The Digital Revolution to Come: Photogrammetry in Archaeological Practice

The three-dimensional (3D) revolution promised to transform archaeological practice. Of the technologies that contribute to the proliferation of 3D data, photogrammetry facilitates the rapid and inexpensive digitization of complex subjects in both field and lab settings. It finds additional use as a tool for public outreach, where it engages audiences ranging from source communities to artifact collectors. But what has photogrammetry’s function been in advancing archaeological analysis? Drawing on our previous work, we review recent applications to understand the role of photogrammetry for contemporary archaeologists. Although photogrammetry is widely used as a visual aid, its analytical potential remains underdeveloped. Considering various scales of inquiry—graduating from objects to landscapes—we address how the technology fits within and expands existing documentation and data visualization routines, while evaluating the opportunity it presents for addressing archaeological questions and problems in innovative ways. We advance an agenda advocating that archaeologists move from proof-of concept papers toward greater integration of photogrammetry with research

Realistic boundary conditions for stochastic simulations of reaction-diffusion processes

Many cellular and subcellular biological processes can be described in terms of diffusing and chemically reacting species (e.g. enzymes). Such reaction-diffusion processes can be mathematically modelled using either deterministic partial-differential equations or stochastic simulation algorithms. The latter provide a more detailed and precise picture, and several stochastic simulation algorithms have been proposed in recent years. Such models typically give the same description of the reaction-diffusion processes far from the boundary of the simulated domain, but the behaviour close to a reactive boundary (e.g. a membrane with receptors) is unfortunately model-dependent. In this paper, we study four different approaches to stochastic modelling of reaction-diffusion problems and show the correct choice of the boundary condition for each model. The reactive boundary is treated as partially reflective, which means that some molecules hitting the boundary are adsorbed (e.g. bound to the receptor) and some molecules are reflected. The probability that the molecule is adsorbed rather than reflected depends on the reactivity of the boundary (e.g. on the rate constant of the adsorbing chemical reaction and on the number of available receptors), and on the stochastic model used. This dependence is derived for each model.Comment: 24 pages, submitted to Physical Biolog

Observational Constraints on the Dependence of Radio-Quiet Quasar X-ray Emission on Black Hole Mass and Accretion Rate

In this work we use a sample of 318 radio-quiet quasars (RQQ) to investigate the dependence of the ratio of optical/UV flux to X-ray flux, alpha_ox, and the X-ray photon index, Gamma_X, on black hole mass, UV luminosity relative to Eddington, and X-ray luminosity relative to Eddington. Our sample is drawn from the SDSS, with X-ray data from ROSAT and Chandra, and optical data mostly from the SDSS; 153 of these sources have estimates of Gamma_X from Chandra. We estimate M_BH using standard estimates derived from the Hbeta, Mg II, and C IV broad emission lines. Our sample spans a broad range in black hole mass (10^6 < M_BH / M_Sun < 10^10) and redshift (z < 4.8). We find that alpha_ox increases with increasing M_BH and L_UV / L_Edd, and decreases with increasing L_X / L_Edd. In addition, we confirm the correlation seen in previous studies between Gamma_X and M_BH and both L_UV / L_Edd and L_X / L_Edd; however, we also find evidence that the dependence of Gamma_X of these quantities is not monotonic, changing sign at M_BH ~ 3 x 10^8 M_Sun. We argue that the alpha_ox correlations imply that the fraction of bolometric luminosity emitted by the accretion disk, as compared to the corona, increases with increasing accretion rate relative to Eddington. In addition, we argue that the Gamma_X trends are caused by a dependence of X-ray spectral index on accretion rate. We discuss our results within the context of accretion models with comptonizing corona, and discuss the implications of the alpha_ox correlations for quasar feedback. To date, this is the largest study of the dependence of RQQ X-ray parameters on black hole mass and related quantities, and the first to attempt to correct for the large statistical uncertainty in the broad line mass estimates.Comment: Accepted by ApJ, 23 pages, 15 figures, emulateapj styl

A qualitative analysis of UK wetland visitor centres as a health resource

The health benefits associated with spending time in natural environments have been highlighted during the COVID-19 pandemic. Lockdowns and restrictions to safeguard public health have exacerbated the pre-existing mental health crisis and rise of non-communicable diseases. Thus, the importance of nature as a health resource has been elevated, hastening calls for a better understanding of how health benefits might differ across user groups and nature provisions. In this regard, urban green spaces have become the greatest research focus; however, blue spaces, especially inland freshwater (e.g., wetlands), remain less studied. First-hand user experiences are also under-represented. This exploratory study examines the motivations and benefits of active wetland centre users in the UK, both during and after visits. Responses to three open-ended questions were collated online from 385 participants, and a qualitative content analysis was conducted based on an existing taxonomy from users of urban green spaces. The results showed strong motivations to visit due to the biodiversity at the site (mainly the birdlife), while less tangible nature (e.g., fresh air) and amenities were also important. In contrast to other studies on natural environments, physical activity was a less influential motivation. Salient derived effects included positive and intensely positive emotions, relaxation and mental restoration. After visits to wetland centres, feelings of vitality and satisfaction were the most prominent effects that emerged. For decision-makers looking to leverage inland blue spaces for public health benefit, our results highlight the broad range and relative prominence of the reasons for use and the associated perceived health benefits derived by users of UK wetland centres. They highlight how biodiversity, abiotic nature and good amenities are important qualities to consider when planning, managing and encouraging people to use natural environments for health benefit, qualities that may also provide important environmental co-benefits

