335 research outputs found
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New options in directed cupration: Studies in heteroleptic bis(amido)cuprate formation Dedicated to the memory of Jack Lewis.
The 2:1 combination of MPLi (MP = 2-methylpiperidide) with CuBr gives the novel complex [(MP)2CuLi(THF)2]2LiBr 12 and introduces the chiral ligand MP to the evolving field of Directed ortho Cupration reagents. Subsequent syntheses have focused on developing heteroleptic bis(amido) arrangements at Cu, with 1:1 mixtures of two out of MPLi, DMPLi and TMPLi (DMP = 2,6-cis-dimethylpiperidide; TMP = 2,2,6,6-tetramethylpiperidide) being reacted with CuI salts in the presence of THF. Resulting lithiocuprates reveal solid state dimers based on the heteroleptic bis(amido) formulations R2N(TMP)Cu(Br)Li2(THF)2 (R2N = MP 13; R2N = DMP 14). The heteroleptic Gilman lithiocuprate PIP(TMP)CuLi (PIP = piperidide) 15 has also been prepared. In each of 12–15, significant variations in the orientations of the amide ligands can be rationalized in terms of steric effects and, in the case of 15, stabilization of the alkali metal by Me…Li interaction is evidenced.This work was supported by the U.K. EPSRC through grant EP/J500380/1 (A P.)
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Reactions of Trimethylaluminium: Modelling the Chemical Degradation of Synthetic Lubricants
In investigating and seeking to mimic the reactivity of trimethylaluminium (TMA) with synthetic, ester-based lubricating oils, the reaction of methyl propionate was explored with 1, 2 and 3 equivalents of the organoaluminium reagent. Spectroscopic analysis points to the formation of the adduct (TMA) accompanied only by the low level 1:1 production of MeAlOCEtMe and MeAlOMe when an equimolar amount of TMA is applied. The deployment of excess TMA favours reaction to give and over (TMA) adduct formation and spectroscopy reveals that in hydrocarbon solution substitution product traps unreacted TMA to yield (TMA). The H NMR spectroscopic observation of two Al-Me signals not attributable to free TMA and in the ratio 1:4 suggests the formation of a previously only postulated, symmetrical metallacycle in MeAl (μ-Me)(μ-OCEtMe ). In the presence of , (TMA) undergoes thermally induced exchange to yield MeAl(μ-OMe)(μ-OCEtMe) and TMA. The reaction of methyl phenylacetate with TMA allows isolation of the crystalline product MeAlOCBnMe (TMA) (TMA), which allows the first observation of the Me Al(μ-Me)(μ-OR) motif in the solid state. Distances of 2.133(3) Å (Al-Me) and 1.951 Å (mean Al-Me) are recorded. The abstraction of TMA from (TMA) by the introduction of EtO has yielded , which exists as a dimer.This work was supported by Cambridge Refrigeration Technology (J.S.). The U.K. EPSRC are acknowledged for grant EP/J500380/1 (A.J.P.)
An Exact No Free Lunch Theorem for Community Detection
A precondition for a No Free Lunch theorem is evaluation with a loss function
which does not assume a priori superiority of some outputs over others. A
previous result for community detection by Peel et al. (2017) relies on a
mismatch between the loss function and the problem domain. The loss function
computes an expectation over only a subset of the universe of possible outputs;
thus, it is only asymptotically appropriate with respect to the problem size.
By using the correct random model for the problem domain, we provide a
stronger, exact No Free Lunch theorem for community detection. The claim
generalizes to other set-partitioning tasks including core/periphery
separation, -clustering, and graph partitioning. Finally, we review the
literature of proposed evaluation functions and identify functions which
(perhaps with slight modifications) are compatible with an exact No Free Lunch
theorem
What is stirring in the reservoir? Modelling mechanisms of henipavirus circulation in fruit bat hosts
Pathogen circulation among reservoir hosts is a precondition for zoonotic spillover. Unlike the acute, high morbidity infections typical in spillover hosts, infected reservoir hosts often exhibit low morbidity and mortality. Although it has been proposed that reservoir host infections may be persistent with recurrent episodes of shedding, direct evidence is often lacking. We construct a generalized SEIR (susceptible, exposed, infectious, recovered) framework encompassing 46 sub-models representing the full range of possible transitions among those four states of infection and immunity. We then use likelihood-based methods to fit these models to nine years of longitudinal data on henipavirus serology from a captive colony of Eidolon helvum bats in Ghana. We find that reinfection is necessary to explain observed dynamics; that acute infectious periods may be very short (hours to days); that immunity, if present, lasts about 1–2 years; and that recurring latent infection is likely. Although quantitative inference is sensitive to assumptions about serology, qualitative predictions are robust. Our novel approach helps clarify mechanisms of viral persistence and circulation in wild bats, including estimated ranges for key parameters such as the basic reproduction number and the duration of the infectious period. Our results inform how future field-based and experimental work could differentiate the processes of viral recurrence and reinfection in reservoir hosts.
