294,498 research outputs found
Toxic Phenolic Glycosides From \u3ci\u3ePopulus:\u3c/i\u3e Physiological Adaptations of the Western North American Tiger Swallowtail Butterfly, \u3ci\u3ePapilio Rutulus\u3c/i\u3e (Lepidoptera: Papilionidae)
The phenolic glycosides tremulacin and salicortin found in quaking aspen, Populus tremuloides, and other members of the Salicaceae, are known to be toxic to larvae of the Eastern tiger swallowtail butterfly, Papilio glaucus, but not to the Canadian tiger swallowtail, P. canadensis. Larvae of the western tiger swallowtail, P. rutulus, were not killed nor were their growth rates suppressed when fed a mixture of tremulacin and salicortin on black cherry leaves. When the Salicaceae adapted P. rutulus penultimate instar larvae were fed a combination of the two phenolic glycosides and the esterase inhibitor (DEF S,S,S-tributylphosphorotrithioate), growth was reduced more than 50OJo compared to controls, and half of the larvae died before completing the instaL Our results indicate that esterase detoxification mechanisms are involved in the western tiger swallowtail, P. rutulus, as is also known to be the case for the northern tiger swallowtail, P. canadensis. It is not known whether the same esterase isozyme is involved in both species. From an evolutionary perspective such information could help resolve whether the Salicaceae-adapted swallowtails species are a monophyletic group (perhaps due to isolation in the Beringial Pleistocene glacial refuge of Alaska)
An evaluation of mark and recapture techniques for estimating tigerfish biomass in Lake Kariba
The effectiveness of 2 mark and recapture techniques was evaluated using tiger fish, Hydrocynus vittatus. The 2 techniques used were: tagging with a plastic tag and fluorescent spray marking. While the tagging method resulted as the logical method to use within the constraints of the tiger fish study, it cannot be considered completely reliable for the estimation of population size in Lake Kariba
A testsuite for testing parser performance on complex German grammatical constructions [TePaCoC - a corpus for testing parser performance on complex German grammatical constructions]
Traditionally, parsers are evaluated against gold standard test data. This can cause problems if there is a mismatch between the data structures and representations used by the parser and the gold standard. A particular case in point is German, for which two treebanks (TiGer and TüBa-D/Z) are available with highly different annotation schemes for the acquisition of (e.g.) PCFG parsers. The differences between the TiGer and TüBa-D/Z annotation schemes make fair and unbiased parser evaluation difficult [7, 9, 12]. The resource (TEPACOC) presented in this paper takes a different approach to parser evaluation: instead of providing evaluation data in a single annotation scheme, TEPACOC uses comparable sentences and their annotations for 5 selected key grammatical phenomena (with 20 sentences each per phenomena) from both TiGer and TüBa-D/Z resources. This provides a 2 times 100 sentence comparable testsuite which allows us to evaluate TiGer-trained parsers against the TiGer part of TEPACOC, and TüBa-D/Z-trained parsers against the TüBa-D/Z part of TEPACOC for key phenomena, instead of comparing them against a single (and potentially biased) gold standard. To overcome the problem of inconsistency in human evaluation and to bridge the gap between the two different annotation schemes, we provide an extensive error classification, which enables us to compare parser output across the two different treebanks. In the remaining part of the paper we present the testsuite and describe the grammatical phenomena covered in the data. We discuss the different annotation strategies used in the two treebanks to encode these phenomena and present our error classification of potential parser errors
Geometry modeling and multi-block grid generation for turbomachinery configurations
An interactive 3D grid generation code, Turbomachinery Interactive Grid genERation (TIGER), was developed for general turbomachinery configurations. TIGER features the automatic generation of multi-block structured grids around multiple blade rows for either internal, external, or internal-external turbomachinery flow fields. Utilization of the Bezier's curves achieves a smooth grid and better orthogonality. TIGER generates the algebraic grid automatically based on geometric information provided by its built-in pseudo-AI algorithm. However, due to the large variation of turbomachinery configurations, this initial grid may not always be as good as desired. TIGER therefore provides graphical user interactions during the process which allow the user to design, modify, as well as manipulate the grid, including the capability of elliptic surface grid generation
The Maghreb – one more important biodiversity hot spot for tiger beetle fauna (Coleoptera, Carabidae, Cicindelinae) in the Mediterranean region
