408 research outputs found
Mechanisms responsible for the development of causal perception in infancy.
The aim of the current dissertation was to investigate the mechanisms that contribute to the emergence of causal perception in infancy. Previous research suggests that the experience of self-produced causal action may be necessary to promote the development of causal perception (Rakison & Krogh, 2012). The goal of the current study was two-fold: (1) to further explore the roles of self-produced action, haptic, proprioceptive and visual information, and parental interaction on young infantsâ understanding of causality. To assess the impact of these factors on infantsâ causal learning, 4½-month-olds were randomly assigned to one four conditions. Three of the conditions (Active with Parent Interaction, Active Without Parent Interaction, and Passive with Parent Interaction) provided infants with object-manipulation training in which infants wore âsticky mittensâ that allowed them to manipulate Velcro-covered toys. The fourth condition was a no-training control condition. Following training, infantsâ ability to perceive the difference between causal and non-causal versions of simple collision events (one ball colliding with another) was tested. It was hypothesized that both of the active training conditions would facilitate infantsâ causal perception, while passive training would produce no effects relative to the control condition. Results demonstrated that 4½-month-old infants who received no training, and same-aged infants who received passive training that controlled for perceptual aspects of self-produced causal action experience (haptic, proprioceptive, and visual information), did not show evidence of causal perception. As hypothesized, active training experience facilitated causal perception in 4½-month-olds. However, surprisingly, active training only facilitated learning in the condition in which parents were instructed not to interact with their infants. Comparisons of the two active training groups (with and without parent interaction) revealed that the groups did not differ on a number of infant characteristics and behaviors. The results of this study suggest: (1) self-produced causal actions constitute a mechanism by which causal perception arises in infancy, and (2) parental interactions during infantsâ object explorations may interfere with learning
Effekter av gjødsling med nitrogen og aske i et rikt granbestand pĂĽ Ăstlandet
I norsk skog pĂĽ mineraljord er det stort sett nitrogen (N) som gir positivt utslag pĂĽ trĂŚrnes vekst. Men ogsĂĽ andre nĂŚringsstoffer kan i visse tilfeller øke veksten, blant annet i bestand pĂĽ høy bonitet. Treaske inneholder bĂĽde fosfor og kalium i tillegg til andre nĂŚringsstoffer, og har en kalkvirkning. Asken kan derfor vĂŚre en bĂŚrekraftig gjødselressurs. I 2012 ble det anlagt et forsøk i Hobøl, Viken, hvor en rik granskog ble gjødslet med N (15 kg per daa), treaske (300 kg per daa) og en kombinasjon. Vi studerte effektene pĂĽ trĂŚr, vegetasjon og jordsmonn. Humuskjemien ble undersøkt før behandling og to ĂĽr etter, og jordvannkjemien under vekstsesongen i samme periode. TrĂŚrnes tilvekst ble undersøkt etter fem og ti ĂĽr, og effekter pĂĽ vegetasjonen etter to og ni. Ren N-gjødsling ga en viss effekt pĂĽ trĂŚrnes tilvekst. Etter ti ĂĽr var det ikke lenger økt ĂĽrringvekst etter N-gjødsling. Derimot var effekten av ĂĽ tilføre aske sammen med N god. Effekten av ren aske var liten i starten, men stigende gjennom perioden. Resultatene bekrefter at asketilførsel pĂĽ fastmark kan gi positive tilveksteffekter pĂĽ felt med god bonitet, men sĂŚrlig i kombinasjon med N. To ĂĽr etter gjødsling fant vi smĂĽ effekter pĂĽ mangfold av karplanter, men redusert mangfold av moser og lav. Antall og dekning av urter hadde økt i alle gjødslingsbehandlingene etter ni ĂĽr, mens artsmangfold av bladmoser og levermoser var ytterligere redusert. Dekningen av blĂĽbĂŚr og store moser som etasjemose og furumose økte i alle behandlinger, og antyder at andre faktorer enn gjødslingen ogsĂĽ bidro. Det ble ikke funnet signifikante effekter av ĂĽ tilføre aske eller aske + N pĂĽ karbon- eller N-innholdet i humusen. Plantetilgjengelig konsentrasjon av flere andre stoffer som aluminium, kobolt, jern, nikkel, bly og sink gikk ned etter asketilførsel. Jordvannet viste kortvarige økninger av nitrat, ammonium og ulike grunnstoffer, samt lavere pH, etter tilførsel av N. Askegjødsling ga ikke effekter pĂĽ jordvannkjemien.Effekter av gjødsling med nitrogen og aske i et rikt granbestand pĂĽ ĂstlandetpublishedVersio
Physical Structure and Nature of Supernova Remnants in M101
Supernova remnant (SNR) candidates in the giant spiral galaxy M101 have been
previously identified from ground-based H-alpha and [SII] images. We have used
archival Hubble Space Telescope (HST) H-alpha and broad-band images as well as
stellar photometry of 55 SNR candidates to examine their physical structure,
interstellar environment, and underlying stellar population. We have also
obtained high-dispersion echelle spectra to search for shocked high-velocity
gas in 18 SNR candidates, and identified X-ray counterparts to SNR candidates
using data from archival observations made by the Chandra X-ray Observatory.