This article is part of the theme issue ‘Dynamic and integrative approaches to understanding pathogen spillover’
Interpreting and acting upon home blood pressure readings: A qualitative study
This article is made available through the Brunel Open Access Publishing Fund. Copyright @ 2013 Vasileiou et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.Background: Recent guidelines recognize the importance of home blood pressure monitoring (HBPM) as an adjunct to clinical measurements. We explored how people who have purchased and use a home blood pressure (BP) monitor make sense of, and act upon, readings and how they communicate with their doctor about the practice of home monitoring.
Methods: A qualitative study was designed and participants were purposively recruited from several areas in England, UK. Semi-structured in-depth interviews were conducted with 18 users of home BP monitors. The transcribed data were thematically analysed.
Results: Interpretation of home BP readings is complex, and is often characterised by uncertainty. People seek to assess value normality using ‘rules of thumb’, and often aim to identify the potential causes of the readings. This is done by drawing on lay models of BP function and by contextualising the readings to personal circumstances. Based on the perceived causes of the problematic readings, actions are initiated, mostly relating to changes in daily routines. Contacting the doctor was more likely when the problematic readings persisted and could not be easily explained, or when participants did not succeed in regulating their BP through their other interventions. Most users had notified their doctor of the practice of home monitoring, but medical involvement varied, with some participants reporting disinterest or reservations by doctors.
Conclusions: Involvement from doctors can help people overcome difficulties and resolve uncertainties around the interpretation of home readings, and ensure that the rules of thumb are appropriate. Home monitoring can be used to strengthen the patient-clinician relationship
We are all one together : peer educators\u27 views about falls prevention education for community-dwelling older adults - a qualitative study
Background: Falls are common in older people. Despite strong evidence for effective falls prevention strategies, there appears to be limited translation of these strategies from research to clinical practice. Use of peers in delivering falls prevention education messages has been proposed to improve uptake of falls prevention strategies and facilitate translation to practice. Volunteer peer educators often deliver educational presentations on falls prevention to community-dwelling older adults. However, research evaluating the effectiveness of peer-led education approaches in falls prevention has been limited and no known study has evaluated such a program from the perspective of peer educators involved in delivering the message. The purpose of this study was to explore peer educators’ perspective about their role in delivering peer-led falls prevention education for community-dwelling older adults.
Methods: A two-stage qualitative inductive constant comparative design was used.In stage one (core component) focus group interviews involving a total of eleven participants were conducted. During stage two (supplementary component) semi-structured interviews with two participants were conducted. Data were analysed thematically by two researchers independently. Key themes were identified and findings were displayed in a conceptual framework.
Results: Peer educators were motivated to deliver educational presentations and importantly, to reach an optimal peer connection with their audience. Key themes identified included both personal and organisational factors that impact on educators’ capacity to facilitate their peers’ engagement with the message. Personal factors that facilitated message delivery and engagement included peer-to-peer connection and perceived credibility, while barriers included a reluctance to accept the message that they were at risk of falling by some members in the audience. Organisational factors, including ongoing training for peer educators and formative feedback following presentations, were perceived as essential because they affect successful message delivery.
Conclusions: Peer educators have the potential to effectively deliver falls prevention education to older adults and influence acceptance of the message as they possess the peer-to-peer connection that facilitates optimal engagement. There is a need to consider incorporating learnings from this research into a formal large scale evaluation of the effectiveness of the peer education approach in reducing falls in older adults
Serum methylarginines and spirometry-measured lung function in older adults
Rationale: Methylarginines are endogenous nitric oxide synthase inhibitors that have been implicated in animal models of lung disease but have not previously been examined for their association with spirometric measures of lung function in humans.
Objectives: This study measured serum concentrations of asymmetric and symmetric dimethylarginine in a representative sample of older community-dwelling adults and determined their association with spirometric lung function measures.
Methods: Data on clinical, lifestyle, and demographic characteristics, methylated arginines, and L-arginine (measured using LC-MS/MS) were collected from a population-based sample of older Australian adults from the Hunter Community Study.
The five key lung function measures included as outcomes were Forced Expiratory Volume in 1 second, Forced Vital Capacity, Forced Expiratory Volume in 1 second to Forced Vital Capacity ratio, Percent Predicted Forced Expiratory Volume in 1 second, and Percent Predicted Forced Vital Capacity.
