167 research outputs found

    ‘Density hunting’: Using Google Maps to explore the city and locate suitable case study sites

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    ‘Experiencing Density’ is a project jointly led by LSE Cities and LSE London that explores resident experiences of life in London’s new high-density housing. Researching the benefits, and pitfalls, of high-density housing in the capital has become ever-more pressing in light of Mayor Sadiq Khan’s promise to build more housing for a rapidly growing population, without infringing on the Green Belt

    Dynamic Action Potential Restitution Contributes to Mechanical Restitution in Right Ventricular Myocytes From Pulmonary Hypertensive Rats

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    We investigated the steepened dynamic action potential duration (APD) restitution of rats with pulmonary artery hypertension (PAH) and right ventricular (RV) failure and tested whether the observed APD restitution properties were responsible for negative mechanical restitution in these myocytes. PAH and RV failure were provoked in male Wistar rats by a single injection of monocrotaline (MCT) and compared with saline-injected animals (CON). Action potentials were recorded from isolated RV myocytes at stimulation frequencies between 1 and 9 Hz. Action potential waveforms recorded at 1 Hz were used as voltage clamp profiles (action potential clamp) at stimulation frequencies between 1 and 7 Hz to evoke rate-dependent currents. Voltage clamp profiles mimicking typical CON and MCT APD restitution were applied and cell shortening simultaneously monitored. Compared with CON myocytes, MCT myocytes were hypertrophied; had less polarized diastolic membrane potentials; had action potentials that were triggered by decreased positive current density and shortened by decreased negative current density; APD was longer and APD restitution steeper. APD90 restitution was unchanged by exposure to the late Na⁺-channel blocker (5 μM) ranolazine or the intracellular Ca²⁺ buffer BAPTA. Under AP clamp, stimulation frequency-dependent inward currents were smaller in MCT myocytes and were abolished by BAPTA. In MCT myocytes, increasing stimulation frequency decreased contraction amplitude when depolarization duration was shortened, to mimic APD restitution, but not when depolarization duration was maintained. We present new evidence that the membrane potential of PAH myocytes is less stable than normal myocytes, being more easily perturbed by external currents. These observations can explain increased susceptibility to arrhythmias. We also present novel evidence that negative APD restitution is at least in part responsible for the negative mechanical restitution in PAH myocytes. Thus, our study links electrical restitution remodeling to a defining mechanical characteristic of heart failure, the reduced ability to respond to an increase in demand

    Modelling disease spread in real landscapes: Squirrelpox spread in southern Scotland as a case study

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    PublishedJournal ArticleThis is the author accepted manuscript. The final version is available from Associazione Teriologica Italiana via the DOI in this record.© 2016 Associazione Teriologica Italiana.There is increasing evidence that invading species can gain an advantage over native species by introducing novel disease. A clear understanding of the role of disease in the expansion of introduced and invading species is therefore essential for the conservation of native species. In this study we focus on the case study system of the UK red and grey squirrel system in which disease-mediated competition has facilitated the replacement of red squirrels by greys. We modify a deterministic model of the squirrel system in which the competition and infection dynamics are well understood to produce a stochastic model which includes a realistic representation of the heterogeneous habitat in Southern Scotland. The model is used to examine the potential spread of infection (squirrelpox virus) through the squirrel system and to examine the impact of conservation measures that control grey squirrel numbers in an attempt to contain disease spread. The results have direct implications for conservation management and we discuss how they have helped shape current and future policy for red squirrel conservation in Scotland. The methods in this study can be readily adapted to represent different systems and since the stochastic population and disease dynamics are underpinned by classical deterministic modelling frameworks the results are applicable in general.AW and PL were supported in part by SNH. AW, MB and PL were supported in part by a NERC Innovations grant NE/M021319/1

