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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Accommodating surprise in taxonomic tasks : a psychological and computational investigation

Alberdi, Eugenio January 1996 (has links)
This thesis reports psychological and computational research conducted in a scientific domain: plant taxonomy. The purpose of the investigation was to explore how expert scientists cope with puzzling observations. Firstly, a psychological study of category induction was conducted to investigate the procedures used by professional botanists as they tried to identify a botanical category from a set of positive and negative instances. The target category in the study was defined by a feature which was unusual and inconsistent with subjects' botanical knowledge; consequently, situations of uncertainty and puzzlement were generated. The verbal reports elicited by the subjects, as they were working through the categorisation tasks, were recorded and analysed. The analysis of the protocols indicated that, in order to cope with conflicting evidence, the botanists heavily relied on their expert knowledge, which intricately influenced their inductive procedures (i.e. observation and comparison of instances). These results are consistent with previous categorisation studies which looked at the effects of background knowledge in concept induction. However, the role of background knowledge had not been sufficiently stressed in earlier investigations of scientists' reactions to surprise. The psychological results were simulated in a computer programme, Proto-ReTAX, which reproduced the categorisation behaviour of some of the subjects during the study. Some of the mechanisms implemented in this programme were subsequently used in ReTAX, an artificial intelligence system for taxonomy revision. Using a set of consistency checking rules and a set of refinement operators, ReTAX succeeded in replicating taxonomic revisions which had been suggested by professional botanists for the botanical family Ericaceae.

A naturalistic model of classification and its relevance to some controversies in botanical systematics, 1900-1950

Dean, John Philip January 1980 (has links)
There is currently considerable controversy within philosophy over how a natural kind term's extension is determined. Adherents to traditional theories of meaning argue that extension is determined by intensional properties which usually consist of identifying descriptions. Recently a new, essentialist alternative to these traditional accounts has been advocated; proponents of this view maintain that a term's extension includes all objects which are essentially the same as a given paradigm instance of the term's use. In the present thesis it is argued that both description theories and essentalism describe not how classification must proceed but rather two alternative strategies for how a classification of natural kinds might be attempted. A term's extension is not determined in advance by either identifying descriptions or hidden essential properties since stress on either of these is itself a choice. This claim is exemplified by using empirical material drawn from the recent (post 1900) history of a classifictory science, botanical systematics. By means of this evidence it is shown that both "descriptionist" and "essentialist" strategies of concept application have been (and still are) pursued by different groups of taxonomists. One consequence of the position outlined above is that classifications are conventions and that they are evaluated instrumentally. The force of this argument is best illustrated by conceiving of classifications as part of a wider network of beliefs which are socially transmitted and sustained. Changes in networks are designed to further the interests to which a network is being put. It is argued here that the main kinds of interests which have been important in twentieth century systematics are 1) interests in technical prediction and control and 2) professional vested interests. An important aspect of both these kinds of interests is that they are normally considered to be "internal" to science. It follows that to understand scientific knowledge from a sociological perspective does not, of necessity, entail commitment to "external" explanations of scientific change.

Presenting an alternative source code plagiarism detection framework for improving the teaching and learning of programming

Hattingh, F, Buitendag, AK, van der Walt, JS 01 January 2003 (has links)
Abstract The transfer and teaching of programming and programming related skills has become, increasingly difficult on an undergraduate level over the past years. This is partially due to the number of programming languages available as well as access to readily available source code over the Web. Source code plagiarism is common practice amongst many undergraduate students. This practice has a detrimental effect on the presentation of specific content relating to introduction to programming courses. One of the problems identified in the research conducted is that turnaround time with relation to assessment and feedback, which are presented to the students, is a critical factor in the subsequent success rates of the subject. This paper investigates, utilizing a literature review, how plagiarism detection metrics and a framework for providing effective feedback to students and educators could be implemented to enhance the teaching and learning processes. The predominant technique used for detecting plagiarism is to evaluate how a piece of source code was constructed over time. By analyzing the students’ programming patterns, lectures can be adapted to address problem areas and react accordingly. The paper also provides an overview of current metrics used for plagiarism detection and suggests ways of improving the process by including enhanced techniques for the gathering of metrics over time as well as suggesting ways to use the metrics to aid learning on all cognitive levels. Some of the key considerations presented as part of this research include effective feedback mechanisms and real-time responses to plagiarism as well as contributing towards learning on different cognitive levels.

