5,449 research outputs found
Farmer Perspectives on Agroforestry Opportunities and Constraints in Cape Verde
In the Agua de Gato Watershed on the island of Santiago, Cape Verde Islands, 51 farmers were surveyed regarding their attitudes and knowledge of agroforestry. The farmers identified eight constraints to agroforestry implementation, with virtually all indicating that a source of loan funds was the major concern. Space or land constraints and availability of tree seedlings were identified as constraints by 94% and 88%, respectively. Despite these concerns, 92% of the farmers expressed a willingness to adopt or improve agroforestry practices in the watershed, with 73% expressing a willingness to establish fruit trees, 53% willing to establish trees or shrubs for fuelwood, and 16% willing to plant trees for shade
Corrosion of Civil War Era Sub Marine Explorer—Part 1
The Sub Marine Explorer is one of five submersibles (submarines) constructed prior to 1870 that have survived either in museums or as in situ archaeological sites around the world. Since 1869, the wreck of Explorer has emerged at low tide on the beach of Isla San Telmo, Archipiélago de las Perlas, Panama, located ~75 km southwest of Panama City in the Bay of Panama. In 2001, James Delgado visited the site. Locals described the wreck as a World War II-era Japanese midget submarine. Delgado consulted with Richard Wills, an expert on American Civil War submarines, and confirmed that the well-preserved wreck was the Sub Marine Explorer from the Civil War period
Corrosion of Civil War Era \u3ci\u3eSub Marine Explorer\u3c/i\u3e—Part 2
The Sub Marine Explorer was designed and built by Julius H. Kroehl, who was born in Prussia in 1820. After migrating to the United States in 1838 and becoming a citizen, he served in the Union Navy (United States Navy during the Civil War) as an underwater demolitions expert. He left the Navy in 1863 and began designing a “sub-marine” that would facilitate Union forces’ mine removal and obstruction clearance. At the end of the Civil War, he became an engineer for the Pacific Pearl Co., an organization interested in using the craft to recover pearls from deep sea oyster beds in the Bay of Panama. Decompression sickness (the bends), unknown at the time, began to affect the crew in 1869, which led to the abandonment of Explorer in the tidal zone of St. Elmo’s Island (Isla San Telmo) in the Archipielago de las Perlas, Panama
Corrosion of Civil War Era Sub Marine Explorer—Part 1
The Sub Marine Explorer is one of five submersibles (submarines) constructed prior to 1870 that have survived either in museums or as in situ archaeological sites around the world. Since 1869, the wreck of Explorer has emerged at low tide on the beach of Isla San Telmo, Archipiélago de las Perlas, Panama, located ~75 km southwest of Panama City in the Bay of Panama. In 2001, James Delgado visited the site. Locals described the wreck as a World War II-era Japanese midget submarine. Delgado consulted with Richard Wills, an expert on American Civil War submarines, and confirmed that the well-preserved wreck was the Sub Marine Explorer from the Civil War period
Convergence of Theory and Experiment on the Role of Preorganization, Quantum Tunneling, and Enzyme Motions into Flavoenzyme-Catalyzed Hydride Transfer
Hydride transfer is one of the most common reactions catalyzed by enzymatic systems, and it has become an object of study because of possible significant quantum tunneling effects. In the present work, we provide a combination of theoretical QM/MM simulations and experimental measurements of the rate constants and kinetic isotopic effects (KIEs) for the hydride transfer reaction catalyzed by morphinone reductase, MR. Quantum mechanical tunneling coefficients, computed in the framework of variational transition-state theory, play a significant role in this reaction, reaching values of 23.8 ± 5.5 for the lightest isotopologue—one of the largest values reported for enzymatic systems. This prediction is supported by the agreement between the theoretically predicted rate constants and the corresponding experimental values. Simulations indicate that the role of protein motions can be satisfactorily described as equilibrium fluctuations along the reaction coordinate, in line with a high degree of preorganization displayed by this enzyme.V.M. is grateful to the University of Bath for the award of a David Parkin Visiting Professorship. The authors thankfully acknowledge the computer resources, technical expertise and assistance provided by the “Centre de Calcul de la Universitat de València” through the use of Multivac and Tirant
Fumonisin B1 Toxicity in Grower-Finisher Pigs: A Comparative Analysis of Genetically Engineered Bt Corn and non-Bt Corn by Using Quantitative Dietary Exposure Assessment Modeling
