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2010

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Articles 4231 - 4260 of 8620

Full-Text Articles in Physical Sciences and Mathematics

Genetic Variation In Past And Current Landscapes: Conservation Implications Based On Six Endemic Florida Scrub Plants, Eric S. Menges, Rebecca W. Dolan, Robert Pickert, Rebecca Yahr, Doria R. Gordon Mar 2010

Genetic Variation In Past And Current Landscapes: Conservation Implications Based On Six Endemic Florida Scrub Plants, Eric S. Menges, Rebecca W. Dolan, Robert Pickert, Rebecca Yahr, Doria R. Gordon

Rebecca W. Dolan

If genetic variation is often positively correlated with population sizes and the presence of nearby populations and suitable habitats, landscape proxies could inform conservation decisions without genetic analyses. For six Florida scrub endemic plants (Dicerandra frutescens, Eryngium cuneifolium, Hypericum cumulicola, Liatris ohlingerae, Nolina brittoniana, and Warea carteri), we relate two measures of genetic variation, expected heterozygosity and alleles per polymorphic locus (APL), to population size and landscape variables. Presettlement areas were estimated based on soil preferences and GIS soils maps. Four species showed no genetic patterns related to population or landscape factors. The other two species showed significant but inconsistent …


Publication Bias In Reports Of Animal Stroke Studies Leads To Major Overstatement Of Efficacy, Emily Sena, H. Bart Van Der Worp, Philip M.W. Bath, David W. Howells, Malcolm Macleod Mar 2010

Publication Bias In Reports Of Animal Stroke Studies Leads To Major Overstatement Of Efficacy, Emily Sena, H. Bart Van Der Worp, Philip M.W. Bath, David W. Howells, Malcolm Macleod

Validation of Animal Experimentation Collection

The consolidation of scientific knowledge proceeds through the interpretation and then distillation of data presented in research reports, first in review articles and then in textbooks and undergraduate courses, until truths become accepted as such both amongst “experts” and in the public understanding. Where data are collected but remain unpublished, they cannot contribute to this distillation of knowledge. If these unpublished data differ substantially from published work, conclusions may not reflect adequately the underlying biological effects being described. The existence and any impact of such “publication bias” in the laboratory sciences have not been described. Using the CAMARADES (Collaborative Approach …


Can Animal Models Of Disease Reliably Inform Human Studies?, H. Bart Van Der Worp, David W. Howells, Emily Sena, Michelle J. Porritt, Sarah Rewell, Victoria O'Collins, Malcolm Macleod Mar 2010

Can Animal Models Of Disease Reliably Inform Human Studies?, H. Bart Van Der Worp, David W. Howells, Emily Sena, Michelle J. Porritt, Sarah Rewell, Victoria O'Collins, Malcolm Macleod

Validation of Animal Experimentation Collection

  • The value of animal experiments for predicting the effectiveness of treatment strategies in clinical trials has remained controversial, mainly because of a recurrent failure of interventions apparently promising in animal models to translate to the clinic.
  • Translational failure may be explained in part by methodological flaws in animal studies, leading to systematic bias and thereby to inadequate data and incorrect conclusions about efficacy.
  • Failures also result because of critical disparities, usually disease specific, between the animal models and the clinical trials testing the treatment strategy.
  • Systematic review and meta-analysis of animal studies may aid in the selection of the most …


Incommensurability And Multi-Paradigm Grounding In Design Science Research: Implications For Creating Knowledge, Dirk S. Hovorka Mar 2010

Incommensurability And Multi-Paradigm Grounding In Design Science Research: Implications For Creating Knowledge, Dirk S. Hovorka

Dirk Hovorka

The ‘problem identification-design-build-evaluate-theorize’ structure of Design Science Research has been proposed as an approach to creating knowledge in information systems and in broader organizational and social domains. Although the approach has merit, the philosophical foundations of two specific components warrant attention. First, the grounding of design theory on potentially incommensurate kernel theories may produce incoherent design theory. In addition, the newly design theory has no strong logical connection to the kernel theories, and so cannot be used to test or validate the contributing kernel theories. Second, the philosophical grounding of evaluation may inadvertently shift from functionally-based measures of utility and …


Simple Examples Of Estimating Causal Effects Using Targeted Maximum Likelihood Estimation, Michael Rosenblum, Mark J. Van Der Laan Mar 2010

Simple Examples Of Estimating Causal Effects Using Targeted Maximum Likelihood Estimation, Michael Rosenblum, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

We present a brief overview of targeted maximum likelihood for estimating the causal effect of a single time point treatment and of a two time point treatment. We focus on simple examples demonstrating how to apply the methodology developed in (van der Laan and Rubin, 2006; Moore and van der Laan, 2007; van der Laan, 2010a,b). We include R code for the single time point case.


