Learning difficulties: collaborative inter-organisational information system use within UK retail supply networks

Inter-organisational information systems (IOIS) have been introduced to support collaborative retail supply relationships, yet how these systems are used is not well understood. This paper presents analysis of an ideographic case study of a dynamic United Kingdom grocery sector supply network. Using Archer's (1995) social change theory we explore how changes to buyer-supplier relationship structures re-conditioned individual actors' situational logics in a way that created network learning difficulties. Our analysis shows how actors' inter-organisational information system use reinforced pre-existing bargaining positions and improved already powerful actors' relative negotiating strength. This paper demonstrates the value of multi-level analysis in furthering understanding of the complex relationships between processes of network and individual learning

Well-defined coinage metal transfer agents for the synthesis of NHC-based nickel, rhodium and palladium macrocycles

With a view to use as carbene transfer agents, well-defined silver(I) and copper(I) complexes of a macrocyclic NHC-based pincer ligand, bearing a central lutidine donor and a dodecamethylene spacer [CNC–(CH2)12, 1], have been prepared. Although the silver adduct is characterised by X-ray diffraction as a dinuclear species anti-[Ag(μ-1)]22+, variable temperature measurements indicate dynamic structural interchange in solution involving fragmentation into mononuclear [Ag(1)]+ on the NMR time scale. In contrast, a mononuclear structure is evident in both solution and the solid-state for the analogous copper adduct partnered with the weakly coordinating [BArF4]− counter anion. A related copper derivative, bearing instead the more coordinating cuprous bromide dianion [Cu2Br4]2−, is notable for the adoption of an interesting tetranuclear assembly in the solid-state, featuring two cuprophilic interactions and two bridging NHC donors, but is not retained on dissolution. Coinage metal precursors [M(1)]n[BArF4]n (M = Ag, n = 2; M = Cu, n = 1) both act as carbene transfer agents to afford palladium, rhodium and nickel complexes of 1 and the effectiveness of these precursors has been evaluated under equivalent reaction conditions

Rhodium complexes of NHC-based pincer ligands: catalysis and reactions through rings

N-heterocyclic carbenes (NHCs) are robust and versatile ancillary ligands for a wide range of metals. Incorporation of these strong σ-donors into mer-tridentate pincer frameworks confers greater thermal stability, representing an amalgamation of favourable ligand design principles that underpin many advances being made in contemporary organometallic chemistry and catalysis. This project aims to develop understanding of the mechanistic organometallic chemistry of terminal alkyne coupling reactions promoted by rhodium complexes of NHC-based pincer ligands, with the hope of exploiting this methodology in the formation of mechanically interlocked structures of macrocyclic variants of differing ring size. Following development of a mild copper-based transmetallation procedure, rhodium(I) ethylene complexes of a series of NHC-based pincer ligands were prepared (viz. 11-n; n = Me, 12, 14, 16). The acyclic complex 11-Me was found to be a highly effective pre-catalyst for the head-to-tail dimerisation of aryl alkynes to afford gem-enynes under mild conditions and curiously their subsequent annulation into bicyclo[4.2.0]octa-1,5,7-trienes. Through in situ reaction monitoring using NMR spectroscopy, kinetic studies and computational modelling, the mechanism and factors which influence the selectivity of the alkyne dimerisation reaction were probed. Terminal alkyne coupling of bulky alkynes through the macrocyclic annuli of 11-n (n = 12, 14, 16) are associated with increased selectivity for E-enynes products, which were formed exclusively in the case of n = 12 and 14, as a consequence of the unique ligand topology. Using these and related results the prospects for synthesising interlocked assemblies, comprising an NHC-based pincer macrocycle and an entrapped hydrocarbon axle, have been critically assessed

Divergent stereoisomers of molybdenum carbonyl complexes of NHC-based pincer ligands

