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Search Results: 1 - 10 of 1886 matches for " Leon Grayfer "
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Immune Evasion Strategies of Ranaviruses and Innate Immune Responses to These Emerging Pathogens
Leon Grayfer,Francisco De Jesús Andino,Guangchun Chen,Gregory V. Chinchar,Jacques Robert
Viruses , 2012, DOI: 10.3390/v4071075
Abstract: Ranaviruses (RV, Iridoviridae) are large double-stranded DNA viruses that infect fish, amphibians and reptiles. For ecological and commercial reasons, considerable attention has been drawn to the increasing prevalence of ranaviral infections of wild populations and in aquacultural settings. Importantly, RVs appear to be capable of crossing species barriers of numerous poikilotherms, suggesting that these pathogens possess a broad host range and potent immune evasion mechanisms. Indeed, while some of the 95–100 predicted ranavirus genes encode putative evasion proteins (e.g., vIFα, vCARD), roughly two-thirds of them do not share significant sequence identity with known viral or eukaryotic genes. Accordingly, the investigation of ranaviral virulence and immune evasion strategies is promising for elucidating potential antiviral targets. In this regard, recombination-based technologies are being employed to knock out gene candidates in the best-characterized RV member, Frog Virus (FV3). Concurrently, by using animal infection models with extensively characterized immune systems, such as the African clawed frog, Xenopus laevis, it is becoming evident that components of innate immunity are at the forefront of virus-host interactions. For example, cells of the macrophage lineage represent important combatants of RV infections while themselves serving as targets for viral infection, maintenance and possibly dissemination. This review focuses on the recent advances in the understanding of the RV immune evasion strategies with emphasis on the roles of the innate immune system in ranaviral infections.
Fish and Mammalian Phagocytes Differentially Regulate Pro-Inflammatory and Homeostatic Responses In Vivo
Aja M. Rieger, Jeffrey D. Konowalchuk, Leon Grayfer, Barbara A. Katzenback, Jeffrey J. Havixbeck, Moira D. Kiemele, Miodrag Belosevic, Daniel R. Barreda
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047070
Abstract: Phagocytosis is a cellular mechanism that is important to the early induction of antimicrobial responses and the regulation of adaptive immunity. At an inflammatory site, phagocytes serve as central regulators for both pro-inflammatory and homeostatic anti-inflammatory processes. However, it remains unclear if this is a recent evolutionary development or whether the capacity to balance between these two seemingly contradictory processes is a feature already displayed in lower vertebrates. In this study, we used murine (C57BL/6) and teleost fish (C. auratus) in vitro and in vivo models to assess the evolutionary conservation of this dichotomy at a site of inflammation. At the level of the macrophage, we found that teleost fish already displayed divergent pro-inflammatory and homeostatic responses following internalization of zymosan or apoptotic bodies, respectively, and that these were consistent with those of mice. However, fish and mice displayed significant differences in vivo with regards to the level of responsiveness to zymosan and apoptotic bodies, the identity of infiltrating leukocytes, their rate of infiltration, and the kinetics and strength of resulting antimicrobial responses. Unlike macrophages, significant differences were identified between teleost and murine neutrophilic responses. We report for the first time that activated murine, but not teleost neutrophils, possess the capacity to internalize apoptotic bodies. This internalization translates into reduction of neutrophil ROS production. This may play an important part in the recently identified anti-inflammatory activity that mammalian neutrophils display during the resolution phase of inflammation. Our observations are consistent with continued honing of inflammatory control mechanisms from fish to mammals, and provide added insights into the evolutionary path that has resulted in the integrated, multilayered responses that are characteristic of higher vertebrates.
A Wavelet Multigrid Method Using Symmetric Biorthogonal Wavelets  [PDF]
Doreen De Leon
American Journal of Computational Mathematics (AJCM) , 2013, DOI: 10.4236/ajcm.2013.32021
Abstract:

In [1], the author introduced a wavelet multigrid method that used the wavelet transform to define the coarse grid, interpolation, and restriction operators for the multigrid method. In this paper, we modify the method by using symmetric biorthogonal wavelet transforms to define the requisite operators. Numerical examples are presented to demonstrate the effectiveness of the modified wavelet multigrid method for diffusion problems with highly oscillatory coefficients, as well as for advection-diffusion equations in which the advection is moderately dominant.

