Temporal and spatial variations in phytoplankton productivity in surface waters of a warm-temperate, monomictic lake in New Zealand

Surface phytoplankton productivity measurements were carried out in morphologically complex Lake Rotoiti with the objective of defining variations between sites and seasons, and the dominant environmental drivers of these variations. Measurements were carried out monthly at two depths at each of three morphologically diverse stations for 1 year throughout the lake. Productivity at the surface of the shallow embayment was significantly higher in most months of the year compared with the surface of the other two stations but there were no significant differences from September to December 2004. There were no relationships between measured environmental variables and primary productivity or specific production. Inorganic nutrient concentrations at the surface of the shallow station were low throughout the whole year but at the other two stations they showed a typical pattern for monomictic lakes of higher levels during winter mixing and declining concentrations during thermal stratification. The high variability between sites found in this study indicates that it is important to account for local differences in productivity in morphologically diverse lakes, and that whole lake productivity estimates may vary greatly depending on the location and depth of productivity measurements

Density-Dependence as a Size-Independent Regulatory Mechanism

The growth function of populations is central in biomathematics. The main dogma is the existence of density dependence mechanisms, which can be modelled with distinct functional forms that depend on the size of the population. One important class of regulatory functions is the $\theta$-logistic, which generalises the logistic equation. Using this model as a motivation, this paper introduces a simple dynamical reformulation that generalises many growth functions. The reformulation consists of two equations, one for population size, and one for the growth rate. Furthermore, the model shows that although population is density-dependent, the dynamics of the growth rate does not depend either on population size, nor on the carrying capacity. Actually, the growth equation is uncoupled from the population size equation, and the model has only two parameters, a Malthusian parameter $\rho$ and a competition coefficient $\theta$. Distinct sign combinations of these parameters reproduce not only the family of $\theta$-logistics, but also the van Bertalanffy, Gompertz and Potential Growth equations, among other possibilities. It is also shown that, except for two critical points, there is a general size-scaling relation that includes those appearing in the most important allometric theories, including the recently proposed Metabolic Theory of Ecology. With this model, several issues of general interest are discussed such as the growth of animal population, extinctions, cell growth and allometry, and the effect of environment over a population.Comment: 41 Pages, 5 figures Submitted to JT

Investigating controls on salt movement in extensional settings using finite-element modelling

Salt structures present numerous challenges for targeting reservoirs. Salt movement within the subsurface can follow complex pathways, producing deformation patterns in surrounding strata which are often difficult to decipher. Consequently, the relative role of key salt-flow drivers and geological sensitivities on salt-structure evolution are often poorly understood. To address this, we have developed 2D geomechanical models using the finite-element method to simulate salt diapir and pillow development in two extensional tectonic settings. We conducted model sensitivity analyses to examine the influence of geological parameters on field-scale salt structures and their corresponding deformation pattern. Modelled diapirs developing in thin-skinned extensional settings closely resemble published analogue experiments; however, active and passive stages of diapir growth are seldom or never reached, respectively, thus challenging existing ideas that diapir evolution is dominated by passive growth. In all modelled cases, highly strained domains bound the diapir flanks where extensive small-scale faulting and fracturing can be expected. Asymmetrical diapirs are prone to flank collapse and are observed in models with fast extension or sedimentation rates, thin roof sections or salt layers, or initially short or triangular-shaped diapirs. In modelled thick-skinned extensional settings, salt pillows and suprasalt overburden faults can be laterally offset (decoupled) from a reactivating basement fault. This decoupling increases with increased salt-layer thickness, overburden thickness, sedimentation rate and fault angle, and decreased fault slip rates. Contrary to existing consensus, overburden grounding onto the basement fault scarp does not appear to halt development of salt structures above the footwall basement block

Kansas Early Childhood Transition Task Force Tour: Preliminary Results from Community Engagement Tour

