AC impedance study of degradation of porous nickel battery electrodes

AC impedance spectra of porous nickel battery electrodes were recorded periodically during charge/discharge cycling in concentrated KOH solution at various temperatures. A transmission line model (TLM) was adopted to represent the impedance of the porous electrodes, and various model parameters were adjusted in a curve fitting routine to reproduce the experimental impedances. Degradation processes were deduced from changes in model parameters with electrode cycling time. In developing the TLM, impedance spectra of planar (nonporous) electrodes were used to represent the pore wall and backing plate interfacial impedances. These data were measured over a range of potentials and temperatures, and an equivalent circuit model was adopted to represent the planar electrode data. Cyclic voltammetry was used to study the characteristics of the oxygen evolution reaction on planar nickel electrodes during charging, since oxygen evolution can affect battery electrode charging efficiency and ultimately electrode cycle life if the overpotential for oxygen evolution is sufficiently low

Listening to young people’s views of the coast:Living Coast Youth Voice

We have summarised the knowledge that was co-created with young people here. However, we would like to encourage those adults who planned to read just this summary to also hear directly form the young people by reading Chapter 3. Introduction Living Coast was a national partnership pilot project developed by Natural England1 (an organisation that looks after nature and landscapes in England). Natural England wants to help people from all walks-of-life enjoy the benefits of a new long distance path around England: the England Coast Path. By 2020, the path will stretch for approximately 2,700 miles around our beautiful English coastline and open up new stretches of the coastline. Natural England wants to understand how and why young people already use and enjoy the coast, and why others do not (or cannot). They want to know what can be done to help as many young people as possible benefit from the spectacular views, sea air, exercise and nature that the path and surrounding areas offer. In this research, we worked with young people aged 11 – 18 to create new knowledge about what makes it easy or hard for them to make the most of the coast, and what they suggest would help. This is important because there is little other evidence about this, nationally. This research took place in Barrow-in-Furness in Cumbria – a place with a high quality natural environment and areas that fall in the bottom 10% and 3% nationally on measures of deprivation. Cumbria was one of three Living Coast pilot areas in 2018/19. The other two are on the Durham Heritage Coast and the Solent. All three will inform how Natural England and its partners develop work at the coast.2 Research focus The study asked the following research questions: Q What do you think of the coast? Q How do you use the coast? Q How do you benefit from the coast? Q What makes it easy to go to, and enjoy, the coast? Q What makes it hard to go to, and enjoy, the coast? Q What would help you to go more often? Q What suggestions would you make to Natural England about how they can help? Methods used Our methods mixed and blended methods, techniques and principles from participation practice and social science. To do this we: 2 1. In total, we met 59 young people from a mix of ages, genders, ethnicities, and distances from the coast, prioritising those who live in areas that fall in the lowest 3% or 10% in the Indices of Multiple Deprivation. 2. Set up a Participatory Advisory Group (PAG) of eight young people, aged 14, to be our research advisors, comment on our methods and help us interpret and analyse our findings. 3. Met with 47 young people in six groups, from a range of community and educational settings, for 90-minutes each. During these sessions, we worked with young people to create maps, discuss their good and bad experiences, ease of getting to the coast, and the influence of money, jobs, belonging and culture to their views of the coast. 4. Summarised what young people said in this first round in pictures. 5. Ran two ‘Creative Horizons’ events a fortnight later, in two sessions when 22 young people (of those who had taken part in the mapping sessions) were joined by 4 new young people. In these sessions young people took charge of which topics to explore and how to create new knowledge through art, story, rap, music, poems, drama, or discussion. 6. Faithfully reported what young people said in this report and in a film. Findings We found that young people have a mix of attitudes towards the coast, with some finding it a place of enjoyment, peace, and adventure and others finding it boring, uncomfortable and a place of natural and human dangers. Young people go to a mix of places. Some are familiar beaches, which are closer to home and easier to get to, and others are destinations young people enjoy with friends and family but require transport to get to. Walking and dog walking were most often mentioned as activities to do at the coast, with some saying they swam in the sea but many others not mentioning swimming at all or saying they couldn’t swim. For a few, cycling was a key part of enjoying the coast and a couple of young people mentioned anglin g and water sports. Young people in all groups described psychological, physical and social wellbeing benefits of being by the sea. They said that it helped them cope with stress, be fitter and enjoy time with family and friends. The things that made it easier to go included: their own attitudes and confidence, being able to get there, having someone available to go with, feeling safe and belonging and also the time of year and the weather. The barriers to going to the seaside were numerous and interconnected and particularly hard for young people living with multiple pressures and disadvantages. Negative personal attitudes and fears included boredom and anxiety, such as about risks or body shaming. A range of issues around social barriers included not feeling safe from attack, feeling they didn’t belong, that adults and peers were judging them badly as well as outright racism, sexism and homophobia. Young people also said they lacked information about where to go, how to get there, what to do once there, natural risks such as tides, quick sands and rock falls. Getting there and affording to go were practical barriers, as was having someone available to go with them. Litter and dirty beaches deter young people. At this exposed location, bad weather with fierce winds and driving rain can make it too unpleasant to go. Young peoples’ messages to the Natural England and its partners about enjoying the coast: Help make it safe (from attack and by changing adult attitudes toward us) 3 Help us get there Give us information Provide affordable events and activities Run nature trips Provide shelter

