988 research outputs found
Toward a Quantitative Analysis of Online Communities
In flexible learning environments there has been an increased focus on developing resources that promote and facilitate the emergence of online communities. The formation of, and active participation in, a learning community has been suggested to facilitate the learning process (Rovai, 2002; Palloff & Pratt, 1999). Current literature examining the formation and development of online communities has predominantly centred on the qualitative analysis of posted messages (within an asynchronous discussion forum) as evidence for community attainment and sustainment (Brook & Oliver, 2003; Hew & Cheung, 2003). The search for key words and phrases is conducted regardless of timing and position within the threaded discussion. Hence, analysis of the postings often occurs in a manner that de-contextualises the discourse throughout the delivery of a subject (Misanchuk & Dueber, 2001). Furthermore, as analysis is limited to a few disparate units of study, an overall picture of the extent to which the online communities formed in individual units are supporting the strategic goals of the university is not formed. Investment in online technologies and development of learning and teaching strategies is conducted at an enterprise level. However, current methodologies evaluating the development and sustainment of online communities have been focussed at a localised level. This paper proposes a scaleable quantitative approach to identify the degree of learner interactions occurring in specific subject-based forums for further qualitative analysis. It is proposed that the examination of data derived from the wider University context better positions and informs staff undertaking subject-based forums in order to align with University strategic goals
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New machine-marked tests for selection into core medical training: evidence from two validation studies
The objective of this study was to examine whether two machine-marked tests (MMTs), a clinical problem-solving test (CPS) and a situational judgement test (SJT, focusing on professional dilemmas), previously validated for selection into general practice (GP) training in the UK, could provide a valid selection methodology for shortlisting into core medical training (CMT). An exploratory longitudinal design was used to examine the psychometric properties of the MMTs for CMT applicants, and the correlation between MMT scores (time 1) and subsequent CMT interview outcomes (time 2). Independent samples from two consecutive years were used: in 2008 a retrospective analysis of data was used, while in 2009, doctors applying for CMT were asked to complete the MMTs for evaluation purposes. In 2008, a total of 1,711 doctors applied to both CMT and GP training and completed the MMTs. In 2009, a total of 2,265 doctors who applied for CMT completed the MMTs for evaluation purposes. The main outcome measure was the CMT applicants’ interview score. Both the CPS and SJT had good reliability and score distributions for 2008 and 2009 CMT samples, similar to the GP comparison samples. The MMTs were good predictors of performance in the CMT interviews (r0.56, p0.001 in 2008, and r0.61, p0.001 in 2009 for both MMTs combined) and offered incremental validity over the current shortlisting process. The GP MMTs offer an appropriate measurement methodology for selection into CMT, representing a significant innovation for developing selection methodology for CMT. Longer-term studies should be undertaken to assess the validity of all selection techniques used, in terms of CMT training outcome
Structural Features Underlying Raloxifene’s Biophysical Interaction with Bone Matrix
Raloxifene, a selective estrogen receptor modulator (SERM), reduces fracture risk at least in part by improving the mechanical properties of bone in a cell- and estrogen receptor-independent manner. In this study, we determined that raloxifene directly interacts with the bone tissue. Through the use of multiple and complementary biophysical techniques including nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR), we show that raloxifene interacts specifically with the organic component or the organic/mineral composite, and not with hydroxyapatite. Structure–activity studies reveal that the basic side chain of raloxifene is an instrumental determinant in the interaction with bone. Thus, truncation of portions of the side chain reduces bone binding and also diminishes the increase in mechanical properties. Our results support a model wherein the piperidine interacts with bone matrix through electrostatic interactions with the piperidine nitrogen and through hydrophobic interactions (van der Waals) with the aliphatic groups in the side chain and the benzothiophene core. Furthermore, in silico prediction of the potential binding sites on the surface of collagen revealed the presence of a groove with sufficient space to accommodate raloxifene analogs. The hydroxyl groups on the benzothiophene nucleus, which are necessary for binding of SERMs to the estrogen receptor, are not required for binding to the bone surface, but mediate a more robust binding of the compound to the bone powder. In conclusion, we report herein a novel property of raloxifene analogs that allows them to interact with the bone tissue through potential contacts with the organic matrix and in particular collagen
