but not provide follow up data (n = 318, 35.7%) tended to be more deprived, female and self-report a health condition. Attendees who did not continue to engage in Green Gym (n = 321, 36.0%) tended to be less deprived and younger. These findings provide evidence of the wellbeing benefits of community nature-based activities and social (âgreenâ) prescribing initiatives and indicate that Green Gym targets some groups most in need
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