Molecular systematics of the galliformes, with particular reference to the endemic Vietnamese Gallopheasants (Lophura) and the Green Peafowl (Pavo muticus)

Scott, Euan Andrew January 1999 (has links)
No description available.

Cladistic analysis of Macrobunidae Petrunkevitch, 1928 new rank and revision of Macrobuninae (Araneae). / Análise cladística de Macrobunidae Petrunkevitch 1928 stat. nov. e revisão de Macrobuninae (Araneae)

Almeida-Silva, Lina Maria 26 August 2013 (has links)
Macrobuninae Petrunkevitch is revised and submitted to a cladistic analysis. Macrobuninae, once considered the biggest Amaurobiidae Thorell subfamily is now proved to be not even closely related to Amaurobiinae, the \"true amaurobiids\". Our matrix, composed by 82 terminal taxa and 107 characters, includes representatives of all Macrobuninae genera and new taxa we believed to be part of Macrobuninae. As out-groups, we included representatives of the families Agelenidae Koch, Amaurobiidae, Amphinectidae Forster & Wilton, Chummidae Jocqué, Desidae Pocock, Dictynidae O. P.-Cambridge, Phyxelididae Lehtinen, Stiphidiidae Dalmas, Tengellidae Dahl, Titanoecidae Lehtinen, Zorocratidae Dahl and Zoropsidae Bertkau, which were suggested as related to Macrobuninae by previous studies. Our main results confirm Macrobuninae as not forming a monophyletic group with Amaurobiidae and shows the need to erect Macrobunidae Petrunkevitch, 1928 new rank to include Macrobuninae and relatives. Three other subfamilies are proposed here: Retirinae subfam. nov., Pakehinae subfam. nov., and Zanomyinae Ubick, 2005 new rank. Chummidae, currently composed by one genus and two species, is considered a junior-synonym with Macrobunidae. Amaurobiidae appears as sister group of the \"Oval Calamistrum Clade\" and the \"Fused Paracribellar clade\". The subfamily Macrobuninae is revised at the generic-level and redelimited to include a total of 26 genera. Of those, thirteen are newly described: Siyabonga gen. nov., Peckmaria gen. nov., Ijoubetumsam gen. nov., Imbumbulu gen. nov., Ibhulashi gen. nov., Umunwe gen. nov., Pigozzoi gen. nov., Samadhia gen. nov., Naynay gen. nov., Segoko gen. nov., Deusemais gen. nov., Madiba gen. nov. and Ushaka gen nov.. The remaining known genera are redescribed including their type-species, except the ones with recent, up to date descriptions. Seventeen new species are described: Emmenomma joshuabelli sp. nov., Macrobunus alejandrosanzi, sp. nov., Macrobunus eniomattosi sp. nov., Yupanquia lenktaitisi sp. nov., Ijoubetumsam frizzellae sp. nov., Deusemais viximaria sp. nov., Naynay meikleae sp. nov., Pigozzoi pifozonho sp. nov., Samadhia kellyfujiharae sp. nov., Siyabonga kakhulu sp. nov., Imbumbulu westhuizenis sp. nov., Madiba haddadi sp. nov., Ushaka umsila sp. nov., Ushaka philai sp. nov., Ibhulashi lakeside sp. nov., Umunwe ndabae sp. nov. and Segoko chueneorum sp. nov. Eight genera removed from Macrobuninae are assigned to other subfamilies and/or families. All taxonomic changes are justified by the phylogenetic analysis. For the first time the male specimens of Hicanodon Tullgren, Yupanquia Lehtinen and Chresiona Simon are described; Anisacate fuegianum bransfield Usher is raised to the species level, A. bransfield Usher new rank; Emmenomma beauchenicum Usher is considered junior synonym of E. oculatum Simon; Emmenomma oculatum obscurum Simon is removed from the synonym with E. oculatum and raised to the species level, Emmenomma obscurum Simon new rank. The type specimens of Macrobunus backhauseni (Simon) are considered non co-specifics and a new species Macrobunus alejandrosanzi sp. nov. is described based on the female. The true female of M. backhauseni is described for the first time. Other taxonomic changes include: removal of Notolathys Mello-Leitão from synonymy with