Localisable Monads

Monads govern computational side-effects in programming semantics. A collection of monads can be combined together in a local-to-global way to handle several instances of such effects. Indexed monads and graded monads do this in a modular way. Here, instead, we start with a single monad and equip it with a fine-grained structure by using techniques from tensor topology. This provides an intrinsic theory of local computational effects without needing to know how constituent effects interact beforehand. Specifically, any monoidal category decomposes as a sheaf of local categories over a base space. We identify a notion of localisable monads which characterises when a monad decomposes as a sheaf of monads. Equivalently, localisable monads are formal monads in an appropriate presheaf 2-category, whose algebras we characterise. Three extended examples demonstrate how localisable monads can interpret the base space as locations in a computer memory, as sites in a network of interacting agents acting concurrently, and as time in stochastic processes

One hundred years of forensic sciences in Quebec: the evolution of scientific techniques since 1914

In 2014, Quebec's forensic science laboratory (Laboratoire de sciences judiciaires et de medicine légale) is celebrating its 100th anniversary. Since its foundation by Dr. Derome in 1914, scientific techniques in the various areas of forensic science have greatly evolved. Not only was the Laboratory the first forensic science institution in North America, it has been a pioneer for several analytical methods. The early days of the Laboratory as well as the specific evolution of the departments and divisions of biology, chemistry, arson and explosion, questioned documents, forensic pathology, odontology and anthropology, toxicology and administration will be reviewed here

Novel, acid-labile, hydroxydiether lipid cores in methanogenic bacteria.

Polar ether lipids extracted from 15 methanogenic bacteria, representative of seven genera, were screened by nuclear magnetic resonance and thin layer chromatography for the presence of hydroxyl groups on the C20-phytanyl moieties. Major amounts of hydroxydiether core lipid were confirmed for Methanosaeta concilii and discovered in two Methanosarcina species, Methanococcus voltae, and tentatively in several Methanobacterium species. Signals at 1.24 and 1.8-1.9 ppm in 1H NMR spectra are characteristic of Methanosaeta concilii lipids hydroxylated on carbon-3 (sn-3 chain). Related signals, which were shifted slightly, appeared in spectra of the polar lipids extracted from both Methanosarcina species. Following mild hydrolysis to remove the polar head groups, only two chromatographically distinct core lipids were found in significant amounts in Methanosarcina barkeri (and Methanosarcina mazei) consisting of 43% 2,3-di-O-phytanyl-sn-glycerol (C20,20-diether) and 57% C20,20-hydroxydiether. This latter core lipid differed from the hydroxydiether from M. concilii by hydroxylation, on carbon-3, of the phytanyl chain in ether linkage to the sn-2 carbon of glycerol. The structural assignment was based on identification of the novel hydroxydiether core and its methylation products by 1H NMR, 13C NMR, and mass spectroscopy. The hydroxy core lipid degraded to various products during standard methanolic HCl and sulfuric acid procedures, including a methoxy derivative (methanolic HCl) and the 3-mono-O-phytanyl-sn-glycerol

Can thermal storage assist with the electrification of heat through peak shaving?

The majority of heat in the UK comes from the combustion of natural gas, and heat is responsible for 37% of the nation’s carbon emissions. Thus the decarbonisation of heat is a major challenge. Electrification is one possible approach to decarbonisation; however, huge increases in the electrical grid’s generation and transmission capacity would be needed to meet the peaks in space heat demand during cold winter weather. Thermal energy storage (TES) may have a role to play in alleviating this problem, by shifting heat demand by hours or longer periods, enabling peaks to be shaved.This work considers the utility of two varieties of thermal energy storage for this application. Adsorption thermal storage (ATS) is a technology offering long term storage at a high energy density, but is a costly and relatively immature option. By contrast, storage of sensible heat in hot water tanks is already widespread, although it has relatively short storage duration and lower density.Here, we simulate the deployment of these technologies in a small residential neighbourhood, in tandem with demand-side management (DSM), to attempt the reduction of peaks in demand. With no storage or DSM, electrification causes peaks to increase by a factor of 2.36. Results so far suggest that both TES technologies have potential to reduce peaks, with a 14% decrease achievable by either 5 m3 of hot water storage, or 0.25 m^3 of ATS, in each dwelling. However, it is thought unlikely that adsorption storage is attractive for a purely peak shaving application, given its cost and complexity

Cinématique haute résolution des galaxies de l'échantillon SINGS et observations du H[alpha] profond de la galaxie NGC 7793

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

Optical Gas-Phase Frequency References Based on Photonic Crystal Technology:Impact of Slow Light on Molecular Absorption

Optical frequency references are devices providing well-defined and stable optical frequency responses to incoming radiation for applications such as high-precision spectroscopy and optical fibre communications. To stabilise the emission frequency of lasers, which drifts with time mostly because of fluctuations in temperature and mechanical vibrations, atomic and molecular optical transitions can be used since they show precise and well-defined frequency responses to incoming radiation. However from a practical standpoint conventional gas cell devices cannot be easily integrated into existing optical systems because of their bulky dimensions. To replace conventional absorption cells, photonic crystal fibres filled with gas-phase material are promising devices owing to their robustness, reliability, and portable characteristics. In addition they can be directly embedded into existing optical systems and they perform well in harsh environments. In this experimental study, optical gas-phase frequency references based on photonic crystal technology are realised. The gas-sensing properties of different photonic crystal fibre samples are studied and the long-term stability and reliability of fibre gas cells are demonstrated. In addition an analytical model predicting the gas-filling time in photonic crystal fibres (PCF) is developed and can be applied to any type of fibre, fibre geometry, or length. Then fibre gas cells filled with acetylene gas, a recognised frequency reference gas-phase material, have been prepared to conduct fundamental research on slow & fast light generation in optical fibres to verify the possibilities of slow light in enhancing light-matter interaction. The group velocity of light is controlled by modifying the material and structural dispersive properties of the PCF absorption cells through stimulated Brillouin scattering and cavity ring resonators, respectively. We could demonstrate that material slow light has no impact on the molecular absorption effect whereas structural slow light has an impact on the absorption efficiency scaling linearly with the group index. Such radically different responses to slow light suggest that group velocity is not the universal physical quantity scaling light-matter interaction, and that the optical absorption of molecules is more closely related to the velocity of the electromagnetic energy. Finally the impact of slow light on the molecular absorption efficiency is also evaluated in dispersion-engineered photonic crystal waveguides. We demonstrate that in planar photonic crystal waveguides the field enhancement and its evanescent fraction have more impact on the absorption efficiency than the reduction of the group velocity of light