Effect of application of carcinogenic substances on the epidermal cell populations of mouse skin

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Multi-Factor Impact Analysis of Agricultural Production in Bangladesh with Climate Change

Diverse vulnerabilities of Bangladesh's agricultural sector in 16 sub-regions are assessed using experiments designed to investigate climate impact factors in isolation and in combination. Climate information from a suite of global climate models (GCMs) is used to drive models assessing the agricultural impact of changes in temperature, precipitation, carbon dioxide concentrations, river floods, and sea level rise for the 2040-2069 period in comparison to a historical baseline. Using the multi-factor impacts analysis framework developed in Yu et al. (2010), this study provides new sub-regional vulnerability analyses and quantifies key uncertainties in climate and production. Rice (aman, boro, and aus seasons) and wheat production are simulated in each sub-region using the biophysical Crop Environment REsource Synthesis (CERES) models. These simulations are then combined with the MIKE BASIN hydrologic model for river floods in the Ganges-Brahmaputra-Meghna (GBM) Basins, and the MIKE21Two-Dimensional Estuary Model to determine coastal inundation under conditions of higher mean sea level. The impacts of each factor depend on GCM configurations, emissions pathways, sub-regions, and particular seasons and crops. Temperature increases generally reduce production across all scenarios. Precipitation changes can have either a positive or a negative impact, with a high degree of uncertainty across GCMs. Carbon dioxide impacts on crop production are positive and depend on the emissions pathway. Increasing river flood areas reduce production in affected sub-regions. Precipitation uncertainties from different GCMs and emissions scenarios are reduced when integrated across the large GBM Basins' hydrology. Agriculture in Southern Bangladesh is severely affected by sea level rise even when cyclonic surges are not fully considered, with impacts increasing under the higher emissions scenario

Stops making sense: translational trade-offs and stop codon reassignment

Background Efficient gene expression involves a trade-off between (i) premature termination of protein synthesis; and (ii) readthrough, where the ribosome fails to dissociate at the terminal stop. Sense codons that are similar in sequence to stop codons are more susceptible to nonsense mutation, and are also likely to be more susceptible to transcriptional or translational errors causing premature termination. We therefore expect this trade-off to be influenced by the number of stop codons in the genetic code. Although genetic codes are highly constrained, stop codon number appears to be their most volatile feature. Results In the human genome, codons readily mutable to stops are underrepresented in coding sequences. We construct a simple mathematical model based on the relative likelihoods of premature termination and readthrough. When readthrough occurs, the resultant protein has a tail of amino acid residues incorrectly added to the C-terminus. Our results depend strongly on the number of stop codons in the genetic code. When the code has more stop codons, premature termination is relatively more likely, particularly for longer genes. When the code has fewer stop codons, the length of the tail added by readthrough will, on average, be longer, and thus more deleterious. Comparative analysis of taxa with a range of stop codon numbers suggests that genomes whose code includes more stop codons have shorter coding sequences. Conclusions We suggest that the differing trade-offs presented by alternative genetic codes may result in differences in genome structure. More speculatively, multiple stop codons may mitigate readthrough, counteracting the disadvantage of a higher rate of nonsense mutation. This could help explain the puzzling overrepresentation of stop codons in the canonical genetic code and most variants

Evaluation of the Vertical Method of Toothbrushing

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142229/1/jper0346.pd

The Miniature Sensor Technology Integration Program: An Overview

The Ballistic Missile Defense Organization Technology Deputate\u27s Miniature Sensor Technology Integration (MSTI) program was established to test in realistic operational scenarios, BMDO developed miniature sensors for missile detection and tracking on low cost, rapidly built and deployed low-earth orbit satellites. With the first MSTI mission launched less than a year after it was initiated, BMDO plans include launching 2-3 satellites per year throughout the five year defense plan. The near term direction of the MSTI program is to perform on-orbit functional demonstration of integrated sensor technologies that support theater missile launch detection and tracking. Embodying a build a little, test a little philosophy, the MSTI program builds upon the capabilities of both the spacecraft bus and the integrated payload suite for missile tracking, background clutter measurements, and ecological disaster monitoring from mission to mission. In addition to its primary mission, the MSTI program also serves as BMDO\u27s cornerstone both for exploring the potential for dual-use of DOD space-based sensors for environmental/ecological disaster monitoring and for executing joint, international space missions, such as with the Russians under proposals advanced within the Global Protection System political context. This paper will describe the MSTI program approach, results of the first mission and plans for the future

Stand density management implications on the woody quality of yellow birch (Betula alleghaniensis Britton) in the Sault Ste. Marie MNR District of Ontario

