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Search Results: 1 - 10 of 12090 matches for " Matthew Kramer "
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Replication of West Nile virus, Rabensburg lineage in mammalian cells is restricted by temperature
Aliota Matthew T,Kramer Laura D
Parasites & Vectors , 2012, DOI: 10.1186/1756-3305-5-293
Abstract: Background The genus Flavivirus currently consists of approximately 80 single-strand positive-sense RNA viruses. These replicate in a range of hosts including myriad vertebrate, insect, and tick species. As a consequence of this broad host range, the majority of flaviviruses can be propagated in most vertebrate and insect cell cultures. This ability to infect arthropods and vertebrates usually is essential for maintenance of these viruses in nature. But recently, there has been the discovery of a number of flaviviruses that infect mosquitoes but not vertebrates. It remains largely unknown why certain flaviviruses infect vertebrates and mosquitoes while others infect mosquitoes or vertebrates exclusively. Methods Here, we initiated in vitro host range studies of Rabensburg virus (RABV), an intermediate between the mosquito-specific and horizontally transmitted flaviviruses, to provide information on the factor(s) that underlie the varying host range of flaviviruses. RABV is an intermediate between the mosquito-specific and horizontally transmitted flaviviruses because it does not infect mammalian or avian cell cultures, house sparrows, or chickens, but it does share genetic characteristics with the Japanese Encephalitis serogroup of flaviviruses. Results In vitro growth kinetic assays revealed the complete abrogation of RABV growth on Vero and E6 cells incubated at temperatures 35°C and higher, but surprisingly RABV infected, replicated efficiently, and displayed overt cytopathic effects (CPE) on Vero and E6 cell cultures incubated below 35°C. In contrast, RABV was fully viable, replicated efficiently, and displayed overt CPE on C6/36 cells incubated at 28°C or 37°C, thus implicating temperature as an important factor limiting the host range of RABV. Conclusions These data are critical for further study to more fully identify the determinants that mediate the evolution of biological transmission among flaviviruses. It also will be useful for studies that look to provide a comprehensive molecular definition of flavivirus-host cell interactions. And it will provide a cadre of information to design wet lab experiments to investigate the genetic changes that facilitate host switching, which may lead to new vertebrate pathogens or transmission pathways.
Probiotics in the Treatment of Chronic Rhinoconjunctivitis and Chronic Rhinosinusitis
Matthias F. Kramer,Matthew D. Heath
Journal of Allergy , 2014, DOI: 10.1155/2014/983635
Abstract: Chronic rhinitis and rhinosinusitis (CRS) are relevant health conditions affecting significant percentages of the western population. They are frequently coexisting and aggravating diseases. Both are chronic, noninfectious, and inflammatory conditions sharing to a certain extent important pathophysiologic similarities. Beneficial effects of probiotics are long known to mankind. Research is beginning to unravel the true nature of the human microbiome and its interaction with the immune system. The growing prevalence of atopic diseases in the developed world led to the proposition of the “hygiene hypothesis.” Dysbiosis is linked to atopic diseases; probiotic supplementation is able to alter the microbiome and certain probiotic strains have immunomodulatory effects in favour of a suppression of Th-2 and stimulation of a Th1 profile. This review focuses on randomized, double-blind, placebo-controlled trials investigating clinical parameters in the treatment of chronic rhinitis and CRS. An emerging number of publications demonstrate beneficial effects using probiotics in clinical double-blind placebo-controlled (dbpc) trials in allergic rhinitis (AR). Using probiotics as complementary treatment options in AR seems to be a promising concept although the evidence is of a preliminary nature to date and more convincing trials are needed. There are no current data to support the use of probiotics in non-AR or CRS. 1. Chronic Rhinoconjunctivitis and Chronic Rhinosinusitis ARIA guideline defines rhinitis as a chronic inflammatory disease of the nose resulting in nasal symptoms including nasal obstruction, sneezing, and anterior or posterior rhinorrhea (occurring during two or more consecutive days for more than one hour) [1]. Allergic rhinitis (AR) is the most common form of noninfectious, chronic rhinitis affecting more than 25% percent of the European population [1, 2]. It is characterized as an eosinophilic, IgE-mediated, Th-2 dominated immune disorder. “Local allergic rhinitis” describes a condition of local allergen-specific IgE production in the nose. Prevalence data are estimated to lay between 47% and 62.5% of patients with perennial and seasonal symptoms. Interestingly, this condition is described to precede a “classic” AR [3]. Prevalence data about nonallergic forms of chronic, noninfectious rhinitis are rare. They are estimated to be almost as high as AR [1]. Non-AR includes a long list of potential causes. However, the idiopathic form remains the most frequent [4]. Although non-AR is per exclusion not a type-I allergy it resembles often the same
A correction to the enhanced bottom drag parameterisation of tidal turbines
Stephan C Kramer,Matthew D Piggott
Computer Science , 2015,
Abstract: Hydrodynamic modelling is an important tool for the development of tidal stream energy projects. Many hydrodynamic models incorporate the effect of tidal turbines through an enhanced bottom drag. In this paper we show that although for coarse grid resolutions (kilometre scale) the resulting force exerted on the flow agrees well with the theoretical value, the force starts decreasing with decreasing grid sizes when these become smaller than the length scale of the wake recovery. This is because the assumption that the upstream velocity can be approximated by the local model velocity, is no longer valid. Using linear momentum actuator disc theory however, we derive a relationship between these two velocities and formulate a correction to the enhanced bottom drag formulation that consistently applies a force that remains closed to the theoretical value, for all grid sizes down to the turbine scale. In addition, a better understanding of the relation between the model, upstream, and actual turbine velocity, as predicted by actuator disc theory, leads to an improved estimate of the usefully extractable energy. We show how the corrections can be applied (demonstrated here for the models MIKE 21 and Fluidity) by a simple modification of the drag coefficient.