Kansas Executive Order 23-01 established the Early Childhood Transition Task Force (ECTTF) and tasked the group with holding a series of meetings across the state to generate public feedback and responses to Kansas’ current early childhood system. To better understand the current situation of early childhood efforts in the State of Kansas, the Kansas ECTTF conducted a statewide tour with virtual and in-person opportunities for participants to reflect on Kansas’ early childhood system. The participants’ responses were prompted by questions in three different categories: Needs and Barriers, Bright Spots, and State’s Efficiency in Early Child Care and Education. Participants were also asked to rate how hopeful they are that Kansas is going in the right direction in early childhood. The average hope score was high, which conveys trust and confidence from those in attendance. Based on these findings, the Task Force developed recommendations to improve Kansas’ current early childhood system and the state’s role in it

What features epitomize cohesion: development of a preliminary measure

Presently, no consensus has been reached with regards to measuring workplace cohesion. Cohesion measures often allude to abstract concepts rather than tangible features, therefore this study identified the tangible features and specific practices that epitomize cohesive workgroups. Specifically, 28 individuals were interviewed and asked to reflect upon two workgroups in which they had been employed before, only one of which was cohesive. Participants identified tangible features, practices, or characteristics that typified each of these workgroups. Content analysis uncovered 14 features of cohesion, such as shared emotional events in the past, friendly and welcoming greetings, and a feeling of pride when other people in the team excel on some task. A provisional measure of cohesion was then distilled from these items

A direct D-bar reconstruction algorithm for recovering a complex conductivity in 2-D

A direct reconstruction algorithm for complex conductivities in $W^{2,\infty}(\Omega)$, where $\Omega$ is a bounded, simply connected Lipschitz domain in $\mathbb{R}^2$, is presented. The framework is based on the uniqueness proof by Francini [Inverse Problems 20 2000], but equations relating the Dirichlet-to-Neumann to the scattering transform and the exponentially growing solutions are not present in that work, and are derived here. The algorithm constitutes the first D-bar method for the reconstruction of conductivities and permittivities in two dimensions. Reconstructions of numerically simulated chest phantoms with discontinuities at the organ boundaries are included.Comment: This is an author-created, un-copyedited version of an article accepted for publication in [insert name of journal]. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at 10.1088/0266-5611/28/9/09500

Cognitive behavioural therapy self-help intervention preferences among informal caregivers of adults with chronic kidney disease: an online cross-sectional survey

BACKGROUND: Informal caregivers (i.e. family and friends) provide essential support to people with chronic kidney disease (CKD). Many informal caregivers experience mental health problems such as anxiety and depression due to the caregiving role, and commonly have unmet psychological support needs. One potential solution is cognitive behavioural therapy (CBT) self-help interventions that are less reliant on extensive involvement of healthcare professionals, which may increase access. Within the intervention development phase of the MRC framework, the study’s primary objective was to examine informal caregivers’ self-help intervention preferences (e.g. delivery format, content). Secondary objectives were to describe the informal caregiver’s situation (e.g. type of care activities) and mental health (symptoms of depression, anxiety, and stress). METHODS: An online cross-sectional survey conducted in the United Kingdom. Informal caregivers of adults living with CKD were recruited via social media, websites, newsletters, magazine articles, a podcast episode, and paid Facebook advertisements. The survey examined: informal caregiver characteristics; care recipient characteristics; self-help intervention preferences; and informal caregiver’s mental health using the DASS-21. Data were analysed using descriptive statistics. RESULTS: Sixty-five informal caregivers participated. The majority (85%) were female, caring for a male (77%) spouse/partner (74%). Responses indicated 58% of informal caregivers were experiencing at least mild depression. In total, 48% indicated they were likely to use a CBT self-help intervention, preferring an intervention provided via internet (e.g. website) (64%), workbook (56%), or individually in-person (54%). Regarding content, interventions should cover a wide range of topics including living with CKD, support services, informal caregiver’s physical health, and diet. Overall, 48% reported a preference for a supported intervention, with support delivered in-person or via email by a trained professional at a community organisation. CONCLUSIONS: Results suggest CBT self-help interventions may be an acceptable way to provide psychological support to informal caregivers, however the study is limited by the small sample size. A wide range of intervention preferences were identified indicating a need to tailor intervention content and delivery to enhance acceptability and engagement. Results will inform development of a CBT self-help intervention for informal caregivers of people with CKD. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12882-022-03052-7

