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This text is geared toward students who have an undergraduate degree or extensive coursework in engineering or the physical sciences and who wish to develop their understanding of the essential topics of applied mathematics. The methods covered in the chapters form the core of analysis in engineering and the physical sciences. Readers will learn the solutions, techniques, and approaches that they will use as academic researchers or industrial R&D specialists. For example, they will be able to understand the fundamentals behind the various scientific software packages that are used to solve technical problems (such as the equations describing the solid mechanics of complex structures or the fluid mechanics of short-term weather prediction and long-term climate change), which is crucial to working with such codes successfully. Detailed and numerous worked problems help to ensure a clear and well-paced introduction to applied mathematics. Computational challenge problems at the end of each chapter provide students with the opportunity for hands-on learning and help to ensure mastery of the concepts. Adaptable to one- and two-semester courses.
Acifluorfen is a non-systemic PPO-inhibiting herbicide commonly used for postemergence Palmer amaranth control in soybean, peanut, and rice across the southern United States. Concerns have been raised regarding herbicide selection pressure and particle drift, increasing the need for application practices that optimize herbicide efficacy while mitigating spray drift. Field research was conducted in 2016, 2017, and 2018 in Mississippi and Nebraska to evaluate the influence of a range of spray droplet sizes [150 μm (Fine) to 900 μm (Ultra Coarse)] using acifluorfen to create a novel Palmer amaranth management recommendation using pulse width modulation (PWM) technology. A pooled site-year generalized additive model (GAM) analysis suggested that 150 μm (Fine) droplets should be used to obtain the greatest Palmer amaranth control and dry biomass reduction. Nevertheless, GAM models indicated that only 7.2% of the variability observed in Palmer amaranth control was due to differences in spray droplet size. Therefore, location-specific GAM analyses were performed to account for geographical differences to increase the accuracy of prediction models. GAM models suggested that 250 μm (Medium) droplets optimize acifluorfen efficacy on Palmer amaranth in Dundee, MS, and 310 μm (Medium) droplets could sustain 90% of maximum weed control. Specific models for Beaver City, NE indicated that 150 μm (Fine) droplets provide maximum Palmer amaranth control, and 340 μm (Medium) droplets could maintain 90% of greatest weed control. For Robinsonville, MS, optimal Palmer amaranth control could be obtained with 370 μm (Coarse) droplets, and 90% maximum control sustained with 680 μm (Ultra Coarse) droplets. Differences in optimal droplet size across location could be a result of convoluted interactions between droplet size, weather conditions, population density, plant morphology, and soil fertility levels. Future research should adopt a holistic approach to identify and investigate the influence of environmental and application parameters to optimize droplet size recommendations.
The Canadian Resident Matching Service (CaRMS) selection process has come under scrutiny due to the increasing number of unmatched medical graduates. In response, we outline our residency program's selection process including how we have incorporated best practices and novel techniques.
We selected file reviewers and interviewers to mitigate gender bias and increase diversity. Four residents and two attending physicians rated each file using a standardized, cloud-based file review template to allow simultaneous rating. We interviewed applicants using four standardized stations with two or three interviewers per station. We used heat maps to review rating discrepancies and eliminated rating variance using Z-scores. The number of person-hours that we required to conduct our selection process was quantified and the process outcomes were described statistically and graphically.
We received between 75 and 90 CaRMS applications during each application cycle between 2017 and 2019. Our overall process required 320 person-hours annually, excluding attendance at the social events and administrative assistant duties. Our preliminary interview and rank lists were developed using weighted Z-scores and modified through an organized discussion informed by heat mapped data. The difference between the Z-scores of applicants surrounding the interview invitation threshold was 0.18-0.3 standard deviations. Interview performance significantly impacted the final rank list.
We describe a rigorous resident selection process for our emergency medicine training program which incorporated simultaneous cloud-based rating, Z-scores, and heat maps. This standardized approach could inform other programs looking to adopt a rigorous selection process while providing applicants guidance and reassurance of a fair assessment.