Twenty-one of these 55 SNR candidates studied have X-ray counterparts, although
one of them is a known ultra-luminous X-ray source. The multi-wavelength
information has been used to assess the nature of each SNR candidate. We find
that within this limited sample, ~16% are likely remnants of Type Ia SNe and
~45% are remnants of core-collapse SNe. In addition, about ~36% are large
candidates which we suggest are either superbubbles or OB/HII complexes.
Existing radio observations are not sensitive enough to detect the non-thermal
emission from these SNR candidates. Several radio sources are coincident with
X-ray sources, but they are associated with either giant HII regions in M101 or
background galaxies. The archival HST H-alpha images do not cover the entire
galaxy and thus prevents a complete study of M101. Furthermore, the lack of HST
[SII] images precludes searches for small SNR candidates which could not be
identified by ground-based observations. Such high-resolution images are needed
in order to obtain a complete census of SNRs in M101 for a comprehensive
investigation of the distribution, population, and rates of SNe in this galaxy.Comment: 37 pages, 4 Tables, 7 Figures, accepted for publication in the
Astronomical Journa
Familiesâ perceptions of and experiences related to a pediatric weight management program.
Objective: To examine parents' and children's perceptions of and experiences related to a Parents as Agents of Change (PAC) intervention for managing pediatric obesity. Methods: Ten families were recruited from a PAC intervention. Participants were interviewed before (10 adults and 9 children), during (9 adults and 8 children), and after (8 adults) the intervention. Results: Before the intervention, families reported goals to increase physical activity, plan and eat healthier meals, reduce screen time, and lose weight. During the intervention, families described different approaches to making behavior changes depending on who assumed responsibility (parent, child, or shared responsibility). After the intervention, group setting, goal setting, and portion size activities were viewed positively. Suggestions for improvement included engaging children and reducing intervention length. Conclusions and Implications: Practitioners delivering PAC interventions should discuss families' goals and concerns, and who is responsible for making lifestyle changes. Practical activities are valuable. The length of interventions and engagement of children should be considere
Gravity waves in the winter stratosphere over the Southern Ocean: high-resolution satellite observations and 3-D spectral analysis.
Atmospheric gravity waves play a key role in the transfer of energy and momentum between layers of the Earth's atmosphere. However, nearly all Global Circulation Models (GCMs) seriously under-represent the momentum fluxes of gravity waves at latitudes near 60°âS. This can result in modelled winter stratospheres that are unrealistically cold â a significant bias known as the "cold-pole problem". There is thus a need for measurements of gravity-wave fluxes near 60S to test and constrain GCMs. Such measurements are notoriously difficult, because they require 3-D observations of wave properties if the fluxes are to be estimated without using significant limiting assumptions. Here we use 3-D satellite measurements of stratospheric gravity waves from NASA's AIRS/Aqua instrument. We present the first extended application of a 3-D Stockwell transform (3DST) method to determine localised gravity-wave amplitudes, wavelengths and directions of propagation around the entire region of the Southern Ocean near 60°âS during austral winter 2010. We first validate our method using a synthetic wave field and two case studies of real gravity waves over the Southern Andes and the island of South Georgia. A new technique to overcome wave amplitude attenuation problems in previous methods is also presented. We then characterise large-scale gravity-wave occurrence frequencies, directional momentum fluxes and short-timescale intermittency over the entire Southern Ocean. Our results show that highest wave-occurrence frequencies, amplitudes and momentum fluxes are observed in the stratosphere over the mountains of the Southern Andes and Antarctic Peninsula. However, we find that around 60â80â% of total zonal-mean momentum flux is located over the open Southern Ocean during JuneâAugust, where a large "belt" of increased wave-occurrence frequencies, amplitudes and fluxes is observed. Our results also suggest significant short-timescale variability of fluxes from both orographic and non-orographic sources in the region. A particularly striking result is a widespread convergence of gravity-wave momentum fluxes towards latitudes around 60°âS from the north and south. We propose that this convergence, which is observed at nearly all longitudes during winter, accounts for a significant part of the under-represented flux in GCMs at these latitudes
A grounded theory of positive youth development through sport based on results from a qualitative meta-study
The overall purpose of this study was to create a model of positive youth development (PYD) through sport grounded in the extant qualitative literature. More specifically, the first objective was to review and evaluate qualitative studies of PYD in sport. The second objective was to analyze and synthesize findings from these studies. Following record identification and screening, 63 articles were retained for analysis. Meta-method analysis revealed strengths of studies were the use of multiple data collection and validity techniques, which produced high-quality data. Weaknesses were limited use of ânamedâ methodologies and inadequate reporting of sampling procedures. Philosophical perspectives were rarely reported, and theory was used sparingly. Results of an inductive meta-data analysis produced three categories: PYD climate (adult relationships, peer relationships, and parental involvement), life skills program focus (life skill building activities and transfer activities), and PYD outcomes (in personal, social, and physical domains). A model that distinguishes between implicit and explicit processes to PYD is presented
The Douglas-Fir Genome Sequence Reveals Specialization of the Photosynthetic Apparatus in Pinaceae.