Relativity Current Paradigm with Unresolved Anomalies  [PDF]
Alfonso Leon Guillen Gomez
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.56047
Abstract:

When a theory, as the general relativity, linked to special relativity, is foundation of a scientific paradigm, through normal science and academy, scientifics, professionals, professors, students and journals of that scientific community, the paradigm, it self-sustains and reproduces. Thus, the research is obligated and limited to apply the model existent of the paradigm to formulate problems and solve them, without searching new discoveries. This self-protection of the paradigm causes it to end its cycle of life, only after a long time, until that arise unresolved anomalies, some presents since origin, that they finally cause its change by other new paradigm. In this work, we study the most important anomalies that are part of the foundations of general relativity with the goal of promoting the call period of transition that is previous to scientific revolution. We use critical analysis method for rereading the general relativity, from the perspective of the history of science and philosophy of science. We find, the structural and complex anomaly of general relativity based on metaphysical spacetime that produces the metaphysics replaces physics. Also, two internal anomalies their direct consequences. These are: matter curves metaphysical spacetime, and metaphysical spacetime determines the geodesic motion of physical matter. We conclude that general relativity has no valid physical concept of spacetime, therefore of gravity. For these reasons, a new paradigm is needed.

Inferring Locations of Mobile Devices from Wi-Fi Data  [PDF]
Leon Wu, Ying Zhu
Intelligent Information Management (IIM) , 2015, DOI: 10.4236/iim.2015.72006
Abstract: Mobile phones are becoming a primary platform for information access. A major aspect of ubiquitous computing is context-aware applications which collect information about the environment that the user is in and use this information to provide better service and improve user experience. Location awareness makes certain applications possible, e.g., recommending nearby businesses and tracking estimated routes. An Android application is able to collect useful Wi-Fi information without registering a location listener with a network-based provider. We passively collected the data of the IDs of Wi-Fi access points and the received signal strengths. We developed and implemented an algorithm to analyse the data; and designed heuristics to infer the location of the device over time—all without ever connecting to the network thus maximally preserving the privacy of the user.
Growing a Kerr Black Hole  [PDF]
Leon F. Phillips
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.613181
Abstract: Growth of a black hole requires the participation of a near-by accretion disk if it is to occur at a significant rate. The Kerr solution of Einstein’s equation is a vacuum solution, but the center of a realistic Kerr black hole is not a vacuum, so the predicted disk singularity does not exist. Instead, the center of a black hole is occupied by an ultra-dense, spheroidal core whose diameter is greater than that of the theoretical disk singularity. The surface of a black hole’s core is continually bombarded by energetic particles from the external universe. Hence the cold remnant of a gravitationally-collapsed star that has often been assumed to be present at the center of a black hole must be replaced conceptually by a quark-gluon plasma whose temperature is of the order of 1012 K or more. The gravitational potential well of a black hole is extremely deep (TeV), but the number of discrete energy levels below the infinite-red-shift surface is finite. Information can be conveyed to observers in the external universe by thermally-excited fermions that escape from levels near the top of a black hole potential well.
Transition Metal Trichalcogenides as Novel Layered Nano Species
Fedorov V.E.,Artemkina S.B.,Grayfer E.D.,Mironov Yu.V.
Proceedings of the International Conference Nanomaterials : Applications and Properties , 2013,
Abstract: In search for new materials for nanoelectronics, many efforts have been put into development of chemistry and physics of graphene, and, more recently, of other inorganic layered compounds having a bandgap (h-BN, MoS2 etc.). Here we introduce a new view on the family of transition metal trichalcogenides MQ3 (M=Ti, Zr, Nb, Ta; Q=S, Se), which were earlier considered as quasi-one-dimensional systems, and demonstrate that they also may be regarded as layered species suitable for exfoliation by a chemical method. Stable, concentrated colloidal dispersions of high-quality crystalline NbS3 and NbSe3 nanoribbons down to mono- and few-layer-thick are prepared by ultrasonic treatment of the bulk compound in several common organic solvents (DMF, NMP, CH3CN, iPrOH, H2O/EtOH). The dispersions and thin films prepared from them by vacuum filtration or spraying are characterized by a set of physical-chemical methods. Current-voltage characteristics of the NbS3 films show that charge carrier mobility is as high as 1200 – 2400 cm2V-1s-1, exceeding that of MoS2 and making NbQ3 promising potential candidates for field-effect transistors.