Dysregulation in Subcellular Localization of Myelin Basic Protein mRNA Does Not Result in Altered Myelination in Amyotrophic Lateral Sclerosis
Pathological hallmarks of amyotrophic lateral sclerosis (ALS), including protein misfolding, are well established in oligodendrocytes. More recently, an RNA trafficking deficit of key myelin proteins has been suggested in oligodendrocytes in ALS but the extent to which this affects myelination and the relative contribution of this to disease pathogenesis is unclear. ALS autopsy research findings showing demyelination contrasts with the routine clinical-pathological workup of ALS cases where it is rare to see white matter abnormalities other than simple Wallerian degeneration secondary to widespread neuronal loss. To begin to address this apparent variance, we undertook a comprehensive evaluation of myelination at an RNA, protein and structural level using human pathological material from sporadic ALS patients, genetic ALS patients (harboring C9orf72 mutation) and age- and sex-matched non-neurological controls. We performed (i) quantitative spatial profiling of the mRNA transcript encoding myelin basic protein (MBP), (ii) quantification of MBP protein and (iii) the first quantitative structural assessment of myelination in ALS post-mortem specimens by electron microscopy. We show no differences in MBP protein levels or ultrastructural myelination, despite a significant dysregulation in the subcellular trafficking of MBP mRNA in ALS patients compared to controls. We therefore confirm that whilst there are cell autonomous mRNA trafficking deficits affecting oligodendrocytes in ALS, this has no effect on myelin structure
Mitochondrial bioenergetic deficits in C9orf72 amyotrophic lateral sclerosis motor neurons cause dysfunctional axonal homeostasis
ARM is a Lady Edith Wolfson Clinical Fellow and is jointly funded by the Medical Research Council (MRC) and the Motor Neurone Disease Association (MR/R001162/1). He also acknowledges support from the Rowling Scholars scheme, administered by the Anne Rowling Regenerative Neurology Clinic (ARRNC), University of Edinburgh, and a seedcorn grant from The Chief Scientist Office and the RS Macdonald Charitable Trust via the Scottish Neurological Research Fund, administered by the University of St Andrews. JMG is funded by a starter grant for clinical lecturers from the Academy of Medical Sciences. CS is supported by a Medical Research Council grant (MR/L016400/1). NMM was funded by a Wellcome Trust New Investigator Award (100981/Z/13/Z). RNC and NMM are funded by a Diabetes UK grant (17/0005697). The Hardingham and Chandran laboratories are supported by the Euan MacDonald Centre for Motor Neurone Disease Research, and the UK Dementia Research Institute (DRI), which receives its funding from UK DRI Ltd, funded by the MRC, Alzheimer's Society and Alzheimer's Research UK. SC also acknowledges funding from the ARRNC, My Name’5 Doddie Foundation, and an MRC Dementias Platform UK Stem Cell Partnership grant (MR/N013255/1). BTS is a Rowling-DRI Fellow.Peer reviewedPublisher PD
Dysregulation in Subcellular Localization of Myelin Basic Protein mRNA Does Not Result in Altered Myelination in Amyotrophic Lateral Sclerosis
Pathological hallmarks of amyotrophic lateral sclerosis (ALS), including protein misfolding, are well established in oligodendrocytes. More recently, an RNA trafficking deficit of key myelin proteins has been suggested in oligodendrocytes in ALS but the extent to which this affects myelination and the relative contribution of this to disease pathogenesis is unclear. ALS autopsy research findings showing demyelination contrasts with the routine clinical-pathological workup of ALS cases where it is rare to see white matter abnormalities other than simple Wallerian degeneration secondary to widespread neuronal loss. To begin to address this apparent variance, we undertook a comprehensive evaluation of myelination at an RNA, protein and structural level using human pathological material from sporadic ALS patients, genetic ALS patients (harboring C9orf72 mutation) and age- and sex-matched non-neurological controls. We performed (i) quantitative spatial profiling of the mRNA transcript encoding myelin basic protein (MBP), (ii) quantification of MBP protein and (iii) the first quantitative structural assessment of myelination in ALS post-mortem specimens by electron microscopy. We show no differences in MBP protein levels or ultrastructural myelination, despite a significant dysregulation in the subcellular trafficking of MBP mRNA in ALS patients compared to controls. We therefore confirm that whilst there are cell autonomous mRNA trafficking deficits affecting oligodendrocytes in ALS, this has no effect on myelin structure.</p
