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Search Results: 1 - 10 of 7287 matches for " Samuel Newton "
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On the Stability of Our Universe  [PDF]
Marcelo Samuel Berman, Newton C. A. da Costa
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.329156
Abstract: We argue that the Robertson-Walker’s Universe is a zero-energy stable one, even though it may possess a rotational state besides expansion.
On the Stability of Our Universe
Marcelo Samuel Berman,Newton C. A. da Costa
Physics , 2010, DOI: 10.4236/jmp.2012.329156.
Abstract: We argue that the Robertson-Walker's Universe is a zero-energy stable one, even though it may possess a rotational state besides expansion.
Comparative genomics of proteins involved in RNA nucleocytoplasmic export
Mariana Serpeloni, Newton M Vidal, Samuel Goldenberg, Andréa R ávila, Federico G Hoffmann
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-7
Abstract: Our objective was to reconstruct the evolutionary history of the different RNA export pathways across eukaryotes. To do so, we screened an array of eukaryotic genomes for the presence of homologs of the proteins involved in RNA export in Metazoa and Fungi, using human and yeast proteins as queries.Our genomic comparisons indicate that the basic components of the RanGTP-dependent RNA pathways are conserved across eukaryotes, and thus we infer that these are traceable to the last eukaryotic common ancestor (LECA). On the other hand, several of the proteins involved in RanGTP-independent mRNA export pathways are less conserved, which would suggest that they represent innovations that appeared later in the evolution of eukaryotes.Our analyses suggest that the LECA possessed the basic components of the different RNA export mechanisms found today in opisthokonts, and that these mechanisms became more specialized throughout eukaryotic evolution.Protein synthesis in all living cells involves the transcription of DNA into messenger RNA (mRNA) and its subsequent translation into polypeptides. In prokaryotes, transcription and translation are physically and temporally linked, and each mRNA molecule is translated by the ribosomes as it is transcribed. By contrast, in eukaryotes transcription and mRNA processing are physically and temporally separated from translation by the nuclear membrane. This separation is hypothesized to have been a major factor in the emergence of the nuclear membrane [1]. As a result of the establishment of the nuclear membrane, the different RNA species involved in protein synthesis such as mRNAs, ribosomal RNAs (rRNAs), and transfer RNAs (tRNAs), need to be shuttled from the nucleus to the cytoplasm. The general model of RNA export involves exportins as transport receptors that carry RNA through the nuclear pore complex (NPC) in a RanGTP-dependent manner [2]. In Metazoa and Fungi, the nuclear export of most RNA species, such as microRNAs (miRNAs), rRNA
Isolation of Highly Suppressive CD25+FoxP3+ T Regulatory Cells from G-CSF-Mobilized Donors with Retention of Cytotoxic Anti-Viral CTLs: Application for Multi-Functional Immunotherapy Post Stem Cell Transplantation
Edward R. Samuel, Lorea Beloki, Katy Newton, Stephen Mackinnon, Mark W. Lowdell
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0085911
Abstract: Previous studies have demonstrated the effective control of cytomegalovirus (CMV) infections post haematopoietic stem cell transplant through the adoptive transfer of donor derived CMV-specific T cells (CMV-T). Strategies for manufacturing CMV immunotherapies has involved a second leukapheresis or blood draw from the donor, which in the unrelated donor setting is not always possible. We have investigated the feasibility of using an aliquot of the original G-CSF-mobilized graft as a starting material for manufacture of CMV-T and examined the activation marker CD25 as a targeted approach for identification and isolation following CMVpp65 peptide stimulation. CD25+ cells isolated from G-CSF-mobilized apheresis revealed a significant increase in the proportion of FoxP3 expression when compared with conventional non-mobilized CD25+ cells and showed a superior suppressive capacity in a T cell proliferation assay, demonstrating the emergence of a population of Tregs not present in non-mobilized apheresis collections. The expansion of CD25+ CMV-T in short-term culture resulted in a mixed population of CD4+ and CD8+ T cells with CMV-specificity that secreted cytotoxic effector molecules and lysed CMVpp65 peptide-loaded phytohaemagglutinin-stimulated blasts. Furthermore CD25 expanded cells retained their suppressive capacity but did not maintain FoxP3 expression or secrete IL-10. In summary our data indicates that CD25 enrichment post CMV stimulation in G-CSF-mobilized PBMCs results in the simultaneous generation of both a functional population of anti-viral T cells and Tregs thus illustrating a potential single therapeutic strategy for the treatment of both GvHD and CMV reactivation following allogeneic haematopoietic stem cell transplantation. The use of G-CSF-mobilized cells as a starting material for cell therapy manufacture represents a feasible approach to alleviating the many problems incurred with successive donations and procurement of cells from unrelated donors. This approach may therefore simplify the clinical application of adoptive immunotherapy and broaden the approach for manufacturing multi-functional T cells.
