oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Caribou recovery and coexistence with introduced feral reindeer on the Nuussuaq Peninsula (70-71°N), West Greenland
Christine Cuyler
Rangifer , 2005,
Abstract: The small native caribou population (Rangifer tarandus groenlandicus) of Nuussuaq Peninsula was supplemented in 1968 with 10 semi-domestic reindeer (Rangifer tarandus tarandus). Hunting was prohibited in the early 1990s, but resumed with a quota of 100 animals in 1996 after the population was estimated to be around 400. Despite local criticism that herd size had increased, managers kept the estimate unchanged and permitted similar quotas for the next 5 years. To ascertain current status of the population, a late winter ground survey for minimum count, recruitment and distribution was done in April 2002 employing local hunters. Data collected included group size, location and animal sex/age. Only two age classes were used; calf (<1 year) and "adult" (>1 year). The 2002 ground survey observed 1164 individuals and a calf percentage of approximately 30%. The bull to cow ratio was 0.32. This data did not allow a calculation of population size, because areas where maximum animal numbers were expected were preferentially sampled. Spatial segregation of these two subspecies is suggested, given the observed and unexpected dissimilar behavior, pheno-type and spatial distribution. If true, then by 2002 feral reindeer had established a successful population, while native caribou had recovered to number several hundred. Genetic sampling is necessary to examine this hypothesis. At current late winter recruitment rates animal density could increase rapidly making both range expansion and genetic mixing likely in future. Since the total non-ice covered area available is about 6000 km2, greater caribou/reindeer densities may not be compatible with sustainable range use. Harvest quotas were increased in 2002 and 2003, and may reduce densities and preserve caribou range for the future.
Eigenvalue enclosures  [PDF]
Gabriel Raúl Barrenechea,Lyonell Boulton,Nabile Boussaid
Mathematics , 2013,
Abstract: This paper is concerned with methods for numerical computation of eigenvalue enclosures. We examine in close detail the equivalence between an extension of the Lehmann-Maehly-Goerisch method developed a few years ago by Zimmermann and Mertins, and a geometrically motivated method developed more recently by Davies and Plum. We extend various previously known results in the theory and establish explicit convergence estimates in both settings. The theoretical results are supported by two benchmark numerical experiments on the isotropic Maxwell eigenvalue problem.
BIOFILTERS IN AQUACULTURE
Ivo ?ari?,Marina Barilo,Ana Gavrilovi?,Jurica Jug-Dujakovi?
Ribarstvo : Croatian Journal of Fisheries , 2010,
Abstract: Recirculating aquaculture is one of the solutions to an environmentally sustainable and economically feasible aquaculture production, and can be established in either urban or rural communities. Controlled conditions enable optimal growth conditions suitable for the species in question during the whole growth process, as well as the shortening of the process itself, when compared to open uncontrolled systems. Recirculating systems are now one of the most researched fields of aquaculture, and biofiltration as the reduction of the poisonous ammonia compounds generated by digestion of proteins, is one of its most important parts. The aim of this study was to stress the importance of biofiltration, and to describe different designs of biofilters. Many biofilters are being used in commercial and research aquaculture facilities with differences in choice of working organism, design, material, price and etc. For the proper choice of biofilter it is necessary to know characteristics of each recirculating aquaculture system, because there are still no strict criteria for categorizing and applying different biofilter designs.
Effectiveness of Gel Repellents on Feral Pigeons  [PDF]
Birte Stock,Daniel Haag-Wackernagel
Animals , 2014, DOI: 10.3390/ani4010001
Abstract: Millions of feral pigeons ( Columba livia) live in close association with the human population in our cities. They pose serious health risks to humans and lead to high economic loss due to damage caused to buildings. Consequently, house owners and city authorities are not willing to allow pigeons on their buildings. While various avian repellents are regularly introduced onto the market, scientific proof of efficacy is lacking. This study aimed at testing the effectiveness of two avian gel repellents and additionally examined their application from animal welfare standpoint. The gels used an alleged tactile or visual aversion of the birds, reinforced by additional sensory cues. We mounted experimental shelves with the installed repellents in a pigeon loft and observed the behavior of free-living feral pigeons towards the systems. Both gels showed a restricted, transient repellent effect, but failed to prove the claimed complete effectiveness. Additionally, the gels’ adhesive effect remains doubtful in view of animal welfare because gluing of plumage presents a risk to feral pigeons and also to other non-target birds. This study infers that both gels lack the promised complete efficacy, conflict with animal welfare concerns and are therefore not suitable for feral pigeon management in urban areas.
Expanded concept of aquaculture  [PDF]
Melnikov Victor Nickolaevich,Melnikov Alexander Victorovich
Vestnik of Astrakhan State Technical University. Series: Fishing Industry , 2012,
Abstract: A new expanded definition of the concept "aquaculture" is offered; according to it aquaculture includes fishery, commercial fishing, processing of hydrobionts and ecology of aquaculture. The general concepts, the structure of aquaculture types and the major theoretical and applied problems are considered.