Delta Opioid activation of the Mitogen-activated protein kinase cascade does not require transphosphorylation of Receptor Tyrosine Kinases
Kramer H Kenneth,Onoprishvili Irma,Andria Matthew L,Hanna Kayane
BMC Pharmacology , 2002, DOI: 10.1186/1471-2210-2-5
Abstract: Background In this study, we investigated the mechanism(s) by which delta opioids induce their potent activation of extracellular signal-regulated protein kinases (ERKs) in different cell lines expressing the cloned δ-opioid receptor (δ-OR). While it has been known for some time that OR stimulation leads to the phosphorylation of both ERK isoforms, the exact progression of events has remained elusive. Results Our results indicate that the transphosphorylation of an endogenous epidermal growth factor receptor (EGFR) in the human embryonic kidney (HEK-293) cell line does not occur when co-expressed δ-ORs are stimulated by the δ-opioid agonist, D-Ser-Leu-enkephalin-Thr (DSLET). Moreover, neither pre-incubation of cultures with the selective EGFR antagonist, AG1478, nor down-regulation of the EGFR to a point where EGF could no longer activate ERKs had an inhibitory effect on ERK activation by DSLET. These results appear to rule out any structural or catalytic role for the EGFR in the δ-opioid-mediated MAPK cascade. To confirm these results, we used C6 glioma cells, a cell line devoid of the EGFR. In δ-OR-expressing C6 glioma cells, opioids produce a robust phosphorylation of ERK 1 and 2, whereas EGF has no stimulatory effect. Furthermore, antagonists to the RTKs that are endogenously expressed in C6 glioma cells (insulin receptor (IR) and platelet-derived growth factor receptor (PDGFR)) were unable to reduce opioid-mediated ERK activation. Conclusion Taken together, these data suggest that the transactivation of resident RTKs does not appear to be required for OR-mediated ERK phosphorylation and that the tyrosine-phosphorylated δ-OR, itself, is likely to act as its own signalling scaffold.
High time-resolution observations of the Vela pulsar
Simon Johnston,Willem van Straten,Michael Kramer,Matthew Bailes
Physics , 2001, DOI: 10.1086/319154
Abstract: We present high time resolution observations of single pulses from the Vela pulsar (PSR B0833-45) made with a baseband recording system at observing frequencies of 660 and 1413 MHz. We have discovered two startling features in the 1413 MHz single pulse data. The first is the presence of giant micro-pulses which are confined to the leading edge of the pulse profile. One of these pulses has a peak flux density in excess of 2500 Jy, more than 40 times the integrated pulse peak. The second new result is the presence of a large amplitude gaussian component on the trailing edge of the pulse profile. This component can exceed the main pulse in intensity but is switched on only relatively rarely. Fluctutation spectra reveal a possible periodicity in this feature of 140 pulse periods. Unlike the rest of the profile, this component has low net polarization and emits predominantly in the orthogonal mode. This feature appears to be unique to the Vela pulsar. We have also detected microstructure in the Vela pulsar for the first time. These same features are present in the 660 MHz data. We suggest that the full width of the Vela pulse profile might be as large as 10 ms but that the conal edges emit only rarely.
Design optimisation and resource assessment for tidal-stream renewable energy farms using a new continuous turbine approach
Simon W. Funke,Stephan C. Kramer,Matthew D. Piggott
Mathematics , 2015,
Abstract: This paper presents a new approach for optimising the design of tidal stream turbine farms. In this approach, the turbine farm is represented by a turbine density function that specifies the number of turbines per unit area and an associated continuous locally-enhanced bottom friction field. The farm design question is formulated as a mathematical optimisation problem constrained by the shallow water equations and solved with efficient, gradient-based optimisation methods. The resulting method is accurate, computationally efficient, allows complex installation constraints, and supports different goal quantities such as to maximise power or profit. The outputs of the optimisation are the optimal number of turbines, their location within the farm, the overall farm profit, the farm's power extraction, and the installation cost. We demonstrate the capabilities of the method on a validated numerical model of the Pentland Firth, Scotland. We optimise the design of four tidal farms simultaneously, as well as individually, and study how farms in close proximity may impact upon one another.
