The influence of investigator disturbance on aggressive behaviour and breeding success of ring-billed gulls (Larus delawarensis) /

Increased losses of eggs and chicks resulting from human intrusion (investigator or other) into seabird colonies has been well documented. In 1990/91, I studied the effects of investigator disturbance on aggressive behaviour and breeding success of individual pairs of ring-billed gulls nesting at two colonies near Port Colborne, Ontario. The insular colony was on an artificial breakwall, associated with the Welland Ship Canal, approximately 1 km off the north shore of Lake Erie. The mainland colony was adjacent to the canal approximately 1 km east of the breakwall. The frequencies of adult threat and assault behaviours, chick movement and adult attacks on chicks were recorded by continuous scan sampling 30 min prior to, 30 min during and 60 (2 X 30) min after investigator disturbance. The frequency of threat and assault behaviours increased during the period of investigator activity in the colony while the duration of wingpulls and beakpulls decreased. Significantly more chicks ran ("runners") from their natal territories during disturbances and "runners" were more frequently attacked than "territorial" chicks. No chicks were fatally attacked during disturbance and "runners" returned to their natal territories quickly after disturbance. Breeding success was determined for pairs nesting in study plots subjected to two levels of disturbance (normal and moderate). The disturbance level of each plot differed in visitation frequency and activities performed on each visit. Investigator disturbance had no effect on the hatching success or fledging success (taken as 21 days of age) of ring-billed gull study pairs at either colony.

Broad reduction and adoption in ring-billed gulls (Larus Delaworensis): the potential for inergenerational conflict

Patterns of intra-clutch egg size variation and intra-clutch hatch intervals in the Ring-billed gull (Larus delawarensis) were documented during the peak nesting period of two consecutive breeding seasons, at a colony near Port Colborne, Ontario. Egg size decreased with laying order; third laid eggs were significantly smaller than first laid eggs. Hatching of the third egg was delayed from that of first and second eggs. Intraclutch egg size differences established initial size disparities among chicks at hatch. Hatch intervals further exaggerated size disparities during the early post brood completion period. Competitive asymmetries among chicks were associated with increased mortality rates among third hatched chicks despite the lack of evidence of a sibling feeding hierarchy. Fledging success in 1987 was greater than in 1988. A "brood reduction strategy" appears to have enabled parents in 1987, to obtain an extra unit of reproductive fitness, while in 1988 parents were often unable to raise the entire brood and third chicks likely represented insurance reproductive value. Experimental broods (1988) were created in which hatch intervals were double those of natural intervals. The size disparities among chicks were significantly greater than in control broods, and the pattern of mortality among chicks suggested that first chicks benefited at a cost to second and third chicks. Parents of peak experimental broods achieved a fledging success rate similar to that of control broods. Characteristics of chick adoptions were also recorded. In each study year, 9 chicks abandoned their natal territories, 6 of which were adopted. Chicks consistently established themselves into broods where they were older than resident chicks. No direct evidence of cost to foster parents, or benefits to adopted chicks was obtained, although fledging success of adopted chicks was high.

Seasonal variation in the reproductive biology of the ring -billed gull (Larus delawarensis)

The reproductive biology of the Ring-billed Gull (Larus delawarensis) was studied on Gull Island, Presqu'ile Provincial Park, Ontario, in 1976 and 1977. Early started clutches (comprising the majority of clutches on Gull Island) in 1977 produced more chicks per nest (2.20 ± 0.09) than late started clutches (0.86 ± 0.13) as a result of reductions in mean clutch size, hatching success and fledging success with date of clutch initiation. Seasonal changes in mean clutch size, hatching success and fledging success also resulted in early clutches, initiated at the peak of clutch starts, producing more chicks per nest (2.34 ± 0.11) than either pre-peak (2.13 ± 0.20) or post-peak (1.82 ± 0.29) clutches. Possible reasons for these trends, including the observed predominance of immature plumaged, breeding gulls in late started areas, are discussed. Clutches were deserted at night for varying lengths of time from at least 15 April until 10 May, 1977. It is suggested that this nocturnal desertion behaviour resulted in the enhancement of inter- and intra-clutch hatching synchrony in early started areas and further, that this may in part explain the existence of the behaviour in terms of its adaptive significance.