Diverging phenological responses of Arctic seabirds to an earlier spring
The timing of annual events such as reproduction is a critical component of how free‐living organisms respond to ongoing climate change. This may be especially true in the Arctic, which is disproportionally impacted by climate warming. Here, we show that Arctic seabirds responded to climate change by moving the start of their reproduction earlier, coincident with an advancing onset of spring and that their response is phylogenetically and spatially structured. The phylogenetic signal is likely driven by seabird foraging behavior. Surface‐feeding species advanced their reproduction in the last 35 years while diving species showed remarkably stable breeding timing. The earlier reproduction for Arctic surface‐feeding birds was significant in the Pacific only, where spring advancement was most pronounced. In both the Atlantic and Pacific, seabirds with a long breeding season showed a greater response to the advancement of spring than seabirds with a short breeding season. Our results emphasize that spatial variation, phylogeny, and life history are important considerations in seabird phenological response to climate change and highlight the key role played by the species' foraging behavior
MSH3 polymorphisms and protein levels affect CAG repeat instability in huntington's disease mice
Expansions of trinucleotide CAG/CTG repeats in somatic tissues are thought to contribute to ongoing disease progression through an affected individual's life with Huntington's disease or myotonic dystrophy. Broad ranges of repeat instability arise between individuals with expanded repeats, suggesting the existence of modifiers of repeat instability. Mice with expanded CAG/CTG repeats show variable levels of instability depending upon mouse strain. However, to date the genetic modifiers underlying these differences have not been identified. We show that in liver and striatum the R6/1 Huntington's disease (HD) (CAG)~100 transgene, when present in a congenic C57BL/6J (B6) background, incurred expansion-biased repeat mutations, whereas the repeat was stable in a congenic BALB/cByJ (CBy) background. Reciprocal congenic mice revealed the Msh3 gene as the determinant for the differences in repeat instability. Expansion bias was observed in congenic mice homozygous for the B6 Msh3 gene on a CBy background, while the CAG tract was stabilized in congenics homozygous for the CBy Msh3 gene on a B6 background. The CAG stabilization was as dramatic as genetic deficiency of Msh2. The B6 and CBy Msh3 genes had identical promoters but differed in coding regions and showed strikingly different protein levels. B6 MSH3 variant protein is highly expressed and associated with CAG expansions, while the CBy MSH3 variant protein is expressed at barely detectable levels, associating with CAG stability. The DHFR protein, which is divergently transcribed from a promoter shared by the Msh3 gene, did not show varied levels between mouse strains. Thus, naturally occurring MSH3 protein polymorphisms are modifiers of CAG repeat instability, likely through variable MSH3 protein stability. Since evidence supports that somatic CAG instability is a modifier and predictor of disease, our data are consistent with the hypothesis that variable levels of CAG instability associated with polymorphisms of DNA repair genes may have prognostic implications for various repeat-associated diseases
Environmental Sampling for Spores of Bacillus anthracis
On November 11, 2001, following the bioterrorism-related anthrax attacks, the U.S. Postal Service collected samples at the Southern Connecticut Processing and Distribution Center; all samples were negative for Bacillus anthracis. After a patient in Connecticut died from inhalational anthrax on November 19, the center was sampled again on November 21 and 25 by using dry and wet swabs. All samples were again negative for B. anthracis. On November 28, guided by information from epidemiologic investigation, we sampled the site extensively with wet wipes and surface vacuum sock samples (using HEPA vacuum). Of 212 samples, 6 (3%) were positive, including one from a highly contaminated sorter. Subsequently B. anthracis was also detected in mail-sorting bins used for the patient’s carrier route. These results suggest cross-contaminated mail as a possible source of anthrax for the inhalational anthrax patient in Connecticut. In future such investigations, extensive sampling guided by epidemiologic data is imperative
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