Early Childhood Education: Difficulties Creating and Changing Daily Practice  [PDF]
Sonia Kramer
Creative Education (CE) , 2014, DOI: 10.4236/ce.2014.56048

This paper is based on research carried out with children and adults at early childhood education institutions in Rio de Janeiro, Brazil. The research goals were to identify interactions between adults and children and to rethink pedagogical practice. The theoretical-methodological framework was based on language and culture studies, the sociology of childhood and anthropology. After studying children and adults in different contexts and early childhood education public policies and practice, the results present challenges of changing and creating early education practices in difficult contexts, especially with regard to the creation and use of spaces intended for children. This is the focus of the text, which is structured in three sections. Section one presents the theoretical and methodological issues. The second section analyzes three case studies developed in public pre-schools situated in different cities in the state of Rio de Janeiro. Section three presents conclusions and priorities for intervention and change concerning children, adults and their interactions.

Training Needs of International Medical Graduates [IMGs] in Psychiatry  [PDF]
Milton Kramer
Open Journal of Psychiatry (OJPsych) , 2014, DOI: 10.4236/ojpsych.2014.44036
Abstract: The potential shortage of psychiatrists over the next 5 - 10 years has focused attention on the need to recruit more IMGs to fill the needs rather than use nurse practitioners or physician assistants. IMGs make up about 1/3 of first year psychiatry residents. These individuals have been found to provide services to the poor, the elderly and the psychotic. The quality of their medical work has been found to be satisfactory. The training needs of these physicians require an understanding on the part of their teachers that they come from cultures with different values that we have. The extended families of these primarily Asian residents clash with our strong commitment to individualism. It leads to a We-self rather than our I-Self. This difference coupled with the stress of leaving to come to a new culture is a great stress. Their exposure to psychiatry has been limited. They request and need more interview demonstration and practice, ore feedback and examinations. They should have help in accent reduction. They should be exposed to the working of the hospital by sitting on departmental and hospital committees. The faculty should extend their social opportunities and work as mentors on joint projects. Courses on the history of American culture should be taught. Psychotherapy for them should be encouraged as well as teaching medical ethics. They must become the major educational concern for the department that they are in.
Security and Privacy Qualities of Medical Devices: An Analysis of FDA Postmarket Surveillance
Daniel B. Kramer, Matthew Baker, Benjamin Ransford, Andres Molina-Markham, Quinn Stewart, Kevin Fu, Matthew R. Reynolds
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040200
Abstract: Background Medical devices increasingly depend on computing functions such as wireless communication and Internet connectivity for software-based control of therapies and network-based transmission of patients’ stored medical information. These computing capabilities introduce security and privacy risks, yet little is known about the prevalence of such risks within the clinical setting. Methods We used three comprehensive, publicly available databases maintained by the Food and Drug Administration (FDA) to evaluate recalls and adverse events related to security and privacy risks of medical devices. Results Review of weekly enforcement reports identified 1,845 recalls; 605 (32.8%) of these included computers, 35 (1.9%) stored patient data, and 31 (1.7%) were capable of wireless communication. Searches of databases specific to recalls and adverse events identified only one event with a specific connection to security or privacy. Software-related recalls were relatively common, and most (81.8%) mentioned the possibility of upgrades, though only half of these provided specific instructions for the update mechanism. Conclusions Our review of recalls and adverse events from federal government databases reveals sharp inconsistencies with databases at individual providers with respect to security and privacy risks. Recalls related to software may increase security risks because of unprotected update and correction mechanisms. To detect signals of security and privacy problems that adversely affect public health, federal postmarket surveillance strategies should rethink how to effectively and efficiently collect data on security and privacy problems in devices that increasingly depend on computing systems susceptible to malware.
West Nile Virus Epidemics in North America Are Driven by Shifts in Mosquito Feeding Behavior
A. Marm Kilpatrick,Laura D. Kramer,Matthew J. Jones,Peter P. Marra,Peter Daszak
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0040082
Abstract: West Nile virus (WNV) has caused repeated large-scale human epidemics in North America since it was first detected in 1999 and is now the dominant vector-borne disease in this continent. Understanding the factors that determine the intensity of the spillover of this zoonotic pathogen from birds to humans (via mosquitoes) is a prerequisite for predicting and preventing human epidemics. We integrated mosquito feeding behavior with data on the population dynamics and WNV epidemiology of mosquitoes, birds, and humans. We show that Culex pipiens, the dominant enzootic (bird-to-bird) and bridge (bird-to-human) vector of WNV in urbanized areas in the northeast and north-central United States, shifted its feeding preferences from birds to humans by 7-fold during late summer and early fall, coinciding with the dispersal of its preferred host (American robins, Turdus migratorius) and the rise in human WNV infections. We also show that feeding shifts in Cx. tarsalis amplify human WNV epidemics in Colorado and California and occur during periods of robin dispersal and migration. Our results provide a direct explanation for the timing and intensity of human WNV epidemics. Shifts in feeding from competent avian hosts early in an epidemic to incompetent humans after mosquito infection prevalences are high result in synergistic effects that greatly amplify the number of human infections of this and other pathogens. Our results underscore the dramatic effects of vector behavior in driving the transmission of zoonotic pathogens to humans.
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