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Thermo-responsive hydrogels are a promising material for creating controllable actuators for use in micro-scale devices, since they expand and contract significantly (absorbing or expelling fluid) in response to relatively small temperature changes. Understanding such systems can be difficult because of the spatially and temporally varying properties of the gel, and the complex relationships between the fluid dynamics, elastic deformation of the gel and chemical interaction between the polymer and fluid. We address this using a poro-elastic model, considering the dynamics of a thermo-responsive spherical hydrogel after a sudden change in the temperature that should result in substantial swelling or shrinking. We focus on two model examples, with equilibrium parameters extracted from data in the literature. We find a range of qualitatively different behaviours when swelling and shrinking, including cases where swelling and shrinking happen smoothly from the edge, and other situations that result in the formation of an inwards-travelling spherical front that separates a core and shell with markedly different degrees of swelling. We then characterise when each of these scenarios is expected to occur. An approximate analytical form for the front dynamics is developed, with two levels of constant porosity, that well-approximates the numerical solutions. This system can be evolved forward in time, and is simpler to solve than the full numerics, allowing for more efficient predictions to be made, such as when deciding dosing strategies for drug-laden hydrogels.
Many graduate programs are sincerely invested in fostering diversity and increasing the number of students from underrepresented backgrounds who will contribute to our discipline. But increasing representation is only one step needed to address inequities, disparities, and injustices. Helping all students thrive, and have an equal opportunity to achieve their educational goals requires the creation of “safe spaces” in which demographic differences are understood, appreciated, and considered in larger educational systems. This chapter discusses a frequently overlooked identity characteristic that can significantly impact the graduate school experience: being a first-generation college student.
Moral injury exposure (MIE) and distress (MID) may indirectly affect the relationship between trauma exposure and alterations in autonomic regulation [assessed via high-frequency heart rate variability (hfHRV)] in civilians, but this has not been tested in prior research. We conducted two exploratory studies to examine trauma types' associations with MIE and MID among civilian medical patients (Study 1) and explore how these facets may indirectly affect the relationship between trauma type and hfHRV among civilians seeking mental health services (Study 2).
Participants recruited from a public hospital and/or community advertisements (Study 1, n = 72, 87.5% Black, 83.3% women; Study 2, n = 46, 71.7% Black, 97.8% women) completed measures assessing trauma type, MIE, and MID. In Study 1, trauma types that emerged as significant correlates of MIE and MID were entered into separate linear regression analyses. Trauma types identified were included as predictors in indirect effects models with MIE or MID as the mediator and resting hfHRV (assayed via electrocardiography) as the outcome.
Childhood sexual abuse emerged as the only significant predictor of MIE, b = 0.38, p < 0.001; childhood sexual abuse, b = 0.26, p < 0.05, and adulthood sexual assault, b = 0.23, p < 0.05 were significant predictors of MID. Participants with greater MIE and MID demonstrated lower hfHRV. Adulthood sexual assault showed an indirect effect on hfHRV through MID, B = −0.10, s.e. = 0.06, 95%CI (−0.232 to −0.005).
Moral injury was uniquely associated with sexual violence and lower hfHRV in civilians. Data highlight moral injury as a pathway through which autonomic dysregulation may emerge and its salience for trauma treatment selection.
Rising costs and challenges of in-person interviewing have prompted major surveys to consider moving online and conducting live web-based video interviews. In this paper, we evaluate video mode effects using a two-wave experimental design in which respondents were randomized to either an interviewer-administered video or interviewer-administered in-person survey wave after completing a self-administered online survey wave. This design permits testing of both within- and between-subject differences across survey modes. Our findings suggest that video interviewing is more comparable to in-person interviewing than online interviewing across multiple measures of satisficing, social desirability, and respondent satisfaction.