A reference genome sequence for Pseudotsuga menziesii var. menziesii (Mirb.) Franco (Coastal Douglas-fir) is reported, thus providing a reference sequence for a third genus of the family Pinaceae. The contiguity and quality of the genome assembly far exceeds that of other conifer reference genome sequences (contig N50 = 44,136 bp and scaffold N50 = 340,704 bp). Incremental improvements in sequencing and assembly technologies are in part responsible for the higher quality reference genome, but it may also be due to a slightly lower exact repeat content in Douglas-fir vs. pine and spruce. Comparative genome annotation with angiosperm species reveals gene-family expansion and contraction in Douglas-fir and other conifers which may account for some of the major morphological and physiological differences between the two major plant groups. Notable differences in the size of the NDH-complex gene family and genes underlying the functional basis of shade tolerance/intolerance were observed. This reference genome sequence not only provides an important resource for Douglas-fir breeders and geneticists but also sheds additional light on the evolutionary processes that have led to the divergence of modern angiosperms from the more ancient gymnosperms
Pseudogene accumulation in the evolutionary histories of Salmonella enterica serovars Paratyphi A and Typhi
<p>Abstract</p> <p>Background</p> <p>Of the > 2000 serovars of <it>Salmonella enterica </it>subspecies I, most cause self-limiting gastrointestinal disease in a wide range of mammalian hosts. However, <it>S. enterica </it>serovars Typhi and Paratyphi A are restricted to the human host and cause the similar systemic diseases typhoid and paratyphoid fever. Genome sequence similarity between Paratyphi A and Typhi has been attributed to convergent evolution via relatively recent recombination of a quarter of their genomes. The accumulation of pseudogenes is a key feature of these and other host-adapted pathogens, and overlapping pseudogene complements are evident in Paratyphi A and Typhi.</p> <p>Results</p> <p>We report the 4.5 Mbp genome of a clinical isolate of Paratyphi A, strain AKU_12601, completely sequenced using capillary techniques and subsequently checked using Illumina/Solexa resequencing. Comparison with the published genome of Paratyphi A ATCC9150 revealed the two are collinear and highly similar, with 188 single nucleotide polymorphisms and 39 insertions/deletions. A comparative analysis of pseudogene complements of these and two finished Typhi genomes (CT18, Ty2) identified several pseudogenes that had been overlooked in prior genome annotations of one or both serovars, and identified 66 pseudogenes shared between serovars. By determining whether each shared and serovar-specific pseudogene had been recombined between Paratyphi A and Typhi, we found evidence that most pseudogenes have accumulated after the recombination between serovars. We also divided pseudogenes into relative-time groups: ancestral pseudogenes inherited from a common ancestor, pseudogenes recombined between serovars which likely arose between initial divergence and later recombination, serovar-specific pseudogenes arising after recombination but prior to the last evolutionary bottlenecks in each population, and more recent strain-specific pseudogenes.</p> <p>Conclusion</p> <p>Recombination and pseudogene-formation have been important mechanisms of genetic convergence between Paratyphi A and Typhi, with most pseudogenes arising independently after extensive recombination between the serovars. The recombination events, along with divergence of and within each serovar, provide a relative time scale for pseudogene-forming mutations, affording rare insights into the progression of functional gene loss associated with host adaptation in <it>Salmonella</it>.</p
Shigella sonnei genome sequencing and phylogenetic analysis indicate recent global dissemination from Europe
Shigella are human-adapted Escherichia coli that have gained the ability to invade the human gut mucosa and cause dysentery1,2, spreading efficiently via low-dose fecal-oral transmission3,4. Historically, S. sonnei has been predominantly responsible for dysentery in developed countries, but is now emerging as a problem in the developing world, apparently replacing the more diverse S. flexneri in areas undergoing economic development and improvements in water quality4-6. Classical approaches have shown S. sonnei is genetically conserved and clonal7. We report here whole-genome sequencing of 132 globally-distributed isolates. Our phylogenetic analysis shows that the current S. sonnei population descends from a common ancestor that existed less than 500 years ago and has diversified into several distinct lineages with unique characteristics. Our analysis suggests the majority of this diversification occurred in Europe, followed by more recent establishment of local pathogen populations in other continents predominantly due to the pandemic spread of a single, rapidly-evolving, multidrug resistant lineage
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