Lake Samish Water Monitoring Project 2010 Final Report, Robin A. Matthews, Joan Vandersypen Mar 2010

Lake Samish Water Monitoring Project 2010 Final Report, Robin A. Matthews, Joan Vandersypen

Lake Samish

This report describes work done as a continuation of the Lake Samish monitoring project started in June 2005. Additional data and lake information is available in the 2006–2008 final reports (Matthews, et al., 2006; Matthews and Vandersypen, 2007; Matthews and Vandersypen, 2008).

Lake Samish is a valuable aquatic resource, providing public access for boating, fishing, swimming, picnicking, and other water and lakeshore activities. Residents around the lake enjoy outstanding views of both the lake and its surrounding watershed, and the lake serves as a water supply for many of the lakeshore residents.

Lake Samish is located in the Washington State …


Guest-Free Monolayer Clathrate And Its Coexistence With Two-Dimensional High-Density Ice, Jaeil Bai, C. Austen Angell, Xiao Cheng Zeng Mar 2010

Guest-Free Monolayer Clathrate And Its Coexistence With Two-Dimensional High-Density Ice, Jaeil Bai, C. Austen Angell, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Three-dimensional (3D) gas clathrates are ice-like but distinguished from bulk ices by containing polyhedral nano-cages to accommodate small gas molecules. Without space filling by gas molecules, standalone 3D clathrates have not been observed to form in the laboratory, and they appear to be unstable except at negative pressure. Thus far, experimental evidence for guest‐free clathrates has only been found in germanium and silicon, although guest‐free hydrate clathrates have been found, in recent simulations, able to grow from cold stretched water, if first nucleated. Herein, we report simulation evidence of spontaneous formation of monolayer clathrate ice, with or without gas molecules, …


Limnological Assistance For Lake Mead National Recreation Area: Quarterly Report, Period Ending March 30, 2010, Margaret N. Rees Mar 2010

Limnological Assistance For Lake Mead National Recreation Area: Quarterly Report, Period Ending March 30, 2010, Margaret N. Rees

Limnological Studies

Project 1

• Technical assistance with the implementation of the Interagency Monitoring Action Plan (I-MAP) for Quagga Mussels is ongoing. Three sampling events took place this quarter and analysis of all samples (fall 2009 – spring 2010) is underway.

• Two graduate students are undergoing necessary training for the two small-scale research projects funded by this task agreement. Sampling is anticipated to begin in June 2010.

• The quarterly Interagency Quagga Mussel Meeting was held in March 2010.

Project 2

• Protocols relevant to the Long-term Limnological Aquatic Resource Monitoring and Research Plan (Plan) for Lakes Mead and Mohave have …


Improved Methods For Teaching Science, Stephanie Peterson, Sara Scott Mar 2010

Improved Methods For Teaching Science, Stephanie Peterson, Sara Scott

Browse All Undergraduate research

Utah State University’s Get Away Special (GAS) team will conduct research aboard NASA's microgravity research aircraft, the “vomit comet,” through the Reduced Gravity Student Flight Opportunities program. Team members come from mechanical and aerospace engineering, computer science, physics, science education, and business backgrounds. The team will spend ten days this summer at NASA’s Johnson Space Center and perform experiments on the aircraft to better understand nucleate boiling, a potential method of efficient heat transfer in space.


A Systemic Study Of Nucleate Boiling, Justin Koeln Mar 2010

A Systemic Study Of Nucleate Boiling, Justin Koeln

Posters

Nucleate boiling is a heavily researched form of heat transfer due to its associated high heat transfer rates. Applying two-phase heat transfer to space systems would allow these systems to become more capable, efficient, and compact. However, a fundamental understanding of boiling dynamics in the absence of buoyancy is yet to be developed. This study intends to analyze the effects of gravity, power input, and surface geometry during successive periods of microgravity provided by NASA’s “vomit comet” through the Reduced Gravity Student Flight Opportunities Program.


