College Meets Community with Rebecca Twitchell

https://digitalcommons.providence.edu/psp470_2023/1007/thumbnail.jp

The History of Farm Foxes Undermines the Animal Domestication Syndrome

The Russian Farm-Fox Experiment is the best known experimental study in animal domestication. By subjecting a population of foxes to selection for tameness alone, Dimitry Belyaev generated foxes that possessed a suite of characteristics that mimicked those found across domesticated species. This \u27domestication syndrome\u27 has been a central focus of research into the biological pathways modified during domestication. Here, we chart the origins of Belyaev\u27s foxes in eastern Canada and critically assess the appearance of domestication syndrome traits across animal domesticates. Our results suggest that both the conclusions of the Farm-Fox Experiment and the ubiquity of domestication syndrome have been overstated. To understand the process of domestication requires a more comprehensive approach focused on essential adaptations to human-modified environments

Resistivity due to a Domain Wall in Ferromagnetic Metal

The resistivity due to a domain wall in ferromagnetic metallic wire is calculated based on the linear response theory. The interaction between conduction electrons and the wall is expressed in terms of a classical gauge field which is introduced by the local gauge transformation in the electron spin space. It is shown that the wall contributes to the decoherence of electrons and that this quantum correction can dominate over the Boltzmann resisitivity, leading to a decrease of resisitivity by nucleation of a wall. The conductance fluctuation due to the motion of the wall is also investigated. The results are compared with recent experiments.Comment: 9 pages, 3 figure

Quantum Relaxation of Magnetisation in Magnetic Particles

At temperatures below the magnetic anisotropy energy, monodomain magnetic systems (small particles, nanomagnetic devices, etc.) must relax quantum mechanically. This quantum relaxation must be mediated by the coupling to both nuclear spins and phonons (and electrons if either particle or substrate is conducting. We analyze the effect of each of these couplings, and then combine them. Conducting systems can be modelled by a "giant Kondo" Hamiltonian, with nuclear spins added in as well. At low temperatures, even microscopic particles on a conducting substrate (containing only $10-50$ spins) will have their magnetisation frozen over millenia by a combination of electronic dissipation and the "degeneracy blocking" caused by nuclear spins. Raising the temperature leads to a sudden unblocking of the spin dynamics at a well defined temperature. Insulating systems are quite different. The relaxation is strongly enhanced by the coupling to nuclear spins. At short times the magnetisation of an ensemble of particles relaxes logarithmically in time, after an initial very fast decay; this relaxation proceeds entirely via the nuclear spins. At longer times phonons take over, but the decay rate is still governed by the temperature-dependent nuclear bias field acting on the particles - decay may be exponential or power-law depending on the temperature. The most surprising feature of the results is the pivotal role played by the nuclear spins. The results are relevant to any experiments on magnetic particles in which interparticle dipolar interactions are unimportant. They are also relevant to future magnetic device technology.Comment: 30 pages, RevTex, e:mail , Submitted to J.Low Temp.Phys. on 1 Nov. 199

Noise Probe of the Dynamic Phase Separation in La2/3Ca1/3MnO3

Giant Random Telegraph Noise (RTN) in the resistance fluctuation of a macroscopic film of perovskite-type manganese oxide La2/3Ca1/3MnO3 has been observed at various temperatures ranging from 4K to 170K, well below the Curie temperature (TC = 210K). The amplitudes of the two-level-fluctuations (TLF) vary from 0.01% to 0.2%. We use a statistical analysis of the life-times of the TLF to gain insight into the microscopic electronic and magnetic state of this manganite. At low temperature (below 30K) The TLF is well described by a thermally activated two-level model. An estimate of the energy difference between the two states is inferred. At higher temperature (between 60K and 170K) we observed critical effects of the temperature on the life-times of the TLF. We discuss this peculiar temperature dependence in terms of a sharp change in the free energy functional of the fluctuators. We attribute the origin of the RTN to be a dynamic mixed-phase percolative conduction process, where manganese clusters switch back and forth between two phases that differ in their conductivity and magnetization.Comment: 15 pages, PDF only, Phys. Rev. Lett. (in press

Results from Ireland north and south\u27s 2016 report card on physical activity for children and youth

Background: Physical activity (PA) is a key performance indicator for policy documents in both the Republic of Ireland and Northern Ireland. Building on baseline grades set in 2014, Ireland\u27s second Report Card on Physical Activity for Children and Youth allows for continued surveillance of indicators related to PA in children and youth. Methods: Data and information were extracted and collated for 10 indicators and graded using an international standardized grading system. Results: Overall, 7 grades stayed the same, 2 increased, and 1 decreased. Grades were assigned as follows: Overall PA, D (an increase); Sedentary Behavior (TV), C-; Physical Education, D-; Active Play, Incomplete/Inconclusive (INC); Active Transportation, D; School, D (a decrease); Home (Family), INC; Community and the Built Environment, B+ (an increase); and Government, INC. Unlike 2014\u27s report card, different grades for the Republic (C-) and Northern Ireland (C+) were assigned for Organized Sport Participation. Conclusions: Although the grade for Overall PA levels increased to a D, this may reflect the increased quality and quantity of data available. The double burden of low PA and high sedentary levels are concerning and underscore the need for advocacy toward, and surveillance of, progress in achieving targets set by the new National Physical Activity Plan in the Republic and obesity and sport plans in the North