Seasonal variation in hatching pattern and chick survival in the ring-billed gull Larus delawarensis

The general objective of my study was to monitor proximate causes and seasonal patterns of hatching asynchrony and chick survival in the Ring-billed Gull (Larus delawarensis). Two different plots were set up at a Ring-billed Gull colony near Port Colborne, Ontario in the summer of 1992. One group was from 'peak' nesting pairs (clutches initiated between 15 April and 1 May); a second group was from 'late' nesting pairs (clutches initiated between 9 .. 22 May). Despite equal intra-clutch egg laying intervals between the peak and late periods, intra-clutch hatching intervals lengthened as the season progressed (ie. hatching became more asynchronous). Clutches from both periods were monitored for nocturnal attendance and brood patch development of parents was monitored during the egg laying period. Late nesters were characterized by an absence of nocturnal desertion, substantial brood patch defeatheration at clutch initiation and a reduction in the number of chicks fledged per pair. Chick survival to 25 days (taken as fledging) reflected patterns of chick mass at brood completion and five days post-brood completion, in peak clutches. In late clutches, survival was poor for all chicks and, was partially independent of hatching order, due in part to stochastic events such as Herring Gull predation and adverse weather. In both the peak and late periods, last-hatched C-chicks realized the poorest survival to fledging among brood mates. An artificial hatching pattern (manipulated synchrony) and an artificial hatching order were created, in three-chick broods, through a series of egg exchanges. In peak and late clutches manipulated to hatch synchronously (s; 24 h): C-chick survival to fledging did not differ from the survival of A- and B-chicks, in the peak period. In the late period, the survival of C-chicks was significantly lower than that of A-chicks. In peak clutches manipulated such that chicks from last-laid eggs (C-chicks) hatched 24 h - 48 h ahead of the A- and B- chicks, C-chick survival was greater than in controls. Within those broods, C-chicks survived better on average than both A- and B- chicks.

The application of the structural correlation method to determine the reaction coordinate for a putative ring closure reaction

The cr ystal structure of the compound 2-benzoylethylidene-3-(2,4- dibromophenyl)-2,3-dihydro-5-phenyl-l,3,4-thiadiazole* C23H16Br2NZOS (BRMEO) has been determined by using three dimensiona l x-ray diffraction data. The crys tal form is monoclinic, space group P21/c, a = 17.492(4), o -.t' 0 R 0 b =: 16.979(1), c = 14.962(1) A, "X. =o= 90 ',= 106.46(1) , z = 8, graphite-monochromatized Mo~ rad iation, Jl= 0.710J3~, D = 1.62g/cc and o D = 1.65g/cc. The data were col lected on ~ Nonius CAD-4 c diffractometer. The following atoms were made anisotropic: Br, S, N, 0, C7, and C14-C16 for each i ndependent molecu le ; the rest were left isotropic. For 3112 independent refl ec tions with F > 6G\F), R == 0.057. The compound has two independent molecules within the asymmetric unit. Two different conformers were observed which pack well together. /l The S---O interaction distances of 2.493(6) and 2 . 478(7) A were observed for molecules A and B respectively. These values are consistent with earlier findings for 2-benzoylmethylene-3-(2,4-dibromophenyl)- ~~ 2,3-dihydro-5-phenyl-l,3,4-thiadiazole C22H14Br2N20S (BRPHO) and 2-benzoylpropylidene-3-(2,4-dibromophenyl)-2,3-dihydroiii ,'r 5-phenyl-l,3,4-thiadiazole C24H18Br2N20S (BRPETO ) where S---O distances are l ess than the van der Waals (3.251\) but greater than those expected for () a single bond (1.50A). From the results and the literature it appears obvious that the energy/reaction coordinate pathway has a minimum between the end structures (the mono- and bicyclic compounds). * See reference (21) for nomenclature.

Explorations of Intramolecular [5+2] Cycloadditions of Ring-Constrained Vinylcyclopropanes

The first example of a [5+2] cycloaddition reaction wherein the olefin of the vinylcyclopropyl moiety is constrained in a carbocycle was explored, and possible reasons on the lack of reactivity of the substrate were studied. A simple model substrate was synthesized and subjected to cycloaddition conditions to determine if the reason for the lack of reactivity was related to the complexity of the substrate, or if the lack of “conjugative character” of the cyclopropyl ring with respect to the olefin is responsible. A more complex bicyclic substrate possessing an angular methyl group at the ring junction was also synthesized and explored, with evidence supporting the current theory of deconjugation of the cyclopropyl moiety.