    GS100-02-41: a new large HI shell in the outer part of the Galaxy

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    Massive stars have a profound effect on the surrounding interstellar medium. They ionize and heat the neutral gas, and due to their strong winds, they swept the gas up forming large HI shells. In this way, they generate a dense shell where the physical conditions for the formation of new stars are given. The aim of this study is to analyze the origin and evolution of the large HI shell GS100-02-41 and its role in triggering star forming processes.To characterize the shell and its environs, we carry out a multi-wavelength study. We analyze he HI 21 cm line, the radio continuum, and infrared emission distributions. The analysis of the HI data shows an expanding shell structure centred at (l, b) = (100.6 deg, -2.04 deg) in the velocity range from -29 to -51.7 km/s. We infer for GS100-02-41, a kinematical distance of 2.8 +/- 0.6 kpc. Several massive stars belonging to Cep OB1 are located in projection within the large HI, shell boundaries. The analysis of the radio continuum and infrared data reveal that there is no continuum counterpart of the HI shell. On the other hand, three slightly extended radio continuum sources are observed in projection onto the dense HI shell. From their flux density determinations we infer that they are thermal in nature. An analysis of the HI emission distribution in the environs of these sources shows, for each of them, a region of low emissivity having a good morphological correlation with the ionized gas in a velocity range similar to the one where GS100-02-41 is detected. The origin of GS100-02-41 could have been mainly due to the action of the Cep OB1 massive stars located inside the HI shell. The obtained age difference between the HI shell and the HII regions, together with their relative location, led us to conclude that the ionizing stars could have been created as a consequence of the shell evolution.Comment: Accepted for publication in A&

    MP755: Eastern Regional Potato Trials 2003: Summary of NE1014 Regional Project Field Testing of New Potato Clones

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    The objectives of this regional potato trial are (1) to develop pest-resistant, early-maturing, long-dormant potato varieties that will process from cold storage; (2) to evaluate new and specialty variet­ies developed in the Northeast; (3) to determine climatic effects on performance to develop pre­dictive models for potato improvement; and (4) determine heritability/linkage relationships and improve the genetic base of tetraploid cultivated varieties. The results presented in this report reflect a portion of the activity directed toward objectives 1, 2 and 3.https://digitalcommons.library.umaine.edu/aes_miscpubs/1020/thumbnail.jp

    "From ‘What the hell is going on?’ to the ‘Mushy middle ground’ to ‘getting used to a new normal’: Young people’s biographical narratives around navigating parental dementia"

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    The number of young people who have a parent with dementia is rising as a result of improvements in diagnosis of young onset variants and demographic shifts. There has, however, been very little research focusing on this group. Accounts elicited as part of the Perceptions and Experiences of Young People With a Parent With Dementia described the period, usually some years, leading up to a diagnosis of a dementia and then the progress of the condition post diagnosis. These narratives were characterised by confusion, uncertainty, trauma and distress as the young people struggled to make sense of the significant and often extreme, behavioural and attitudinal changes that were symptoms of the illness. This paper describes and discusses how the young people experienced and navigated the temporal messiness and consequent biographical disruption arising from parental dementia

    Compensated right ventricular function of the onset of pulmonary hypertension in a rat model depends on chamber remodeling and contractile augmentation.

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    Right-ventricular function is a good indicator of pulmonary arterial hypertension (PAH) prognosis; however, how the right ventricle (RV) adapts to the pressure overload is not well understood. Here, we aimed at characterizing the time course of RV early remodeling and discriminate the contribution of ventricular geometric remodeling and intrinsic changes in myocardial mechanical properties in a monocrotaline (MCT) animal model. In a longitudinal study of PAH, ventricular morphology and function were assessed weekly during the first four weeks after MCT exposure. Using invasive measurements of RV pressure and volume, heart performance was evaluated at end of systole and diastole to quantify contractility (end-systolic elastance) and chamber stiffness (end-diastolic elastance). To distinguish between morphological and intrinsic mechanisms, a computational model of the RV was developed and used to determine the level of prediction when accounting for wall masses and unloaded volume measurements changes. By four weeks, mean pulmonary arterial pressure and elastance rose significantly. RV pressures rose significantly after the second week accompanied by significant RV hypertrophy, but RV stroke volume and cardiac output were maintained. The model analysis suggested that, after two weeks, this compensation was only possible due to a significant increase in the intrinsic inotropy of RV myocardium. We conclude that this MCT-PAH rat is a model of RV compensation during the first month after treatment, where geometric remodeling on EDPVR and increased myocardial contractility on ESPVR are the major mechanisms by which stroke volume is preserved in the setting of elevated pulmonary arterial pressure. The mediators of this compensation might themselves promote longer-term adverse remodeling and decompensation in this animal model
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