Simulating Site-Specific Effects of a Changing Climate on Jack Pine Productivity Using a Modified Variant of the CROPLANNER Model  [PDF]
Peter F. Newton
Open Journal of Forestry (OJF) , 2012, DOI: 10.4236/ojf.2012.21004
Abstract: This study evaluated the site-specific effects of projected future climate conditions on the productivity of jack pine (Pinus banksiana Lamb.) plantations over the next 50 years (2011-2061). Climatic parameters as predicted by the Canadian Global Climate Model in association with a regional spatial climatic model, under 3 emissions scenarios (no change (NC), B1 and A2), were used as input values to a biophysical-based site-specific height-age model that was integrated into the CROPLANNER model and associated algorithm. Plantations managed under a basic silvicultural intensity on two site qualities at each of two geographically separated sites (northeastern and northwestern Ontario, Canada) were assessed. The results indicated that the stands situated on low-to-medium quality sites at both locations were largely unaffected by the predicted increase in temperature and precipitation rates. Conversely, however, stands situated on good-to-excellent quality sites grown under the B1 and A2 scenarios experienced consequential declines in stand development rates resulting in decreases in rotational mean sizes, biomass yields, recoverable end-product volumes, and economic worth. In addition to providing a plausible range of site-specific climate change outcomes on jack pine productivity within the central portion of the species range, these results suggest that future predictions that do not account for potential climate changes effects may overes- timate merchantable productivity on the higher site qualities by approximately 15%. As demonstrated, in- corporating biophysical-based site index functions within existing forest productivity models may repre- sent a feasible approach when accounting for climate change effects on yield outcomes of boreal species.
Genetic Worth Effect Models for Boreal Conifers and Their Utility When Integrated into Density Management Decision-Support Systems  [PDF]
Peter F. Newton
Open Journal of Forestry (OJF) , 2015, DOI: 10.4236/ojf.2015.51011
Abstract: Based on approaches deduced from previous research findings and empirical observations from density control experiments, genetic worth effect response models were developed for black spruce (Picea mariana (Mill) BSP.) and jack pine (Pinus banksiana Lamb.) plantations. The models accounted for the increased rate of stand development arising from the planting of genetically-improved stock through temporal adjustments to the species-specific site-based mean dominant height-age functions. The models utilized a relative height growth modifier based on known estimates of genetic gain. The models also incorporated a phenotypic juvenile age-mature age correlation function in order to account for the intrinsic temporal decline in the magnitude of genetic worth effects throughout the rotation. Integrating the functions into algorithmic variants of structural stand density management models produced stand development patterns that were consistent with axioms of even-aged stand dynamics.
Quantifying Growth Responses of Black Spruce and Jack Pine to Thinning within the Context of Density Management Decision-Support Systems  [PDF]
Peter F. Newton
Open Journal of Forestry (OJF) , 2015, DOI: 10.4236/ojf.2015.54035
Abstract: Models for quantifying the growth responses of black spruce (Picea mariana (Mill) BSP.) and jack pine (Pinus banksiana Lamb.) to precommercial thinning (PCT) treatments were developed. They accounted for the increased rate of stand development arising from PCT treatments through temporal adjustments to the species and site specific mean dominant height-age functions. Analytically, they utilized a relative height growth modifier consistent with observed density-dependent height repression effects. A phenotypic juvenile age-mature age correlation function was used to account for the intrinsic temporal decline in the magnitude of the PCT effect throughout the rotation. The resultant stand development patterns were in accord with theoretical and empirical expectations when the response models were integrated into algorithmic variants of structural stand density management models.
An assessment of the likely acceptability of vaginal microbicides for HIV prevention among women in rural Ghana
Martha A Abdulai, Frank Baiden, George Adjei, Samuel Afari-Asiedu, Kwame Adjei, Charlotte Tawiah, Sam Newton
BMC Women's Health , 2012, DOI: 10.1186/1472-6874-12-40
Abstract: The study employs a mixed method design, using cross-sectional survey and focus group discussions to further understand issues related to awareness and attitudes towards microbicide development, acceptability and perceived partner attitudes among pregnant women attending antenatal clinic in two health facilities in the Kintampo North municipality of Ghana. We used logistic regression to identify possible predictors of microbicide acceptability among the women surveyed.Although only 2% of the 504 women were aware of the development of microbicides, 95% were willing to use one when it became available. The cost of a microbicide that will be considered affordable to 50% of women was US$0.75. Although there were concerns about possible wetting effect, gel or creams were the most preferred (68% of women) formulation. Although 71% thought their partners will find microbicide acceptable, apprehensions about the feasibility of and consequences of failed discreet use were evident. 49% of women were concerned about possible negative effect of microbicide on sexual pleasure. Perceived partner acceptability (O.R. =17.7; 95%C.I. 5.03-62.5) and possibility of discreet use (O.R. =8.9 95%C.I. 2.63-30.13) were the important predictors of microbicide acceptability.Achieving microbicide acceptability among male partners should be made a part of the promotive interventions for ensuring effective use among women in rural Ghana.According to the 2010 UNAIDS report on the global AIDS epidemic, 33.3 million people live with HIV and 1.8 million deaths due to AIDS occurred in 2009. The total number of new infections in 2009 was 2.6 million. Sub-Saharan Africa remains the hardest hit by the HIV/AIDS pandemic and access to HIV prevention, treatment, care and support in this part of the world remains a major priority in global health [1,2].Heterosexual transmission accounts for more than 80% of all new HIV infections in sub-Saharan Africa [3]. Traditional HIV preventive methods such as condom us
