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Search Results: 1 - 10 of 516775 matches for " W. A. Bryan "
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Structure, Hierarchy and Kin. An Ethnography of the Old Market in Puerto Princesa, Palawan, Philippines  [PDF]
Bryan W. Rich
Open Journal of Social Sciences (JSS) , 2017, DOI: 10.4236/jss.2017.56010
Abstract: Every day, thousands of customers patronize hundreds of vendors at the Old Market in Puerto Princesa, seeking the highest quality products at the most affordable price. It is a buyer’s market as the variety of available products is limited to mostly locally produced goods. Why does a customer patronize one vender rather than another? Do social relationships influence this decision? Or, is price king? Does the relationship between customer and employee affect the vendor’s success? This paper attempts to shed light on the kinship ties and social stratification between vendors, customers and employees and its effects, if any, on the market’s economic success. After more than 6 months of participant observations, my findings show that the fictive kinship ties which develop between the regular customer and vendor, and the social stratification between customer and employee provide a structured functionalism to support the overarching economic theme of the public market.
Femtosecond single- to few-electron point-projection microscopy for nanoscale dynamic imaging
A. R. Bainbridge,C. W. Barlow-Myers,W. A. Bryan
Physics , 2015,
Abstract: Femtosecond electron microscopy produces real-space images of matter on micrometre to nanometre length scales in a series of ultrafast snapshots, tracking the dynamic evolution of charge distributions. Given that femtosecond pulses of electrons self-disperse under space-charge broadening, the ideal operation mode (without active compression) is a single electron per pulse. Here, we demonstrate for the first time femtosecond single-electron point projection microscopy (fs-ePPM) in a laser-pump fs-e-probe configuration. The electron pulses in the present work have an energy of only 150 eV and take tens of picoseconds to propagate to the object under study. Nonetheless, we achieve a temporal resolution with a standard deviation of 120 fs, combined with a spatial resolution below a micrometre. We image the evolution of a localized region of charge at the apex of a nanoscale metal tip induced by 30 fs 800 nm laser pulses at 50 kHz. The rapidity of the strong-field response of the metal nanotip facilitates the characterization of the number of electrons per pulse. By comparing the spatial region of fastest experimental response to the outcome of charged particle modelling, we elucidate the electron pulse comprises on average one electron is not significantly influenced by space charge, rather geometric and kinematic broadening are the limiting factors. These observations demonstrate it is feasible to employ single-electron pulses for real-space imaging whilst maintaining femtosecond temporal resolutions. Dynamically imaging electric and magnetic fields and charge distributions on sub-micron length scales and sub-picosecond timescales opens up new avenues of ultrafast structural dynamics. Furthermore, through the use of active AC compression, such pulses are an ideal seed for few-femtosecond to attosecond imaging applications which will access sub-optical cycle processes in nanoplasmonics.
Observation of multiple ionization pathways for OCS in an intense laser field resolved by three-dimensional covariance mapping and visualized by hierarchical ionization topology
W. A. Bryan,W. R. Newell,J. H. Sanderson,A. J. Langley
Physics , 2006, DOI: 10.1103/PhysRevA.74.053409
Abstract: The two- and three-body Coulomb explosion of carbonyl sulfide (OCS) by 790 nm, 50 fs laser pulses focussed to $\approx $ 10$^{16}$ Wcm$^{-2}$ has been investigated by three-dimensional covariance mapping technique. For the first time in a triatomic molecule, a single charge state, in this case the trication, has been observed to dissociate into two distinct energy channels. With the aid of a three dimensional visualization technique to reveal the ionization hierarchy, evidence is presented for the existence of two sets of ionization pathways resulting from these two initial states. While one group of ions can be modeled using a Classical enhanced ionization model, the second group, consisting of mainly asymmetric channels, can not. The results provide clear evidence that an enhanced ionization approach must also be accompanied by an appreciation of the effects of excited ionic states and multi-electronic processes.
Estimating Summer Nutrient Concentrations in Northeastern Lakes from SPARROW Load Predictions and Modeled Lake Depth and Volume
W. Bryan Milstead, Jeffrey W. Hollister, Richard B. Moore, Henry A. Walker
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081457
Abstract: Global nutrient cycles have been altered by the use of fossil fuels and fertilizers resulting in increases in nutrient loads to aquatic systems. In the United States, excess nutrients have been repeatedly reported as the primary cause of lake water quality impairments. Setting nutrient criteria that are protective of a lakes ecological condition is one common solution; however, the data required to do this are not always easily available. A useful solution for this is to combine available field data (i.e., The United States Environmental Protection Agency (USEPA) National Lake Assessment (NLA)) with average annual nutrient load models (i.e., USGS SPARROW model) to estimate summer concentrations across a large number of lakes. In this paper we use this combined approach and compare the observed total nitrogen (TN) and total phosphorus (TN) concentrations in Northeastern lakes from the 2007 National Lake Assessment to those predicted by the Northeast SPARROW model. We successfully adjusted the SPARROW predictions to the NLA observations with the use of Vollenweider equations, simple input-output models that predict nutrient concentrations in lakes based on nutrient loads and hydraulic residence time. This allows us to better predict summer concentrations of TN and TP in Northeastern lakes and ponds. On average we improved our predicted concentrations of TN and TP with Vollenweider models by 18.7% for nitrogen and 19.0% for phosphorus. These improved predictions are being used in other studies to model ecosystem services (e.g., aesthetics) and dis-services (e.g. cyanobacterial blooms) for ~18,000 lakes in the Northeastern United States.
