27 resultados para Harvard University.--Hollis Professorship of Mathematicks and Natural Philosophy.

em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast


Relevância:

100.00% 100.00%

Publicador:

Resumo:

A simple, new method permitting the simultaneous determination and confirmation of trace residues of 24 different growth promoters and metabolites using liquid chromatography-mass spectrometry was developed and validated. The compounds were extracted from bovine tissue using acetonitrile; sodium sulphate was also added at this stage to aid with purification. The resulting mixture was then evaporated to approximately 1 ml and subsequently centrifuged at high speed and an aliquot injected onto the LC-MS/MS system. The calculated CC values ranged between 0.11 and 0.46 mu g kg-1; calculated CC were in the range 0.19-0.79 mu g kg-1. Accuracy, measurement of uncertainty, repeatability and linearity were also determined for each analyte. The analytical method was applied to a number of bovine tissue samples imported into Ireland from third countries. Levels of progesterone were found in a number of samples at concentrations ranging between 0.28 and 30.30 mu g kg-1. Levels of alpha- and beta-testosterone were also found in a number of samples at concentrations ranging between 0.22 and 8.63 mu g kg-1 and between 0.16 and 2.08 mu g kg-1 respectively.

Relevância:

100.00% 100.00%

Publicador:

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The lifetime success and performance characteristics of communally reared offspring of wild native Burrishoole (native), ranched native (ranched) and non-native (non-native) Atlantic salmon Salmo salar from the adjacent Owenmore River were compared. Non-native year parr showed a substantial downstream migration, which was not shown by native and ranched parr. This appears to have been an active migration rather than competitive displacement and may reflect an adaptation to environmental or physiographic conditions within the Owenmore River catchment where the main nursery habitat is downstream of the spawning area. There were no differences between native and ranched in smolt output or adult return. Both of these measures, however, were significantly lower for the non-native group. A greater proportion of the non-native Atlantic salmon was taken in the coastal drift nets compared to the return to the Burrishoole system, probably as a result of the greater size of the non-native fish. The overall lifetime success of the non-native group, from fertilized egg to returning adult, was some 35% of native and ranched. The ranched group showed a significantly greater male parr maturity, a greater proportion of 1+ year smolts, and differences in sex ratio and timing of freshwater entry of returning adults compared to native, which may have fitness implications under specific conditions.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A 1.2 m sediment core from Lake Forsyth, Canterbury, New Zealand, records the development of the catchment/lake system over the last 7000 years, and its response to anthropogenic disturbance following European settlement c. 1840 AD. Pollen was used to reconstruct catchment vegetation history, while foraminifera, chironomids, Trichoptera, and the abundance of Pediastrum simplex colonies were used to infer past environmental conditions within the lake. The basal 30 cm of core records the transition of the Lake Forsyth Basin from a tidal embayment to a brackish coastal lake. Timing of closure of the lake mouth could not be accurately determined, but it appears that Lake Forsyth had stabilised as a slightly brackish, oligo mesotrophic shallow lake by about 500 years BP. Major deforestation occurred on Banks Peninsula between 1860 AD and 1890 AD. This deforestation is marked by the rapid decline in the main canopy trees (Prumnopitys taxifolia (matai) and Podocarpus totara/hallii (totara/mountain totara), an increase in charcoal, and the appearance of grasses. At around 1895 AD, pine appears in the record while a willow (Salix spp.) appears somewhat later. Redundancy analysis (RDA) of the pollen and aquatic species data revealed a significant relationship between regional vegetation and the abundance of aquatic taxa, with the percentage if disturbance pollen explaining most (14.8%) of the constrained variation in the aquatic species data. Principle components analysis (PCA) of aquatic species data revealed that the most significant period of rapid biological change in the lakes history corresponded to the main period of human disturbance in the catchment. Deforestation led to increased sediment and nutrient input into the lake which was accompanied by a major reduction in salinity. These changes are inferred from the appearance and proliferation of freshwater algae (Pediastrum simplex), an increase in abundance and diversity of chironomids, and the abundance of cases and remains from the larvae of the caddisfly, Oecetis unicolor. Eutrophication accompanied by increasing salinity of the lake is inferred from a significant peak and then decline of P. simplex, and a reduction in the abundance and diversity of aquatic invertebrates. The artificial opening of the lake to the Pacific Ocean, which began in the late 1800s, is the likely cause of the recent increase in salinity. An increase in salinity may have also encouraged blooms of the halotolerant and hepatotoxic cyanobacteria Nodularia spumigena.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Crombie, Leslie; Haigh, David; Jones, Raymond C. F.; Mat-Zin, A.Rasid. Dep. Chem., Univ. Nottingham, Nottingham, UK. Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999) (1993), (17), 2047-54. CODEN: JCPRB4 ISSN: 0300-922X. Journal written in English. CAN 120:164608 AN 1994:164608 CAPLUS (Copyright (C) 2009 ACS on SciFinder (R)) Abstract The alkaloid homaline I was prepd. in (?) and natural (S,S)-(-) forms. Linking of 2-azacyclooctanone units either directly or successively using 1,4-dihalogenobutanes or 1,4-dihalogenobut-2-ynes is examd. (?)-5-Methyl-4-phenyl-1,5-diazacyclooctan-2-one is first made by a 2,2'-dithiodipyridine/triphenylphosphine-mediated cyclization, and then by amination and transamidative ring expansion from N-(3-chloropropyl)-4-phenylazetidin-2-one in liq. ammonia, followed by N-methylation. Coupling through a 1,4-dihalogenobutane of either the N-methylated azalactam, or the unmethylated azalactam followed by methylation, gave homaline in (?) and meso forms. (R)-(-)-phenylglycine was converted via (S)-?-phenyl-?-alanine into an (S)-?-lactam which was then alkylated with 1-bromo-3-chloropropane, and aminated and ring expanded in liq. ammonia. Coupling of the homochiral azalactam (2 mol) so formed with 1,4-dibromobutane, followed by N-methylation, gave (S,S)-(-)-homaline identical with the natural material.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background: Studies of cross-cultural variations in the perception of emotion have typically compared rates of recognition of static posed stimulus photographs. That research has provided evidence for universality in the recognition of a range of emotions but also for some systematic cross-cultural variation in the interpretation of emotional expression. However, questions remain about how widely such findings can be generalised to real life emotional situations. The present study provides the first evidence that the previously reported interplay between universal and cultural influences extends to ratings of natural, dynamic emotional stimuli.

Methodology/Principal Findings: Participants from Northern Ireland, Serbia, Guatemala and Peru used a computer based tool to continuously rate the strength of positive and negative emotion being displayed in twelve short video sequences by people from the United Kingdom engaged in emotional conversations. Generalized additive mixed models were developed to assess the differences in perception of emotion between countries and sexes. Our results indicate that the temporal pattern of ratings is similar across cultures for a range of emotions and social contexts. However, there are systematic differences in intensity ratings between the countries, with participants from Northern Ireland making the most extreme ratings in the majority of the clips.

Conclusions/Significance: The results indicate that there is strong agreement across cultures in the valence and patterns of ratings of natural emotional situations but that participants from different cultures show systematic variation in the intensity with which they rate emotion. Results are discussed in terms of both ‘in-group advantage’ and ‘display rules’ approaches. This study indicates that examples of natural spontaneous emotional behaviour can be used to study cross-cultural variations in the perception of emotion.