Detecting level crossings without looking at the spectrum

In many physical systems it is important to be aware of the crossings and avoided crossings which occur when eigenvalues of a physical observable are varied using an external parameter. We have discovered a powerful algebraic method of finding such crossings via a mapping to the problem of locating the roots of a polynomial in that parameter. We demonstrate our method on atoms and molecules in a magnetic field, where it has implications in the search for Feshbach resonances. In the atomic case our method allows us to point out a new class of invariants of the Breit-Rabi Hamiltonian of magnetic resonance. In the case of molecules, it enables us to find curve crossings with practically no knowledge of the corresponding Born-Oppenheimer potentials.Comment: 4 pages, new title, no figures, accepted by Phys. Rev. Let

Dark-adapted red flash ERGs in healthy adults

Purpose: The x-wave of the dark-adapted (DA) ERG to a red flash reflects DA cone function. This exploratory study of healthy adults aimed to investigate changes in the DA red ERG with flash strength and during dark adaptation to optimise visualisation and therefore quantification of the x-wave. Methods: The effect of altering red flash strength was investigated in four subjects by recording ERGs after 20 minutes dark adaptation to red flashes (0.2–2.0 cd s m-2) using skin electrodes and natural pupils. The effect of dark adaptation duration was investigated in 16 subjects during 20 minutes in the dark, by recording DA 1.5 red ERGs at 1, 2, 3, 4, 5, 10, 15 and 20 minutes. Results: For a dark adaption period of 20 minutes, the x-wave was more clearly visualised to weaker (< 0.6 cd s m-2) red flash strengths: to stronger flashes it became obscured by the b-wave. For red flashes of 1.5 cd s m-2, the x-wave was most prominent in ERGs recorded after 1–5 minutes of dark adaptation: with longer dark-adaptation, it was subsumed into the b-wave’s rising edge. Conclusions: This small study suggests that x-wave visibility in healthy subjects after 20 minutes dark adaptation is improved by using flashes weaker than around 0.6 cd s m-2; for flash strengths of 1.5 cd s m-2, x-wave visibility is enhanced by recording after only around 5 minutes of dark adaptation. No evidence was found that interim red flash ERGs affecting the dark-adapted state of the normal retina

Autocorrelations of stellar light and mass in the low-redshift Universe

The final data release of the Sloan Digital Sky Survey (SDSS) provides reliable photometry and spectroscopy for about half a million galaxies with median redshift 0.09. Here we use these data to estimate projected autocorrelation functions w_p(r_p) for the light of galaxies in the five SDSS photometric bands. Comparison with the analogous stellar mass autocorrelation, estimated in a previous paper, shows that stellar luminosity is less strongly clustered than stellar mass in all bands and on all scales. Over the full nonlinear range 10 kpc/h < r_p < 10 Mpc/h our autocorrelation estimates are extremely well represented by power laws. The parameters of the corresponding spatial functions \xi(r) = (r/r_0)^\gamma vary systematically from r_0=4.5 Mpc/h and \gamma=-1.74 for the bluest band (the u band) to r_0=5.8 Mpc/h and \gamma=-1.83 for the reddest one (the z band). These may be compared with r_0=6.1 Mpc/h and \gamma=-1.84 for the stellar mass. Ratios of w_p(r_p) between two given wavebands are proportional to the mean colour of correlated stars at projected distance r_p from a randomly chosen star. The ratio of the stellar mass and luminosity autocorrelations measures an analogous mean stellar mass-to-light ratio (M*/L). All colours get redder and all mass-to-light ratios get larger with decreasing r_p, with the amplitude of the effects decreasing strongly to redder passbands. Even for the u-band the effects are quite modest, with maximum shifts of about 0.1 in u-g and about 25% in M*/L_u. These trends provide a precise characterisation of the well-known dependence of stellar populations on environment.Comment: 6 pages, 4 figures, accepted to MNRAS; three new paragraphs added: two at the end of Sec. 2 concerning cross-correlations between different bands and possible biases due to photometry errors, and one at the end of the paper discussing marked correlation function