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Search Results: 1 - 10 of 62311 matches for " Matthew David Riddle "
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Designing informal learning spaces using student perspectives
Matthew David Riddle,Kay Souter
Journal of Learning Spaces , 2012,
Abstract: This article describes the design of informal learning spaces at an Australian university that support students in the generation of knowledge. Recent learning space design projects at La Trobe have been informed by a number of pre-existing projects, including a small research project on student use of technologies, a national project on learning space design, and a significant curriculum renewal process at the university. It demonstrates the ways in which evidence based on student perspectives and principles developed through applied research in teaching and learning can inform real world learning space design projects in a higher education context.
Regionally Distinct Responses of Microglia and Glial Progenitor Cells to Whole Brain Irradiation in Adult and Aging Rats
Kun Hua, Matthew K. Schindler, Joseph A. McQuail, M. Elizabeth Forbes, David R. Riddle
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052728
Abstract: Radiation therapy has proven efficacy for treating brain tumors and metastases. Higher doses and larger treatment fields increase the probability of eliminating neoplasms and preventing reoccurrence, but dose and field are limited by damage to normal tissues. Normal tissue injury is greatest during development and in populations of proliferating cells but also occurs in adults and older individuals and in non-proliferative cell populations. To better understand radiation-induced normal tissue injury and how it may be affected by aging, we exposed young adult, middle-aged, and old rats to 10 Gy of whole brain irradiation and assessed in gray- and white matter the responses of microglia, the primary cellular mediators of radiation-induced neuroinflammation, and oligodendrocyte precursor cells, the largest population of proliferating cells in the adult brain. We found that aging and/or irradiation caused only a few microglia to transition to the classically “activated” phenotype, e.g., enlarged cell body, few processes, and markers of phagocytosis, that is seen following more damaging neural insults. Microglial changes in response to aging and irradiation were relatively modest and three markers of reactivity - morphology, proliferation, and expression of the lysosomal marker CD68- were regulated largely independently within individual cells. Proliferation of oligodendrocyte precursors did not appear to be altered during normal aging but increased following irradiation. The impacts of irradiation and aging on both microglia and oligodendrocyte precursors were heterogeneous between white- and gray matter and among regions of gray matter, indicating that there are regional regulators of the neural response to brain irradiation. By several measures, the CA3 region of the hippocampus appeared to be differentially sensitive to effects of aging and irradiation. The changes assessed here likely contribute to injury following inflammatory challenges like brain irradiation and represent important end-points for analysis in studies of therapeutic strategies to protect patients from neural dysfunction.
The Campaign: a case study in identity construction through performance
Matthew D. Riddle
Research in Learning Technology , 2009, DOI: 10.3402/rlt.v17i1.10864
Abstract: This article undertakes a detailed case study of The Campaign, a teaching and learning innovation in media and communications that uses an online educational role-play. The case study draws on the qualitative analysis of classroom observations, online communications and semi-structured interviews, employing an interpretive approach informed by models drawn from social theory and sociotechnical theory. Educational authors argue that online educational role-plays engage students in authentic learning, and represent an improvement over didactic teaching strategies. According to this literature, online role-play systems afford students the opportunity of acting and doing instead of only reading and listening. Literature in social theory and social studies of technology takes a different view of certain concepts such as performance, identity and reality. Models such as performative self constitution and actor network theory ask us to consider the constructed nature of identity and the roles of all of the actors, including the system itself. This article examines these concepts by addressing a series of research questions relating to identity formation and mediation, and suggests certain limitations of the situationist perspective in explaining the educational value of role-play systems.