Ring-opening of cycloalkane epoxides and aziridines with aromatic amines : toward the total synthesis of pactamycin

Résumé Cette thèse consiste en trois thèmes résumés dans les paragraphes ci-dessous. L’influence de différents groupements protecteurs du groupe hydroxyle lors des réactions d’ouverture des cis- et trans- 3-hydroxy-1,2-époxycycloalcanes a été étudiée. Il a été montré que Yb(OTf)3 constituait un catalyseur doux pour l’ouverture régiosélective de cycles afin d’obtenir les -anilino cycloalcanols correspondants avec de bons rendements. Le chauffage du milieu réactionnel dans le toluène comme solvant a permis d’augmenter la cinétique de la réaction, au dépend du rendement. La partie aniline a été régiosélectivement introduite en position vicinale du groupe hydroxyle ou éther afin d’obtenir un unique régioisomère. La même tendance a été observée avec les époxydes du 3-azidocyclohex-1-ène et du 3-carbamate correspondant. Le temps de réaction a été réduit lorsque Yb(OTf)3 a été dissous dans l’acétonitrile. Le triflate d’ytterbium (III) a également été utilisé comme catalyseur pour l’ouverture de cycle régiosélective d’aziridines non-activées sur des cyclohexanes portant des substituants azotures ou éthers de benzyle. L’ion azoture ou l’aniline forment les produits trans correspondants, donnant alors accès à des diamines vicinales avec de bons rendements. Un éther ω-alcoxy p-méthoxybenzylique racémique, inhibiteur de HDAC, a été ainsi préparé en huit étapes synthétiques (rendement total de 26%) à partir du 1-((tert-butyldiphénylsilyl)oxy)hept-6-èn-2-ol. Ceci représente un progrès par rapport à la précédente méthode (9 étapes, rendement total de 16%). La métathèse croisée se montre particulièrement efficace et pratique dans cette stratégie et l’alkylation par le trichloroacétimidate de p-méthoxybenzyle en présence de Sc(OTf)3 améliore le rendement global de la synthèse. Un aminoalcool présent dans la pactamycine et contenant le squelette carboné, les groupements fonctionnels et la stéréochimie requise a été synthétisé en 27 étapes à partir de la L-thréonine. La méthodologie décrite dans cette thèse permet la synthèse de cet intermédiaire clé à l’échelle multigramme.

Enantiopure 3-substituted piperidines via an aziridinium ion ring expansion

Ce mémoire décrit le développement d’une nouvelle méthodologie d’expansion de cycle irréversible à partir de N-alkyl-3,4-déhydroprolinols pour former des N-alkyl tétrahydropyridines 3-substituées en passant par un intermédiaire aziridinium bicyclique. Cette méthode permet l’introduction d’un vaste éventail de substituants à la position 3 et tolère bien la présence de groupements aux positions 2 et 6, donnant accès à des pipéridines mono-, di- ou trisubstituées avec un excellent diastéréocontrôle. De plus, il est démontré que l’information stéréogénique du 3,4-déhydroprolinol de départ est totalement transférée vers le produit tétrahydropyridine. Additionnellement, une méthodologie fut dévelopée pour la préparation des produits de départ 3,4-déhydroprolinols en forme énantiopure, avec ou sans substituants aux positions 2 et 5, avec un très bon stéréocontrôle. Le premier chapitre présente un résumé de la littérature sur le sujet, incluant un bref survol des méthodes existantes pour la synthèse de pipéridines 3-substituées, ainsi qu’une vue d’ensemble de la chimie des aziridiniums. L’hypothèse originale ainsi que le raisonnement pour l’entreprise de ce projet y sont également inclus. Le second chapitre traite de la synthèse des N-alkyl-3,4-déhydroprolinols utilisés comme produits de départ pour l’expansion de cycle vers les tétrahydropyridines 3-substituées, incluant deux routes synthétiques différentes pour leur formation. Le premier chemin synthétique utilise la L-trans-4-hydroxyproline comme produit de départ, tandis que le deuxième est basé sur une modification de la réaction de Petasis-Mannich suivie par une métathèse de fermeture de cycle, facilitant l’accès aux précurseurs pour l’expansion de cycle. Le troisième chapitre présente une preuve de concept de la viabilité du projet ainsi que l’optimisation des conditions réactionnelles pour l’expansion de cycle. De plus, il y est démontré que l’information stéréogénique des produits de départs est transférée vers les produits. iv Au quatrième chapitre, l’étendue des composés pouvant être synthétisés par cette méthodologie est présentée, ainsi qu’une hypothèse mécanistique expliquant les stéréochimies relatives observées. Une synthèse énantiosélective efficace et divergente de tétrahydropyridines 2,3-disubstituées est également documentée, où les deux substituants furent introduits à partir d’un intermédiaire commun en 3 étapes.