In turbulent flows subject to strong background rotation, the advective mechanisms of turbulence are superseded by the propagation of inertial waves, as the effects of rotation become dominant. While this mechanism has been identified experimentally (Dickinson & Long, J. Fluid Mech., vol. 126, 1983, pp. 315–333; Davidson, Staplehurst & Dalziel, J. Fluid Mech., vol. 557, 2006, pp. 135–144; Staplehurst, Davidson & Dalziel, J. Fluid Mech., vol. 598, 2008, pp. 81–105; Kolvin et al.Phys. Rev. Lett., vol. 102, 2009, 014503), the conditions of the transition between the two mechanisms are less clear. We tackle this question experimentally by tracking the turbulent front away from a solid wall where jets enter an otherwise quiescent fluid. Without background rotation, this apparatus generates a turbulent front whose displacement recovers the
law classically obtained with an oscillating grid (Dickinson & Long, Phys. Fluids, vol. 21 (10), 1978, pp. 1698–1701) and we further establish the scale independence of the associated transport mechanism. When the apparatus is rotating at a constant velocity perpendicular to the wall where fluid is injected, not only does the turbulent front become mainly transported by inertial waves, but advection itself is suppressed because of the local deficit of momentum incurred by the propagation of these waves. Scale-by-scale analysis of the displacement of the turbulent front reveals that the transition between advection and propagation is local both in space and spectrally, and takes place when the Rossby number based on the considered scale is of order unity, or equivalently, when the scale-dependent group velocity of inertial waves matched the local advection velocity.
Brominated flame retardants (BFR) are primarily used as flame retardant additives in insulating materials. These lipophilic compounds can bioaccumulate in animal tissues, leading to human exposure via food ingestion. Although their concentration in food is not yet regulated, several of these products are recognised as persistent organic pollutants; they are thought to act as endocrine disruptors. The present study aimed to characterise the occurrence of two families of BFRs (hexabromocyclododecane (HBCDD) and polybrominated diphenyl ethers (PBDE)) in hen eggs and broiler or pig meat in relation to their rearing environments. Epidemiological studies were carried out on 60 hen egg farms (34 without an open-air range, 26 free-range), 57 broiler farms (27 without an open-air range, 30 free-range) and 42 pig farms without an open-air range in France from 2013 to 2015. For each farm, composite samples from either 12 eggs, five broiler pectoral muscles or three pig tenderloins were obtained. Eight PBDE congeners and three HBCDD stereoisomers were quantified in product fat using gas chromatography–high-resolution mass spectrometry, or high-performance liquid chromatography–tandem mass spectrometry, respectively. The frequencies of PBDE detection were 28% for eggs (median concentration 0.278 ng/g fat), 72% for broiler muscle (0.392 ng/g fat) and 49% for pig muscle (0.403 ng/g fat). At least one HBCDD stereoisomer was detected in 17% of eggs (0.526 ng/g fat), 46% of broiler muscle (0.799 ng/g fat) and 36% of pig muscle (0.616 ng/g fat). Results were similar in concentration to those obtained in French surveillance surveys from 2012 to 2016. Nevertheless, the contamination of free-range eggs and broilers was found to be more frequent than that of conventional ones, suggesting that access to an open-air range could be an additional source of exposure to BFRs for animals. However, the concentration of BFRs in all products remained generally very low. No direct relationship could be established between the occurrence of BFRs in eggs and meat and the characteristics of farm buildings (age, building materials). The potential presence of BFRs in insulating materials is not likely to constitute a significant source of animal exposure as long as the animals do not have direct access to these materials.
The shape gradient is a local sensitivity function defined on the surface of an object which provides the change in a characteristic quantity, or figure of merit, associated with a perturbation to the shape of the object. The shape gradient can be used for gradient-based optimization, sensitivity analysis and tolerance calculations. However, it is generally expensive to compute from finite-difference derivatives for shapes that are described by many parameters, as is the case for typical stellarator geometry. In an accompanying work (Antonsen, Paul & Landreman J. Plasma Phys., vol. 85 (2), 2019), generalized self-adjointness relations are obtained for magnetohydrodynamic (MHD) equilibria. These describe the relation between perturbed equilibria due to changes in the rotational transform or toroidal current profiles, displacements of the plasma boundary, modifications of currents in the vacuum region or the addition of bulk forces. These are applied to efficiently compute the shape gradient of functions of MHD equilibria with an adjoint approach. In this way, the shape derivative with respect to any perturbation applied to the plasma boundary or coil shapes can be computed with only one additional MHD equilibrium solution. We demonstrate that this approach is applicable for several figures of merit of interest for stellarator configuration optimization: the magnetic well, the magnetic ripple on axis, the departure from quasisymmetry, the effective ripple in the low-collisionality
(Nemov et al.Phys. Plasmas, vol. 6 (12), 1999, pp. 4622–4632) and several finite-collisionality neoclassical quantities. Numerical verification of this method is demonstrated for the magnetic well figure of merit with the VMEC code (Hirshman & Whitson Phys. Fluids, vol. 26 (12), 1983, p. 3553) and for the magnetic ripple with modification of the ANIMEC code (Cooper et al.Comput. Phys. Commun., vol. 72 (1), 1992, pp. 1–13). Comparisons with the direct approach demonstrate that, in order to obtain agreement within several per cent, the adjoint approach provides a factor of
in computational savings.
