scholarly journals PHOTOREACTIONS OF PARTIALLY BLINDED WHIP-TAIL SCORPIONS

1919 ◽  
Vol 1 (4) ◽  
pp. 435-458 ◽  
Author(s):  
Bradley M. Patten
Keyword(s):  
Relative Effectiveness ◽  
Normal Reaction ◽  
Sensitive Areas ◽  
Angular Deflection ◽  
Lateral Eye ◽  
Symmetrical Condition ◽  
Initial Path ◽  
Median Eyes

The experiments dealt with in this paper were devised to ascertain (1) the relative effectiveness as photoreceptors of the whip-tail scorpion's median eyes, lateral eye groups, and cutaneous sensitive areas, and (2) the effect on orientation produced by symmetrical and by asymmetrical interference with the photoreceptive mechanism. Each of the receptors was eliminated unilaterally and bilaterally, singly and in combinations with other receptors. In all, sixteen different abnormal conditions of the photoreceptive apparatus were produced. The reactions of animals thus partially blinded were measured in terms of angular deflection from an initial path of locomotion. Measurements obtained under anterior, lateral, and bilaterally balanced illumination were compared with measurements made on normal animals under the same conditions of illumination. The change from the normal reaction induced by covering a photoreceptor was taken as an index of the effectiveness of the receptor prevented from functioning. By comparing the values of the changes from normal reactions produced by the elimination of the several receptors, their relative effectiveness is approximated as median eyes : lateral eyes : cutaneous sensitive areas :: 1:1.6:2.2. All animals in which the receptive mechanism was rendered functionally asymmetrical exhibited, when subJected to bilaterally balanced illumination, deflections toward the side which had been made less sensitive. In a series of measurements made on animals in ten different conditions of asymmetry the amplitudes of the deflections were proportional to the degree of unbalance which had been produced in the photosensitive mechanism. Animals in which the receptive mechanism was reduced but left in a symmetrical condition maintained an undisturbed balance of reaction when subjected to equal, opposed lights. Under lateral or anterior illumination the rate of attaining a new direction of orientation was reduced in proportion to the extent of the interference with the receptive mechanism. The reactions of symmetrically and asymmetrically blinded scorpions indicate that orientation is attained and maintained by a transmission of impulses to the muscles of locomotion which is proportional bilaterally to the excitation of the symmetrically located photoreceptors. In their effect on orientation the three pairs of receptors are completely coordinated. Orientation depends upon bringing the excitation of the receptive mechanism as a whole into bilateral equilibrium.

scholarly journals Dual Sensitivities of Cells in Wolf Spider Eyes at Ultraviolet and Visible Wavelengths of Light

1972 ◽  
Vol 59 (3) ◽  
pp. 247-269 ◽  
Author(s):  
Robert D. DeVoe
Keyword(s):  
Visual Pigment ◽  
Wolf Spider ◽  
Intracellular Recordings ◽  
Visual Cells ◽  
Near Ultraviolet ◽  
Lateral Eye ◽  
Visible Wavelengths ◽  
Median Eyes ◽  
Anterior Median

Intracellular recordings have been made from visual cells in principal and secondary eyes of in vitro wolf spider preparations. The responses of all cells to all wavelengths of light were graded depolarizations; no hyperpolarizations or nerve discharges were seen. Cells in a secondary eye, the anterior lateral eye, had a maximum sensitivity in the visible at 510 nm and a secondary maximum, or shoulder, of sensitivity in the near ultraviolet at 380 nm. Cells in principal eyes, the anterior median eyes, all responded maximally both in the visible at 510 nm and in the ultraviolet at 360–370 nm or less. However, there was no typical ratio of ultraviolet to visible sensitivities; the differences in log sensitivities (log UV/VIS) varied from 3.3 to -0.5. Each principal eye had a population of cells with different ratios. These populations varied with the time of the year, possibly due to changes in light upon the animals. Chromatic adaptations of cells in anterior median (but not anterior lateral) eyes resulted in small, selective changes in spectral sensitivities, and there was some facilitation of responses from cells repeatedly stimulated. It is concluded that cells of secondary eyes contain only a visual pigment absorbing maximally in the visible, while cells of principal eyes probably contain variable amounts of both this pigment and one absorbing in the ultraviolet as well.

