Nutrient limitation in the Chesapeake Bay : nutrient bioassays in the Virginia Bay system: final report

Nutrient enrichment bioassays were conducted on water samples collected from six stations in the Virginia portion of the Chesapeake Bay system on a monthly basis over a year. Two stations were located in the tidal freshwater portions of the Rappahannock and James Rivers, at the mouths of these rivers and in the mainstem of the Bay. The purpose of the experiments was to determine the spatial and temporal pattern of nutrient limitation of phytoplankton growth

A Macrophage Phenotype for a Constitutive, Class II Antigen-Expressing, Human Dermal Perivascular Dendritic Cell

A previously uncharacterized population of class II antigen-bearing dendritic cells that are intimately associated with the dermal microvasculature was identified in normal human skin using a double-label, indirect immunofluorescence technique. The only other major HLA-DR positive dermal cell type noted in these studies, the dermal microvascular endothelial cell (DMVEC), appeared to express lesser amounts of HLA-DR region gene product than did this dermal perivascular dendritic cell (DPDC). These DPDC were particularly common around small vessels in the superficial vascular plexus of the papillary dermis and were distinct from the mast cell, another cell type normally seen in a similar location. Phenotypic and ultrastructural studies have determined that the DPDC is more closely related to the monocyte/macro-phage lineage than the dendritic cell lineage. The perivascular location and phenotype of this cell distinguishes it from other previously described constitutive dermal cell types such as the classic “histiocyte,” veiled cell, and dendrocyte. The relatively rich expression of all three major HLA-D region gene products by this dermal perivascular dendritic macro-phage would suggest that it could play a significant role in the immunobiology of the dermal microvascular unit

Depression in Right Hemisphere Disorder

Between 25-79% of stroke survivors suffer depression, which can lead to limited recovery, decreased quality of life, and increased mortality. In adults with right hemisphere disorder (RHD), the cause(s) of depression have been unclear. Our results showed that significantly more adults with RHD were depressed than normal controls, and that adults with RHD were significantly more depressed than normal controls. In both groups, depression was significantly related with loneliness. In adults with RHD, depression was also significantly related with social support. No demographic or lesion-related variables were associated with increased depression in our samples. Suggestions for treatment research are offered

Risk Factors for Depression in Aphasia: Clinical Implications

Between 25-79% of stroke survivors suffer depression, which can limit recovery, decrease quality of life, and increase mortality. In adults with aphasia, the cause(s) of depression, and thus the means by which it can be addressed, have been unclear. Our participants with aphasia did not differ from our normal controls in presence or severity of depression. However, possible causes of depression differed between groups. In both groups, loneliness was a significant factor. In adults with aphasia, other significant factors were time poststroke, severity of language impairment, and desired control over every day events. Suggestions for research and treatment are offered

ADH Levels during Salt Depletion in Dogs *

Two groups of trained dogs were subjected to sodium chloride depletion and plasma ADH concentration, renin activity, plasma sodium, plasma osmolality, blood volume, hematocrit and body weight were measured. In one group of animals, sodium depletion was created by restricting intake to 5 mEq/24 h. Despite a statistically significant decrease in body weight and blood volume and a corresponding increase in plasma renin activity, plasma ADH concentration was not seen to change significantly from control values. Similar findings were seen in a second group of dogs which were given a diuretic in addition to dietary sodium restriction. In these animals the decrease in blood volume and rise in plasma renin activity were proportionately greater. Plasma ADH concentration was not observed to change significantly in this group of animals either. Both groups of animals developed significant hyponatremia during the experiment. It is concluded that in these dogs, the secretion of ADH was not suppressed and consequently hyponatremia developed. It is suggested that endogenous angiotensin was responsible for the continued secretion of ADH at control levels.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75034/1/j.1365-2362.1971.tb00567.x.pd

Gravitational shear, flexion, and strong lensing in Abell 1689

We present a gravitational lensing analysis of the galaxy cluster Abell 1689, incorporating measurements of the weak shear, flexion, and strong lensing induced in background galaxies. This is the first time that a shapelet technique has been used to reconstruct the distribution of mass in this cluster and the first time that a flexion signal has been measured using cluster members as lenses. From weak shear measurements alone, we generate a nonparametric mass reconstruction, which shows significant substructure corresponding to groups of galaxies within the cluster. In addition, our galaxy-galaxy flexion signal demonstrates that the cluster galaxies can be well fit by a singular isothermal sphere model with a characteristic velocity dispersion of σv = (295 ± 40) km s^(-1). We identify a major, distinct dark matter clump, offset by 40 h^(-1) kpc from the central cluster members, which was not apparent from shear measurements alone. This secondary clump is present in a parametric mass reconstruction using flexion data alone, and its existence is suggested in a nonparametric reconstruction of the cluster using a combination of strong and weak lensing. As found in previous studies, the mass profile obtained by combining weak and strong lensing data shows a much steeper profile than that obtained from only weak lensing data

Energy Spectrum Evolution of a Diffuse Field in Elastic Body Caused by Weak Nonlinearity

We study the evolution of diffuse elastodynamic spectral energy density under the influence of weak nonlinearity. It is shown that the rate of change of this quantity is given by a convolution of the linear energy at two frequencies. Quantitative estimates are given for sample aluminum and fused silica blocks of experimental interest.Comment: 9 pages, 3 figures; revised for better presentatio