In this study, we investigate the long-term exposure (20 weeks) to fumonisin B1 (FB1) in grower-finisher pigs by conducting a quantitative exposure assessment (QEA). Our analytical approach involved both deterministic and semi-stochastic modeling for dietary comparative analyses of FB1 exposures originating from genetically engineered Bacillus thuringiensis (Bt)-corn, conventional non-Bt corn and distiller’s dried grains with solubles (DDGS) derived from Bt and/or non-Bt corn. Results from both deterministic and semi-stochastic demonstrated a distinct difference of FB1 toxicity in feed between Bt corn and non-Bt corn. Semi-stochastic results predicted the lowest FB1 exposure for Bt grain with a mean of 1.5 mg FB1/kg diet and the highest FB1 exposure for a diet consisting of non-Bt grain and non-Bt DDGS with a mean of 7.87 mg FB1/kg diet; the chronic toxicological incipient level of concern is 1.0 mg of FB1/kg of diet. Deterministic results closely mirrored but tended to slightly under predict the mean result for the semi-stochastic analysis. This novel comparative QEA model reveals that diet scenarios where the source of grain is derived from Bt corn presents less potential to induce FB1 toxicity than diets containing non-Bt corn
Neuroinflammation in the normal-appearing white matter (NAWM) of the multiple sclerosis brain causes abnormalities at the nodes of Ranvier
Changes to the structure of nodes of Ranvier in the normal-appearing white matter (NAWM) of multiple sclerosis (MS) brains are associated with chronic inflammation. We show that the paranodal domains in MS NAWM are longer on average than control, with Kv1.2 channels dislocated into the paranode. These pathological features are reproduced in a model of chronic meningeal inflammation generated by the injection of lentiviral vectors for the lymphotoxin-α (LTα) and interferon-γ (IFNγ) genes. We show that tumour necrosis factor (TNF), IFNγ, and glutamate can provoke paranodal elongation in cerebellar slice cultures, which could be reversed by an N-methyl-D-aspartate (NMDA) receptor blocker. When these changes were inserted into a computational model to simulate axonal conduction, a rapid decrease in velocity was observed, reaching conduction failure in small diameter axons. We suggest that glial cells activated by pro-inflammatory cytokines can produce high levels of glutamate, which triggers paranodal pathology, contributing to axonal damage and conduction deficits
Experimental quantum tomography of photonic qudits via mutually unbiased basis
We present the experimental quantum tomography of 7- and 8-dimensional
quantum systems based on projective measurements in the mutually unbiased basis
(MUB-QT). One of the advantages of MUB-QT is that it requires projections from
a minimal number of bases to be performed. In our scheme, the higher
dimensional quantum systems are encoded using the propagation modes of single
photons, and we take advantage of the capabilities of amplitude- and
phase-modulation of programmable spatial light modulators to implement the
MUB-QT.Comment: Published versio
Synapse-associated protein 102/dlgh3 couples the NMDA receptor to specific plasticity pathways and learning strategies
Understanding the mechanisms whereby information encoded within patterns of action potentials is deciphered by neurons is central to cognitive psychology. The multiprotein complexes formed by NMDA receptors linked to synaptic membrane-associated guanylate kinase (MAGUK) proteins including synapse-associated protein 102 (SAP102) and other associated proteins are instrumental in these processes. Although humans with mutations in SAP102 show mental retardation, the physiological and biochemical mechanisms involved are unknown. Using SAP102 knock-out mice, we found specific impairments in synaptic plasticity induced by selective frequencies of stimulation that also required extracellular signal-regulated kinase signaling. This was paralleled by inflexibility and impairment in spatial learning. Improvement in spatial learning performance occurred with extra training despite continued use of a suboptimal search strategy, and, in a separate nonspatial task, the mutants again deployed a different strategy. Double-mutant analysis of postsynaptic density-95 and SAP102 mutants indicate overlapping and specific functions of the two MAGUKs. These in vivo data support the model that specific MAGUK proteins couple the NMDA receptor to distinct downstream signaling pathways. This provides a mechanism for discriminating patterns of synaptic activity that lead to long-lasting changes in synaptic strength as well as distinct aspects of cognition in the mammalian nervous system
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