The first molybdenum complexes of widely used NHC-based CNC and C^N^C pincer ligands are described, viz. [Mo(L)(CO)3] (L = 2,6-bis(mesityl-imidazolylidene)pyridine ≡ CNC-Mes, 1; α,α’-(diimidazolylidene-dodecamethylene)lutidine ≡ C^N^C-12, 2). These complexes have been thoroughly characterised in solution and the solid-state, revealing different stereochemical preferences of the tridentate ligands depending on the nature of the scaffold. In the case of flexible C^N^C-12 an uncommon fac-coordination geometry is observed, whilst the complex of rigid CNC-Mes adopts the expected mer-configuration. For the combination of donors associated with the ligands, DFT calculations establish preferential fac-coordination, however, within the CNC (ΔΔG = +63.1 kJ·mol-1) and C^N^C (ΔΔG = +20.0 kJ·mol-1) scaffolds this conformation is significantly destabilised relative to the mer-alternative

Systematic Review and Meta-Analysis of Psychosocial Risk Factors for Stroke

Background Several studies have assessed the link between psychosocial risk factors and stroke; however, the results are inconsistent. We have conducted a systemic review and meta-analysis of cohort or case-control studies to ascertain the association between psychosocial risk factors (psychological, vocational, behavioral, interpersonal and neuropsychological) and the risk of stroke. Methods Systematic searches were undertaken in MEDLINE, EMBASE, CINAHL, PsycInfo and the Cochrane Database of Systematic Reviews between 2000 and January 2017. Two reviewers independently screened titles, abstracts and full texts. One reviewer assessed quality and extracted data, which was checked by a second reviewer. For studies that reported risk estimates, a meta-analysis was performed. Results We identified 41 cohort studies and five case-control studies. No neuropsychological papers were found. Overall pooled adjusted estimates showed that all other psychosocial risk factors were independent risk factors for stroke. Psychological factors increased the risk of stroke by 39% (HR 1.39 95% CI:1.27;1.51), vocational by 35% (HR 1.35 95% CI: 1.20;1.51), and interpersonal by 16% (HR 1.16 95% CI:1.03;1.31). and the effects of behavioral factors were equivocal (HR 0.94 95% CI: 0.20;4.31). The meta-analyses were affected by heterogeneity. Conclusions Psychosocial risk factors are associated with an increased risk of strok

The effect of stress on the expression of the amyloid precursor protein in rat brain

AbstractThe abnormal processing of the amyloid precursor protein (APP) is a pivotal event in the development of the unique pathology that defines Alzheimer's disease (AD). Stress, and the associated increase in corticosteroids, appear to accelerate brain ageing and may increase vulnerability to Alzheimer's disease via altered APP processing. In this study, rats were repeatedly exposed to an unavoidable stressor, an open elevated platform. Previous studies in this laboratory have shown that a single exposure produces a marked increase in plasma corticosterone levels but animals develop tolerance to this effect between 10 and 20 daily sessions. Twenty-four hours after stress, there was an increase in the ratio of the deglycosylated form of APP in the particulate fraction of the brain, which subsequently habituated after 20 days. The levels of soluble APP (APPs) tended to be lower in the stress groups compared to controls except for a significant increase in the hippocampus after 20 days of platform exposure. Since APPs is reported to have neurotrophic properties, this increased release may represent a neuroprotective response to repeated stress. It is possible that the ability to mount this response decreases with age thus increasing the vulnerability to stress-induced AD-related pathology

The Torpid State:Recent Advances in Metabolic Adaptations and Protective Mechanisms(dagger)

