1,606 research outputs found
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A perfect storm: An archaeological management crisis in the Mississippi River Delta
Engineered projects resulting in unintended consequences, coastal erosion, subsidence, and sea-level rise are rapidly destroying archaeological sites in the Mississippi River Delta (MRD). The processes of site obliteration are intensifying and accelerating due to anthropogenic transformation of the environment, including cumulative engineered alterations of the landscape and climate change. Combined with increased inundation and erosion from storm surges, hundreds of terrestrial sites formerly located on natural levees, barrier islands, and other coastal landforms are progressively eroded, redeposited, deeply buried, and submerged. These include thousand-year-old earthen mounds and shell middens constructed by Native Americans, as well as centuries-old fishing communities along the coast. These irreplaceable cultural properties can provide crucial information on the unique history and ecology of the MRD. Ongoing studies include consulting with interested parties and implementing data sharing agreements. Re- searchers have formed a consortium of universities and state and federal agencies, and are partnering with culturally affiliated Native American tribes, descendant groups, and coastal communities. The consortium is developing a robust GIS-enabled risk matrix for analyzing threats and effects to endangered sites. It is using the risk matrix to select 30 sites for monitoring, assessment, aerial photogrammetry, and recording environmental data on water table fluctuations. Analysis of action-based scientific data on these imperiled and rapidly disappearing places is urgently needed and will provide the impetus and baseline for future studies. Otherwise, ongoing site destruction will erase any remaining opportunities for learning about Louisiana’s deep history and diverse cultural heritage
New Perspective on Passively Quenched Single Photon Avalanche Diodes: Effect of Feedback on Impact Ionization
Single-photon avalanche diodes (SPADs) are primary devices in photon counting systems used in quantum cryptography, time resolved spectroscopy and photon counting optical communication. SPADs convert each photo-generated electron hole pair to a measurable current via an avalanche of impact ionizations. In this paper, a stochastically self-regulating avalanche model for passively quenched SPADs is presented. The model predicts, in qualitative agreement with experiments, three important phenomena that traditional models are unable to predict. These are: (1) an oscillatory behavior of the persistent avalanche current; (2) an exponential (memoryless) decay of the probability density function of the stochastic quenching time of the persistent avalanche current; and (3) a fast collapse of the avalanche current, under strong feedback conditions, preventing the development of a persistent avalanche current. The model specifically captures the effect of the load’s feedback on the stochastic avalanche multiplication, an effect believed to be key in breaking today’s counting rate barrier in the 1.55–μm detection window
Beef Reproductive Technology Adoption- Impact of Production Risk and Capitals
Agriculture, Beef, Artificial insemination, Estrus synchronization, Social capital, Production risk, Technology adoption, Farm Management,
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Ellipsoid Localisation Microscopy
Multilayered protein coats are crucial to the dormancy, robustness, and germination of bacterial spores. In Bacillus subtilis spores, the coat contains over 70 distinct proteins. Identifying which proteins reside in each layer may provide insight into their distinct functions. We present image analysis methods that determine the order and geometry of concentric protein layers by fitting a model description for a spheroidal fluorescent shell image to optical micrographs of spores incorporating fluorescent fusion proteins. The radius of a spherical protein shell can be determined with <10 nm error by fitting an equation to widefield fluorescence micrographs. Ellipsoidal shell axes can be fitted with comparable precision. The layer orders inferred for B. subtilis and B. megaterium are consistent with measurements in the literature. The aspect ratio of elongated spores and the tendency of some proteins to localize near their poles can be quantified, enabling measurement of structural anisotropy.We gratefully acknowledge support from MedImmune through the Beacon collaboration, the EPSRC Centre for Doctoral Training in Sensor Technologies and Applications (EP/L015889/1), and thank Clemens Kaminski, Romain Laine and Jose Casas-Finet for inspiring discussions.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.bpj.2015.09.02
Ellipsoid Localization Microscopy Infers the Size and Order of Protein Layers in Bacillus Spore Coats
Effect of dead space on avalanche speed
The effects of dead space (the minimum distance travelled by a carrier before acquiring enough energy to impact ionize) on the current impulse response and bandwidth of an avalanche multiplication process are obtained from a numerical model that maintains a constant carrier velocity but allows for a random distribution of impact ionization path lengths. The results show that the main mechanism responsible for the increase in response time with dead space is the increase in the number of carrier groups, which qualitatively describes the length of multiplication chains. When the dead space is negligible, the bandwidth follows the behavior predicted by Emmons but decreases as dead space increase
Clinical effectiveness and cost-effectiveness of open and arthroscopic rotator cuff repair [the UK Rotator Cuff Surgery (UKUFF) randomised trial]
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Scientific names of organisms : attribution, rights, and licensing
© The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in BMC Research Notes 7 (2014): 79, doi:10.1186/1756-0500-7-79.As biological disciplines extend into the ‘big data’ world, they will need a names-based infrastructure to index and interconnect distributed data. The infrastructure must have access to all names of all organisms if it is to manage all information. Those who compile lists of species hold different views as to the intellectual property rights that apply to the lists. This creates uncertainty that impedes the development of a much-needed infrastructure for sharing biological data in the digital world. The laws in the United States of America and European Union are consistent with the position that scientific names of organisms and their compilation in checklists, classifications or taxonomic revisions are not subject to copyright. Compilations of names, such as classifications or checklists, are not creative in the sense of copyright law. Many content providers desire credit for their efforts. A ‘blue list’ identifies elements of checklists, classifications and monographs to which intellectual property rights do not apply. To promote sharing, authors of taxonomic content, compilers, intermediaries, and aggregators should receive citable recognition for their contributions, with the greatest recognition being given to the originating authors. Mechanisms for achieving this are discussed
Knee joint neuromuscular activation performance during muscle damage and superimposed fatigue
This study examined the concurrent effects of exercise-induced muscle damage and superimposed acute fatigue on the neuromuscular activation performance of the knee flexors of nine males (age: 26.7 ± 6.1yrs; height 1.81 ± 0.05m; body mass 81.2 ± 11.7kg [mean ± SD]). Measures were obtained during three experimental conditions: (i) FAT-EEVID, involving acute fatiguing exercise performed on each assessment occasion plus a single episode of eccentric exercise performed on the first occasion and after the fatigue trial; (ii) FAT, involving the fatiguing exercise only and; (iii) CON consisting of no exercise. Assessments were performed prior to (pre) and at lh, 24h, 48h, 72h, and 168h relative to the eccentric exercise. Repeated-measures ANOVAs showed that muscle damage within the FAT-EEVID condition elicited reductions of up to 38%, 24%) and 65%> in volitional peak force, electromechanical delay and rate of force development compared to baseline and controls, respectively (F[io, 80] = 2.3 to 4.6; p to 30.7%>) following acute fatigue (Fp; i6] = 4.3 to 9.1; p ; Fp, iq = 3.9; p <0.05). The safeguarding of evoked muscle activation capability despite compromised volitional performance might reveal aspects of capabilities for emergency and protective responses during episodes of fatigue and antecedent muscle damaging exercise
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