The adoption of dicamba-resistant cotton (Gossypium hirsutum L.) cultivars allows using dicamba to reduce weed populations across growing seasons. However, the overuse of this tool risks selecting new herbicide resistant biotypes. The objectives of this research were to determine the population trajectories of several weed species and track the frequency of glyphosate-resistant Palmer amaranth (Amaranthus palmeri S. Watson) (GR) over 8 years in dicamba-resistant cotton. An experiment was established in North Carolina in 2011, and during the first four years, different herbicide programs were applied. These programs included postemergence applications of glyphosate, alone or with dicamba, with or without residual herbicides. During the last 4 years, all programs received glyphosate plus dicamba. Biennial rotations of postemergence applications of glyphosate only and glyphosate plus dicamba postemergence with and without preemergence herbicides were also included. Sequential applications of glyphosate plus dicamba were applied to the entire test area for the final 4 years of the study. No herbicide program was entirely successful in controlling the weed community. Weed population trajectories were different according to species and herbicide program, creating all possible outcomes; some increased, other decreased, and others remained stable. Density of resistant A. palmeri increased during the first 4 years with glyphosate only programs (up to 11739 plants per m2) and decreased a 96% during the final 4 years when glyphosate plus dicamba was implemented. This species had a strong influence on population levels of other weed species in the community. Goosegras [Eleusine indica (L.) Gaertn.] was not affected by A. palmeri population levels and even increased its density in some herbicide programs, indicating that not only herbicide resistance but also reproductive rates and competitive dynamics are critical for determining weed population trajectories under intensive herbicide-based control programs. Frequency of GR reached a maximum of 62% after 4 years and maintained those levels until the end of the experiment.
Kounis syndrome is the concurrence of acute coronary syndrome or coronary vasospasm with conditions associated with the release of inflammatory cytokines through mast cell activation in the setting of allergic or anaphylactic reactions. Many identified triggers have been identified in paediatric patients including exposures, drugs, and immunisations; however, to our knowledge this is the first case report of Kounis syndrome linked to immunotherapy. We present a case of a 9-year-old with seasonal allergies presenting with clinical symptoms of Kounis syndrome following her weekly subcutaneous injection of allergens. Clinicians need a high index of suspicion for Kounis syndrome in patients who develop systemic signs of anaphylaxis with clinical, laboratory, electrocardiographic, and echocardiographic findings of acute coronary syndrome to help direct therapy and improve outcomes.
Palmer amaranth (Amaranthus palmeri S. Watson) is one of the most problematic weeds in many cropping systems in the midsouthern United States because of its multiple weedy traits and its propensity to evolve resistance to many herbicides with different mechanisms of action. In Arkansas, A. palmeri has evolved metabolic resistance to S-metolachlor, compromising the effectiveness of an important weed management tool. Greenhouse studies were conducted to evaluate the differential response of A. palmeri accessions from three states (Arkansas, Mississippi, and Tennessee) to (1) assess the occurrence of resistance to S-metolachlor among A. palmeri populations, (2) evaluate the resistance level in selected accessions and their resistant progeny, (3) and determine the susceptibility of most resistant accessions to other soil-applied herbicides. Seeds were collected from 168 crop fields between 2017 and 2019. One hundred seeds per accession were planted in silt loam soil without herbicide for >20 yr and sprayed with the labeled rate of S-metolachlor (1,120 g ai ha−1). Six accessions (four from Arkansas and two from Mississippi) were classified resistant to S-metolachlor. The effective doses (LD50) to control the parent accessions ranged between 73 and 443 g ha−1, and those of F1 progeny of survivors were 73 to 577 g ha−1. The resistance level was generally greater among progeny of surviving plants than among resistant field populations. The resistant field populations required 2.2 to 7.0 times more S-metolachlor to reduce seedling emergence 50%, while the F1 of survivors needed up to 9.2 times more herbicide to reduce emergence 50% compared with the susceptible standard.
Quantitative methods have been used to: (1) better predict civil conflict onset; and (2) understand causal mechanisms to inform policy intervention and theory. However, an exploration of individual conflict onset cases illustrates great variation in the characteristics describing the outbreak of civil war, suggesting that there is not one single set of factors that lead to intrastate war. In this article, we use descriptive statistics to explore persistent clusters in the drivers of civil war onset, finding evidence that some arrangements of structural drivers cluster robustly across multiple model specifications (such as young, poorly developed states with anocratic regimes). Additionally, we find that approximately one-fifth of onset cases cannot be neatly clustered across models, suggesting that these cases are difficult to predict and multiple methods for understanding civil conflict onset (and state failure more generally) may be necessary.