Pre-distortion adaptive optics for optical feeder links: simulations and performance analyses

Optical feeder links offer immense utility in meeting future communication demands—however, atmospheric turbulence limits their performance. This work targets this challenge through analyses of a bidirectional free-space optical communication (FSOC) link that incorporates pre-distortion adaptive optics (AO) between the next-generation optical ground station at the German Aerospace Center (DLR) Oberpfaffenhofen and the laser communications terminal on Alphasat—a satellite in geostationary orbit (GEO). The analyses are performed via end-to-end Monte Carlo simulations that provide realistic performance estimates of the bidirectional FSOC link for a GEO feeder link scenario. We find that applying pre-distortion AO reduces the total uplink losses of the bidirectional FSOC link by up to 10 dB and lessens the scintillation at the GEO satellite by an order of magnitude. Moreover, applying pre-distortion AO eases the link budget requirements needed for maintaining 99.9% link uptime by as much as 20-40 dB, while its use with a laser guide star shows an additional performance improvement of up to 8 dB. These findings demonstrate the desirability and feasibility of utilizing pre-distortion AO for the realization of optical feeder links

Insights into the influence of solvent polarity on the crystallization of poly(ethylene oxide) spin-coated thin films via in situ grazing incidence wide-angle X-ray scattering

Controlling polymer thin-film morphology and crystallinity is crucial for a wide range of applications, particularly in thin-film organic electronic devices. In this work, the crystallization behavior of a model polymer, poly(ethylene oxide) (PEO), during spin-coating is studied. PEO films were spun-cast from solvents possessing different polarities (chloroform, THF, and methanol) and probed via in situ grazing incidence wide-angle X-ray scattering. The crystallization behavior was found to follow the solvent polarity order (where chloroform chloroform > methanol). When spun-cast from nonpolar chloroform, crystallization largely followed Avrami kinetics, resulting in the formation of morphologies comprising large spherulites. PEO solutions cast from more polar solvents (THF and methanol) do not form well-defined highly crystalline morphologies and are largely amorphous with the presence of small crystalline regions. The difference in morphological development of PEO spun-cast from polar solvents is attributed to clustering phenomena that inhibit polymer crystallization. This work highlights the importance of considering individual components of polymer solubility, rather than simple total solubility, when designing processing routes for the generation of morphologies with optimum crystallinities or morphologies

Wetlands for wellbeing: piloting a nature-based health intervention for the management of anxiety and depression

Nature-based health interventions (NBIs) for the treatment of poor mental health are becoming increasingly common, yet evidence to support their effectiveness is lacking. We conduct a pilot study of a six-week intervention, aiming to engage individuals with wetland nature for the treatment of anxiety and/or depression. We employed a mixed methods design, using questionnaires, focus groups and semi-structured interviews to evaluate the intervention from the perspective of participants (n = 16) and healthcare professionals (n = 2). Results demonstrate significant improvements in mental health across a range of indicators, including mental wellbeing (Warwick and Edinburgh Mental Wellbeing Scale), anxiety (Generalised Anxiety Disorder-7), stress (Perceived Stress Scale) and emotional wellbeing (Positive and Negative Affect Schedule). Participants and healthcare professionals cited additional outcomes including improved physical health and reduced social isolation. The wetland site provided a sense of escape from participants’ everyday environments, facilitating relaxation and reductions in stress. Wetland staff knowledge of the natural world, transportation and group organisation also played a considerable role in the intervention’s success. These aspects should be considered in future and existing NBIs to maximise benefits to participants. We propose NBIs based in wetlands are an effective therapy option for individuals diagnosed with anxiety and/or depression

What should be included in case report forms? Development and application of novel methods to inform surgical study design:a mixed methods case study in parastomal hernia prevention

OBJECTIVES: To describe the development and application of methods to optimise the design of case report forms (CRFs) for clinical studies evaluating surgical procedures, illustrated with an example of abdominal stoma formation. DESIGN: (1) Literature reviews, to identify reported variations in surgical components of stoma formation, were supplemented by (2) intraoperative qualitative research (observations, videos and interviews), to identify unreported variations used in practice to generate (3) a ‘long list’ of items, which were rationalised using (4) consensus methods, providing a pragmatic list of CRF items to be captured in the Cohort study to Investigate the Prevention of parastomal HERnias (CIPHER) study. SETTING: Two secondary care surgical centres in England. PARTICIPANTS: Patients undergoing stoma formation, surgeons undertaking stoma formation and stoma nurses. OUTCOME MEASURES: Successful identification of key CRF items to be captured in the CIPHER study. RESULTS: 59 data items relating to stoma formation were identified and categorised within six themes: (1) surgical approach to stoma formation; (2) trephine formation; (3) reinforcing the stoma trephine with mesh; (4) use of the stoma as a specimen extraction site; (5) closure of other wounds during the procedure; and (6) spouting the stoma. CONCLUSIONS: This study used multimodal data collection to understand and capture the technical variations in stoma formation and design bespoke CRFs for a multicentre cohort study. The CIPHER study will use the CRFs to examine associations between the technical variations in stoma formation and risks of developing a parastomal hernia. TRIAL REGISTRATION NUMBER: ISRCTN17573805