Measurements and Main Results: In adjusted analyses there were statistically significant independent associations between a) higher asymmetric dimethylarginine, lower Forced Expiratory Volume in 1 second and lower Forced Vital Capacity; and b) lower L-arginine/asymmetric dimethylarginine ratio, lower Forced Expiratory Volume in 1 second, lower Percent Predicted Forced Expiratory Volume in 1 second and lower Percent Predicted Forced Vital Capacity. By contrast, no significant associations were observed between symmetric dimethylarginine and lung function.
Conclusions: After adjusting for clinical, demographic, biochemical, and pharmacological confounders, higher serum asymmetric dimethylarginine was independently associated with a reduction in key measures of lung function. Further research is needed to determine if methylarginines predict the decline in lung function
Domesticated animals as hosts of henipaviruses and filoviruses: A systematic review
Bat-borne viruses carry undeniable risks to the health of human beings and animals, and there is growing recognition of the need for a 'One Health' approach to understand their frequently complex spill-over routes. While domesticated animals can play central roles in major spill- over events of zoonotic bat-borne viruses, for example during the pig- amplified Malaysian Nipah virus outbreak of 1998-1999, the extent of their potential to act as bridging or amplifying species for these viruses has not been characterised systematically. This review aims to compile current knowledge on the role of domesticated animals as hosts of two types of bat-borne viruses, henipaviruses and filoviruses. A systematic literature search of these virus-host interactions in domesticated animals identified 72 relevant studies, which were categorised by year, location, design and type of evidence generated. The review then focusses on Africa as a case study, comparing research efforts in domesticated animals and bats with the distributions of documented human cases. Major gaps remain in our knowledge of the potential ability of domesticated animals to contract or spread these zoonoses. Closing these gaps will be necessary to fully evaluate and mitigate spill-over risks of these viruses, especially with global agricultural intensification
Comparison of depression and anxiety symptom networks in reporters and non-reporters of lifetime trauma in two samples of differing severity
Background: Reported trauma is associated with differences in the course and outcomes of depression and anxiety. However, no research has explored the association between reported trauma and patterns of clinically relevant symptoms of both depression and anxiety. /
Methods: We used network analysis to investigate associations between reported trauma and depression and anxiety symptom interactions in affected individuals from the Genetic Links to Anxiety and Depression (GLAD) Study (n = 17720), and population volunteers from the UK Biobank (n = 11120). Participants with current moderate symptoms of depression or anxiety were grouped into reporters and non-reporters of lifetime trauma. Networks of 16 depression and anxiety symptoms in the two groups were compared using the network comparison test. /
Results: In the GLAD Study, networks of reporters and non-reporters of lifetime trauma did not differ on any metric. In the UK Biobank, the symptom network of reporters had significantly greater density (7.80) than the network of non-reporters (7.05). /
Limitations: The data collected in the GLAD Study and the UK Biobank are self-reported with validated or semi-validated questionnaires. /
Conclusions: Reported lifetime trauma was associated with stronger interactions between symptoms of depression and anxiety in population volunteers. Differences between reporters and non-reporters may not be observed in individuals with severe depression and/or anxiety due to limited variance in the presentation of disorder
Preventing or inventing? Understanding the effects of non-prescriptive design briefs
© 2016, The Author(s). This paper discusses observations of an architecture and environmental engineering undergraduate design studio project assigned to 4th year students at a UK university. In the UK, most architecture courses are characterised by a high proportion of design studio teaching supported by varying amount of technical modules that include environmental and construction learning. Recent scholarship on sustainability education in architecture, discusses the necessity for new approaches that enhance transdisciplinarity, autonomy and independent decision-making. However, despite increasing importance to both practice and policy, few empirical or theoretical examples account for the implications or experiences of such an approach. This study presents the experiences of an architecture and environmental engineering design studio whereby studio activities are closely interlinked with technical engineering enquiry and experiment. Specifically, the research examines the challenges and opportunities students face when assigned a design project that attempts to translate independently derived briefs into novel architectural environmentally engineered interpretations. The analysis draws on a series of ethnographic narrative and visual observations carried over a period of 6months. The implications of the findings are threefold. First, the analysis shows the opportunities an integrated cross-disciplinary approach can offer, where the gap between creative and technical domains is narrowed. Second, the study presents some of the challenges faced by increased autonomy and lack of prescription that students encounter. Third, the paper contributes to an emerging agenda of sustainability education in the built environment by offering valuable insights into the benefits and difficulties cross-disciplinary approaches pose to architectural education
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