Auximella Strand and placement as a junior synonym of Retiro Mello-Leitão; to consider Urepus Roth a junior synonym of Auximella; and Tymbira Mello-Leitão a junior synonym of Metaltella Mello-Leitão / Macrobuninae é alvo de uma revisão e análise cladística. Esta subfamília, que já foi considerada a maior de Amaurobiidae, mostra-se pouco relacionada aos Amaurobiinae ou \"amaurobiideos verdadeiros\". A matriz deste estudo, composta por 82 taxa terminais e 107 caracteres inclui representantes de todos os gêneros de Macrobuninae e novos taxa desta subfamília. Como grupo-externo, foram utilizados representantes de: Agelenidae Koch, Amaurobiidae, Amphinectidae Forster & Wilton, Chummidae Jocqué, Desidae Pocock, Dictynidae O. P.-Cambridge, Phyxelididae Lehtinen, Stiphidiidae Dalmas, Tengellidae Dahl, Titanoecidae Lehtinen, Zorocratidae Dahl e Zoropsidae Bertkau, uma vez que estas famílias foram relacionadas a Macrobuninae em outros estudos. Os resultados principais confirmam que Macrobuninae não está intimamente relacionada a Amaurobiidae e confirma a necessidade de elevar Macrobuninae à categoria de família, Macrobunidae Petrunckevitch, 1928 status nov. a fim de incluir os Macrobuninae e generos relacionados. Três subfamílias aqui descritas: Retirinae subfam. nov., Pakehinae subfam. nov., and Zanomyinae Ubick, 2005 status nov.. Chummidae Jocqué, atualmente composta por um gênero e duas espécies, passa a ser considerada sinônimo-junior de Macrobunidae. Amaurobiidae aparece como grupo-irmão dos clados \"paracribellares fundidas\" e calamistro oval. A subfamília Macrobuninae é revisada em nível genérico e redelimitada a fim de incluir um total de 26 gêneros. Destes, treze gêneros novos são descritos: Siyabonga gen . nov., Peckmaria gen. nov., Ijoubetumsam gen. nov., Imbumbulu gen. nov., Ibhulashi gen. nov., Umunwe gen. nov., Pigozzoi gen. nov., Samadhia gen. nov., Naynay gen. nov., Segoko gen. nov., Deusemais gen. nov., Madiba gen. nov. and Ushaka gen nov.. Dos treze gêneros conhecidos, apenas os que possuem descriçoões recentes e atualizadas não tiveram suas espécies-tipo redescritas. Dezessete espécies novas são descritas: Emmenomma joshuabelli sp. nov., Macrobunus alejandrosanzi, sp. nov., Macrobunus eniomattosi sp. nov., Yupanquia lenktaitisi sp. nov., Ijoubetumsam frizzellae sp. nov., Deusemais viximaria sp. nov., Naynay meikleae sp. nov., Pigozzoi pifozonho sp. nov., Samadhia kellyfujiharae sp. nov., Siyabonga kakhulu sp. nov., Imbumbulu westhuizenis sp. nov., Madiba haddadi sp. nov., Ushaka umsila sp. nov., Ushaka philai sp. nov., Ibhulashi lakeside sp. nov., Umunwe ndabae sp. nov. e Segoko chueneorum sp. nov.. Oito gêneros são removidos de Macrobuninae e transferidos para outras subfamílias e/ou famílias. As mudanças taxonômicas apresentadas são corroboradas pela análise cladística. São apresentadas as primeiras descrições de machos de espécies de Hicanodon Tullgren, Yupanquia Lehtinen e Chresiona Simon. Anisacate fuegianum bransfield Usher é elevada a categoria de espécie, A. bransfield Usher stat. nov.. Emmenomma beauchenicum Usher é considerada sinônimo junior de E. oculatum. Emmenomma oculatum obscurum Simon é removida da sinonímia e elevada a categoria de espécie, Emmenomma obscurum Simon stat. nov.. Os espécimes-tipo de M. backhauseni são aqui considerados duas espécies diferentes e com base na fêmea uma espécie nova M. alejandrosanzi sp. nov. é descrita. A verdadeira fêmea de M. backhauseni (Simon) é descrita pela primeira vez. Outras mudanças taxonômicas proveniente do estudo dos espécimes-tipo incluem remover Notolathys Mello-Leitão da sinonímia com Auximella Strand e transferir Notolathys para sinônimo-junior de Retiro Mello-Leitão; sinonimizar Urepus Roth e Auximella; considerar Tymbira Mello-Leitão sinônimo-junior de Metaltella Mello-Leitão

