Fractional differential equations are becoming increasingly used as a powerful modelling approach for understanding the many aspects of nonlocality and spatial heterogeneity. However, the numerical ...approximation of these models is demanding and imposes a number of computational constraints. In this paper, we introduce Fourier spectral methods as an attractive and easy-to-code alternative for the integration of fractional-in-space reaction-diffusion equations described by the fractional Laplacian in bounded rectangular domains of
R
n
. The main advantages of the proposed schemes is that they yield a fully diagonal representation of the fractional operator, with increased accuracy and efficiency when compared to low-order counterparts, and a completely straightforward extension to two and three spatial dimensions. Our approach is illustrated by solving several problems of practical interest, including the fractional Allen–Cahn, FitzHugh–Nagumo and Gray–Scott models, together with an analysis of the properties of these systems in terms of the fractional power of the underlying Laplacian operator.
For some decades now, the practices of economic and community development have increasingly intertwined. This has largely involved a rebalancing of the economic and community portions of the mix to ...give increasing prominence to the community side of the ledger. In their decade-and-a-half-old article, Rethinking Community Economic Development, Shaffer, Deller, and Marcouiller (2006) illustrated this in their classification of successive waves of dominant community economic development (CED) theory and practice: export base, business retention and expansion, collaboration and partnership driven, and cluster development. Shanna Ratner’s 2020 book Wealth Creation: A New Framework for Rural Economic and Community Development comes from one of the leading developers and practitioners of a fifth-wave approach that is beginning to lay a legitimate claim to the respect of academics, professionals, and community members alike. In 158 pages, Ratner’s slim and accessible volume does an admirable job of summarizing a synthetic approach that is both informed by theory and steeped in decades of participant-observation and learning-by-doing. The author, often addressing the reader as “you,” as if in the training workshops she has frequently provided, explicitly aims at writing for those with few degrees of separation from CED practice: “policy makers, practitioners in economic and community development, teachers, students including undergraduates, I would specify, financers and funders…” (p. viii). . . .
Fractional differential equations are becoming increasingly used as a modelling tool for processes associated with anomalous diffusion or spatial heterogeneity. However, the presence of a fractional ...differential operator causes memory (time fractional) or nonlocality (space fractional) issues that impose a number of computational constraints. In this paper we develop efficient, scalable techniques for solving fractional-in-space reaction diffusion equations using the finite element method on both structured and unstructured grids via robust techniques for computing the fractional power of a matrix times a vector. Our approach is show-cased by solving the fractional Fisher and fractional Allen--Cahn reaction-diffusion equations in two and three spatial dimensions, and analyzing the speed of the traveling wave and size of the interface in terms of the fractional power of the underlying Laplacian operator.
Impulse propagation in biological tissues is known to be modulated by structural heterogeneity. In cardiac muscle, improved understanding on how this heterogeneity influences electrical spread is key ...to advancing our interpretation of dispersion of repolarization. We propose fractional diffusion models as a novel mathematical description of structurally heterogeneous excitable media, as a means of representing the modulation of the total electric field by the secondary electrical sources associated with tissue inhomogeneities. Our results, analysed against in vivo human recordings and experimental data of different animal species, indicate that structural heterogeneity underlies relevant characteristics of cardiac electrical propagation at tissue level. These include conduction effects on action potential (AP) morphology, the shortening of AP duration along the activation pathway and the progressive modulation by premature beats of spatial patterns of dispersion of repolarization. The proposed approach may also have important implications in other research fields involving excitable complex media.
This paper reviews the latest evidence provided by epidemiological studies and quantitative microbial risk assessments (QMRAs) of infection risk from recreational water use. Studies for review were ...selected following a PubMed search for articles published between January 2010 and April 2014. Epidemiological studies show a generally elevated risk of gastrointestinal illness in bathers compared to non-bathers but often no clear association with water quality as measured by faecal indicator bacteria; this is especially true where study sites are impacted by non-point source pollution. Evidence from QMRAs support the lack of a consistent water quality association for non-point source-impacted beaches. It is suggested that source attribution, through quantified microbial source apportionment, linked with appropriate use of microbial source tracking methods should be employed as an integral part of future epidemiological surveys.
The family Lauraceae possesses ca. 50 genera and 2,500-3,000 species that are distributed in the pantropics. Only half of the genera of the family were represented in previously published plastome ...phylogenies because of the difficulty of obtaining research materials. Plastomes of Hypodaphnideae and the Mezilaurus group, two lineages with unusual phylogenetic positions, have not been previously reported and thus limit our full understanding on the plastome evolution of the family. Herbariomics, promoted by next generation sequencing technology, can make full use of herbarium specimens, and provides opportunities to fill the sampling gap.
In this study, we sequenced five new plastomes (including four genera which are reported for the first time, viz. Chlorocardium, Hypodaphnis, Licaria and Sextonia) from herbarium specimens using genome skimming to conduct a comprehensive analysis of plastome evolution of Lauraceae as a means of sampling representatives of all major clades of the family. We identified and recognized six types of plastomes and revealed that at least two independent loss events at the IR-LSC boundary and an independent expansion of SSC occurred in the plastome evolution of the family. Hypodaphnis possesses the ancestral type of Lauraceae with trnI-CAU, rpl23 and rpl2 duplicated in the IR regions (Type-I). The Mezilaurus group shares the same plastome structure with the core Lauraceae group in the loss of trnI-CAU, rpl23 and rpl2 in the IRa region (Type-III). Two new types were identified in the Ocotea group: (1) the insertion of trnI-CAU between trnL-UAG and ccsA in the SSC region of Licaria capitata and Ocotea bracteosa (Type-IV), and (2) trnI-CAU and pseudogenizated rpl23 inserted in the same region of Nectandra angustifolia (Type-V). Our phylogeny suggests that Lauraceae are divided into nine major clades largely in accordance with the plastome types. The Hypodaphnideae are the earliest diverged lineage supported by both robust phylogeny and the ancestral plastome type. The monophyletic Mezilaurus group is sister to the core Lauraceae.