Developing Engineering Model Cobra fiber positioners for the Subaru Telescope Prime Focus Spectrometer
Charles Fisher,Chaz Morantz,David Braun,Michael Seiffert,Hrand Aghazarian,Eamon Partos,Matthew King,Larry Hovland,Mark Schwochert,Joel Kaluzny,Christopher Capocasale,Andrew Houck,Johannes Gross,Dan Reiley,Peter Mao,Reed Riddle,Khanh Bui,David Henderson,Todd Haran,Rob Culhane,Daniele Piazza,Eric Walkama
Physics , 2014, DOI: 10.1117/12.2054700
Abstract: The Cobra fiber positioner is being developed by the California Institute of Technology (CIT) and the Jet Propulsion Laboratory (JPL) for the Prime Focus Spectrograph (PFS) instrument that will be installed at the Subaru Telescope on Mauna Kea, Hawaii. PFS is a fiber fed multi-object spectrometer that uses an array of Cobra fiber positioners to rapidly reconfigure 2394 optical fibers at the prime focus of the Subaru Telescope that are capable of positioning a fiber to within 5um of a specified target location. A single Cobra fiber positioner measures 7.7mm in diameter and is 115mm tall. The Cobra fiber positioner uses two piezo-electric rotary motors to move a fiber optic anywhere in a 9.5mm diameter patrol area. In preparation for full-scale production of 2550 Cobra positioners an Engineering Model (EM) version was developed, built and tested to validate the design, reduce manufacturing costs, and improve system reliability. The EM leveraged the previously developed prototype versions of the Cobra fiber positioner. The requirements, design, assembly techniques, development testing, design qualification and performance evaluation of EM Cobra fiber positioners are described here. Also discussed is the use of the EM build and test campaign to validate the plans for full-scale production of 2550 Cobra fiber positioners scheduled to begin in late-2014.
Role of PPARs in Radiation-Induced Brain Injury
Sriram Ramanan,Weiling Zhao,David R. Riddle,Mike E. Robbins
PPAR Research , 2010, DOI: 10.1155/2010/234975
Abstract: Whole-brain irradiation (WBI) represents the primary mode of treatment for brain metastases; about 200?000 patients receive WBI each year in the USA. Up to 50% of adult and 100% of pediatric brain cancer patients who survive >6 months post-WBI will suffer from a progressive, cognitive impairment. At present, there are no proven long-term treatments or preventive strategies for this significant radiation-induced late effect. Recent studies suggest that the pathogenesis of radiation-induced brain injury involves WBI-mediated increases in oxidative stress and/or inflammatory responses in the brain. Therefore, anti-inflammatory strategies can be employed to modulate radiation-induced brain injury. Peroxisomal proliferator-activated receptors (PPARs) are ligand-activated transcription factors that belong to the steroid/thyroid hormone nuclear receptor superfamily. Although traditionally known to play a role in metabolism, increasing evidence suggests a role for PPARs in regulating the response to inflammation and oxidative injury. PPAR agonists have been shown to cross the blood-brain barrier and confer neuroprotection in animal models of CNS disorders such as stroke, multiple sclerosis and Parkinson's disease. However, the role of PPARs in radiation-induced brain injury is unclear. In this manuscript, we review the current knowledge and the emerging insights about the role of PPARs in modulating radiation-induced brain injury. 1. Introduction PPARs are ligand-activated transcription factors that belong to the steroid/thyroid hormone superfamily of nuclear receptors [1, 2]. To date, three PPAR isotypes have been identified—PPAR (NR1C1), PPAR (NR1C2 or PPAR ), and PPAR (NR1C3) [3]. Each is encoded by a separate gene, and each has a unique tissue distribution pattern [4, 5]. PPARs regulate gene transcription by heterodimerizing with the retinoid X receptor (RXR) and binding to specific consensus sequences (termed PPAR response elements, PPREs) in the enhancer regions of genes [6]. PPREs consist of a direct repeat (DR) of the nuclear receptor hexameric recognition sequence AGGTCA separated by one or two nucleotides (DR-1 or DR-2) [6]. The protein structure of the PPAR isotypes reveals two well-characterized domains— a highly conserved DNA binding domain and a ligand-binding domain (LBD) that is less well conserved across the subtypes. Variation in the sequence of amino acids that line the ligand-binding pocket is a major determinant of ligand isotype specificity [7, 8]. In the absence of ligand binding, PPAR-RXR heterodimers are bound to corepressor proteins