To Intervene or Not to Intervene? The Issue of the Liminal Feral Cat  [PDF]
Donna Yarri, Spencer S. Stober
Open Journal of Philosophy (OJPP) , 2019, DOI: 10.4236/ojpp.2019.92014
Abstract: The question of what responsibility humans have toward feral cats, if any, is a hotly contested one. Cats can be categorized in a number of ways: domesticated, stray, feral, and wild. However, of all these categories, feral cats are the most marginalized. Thus, they can pose a predicament for humans in terms of how or how not to care for them. Possible responses to this predicament range from leaving them alone; feeding them, but not neutering/spaying them; adopting a practice referred to as “trap, neuter, and release” (TNR), in which humans take responsibility for feeding cats, curbing their populations, and possibly monitoring their medical conditions; and even euthanizing them. This paper will provide an introduction to the issue of animal ethics in general and feral cats in particular; identify an ethical framework with which to address the issue of feral cats; explore the history of cat domestication; utilize a framework with which to examine the relationship of all cats to their environments; consider options for how to deal with feral cats in particular (TNR); explore and analyze data on TNR from the city of Philadelphia; and offer concrete solutions to the issue of the liminal feral cat.
Rigorous Enclosures of a Slow Manifold  [PDF]
John Guckenheimer,Tomas Johnson,Philipp Meerkamp
Mathematics , 2012, DOI: 10.1137/120861813
Abstract: Slow-fast dynamical systems have two time scales and an explicit parameter representing the ratio of these time scales. Locally invariant slow manifolds along which motion occurs on the slow time scale are a prominent feature of slow-fast systems. This paper introduces a rigorous numerical method to compute enclosures of the slow manifold of a slow-fast system with one fast and two slow variables. A triangulated first order approximation to the two dimensional invariant manifold is computed "algebraically". Two translations of the computed manifold in the fast direction that are transverse to the vector field are computed as the boundaries of an initial enclosure. The enclosures are refined to bring them closer to each other by moving vertices of the enclosure boundaries one at a time. As an application we use it to prove the existence of tangencies of invariant manifolds in the problem of singular Hopf bifurcation and to give bounds on the location of one such tangency.
Performance Evaluation for Museum Enclosures. Measurement, Modelling and Mitigation of Pollutant Impact on Objects in Museum Enclosures  [PDF]
Terje Gr?ntoft
E-Preservation Science , 2012,
Abstract: Results of measurement and modelling of pollutant gases inside and outside 11 enclosures used to protect exhibited objects in 10 European museums are presented. Monthly average values for ozone, nitrogen dioxide, formic and acetic acid, temperature and relative humidity inside the enclosures, and yearly average values for the pollutants inside and outside the enclosures are presented for each enclosure. An available pollution impact model was adapted to the use with enclosures. Model calculations are presented for the expected change in concentrations of the oxidizing: ozone and nitrogen dioxide, and acidic: acetic and formic acid, pollutants depending on possible change in the ventilation rate of the enclosures and on inclusion of active carbon absorber to reduce the concentrations. The modelling results are presented as the ‘impact concentration’ of the pollutants by weighing the measured concentrations with their respective recommended levels. In several of the enclosures a clear correlation was observed between temperature and/or relative humidity and the concentration of acetic and formic acid. The modelling showed that all of the enclosures protected against air pollutants, but that only one of the 11 enclosures satisfied the recommended level. The recommended level could be reached for all the enclosures by reducing the ventilation or including active carbon absorber to cover the floor area.
Comparison of the Fecal Microbiota in Feral and Domestic Goats  [PDF]
Kassandra M. De Jesús-Laboy,Filipa Godoy-Vitorino,Yvette M. Piceno,Lauren M. Tom,Ida G. Pantoja-Feliciano,Michelle J. Rivera-Rivera,Gary L. Andersen,María G. Domínguez-Bello
Genes , 2012, DOI: 10.3390/genes3010001
Abstract: Animals have co-evolved with mutualistic microbial communities, known as the microbiota, which are essential for organ development and function. We hypothesize that modern animal husbandry practices exert an impact on the intestinal microbiota. In this study, we compared the structure of the fecal microbiota between feral and domestic goats using the G2 PhyloChip and assessed the presence of five tetracycline resistance genes [ tet(M), tet(S), tet(O), tet(Q) and tet(W)] by PCR. Feces were collected from 10 goats: 5 domestic from a farm in the main island of Puerto Rico and 5 feral from the remote dry island of Mona. There were 42 bacterial phyla from 153 families detected in the goats’ feces. A total of 84 PhyloChip-OTUs were different in the fecal microbiota of feral and domestic goat. Both feral and domestic goats carried antibiotic resistance genes tet(O) and tet(W), but domestic goats additionally carried tet(Q). Diet, host genetics and antibiotic exposure are likely determinant factors in shaping the intestinal microbiota and may explain the differences observed between feral and domestic goats fecal microbiota.
A Scheme for Evaluating Feral Horse Management Strategies  [PDF]
L. L. Eberhardt,J. M. Breiwick
International Journal of Ecology , 2012, DOI: 10.1155/2012/491858
Abstract: Context. Feral horses are an increasing problem in many countries and are popular with the public, making management difficult. Aims. To develop a scheme useful in planning management strategies. Methods. A model is developed and applied to four different feral horse herds, three of which have been quite accurately counted over the years. Key Results. The selected model has been tested on a variety of data sets, with emphasis on the four sets of feral horse data. An alternative, nonparametric model is used to check the selected parametric approach. Conclusions. A density-dependent response was observed in all 4 herds, even though only 8 observations were available in each case. Consistency in the model fits suggests that small starting herds can be used to test various management techniques. Implications. Management methods can be tested on actual, confined populations.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.