86 research outputs found
Dinoflagellate blooms and physical systems in the Gulf of Maine
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 1990Numerous studies have shown dinoflagellate blooms to be
closely related to density discontinuities and fronts in the ocean. The
spatial and temporal patterns of the dinoflagellate population
depend on the predominant mode of physical forcing, and its scales
of variability. The present study combined field sampling of
hydrographic and biological variables to examine the relationship of
dinoflagellate population distributions to physical factors along the
southwestern cost of the Gulf of Maine.
A bloom of Ceratium longipes occurred along this coast during
the month of June, 1987. A simple model which coupled along-isopycnal
diffusion with the logistic growth equation suggested that
the cells had a growth rate of about 0.1 d-1 , and had reached a
steady horizontal across-shelf distribution within about 10 d.
Fur~her variations in population density appeared to be related to
fluctuations of light with periods of -10 d. To our knowledge, this
was the first use of this simple diffusion model as a diagnostic tool
for quantifying parameters describing the growth and movement of
a specific phytoplankton population.
Blooms of the toxic dinoflagellate, Alexandrium tamarense
have been nearly annual features along the coasts of southern
Maine, New Hampshire and Massachusetts since 1972; however the
mechanisms controlling the distribution of cells and concomitant
shellfish toxicity are relatively poorly understood. Analysis of field
data gathered from April to September, 1987-1989, showed that in
two years when toxicity was detected in the southern part of this
region, A. tamarense cells were apparently transported into the
study area between Portsmouth and Cape Ann, Massachusetts, in a
coastally trapped buoyant plume. This plume appears to have been
formed off Maine by the outflow from the Androscoggin and Kennebec Rivers. Flow rates of these rivers, hydrographic sections,
and satellite images suggest that the plume had a duration of about
a month, and extended alongshore for several hundred kilometers.
The distribution of cells followed the position of the plume as it was
influenced by wind and topography. Thus when winds were
downwelling-favourable, cells were moved alongshore to the south,
and were held to the coast; when winds were upwelling-favourable,
the plume sometimes separated from the coast, advecting the cells
offshore.
The alongshore advection of toxic cells within a coastally
trapped buoyant plume can explain the temporal and spatial
patterns of shellfish toxicity along the coast. The general observation
of a north-to-south temporal trend of toxicity is consistent with the
southward advection of the plume. In 1987 when no plume was
present, Alexandrium tamarense cells were scarce, and no toxicity
was recorded at the southern stations. A hypothesis was formulated
explaining the development and spread of toxic dinoflagellate
blooms in this region. This plume-advection hypothesis included:
source A. tamarense populations in the north, possibly associated
with the Androscoggin and Kennebec estuaries; a relationship
between toxicity patterns and river flow volume and timing of flow
peaks; and a relationship between wind stresses and the distribution
of low salinity water and cells. Predictions of the plume-advection hypothesis were tested
with historical records of shellfish toxicity, wind speed and direction,
and river flow. The predictions tested included the north-south
progression of toxic outbreaks, the occurrence of a peak in river flow
prior to the PSP events, the relationship of transit time of PSP
toxicity along the coast with river flow volume, and the influence of
surface wind stress on the timing and location of shellfish toxicity.
All the predictions tested were supported by the historical records.
In addition it was found that the plume-advection hypothesis
explains many details of the timing and spread of shellfish toxicity,
including the sporadic nature of toxic outbreaks south of
Massachusetts Bay, and the apparently rare occurrence of toxicity
well offshore on Nantucket Shoals and Georges Bank.This research was supported by
ONR contract N00014-87-K-0007 and ONR grant N00014-89-J-111
to Donald M. Anderson, and NOAA Office of Sea Grant contract
NA86AA-D-SG090
Measurement of the Xi-p Scattering Cross Sections at Low Energy
In this paper we report cross-section measurements for elastic and
inelastic scatterings at low energy using a scintillating fiber active target.
Upper limit on the total cross-section for the elastic scattering was found to
be 24 mb at 90% confidence level, and the total cross section for the
reaction was found to be mb. We
compare the results with currently competing theoretical estimates.Comment: 9 page
Comparison of pain, cortisol levels, and psychological distress in women undergoing surgical termination of pregnancy under local anaesthesia versus intravenous sedation
<p>Abstract</p> <p>Background</p> <p>The weight of evidence suggests that women who freely choose to terminate a pregnancy are unlikely to experience significant mental health risks, however some studies have documented psychological distress in the form of posttraumatic stress disorder and depression in the aftermath of termination. Choice of anaesthetic has been suggested as a determinant of outcome. This study compared the effects of local anaesthesia and intravenous sedation, administered for elective surgical termination, on outcomes of pain, cortisol, and psychological distress.</p> <p>Methods</p> <p>155 women were recruited from a private abortion clinic and state hospital (mean age: 25.4 ± 6.1 years) and assessed on various symptom domains, using both clinician-administered interviews and self-report measures just prior to termination, immediately post-procedure, and at 1 month and 3 months post-procedure. Morning salivary cortisol assays were collected prior to anaesthesia and termination.</p> <p>Results</p> <p>The group who received local anaesthetic demonstrated higher baseline cortisol levels (mean = 4.7 vs 0.2), more dissociative symptoms immediately post-termination (mean = 14.7 vs 7.3), and higher levels of pain before (mean = 4.9 vs 3.0) and during the procedure (mean = 8.0 vs 4.4). However, in the longer-term (1 and 3 months), there were no significant differences in pain, psychological outcomes (PTSD, depression, self-esteem, state anxiety), or disability between the groups. More than 65% of the variance in PTSD symptoms at 3 months could be explained by baseline PTSD symptom severity and disability, and post-termination dissociative symptoms. Of interest was the finding that pre-procedural cortisol levels were positively correlated with PTSD symptoms at both 1 and 3 months.</p> <p>Conclusion</p> <p>High rates of PTSD characterise women who have undergone surgical abortions (almost one fifth of the sample meet criteria for PTSD), with women who receive local anaesthetic experiencing more severe acute reactions. The choice of anesthetic, however, does not appear to impact on longer-term psychiatric outcomes or functional status.</p
Recommendations for Enhancing Psychosocial Support of NICU Parents through Staff Education and Support
Providing psychosocial support to parents whose infants are hospitalized in the neonatal intensive care unit (NICU) can improve parents’ functioning as well as their relationships with their babies. Yet, few NICUs offer staff education that teaches optimal methods of communication with parents in distress. Limited staff education in how to best provide psychosocial support to families is one factor that may render those who work in the NICU at risk for burnout, compassion fatigue and secondary traumatic stress syndrome. Staff who develop burnout may have further reduced ability to provide effective support to parents and babies. Recommendations for providing NICU staff with education and support are discussed. The goal is to deliver care that exemplifies the belief that providing psychosocial care and support to the family is equal in importance to providing medical care and developmental support to the baby
Agricultural Productivity Growth, Efficiency Change and Technical Progress in Latin America and the Caribbean
Demographic, Behavioural and Normative Risk Factors for Gambling Problems Amongst Sports Bettors
- …