This study examined the long-term effects of a randomized controlled trial of the Family Check-Up (FCU) intervention initiated at age 2 on inhibitory control in middle childhood and adolescent internalizing and externalizing problems. We hypothesized that the FCU would promote higher inhibitory control in middle childhood relative to the control group, which in turn would be associated with lower internalizing and externalizing symptomology at age 14. Participants were 731 families, with half (n = 367) of the families assigned to the FCU intervention. Using an intent-to-treat design, results indicate that the FCU intervention was indirectly associated with both lower internalizing and externalizing symptoms at age 14 via its effect on increased inhibitory control in middle childhood (i.e., ages 8.5–10.5). Findings highlight the potential for interventions initiated in toddlerhood to have long-term impacts on self-regulation processes, which can further reduce the risk for behavioral and emotional difficulties in adolescence.
− The role of the state as an agent of earth system governance has become more complex, contingent, and interdependent. − Although participatory and collaborative processes have contributed to more effective, equitable, and legitimate environmental governance outcomes in some instances, analyses of these processes should be situated within a broader governance perspective, which recasts questions of policy change around questions of power and justice. −The complexity and normative aspects of agency in earth system governance requires new forms of policy evaluation that account for social impacts and the ability of governance systems to adapt. − Many of the core analytical concepts in ESG–Agency scholarship, such as agency, power, authority, and accountability, remain under-theorized. In addition, some types of actors, including women, labor, non-human agents, those who work against earth system governance, and many voices from the Global South, remain largely hidden. − ESG–Agency scholars need to develop research projects and collaborations in understudied regions while also recruiting and supporting scholars in those regions to engage with this research agenda.
The climate crisis requires nations to achieve human well-being with low national levels of carbon emissions. Countries vary from one another dramatically in how effectively they convert resources into well-being, and some nations with low levels of emissions have relatively high objective and subjective well-being. We identify urgent research and policy agendas for four groups of countries with either low or high emissions and well-being indicators. Least studied are those with low well-being and high emissions. Understanding social and political barriers to switching from high-carbon to lower-carbon modes of production and consumption, and ways to overcome them, will be fundamental.
Herbicide applications performed with pulse width modulation (PWM) sprayers to deliver specific spray droplet sizes could maintain product efficacy, minimize potential off-target movement, and increase flexibility in field operations. Given the continuous expansion of herbicide-resistant Palmer amaranth populations across the southern and midwestern United States, efficacious and cost-effective means of application are needed to maximize Palmer amaranth control. Experiments were conducted in two locations in Mississippi (2016, 2017, and 2018) and one location in Nebraska (2016 and 2017) for a total of seven site-years. The objective of this study was to evaluate the influence of a range of spray droplet sizes [150 (Fine) to 900 μm (Ultra Coarse)] on lactofen and acifluorfen efficacy for Palmer amaranth control. The results of this research indicated that spray droplet size did not influence lactofen efficacy on Palmer amaranth. Palmer amaranth control and percent dry biomass reduction remained consistent with lactofen applied with aforementioned droplet size range. Therefore, larger spray droplets should be used as part of a drift mitigation approach. In contrast, acifluorfen application with 300 μm (Medium) spray droplets provided the greatest Palmer amaranth control. Although percent biomass reduction was numerically greater with 300 μm (Medium) droplets, results did not differ with respect to spray droplet size, possibly due to initial plant injury, causing weight loss, followed by regrowth. Overall, 900 μm (Ultra Coarse) droplets could be used effectively without compromising lactofen efficacy on Palmer amaranth, and 300 μm (Medium) droplets should be used to achieve maximum Palmer amaranth control with acifluorfen.