Teachers’ Instructional Competence on Students’ Comprehension Skills and Critical Thinking Ability  [PDF]
Ethel de Leon-Abao
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.24037
Abstract: Reading is a challenge and an opportunity to every person’s daily undertaking. If its ultimate aim is to develop critical thinking, then it has to be inculcated in the basic education. Observably, there is a prevailing issue on the low performance of students in content areas owing to their lack of comprehension. It is therefore the purpose of this study to determine how the teachers’ instructional competence influences the intermediate students’ comprehension skills as well as their critical thinking ability. Utilizing the normative-evaluative method, findings revealed that the intermediate students obtained an above average performance in following Directions. This reveals that the students are generally obedient. They are conscious of applying the skill in carrying out their varied activities/responsibilities because according to them careful compliance to standards and the like, engenders peace and order. On the other hand, both groups performed below average in Predicting Outcomes and Drawing Inferences respectively. This obviously denotes inadequacy in making intelligent guesses which are paramount in decision making. Since reading is significant to success basically in an academic undertaking, the teachers’ instructional competence as reflected in the findings is highly instrumental in the development of students’ comprehension skills and critical thinking as these would eventually lead them to function effectively in society.
Difficult-to-Treat-Depression and GPs’ Role: Perceptions of Psychiatry Registrars  [PDF]
Kay M. Jones, Leon Piterman
Open Journal of Psychiatry (OJPsych) , 2014, DOI: 10.4236/ojpsych.2014.44037
Abstract: Introduction: For patients, GPs are the most accessible medical resource in the community and are the gatekeepers to other community resources including psychiatrists. Qualifying as a psychiatrist in Australia involves completing a five-year training program that includes rotations in hospitals and community settings. The aims of this research were to 1) explore psychiatry registrars’ perceptions of difficult-to-treat-depression (DTTD) and 2) what they thought about the GPs’ role in this regard. Methods: A semi-structured interview schedule comprising six questions was used; 10 psychiatry registrars (6 females, 4 males) participated in a one-and-half-hour focus group. All were in their final year of training and undertaking a training post in a public hospital in Melbourne, Australia. Data were analysed using the Framework Method. Findings: Similar to GPs and GP trainees, psychiatry registrars’ perceptions and understanding of DTTD varied. While acknowledging limited experience in diagnosis and management, issues important to them included the utility of labels such as DTTD; patients distressed because of another diagnosis, substance abuse and/or life problems, the importance of accurate histories and notes, cost and limited availability of services particularly in the private sector, prescribing regimens, referring to allied health professionals, and suggesting/prescribing non pharmacological and/or complementary treatment. Also what was of concern was communication, both between health professionals and between health professionals and patients. Consensus was that treating depression in general practice is one of the hardest things for GPs to manage but there was value in using mental health plans. Discussion and Conclusion: While this cohort was small in number with limited experience, this study is the first to contribute to the literature that provides some insight into psychiatry registrars’ experiences and perceptions of DTTD. Outcomes may have implications for thepsychiatry training program and GPs who diagnose and manage patients with mental health problems.
Difficult-to-Treat-Depression and GPs’ Role: Perceptions of Psychologists  [PDF]
Kay M. Jones, Leon Piterman
Open Journal of Psychiatry (OJPsych) , 2015, DOI: 10.4236/ojpsych.2015.51005
Abstract: Introduction: Since the Australian Government introduced the “Better Access to Mental Health Services” program in 2006, psychiatrists, psychologists and general practitioners (GPs) have become increasingly involved in service provision for people seeking help with mental health problems. The aim of this research was to a) explore psychologists’ perceptions of difficult to treat depression (DTTD) and b) explore what they thought about the GPs’ role in managing these patient given that most patients are referred to psychologist by GPs. Methods: A previously developed semi-structured interview schedule comprising six questions was used. Seven psychologists participated in a focus group held in Melbourne. Data were analysed using the framework method. Findings, including Discussion: While psychologists understood the term DTTD it was suggested that using different terms may limit understanding between health professionals. Rather than diagnosing, psychologists were more likely to conduct further assessment contextually to confirm GPs’ diagnosis. Communication with GPs was important, particularly when managing “long-term” and suicidal patients. Management included cognitive and behavioural interventions and referring to other mental health services, psychiatrists and/or other allied health professionals. Referral to psychiatrists could be difficult because of limited availability and for some patients, prohibitive costs. Although psychologists discussed non-pharmacological and/or complementary treatment options with patients, they were more likely to rely on GPs to discuss/prescribe these options. Conclusion: While generalisability may be limited, this study is the first to document some understanding of psychologists perceptions of DTTD and the importance of GPs and other health professionals’ role in managing this patient cohort.
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