Phenomenological model of diffuse global and regional atrophy using finite-element methods

The main goal of this work is the generation of ground-truth data for the validation of atrophy measurement techniques, commonly used in the study of neurodegenerative diseases such as dementia. Several techniques have been used to measure atrophy in cross-sectional and longitudinal studies, but it is extremely difficult to compare their performance since they have been applied to different patient populations. Furthermore, assessment of performance based on phantom measurements or simple scaled images overestimates these techniques' ability to capture the complexity of neurodegeneration of the human brain. We propose a method for atrophy simulation in structural magnetic resonance (MR) images based on finite-element methods. The method produces cohorts of brain images with known change that is physically and clinically plausible, providing data for objective evaluation of atrophy measurement techniques. Atrophy is simulated in different tissue compartments or in different neuroanatomical structures with a phenomenological model. This model of diffuse global and regional atrophy is based on volumetric measurements such as the brain or the hippocampus, from patients with known disease and guided by clinical knowledge of the relative pathological involvement of regions and tissues. The consequent biomechanical readjustment of structures is modelled using conventional physics-based techniques based on biomechanical tissue properties and simulating plausible tissue deformations with finite-element methods. A thermoelastic model of tissue deformation is employed, controlling the rate of progression of atrophy by means of a set of thermal coefficients, each one corresponding to a different type of tissue. Tissue characterization is performed by means of the meshing of a labelled brain atlas, creating a reference volumetric mesh that will be introduced to a finite-element solver to create the simulated deformations. Preliminary work on the simulation of acquisition artefa- - cts is also presented. Cross-sectional and

Primjena bioraspoloživosti u postavljanju standarda za procjenu rizika: sugestije temeljene na seminaru s naglaskom na metale

Bioavailability is increasingly recognised as the key issue linking increased levels of toxicants with actually occurring adverse effects in ecosystems, whilst taking the modifying effects of the abiotic components of the environment into account. Various factors may affect bioavailability in the field, and often these factors are time- and space-dependent. This is one of the main reasons why legislators have been reluctant in implementing bioavailability in risk assessment procedures. Over the last few years, however, considerable scientific progress has been made with regard to better understanding of chemical and ecological mechanisms responsible for rendering chemicals available for uptake and toxicity. As a consequence, legislators face the challenge to anticipate the scientific progress and to implement bioavailability in legislation. This paper discusses the possibilities of implementing various methodologies within a maximum period of time of three years.Biološka dostupnost sve se više smatra ključnim problemom vezanim s povećanom razinom toksičnih tvari što izazivaju neželjene učinke u ekosustavima pri čemu se uzimaju u obzir promjenljivi učinci abiotičkih sustava okoliša. Mnogi čimbenici mogu utjecati na biološku dostupnost u prirodi. Ovi su čimbenici i vremenski i prostorno ovisni. To je i glavni razlog zašto su zakonodavci oklijevali primijeniti biološku dostupnost u procese procjene rizika. Proteklih je godina, međutim, napravljen značajan napredak s obzirom na bolje razumijevanje kemijskih i ekoloških mehanizama odgovornih za dostupnost kemikalija apsorpciji i za njihovu toksičnost. Kao posljedica toga zakonodavci se suočavaju s izazovom da prihvate znanstveni napredak i primijene biološku dostupnost u zakonima. Ovaj članak raspravlja mogućnosti raznih metodologija u razdoblju od tri godine

Antagonistic Contact and Inverse Affiliation: Appropriation of /TH/-fronting by White Speakers in South Philadelphia

This paper examines a group of white speakers in South Philadelphia who exhibit appropriation of African American Vernacular English /TH/-fronting. Speakers with the most antagonistic contact and most aggressive attitudes toward their African American neighbors show the highest rates of /TH/-fronting. This paper argues that appropriation of the African American Vernacular English (AAVE) ethnolect feature of /TH/-fronting has been reanalyzed as a marker of street smarts rather than as a marker of speakers’ affiliations with AAVE speakers

Where our Fathers are from: Place and Conflict in Sociolinguistic Borrowing

In this paper, I set sociolinguistic meaning and phonological borrowing within the specific local geography of speakers in a community. The social practices of these speakers collide with ideology in a particular physical space: a single neighborhood park that serves as a neighborhood boundary between Black and white residents in a Philadelphia neighborhood, which in turn emerges in the white speakers’ ideologies as a place that is both maximally local and is the site of contact with the maximally extralocal. I argue that the interleaving of social meanings within the park and the regular interracial conflict within it result in the indexical de-linking of (TH)-fronting from African American English (AAE) and the indexical strengthening of this feature with toughness, enabling white Philadelphia English speakers to adopt this (TH)-fronting as an index of tough via conflict with their AAE speaking neighbors