There are concerns that the South African higher education system is not producing sufficient graduates to meet national needs in respect of economic and social development. Systemic reform such as strengthening the undergraduate teaching and research relationship, which is inextricably tied to curriculum structure, is necessary to meet the goals of equity and development and enhancing graduate quality. This can potentially widen the pipeline into postgraduate studies and produce the next generation of academics. The main argument of this chapter is the need to profoundly change the manner in which teaching is structured in South Africa, in order to shift the prevailing culture of undergraduate students as receivers to one in which they are inquirers. This requires pedagogies that enable inquiry-led learning to be developed, to actively engage students in the research process and for them to make the linkage to their discipline-specific practice. An increased focus on building an undergraduate research culture through pedagogical reforms is still needed.
Shade coffee is a well-studied cultivation strategy that creates habitat for tropical birds while also maintaining agricultural yield. Although there is a general consensus that shade coffee is more “bird-friendly” than a sun coffee monoculture, little work has investigated the effects of specific shade tree species on insectivorous bird diversity. This study involved avian foraging observations, mist-netting data, temperature loggers, and arthropod sampling to investigate bottom-up effects of two shade tree taxa - native Cordia sp. and introduced Grevillea robusta - on insectivorous bird communities in central Kenya. Results indicate that foliage-dwelling arthropod abundance, and the richness and overall abundance of foraging birds were all higher on Cordia than on Grevillea. Furthermore, multivariate analyses of the bird community indicate a significant difference in community composition between the canopies of the two tree species, though the communities of birds using the coffee understorey under these shade trees were similar. In addition, both shade trees buffered temperatures in coffee, and temperatures under Cordia were marginally cooler than under Grevillea. These results suggest that native Cordia trees on East African shade coffee farms may be better at mitigating habitat loss and attracting insectivorous birds that could promote ecosystem services. Identifying differences in prey abundance and preferences in bird foraging behaviour not only fills basic gaps in our understanding of the ecology of East African coffee farms, it also aids in developing region-specific information to optimize functional diversity, ecosystem services, and the conservation of birds in agricultural landscapes.
We examine temporal and spatial variation in morphology of the ammonoid cephalopod Discoscaphites iris using a large dataset from multiple localities in the Late Cretaceous (Maastrichtian) of the U.S. Gulf and Atlantic Coastal Plains, spanning a distance of 2000 km along the paleoshoreline. Our results suggest that the fossil record of D. iris is consistent with no within-species net accumulation of phyletic evolutionary change across morphological traits or the lifetime of this species. Correlations between some traits and paleoenvironmental conditions as well as changes in the coefficient of variation may support limited population-scale ecophenotypic plasticity; however, where stratigraphic data are available, no directional changes in morphology occur before the Cretaceous/Paleogene (K/Pg) boundary. This is consistent with models of “dynamic” evolutionary stasis. Combined with knowledge of life-history traits and paleoecology of scaphitid ammonoids, specifically a short planktonic phase after hatching followed by transition to a nektobenthic adult stage, these data suggest that scaphitids had significant potential for rapid morphological change in conjunction with limited dispersal capacity. It is therefore likely that evolutionary mode in the Scaphitidae (and potentially across the broader ammonoid clade) follows a model of cladogenesis wherein a dynamic morphological stasis is periodically interrupted by more substantial evolutionary change at speciation events. Finally, the lack of temporal changes in our data suggest that global environmental changes had a limited effect on the morphology of ammonoid faunas during the latest Cretaceous.
To describe the genomic analysis and epidemiologic response related to a slow and prolonged methicillin-resistant Staphylococcus aureus (MRSA) outbreak.
Prospective observational study.
Neonatal intensive care unit (NICU).
We conducted an epidemiologic investigation of a NICU MRSA outbreak involving serial baby and staff screening to identify opportunities for decolonization. Whole-genome sequencing was performed on MRSA isolates.