Funboe - Follow-Up Nucleate Boiling On-Flight Experiment: A Systematic Study Of Nucleate Boiling In Microgravity, Jt Farnsworth, Frank Mccown Mar 2010

Funboe - Follow-Up Nucleate Boiling On-Flight Experiment: A Systematic Study Of Nucleate Boiling In Microgravity, Jt Farnsworth, Frank Mccown

Posters

Utah State University’s Get Away Special (GAS) team was awarded the opportunity to participate in Reduced Gravity Student Flight Opportunities program administered by NASA. Six members of the GAS team will fly in a specialized jet which will simulate microgravity where the experiment can be performed in 30 second intervals. The purpose of the experiment is to determine the properties of nucleate boiling of water in weightlessness. The experiment will be monitored with temperature sensors, accelerometers, and high definition cameras and the results will be analyzed frame by frame. This will provide important information related to the dynamics of heat …


Follow Up Nucleate Boiling On-Flight Experiment, Andrew Fassmann Mar 2010

Follow Up Nucleate Boiling On-Flight Experiment, Andrew Fassmann

Presentations

No abstract provided.


Electrodeposited Silica Thin Films, Debbie Campbell-Rance Mar 2010

Electrodeposited Silica Thin Films, Debbie Campbell-Rance

Theses and Dissertations

Sol-gel derived silica thin film synthesis has gained prominence because of the mild processing conditions and widespread understanding of the chemistry of the process. Traditionally, silicate films are prepared by spin- and dip-coating but these materials lack the desired porosity for sensing, separations and catalysis applications. Electrochemical deposition was proposed to improve the porosity of silicate films. The main aims of this work were threefold. First we wanted to elucidate what parameters influenced film formation during electrodeposition. Then we wanted to understand how these parameters affected the morphology of the materials prepared. These films were characterized by profilometry, AFM, and …


An Analysis Of Nonignorable Nonresponse In A Survey With A Rotating Panel Design, Caterina Giusti, Roderick J. Little Mar 2010

An Analysis Of Nonignorable Nonresponse In A Survey With A Rotating Panel Design, Caterina Giusti, Roderick J. Little

The University of Michigan Department of Biostatistics Working Paper Series

Missing values to income questions are common in survey data. When the probabilities of nonresponse are assumed to depend on the observed information and not on the underlining unobserved amounts, the missing income values are missing at random (MAR), and methods such as sequential multiple imputation can be applied. However, the MAR assumption is often considered questionable in this context, since missingness of income is thought to be related to the value of income itself, after conditioning on available covariates. In this article we describe a sensitivity analysis based on a pattern-mixture model for deviations from MAR, in the context …


Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner Mar 2010

Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner

Mikhail Khenner

An introduction to mathematical modeling of ultrathin solid films and the role of such modeling in nanotechnologies: Educational/Research presentation for senior physics majors


New Experimental Limits On The Pauli-Forbidden Transitions In 12c Nuclei Obtained With 485 Days Borexino Data, G. Bellini, J. Benziger, S. Bonetti, M. Buizza Avanzini, B. Caccianiga, L. Cadonati, F. Calaprice, C. Carraro, A. Chavarria, F. Dalnoki-Veress, D. D'Angelo, S. Davini, H. De Kerret, A. Derbin, A. Etenko, K. Fomenko, D. Franco, C. Galbiati, S. Gazzana, C. Ghiano, M. Giammarchi, M. Goeger-Neff, A. Goretti, C. Grieb, E. Guardincerri, S. Hardy, Aldo Ianni, Andrea Ianni, M. Joyce, G. Korga, D. Kryn, M. Leung, T. Lewke, E. Litvinovich, B. Loer, P. Lombardi, L. Ludhova, I. Machulin, S. Manecki, W. Maneschg, G. Manuzio, Q. Meindl, E. Meroni, L. Miramonti, M. Misiaszek, D. Montanari, V. Muratova, L. Oberauer, M. Obolensky, F. Ortica, M. Pallavicini, L. Papp, L. Perasso, S. Perasso, Andrea Pocar, R. S. Raghavan, G. Ranucci, A. Razeto, A. Re, P. Risso, A. Romani, D. Rountree, A. Sabelnikov, R. Saldanha, C. Salvo, S. Schoenert, H. Simgen, M. Skorokhvatov, O. Smirnov, A. Sotnikov, S. Sukhotin, Y. Surorov, R. Tartaglia, G. Testera, D. Vignaud, R. B. Vogelaar, F. Von Feilitzsch, Y. Winter, M. Wojcik, M. Wurm, J. Xu, O. Zaimidoroga, S. Zavatarelli, G. Zuzel Mar 2010