Survival and haematological recovery of children with severe malaria transfused in accordance to WHO guidelines in Kilifi, Kenya
Samuel O Akech, Oliver Hassall, Allan Pamba, Richard Idro, Thomas N Williams, Charles RJC Newton, Kathryn Maitland
Malaria Journal , 2008, DOI: 10.1186/1475-2875-7-256
Abstract: A prospective observational study of survivors of severe and complicated malaria transfused in accordance with WHO guidelines. Children were invited for review at one month post-discharge. Non-attendees were traced in the community to ascertain survival.Outcome was assessed in 213 survivors. Those transfused were younger, had a higher base deficit, mean lactate levels and a higher prevalence of respiratory distress. As expected mean admission haemoglobin (Hb) was significantly lower amongst transfused [5.0 g/dL SD: 1.9] compared to non-transfused children [8.3 g/dL SD: 1.7] (p < 0.001). At discharge mean Hb was similar 6.4 g/dL [SD: 1.5] and 6.8 g/dL [SD: 1.6] respectively (p = 0.08), most children remained moderately to severely anaemic. At one month follow up 166 children (78%) returned, in whom we found no differences in mean Hb between the transfused (10.2 g/dL [SD: 1.7]) and non-transfused (10.0 g/dL [SD: 1.3]) survivors (p = 0.25). The major factors affecting haematological recovery were young age (<24 months) and concomitant malaria parasitaemia; Hb being 8.8 g/dL [SD: 1.5] in parasitaemic individuals compared with 10.5 g/dL [SD: 1.3] in those without (p < 0.001).This data supports the policy of rational use of blood transfusion, as proposed in the WHO guidelines, for children with anaemia in areas where access to emergency transfusion is not guaranteed. We have provided empirical data indicating that transfusion does not influence superior recovery in haemoglobin concentrations and therefore cannot be justified on this basis alone. This may help resolve the disparity between international policy and current clinical practice. Effective anti-malarial treatment at discharge may prevent reoccurrence of anaemia.Annually approximately two billion people are exposed to Plasmodium falciparum resulting in over 500 million clinical cases and about one million deaths predominantly in children less than five years living in the sub-Saharan Africa (SSA) [1]. Malaria com
Volume Expansion with Albumin Compared to Gelofusine in Children with Severe Malaria: Results of a Controlled Trial
Samuel Akech, Samson Gwer, Richard Idro, Greg Fegan, Alice C Eziefula, Charles R. J. C Newton, Michael Levin, Kathryn Maitland
PLOS ONE , 2006, DOI: 10.1371/journal.pctr.0010021
Abstract: Objectives Previous studies have shown that in children with severe malaria, resuscitation with albumin infusion results in a lower mortality than resuscitation with saline infusion. Whether the apparent benefit of albumin is due solely to its colloidal properties, and thus might also be achieved with other synthetic colloids, or due to the many other unique physiological properties of albumin is unknown. As albumin is costly and not readily available in Africa, examination of more affordable colloids is warranted. In order to inform the design of definitive phase III trials we compared volume expansion with Gelofusine (succinylated modified fluid gelatin 4% intravenous infusion) with albumin. Design This study was a phase II safety and efficacy study. Setting The study was conducted at Kilifi District Hospital, Kenya. Participants The participants were children admitted with severe falciparum malaria (impaired consciousness or deep breathing), metabolic acidosis (base deficit > 8 mmol/l), and clinical features of shock. Interventions The interventions were volume resuscitation with either 4.5% human albumin solution or Gelofusine. Outcome Measures Primary endpoints were the resolution of shock and acidosis; secondary endpoints were in-hospital mortality and adverse events including neurological sequelae. Results A total of 88 children were enrolled: 44 received Gelofusine and 44 received albumin. There was no significant difference in the resolution of shock or acidosis between the groups. Whilst no participant developed pulmonary oedema or fluid overload, fatal neurological events were more common in the group receiving gelatin-based intervention fluids. Mortality was lower in patients receiving albumin (1/44; 2.3%) than in those treated with Gelofusine (7/44; 16%) by intention to treat (Fisher's exact test, p = 0.06), or 1/40 (2.5%) and 4/40 (10%), respectively, for those treated per protocol (p = 0.36). Meta-analysis of published trials to provide a summary estimate of the effect of albumin on mortality showed a pooled relative risk of death with albumin administration of 0.19 (95% confidence interval 0.06–0.59; p = 0.004 compared to other fluid boluses). Conclusions In children with severe malaria, we have shown a consistent survival benefit of receiving albumin infusion compared to other resuscitation fluids, despite comparable effects on the resolution of acidosis and shock. The lack of similar mortality benefit from Gelofusine suggests that the mechanism may involve a specific neuroprotective effect of albumin, rather than solely the effect of
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