A NICU with excellent hand hygiene compliance and longstanding minimal healthcare-associated infections experienced an MRSA outbreak involving 15 babies and 6 healthcare personnel (HCP). In total, 12 cases occurred slowly over a 1-year period (mean, 30.7 days apart) followed by 3 additional cases 7 months later. Multiple progressive infection prevention interventions were implemented, including contact precautions and cohorting of MRSA-positive babies, hand hygiene observers, enhanced environmental cleaning, screening of babies and staff, and decolonization of carriers. Only decolonization of HCP found to be persistent carriers of MRSA was successful in stopping transmission and ending the outbreak. Genomic analyses identified bidirectional transmission between babies and HCP during the outbreak.
In comparison to fast outbreaks, outbreaks that are “slow and sustained” may be more common to units with strong existing infection prevention practices such that a series of breaches have to align to result in a case. We identified a slow outbreak that persisted among staff and babies and was only stopped by identifying and decolonizing persistent MRSA carriage among staff. A repeated decolonization regimen was successful in allowing previously persistent carriers to safely continue work duties.
Redox flow batteries (RFBs) are an emerging electrochemical technology envisioned towards storage of renewable energy. A promising sub-class of RFBs utilizes single-flow membraneless architectures in an effort to minimize system cost and complexity. To support multiple functions, including reactant separation and fast reactant transport to electrode surfaces, electrolyte flow must be carefully designed and optimized. In this work, we propose adding a secondary channel adjacent to a permeable battery electrode, solving for the flow field and analysing the effects on the reactant concentration boundary layer at the electrode. We find that an adjacent channel with gradually changing thickness leads to a desired nearly uniform flow through the electrode to the adjacent channel. Consequently, the thickness of the concentration boundary layer is significantly reduced, increasing reactant transport to the electrode surface to 140% of the rate of a battery with a constant width adjacent channel, and 350% of the rate with no adjacent channel. Overall, this theory provides insight into the important role of flow physics for this promising sub-class of flow batteries, and can pave the way to improved energy efficiency of such flow batteries.
Background:Candida auris is an emerging multidrug-resistant yeast that is transmitted in healthcare facilities and is associated with substantial morbidity and mortality. Environmental contamination is suspected to play an important role in transmission but additional information is needed to inform environmental cleaning recommendations to prevent spread. Methods: We conducted a multiregional (Chicago, IL; Irvine, CA) prospective study of environmental contamination associated with C. auris colonization of patients and residents of 4 long-term care facilities and 1 acute-care hospital. Participants were identified by screening or clinical cultures. Samples were collected from participants’ body sites (eg, nares, axillae, inguinal creases, palms and fingertips, and perianal skin) and their environment before room cleaning. Daily room cleaning and disinfection by facility environmental service workers was followed by targeted cleaning of high-touch surfaces by research staff using hydrogen peroxide wipes (see EPA-approved product for C. auris, List P). Samples were collected immediately after cleaning from high-touch surfaces and repeated at 4-hour intervals up to 12 hours. A pilot phase (n = 12 patients) was conducted to identify the value of testing specific high-touch surfaces to assess environmental contamination. High-yield surfaces were included in the full evaluation phase (n = 20 patients) (Fig. 1). Samples were submitted for semiquantitative culture of C. auris and other multidrug-resistant organisms (MDROs) including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended-spectrum β-lactamase–producing Enterobacterales (ESBLs), and carbapenem-resistant Enterobacterales (CRE). Times to room surface contamination with C. auris and other MDROs after effective cleaning were analyzed. Results:Candida auris colonization was most frequently detected in the nares (72%) and palms and fingertips (72%). Cocolonization of body sites with other MDROs was common (Fig. 2). Surfaces located close to the patient were commonly recontaminated with C. auris by 4 hours after cleaning, including the overbed table (24%), bed handrail (24%), and TV remote or call button (19%). Environmental cocontamination was more common with resistant gram-positive organisms (MRSA and, VRE) than resistant gram-negative organisms (Fig. 3). C. auris was rarely detected on surfaces located outside a patient’s room (1 of 120 swabs; <1%). Conclusions: Environmental surfaces near C. auris–colonized patients were rapidly recontaminated after cleaning and disinfection. Cocolonization of skin and environment with other MDROs was common, with resistant gram-positive organisms predominating over gram-negative organisms on environmental surfaces. Limitations include lack of organism sequencing or typing to confirm environmental contamination was from the room resident. Rapid recontamination of environmental surfaces after manual cleaning and disinfection suggests that alternate mitigation strategies should be evaluated.
