1,742 research outputs found
Origination of the Split Structure of Spliceosomal Genes from Random Genetic Sequences
The mechanism by which protein-coding portions of eukaryotic genes came to be separated by long non-coding stretches of DNA, and the purpose for this perplexing arrangement, have remained unresolved fundamental biological problems for three decades. We report here a plausible solution to this problem based on analysis of open reading frame (ORF) length constraints in the genomes of nine diverse species. If primordial nucleic acid sequences were random in sequence, functional proteins that are innately long would not be encoded due to the frequent occurrence of stop codons. The best possible way that a long protein-coding sequence could have been derived was by evolving a split-structure from the random DNA (or RNA) sequence. Results of the systematic analyses of nine complete genome sequences presented here suggests that perhaps the major underlying structural features of split-genes have evolved due to the indigenous occurrence of split protein-coding genes in primordial random nucleotide sequence. The results also suggest that intron-rich genes containing short exons may have been the original form of genes intrinsically occurring in random DNA, and that intron-poor genes containing long exons were perhaps derived from the original intron-rich genes
Gauge symmetry and W-algebra in higher derivative systems
The problem of gauge symmetry in higher derivative Lagrangian systems is
discussed from a Hamiltonian point of view. The number of independent gauge
parameters is shown to be in general {\it{less}} than the number of independent
primary first class constraints, thereby distinguishing it from conventional
first order systems. Different models have been considered as illustrative
examples. In particular we show a direct connection between the gauge symmetry
and the W-algebra for the rigid relativistic particle.Comment: 1+22 pages, 1 figure, LaTeX, v2; title changed, considerably expanded
version with new results, to appear in JHE
Geographic Coincidence of Increased Malaria Transmission Hazard and Vulnerability Occurring at the Periphery of two Tanzanian Villages.
The goal of malaria elimination necessitates an improved understanding of any fine-scale geographic variations in transmission risk so that complementary vector control tools can be integrated into current vector control programmes as supplementary measures that are spatially targeted to maximize impact upon residual transmission. This study examines the distribution of host-seeking malaria vectors at households within two villages in rural Tanzania. Host-seeking mosquitoes were sampled from 72 randomly selected households in two villages on a monthly basis throughout 2008 using CDC light-traps placed beside occupied nets. Spatial autocorrelation in the dataset was examined using the Moran's I statistic and the location of any clusters was identified using the Getis-Ord Gi* statistic. Statistical associations between the household characteristics and clusters of mosquitoes were assessed using a generalized linear model for each species. For both Anopheles gambiae sensu lato and Anopheles funestus, the density of host-seeking females was spatially autocorrelated, or clustered. For both species, houses with low densities were clustered in the semi-urban village centre while houses with high densities were clustered in the periphery of the villages. Clusters of houses with low or high densities of An. gambiae s.l. were influenced by the number of residents in nearby houses. The occurrence of high-density clusters of An. gambiae s.l. was associated with lower elevations while An. funestus was also associated with higher elevations. Distance from the village centre was also positively correlated with the number of household occupants and having houses constructed with open eaves. The results of the current study highlight that complementary vector control tools could be most effectively targeted to the periphery of villages where the households potentially have a higher hazard (mosquito densities) and vulnerability (open eaves and larger households) to malaria infection
Structural and cellular features in metaphyseal and diaphyseal periosteum of osteoporotic rats
Despite the important physiological role of periosteum in the pathogenesis and treatment of osteoporosis, little is known about the structural and cellular characteristics of periosteum in osteoporosis. To study the structural and cellular differences in both diaphyseal and metaphyseal periosteum of osteoporotic rats, samples from the right femur of osteoporotic and normal female Lewis rats were collected and tissue sections were stained with hematoxylin and eosin, antibodies or staining kit against tartrate resistant acid phosphatase (TRAP), alkaline phosphatase (ALP), vascular endothelial growth factor (VEGF), von Willebrand (vWF), tyrosine hydroxylase (TH) and calcitonin gene-related peptide (CGRP). The results showed that the osteoporotic rats had much thicker and more cellular cambial layer