3,314 research outputs found
Evaluation of Dimethyl Anthranilate as a Nontoxic Starling Repellent for Feedlot Settings
Few objective estimates are available, but starling (Sturnus uulgaris) and, sometimes, blackbird (e.g., Agelaius phoeniceus) depredations at feedlots are considered serious economic problems (Besser et al. 1967, 1968; Feare 1975, 1980; Stickley 1979; Twedt and Glahn 1982). Losses may result either from feed contamination and disease transmission or, more likely, from feed consumption (Besser et al. 1968; Russell 1975; Twedt and Glahn 1982). These problems are exacerbated by the use of complete diets (Rickaby 1978) which are presented in open troughs to which starlings have access. Feare and Wadsworth (1981) have shown that these birds can take up to 9% of the high protein fraction of the diet, thus depriving cattle of their high energy source and altering the composition of the entire ration. Efforts to control problem birds at feedlots have focused mainly on attempts to trap or kill birds with mechanical devices or chemical agents (Besser et al. 1967; Bogadich 1968; Levingston 1967; Westetal.1967; Feareetal.1981). These approaches, however, fail to create a suboptimal environment for avian feeding activity, and birds rapidly reinfest feedlots when control measures are relaxed (Twedt and Glahn 1982). Additional problems arise when lethal chemicals; such as Starlicide (1% C-chloro-p-toludine hydrochloride on poultry pellets) are used, including: (1) potential primary and secondary hazards to nontarget animals (e.g., Cunningham, 1979), (2) bait aversion by target birds, (3) expense and labor in prebaiting, baiting and monitoring (Glahn 1981) and (5) rather short-term effectivenses when large numbers of birds are in the area (Feare et al. 1981)
Studies in physiological undernourishment in sheep
1. An examination of changes in weight and body composition in
a flock of free -grazing Scottish Blackface ewes indicated
that, during the greater part of pregnancy, these ewes were
undernourished and catabolizing considerable amounts of
body tissue.2. The nutritional states of ewes from two differently managed
Scottish Blackface flocks were characterized during late
pregnancy in terms of circulating concentrations of plasma
free fatty acids and ketones. Marked undernourishment was
evident in both situations.3. Data collected in a variety of situations supported the
hypothesis that the severity of undernourishment during late
pregnancy is determined principally by foetal weight and the
level of food intake. Within a group of pregnant ewes with
comparable intakes, the general degree of undernourishment is
dependent on the level of intake, and the relative severity
of undernourishment in individual animals is determined by
differences in foetal weight.4. The use of certain biochemical parameters as indices of undernourishment was examined in ewes with artificially induced
hypoglycaemia. It was concluded that nutritional state is
best characterized in terms of that parameter which shows the
greatest response per unit change in either nutrient intake
or nutrient requirement.5. Biochemical parameters were used to control the nutritional states of individual animals in an experiment on the effects of undernourishment during pregnancy on lamb
birth- weight. The results of this experiment indicated
that the undernourishment occurring in free- grazing hill
ewes during late pregnancy was likely to reduce the birth - weight of single lambs by 10%, and that of twins by 25%.6. The additional energy requirements during pregnancy were
estimated to be 100g digestible organic matter per kg
foetus
Electrophoresis of a polyelectrolyte through a nanopore
A hydrodynamic model for determining the electrophoretic speed of a
polyelectrolyte through a nanopore is presented. It is assumed that the speed
is determined by a balance of electrical and viscous forces arising from within
the pore and that classical continuum electrostatics and hydrodynamics may be
considered applicable. An explicit formula for the translocation speed as a
function of the pore geometry and other physical parameters is obtained and is
shown to be consistent with experimental measurements on DNA translocation
through nanopores in silicon membranes. Experiments also show a weak dependence
of the translocation speed on polymer length that is not accounted for by the
present model. It is hypothesized that this is due to secondary effects that
are neglected here.Comment: 5 pages, 2 column, 2 figure
Moderating effects of service separation on customer relationships with service firms: A social-exchange perspective