The cranial morphology of fossil and living sea turtles (Cheloniidae, Dermochelyidae and Desmarochelyidae)

Smith, Donald Thomas Jeremy January 1989 (has links)
Many of the early taxonomic studies of fossil sea turtles relied heavily on postcranial evidence. Both the Cheloniidae and Dermochelyidae were erected on detail of the shell and limbs. ‘Desmatochelys’ was originally described in part using cranial evidence, but later workers (Zangerl and Sloan, 1960) suppressed the family on evidence from the shell. Little in the way of comparative work has been undertaken using the cranial morphology of fossil or living forms. This is thought long overdue. The first bone by bone description of the living cheloniids has revealed a large number of taxonomically useful characters and a close relationship between the genera. However, a great deal of interspecific variation was noted. ‘Chelonia mydas’ is considered to format least three subspecies on cranial evidence. The newly described ‘Natator (Chelonia) depressa’ is thought distinct from other living forms. The Dermochelyidae are seen to be a very conservative group and a large number of cranial characters link fossil and living forms. The arterial circulation of Dermochelys is redescribed and the importance of the blood flow to the head for use by the salt secreting glands in electrolyte balance is shown to be important. The Desmatochelyidae is shown to be a family in its own right, and a number of other genera, notably ‘Rhinochelys’ and ‘Notochelone’, are thought members of the group. Many of the basicranial features identified by Gaffney in the 70s for other fossil groups have been shown to be of use in the taxonomic study of the families under review.

Systematic studies in the Boea group

Puglisi, Carmen January 2014 (has links)
Since it was first published, many additional species have been ascribed to the genus Boea Comm. ex Lam. As the genus grew in size, it also grew in morphological diversity until it was recircumscribed and became the source of a number of new segregate genera. Today, the Boea group (i.e. Boea, the segregate genera and other close relatives) comprises over 200 species in some 15 genera, found from China to Australia and throughout Malesia from Sumatra to the Solomon Islands. Previous molecular studies suggested a much more complex structure to the clade than previously thought. Here the most up to date phylogeny, covering all the genera known to belong to the Boea group, is presented. Parsimony and Bayesian Inference were the chosen approaches to the phylogenetic analysis of nine matrices generated using DNA data from 277 accessions. The markers used were the nuclear ITS and the chloroplast regions trnL-trnF (intron and spacer) and ndhF-rpl32-trnLUAG. The results show important discrepancies between the current taxonomy of the group and the clades delineated by the phylogeny. In an attempt to establish a natural classification of Boea and its allies, taxonomic and nomenclatural work was carried out on most of the genera found to be non-monophyletic. Boea Comm. ex Lam. is divided into two genera. The recircumscribed Boea is restricted to the group of taxa found in New Guinea, Solomon Islands and Australia. The genus is fully revised and contains 11 species, including the newly described Boea morobensis C.Puglisi. The Southeast Asian group of species formerly attributed to Boea, centred in Thailand, is given the resurrected name Dorcoceras Bunge. To the four species traditionally known to belong to this group, three new ones are added. These are Dorcoceras brunneum C.Puglisi, D. glabrum C.Puglisi and D. petiolatum C.Puglisi. Damrongia is deeply transformed with the synonymisation of D. cyanantha Triboun in D. trisepala (Barnett) D.J.Middleton & A.Weber, and the inclusion of Boea clarkeana Hemsl. and the three Asian species of Streptocarpus Lindl., S. orientalis Craib, S. burmanicus Craib and S. sumatranus B.L.Burtt. As a result of the phylogenetic study, a new genus, Middletonia C.Puglisi, is segregated from Paraboea. Middletonia consists of five species, including the newly described Middletonia glebosa C.Puglisi, and has its centre of distribution in Thailand. Finally, Paraboea (C.B.Clarke) Ridl. is recircumscribed with the inclusion of the genera Trisepalum C.B.Clarke and Phylloboea Benth. In order to limit the number of new combinations needed and maintain clarity, the name Paraboea was conserved against both Phylloboea and Trisepalum. In addition to the 15 new combinations in Paraboea, a new species from the Philippines, P. zamboangana C.Puglisi, is described.