of metaphyseal periosteum compared with other periosteal areas and normal rats (PÂ <Â 0.001). The number of TRAP+ osteoclasts in bone resorption pits, VEGF+ cells and the degree of vascularization were found to be greater in the cambial layer of metaphyseal periosteum of osteoporotic rats (PÂ <Â 0.05), while no significant difference was detected in the number of ALP+ cells between the two groups. Sympathetic nerve fibers identified by TH staining were predominantly located in the cambial layer of metaphyseal periosteum of osteoporotic rats. No obvious difference in the expression of CGRP between the two groups was found. In conclusion, periosteum may play an important role in the cortical bone resorption in osteoporotic rats and this pathological process may be regulated by the sympathetic nervous system
A population-based surveillance study on severe acute maternal morbidity (near-miss) and adverse perinatal outcomes in Campinas, Brazil: The Vigimoma Project
BACKGROUND: Auditing of sentinel health events based on best-practice protocols has been recommended. This study describes a population-based investigation on adverse perinatal events including severe acute maternal morbidity (near-miss), maternal and perinatal mortality, as a health intervention to help improve the surveillance system. METHODS: From October to December 2005, all cases of maternal death (MD), near-miss (NM), fetal deaths (FD), and early neonatal deaths (END), occurring in Campinas, Brazil, were audited by maternal mortality committees. RESULTS: A total of 4,491 liveborn infants (LB) and 159 adverse perinatal events (35.4/1000 LB) were revised, consisting of 4 MD (89/100.000 LB) and 95 NM (21.1/1000 LB), 23.7 NM for each MD. In addition, 32 FD (7.1/1000 LB) and 28 END (6.2/1000 LB) occurred. The maternal death/near miss rate was 23.7:1. Some delay in care was recognized for 34%, and hypertensive complications comprised 57.8% of the NM events, followed by postpartum hemorrhage. CONCLUSION: Auditing near miss cases expanded the understanding of the spectrum from maternal morbidity to mortality and the importance of promoting adhesion to clinical protocols among maternal mortality committee members. Hypertensive disorders and postpartum hemorrhage were identified as priority topics for health providers training, and organization of care
The potential for sand dams to increase the adaptive capacity of East African drylands to climate change
Drylands are home to more than two billion people and are characterised by frequent, severe droughts. Such extreme events are expected to be exacerbated in the near future by climate change. A potentially simple and cost-effective mitigation measure against drought periods is sand dams. This little-known technology aims to promote subsoil rainwater storage to support dryland agro-ecosystems. To date, there is little long-term empirical analysis that tests the effectiveness of this approach during droughts. This study addresses this shortcoming by utilising multi-year satellite imagery to monitor the effect of droughts at sand dam locations. A time series of satellite images was analysed to compare vegetation at sand dam sites and control sites over selected periods of drought, using the normalised difference vegetation index. The results show that vegetation biomass was consistently and significantly higher at sand dam sites during periods of extended droughts. It is also shown that vegetation at sand dam sites recovers more quickly from drought. The observed findings corroborate modelling-based research which identified related impacts on ground water, land cover, and socio-economic indicators. Using past periods of drought as an analogue to future climate change conditions, this study indicates that sand dams have potential to increase adaptive capacity and resilience to climate change in drylands. It therefore can be concluded that sand dams enhance the resilience of marginal environments and increase the adaptive capacity of drylands. Sand dams can therefore be a promising adaptation response to the impacts of future climate change on drylands
AGREEMENT BETWEEN DIFFERENT PATHOLOGISTS IN HISTOPATHOLOGIC DIAGNOSIS OF 128 GASTRIC POLYPS
f(R) theories
Over the past decade, f(R) theories have been extensively studied as one of
the simplest modifications to General Relativity. In this article we review
various applications of f(R) theories to cosmology and gravity - such as
inflation, dark energy, local gravity constraints, cosmological perturbations,
and spherically symmetric solutions in weak and strong gravitational
backgrounds. We present a number of ways to distinguish those theories from
General Relativity observationally and experimentally. We also discuss the
extension to other modified gravity theories such as Brans-Dicke theory and
Gauss-Bonnet gravity, and address models that can satisfy both cosmological and
local gravity constraints.Comment: 156 pages, 14 figures, Invited review article in Living Reviews in
Relativity, Published version, Comments are welcom