An Integrated Outflow-Spill Modeling Approach for Risk-Based Valve Placement of Liquid Transmission Pipelines

2008 ◽  
Author(s):  
Chuntao Deng ◽  
Patricia Zuczek ◽  
Keith Adams ◽  
Jim Mihell
Keyword(s):  
Cost Reduction ◽  
Relative Effectiveness ◽  
Three Dimensional ◽  
Weighted Average ◽  
Check Valve ◽  
Quantitative Risk Assessment ◽  
Maintenance Cost ◽  
Sensitive Areas ◽  
Valve Placement ◽  
Transmission Pipelines

Weir et al’s work [1] applied the relative effectiveness of outflow reduction to address the Intelligent Block Valve Placement (IVP) for liquid transmission pipelines. In their work, the effectiveness measure for each potential valve placement location is a length-weighted sum of the calculated volume reduction at all points along the pipeline in which the outflow volumes are multiplied by weighting factors that reflect the relative importance of spills in different sensitive areas; In our work, the original approach was enhanced to more quantitatively reflect both the likelihood of line failure and the full consequences of line failure as impacted by additional valve placement considering both block and check valves. This paper presents an IVP approach integrated with a quantitative risk assessment through which block and/or check valve placement schemes are optimized. The process involves a computer analysis in which block and check valves are iteratively selected and placed for each case. The risk reduction associated with each case is determined as the product of failure likelihood and the weighted average cost reduction. Failure likelihood is typically quantified using reliability methods or industry failure statistics, and is not the focus of this paper. The cost reduction focuses on environmental factors, which are represented by the clean-up cost of a spill that impacts both sensitive and non-sensitive areas for each incidence. In modeling consequence, the reduction of outflow potential is quantified by an in-house outflow simulation tool; and the potential spill impact is assessed through a mechanistic in-house VBA extension of ArcGIS, a three-dimensional (3-D) overland-hydrographical spill simulation package. Optimal valve placement design is achieved by balancing the costs associated with environmental risk with the costs associated with installing and maintaining block and check valves. The valves included in the assessment for outflow simulation and cost analysis are check valves and block valves. The automatic valve placement simulation is terminated when the valve installation/maintenance cost outweighs the benefits of placing more valves in the line.

Relative effectiveness of selected sunscreens

1970 ◽  
Vol 101 (4) ◽  
pp. 466-468 ◽  
Author(s):  
S. I. Katz
Keyword(s):  
Relative Effectiveness

An evaluation of a strategic de-stocking regime for dairying to improve nitrogen efficiency and reduce nitrate leaching from dairy farms in nitrate-sensitive areas

2000 ◽  
pp. 105-110
Author(s):  
Cecile De Klein ◽  
Jim Paton ◽  
Stewart Ledgard
Keyword(s):  
New Zealand ◽  
Nitrate Leaching ◽  
Management Practice ◽  
Field Measurements ◽  
Dairy Farms ◽  
Nitrogen Efficiency ◽  
Management Tool ◽  
Pasture Production ◽  
Leaching Losses ◽  
Sensitive Areas

Strategic de-stocking in winter is a common management practice on dairy farms in Southland, New Zealand, to protect the soil against pugging damage. This paper examines whether this practice can also be used to reduce nitrate leaching losses. Model analyses and field measurements were used to estimate nitrate leaching losses and pasture production under two strategic de-stocking regimes: 3 months off-farm or 5 months on a feed pad with effluent collected and applied back to the land. The model analyses, based on the results of a long-term farmlet study under conventional grazing and on information for an average New Zealand farm, suggested that the 3- or 5-month de-stocking could reduce nitrate leaching losses by about 20% or 35-50%, respectively compared to a conventional grazing system. Field measurements on the Taieri Plain in Otago support these findings, although the results to date are confounded by drought conditions during the 1998 and 1999 seasons. The average nitrate concentration of the drainage water of a 5-month strategic de-stocking treatment was about 60% lower than under conventional grazing. Pasture production of the 5-month strategic de-stocking regime with effluent return was estimated based on data for apparent N efficiency of excreta patches versus uniformlyspread farm dairy effluent N. The results suggested that a strategic de-stocking regime could increase pasture production by about 2 to 8%. A cost/ benefit analysis of the 5-month de-stocking system using a feed pad, comparing additional capital and operational costs with additional income from a 5% increase in DM production, show a positive return on capital for an average New Zealand dairy farm. This suggests that a strategic destocking system has good potential as a management tool to reduce nitrate leaching losses in nitrate sensitive areas whilst being economically viable, particularly on farms where an effluent application system or a feed pad are already in place. Keywords: dairying, feed pads, nitrate leaching, nitrogen efficiency, productivity, strategic de-stocking

RELATIVE EFFECTIVENESS OF ACTH GIVEN BY SINGLE, DIVIDED AND CONTINUOUS INJECTION

1951 ◽  
Vol 6 (1) ◽  
pp. 90-96 ◽  
Author(s):  
A. QUERIDO ◽  
A. KASSENAAR ◽  
J. GOSLINGS ◽  
W. HYMANS
Keyword(s):  
Relative Effectiveness ◽  
Continuous Injection
Sign in / Sign up

Export Citation Format

Share Document