Ground-penetrating radar data acquired in the 2016/17 austral summer on Sørsdal Glacier, East Antarctica, provide evidence for meltwater lenses within porous surface ice that are conceptually similar to firn aquifers observed on the Greenland Ice Sheet and the Arctic and Alpine glaciers. These englacial water bodies are associated with a dry relict surface basin and consistent with perennial drainage into an interconnected englacial drainage system, which may explain a large englacial outburst flood observed in satellite imagery in the early 2016/17 melt season. Our observations indicate the rarely-documented presence of an englacial hydrological system in Antarctica, with implications for the storage and routing of surface meltwater. Future work should ascertain the spatial prevalence of such systems around the Antarctic coastline, and identify the degree of surface runoff redistribution and storage in the near surface, to quantify their impact on surface mass balance.
Dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD) have substantial clinical and biological overlap, with cognitive deficits typically observed in the executive and visuospatial domains. However, the neuropsychological profiles of mild cognitive impairment (MCI) associated with these disorders are not well understood.
This systematic review examined existing literature on cognition in MCI due to LB disease (MCI-LB) and PD (PD-MCI) using an electronic search of seven databases (Medline, Embase, Psychinfo, PubMed, ProQuest, Scopus, and ScienceDirect). MCI-LB results were reviewed narratively given the small number of resulting papers (n = 7). Outcome variables from PD-MCI studies (n = 13) were extracted for meta-analysis of standardised mean differences (SMD).
In MCI-LB, executive dysfunction and slowed processing speed were the most prominent impairments, while visuospatial and working memory (WM) functions were also poor. MCI-LB scored significantly lower on verbal memory tests relative to controls, but significantly higher than patients with MCI due to Alzheimer’s disease. Quantitative analysis of studies in PD-MCI showed a similar profile of impairment, with the largest deficits in visuospatial function (Benton Judgement of Line Orientation, SMD g = −2.09), executive function (Trail Making Test B, SMD g = −1.65), verbal ability (Naming Tests, SMD g = −0.140), and WM (Trail Making Test A, SMD g = −1.20). In both MCI-LB and PD-MCI, verbal and visuospatial memory retrieval was impaired, while encoding and storage appeared relatively intact.
The findings of this systematic review indicate similar neuropsychological profiles in the MCI stages of DLB and PDD. Executive impairment may at least partially explain poor performance in other domains.
Guidelines recommend empowering patients and families to remind healthcare workers (HCWs) to perform hand hygiene (HH). The effectiveness of empowerment tools for patients and their families in Southeast Asia is unknown.
We performed a prospective study in a pediatric intensive care unit (PICU) of a Vietnamese pediatric referral hospital. With family and HCW input, we developed a visual tool for families to prompt HCW HH. We used direct observation to collect baseline HH data. We then enrolled families to receive the visual tool and education on its use while continuing prospective collection of HH data. Multivariable logistic regression was used to identify independent predictors of HH in baseline and implementation periods.
In total, 2,014 baseline and 2,498 implementation-period HH opportunities were observed. During the implementation period, 73 families were enrolled. Overall, HCW HH was 46% preimplementation, which increased to 73% in the implementation period (P < .001). The lowest HH adherence in both periods occurred after HCW contact with patient surroundings: 16% at baseline increased to 24% after implementation. In multivariable analyses, the odds of HCW HH during the implementation period were significantly higher than baseline (adjusted odds ratio [aOR], 2.94; 95% confidence interval [CI], 2.54–3.41; P < .001) after adjusting for observation room, HCW type, time of observation (weekday business hours vs evening or weekend), and HH moment.
The introduction of a visual empowerment tool was associated with significant improvement in HH adherence among HCWs in a Vietnamese PICU. Future research should explore acceptability and barriers to use of similar tools in low- and middle-income settings.
American Indians experience substantial health disparities relative to the US population, including vascular brain aging. Poorer cognitive test performance has been associated with cranial magnetic resonance imaging findings in aging community populations, but no study has investigated these associations in elderly American Indians.