Taxonomy and Pharmacognostic studies of Tarchonanthus camphoratus species complex (Tarchonanthea, Asteraceae)

Aro, Abimbola January 2010 (has links)
Thesis (Msc.(Pharmacology))--University of Limpopo, 2010. / Taxonomy and Pharmacognostic studies of Tarchonanthus camphoratus species complex (Tarchonanthea, Asteraceae) The genus Tarchonanthus belongs to the family Asteraceae, the subfamily Cichorioideae and the tribe Tarchonantheae. Tarchonanthus is one of the few Astareceae genera that includes a tree. Furthermore, it is dioecious, with male and female flowers produced on different plants. The specific name is usually chosen to indicate some striking characteristics of the plant. The name camphoratus refers to the strong smell of camphor given off when the leaves are crushed. Various parts of Tarchonanthus species are used medicinally. Infusions and tinctures of the leaves and twigs are used for stomach trouble, abdominal pain, headache, toothache, asthma, bronchitis and inflammation. The main aim of this study was to improve the overall knowledge available on Tarchonanthus camphoratus and T. parvicapitulatus by resolving the uncertainties surrounding the taxonomy and also to check for the toxicity and the therapeutic effect of this plant. A micromorphological and solubility studies proved useful in distinguishing between T. camphoratus and T. parvicapitulatus since the macromorphological characteristics of the plant did not prove useful due to overlapping keys used to distinguish the two species. A solubility studies also proved useful in differentiating between male, female or sterile plants of T. camphoratus and T. parvicapitulatus. The results that were obtained from the TLC plates showed that there are differences in the chemical composition of the acetone extracts of T. camphoratus and T. parvicapitulatus. Moreso, this study showed that the acetone extract of T. parvicapitulatus has more antioxidant properties than T. camphoratus. The therapeutic study also revealed that the plant extract from the leaves of T. camphoratus and T. parvicapitulatus showed no prophylactic protection against smooth muscle contraction of guinea-pig treachea but the plant extract of T. parvicapitulatus could relax pre-existing smooth muscle contraction of guinea-pig trachea. Superoxide production was significantly inhibited by both T. parvicapitulatus and T. camphoratus plant extract, but the rate of superoxide inhibition of T. parvicapitulatus extract were more prominent than it was for T. camphoratus extract. The inhibitory effects of the water extract of T. camphoratus and T. parvicapitulatus on the isolated human neutrophils could be due to the activity of the intermediate polar compounds which include flavonoids. This explains why these plant extracts are used by traditional healers for the relieve of ailments such as abdominal pain, headache, toothache T. parvicapitulatus are toxic but the plant extracts of T. camphoratus did not show significant toxicity to isolated human neutrophils. This study has helped to improve the overall knowledge available on Tarchonanthus camphoratus and Tarchonanthus parvicapitulatus by using different pharmacognostic tools to resolve the uncertainties surrounding the taxonomy and to determine the toxicity and the therapeutic effects of this plant.