Ecological equivalence: a realistic assumption for niche theory as a testable alternative to neutral theory

Hubbell's 2001 neutral theory unifies biodiversity and biogeography by modelling steady-state distributions of species richness and abundances across spatio-temporal scales. Accurate predictions have issued from its core premise that all species have identical vital rates. Yet no ecologist believes that species are identical in reality. Here I explain this paradox in terms of the ecological equivalence that species must achieve at their coexistence equilibrium, defined by zero net fitness for all regardless of intrinsic differences between them. I show that the distinction of realised from intrinsic vital rates is crucial to evaluating community resilience. An analysis of competitive interactions reveals how zero-sum patterns of abundance emerge for species with contrasting life-history traits as for identical species. I develop a stochastic model to simulate community assembly from a random drift of invasions sustaining the dynamics of recruitment following deaths and extinctions. Species are allocated identical intrinsic vital rates for neutral dynamics, or random intrinsic vital rates and competitive abilities for niche dynamics either on a continuous scale or between dominant-fugitive extremes. Resulting communities have steady-state distributions of the same type for more or less extremely differentiated species as for identical species. All produce negatively skewed log-normal distributions of species abundance, zero-sum relationships of total abundance to area, and Arrhenius relationships of species to area. Intrinsically identical species nevertheless support fewer total individuals, because their densities impact as strongly on each other as on themselves. Truly neutral communities have measurably lower abundance/area and higher species/abundance ratios. Neutral scenarios can be parameterized as null hypotheses for testing competitive release, which is a sure signal of niche dynamics. Ignoring the true strength of interactions between and within species risks a substantial misrepresentation of community resilience to habitat los

Signatures of Young Star Formation Activity Within Two Parsecs of Sgr A*

We present radio and infrared observations indicating on-going star formation activity inside the $\sim2-5$ pc circumnuclear ring at the Galactic center. Collectively these measurements suggest a continued disk-based mode of on-going star formation has taken place near Sgr A* over the last few million years. First, VLA observations with spatial resolution 2.17$"\times0.81"$ reveal 13 water masers, several of which have multiple velocity components. The presence of interstellar water masers suggests gas densities that are sufficient for self-gravity to overcome the tidal shear of the 4$\times10^6$ \msol\, black hole. Second, SED modeling of stellar sources indicate massive YSO candidates interior to the molecular ring, supporting in-situ star formation near Sgr A* and appear to show a distribution similar to that of the counter-rotating disks of $\sim$100 OB stars orbiting Sgr A*. Some YSO candidates (e.g., IRS~5) have bow shock structures suggesting that they have have gaseous disks that are phototoevaporated and photoionized by the strong radiation field. Third, we detect clumps of SiO (2-1) and (5-4) line emission in the ring based on CARMA and SMA observations. The FWHM and luminosity of the SiO emission is consistent with shocked protostellar outflows. Fourth, two linear ionized features with an extent of $\sim0.8$ pc show blue and redshifted velocities between $+50$ and $-40$ \kms, suggesting protostellar jet driven outflows with mass loss rates of $\sim5\times10^{-5}$ solar mass yr$^{-1}$. Finally, we present the imprint of radio dark clouds at 44 GHz, representing a reservoir of molecular gas that feeds star formation activity close to Sgr A*.Comment: 38 pages, 10 figures, ApJ (in press

Waves on the surface of the Orion molecular cloud

Massive stars influence their parental molecular cloud, and it has long been suspected that the development of hydrodynamical instabilities can compress or fragment the cloud. Identifying such instabilities has proved difficult. It has been suggested that elongated structures (such as the `pillars of creation') and other shapes arise because of instabilities, but alternative explanations are available. One key signature of an instability is a wave-like structure in the gas, which has hitherto not been seen. Here we report the presence of `waves' at the surface of the Orion molecular cloud near where massive stars are forming. The waves seem to be a Kelvin-Helmholtz instability that arises during the expansion of the nebula as gas heated and ionized by massive stars is blown over pre-existing molecular gas.Comment: Preprint of publication in Natur

Separation of quadrupolar and magnetic contributions to spin-lattice relaxation in the case of a single isotope

We present a NMR pulse double-irradiation method which allows one to separate magnetic from quadrupolar contributions in the spin-lattice relaxation. The pulse sequence fully saturates one transition while another is observed. In the presence of a Delta m = 2 quadrupolar contribution, the intensity of the observed line is altered compared to a standard spin-echo experiment. We calculated analytically this intensity change for spins I=1, 3/2, 5/2, thus providing a quantitative analysis of the experimental results. Since the pulse sequence we used takes care of the absorbed radio-frequency power, no problems due to heating arise. The method is especially suited when only one NMR sensitive isotope is available. Different cross-checks were performed to prove the reliability of the obtained results. The applicability of this method is demonstrated by a study of the plane oxygen 17O (I = 5/2) in the high-temperature superconductor YBa_2Cu_4O_8: the 17O spin-lattice relaxation rate consists of magnetic as well as quadrupolar contributions.Comment: 7 pages, 6 figure