Hydraphiles: A Rigorously Studied Class of Synthetic Channel Compounds with In Vivo Activity
Saeedeh Negin,Bryan A. Smith,Alexandra Unger,W. Matthew Leevy,George W. Gokel
International Journal of Biomedical Imaging , 2013, DOI: 10.1155/2013/803579
Abstract: Hydraphiles are a class of synthetic ion channels that now have a twenty-year history of analysis and success. In early studies, these compounds were rigorously validated in a wide range of in vitro assays including liposomal ion flow detected by NMR or ion-selective electrodes, as well as biophysical experiments in planar bilayers. During the past decade, biological activity was observed for these compounds including toxicity to bacteria, yeast, and mammalian cells due to stress caused by the disruption of ion homeostasis. The channel mechanism was verified in cells using membrane polarity sensitive dyes, as well as patch clamping studies. This body of work has provided a solid foundation with which hydraphiles have recently demonstrated acute biological toxicity in the muscle tissue of living mice, as measured by whole animal fluorescence imaging and histological studies. Here we review the critical structure-activity relationships in the hydraphile family of compounds and the in vitro and in cellulo experiments that have validated their channel behavior. This report culminates with a description of recently reported efforts in which these molecules have demonstrated activity in living mice. 1. Introduction The outer membranes of organisms serve to enclose the functioning cell and separate it from the external environment [1]. This vital protective function is complicated by the need for the cell to permit the entry of nutrients and the egress of waste products. It is unclear what were the earliest barriers that permitted separate cells to evolve and ultimately to combine into higher life forms [2, 3]. Indeed, there is considerable scholarly effort currently underway in this area. What is clear is that along with the development of protective or confining membranes, structures and mechanisms had to evolve [4] that would permit selective passage of ions and molecules through them [5]. Today, the proteins that regulate ion balance and transmembrane transport are extremely complex molecules that interact directly with the membranes in which they are embedded, and they exhibit remarkable selectivity (specificity) in their chemical functions [6]. During the past two decades, considerable effort has been expended to develop synthetic amphiphiles that will insert into membranes and exhibit at least some of the functions of highly complex protein channels [7, 8]. There has been considerable success in this arena, and a number of reviews describe the efforts [9–13]. Our own effort in this area initially involved the compounds we have called “hydraphiles” [14].
Fatty acids increase neuronal hypertrophy of Pten knockdown neurons
Catherine J. Fricano,Paul W. Frazel,A. James O'Malley,Gary L. Westbrook,Bryan W. Luikart
Frontiers in Molecular Neuroscience , 2014, DOI: 10.3389/fnmol.2014.00030
Abstract: Phosphatase and tensin homolog (Pten) catalyzes the reverse reaction of PI3K by dephosphorylating PIP3 to PIP2. This negatively regulates downstream Akt/mTOR/S6 signaling resulting in decreased cellular growth and proliferation. Co-injection of a lentivirus knocking Pten down with a control lentivirus allows us to compare the effects of Pten knockdown between individual neurons within the same animal. We find that knockdown of Pten results in neuronal hypertrophy by 21 days post-injection. This neuronal hypertrophy is correlated with increased p-S6 and p-mTOR in individual neurons. We used this system to test whether an environmental factor that has been implicated in cellular hypertrophy could influence the severity of the Pten knockdown-induced hypertrophy. Implantation of mini-osmotic pumps delivering fatty acids results in increased neuronal hypertrophy and p-S6/p-mTOR staining. These hypertrophic effects were reversed in response to rapamycin treatment. However, we did not observe a similar increase in hypertrophy in response to dietary manipulations of fatty acids. Thus, we conclude that by driving growth signaling with fatty acids and knocking down a critical regulator of growth, Pten, we are able to observe an additive morphological phenotype of increased soma size mediated by the mTOR pathway.