Creating quality tolerant hardwood stands through intensive silviculture and mapping their properties is considered a means for optimizing the value chain in Northeastern Ontario. A comprehensive literature review was conducted concerning the growth, morphology and factors influencing end merchantability of diffuse porous hardwoods, which commonly grow in Northeastern Canada and North America. It was seen that there was a gap in the literature concerning the effects varying degrees of density management have on the internal properties of the growing stock occurring on site. The literature did, however, provide a knowledge base from which to evolve. Based on the current gaps in the literature, mapping of the internal properties associated with density management of yellow birch was conducted from a research site 30 kilometers Northwest of Thessalon, Ontario in the Algoma Forest District. Density management associated with the specific research site reflect releasing trees to 10%, 20%, 30% and 40% of tree height at time of treatment, since the trees were on average 10m high the treatments consist of releasing plus trees to one, two, three and four m, respectively. Destructive testing was performed on 15 yellow birch (Betula alleghaniensis Britton) trees from the thinning trial located in the Northern regions of the Great Lakes St Lawrence forest zone. The results showed that the thinning treatments applied had a significant effect on the internal wood properties of the yellow birch growing on site. The greatest variability was not between treatments but axially throughout the trees. Janka Ball side hardness values attained from the test specimens were on average 24% higher than published values. Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) values attained were 15% and 15% lower than the published values, respectively. The average ring width values across all treatments analysed were found to be 80% higher than the published values. The values for the microscopic attributes (fibers and vessels) displayed no difference between treatments and followed published trends associated with morphological changes in the trees. It was observed that the properties do not follow any discernable pattern associated with the intensity of crop tree thinning intensity. It was determined that thinning treatments do have a significant effect on the internal mechanical properties of the yellow birch growing on site and is suggested that thinning can increase stem merchantability and decrease rotation ages

Quantum mechanics/molecular mechanics studies on the mechanism of action of cofactor pyridoxal 5'-phosphate in ornithine 4,5-aminomutase

A computational study was performed on the experimentally elusive cyclisation step in the cofactor pyridoxal 5′-phosphate (PLP)-dependent D-ornithine 4,5-aminomutase (OAM)-catalysed reaction. Calculations using both model systems and a combined quantum mechanics/molecular mechanics approach suggest that regulation of the cyclic radical intermediate is achieved through the synergy of the intrinsic catalytic power of cofactor PLP and the active site of the enzyme. The captodative effect of PLP is balanced by an enzyme active site that controls the deprotonation of both the pyridine nitrogen atom (N1) and the Schiff-base nitrogen atom (N2). Furthermore, electrostatic interactions between the terminal carboxylate and amino groups of the substrate and Arg297 and Glu81 impose substantial “strain” energy on the orientation of the cyclic intermediate to control its trajectory. In addition the “strain” energy, which appears to be sensitive to both the number of carbon atoms in the substrate/analogue and the position of the radical intermediates, may play a key role in controlling the transition of the enzyme from the closed to the open state. Our results provide new insights into several aspects of the radical mechanism in aminomutase catalysis and broaden our understanding of cofactor PLP-dependent reactions

Dendrodendritic synapses in the mouse olfactory bulb external plexiform layer

Odor information relayed by olfactory bulb projection neurons, mitral and tufted cells (M/T), is modulated by pairs of reciprocal dendrodendritic synaptic circuits in the external plexiform layer (EPL). Interneurons, which are accounted for largely by granule cells, receive depolarizing input from M/T dendrites and in turn inhibit current spread in M/T dendrites via hyperpolarizing reciprocal dendrodendritic synapses. Because the location of dendrodendritic synapses may significantly affect the cascade of odor information, we assessed synaptic properties and density within sublaminae of the EPL and along the length of M/T secondary dendrites. In electron micrographs the M/T to granule cell synapse appeared to predominate and was equivalent in both the outer and inner EPL. However, the dendrodendritic synapses from granule cell spines onto M/T dendrites were more prevalent in the outer EPL. In contrast, individual gephyrin-immunoreactive (IR) puncta, a postsynaptic scaffolding protein at inhibitory synapses used here as a proxy for the granule to M/T dendritic synapse was equally distributed throughout the EPL. Of significance to the organization of intrabulbar circuits, gephyrin-IR synapses are not uniformly distributed along M/T secondary dendrites. Synaptic density, expressed as a function of surface area, increases distal to the cell body. Furthermore, the distributions of gephyrin-IR puncta are heterogeneous and appear as clusters along the length of the M/T dendrites. Consistent with computational models, our data suggest that temporal coding in M/T cells is achieved by precisely located inhibitory input and that distance from the soma is compensated for by an increase in synaptic density.Fil: Bartel, Dianna L.. University Of Yale. School Of Medicine; Estados UnidosFil: Rela, Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Hsieh, Lawrence. University Of Yale. School Of Medicine; Estados UnidosFil: Greer, Charles A. . University Of Yale. School Of Medicine; Estados Unido

Embedded NiTi wires for improved dynamic thermomechanical performance of silicone elastomers

The extraordinary properties of shape memory NiTi alloy are combined with the inherent viscoelastic behavior of a silicon elastomer. NiTi wires are incorporated in a silicon elastomer matrix. Benefits include features as electrical/thermal conductivity, reinforcement along with enhanced damping performance and flexibility. To gain more insight of this composite, a comprehensive dynamic thermomechanical analysis is performed and the temperature- as well as frequency-dependent storage modulus and the mechanical loss factor are obtained. The analyses are realized for the composite and single components. Moreover, the models to express the examined properties and their temperature along with the frequency dependencies are also presented