Torpor and hibernation are powerful strategies enabling animals to survive periods of low resource availability. The state of torpor results from an active and drastic reduction of an individual's metabolic rate (MR) associated with a relatively pronounced decrease in body temperature. To date, several forms of torpor have been described in all three mammalian subclasses, i.e., monotremes, marsupials, and placentals, as well as in a few avian orders. This review highlights some of the characteristics, from the whole organism down to cellular and molecular aspects, associated with the torpor phenotype. The first part of this review focuses on the specific metabolic adaptations of torpor, as it is used by many species from temperate zones. This notably includes the endocrine changes involved in fat- and food-storing hibernating species, explaining biomedical implications of MR depression. We further compare adaptive mechanisms occurring in opportunistic vs. seasonal heterotherms, such as tropical and sub-tropical species. Such comparisons bring new insights into the metabolic origins of hibernation among tropical species, including resistance mechanisms to oxidative stress. The second section of this review emphasizes the mechanisms enabling heterotherms to protect their key organs against potential threats, such as reactive oxygen species, associated with the torpid state. We notably address the mechanisms of cellular rehabilitation and protection during torpor and hibernation, with an emphasis on the brain, a central organ requiring protection during torpor and recovery. Also, a special focus is given to the role of an ubiquitous and readily-diffusing molecule, hydrogen sulfide (H2S), in protecting against ischemia-reperfusion damage in various organs over the torpor-arousal cycle and during the torpid state. We conclude that (i) the flexibility of torpor use as an adaptive strategy enables different heterothermic species to substantially suppress their energy needs during periods of severely reduced food availability, (ii) the torpor phenotype implies marked metabolic adaptations from the whole organism down to cellular and molecular levels, and (iii) the torpid state is associated with highly efficient rehabilitation and protective mechanisms ensuring the continuity of proper bodily functions. Comparison of mechanisms in monotremes and marsupials is warranted for understanding the origin and evolution of mammalian torpor

Influence du quartier résidentiel et des problèmes de comportement extériorisés sur le rendement scolaire des adolescents

This study investigates if the socio-economic composition, as well as the physical and social disorder of neighbourhoods, were associated with academic performance among Quebec school children, with and without conduct problems, aged 12 to 15 (N = 630). In particular, the moderating role of conduct problems was explored. Findings indicated that physical and social disorder, along with the percentage of low-income individuals in the neighbourhood, were associated with some aspects of academic performance. Conduct problems did, however, moderate between neighbourhood variables and school performance. The implications of these findings will also be discussed.Cette étude vérifie si la composition et l’organisation sociale du quartier résidentiel sont associées au rendement scolaire d’élèves québécois âgés de 12 à 15 ans (N = 630). L’effet modérateur des problèmes de comportement extériorisés sur ces associations est aussi analysé. Les résultats montrent que le désordre physique et social du quartier ainsi que son niveau de désavantage socioéconomique sont associés à des aspects du rendement scolaire des élèves au-delà de leurs caractéristiques familiales et individuelles. La présence de problèmes de comportement chez les jeunes modère cependant certaines de ces associations. Ces résultats sont discutés en fonction des retombées pour la pratique

Terminal alkyne coupling reactions through a ring : effect of ring size on rate and regioselectivity

Terminal alkyne coupling reactions promoted by rhodium(I) complexes of macrocyclic NHC‐based pincer ligands – which feature dodecamethylene, tetradecamethylene or hexadecamethylene wingtip linkers viz. [Rh(CNC‐n)(C2H4)][BArF4] (n = 12, 14, 16; ArF = 3,5‐(CF3)2C6H3) – have been investigated, using the bulky alkynes HC≡CtBu and HC≡CAr′ (Ar′ = 3,5‐tBu2C6H3) as substrates. These stoichiometric reactions proceed with formation of rhodium(III) alkynyl alkenyl derivatives and produce rhodium(I) complexes of conjugated 1,3‐enynes by C–C bond reductive elimination through the annulus of the ancillary ligand. The intermediates are formed with orthogonal regioselectivity, with E‐alkenyl complexes derived from HC≡CtBu and gem‐alkenyl complexes derived from HC≡CAr′, and the reductive elimination step is appreciably affected by the ring size of the macrocycle. For the homocoupling of HC≡CtBu, E‐tBuC≡CCH=CHtBu is produced via direct reductive elimination from the corresponding rhodium(III) alkynyl E‐alkenyl derivatives with increasing efficacy as the ring is expanded. In contrast, direct reductive elimination of Ar′C≡CC(=CH2)Ar′ is encumbered relative to head‐to‐head coupling of HC≡CAr′ and it is only with the largest macrocyclic ligand studied that the two processes are competitive. These results showcase how macrocyclic ligands can be used to interrogate the mechanism and tune the outcome of terminal alkyne coupling reactions, and are discussed with reference to catalytic reactions mediated by the acyclic homologue [Rh(CNC‐Me)(C2H4)][BArF4] and solvent effects