313 research outputs found
Cold streams of ionospheric oxygen in the plasma sheet during the CDAW-6 event of March 22, 1979
During magnetospheric substorm events, the plasma and ion composition experiments in the ISEE-1 and 2 satellites detected cold ionospheric O+ streams, moving tailwards in the near Earth magnetotail. Flow is parallel to the magnetic field lines, with drift velocity in agreement with the electric field topology obtained by mapping the model ionospheric field along the magnetic field lines. Fluctuations of the flow velocity of the streams can be related to magnetotail movements. Oscillations of the flow direction and speed with periods ranging from 5 to 10 min that suggest the presence of waves are observed. The streams are observed at all distances between 15 and 6 Re from the Earth. When averaged over 360 deg, the streams show up as a low energy peak, superimposed on the distribution of isotropic plasma sheet ions. This double-peak structure of the energy spectrum seems typical of the disturbed plasma sheet
Simultaneous all-optical add and drop multiplexing of 40-Gbit/s OTDM signals using monolithically integrated Mach-Zehnder interferometer
A bit-rate flexible and power efficient all-optical demultiplexer realised by monolithically integrated Michelson interferometer
Deep phenotyping of the unselected COPSAC2010 birth cohort study
BACKGROUND: We hypothesize that perinatal exposures, in particular the human microbiome and maternal nutrition during pregnancy, interact with the genetic predisposition to cause an abnormal immune modulation in early life towards a trajectory to chronic inflammatory diseases such as asthma and others. OBJECTIVE: The aim of this study is to explore these interactions by conducting a longitudinal study in an unselected cohort of pregnant women and their offspring with emphasis on deep clinical phenotyping, exposure assessment, and biobanking. Exposure assessments focus on the human microbiome. Nutritional intervention during pregnancy in randomized controlled trials are included in the study to prevent disease and to be able to establish causal relationships. METHODS: Pregnant women from eastern Denmark were invited during 2008–2010 to a novel unselected ‘COPSAC(2010)’ cohort. The women visited the clinic during pregnancy weeks 24 and 36. Their children were followed at the clinic with deep phenotyping and collection of biological samples at nine regular visits until the age of 3 and at acute symptoms. Randomized controlled trials of high‐dose vitamin D and fish oil supplements were conducted during pregnancy, and a trial of azithromycin for acute lung symptoms was conducted in the children with recurrent wheeze. RESULTS: Seven hundred and thirty‐eight mothers were recruited from week 24 of gestation, and 700 of their children were included in the birth cohort. The cohort has an over‐representation of atopic parents. The participant satisfaction was high and the adherence equally high with 685 children (98%) attending the 1 year clinic visit and 667 children (95%) attending the 2 year clinic visit. CONCLUSIONS: The COPSAC(2010) birth cohort study provides longitudinal clinical follow‐up with highly specific end‐points, exposure assessments, and biobanking. The cohort has a high adherence rate promising strong data to elucidate the interaction between genomics and the exposome in perinatal life leading to lifestyle‐related chronic inflammatory disorders such as asthma
Deconstructing essentialisms: An ethnographic exploration of Chinese Canadians in Kitchener-Waterloo
As an alternate conceptualization to the commonly used category of a Chinese community, ideal types of a front and back stage of Chinese identification are constructed dialectically. These ideal types show that while there is a commonly shared understanding around the term 'Chinese' (the front stage), it is simplistic and falsely homogeneous. It is the shared aspect of the front stage of Chinese identity, by both non-Chinese and Chinese people, that gives the front stage meaning--it is not a culture or community. The back stage is where a myriad of distinctions and categories hold meaning for Chinese Canadians, and this arena of self and other identification is all too often glossed over by researchers reifying Chinese communities. There is, however, more meaning to Chinese identity than is evidenced by the front stage. A further set of ideal types are constructed to demonstrate this, based on a dominant discourse in Canada that blurs community, ethnicity and culture into reified essences based on heritage; and, a demotic discourse that is bounded by the dominant one. (Abstract shortened by UMI.
