782 research outputs found
Wolves in rural agricultural areas of western North America: conflict and conservation
No full textNo abstract available for this chapte
Reclamation Outcomes on Energy Disturbances in Silver Sagebrush Communities
No full textBibliography: p. 255-272Some pages are in colour
Toward monitoring the effectiveness of visitor management in the Beach Ridge tundra ecosystem of Wapusk National Park, Manitoba
No full textBibliography: p. 155-16
Susa Young Gates
No full textSusa Young Dunford Gates is shown with her daughters Emma Lucy and Leah Dunford. Susa was a prominent Utah woman, author, and a daughter of Brigham Young
Annual migrations of female prairie rattlesnakes, Crotalus v. viridis, in Alberta.
No full textBibliography: p. 53-61Some pages are in colour
Review of photonic Hilbert transformers
No full textThis paper reviews the demonstrations of photonic Hilbert transformers (PHTs), describing their progress and recent developments. The physical operating principles of PHTs including fractional Hilbert transformers are discussed, together with device applications in all-optical signal processing. Versatile approaches to realize PHTs are discussed, e.g., discrete free space optics, fiber-based schemes and integrated planar geometry. The numerical designs and experimental performances of these PHTs are analyzed in terms of spectral quality, operating bandwidth, system integration, and mechanical and thermal stability. Recent developments of the monolithically integrated photonic Hilbert transform (HT) devices include directional couplers and planar Bragg gratings which allow all-optical single-sideband (SSB) suppression and sideband switching.Erratum: The author of Ref. [1] Frederick W K should be King F W
Effects of surface states on control characteristics of nano-meter scale Schottky gates formed on GaAs
No full textEffects of surface states on gate control characteristics of nano-meter scale Schottky gates formed on GaAs are investigated both theoretically and experimentally. Special sample structures are used. They are metal–insulator–semi-conductor structures having nano-meter scale Schottky dot arrays for capacitance–voltage (C–V) measurements and metal–semi-conductor field effect transistor structures having nano-meter scale grating Schottky gates for current–voltage (I–V) measurements. Measured C–V and I–V results are compared with results of theoretical calculation on a computer.
The effects of surface states are found to be two-fold. Namely, it is shown that control characteristics of nano-meter scale Schottky gates are strongly degraded by the presence of Fermi level pinning caused by surface states on the free surface surrounding the gate. It is also shown that a significant amount of gate-induced lateral charging of surface states takes place around the gate periphery, effectively increasing the gate dimension. These results indicate the critical importance of control of surface states in nano-devices using nano-meter scale Schottky gates
A conceptual model of tuberculosis transmission risk in free-ranging bison herds of northern Canada
No full textTuberculosis transmission in free-ranging bison of northern Canada is of significant
concern to wildlife managers because of its effects on condition and mortality in bison herds and
the potential for transmission to local hunters and neighbouring cattle populations. The chronic
nature of tuberculosis combined with the gregarious behaviours of bison permit its persistence in
free-ranging herds even at low densities, which makes disease eradication difficult without
whole herd depopulation. The protection of remaining non-infected free-ranging bison
populations is thus of paramount importance to the conservation of specific disease-free wild
bison in northern Canada and to the economic stability of cattle farms. Detection of movements
and removal of dispersing animals between spatially separated free-ranging populations reduces
the potential for contact between bison populations and minimizes the probability of tuberculosis
transmission. In this thesis, a conceptual model was developed to assess the potential for
tuberculosis transmission between two infected bison herds (Nyarling River and Garden River)
in Wood Buffalo National Park and the spatially separated, Mackenzie Bison herd in the
Northwest Territories. This conceptual model identifies gaps in knowledge and highlights areas
where research is required to ensure accurate evaluation of tuberculosis transmission risk in freeranging
bison. The main finding was that the bison cohort representing the highest risk for
tuberculosis transmission between spatially separated free-ranging herds is mature males. The
propensity of mature males to make long-distance movements is also not fully understood and
research to predict these movements would make a significant contribution to risk assessment
and management planning to reduce the probability of contact between infected and non-infected
bison populations
Wolf Depredation Trends and the Use of Fladry Barriers to Protect Livestock in Western North America
No full textIn Alberta, Canada (1982-2001), and in Idaho, Montana, and Wyoming, United States (1987-2001), wolves (Canis lupus) killed various domestic animals, among which the major prey were sheep in the United States (68%, n = 494) and cattle in Canada (95%; n = 1633). Under recovery programs, the wolf population increased in the United States, and depredation events increased proportionately. In both countries, the number of domestic animals killed each year was correlated with the number of wolves killed by government authorities for depredation management. We tested the ability of anti-wolf barriers made of flags hanging from ropes to impede wolf access to food and livestock. In 18 experiments, barriers prevented captive wolves (n = 9) from accessing food for up to 28 hours and allowed daily separation of wolves to administer contraceptive pills to a female wolf. Barriers prevented access by wild wolves to 100-m2 baited sites during two 60-day tests. We also set barriers around three cattle pastures. In Alberta during two 60-day trials on 25-ha pastures, wolves approached barriers on 23 occasions but did not cross them, and no cattle were killed. Wolves killed cattle on neighboring ranches during the trials and before and after the trials on the tested ranches. In Idaho four radio-collared wolves crossed barriers and killed cattle in a 400-ha ranch after 61 days of barrier exposure. Our results suggest that anti-wolf barriers are effective in deterring captive and wild wolves for \u3e1 and ≥60 days, respectively, and that wild wolves switch to alternative livestock when excluded from one herd of livestock. Our depredation data indicate that protecting livestock from wolves reduces the necessity for killing wolves. Barriers could play a role among the limited set of preventive measures available and offer a cost-effective mitigation tool for the problem of livestock depredation on a local scale
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