Dedifferentiated chondrosarcoma arising in fibrous dysplasia: A case report and review of the current literature
Nicole MD Riddle,Hideko Yamauchi,Jamie T Caracciolo,David Johnson
Pathology and Laboratory Medicine International , 2009,
Abstract: Nicole MD Riddle1, Hideko Yamauchi2, Jamie T Caracciolo4, David Johnson2, G Douglas Letson2, Ardeshir Hakam1,3, Prudence V Smith1,2,3, Marilyn M Bui1,2,31Department of Pathology and Cell Biology, University of South Florida, Tampa, FL, USA; 2Department of Sarcoma, 3Department of Anatomic Pathology, 4Department of Radiology, Moffitt Cancer Center, Tampa, FL, USABackground: Fibrous dysplasia is an uncommon bone disease that has rare but clear potential for malignant transformation. The frequency is increased in polyostotic forms, McCune–Albright syndrome, Mazabraud’s syndrome, and previously irradiated sites. Rapidly progressing pain unrelated to trauma is the most concerning symptom. The early radiological features of sarcomatous transformation are moth-eaten or cystic areas of osteolysis, cortical destruction, and gradual formation of a soft tissue mass. The prognosis is unfavorable as most of the cases are in an advanced stage at the time of diagnosis.Methods: This case was diagnosed at a large cancer center in Florida. Pertinent clinical findings were obtained from chart review and inter-departmental consultation.Results: Histopathological examination revealed dysplastic lamellar bone with no osteoblastic rimming and “Chinese letter” shapes, areas composed of lobulated hyaline cartilage with mild to severe nuclear atypia, and areas of poorly differentiated cells with a spindled appearance, consistent with chondrosarcoma arising within fibrous dysplasia.Conclusions: Sarcomatous transformation of fibrous dysplasia is an uncommon occurrence, yet has significant importance for those with the disease. There may be difficulty with diagnosis given the symptoms and radiologic findings of benign fibrous dysplasia. We report a case of chondrosarcoma rising in fibrous dysplasia and review the current literature. This case is of interest due to the fact that the diagnosis of monostotic fibrous dysplasia was first made at the age of 59 and malignant transformation occurred within a decade with no history of trauma or radiation. This is an excellent example of how a change in symptoms without a history of trauma should be alarming to the clinician and warrants a thorough work-up for malignancy. To the best of our knowledge, this represents the second case of dedifferentiated chondrosarcoma within the English literature.Keywords: dedifferentiated chondrosarcoma, fibrous dysplasia, malignant transformation, McCune–Albright syndrome, Mazabraud’s syndrome
PM noise of a 40 GHz air-dielectric cavity oscillator
Archita Hati,Craig W. Nelson,B. Riddle,David A. Howe
Physics , 2014,
Abstract: We describe the design of a low-phase-modulated (PM) noise, 40 GHz oscillator that uses a conventional air-dielectric cavity resonator as a frequency discriminator to improve the PM noise of a commercial 10 GHz dielectric resonator oscillator (DRO) frequency multiplied by four. The main features of this design incorporate (1) unloaded cavity quality factor (Q) of 30,000, (2) high coupling coefficient, (3) large carrier suppression by use of interferometric signal processing, (4) large operating signal power of approximately 1 watt (W), and (5) relatively small size. In addition, we report the PM noise of several Ka-band components.