Synthesis of ring A of (+)-Ambruticin S and bicyclic nucleosides for antisense drug technology

La synthèse énantiosélective de la (+)-ambruticine S, un produit naturel antifongique a été effectuée au sein de notre groupe. Trois approches ont été développées pour la synthèse du fragment lactone (cycle A). Ces trois voies d’accès au cycle A ont pour intermédiaire commun le methyl α-D-glycopyranoside déjà porteur du diol requis et disponible commercialement à bon prix. Une désoxygénation de l’hydroxyle en C-4 et l’homologation d’un carbone de la chaine latérale en C-6 ont permis l’obtention du cycle lactonique A. Le deuxième projet est une collaboration entre le groupe Hanessian et ISIS Pharmaceuticals afin de développer de nouveaux oligonucléosides antisens. Les nucléosides antisens [4.3.0]-bicycliques cis et trans ont été synthétisés avec succès à partir d’un monosaccharide naturel commun, L-arabinose, porteur des stéréocentres requis. Un réaction clé d’allylation de Sakurai a permis d’obtenir les diastéréoisomères cis et trans dans des conditions de contrôle de type Felkin-Ahn et de contrôle par chélation respectivement. Les composés bicycliques finaux cibles ont été obtenus par une réaction d’aldol intramoléculaire catalyzéé par la proline, par métathèse de fermeture de cycle et par l’application de la méthode de Vorbrüggen pour la synthèse de nucléosides.

Nucleophilic ring-opening of Methyl 1- Nitrocyclopropanecarboxylates

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Comparison of Electromagnetic Band Gap and Split-Ring Resonator Microstrip Lines as Stop Band Structures

In this paper, microstrip lines magnetically coupled to splitring resonators (SRRs) are conquved to electromagnetic bundgup (EBG) nr,rrostrip lines in terns q/ their stop-heard penjbrnmrnce and dimensions. In bath types o/ trunsmis•siou lines, signal propagation is inhibited in it certain jequency bwuL For EBG microstrip lines, the central frequency of such a forbidden band is determined by the period of the structure, whereas in SRR-hased microstrip lines the position of the frequency gap depends on the quasi-static resonant frequency of the rings. The main relevant conrributiun of this paper is to provide a tuning procedure to control the gap width in SRR microstrip lines, and to show that by using SRRs, device dimensions ale much smaller than those required by EBGs in order to obtain similar stop-banal performance. This has been demonstrated by fill-wave electromagnetic simulations and experimentally verified from the characterization ql two fabricated microstrip lines: one with rectangular SRRs etched on the upper substrate side, and the other with a periodic perturbation cf'strip width. For similar rejection and 1-(;H,. gap width centered at 4.5 Gllz, it has been found that the SRR microstrip line is•,fve times shorter. In addition, no ripple is appreciable in the allowed band for the .SRR-hared structure, whereas due to dispersion, certain mismatch is expected in the EBG prototype. Due to the high-frequency selectivity, controllable gap width, and small dimensions, it is believed that SRR coupled to planar transmission lines can have an actual impact on the design of stop-band filters compatible with planar technology, and can be an alternative to present solutions based on distributed approaches or EBG

Defect analysis of semiconductor thin films for photovoltaic applications using photo-luminescence and photo-conductivity

The present thesis can be divided into three areas:1) the fabrication of a low temperature photo-luminescence and photoconductivity measuring unit 2) photo-luminescence in the chalcopyrite CulnSez and CulnS2 system for defect and composition analysis and 3) photo-luminescence and photo-conductivity of In:JS3. This thesis shows that photo-luminescence is one of most essential semiconductor characterization tool for a scientific group working on photovoltaics. Tools which can be robust, non-destructive, requiring minimal sample preparation for analysis and most informative of the device applications are sought after by industries and this thesis is towards establishing photo-luminescence as "THE" tool for semiconductor characterization. The possible application of photo-luminescence as a tool for compositional and quality analysis of semiconductor thin films has been worked upon by this thesis. Photo-conductivity complement photo-luminescence and together they provide all the information required for the fabrication of an opto-electronic device.

Strange attractors in the Saturn ring system

The theory of deterministic chaos is used to study the three rings A, B, and C of Saturn and the French and Cassini divisions in between them. The data set comprises Voyager photopolarimeter measurements. The existence of spatially distributed strange attractors is shown, implying that the system is open, dissipative, nonequilibrium, and non-Markovian in character.

Transition Metal Complexes with Ring Incorporated Thiosemicarbazones: Syntheses,Structures and Spectral Properties

In the present work,the chelating behaviour of thiosemicarbazones of a heterocyclic diketone, 2,6-diacetylpyridine is studied,with the aim of investigating the influence coordination exerts on their conformation and /or configuration, in connection with the nature of the metal and of the counter ion.The various possibilities like unsubstitution,ring incorporation at terminal nitrogen and condensation of one of the ketone group alone have been tried for ligand selection.Mainly first row transition metals like manganese,iron,nickel,copper,zinc and cadmium are studied.Metals like cobalt also were studied but could not result in fruitful isolation of the compound due to solubility problems.Different spectroscopic and characterization techniques have been utilized to reveal the nature of the metal and the ligands in coordinated metal complex.