The tiger beetle fauna of the Maghreb region is one of the richest in the Palaearctic, including 22 species
and 5 subspecies and 19% of all Palaearctic species of Cicindelinae. Assembled by their chorotypes, the
Maghreb tiger beetles fall into eight different groups that include Maghreb endemics (26% of fauna),
Mediterranean (7%), West Mediterranean (40%), North African (4%), Mediterranean-Westturanian
(4%), West Palaearctic (4%), Afrotropico-Indo-Mediterranean (4%), and Saharian (11%) species. The
Mediterranean Sclerophyl and Atlas Steppe are the Maghreb biogeographical provinces with the highest
species richness, while the Sahara Desert has the lowest Cicindelinae diversity. Twenty-five cicindelid species
and subspecies (93% of Maghreb fauna) are restricted to only one or two habitat types in lowland
areas. Only Calomera littoralis littoralis and Lophyra flexuosa flexuosa are recognized as eurytopic species and
occur in three types of habitat. The highest tiger beetle diversity characterizes salt marshes and river banks
(in both cases 11 species and subspecies or 41% of Maghreb fauna). Approximately 85% of all Maghreb
tiger beetle species and subspecies are found in habitats potentially endangered by human activity
Estimating the potential impact of canine distemper virus on the Amur tiger population (Panthera tigris altaica) in Russia
Lethal infections with canine distemper virus (CDV) have recently been diagnosed in Amur tigers (Panthera tigris altaica), but long-term implications for the population are unknown. This study evaluates the potential impact of CDV on a key tiger population in Sikhote-Alin Biosphere Zapovednik (SABZ), and assesses how CDV might influence the extinction potential of other tiger populations of varying sizes. An individual-based stochastic, SIRD (susceptible-infected-recovered/dead) model was used to simulate infection through predation of infected domestic dogs, and/or wild carnivores, and direct tiger-to-tiger transmission. CDV prevalence and effective contact based on published and observed data was used to define plausible low- and high-risk infection scenarios. CDV infection increased the 50-year extinction probability of tigers in SABZ by 6.3% to 55.8% compared to a control population, depending on risk scenario. The most significant factors influencing model outcome were virus prevalence in the reservoir population(s) and its effective contact rate with tigers. Adjustment of the mortality rate had a proportional impact, while inclusion of epizootic infection waves had negligible additional impact. Small populations were found to be disproportionately vulnerable to extinction through CDV infection. The 50-year extinction risk in populations consisting of 25 individuals was 1.65 times greater when CDV was present than that of control populations. The effects of density dependence do not protect an endangered population from the impacts of a multi-host pathogen, such as CDV, where they coexist with an abundant reservoir presenting a persistent threat. Awareness of CDV is a critical component of a successful tiger conservation management policy
Spectacular Tropes: Representations of the Roman Arena
This paper will focus on the construction of representational tropes depicting the ancient Roman arenas and those involved with them, particularly within the spectacles of gladiatorial battles. The conceptions of representation within the arena influenced how differing Roman social groups perceived one another through social ideals and identities. I will analyze this by looking at three major methods of representation from the ancient Roman world: (1) literary sources, (2) epigraphical materials (inscriptions and graffiti), and (3) visual sources (mosaics and reliefs). These sources reflect the different characteristics of the Roman arenas and are defined by various social contexts, displaying how different ideals relating to the arena and its performers were valued within greater Roman society. I will examine these ancient ideals on representation by relating them to anthropological and sociological concepts related to the representation and public perceptions of athletes and sports. This includes representations of the body, masculine ideals, social status, and others
Tiger, tiger burning bright:is tourism a blessing or a blight?
The number of tigers have declined from 100,000 a century ago to only c3,200 today and are thus a focus for conservation and last-chance tourism. However tiger watching tourism is seen as another pressure on their survival and thus India has been the first country to announce plans to reduce/regulate tourism in its tiger reserves. This has re-opened an international discussion on whether tourism is a positive or negative force for the conservation of flagship species. Using India as a case study, this paper sets out the arguments for tiger tourism in order to invite further academic and industry comment
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