We examined 786 American Indians aged 64 years and older from the Cerebrovascular Disease and its Consequences in American Indians study (2010–2013). Cranial magnetic resonance images were scored for cortical and subcortical infarcts, hemorrhages, severity of white matter disease, sulcal widening, ventricle enlargement, and volumetric estimates for white matter hyperintensities (WMHs), hippocampus, and brain. Participants completed demographic, medical history, and neuropsychological assessments including testing for general cognitive functioning, verbal learning and memory, processing speed, phonemic fluency, and executive function.
Processing speed was independently associated with the presence of any infarcts, white matter disease, and hippocampal and brain volumes, independent of socioeconomic, language, education, and clinical factors. Other significant associations included general cognitive functioning with hippocampal volume. Nonsignificant, marginal associations included general cognition with WMH and brain volume; verbal memory with hippocampal volume; verbal fluency and executive function with brain volume; and processing speed with ventricle enlargement.
Brain-cognition associations found in this study of elderly American Indians are similar to those found in other racial/ethnic populations, with processing speed comprising an especially strong correlate of cerebrovascular disease. These findings may assist future efforts to define opportunities for disease prevention, to conduct research on diagnostic and normative standards, and to guide clinical evaluation of this underserved and overburdened population.
This chapter provides a brief review of missions using X-ray, gamma-ray, and neutron spectroscopy to determine the chemical composition of planetary surfaces. This chapter presents the history of planetary radiation measurements, including significant discoveries. Summary tables with links to the archived data provide a resource for readers interested in working in this field. Upcoming missions and possible future directions are described.
Neutrons, gamma rays, and X-rays are used to measure the subsurface elemental composition of Solar System bodies, providing insights into their formation and evolution. Neutrons and gamma rays are highly penetrating particles made by the steady bombardment of the regolith of airless bodies by galactic cosmic rays. Gamma rays are also made by the decay of natural radioelements. The escaping radiation can be detected in close-proximity orbits and analyzed to determine subsurface elemental composition to depths of a few decimeters. Because the radiation sensors have nearly omnidirectional response, spatial resolution depends on orbital altitude. X-ray fluorescence is induced by solar X-rays. Consequently, X-ray spectroscopy is most useful for studies of objects in the inner Solar System. Characteristic elemental X-rays are made within the uppermost ~100 micrometers of the surface. The suite of elements analyzed overlaps that of nuclear spectroscopy, providing complementary geochemical information. Because X-rays are easily collimated, relatively high spatial resolution measurements are possible. This chapter presents the fundamentals of neutron, gamma-ray, and X-ray production, transport, and detection along with an overview of the measurement principles, including modeling, analysis, and mapping methods.
Stationary cross-flow vortex N-factors were calculated over the surface of a yawed circular cone using computationally predicted and experimentally observed wavenumber distributions. Surface heat-flux data were obtained on a
half-angle circular cone to investigate the behaviour of the stationary waves at different angles of attack and Reynolds numbers at Mach 6 under quiet-flow conditions in the Boeing/AFOSR Mach-6 Quiet Tunnel at Purdue University. A wavelet analysis was conducted on the experimental surface heat-flux data to construct a spatial mapping of the local largest amplitude wavenumbers of the stationary cross-flow waves, which were between 40 and 80 per circumference. Significant axial and azimuthal variation was observed. The results from the wavelet analysis were used to inform the stability analysis. The computed integration marching directions demonstrated very good agreement with the experimentally observed paths. N-factors were first calculated by integrating the local amplification rate corresponding to the most amplified experimental wavenumbers. The calculations were repeated based on non-dimensional computationally varying wavenumber ratios, which were dimensionalized by the experimental data. The computed N-factors showed good agreement between the two techniques. N-factors were also computed using the computationally predicted most unstable wavenumbers. The results showed decreased agreement with the other two cases, suggesting that this assumption does not properly model the cross-flow transition process.
Two new species, Begonia bracteolata and Begonia keralensis, are described from the Western Ghats of India. They are placed in the newly created Begonia sect. Flocciferae, along with B. albo-coccinea Hook. and B. floccifera Bedd. Lectotypes are designated for three names within this section. Colour photoplates, illustrations and an identification key to Begonia sect. Flocciferae are also provided.