1,737 research outputs found
Mass Rearing the Gypsy Moth Pupal Parasitoids \u3ci\u3eBrachymeria Lasus\u3c/i\u3e and \u3ci\u3eBrachymeria Intermedia\u3c/i\u3e (Hymenoptera: Chalcididae) for Small-Scale Laboratory Studies
An economical technique was developed for mass rearing the gypsy moth para- sitoids Brachymeria lasus and B. intermedia using a factitious host, the greater wax moth, Galleria mellonella (Lepidoptera: pyralidae). Percentages of host pupae producing adult B. lusus and B. intermedia were 72.2 and 67.5, respectively. Percentages of adult wax moths emerging from groups of pupae exposed to populations of B. lasus and B. intermedia were 3.4 and 9.8, respectively. Mean emergence times of males and females from parasitized pupae incubated at 29° C. were 12.1 days and 13.8 days for B. lasus and 11.9 days and 13.5 days for B. intermedia. This procedure provides a low-maintenance laboratory culture with high yields from host pupae
Float-polishing process and analysis of float-polished quartz
A fluid-mechanical model is developed for the float-polishing process. In this model laminar flow between the sample and the lap results in pressure gradients at the grooves that support the sample on a fluid layer. The laminar fluid motion also produces supersmooth, damage-free surfaces. Quartz substrates for applications in high-stress environments were float polished, and their surfaces were analyzed by optical scatterometry, photoacoustic spectroscopy, and atomic force microscopy. The removal of 100 µm of material by a lapping-polishing process, with final float polishing, left low levels of subsurface damage, with a surface roughness of approximately 0.2-nm rms
Delayed Decision-making in Real-time Beatbox Percussion Classification
This is an electronic version of an article published in Journal of New Music Research, 39(3), 203-213, 2010. doi:10.1080/09298215.2010.512979. Journal of New Music Research is available online at: www.tandfonline.com/openurl?genre=article&issn=1744-5027&volume=39&issue=3&spage=20
Lonely adatoms in space
There is a close relation between the problems of second layer nucleation in
epitaxial crystal growth and chemical surface reactions, such as hydrogen
recombination, on interstellar dust grains. In both cases standard rate
equation analysis has been found to fail because the process takes place in a
confined geometry. Using scaling arguments developed in the context of second
layer nucleation, I present a simple derivation of the hydrogen recombination
rate for small and large grains. I clarify the reasons for the failure of rate
equations for small grains, and point out a logarithmic correction to the
reaction rate when the reaction is limited by the desorption of hydrogen atoms
(the second order reaction regime)
Successful Flash-Cooling of Xenon Derivatized Myoglobin Crystals
This paper demonstrates for the first time a method for preparing cryocooled xenon-derivatized protein crystals. The method is based upon the hypothesis and subsequent observation that the diffusion of a xenon atom from a tight binding site following depressurization occurs on a timescale of minutes. We have observed significant changes in diffraction intensities from myoglobin crystals for up to 5 min following depressurization from 1 MPa of xenon. In accordance with this observation, a xenon-derivatized myoglobin crystal was cryocooled at ~95 K within 20 s of complete depressurization. A crystallographic data set was then collected to 2.0 Å resolution and isomorphous and anomalous difference Patterson maps revealed the presence of a well ordered xenon site with an occupancy of approximately 0.5. Phasing statistics for this site were of good quality and demonstrate the practicality of this method. The ability to cryocool xenon-derivatized crystals will make this heavy-atom substitution method even more useful for single-isomorphous-replacement and multiple-isomorphous-replacement phasing of macromolecules
NUISANCE: a neutrino cross-section generator tuning and comparison framework
NUISANCE is an open source C++ framework which facilitates detailed studies of neutrino interaction cross-section models implemented in Monte Carlo neutrino event generators. It provides a host of automated methods to perform comparisons of multiple generators to published cross-section measurements and each other. External reweighting libraries are used to allow the end-user to evaluate the impact of model parameters variations in the generators with data, or to tune the generator predictions to arbitrary dataset combinations. The design is modular and focusses on ease-of-use to allow new datasets and more generators to be added without requiring detailed understanding of the entire NUISANCE package. We discuss the motivation for the NUISANCE framework and suggested usage cases, alongside a description of its core structure
Double-Stranded RNA Attenuates the Barrier Function of Human Pulmonary Artery Endothelial Cells