Influence of homogenization conditions on physical properties and antioxidant activity of fully biodegradable pea protein-alpha-tocopherol films
In this study, antioxidant biodegradable films based
on pea protein and alpha-tocopherol were successfully developed
by solution casting. The effect of both the homogenization
conditions (rotor stator and microfluidizer) and the relative
humidity (RH) on the microstructure and physical properties
(transparency, tensile, oxygen and water vapour barrier
properties) of pea protein/alpha-tocopherol-based films was
evaluated. The addition of alpha-tocopherol produced minimal
changes in the films transparency, while providing them
with antioxidant properties and improved water vapour and
oxygen barrier properties (up to 30 % in both water vapour
and oxygen permeability) when films were at low and intermediate
RH. The addition of alpha-tocopherol in
microfluidized films gave rise to an increase in their resistance
to break and extensibility (up to 27 % in E values) at intermediate
and high RH. These results add a new insight into the
potential of employing pea protein and alpha-tocopherol in the
development of fully biodegradable antioxidant films which
are of interest in food packagingThe authors acknowledge the financial support from the Spanish Ministerio de Educacion y Ciencia throughout the project AGL2010-20694, co-funded by FEDER. Author M.J.Fabra is a recipient of a Juan de la Cierva contract from the Spanish Ministerio de Economia y Competitividad.Fabra, MJ.; JimĂ©nez, A.; Talens Oliag, P.; Chiralt, A. (2014). Influence of homogenization conditions on physical properties and antioxidant activity of fully biodegradable pea protein-alpha-tocopherol films. Food and Bioprocess Technology. 7(12):3569-3578. https://doi.org/10.1007/s11947-014-1372-0S35693578712ASTM (1995). Standard test methods for water vapor transmission of materials. Standards Desingnations: E96-95. In: Annual Book of ASTM Standards (pp. 406-413); American Society for Testing and Materials: Philadelphia, PA.ASTM (2001). Standard test method for tensile properties of thin plastic sheeting. Standard D882. In: Annual book of American Standard Testing Methods (pp 162-170). D882. Philadelphia:ASTM.Bertan, L. C., Tanada-Palmu, P. S., Siani, A. C., & Grosso, C. R. F. (2005). Effect of fatty acids and âBrazilian elemiâ on composite films based on gelatin. Food Hydrocolloids, 19(1), 73â82.Byun, Y., Kim, Y. T., & Whiteside, S. (2010). Characterization of an antioxidant polylactic acid (PLA) film prepared with alpha-tocopherol, BHT and polyethylene glycol using film cast extruder. Journal of Food Engineering, 100, 239â244.Cerqueira, M. A., Costa, M. J., Fuciños, C., Pastrana, L. M., & Vicente, A. A. (2014). Development of active and nanotechnology-based smart edible packaging systems: physical-chemical characterization. Food and Bioprocess Technology, 7(5), 1472â1482.Choi, W. S., & Han, J. H. (2001). Physical and mechanical properties of peaâprotein-based edible films. Journal of Food Science, 66, 319â322.Choi, W. S., & Han, J. H. (2002). Film-forming mechanism and heat denaturation effects on the physical and chemical properties of pea-protein-isolate edible films. Journal of Food Science, 67, 1399â1406.Fabra, M. J., Talens, P., & Chiralt, A. (2009). Microstructure and optical properties of sodium caseinate films containing oleic acidebeeswax mixtures. Food Hydrocolloids, 23, 676â683.Fabra, M. J., Talens, P., & Chiralt, A. (2010). Water sorption isotherms and phase transitions of sodium caseinateâlipid films as affected by lipid interactions. Food Hydrocolloids, 24, 384â391.Fabra, M. J., Hambleton, A., Talens, P., Debeaufort, F., & Chiralt, A. (2011). Effect of ferulic acid and α-tocopherol antioxidants on properties of sodium caseinate edible films. Food Hydrocolloids, 25, 1441â1447.Fabra, M. J., Talens, P., Gavara, R., & Chiralt, A. (2012). Barrier properties of sodium caseinate films as affected by lipid composition and moisture content. Journal of Food Engineering, 109, 372â379.Frankel, E. N., Huang, S. W., Kanner, J., & German, J. B. (1994). Interfacial phenomena in the evaluation of antioxidants: bulk oils vs emulsions. Journal of Agriculture and Food Chemistry, 42(5), 1054â1059.GĂłmez-Estaca, J., GimĂ©nez, B., Montero, P., & GĂłmez-GuillĂ©n, M. C. (2009). Incorporation of antioxidant borage extract into edible films based on sole skin gelatin or a commercial fish gelatin. Journal of Food Engineering, 92, 78â85.Huang, S. W., Frankel, E. N., & German, J. B. (1994). Antioxidant activity of alpha.- and.gamma.