Disc dichotomy signature in the vertical distribution of [Mg/Fe] and the delayed gas infall scenario
The analysis of the APOGEE data suggests the existence of a clear distinction
between two sequences of disc stars in the [/Fe] vs. [Fe/H] abundance
ratio space. We aim to test if the two-infall chemical evolution models
designed to reproduce these two sequences in the solar neighbourhood are also
capable to predict the disc bimodality observed in the vertical distribution of
[Mg/Fe] in APOGEE DR16 data. Along with the predicted chemical composition of
SSPs born at different Galactic times in the solar vicinity, we provide their
maximum vertical height |zmax| above the Galactic plane computed assuming the
relation between the vertical action and stellar age in thin disc stars. The
predicted vertical distribution of the [Mg/Fe] abundance ratio is in agreement
with the one observed combining the APOGEE DR16 data and the astroNN catalogue
(stellar ages, orbital parameters) for stars younger than 8 Gyr (only
low- sequence stars). Including the high- disc component, the
dichotomy in the vertical [Mg/Fe] abundance distribution is reproduced
considering the observational cut in the Galactic height of |z| < 2 kpc.
However, our model predicts a too flat growth of the |zmax| as a function of
[Mg/Fe] for high- objects in contrast with the median values from
APOGEE data. Possible explanations for such a tension are: i) the data sample
with |z| < 2 kpc is more likely contaminated by halo stars, causing the median
values to be kinematically hotter, ii) external perturbations such as minor
mergers could have heated up the disc, and the heating of the orbits cannot be
modelled by only scattering processes. Assuming for the data a disc dissection
based on chemistry, the observed |zmax| distributions for high- and
low- sequences are in good agreement with our model predictions if we
consider in the calculation the errors in the vertical action estimates.Comment: Accepted for publication in Astronomy and Astrophysics (A&A), 17
pages, 15 figure
Childbirth and consequent atopic disease: emerging evidence on epigenetic effects based on the hygiene and EPIIC hypotheses
Background: In most high and middle income countries across the world, at least 1:4 women give birth by cesarean
section. Rates of labour induction and augmentation are rising steeply; and in some countries up to 50 % of laboring
women and newborns are given antibiotics. Governments and international agencies are increasingly concerned about
the clinical, economic and psychosocial effects of these interventions.
Discussion: There is emerging evidence that certain intrapartum and early neonatal interventions might affect the
neonatal immune response in the longer term, and perhaps trans-generationally. Two theories lead the debate in this
area. Those aligned with the hygiene (or ‘Old Friends’) hypothesis have examined the effect of gut microbiome colonization
secondary to mode of birth and intrapartum/neonatal pharmacological interventions on immune response and epigenetic
phenomena. Those working with the EPIIC (Epigenetic Impact of Childbirth) hypothesis are concerned with the effects of
eustress and dys-stress on the epigenome, secondary to mode of birth and labour interventions.
Summary: This paper examines the current and emerging findings relating to childbirth and atopic/autoimmune
disease from the perspective of both theories, and proposes an alliance of research effort. This is likely to accelerate
the discovery of important findings arising from both approaches, and to maximize the timely understanding of the
longer-term consequences of childbirth practices
Red Horizontal Branch stars: an asteroseismic perspective
Robust age estimates of red giant stars are now possible thanks to the
precise inference of their mass based on asteroseismic constraints. However,
there are cases where such age estimates can be highly precise yet very
inaccurate. An example is giants that have undergone mass loss or mass transfer
events that have significantly altered their mass. In this context, stars with
"apparent" ages significantly higher than the age of the Universe are
candidates as stripped stars, or stars that have lost more mass than expected,
most likely via interaction with a companion star, or because of the poorly
understood mass-loss mechanism along the red-giant branch. In this work we
identify examples of such objects among red giants observed by
, both at low ([Fe/H] ) and solar metallicity.
