The Meaning of UML Models

The Unified Modelling Language (UML) is intended to express complex ideas in an intuitive and easily understood way. It is important because it is widely used in software engineering and other disciplines. Although an official definition document exists, there is much debate over the precise meaning of UML models. ¶ In response, the academic community have put forward many different proposals for formalising UML, but it is not at all obvious how to decide between them. Indeed, given that UML practitioners are inclined to reject formalisms as non-intuitive, it is not even obvious that the definition should be “formal” at all. Rather than searching for yet another formalisation of UML, our main aim is to determine what would constitute a good definition of UML. ¶ The first chapter sets the UML definition problem in a broad context, relating it to work in logic and the philosophy of science. ..

Bycatch Avoidance Programs in Two New England (USA) Fisheries

We conducted similar bycatch avoidance programs in two New England fisheries: yellowtail flounder bycatch in the sea scallop closed area fisheries and river herring bycatch in the Atlantic herring and mackerel fishery. These species have different behavioral properties: sea scallops are sessile; yellowtail flounder are demersal with limited but unknown range. Herring and mackerel are pelagic species with wide spatial and temporal ranges; river herring are anadromous. Management actions also differed between the two fisheries. The sea scallop closed area fisheries were limited in time and space with hard quotas for each species. The herring and mackerel fishery was limited in large scale areas by hard quotas, without quotas for river herring. Fishermen were motivated to avoid river herring by strong conservation pressure, river herring are listed as a species of concern and under review for endangered species by the U.S. agencies, which designation would effectively close the Atlantic herring fishery. In the scallop fisheries, we mapped and updated densities for target and bycatch stocks through real-time monitoring and communicated hotspots with captains at sea. In the herring and mackerel fishery we identified densities through port sampling and communicated hotspots to captains at sea. We also reported environmental factors of river herring density such as depth to captains. Percent participation exceeded 75% in each fisheries with evidence of avoidance behavior in both fisheries. Yellowtail bycatch was sharply reduced in the scallop closed area fisheries with some reduction of river herring bycatch in the herring and mackerel fisheries

Towards a readable formalisation of category theory

We formally develop category theory up to Yoneda's lemma, using Isabelle/HOL/Isar, and survey previous formalisations. By using recently added Isabelle features, we have produced a formal text that more closely approximates informal mathematics

Correlation of memory dysfunction and amyloid burden in mild cognitive impairment

1 page(s

Nicotinic receptors are not responsible for improved cognitive performance by galantamine in early Alzheimer's disease: A 2-[18F]F-A-85380 PET study

1 page(s

Amyloid burden in ageing subjects with and without cognitive decline

1 page(s

The Relationship Between Nicotinic Receptors and Cognitive Functioning in Healthy Aging: An In Vivo Positron Emission Tomography (PET) Study With 2-[F-18]Fluoro-A-85380

Extensive experimental and neuropathological evidence supports the general hypothesis that decline in the basal forebrain cholinergic system contributes significantly to age-related cognitive impairment. Postmortem studies suggest reductions in neuronal nicotinic acetylcholine receptors (nAChRs, particularly the α4β2 subtype) with aging. This study aimed to determine the distribution of α4β2-subtype nAChRs in vivo by 2-FA PET in healthy subjects (aged 21-83) and to establish whether there is an age-related decline in nAChRs. Furthermore, the relationship between PET measures of 2-FA binding and neurobehavioral measures of cognitive function was investigated. All participants were nonsmokers and underwent extensive cognitive testing and a PET scan after injection of 2-FA (200 MBq). Brain regional 2-FA binding was assessed through a simplified estimation of distribution volume (DVS). As expected, increasing age was associated with poorer cognitive performance, particularly on tasks assessing episodic memory and attentional processes. No significant age-related differences in regional nAChR DVS were found. Furthermore, no significant correlations were found between cognitive measures and nAChR DVS. These results are consistent with recent studies suggesting the stability of cholinergic markers during senescence. It is plausible that changes in α4β2 nAChRs do occur with advancing age, but are beyond detection by the clinical 2-FA PET approach adopted here. However, this approach may be appropriate for use in pathologies considered to undergo extensive nAChR loss such as Alzheimer's disease and Parkinson's disease.12 page(s

Relationship between nicotinic receptors and cognitive function in early Alzheimer's disease: A 2-[F-18]fluoro-A-85380 PET study

Neuronal nicotinic acetylcholine receptors (nAChRs) are critical for higher order cognitive processes. Post-mortem studies suggest reductions in nAChRs (particularly the α4β2 subtype) with ageing and in Alzheimer's disease (AD). This study aimed to; (1) quantify nAChR distribution in vivo with 2-[18F]fluoro-A-85380 (2-FA) in 15 early AD patients compared to 14 age-matched, healthy controls (HC) and (2) correlate nAChR distribution with cognitive performance in both groups. All participants were non-smokers and underwent cognitive testing along with a dynamic PET scan after injection of 200 MBq of 2-FA. Brain regional 2-FA binding was assessed through a simplified estimation of Distribution Volume (DVS). The AD group differed significantly from HC on all cognitive measures employed, with impairments on measures of attention, working memory, language, executive function, visuospatial ability, verbal learning and verbal memory (p < .05). Contrary to post-mortem data this study found no evidence of in vivo nAChR loss in early AD despite significant cognitive impairment. Furthermore, no correlation between nAChR and cognitive performance was found for either group. The findings of the current study suggest preservation of nAChRs early in AD supporting previous studies. It is possible that while the clinical 2-FA PET method described here may be insensitive in detecting changes in early AD, such changes may be detected in more advanced stages of the illness.9 page(s