Gravitational redshift of galaxies in clusters as predicted by general relativity

The theoretical framework of cosmology is mainly defined by gravity, of which general relativity is the current model. Recent tests of general relativity within the \Lambda Cold Dark Matter (CDM) model have found a concordance between predictions and the observations of the growth rate and clustering of the cosmic web. General relativity has not hitherto been tested on cosmological scales independent of the assumptions of the \Lambda CDM model. Here we report observation of the gravitational redshift of light coming from galaxies in clusters at the 99 per cent confidence level, based upon archival data. The measurement agrees with the predictions of general relativity and its modification created to explain cosmic acceleration without the need for dark energy (f(R) theory), but is inconsistent with alternative models designed to avoid the presence of dark matter.Comment: Published in Nature issued on 29 September 2011. This version includes the Letter published there as well as the Supplementary Information. 23 pages, 7 figure

Tracing the Bipolar Outflow from Orion Source I

Using CARMA, we imaged the 87 GHz SiO v=0 J=2-1 line toward Orion-KL with 0.45 arcsec angular resolution. The maps indicate that radio source I drives a bipolar outflow into the surrounding molecular cloud along a NE--SW axis, in agreement with the model of Greenhill et al. (2004). The extended high velocity outflow from Orion-KL appears to be a continuation of this compact outflow. High velocity gas extends farthest along a NW--SE axis, suggesting that the outflow direction changes on time scales of a few hundred years.Comment: 4 pages, 4 figures; accepted for publication in Ap J Letter

CARMA Large Area Star Formation Survey: Observational Analysis of Filaments in the Serpens South Molecular Cloud

We present the N2H+(J=1-0) map of the Serpens South molecular cloud obtained as part of the CARMA Large Area Star Formation Survey (CLASSy). The observations cover 250 square arcminutes and fully sample structures from 3000 AU to 3 pc with a velocity resolution of 0.16 km/s, and they can be used to constrain the origin and evolution of molecular cloud filaments. The spatial distribution of the N2H+ emission is characterized by long filaments that resemble those observed in the dust continuum emission by Herschel. However, the gas filaments are typically narrower such that, in some cases, two or three quasi-parallel N2H+ filaments comprise a single observed dust continuum filament. The difference between the dust and gas filament widths casts doubt on Herschel ability to resolve the Serpens South filaments. Some molecular filaments show velocity gradients along their major axis, and two are characterized by a steep velocity gradient in the direction perpendicular to the filament axis. The observed velocity gradient along one of these filaments was previously postulated as evidence for mass infall toward the central cluster, but these kind of gradients can be interpreted as projection of large-scale turbulence.Comment: 12 pages, 4 figures, published in ApJL (July 2014

Retrospective harm benefit analysis of pre-clinical animal research for six treatment interventions

The harm benefit analysis (HBA) is the cornerstone of animal research regulation and is considered to be a key ethical safeguard for animals. The HBA involves weighing the anticipated benefits of animal research against its predicted harms to animals but there are doubts about how objective and accountable this process is.i. To explore the harms to animals involved in pre-clinical animal studies and to assess these against the benefits for humans accruing from these studies; ii. To test the feasibility of conducting this type of retrospective HBA.Data on harms were systematically extracted from a sample of pre-clinical animal studies whose clinical relevance had already been investigated by comparing systematic reviews of the animal studies with systematic reviews of human studies for the same interventions (antifibrinolytics for haemorrhage, bisphosphonates for osteoporosis, corticosteroids for brain injury, Tirilazad for stroke, antenatal corticosteroids for neonatal respiratory distress and thrombolytics for stroke). Clinical relevance was also explored in terms of current clinical practice. Harms were categorised for severity using an expert panel. The quality of the research and its impact were considered. Bateson's Cube was used to conduct the HBA.The most common assessment of animal harms by the expert panel was 'severe'. Reported use of analgesia was rare and some animals (including most neonates) endured significant procedures with no, or only light, anaesthesia reported. Some animals suffered iatrogenic harms. Many were kept alive for long periods post-experimentally but only 1% of studies reported post-operative care. A third of studies reported that some animals died prior to endpoints. All the studies were of poor quality. Having weighed the actual harms to animals against the actual clinical benefits accruing from these studies, and taking into account the quality of the research and its impact, less than 7% of the studies were permissible according to Bateson's Cube: only the moderate bisphosphonate studies appeared to minimise harms to animals whilst being associated with benefit for humans.This is the first time the accountability of the HBA has been systematically explored across a range of pre-clinical animal studies. The regulatory systems in place when these studies were conducted failed to safeguard animals from severe suffering or to ensure that only beneficial, scientifically rigorous research was conducted. Our findings indicate a pressing need to: i. review regulations, particularly those that permit animals to suffer severe harms; ii. reform the processes of prospectively assessing pre-clinical animal studies to make them fit for purpose; and iii. systematically evaluate the benefits of pre-clinical animal research to permit a more realistic assessment of its likely future benefits