Circulating RNA may result from excessive cell damage or acute viral infection and can interact with vascular endothelial cells. Despite the obvious clinical implications associated with the presence of circulating RNA, its pathological effects on endothelial cells and the governing molecular mechanisms are still not fully elucidated. We analyzed the effects of double stranded RNA on primary human pulmonary artery endothelial cells (hPAECs). The effect of natural and synthetic double-stranded RNA (dsRNA) on hPAECs was investigated using trans-endothelial electric resistance, molecule trafficking, calcium (Ca2+) homeostasis, gene expression and proliferation studies. Furthermore, the morphology and mechanical changes of the cells caused by synthetic dsRNA was followed by in-situ atomic force microscopy, by vascular-endothelial cadherin and F-actin staining. Our results indicated that exposure of hPAECs to synthetic dsRNA led to functional deficits. This was reflected by morphological and mechanical changes and an increase in the permeability of the endothelial monolayer. hPAECs treated with synthetic dsRNA accumulated in the G1 phase of the cell cycle. Additionally, the proliferation rate of the cells in the presence of synthetic dsRNA was significantly decreased. Furthermore, we found that natural and synthetic dsRNA modulated Ca2+ signaling in hPAECs by inhibiting the sarco-endoplasmic Ca2+-ATPase (SERCA) which is involved in the regulation of the intracellular Ca2+ homeostasis and thus cell growth. Even upon synthetic dsRNA stimulation silencing of SERCA3 preserved the endothelial monolayer integrity. Our data identify novel mechanisms by which dsRNA can disrupt endothelial barrier function and these may be relevant in inflammatory processes
Electron Paramagnetic Resonance Studies of Succinate:Ubiquinone Oxidoreductase from Paracoccus denitrificans
Electron paramagnetic resonance (EPR) studies of succinate:ubiquinone oxidoreductase (SQR) from Paracoccus denitrificans have been undertaken in the purified and membrane-bound states. Spectroscopic “signatures” accounting for the three iron-sulfur clusters (2Fe-2S, 3Fe-4S, and 4Fe-4S), cytochromeb, flavin, and protein-bound ubisemiquinone radicals have been obtained in air-oxidized, succinate-reduced, and dithionite-reduced preparations at 4–10 K. Spectra obtained at 170 K in the presence of excess succinate showed a signal typical of that of a flavin radical, but superimposed with another signal. The superimposed signal originated from two bound ubisemiquinones, as shown by spectral simulations. Power saturation measurements performed on the air-oxidized enzyme provided evidence for a weak magnetic dipolar interaction operating between the oxidized 3Fe-4S cluster and the oxidized cytochrome b. Power saturation experiments performed on the succinate- and dithionite-reduced forms of the enzyme demonstrated that the 4Fe-4S cluster is coupled weakly to both the 2Fe-2S and the 3Fe-4S clusters. Quantitative interpretation of these power saturation experiments has been achieved through redox calculations. They revealed that a spin-spin interaction between the reduced 3Fe-4S cluster and the cytochrome b (oxidized) may also exist. These findings form the first direct EPR evidence for a close proximity (≤2 nm) of the high potential 3Fe-4S cluster, situated in the succinate dehydrogenase part of the enzyme, and the low potential, low spin b-heme in the membrane anchor of the enzyme
The single morpheme -ed/-en of the English past/passive
All English regular verbs and about half its irregular verbs have the same form for the finite past tense and the past participle. The finite past tense is different from the participle only for a closed class of about 100 irregular verbs. These latter can be analyzed by a lexical device of wide-ranging applicability called Alternative Realization. All other Past forms of Vs, finite and non-finite, can then be derived from a single morpheme -ed which appears in two contexts: one when V is finite and one when it is selected by a semantically empty stative verb, have or be. There is also a third use of -ed to form passive participles, in both verbal and adjectival passives.The paper presents a formalized system of selection features for lexical items including but going beyond classical subcategorization. This system permits formulating a single full lexical entry for the suffix -ed that covers all its uses. The final version of this entry exemplifies how to specify Alternative Realization, uninterpretability of categories and disjunctive contexts, and independently justifies each of these notations
The effect of monomer evaporation on a simple model of submonolayer growth
We present a model for thin film growth by particle deposition that takes
into account the possible evaporation of the particles deposited on the
surface. Our model focuses on the formation of two-dimensional structures. We
find that the presence of evaporation can dramatically affect the growth
kinetics of the film, and can give rise to regimes characterized by different
``growth'' exponents and island size distributions. Our results are obtained by
extensive computer simulations as well as through a simple scaling approach and
the analysis of rate equations describing the system. We carefully discuss the
relationship of our model with previous studies by Venables and Stoyanov of the
same physical situation, and we show that our analysis is more general.Comment: 41 pages including figures, Revtex, to be published in Physical
Review
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