Systematics of Elatostema (Urticaceae)

Hadiah, Julisasi Tri, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW January 2007 (has links)
Elatostema J.R.Forst. & G.Forst. (Urticaceae) is a taxonomically problematic genus of approximately 300 species that is widespread throughout the tropical, subtropical and sub-temperate regions of Africa through to SE Asia, Australasia to Polynesia. Morphological and molecular analyses were conducted to evaluate the infra-familial classification of the Urticaceae, to test the monophyly of Tribe Elatostemeae, to define generic limits of Elatostema and assess its relationship within the tribe, and to examine the current infrageneric grouping within Elatostema. Phylogenetic analyses based on choloroplast DNA sequences of rbcL and trnL-F do not provide support for the monophyly of Urticaceae, because of the position of Poikilospermum (currently Cecropiaceae) within the tribe Urticeae. Although the status of Cecropiaceae is equivocal, there is support for the inclusion of this family in the Urticaceae, with Cecropia and Coussapoa (Cecropiaceae) having close affinities to the Boehmerieae and Parietarieae. The phylogenetic position of Myriocarpa is unresolved, but is excluded from the Boehmerieae, as currently classified. The Elatostemeae is paraphyletic with Pilea placed sister to the Urticeae. Evaluation of the infrageneric classification of Elatostema, based on phylogenetic analyses of both morphological and molecular data (trn and ITS) does not support the current subgeneric classification as proposed by Schr??ter and Winkler (1935, 1936). The analyses support two main infrageneric grouping: (1) a group consisting of Elatostema subg. Pellionia and Procris, and (2) a group consisting of the remaining members of Elatostema (including E. griffithianum ??? subg. Pellionia). The molecular data are regarded as a more accurate estimate of the phylogeny than provided by morphology, with molecular data having a higher Rescaled Consistency Index on the most parsimonious trees, together with a much greater level of resolution and support than that of the morphological analyses.

The systematics and biology of the genus Poltys (Araneae: Araneidae) in Australasia

Smith, Helen Motum January 2006 (has links)
Doctor of Philosophy / The genus Poltys C.L. Koch is revised for Australia and partly examined for the wider Australasian region. Five of the ten species originally described from Australia are found to be synonymous with South East Asian species, a further three are synonymous with an Australian species and four which were previously overlooked are newly described, resulting in a total of eight current species recorded from Australia. Poltys coronatus Keyserling, P. keyserlingi Keyserling, P. multituberculatus Rainbow and P. penicillatus Rainbow are synonymised with P. illepidus C.L. Koch; P. microtuberculatus Rainbow is synonymised with P. stygius Thorell; P. bimaculatus Keyserling, P. mammeatus Keyserling and P. salebrosus Rainbow are synonymised with P. laciniosus Keyserling; P. sigillatus Chrysanthus from New Guinea is synonymised with P. frenchi Hogg. Five new species are described, four from Australia, P. grayi sp.nov., P. jujorum sp.nov., P. milledgei sp.nov. and P. noblei sp.nov., and P. timmeh sp.nov. from New Caledonia. A checklist of all Poltys types described from the region, including illustrations, is included. The delimitation of the Australian species is aided and confirmed by DNA sequencing. Sequences from two genes and morphological characters are used to reconstruct a phylogeny of the Australian species. The generic relationships of Poltys are examined in the context of the putative tribe Poltyini (Simon, 1895). No firm conclusions about the relationships of Poltys can be made, however the results indicate that the Poltyini is polyphyletic. The results of field studies are presented; these indicate that P. noblei is less likely to move between web sites than diurnal taxa referenced from other studies. Specimens were shown to sometimes occupy the same, or a closely adjacent web site, for over eight months. Spiders most often move during spring and summer but often remain in the same site throughout winter. Specimens of Poltys noblei are also shown to be unevenly distributed on trees and bushes in respect to aspect and position. It is suggested that these observations indicate the importance of camouflage to deter wasp and bird predators. Specimens of several Poltys species were reared from egg sacs, confirming male–female identification and showing the variation in abdominal shape between siblings. Growth data indicate that sibling males and females cannot normally interbreed; males mature after 2–4 moults, females after 8–11 moults. Field and cage observations of general aspects of Poltys biology are presented including preferred habitat, prey capture and handling, courtship and mating, competition and web construction.

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