Mechanisms Of Phonological Change

The traditional Philadelphia allophonic /æ/ system (henceforth: PHL shown in (1) below) is characterized by a set of complicated conditioning factors and a dramatic acoustic distinction between the two allophones. In recent years, some Philadelphians have begun to exhibit a new allophonic system (NAS, shown in (2) below). Like PHL, NAS is characterized by a dramatic acoustic distinction between tense and lax allophones. NAS is quickly overtaking PHL in the Philadelphia community, as demonstrated by Labov et al. (2016). (1) PHL: æ→æh/ _ [+anterior] ∩( [+nasal] ∪ [-voice + fricative) ]σ (2) NAS: æ→æh/ +nasal This situation offers an exciting opportunity to observe phonological change in individual speakers. Most phonological changes involve the collapse or creation of a new phonological category; because of the large degree of acoustic overlap in these situations, it is difficult or impossible to identity individual tokens as having been produced by the old or the new phonology. In the current change in Philadelphia /æ/, however, both the old and the new system involve distinct acoustic targets, making it possible to identify which underlying system was used to produce a given word. It is therefore possible to test several distinct theories about phonological change: Whether change occurs through gradual phonetic incrementation (e.g. Ohala 1981), through individual speakers producing only the old or the new system (e.g., Janda and Joseph 2003), or whether change occurs via individual speakers probabilistically producing both the old and the new system in a process of individual grammar competition (e.g., Fruehwald et al. 2013). In my dissertation, I examine natural speech production from 46 speakers who acquired language during the period of allophonic change, with a combination of topic-directed conversations and targeted natural language experiments. Using a glm classifier, I identify tokens of /æ/ as having been produced by either PHL or NAS. In concert with an analysis of speakers’ social histories, I use these results to argue that the change from PHL to NAS in Philadelphia is driven by the mechanism of competing grammars, suggesting that both syntactic change and phonological change proceed in the same manner. My research provides one of the first pieces of direct empirical support for a unified theory of language change in which structural changes in syntax and phonology are implemented through the same mechanism of grammar competition (Kroch, 1989; Fruehwald et al., 2013). In addition to the theoretical contribution to phonological change, my dissertation also traces the social patterns of the allophonic change, highlighting the effect of network structure and access to elite education on the adoption of the incoming allophonic system. I also employ experimental methods to demonstrate that the abstract allophonic rules of /æ/ are the target of social evaluation and contribute to social meaning. I find speakers producing surprisingly systematic evaluations of PHL and NAS, a result which only emerges when analyzing the evaluation of changing abstract parameters. Finally, to test whether the change from PHL to NAS was the inevitable result of phono- logical simplification, I developed a computational simulation built using a principle of language acquisition (Yang, 2016) to demonstrate that the allophonic restructuring in /æ/ was not the result of children simplifying their input data, but rather must have been the result of dialect contact with in-moving speakers of the new system

The Radical Imagination: Exploring the Intersection of the Youth-led Climate Justice Movement and Education

This paper explores the crossover of the youth-led climate justice movement and education, utilizing The Experiment Digital Climate Change & the Environment as a case study to investigate this crossover globally and locally. A 6-week virtual exchange program designed to connect 100 high school students from 23 countries, The Experiment Digital Climate Change & the Environment aimed to equip youth with radical tools to address the scale of the climate crisis. The study drew on the neo-institutionalism and systems thinking approaches to globalization. Employing qualitative research methods, including a questionnaire and individual interviews, the findings revealed that international relationships improved critical thinking and collaboration. In combination with systems change curriculum, the program spurred increased action in the youth-led movement. Findings confirmed that there is no one solution for educating on climate justice. Communities need to tailor their systems and pedagogy to their geographic locations, demographics and cultures. The study’s key contributions to scholarship include comprehensive systems change curriculum, the solidified connection between education and increased activism, and documenting perspectives on climate justice from exceedingly diverse participants

Where our Fathers are from: Place and Conflict in Sociolinguistic Borrowing

In this paper, I set sociolinguistic meaning and phonological borrowing within the specific local geography of speakers in a community. The social practices of these speakers collide with ideology in a particular physical space: a single neighborhood park that serves as a neighborhood boundary between Black and white residents in a Philadelphia neighborhood, which in turn emerges in the white speakers’ ideologies as a place that is both maximally local and is the site of contact with the maximally extralocal. I argue that the interleaving of social meanings within the park and the regular interracial conflict within it result in the indexical de-linking of (TH)-fronting from African American English (AAE) and the indexical strengthening of this feature with toughness, enabling white Philadelphia English speakers to adopt this (TH)-fronting as an index of tough via conflict with their AAE speaking neighbors

Training for understanding: a model for mediating abstract statistical concepts

The use of training models is suggested as an instructional tool facilitating understanding of abstract concepts as measured by transfer to problem solving settings. A three stage model was developed to mediate the transfer of attributes and structures from known concrete concepts to unknown abstract concepts. Student groups received computer based training followed by post-tests for factual retention, near transfer of model procedures (non-novel problems), and far transfer of model procedures (novel problems). Two test groups of university students received training using the developed training model and instruction using abstract statistical concepts. Two control groups received either model or statistical concept training but not both. Results indicate that the model training used did improve factual retention but not increase related near and far transfer in the statistical problem solving situation