Results from Ireland's 2014 Report Card on Physical Activity in Children and Youth

peer-reviewedBackground: Physical activity (PA) levels are a key performance indicator for policy documents in Ireland. The first Ireland Report Card on Physical Activity in Children and Youth aims to set a robust baseline for future surveillance of indicators related to PA in children and youth. Methods: Data collected between 2003-2010 on more than 35,000 7- to 18-year-old children and youth were used and graded using a standardized grading system for 10 indicators. Results: Grades assigned for the indicators were as follows: overall physical activity levels, D-; sedentary behavior (TV viewing), C-; organized sport participation, C-: physical education, D-; active play, inconclusive (INC); active transportation, D; school, C-, community and the built environment, B; family, INC; and government, INC. Conclusions: PA recommendations exist in Ireland but this Report Card has shown that participation is still low. A number of promising policies, programs and services are in place but these require thorough evaluation and adequate resourcing. Agreement and implementation of a common framework for the systematic surveillance of indictors related to PA of children and youth is necessary to monitor change over time and ensure the impact of promising work is captured.peer-reviewe

Human Platelet-Rich Plasma- and Extracellular Matrix-Derived Peptides Promote Impaired Cutaneous Wound Healing In Vivo

Previous work in our laboratory has described several pro-angiogenic short peptides derived from endothelial extracellular matrices degraded by bacterial collagenase. Here we tested whether these peptides could stimulate wound healing in vivo. Our experiments demonstrated that a peptide created as combination of fragments of tenascin X and fibrillin 1 (comb1) applied into cranial dermal wounds created in mice treated with cyclophosphamide to impair wound healing, can improve the rate of wound closure. Furthermore, we identify and characterize a novel peptide (UN3) created and modified from two naturally-occurring peptides, which are present in human platelet-rich plasma. In vitro testing of UN3 demonstrates that it causes a 50% increase in endothelial proliferation, 250% increase in angiogenic response and a tripling of epithelial cell migration in response to injury. Results of in vivo experiments where comb1 and UN3 peptides were added together to cranial wounds in cyclophosphamide-treated mice leads to improvement of wound vascularization as shown by an increase of the number of blood vessels present in the wound beds. Application of the peptides markedly promotes cellular responses to injury and essentially restores wound healing dynamics to those of normal, acute wounds in the absence of cyclophosphamide impairment. Our current work is aimed at understanding the mechanisms underlying the stimulatory effects of these peptides as well as identification of the cellular receptors mediating these effects.National Institutes of Health (U.S.) (Grant EY15125)National Institutes of Health (U.S.) (Grant EY19533)Wound Care Partners, LL

Proteome changes in platelets activated by arachidonic acid, collagen, and thrombin

<p>Abstract</p> <p>Background</p> <p>Platelets are small anucleated blood particles that play a key role in the control of bleeding. Platelets need to be activated to perform their functions and participate in hemostasis. The process of activation is accompanied by vast protein reorganization and posttranslational modifications. The goal of this study was to identify changes in proteins in platelets activated by different agonists. Platelets were activated by three different agonists - arachidonic acid, collagen, and thrombin. 2D SDS-PAGE (pI 4-7) was used to separate platelet proteins. Proteomes of activated and resting platelets were compared with each other by Progenesis SameSpots statistical software; and proteins were identified by nanoLC-MS/MS.</p> <p>Results</p> <p>190 spots were found to be significantly different. Of these, 180 spots were successfully identified and correspond to 144 different proteins. Five proteins were found that had not previously been identified in platelets: protein CDV3 homolog, protein ETHE1, protein LZIC, FGFR1 oncogene partner 2, and guanine nucleotide-binding protein subunit beta-5. Using spot expression profile analysis, we found two proteins (WD repeat-containing protein 1 and mitochondrial glycerol-3-phosphate dehydrogenase) that may be part of thrombin specific activation or signal transduction pathway(s).</p> <p>Conclusions</p> <p>Our results, characterizing the differences within proteins in both activated (by various agonists) and resting platelets, can thus contribute to the basic knowledge of platelets and to the understanding of the function and development of new antiplatelet drugs.</p

Speech delays and behavioral problems are the predominant features in individuals with developmental delays and 16p11.2 microdeletions and microduplications

Microdeletions and microduplications encompassing a ~593-kb region of 16p11.2 have been implicated as one of the most common genetic causes of susceptibility to autism/autism spectrum disorder (ASD). We report 45 microdeletions and 32 microduplications of 16p11.2, representing 0.78% of 9,773 individuals referred to our laboratory for microarray-based comparative genomic hybridization (aCGH) testing for neurodevelopmental and congenital anomalies. The microdeletion was de novo in 17 individuals and maternally inherited in five individuals for whom parental testing was available. Detailed histories of 18 individuals with 16p11.2 microdeletions were reviewed; all had developmental delays with below-average intelligence, and a majority had speech or language problems or delays and various behavioral problems. Of the 16 individuals old enough to be evaluated for autism, the speech/behavior profiles of seven did not suggest the need for ASD evaluation. Of the remaining nine individuals who had speech/behavior profiles that aroused clinical suspicion of ASD, five had formal evaluations, and three had PDD-NOS. Of the 19 microduplications with parental testing, five were de novo, nine were maternally inherited, and five were paternally inherited. A majority with the microduplication had delayed development and/or specific deficits in speech or language, though these features were not as consistent as seen with the microdeletions. This study, which is the largest cohort of individuals with 16p11.2 alterations reported to date, suggests that 16p11.2 microdeletions and microduplications are associated with a high frequency of cognitive, developmental, and speech delay and behavior abnormalities. Furthermore, although features associated with these alterations can be found in individuals with ASD, additional factors are likely required to lead to the development of ASD