Reconstruction of Atomic Ionization Probabilities in Intense Laser Fields
T. R. J. Goodworth,W. A. Bryan,I. D. Williams,W. R. Newell
Physics , 2005, DOI: 10.1088/0953-4075/38/17/001
Abstract: Application of a parallel-projection inversion technique to z-scan spectra of multiply charged xenon and krypton ions, obtained by non-resonant field ionization of neutral targets, has for the first time permitted the direct observation of intensity-dependent ionization probabilities. These ionization efficiency curves have highlighted the presence of structure in the tunnelling regime, previously unobserved under full-volume techniques.
Treatments for reversing warfarin anticoagulation in patients with acute intracranial hemorrhage: a structured literature review
Brett F Bechtel, Timothy C Nunez, Jennifer A Lyon, Bryan A Cotton, Tyler W Barrett
International Journal of Emergency Medicine , 2011, DOI: 10.1186/1865-1380-4-40
Abstract: A structured literature search and review of articles relevant to intracranial hemorrhage and warfarin and treatment in the emergency department was performed. Databases for PubMed, CINAHL, and Cochrane EBM Reviews were electronically searched using keywords covering the concepts of anticoagulation drugs, intracranial hemorrhage (ICH), and treatment. The results generated by the search were limited to English- language articles and reviewed for relevance to our topic. The multiple database searches revealed 586 papers for review for possible inclusion. The final consensus of our comprehensive search strategy was a total of 23 original studies for inclusion in our review.Warfarin not only increases the risk of but also the severity of ICH by causing hematoma expansion. Prothrombin complex concentrate is statistically significantly faster at correcting the INR compared to fresh frozen plasma transfusions. Recombinant factor VIIa appears to rapidly reverse warfarin's effect on INR; however, this treatment is not FDA-approved and is associated with a 5% thromboembolic event rate. Slow intravenous dosing of vitamin K is recommended in patients with ICH. The 30-day risk for ischemic stroke after discontinuation of warfarin therapy was 3-5%. The risks of not reversing the anticoagulation in ICH generally outweigh the risk of thrombosis in the acute setting.Increasing numbers of patients are on anticoagulation including warfarin. There is no uniform standard for reversing warfarin in intracranial hemorrhage. Intravenous vitamin K in addition to fresh frozen plasma or prothrombin complex concentrate is recommended be used to reverse warfarin-associated intracranial hemorrhage. No mortality benefit for one treatment regimen over another has been shown. Emergency physicians should know their hospital's available warfarin reversal options and be comfortable administering these treatments to critically ill patients.Outpatient prescriptions for warfarin increased 45% to 31 millio
The Effect of an Open Carpal Tunnel Release on Thumb CMC Biomechanics
Marc A. Tanner,Bryan P. Conrad,Paul C. Dell,Thomas W. Wright
Advances in Orthopedics , 2012, DOI: 10.1155/2012/151348
Abstract: Purpose. We have observed worsening thumb pain following carpal tunnel release (CTR) in some patients. Our purpose was to determine the effect of open CTR on thumb carpometacarpal (CMC) biomechanics. Methods. Five fresh-frozen cadaver arms with intact soft tissues were used. Each specimen was secured to a jig which fixed the forearm at 45° supination, and the wrist at 20° dorsiflexion, with thumb pointing up. The thumb was axially loaded with a force of 130 N. We measured 3D translation and rotation of the trapezium, radius, and first metacarpal, before and after open CTR. Motion between radius and first metacarpal, radius and trapezium, and first metacarpal and trapezium during loading was calculated using rigid body mechanics. Overall stiffness of each specimen was determined. Results. Total construct stiffness following CTR was reduced in all specimens but not significantly. No significant changes were found in adduction, pronation, or dorsiflexion of the trapezium with respect to radius after open CTR. Motion between radius and first metacarpal, between radius and trapezium, or between first metacarpal and trapezium after open CTR was not decreased significantly. Conclusion. From this data, we cannot determine if releasing the transverse carpal ligament alters kinematics of the CMC joint.
Emergence of Anthrax Edema Toxin as a Master Manipulator of Macrophage and B Cell Functions
Bryan T. Gnade,Scott T. Moen,Ashok K. Chopra,Johnny W. Peterson,Linsey A. Yeager
Toxins , 2010, DOI: 10.3390/toxins2071881
Abstract: Anthrax edema toxin (ET), a powerful adenylyl cyclase, is an important virulence factor of Bacillus anthracis. Until recently, only a modest amount of research was performed to understand the role this toxin plays in the organism’s immune evasion strategy. A new wave of studies have begun to elucidate the effects this toxin has on a variety of host cells. While efforts have been made to illuminate the effect ET has on cells of the adaptive immune system, such as T cells, the greatest focus has been on cells of the innate immune system, particularly the macrophage. Here we discuss the immunoevasive activities that ET exerts on macrophages, as well as new research on the effects of this toxin on B cells.
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