-tocopherols in bulk oils and in oil-in-water emulsions. Journal of Agriculture and Food Chemistry, 42(10), 2108â2114.Hutchings, J. B. (1999). Food and colour appearance (2nd ed.). Gaithersburg: Chapman and Hall Food Science Book, Aspen Publication.JimĂ©nez, A., Fabra, M. J., Talens, P., & Chiralt, A. (2010). Effect of lipid self-association on the microstructure and physical properties of hydroxypropylmethylcellulose edible films containing fatty acids. Carbohydrate Polymers, 82(3), 585â593.JimĂ©nez, A., Fabra, M. J., Talens, P., & Chiralt, A. (2013). Physical properties and antioxidant capacity of starch-sodium caseinate films containing lipids. Journal of Food Engineering, 116(3), 695â702.Jung, M. Y., & Min, D. B. (1990). Effects of alpha-. Îł-, and ÎŽ-tocopherols on oxidative stability of soybean oil. Journal of Food Science, 55(5), 1464â1465.LĂłpez-de-Dicastillo, C., Alonso, J. M., CatalĂĄ, R., Gavara, R., & HernĂĄndez-Muñoz, P. (2010). Improving the antioxidant protection of packaged food by incorporating natural flavonoids into ethylene-vinyl alcohol copolymer (EVOH) films. Journal of Agricultural and Food Chemistry, 58, 10958â10964.Ma, W., Tang, C.-H., Yin, S.-W., Yang, X. Q., Qi, J. R., & Xia, N. (2012). Effect of homogenization conditions on properties of gelatin-olive oil composite films. Journal of Food Engineering, 113(1), 136â142.Mauer, L. J., Smith, D. E., & Labuza, T. P. (2000). Water vapor permeability, mechanical, and structural properties of edible ÎČ-casein films. International Dairy Journal, 10(5â6), 353â358.Mc Hugh, T. H., Avena-Bustillos, R., & Krochta, J. M. (1993). Hydrophobic edible films:modified procedure for water vapor permeability and explanation of thickness effects. Journal of Food Science, 58(4), 899â903.McHugh, T. H., & Krochta, J. M. (1994). Dispersed phase particle size effects on water vapour permeability of whey proteinâbeeswax emulsion films. Journal of Food Processing and Preservation, 18, 173â188.Ozkan, G., Simsek, B., & Kuleasan, H. (2007). Antioxidant activities of Satureja cilicica essential oil in butter and in vitro. Journal of Food Engineering, 79, 1391â1396.Pereira de Abreu, D. A., Paseiro Losada, P., Maroto, J., & Cruz, J. M. (2011). Natural antioxidant active packaging film and its effect on lipid damage in frozen blue shark (Prionace glauca). Innovative Food Science and Emerging Technologies, 12, 50â55.Re, R., Pellegrini, N., Proteggente, A., Pannala, A., Yang, M., & Rice-Evans, C. (1999). Antioxidant activity applying an improved ABTS radical cation decoloration assay. Free Radical Biology and Medicine, 26, 1231â1237.Roos, Y. H. (1995). Phase transitions in food. San Diego: Academic Press.Salgado, P. R., Molina Ortiz, S. E., Petruccelli, S., & Mauri, A. N. (2010). Biodegradable sunflower protein films naturally activated with antioxidant compounds. Food Hydrocolloids, 24(5), 525â533.Salgado, P. R., FernĂĄndez, G. B., Drago, S. R., & Mauri, A. N. (2011). Addition of bovine plasma hydrolysates improves the antioxidant properties of soybean and sunflower protein-based films. Food Hydrocolloids, 25, 1433â1440.Samaranayaka, A. G. P., & Li-Chan, E. C. Y. (2008). Autolysis-assisted production of fish protein hydrolysates with antioxidant properties form Pacific hake (Merluccius productus). Food Chemistry, 107, 768â776.Souza, B. W. S., Cerqueira, A., Casariego, A., Lima, A. M. P., Teixeira, J. A., & Vicente, A. A. (2009). Effect of moderate electric fields in the permeation properties of chitosan coatings. Food Hydrocolloids, 23, 2110â2115
Maternal risk factors for abnormal placental growth: The national collaborative perinatal project
<p>Abstract</p> <p>Background</p> <p>Previous studies of maternal risk factors for abnormal placental growth have focused on placental weight and placental ratio as measures of placental growth. We sought to identify maternal risk factors for placental weight and two neglected dimensions of placental growth: placental thickness and chorionic plate area.</p> <p>Methods</p> <p>We conducted an analysis of 24,135 mother-placenta pairs enrolled in the National Collaborative Perinatal Project, a prospective cohort study of pregnancy and child health. We defined growth restriction as < 10<sup>th </sup>percentile and hypertrophy as > 90<sup>th </sup>percentile for three placental growth dimensions: placental weight, placental thickness and chorionic plate area. We constructed parallel multinomial logistic regression analyses to identify (a) predictors of restricted growth (vs. normal) and (b) predictors of hypertrophic growth (vs. normal).</p> <p>Results</p> <p>Black race was associated with an increased likelihood of growth restriction for placental weight, thickness and chorionic plate area, but was associated with a reduced likelihood of hypertrophy for these three placental growth dimensions. We observed an increased likelihood of growth restriction for placental weight and chorionic plate area among mothers with hypertensive disease at 24 weeks or beyond. Anemia was associated with a reduced likelihood of growth restriction for placental weight and chorionic plate area. Pre-pregnancy BMI and pregnancy weight gain were associated with a reduced likelihood of growth restriction and an increased likelihood of hypertrophy for all three dimensions of placental growth.</p> <p>Conclusion</p> <p>Maternal risk factors are either associated with placental growth restriction or placental hypertrophy not both. Our findings suggest that the placenta may have compensatory responses to certain maternal risk factors suggesting different underlying biological mechanisms.</p
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