New Experimental Limits On The Pauli-Forbidden Transitions In 12c Nuclei Obtained With 485 Days Borexino Data, G. Bellini, J. Benziger, S. Bonetti, M. Buizza Avanzini, B. Caccianiga, L. Cadonati, F. Calaprice, C. Carraro, A. Chavarria, F. Dalnoki-Veress, D. D'Angelo, S. Davini, H. De Kerret, A. Derbin, A. Etenko, K. Fomenko, D. Franco, C. Galbiati, S. Gazzana, C. Ghiano, M. Giammarchi, M. Goeger-Neff, A. Goretti, C. Grieb, E. Guardincerri, S. Hardy, Aldo Ianni, Andrea Ianni, M. Joyce, G. Korga, D. Kryn, M. Leung, T. Lewke, E. Litvinovich, B. Loer, P. Lombardi, L. Ludhova, I. Machulin, S. Manecki, W. Maneschg, G. Manuzio, Q. Meindl, E. Meroni, L. Miramonti, M. Misiaszek, D. Montanari, V. Muratova, L. Oberauer, M. Obolensky, F. Ortica, M. Pallavicini, L. Papp, L. Perasso, S. Perasso, Andrea Pocar, R. S. Raghavan, G. Ranucci, A. Razeto, A. Re, P. Risso, A. Romani, D. Rountree, A. Sabelnikov, R. Saldanha, C. Salvo, S. Schoenert, H. Simgen, M. Skorokhvatov, O. Smirnov, A. Sotnikov, S. Sukhotin, Y. Surorov, R. Tartaglia, G. Testera, D. Vignaud, R. B. Vogelaar, F. Von Feilitzsch, Y. Winter, M. Wojcik, M. Wurm, J. Xu, O. Zaimidoroga, S. Zavatarelli, G. Zuzel

Andrea Pocar

The Pauli exclusion principle (PEP) has been tested for nucleons (n,p) in 12C with the Borexino detector. The approach consists of a search for γ, n, p, and β± emitted in a non-Paulian transition of 1P3/2-shell nucleons to the filled 1S1/2 shell in nuclei. Due to the extremely low background and the large mass (278 tons) of the Borexino detector, the following most stringent up-to-date experimental bounds on PEP violating transitions of nucleons have been established: τ(12C→12C~+γ)⩾5.0×1031 yr, τ(12C→11B~+p)⩾8.9×1029 yr, τ(12C→11C~+n)⩾3.4×1030 yr, τ(12C→12N~+e-+νe~)⩾3.1×1030 yr, and τ(12C→12B~+e++νe)⩾2.1×1030 yr, all at 90% C.L. The corresponding upper limits on the relative strengths for …


A Grazing Incidence X-Ray Streak Camera For Ultrafast, Single-Shot Measurements, J. Feng, K. Engelhorn, B. I. Cho, H. J. Lee, M. Greaves, Christopher P. Weber, R. W. Falcone, H. A. Padmore, P. A. Heimann Mar 2010

A Grazing Incidence X-Ray Streak Camera For Ultrafast, Single-Shot Measurements, J. Feng, K. Engelhorn, B. I. Cho, H. J. Lee, M. Greaves, Christopher P. Weber, R. W. Falcone, H. A. Padmore, P. A. Heimann

Physics

An ultrafast x-ray streak camera has been realized using a grazing incidence reflection photocathode. X-rays are incident on a gold photocathode at a grazing angle of 20° and photoemitted electrons are focused by a large aperture magnetic solenoid lens. The streak camera has high quantum efficiency, 600 fs temporal resolution, and 6 mm imaging length in the spectral direction. Its single shot capability eliminates temporal smearing due to sweep jitter, and allows recording of the ultrafast dynamics of samples that undergo nonreversible changes.