The goal for many PhD students in archaeology is tenure-track employment. Students primarily receive their training by tenure-track or tenured professors, and they are often tacitly expected—or explicitly encouraged—to follow in the footsteps of their advisor. However, the career trajectories that current and recent PhD students follow may hold little resemblance to the ones experienced by their advisors. To understand these different paths and to provide information for current PhD students considering pursuing a career in academia, we surveyed 438 archaeologists holding tenured or tenure-track positions in the United States. The survey, recorded in 2019, posed a variety of questions regarding the personal experiences of individual professors. The results are binned by the decade in which the respondent graduated. Evident patterns are discussed in terms of change over time. The resulting portraits of academic pathways through the past five decades indicate that although broad commonalities exist in the qualifications of early career academics, there is no singular pathway to obtaining tenure-track employment. We highlight the commonalities revealed in our survey to provide a set of general qualifications that might provide a baseline set of skills and experiences for an archaeologist seeking a tenure-track job in the United States.
Delayed cerebral ischemia (DCI) is a complication of aneurysmal subarachnoid hemorrhage (aSAH) and is associated with significant morbidity and mortality. There is little high-quality evidence available to guide the management of DCI. The Canadian Neurosurgery Research Collaborative (CNRC) is comprised of resident physicians who are positioned to capture national, multi-site data. The objective of this study was to evaluate practice patterns of Canadian physicians regarding the management of aSAH and DCI.
We performed a cross-sectional survey of Canadian neurosurgeons, intensivists, and neurologists who manage aSAH. A 19-question electronic survey (Survey Monkey) was developed and validated by the CNRC following a DCI-related literature review (PubMed, Embase). The survey was distributed to members of the Canadian Neurosurgical Society and to Canadian members of the Neurocritical Care Society. Responses were analyzed using quantitative and qualitative methods.
The response rate was 129/340 (38%). Agreement among respondents was limited to the need for intensive care unit admission, use of clinical and radiographic monitoring, and prophylaxis for the prevention of DCI. Several inconsistencies were identified. Indications for starting hyperdynamic therapy varied. There was discrepancy in the proportion of patients who felt to require IV milrinone, IA vasodilators, or physical angioplasty for treatment of DCI. Most respondents reported their facility does not utilize a standardized definition for DCI.
DCI is an important clinical entity for which no homogeneity and standardization exists in management among Canadian practitioners. The CNRC calls for the development of national standards in the definition, identification, and treatment of DCI.
This chapter provides theoretical foundations for the Prioritarianism in Practice volume, by clarifying the features of prioritarian social welfare functions (SWFs). A prioritarian SWF sums up individuals’ well-being numbers plugged into a strictly increasing and strictly increasing transformation function. Prioritarian SWFs, like the utilitarian SWF, fall within the “generalized-utilitarian” class of SWFs. Generalized-utilitarian SWFs are additive and, hence, especially tractable for purposes of policy analysis. The chapter reviews the axiomatic properties of generalized-utilitarian SWFs and, specifically, of prioritarian SWFs. Prioritarianism satisfies the Pigou-Dalton axiom (a pure, gap-diminishing transfer of well-being from a better-off to a worse-off person is an ethical improvement), while utilitarianism does not. Pigou-Dalton is the axiomatic expression of the fact that a prioritarian SWF gives extra weight (priority) to well-being changes affecting worse-off individuals. The chapter also discusses the informational requirements of prioritarian SWFs (as regards interpersonal well-being comparisons). It reviews the various methodologies for applying a prioritarian SWF under uncertainty. And it describes the two main subfamilies of prioritarian SWFs, namely Atkinson and Kolm-Pollak SWFs.