4,303 research outputs found
Modelling hourly rates of evaporation from small lakes
The paper presents the results of a field study of open water evaporation carried out on three small lakes in Western and Northern Canada. In this case small lakes are defined as those for which the temperature above the water surface is governed by the upwind land surface conditions; that is, a continuous boundary layer exists over the lake, and large-scale atmospheric effects such as entrainment do not come into play. Lake evaporation was measured directly using eddy covariance equipment; profiles of wind speed, air temperature and humidity were also obtained over the water surfaces. Observations were made as well over the upwind land surface. <br><br> The major factors controlling open water evaporation were examined. The study showed that for time periods shorter than daily, the open water evaporation bears no relationship to the net radiation; the wind speed is the most significant factor governing the evaporation rates, followed by the land-water temperature contrast and the land-water vapour pressure contrast. The effect of the stability on the wind field was demonstrated; relationships were developed relating the land-water wind speed contrast to the land-water temperature contrast. The open water period can be separated into two distinct evaporative regimes: the warming period in the Spring, when the land is warmer than the water, the turbulent fluxes over water are suppressed; and the cooling period, when the water is warmer than the land, the turbulent fluxes over water are enhanced. <br><br> Relationships were developed between the hourly rates of lake evaporation and the following significant variables and parameters (wind speed, land-lake temperature and humidity contrasts, and the downwind distance from shore). The result is a relatively simple versatile model for estimating the hourly lake evaporation rates. The model was tested using two independent data sets. Results show that the modelled evaporation follows the observed values very well; the model follows the diurnal trends and responds to changes in environmental conditions
Are States with Larger than Average Black Populations Really the Worst Places to live in the USA? A Spatial Equilibrium Approach to Ranking Quality of Life
Quality-of-life rankings based on location-specific attributes/local amenities could induce elected official and policy makers into incorrectly constructing economic development plans if the ranking scheme was flawed. Hierarchical rankings of states in the USA in terms of quality-of-life that use an explicit amenity accounting method, typically assign lower ranks to states with large Black American populations. We show that these rankings utilize methodologies that are not based on economic theory, and that they arbitrarily construct ranking schemes about what individuals and firms value about the places where they locate. This pick-and-choose amenities accounting approach has its merits; however, we show that this approach introduces a bias into the ranking process. An alternative theoretically tenable and unbiased approach to measuring quality-of-life in particular locations follows from two important notions. First, a significant amount of what individuals and firms value in the places where they locate is unobservable. Secondly, the value of tangible and intangible location specific attributes (amenities) is captured by the difference between amenity-adjusted, housing prices and incomes. We implement a ranking scheme consistent with this notion, and find that when ranking states in the USA in terms of quality-of-life, states with large Black populations move up in the rankings substantially. Additionally, we find that relative to standard explicit amenity accounting quality-of-life measure, our spatial equilibrium measures can better explain the location choices of individuals, as measured by net migration
Synthesis and Crystal Structure of Tetrachloro (1,10-phenanthroline) platinum (IV)
We report the crystal structure determination of tetrachloro( l,10-phenanÂthroline)platinum(IV). X-ray data indicate there is little steric repulsion between the cx.-hydrogens on the phenanthroline ligand and the chloride ligands in the equatorial plane
Current Approaches to the Management of Acute Thoracolumbar Disc Extrusion in Dogs
Intervertebral disc extrusion (IVDE) is one of the most common neurologic problems encountered in veterinary clinical practice. The purpose of this manuscript is to provide an overview of the literature related to treatment of acute canine thoracolumbar IVDE to help construct a framework for standard care of acute canine thoracolumbar IVDE where sufficient evidence exists and to highlight opportunities for future prospective veterinary clinical research useful to strengthen care recommendations in areas where evidence is low or non-existent. While there exist a number of gaps in the veterinary literature with respect to standards of care for dogs with acute thoracolumbar IVDE, recommendations for standard care can be made in some areas, particularly with respect to surgical decompression where the currently available evidence supports that surgery should be recommended for dogs with nonambulatory paraparesis or worse. While additional information is needed about the influence on timing of decompression on outcome in dogs that are deep pain negative for longer than 48 h duration, there is no evidence to support treatment of the 48 h time point as a cut off beyond which it becomes impossible for dogs to achieve locomotor recovery. Surgical decompression is best accomplished by either hemilaminectomy or mini-hemilaminectomy and fenestration of, at a minimum, the acutely ruptured disc. Adjacent discs easily accessed by way of the same approach should be considered for fenestration given the evidence that this substantially reduces future herniation at fenestrated sites. Currently available neuroprotective strategies such as high does MPSS and PEG are not recommended due to lack of demonstrated treatment effect in randomized controlled trials, although the role of anti-inflammatory steroids as a protective strategy against progressive myelomalacia and the question of whether anti-inflammatory steroids or NSAIDs provide superior medical therapy require further evaluation
Is it feasible to detect bladder pressure from a cuff at the extradural sacral roots? Experiments in sheep.
Dogs with macroadenomas have lower body temperature and heart rate than dogs with microadenomas
Pituitary macroadenomas compress the hypothalamus, which partly regulates heart rate and body temperature. The aim of this study was to investigate whether heart rate and/or body temperature could aid in clinically differentiating dogs with macroadenomas from dogs with microadenomas (i.e. small non-compressive pituitary mass). Two groups of dogs diagnosed with pituitary-dependent hyperadrenocorticism (i.e. Cushing’s disease) were included. Heart rate and body temperature were collected on initial presentation before any procedure. Dogs with macroadenoma had a significantly lower heart rate and body temperature (P < 0.01) compared to dogs with microadenoma. We suggest that the combined cut-off values of 84 beats per minutes and 38.3 °C in dogs with Cushing’s disease, especially with vague neurological signs (nine of 12 dogs = 75%), might help to suspect the presence of a macroadenoma
Urinary Bladder Innervation Within the Sacral Roots of a Sheep
Managing the urinary bladder after spinal cord injury is of primary importance because neurogenic dysfunction leads to life-threatening complications. Sacral Anterior Root Stimulators that control the bladder have been available for many years, however, these devices cannot sense the fullness of the bladder or detect the onset of reflex voiding. In order to address this fundamental limitation, this paper explores the possibility of recording the neural signals that encode bladder fullness from the sacral roots in sheep using extra-neural books. Stimulation of and recording from six roots (S1, S2 and S3 bilaterally) shows that efferent and afferent pathways seem to be co-located within roots, but also that simultaneous recording from multiple roots may be useful to enhance overall signal quality
Urinary bladder innervation within the sacral roots of a sheep
Managing the urinary bladder after spinal cord injury is of primary importance because neurogenic dysfunction leads to life-threatening complications. Sacral Anterior Root Stimulators that control the bladder have been available for many years, however, these devices cannot sense the fullness of the bladder or detect the onset of reflex voiding. In order to address this fundamental limitation, this paper explores the possibility of recording the neural signals that encode bladder fullness from the sacral roots in sheep using extra-neural books. Stimulation of and recording from six roots (S1, S2 and S3 bilaterally) shows that efferent and afferent pathways seem to be co-located within roots, but also that simultaneous recording from multiple roots may be useful to enhance overall signal quality. </p
- …