As Old as the Hills: Montane Scorpions in Southwestern North America Reveal Ancient Associations between Biotic Diversification and Landscape History
Robert W. Bryson, Brett R. Riddle, Matthew R. Graham, Brian Tilston Smith, Lorenzo Prendini
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0052822
Abstract: Background The age of lineages has become a fundamental datum in studies exploring the interaction between geological transformation and biotic diversification. However, phylogeographical studies are often biased towards lineages that are younger than the geological features of the landscapes they inhabit. A temporally deeper historical biogeography framework may be required to address episodes of biotic diversification associated with geologically older landscape changes. Signatures of such associations may be retained in the genomes of ecologically specialized (stenotopic) taxa with limited vagility. In the study presented here, genetic data from montane scorpions in the Vaejovis vorhiesi group, restricted to humid rocky habitats in mountains across southwestern North America, were used to explore the relationship between scorpion diversification and regional geological history. Results Strong phylogeographical signal was evident within the vorhiesi group, with 27 geographically cohesive lineages inferred from a mitochondrial phylogeny. A time-calibrated multilocus species tree revealed a pattern of Miocene and Pliocene (the Neogene period) lineage diversification. An estimated 21 out of 26 cladogenetic events probably occurred prior to the onset of the Pleistocene, 2.6 million years ago. The best-fit density-dependent model suggested diversification rate in the vorhiesi group gradually decreased through time. Conclusions Scorpions of the vorhiesi group have had a long history in the highlands of southwestern North America. Diversification among these stenotopic scorpions appears to have occurred almost entirely within the Neogene period, and is temporally consistent with the dynamic geological history of the Basin and Range, and Colorado Plateau physiographical provinces. The persistence of separate lineages at small spatial scales suggests that a combination of ecological stenotopy and limited vagility may make these scorpions particularly valuable indicators of geomorphological evolution.
Guillan-Barre Syndrome in a Patient with Uncontrolled Diabetes and Severe Peripheral Neuropathy  [PDF]
David Alex Kranc, David Meurer, Matthew F. Ryan
Open Journal of Emergency Medicine (OJEM) , 2018, DOI: 10.4236/ojem.2018.62005
Abstract: The complications of diabetes are frequently encountered in the Emergency Department. In contrast, Guillan-Barre Syndrome (GBS) is a relatively rare diagnosis requiring a high index of suspicion which can cause significant morbidity and mortality if not recognized and properly treated. GBS is an acquired condition which is usually preceded by a viral upper respiratory or gastrointestinal (GI) illness which can cause peripheral weakness and potentially diaphragmatic paralysis leading to life-threatening respiratory failure. Herein, we present a case of a 57-year-old male with a history of poorly-controlled diabetes who presented with both sensory and motor weakness of the distal upper and lower extremities; the patient was ultimately diagnosed with Guillan-Barre syndrome. This case illustrated an uncommon disease process that was initially mistaken for an extremely common disease both of which require very different management. This illustrative case is important to the emergency medicine physician because quick identification can stave off untoward complications and increased morbidity and mortality of GBS including respiratory distress and airway emergencies.
Self Reported Incidence and Morbidity of Acute Respiratory Illness among Deployed U.S. Military in Iraq and Afghanistan
Bryony W. Soltis, John W. Sanders, Shannon D. Putnam, David R. Tribble, Mark S. Riddle
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006177
Abstract: Background Historically, respiratory infections have had a significant impact on U.S. military missions. Deployed troops are particularly at high risk due to close living conditions, stressful work environments and increased exposure to pathogens. To date, there are limited data available on acute respiratory illness (ARI) among troops deployed in support of ongoing military operations, specifically Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF). Methods Using self-report data from two sources collected from troops deployed to Iraq, Afghanistan and the surrounding region, we analyzed incidence and risk factors for ARI. Military personnel on mid-deployment Rest & Recuperation (R&R) or during redeployment were eligible to participate in the voluntary self-report survey. Results Overall, 39.5% reported having at least one ARI. Of these, 18.5% sought medical care and 33.8% reported having decreased job performance. The rate of self-reported ARI was 15 episodes per 100 person-months among those taking the voluntary survey, and 24.7 episodes per 100 person-months among those taking the clinic health questionnaire. Negative binomial regression analysis found female sex, Navy branch of service and lack of flush toilets to be independently associated with increased rates of ARI. Deployment to OIF, increasing age and higher rank were also positively associated with ARI risk. Conclusions The overall percentage of deployed military personnel reporting at least one acute respiratory illness decreased since earlier parts of OIF/OEF. However, the reported effect on job performance increased tremendously. The most important factors associated with increased respiratory infection are female sex, Navy branch of service, lack of improved latrine facilities, deployment to OIF, increasing age and higher rank.
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