By using herbariomics, we built a more complete picture of plastome evolution and phylogeny of the family, thus providing a convincing case for further use of herbariomics in phylogenetic studies of the Lauraceae.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Whilst mobility has long been a key theme within African archaeology, its study has usually focussed on cases of far-ranging nomadism, particularly amongst ‘hunter-gatherer’ pastoralist populations. ...Conversely, changes in the form and distribution of sedentary settlement have most commonly been studied across wide spatio-temporal ranges that do not consider the role of mobile livelihood practices at scales appreciable to the people who actually performed them. This paper seeks to rectify this scholarly lacuna through the practical application of the concept of ‘shifting sedentism’ amongst the communities of Kenya’s northern Elgeyo Escarpment. Combining archaeological/contemporary household survey data with local oral histories, this paper explores how the incremental movement of individual housing compounds has contributed to the gradual shift of Marakwet settlement across the landscape over the past two centuries. Shifting patterns of residence will be linked with broader trends in mobile livelihood practice that extend across the surrounding landscape and run through multiple generations. These practices have themselves adeptly incorporated many major changes to community lifeways—including the introduction of new crops, Christian missionisation, road building and the growth of small commercial centres. Such practices embody a particularly flexible approach to socio-cultural continuity, in which situational mobility has been vital in ensuring the overarching resilience of these communities and the rugged landscape they call home. Fine-grained and multi-disciplinary approaches are key to the recognition of mobility’s importance within such otherwise sedentary contexts, and it is hoped this particular study will inspire further such efforts across the continent.
The propensity of nanoparticles to aggregate in aqueous media hinders their effective use in biomedical applications. Gold nanorods (GNRs) have been investigated as therapeutics, imaging agents, and ...diagnostics. We report that chemically generated gold nanorods rapidly aggregate in biologically relevant media. Depositing polyelectrolyte multilayers on gold nanorods enhanced the stability of these nanoparticles for at least up to 4 weeks. Dispersions of polyelectrolyte (PE)-gold nanorod assemblies (PE−GNRs) demonstrate a stable Arrhenius-like photothermal response, which was exploited for the hyperthermic ablation of prostate cancer cells in vitro. Subtoxic concentrations of PE−GNR assemblies were also employed for delivering exogenous plasmid DNA to prostate cancer cells. PE−GNRs based on a cationic polyelectrolyte recently synthesized in our laboratory demonstrated higher transfection efficacy and lower cytotoxicity compared to those based on polyethyleneimine, a current standard for polymer-mediated gene delivery. Our results indicate that judicious engineering of biocompatible polyelectrolytes leads to multifunctional gold nanorod-based assemblies that combine high stability and low cytotoxicity with photothermal ablation, gene delivery, and optical imaging capabilities on a single platform.
Abstract Objectives To determine pre-operative risk factors for post-tonsillectomy secondary hemorrhage in children, and quantify the magnitude of their risk. Materials and Methods Retrospective ...case-control study of all pediatric tonsillectomy patients experiencing post-operative bleeding from 2005-2010 in a community practice consisting of three fellowship-trained pediatric otolaryngologists were identified. The 91 cases were matched with 151 controls that underwent tonsillectomy by the same surgeon on the same day as each identified case. All charts were reviewed, and 41 pre-operative variables were extracted and statistically analyzed with contingency and regression analysis to calculate significance and odds ratios. Results Three significant predictors of post-operative bleeding were identified. Performing a tonsillectomy on a child with recurrent tonsillitis (vs. other indications) increased the risk of post-operative hemorrhage by 4.5 times (p < 0.0001, 95% confidence intervals 2.41-8.38). Performing a tonsillectomy on a child with attention deficit hyperactivity disorder (ADHD) increased the risk by 8.7 times (p = 0.029, 95%CI 1.4-53.6). Older children were more predisposed to post-operative bleeding. For every increase in age by one year, the hemorrhage risk increased by 1.1 times (p = 0.0025, 95%CI 1.032-1.162). Children 11 years of age and older had double the risk of bleeding compared to younger children (odds ratio 1.98, p = 0.0381, 95%CI 1.04-3.79). None of the remaining 38 variables showed significant differences between cases and controls. Conclusions The risk of post-tonsillectomy hemorrhage is significantly increased in older children and those with recurrent tonsillitis and ADHD.
As threats from climate change increase across the world, climate-induced migration is receiving more attention, particularly as it affects people in the Global South. However, despite increasing ...extreme weather events in nations including the United States, limited research has examined public perceptions of the personal likelihood of migration among members of wealthy industrialized countries. We asked a national probability sample of 1,000 U.S. adults about the likelihood that they would have to relocate in the next ten years because of weather or climate-related issues. We found that a majority of respondents (57.0%) reported that these would have a “moderate” or greater influence on their decision to move in the coming decade. Logistic regression analysis with demographic (race, gender, socioeconomic status, and political party affiliation) and geographic indicators (regional division and coastal proximity) revealed that Democrats and people with higher education were more likely to indicate that weather or climate-related issues would factor into their decision to relocate. Implications for climate change migration and public opinion research are discussed.
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