By modelling their structure and pulsation spectra, we find a consistent
picture confirming that these are indeed low-mass objects consisting of a He
core of and an envelope of . Moreover, we find that these stars are characterised by a rather
extreme coupling () between the pressure-mode and gravity-mode
cavities, i.e. much higher than the typical value for red clump stars,
providing thus a direct seismic signature of their peculiar structure. The
complex pulsation spectra of these objects, if observed with sufficient
frequency resolution, hold detailed information about the structural properties
of likely products of mass stripping, hence can potentially shed light on their
formation mechanism. On the other hand, our tests highlight the difficulties
associated with measuring reliably the large frequency separation, especially
in shorter datasets, with impact on the reliability of the inferred masses and
ages of low-mass Red Clump stars with e.g. K2 or TESS data.Comment: Accepted for publication in A&A Letter
An asteroseismic age estimate of the open cluster NGC 6866 using Kepler and Gaia
Asteroseismology of solar-like oscillations in giant stars allow the
derivation of their masses and radii. For members of open clusters this allows
an age estimate of the cluster which should be identical to the age estimate
from the colour-magnitude diagram, but independent of the uncertainties that
are present for that type of analysis. Thus, a more precise and accurate age
estimate can be obtained. We aim to measure asteroseismic properties of
oscillating giant members of the open cluster NGC 6866 and utilise these for a
cluster age estimate. Model comparisons allow constraints on the stellar
physics, and here we investigate the efficiency of convective-core overshoot
and effects of rotation during the main-sequence, which has a significant
influence on the age for these relatively massive giants. We identify six giant
members of NGC 6866 and derive asteroseismic measurements for five of them.
This constrains the convective-core overshoot and enables a more precise and
accurate age estimate than previously possible. Asteroseismology establishes
the helium-core burning evolutionary phase for the giants, which have a mean
mass of 2.8 . Their radii are significantly smaller than predicted
by current 1D stellar models unless the amount of convective-core overshoot on
the main sequence is reduced to in the
step-overshoot description. Our measurements also suggest that rotation has
affected the evolution of the stars in NGC 6866 in a way that is consistent
with 3D simulations but not with current 1D stellar models. The cluster age is
estimated to be 0.43 0.05 Gyr, significantly younger and more precise
than most previous estimates. We derive a precise cluster age while
constraining convective-core overshooting and effects of rotation in the
models. We uncover potential biases for automated age estimates of helium-core
burning stars.Comment: Accepted on 21/08/2023 for publication in Section 7. Stellar
structure and evolution of Astronomy & Astrophysics. 20 Pages, 11 Figures +
appendi
Long-Term Opioid Therapy in Spine Center Outpatients:Protocol for the Spinal Pain Opioid Cohort (SPOC) Study
BACKGROUND: Spinal pain is the leading cause of patient-years lived with chronic pain and disability worldwide. Although opioids are well documented as an effective short-term pain-relieving medication, more than a few weeks of treatment may result in a diminishing clinical effect as well as the development of addictive behavior. Despite recognition of opioid addiction in pain patients as a major problem commonly experienced in the clinic, no reference material exists on the scope of long-term problems in novel opioid users and the link to clinical outcomes.OBJECTIVE: The main aims of this study are to describe baseline and follow-up characteristics of the Spinal Pain Opioid Cohort (SPOC), to evaluate the general use of opioids in spinal pain when an acute pain episode occurs, and to demonstrate the prevalence of long-term opioid therapy (LTOT).METHODS: Prospective clinical registry data were collected from an outpatient spine center setting during 2012-2013 including patients with a new spinal pain episode lasting for more than 2 months, aged between 18 and 65 years who had their first outpatient visit in the center. Variables include demographics, clinical data collected in SpineData, the Danish National Patient Register, and The Danish National Prescription Registry. The primary outcome parameter is long-term prescription opioid use registered from 4 years before the first spine center visit to 5 years after.RESULTS: This is an ongoing survey. It is estimated that more than 8000 patients fulfill the SPOC inclusion criteria. In 2019, we began the intellectual process of identifying the most relevant supplementary data available from the wide range of existing national registries available in Denmark. We have now begun merging SpineData with relevant opioid data from Danish national registers and will continue to extract data up to 2021-2022. We will also be looking at data regarding somatic or psychiatric hospitalization patterns, patient usage of health care resources, as well as their working status and disability pensions.CONCLUSIONS: To our knowledge, this survey will be the first to document the scope of long-term problems regarding LTOT and opioid addiction following new spinal pain episodes and comparing descriptive follow-up data between substance users and nonusers.TRIAL REGISTRATION: ISRCTN Registry ISRCTN69685117; http://www.isrctn.com/ISRCTN69685117.INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/21380.</p
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