Purpose: The purpose of this paper is to examine the impact of service separation on the ability of service firms to build and maintain customer relationships, by exploring the differences in the strength of interrelationships among key relational constructs between separated and unseparated service delivery modes. Design/methodology/approach: A field survey was conducted with retail banking customers in Saudi Arabia (n=592) using a structured self-administered questionnaire consisting of well-established scales. Data were analyzed using AMOS 24. Findings: Service separation negatively moderates (weakens) the ability of the service firms to leverage their social benefits, relational trust and affective commitment to increase customer loyalty and to strengthen overall customer relationships. Research limitations/implications: This study uses retail banking customers in Saudi Arabia to test the impact of service separation in their relationship with the bank; hence, its findings may not be generalizable to other types of services and cultural settings. Practical implications: Service firms using online and mobile technologies should be aware that trust and commitment remain key to building customer loyalty. Hence, the trade-off between the benefits of these technologies and their negative impact on customer relationship needs to be factored into managerial decision making. Originality/value: The paper highlights the importance of maintaining face-to-face interactions with service customers to create robust relationships that yield loyalty, despite the growing popularity of online and mobile technologies
Test results of a 60 volt bipolar nickel-hydrogen battery
In July, l986, a high-voltage nickel-hydrogen battery was assembled at the NASA Lewis Research Center. This battery incorporated bipolar construction techniques to build a 50-cell stack with approximately 1.0 A-hr capacity (C) and an open-circuit voltage of 65 V. The battery was characterized at both low and high current rates prior to pulsed and nonpulsed discharges. Pulse discharges at 5 and 10 C were performed before placing the battery on over 1400, 40% depth-of-discharge, low-earth-orbit cycles. The successful demonstration of a high-voltage bipolar battery in one containment vessel has advanced the technology to where nickel-hydrogen high-voltage systems can be constructed of several modules instead of hundreds of individual cells
Component variations and their effects on bipolar nickel-hydrogen cell performance
A 50 cell bipolar nickel-hydrogen battery was assembled to demonstrate the feasibility of constructing a high voltage stack of cells. Various component combinations were tested in this battery. The battery had approximately 1 ampere-hour of capacity and was constructed from components with an active area of 2" X 2". The components were parametrically varied to give a comparison of nickel electrodes, hydrogen electrodes, separators, fill procedures and electrolyte reservoir plate thicknesses. Groups of five cells were constructed using the same components; ten combinations were tested in all. The battery was thoroughly characterized at various change and discharge rates as well as with various pulse patterns and rates. Over a period of 1400 40% DOD LEO cycles some of the groups began to exhibit performance differences. In general, only separator variations had a significant effect on cell performance. It also appears that shunt currents may have been operating within the stack, resulting in electrolyte transfer from one cell to another, thus contributing to cell performance variations
Surface-mediated attraction between colloids
We investigate the equilibrium properties of a colloidal solution in contact
with a soft interface. As a result of symmetry breaking, surface effects are
generally prevailing in confined colloidal systems. In this Letter, particular
emphasis is given to surface fluctuations and their consequences on the local
(re)organization of the suspension. It is shown that particles experience a
significant effective interaction in the vicinity of the interface. This
potential of mean force is always attractive, with range controlled by the
surface correlation length. We suggest that, under some circumstances,
surface-induced attraction may have a strong influence on the local particle
distribution
Colloidal Electrostatic Interactions Near a Conducting Surface
Charge-stabilized colloidal spheres dispersed in deionized water are supposed
to repel each other. Instead, artifact-corrected video microscopy measurements
reveal an anomalous long-ranged like-charge attraction in the interparticle
pair potential when the spheres are confined to a layer by even a single
charged glass surface. These attractions can be masked by electrostatic
repulsions at low ionic strengths. Coating the bounding surfaces with a
conducting gold layer suppresses the attraction. These observations suggest a
possible mechanism for confinement-induced attractions.Comment: 4 pages, 2 figure
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