Realistic Reconfiguration Of Crystalline (And Telecube) Robots, Greg Aloupis, Sébastien Collette, Mirela Damian, Erik D. Demaine, Dania El-Khechen, Robin Flatland, Stefan Langerman, Joseph O'Rourke, Val Pinciu, Suneeta Ramaswami, Vera Sacristán, Stefanie Wuhrer Mar 2010

Realistic Reconfiguration Of Crystalline (And Telecube) Robots, Greg Aloupis, Sébastien Collette, Mirela Damian, Erik D. Demaine, Dania El-Khechen, Robin Flatland, Stefan Langerman, Joseph O'Rourke, Val Pinciu, Suneeta Ramaswami, Vera Sacristán, Stefanie Wuhrer

Computer Science: Faculty Publications

In this paper we propose novel algorithms for reconfiguring modular robots that are composed of n atoms. Each atom has the shape of a unit cube and can expand/contract each face by half a unit, as well as attach to or detach from faces of neighboring atoms. For universal reconfiguration, atoms must be arranged in 2×2×2 modules. We respect certain physical constraints: each atom reaches at most unit velocity and (via expansion) can displace at most one other atom. We require that one of the atoms can store a map of the target configuration. Our algorithms involve a total of …


Equilibrium States Of A Test Particle Coupled To Finite-Size Heat Baths, Qun Wei, S. Taylor Smith, Roberto Onofrio Mar 2010

Equilibrium States Of A Test Particle Coupled To Finite-Size Heat Baths, Qun Wei, S. Taylor Smith, Roberto Onofrio

Dartmouth Scholarship

We report on numerical simulations of the dynamics of a test particle coupled to competing Boltzmann heat baths of finite size. After discussing some features of the single bath case, we show that the presence of two heat baths further constrains the conditions necessary for the test particle to thermalize with the heat baths. We find that thermalization is a spectral property in which the oscillators of the bath with frequencies in the range of the test particle characteristic frequency determine its degree of thermalization. We also find an unexpected frequency shift of the test particle response with respect to …


Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner Mar 2010

Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner

Mathematics Faculty Publications

An introduction to mathematical modeling of ultrathin solid films and the role of such modeling in nanotechnologies: Educational/Research presentation for senior physics majors


Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner Mar 2010

Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner

Mathematics Faculty Publications

An introduction to mathematical modeling of ultrathin solid films and the role of such modeling in nanotechnologies: Educational presentation for senior physics majors


Statistical Learning And Behrens-Fisher Distribution Methods For Heteroscedastic Data In Microarray Analysis, Nabin K. Manandhr-Shrestha Mar 2010

Statistical Learning And Behrens-Fisher Distribution Methods For Heteroscedastic Data In Microarray Analysis, Nabin K. Manandhr-Shrestha

USF Tampa Graduate Theses and Dissertations

The aim of the present study is to identify the di®erentially expressed genes be- tween two di®erent conditions and apply it in predicting the class of new samples using the microarray data. Microarray data analysis poses many challenges to the statis- ticians because of its high dimensionality and small sample size, dubbed as "small n large p problem". Microarray data has been extensively studied by many statisticians and geneticists. Generally, it is said to follow a normal distribution with equal vari- ances in two conditions, but it is not true in general. Since the number of replications is very small, …


Globular Structure Of A Human Immunodeficiency Virus-1 Protease (1difa Dimer) In An Effective Solvent Medium By A Monte Carlo Simulation, Ras B. Pandey, Barry L. Farmer Mar 2010

Globular Structure Of A Human Immunodeficiency Virus-1 Protease (1difa Dimer) In An Effective Solvent Medium By A Monte Carlo Simulation, Ras B. Pandey, Barry L. Farmer

Faculty Publications

A coarse-grained model is used to study the structure and dynamics of a human immunodeficiency virus-1 protease (1DIFA dimer) consisting of 198 residues in an effective solvent medium on a cubic lattice by Monte Carlo simulations for a range of interaction strengths. Energy and mobility profiles of residues are found to depend on the interaction strength and exhibit remarkable segmental symmetries in two monomers. Lowest energy residues such as Arg(41) and Arg(140) (most electrostatic and polar) are not the least mobile; despite the higher energy, the hydrophobic residues (Ile, Leu, and Val) are least mobile and form the core by …


Dsfs: Decentralized Security For Large Parallel File Systems, Zhongying Niu, Hong Jiang, Ke Zhou, Dan Feng, Tianming Yang, Dongliang Lei, Anli Chen Mar 2010

Dsfs: Decentralized Security For Large Parallel File Systems, Zhongying Niu, Hong Jiang, Ke Zhou, Dan Feng, Tianming Yang, Dongliang Lei, Anli Chen

CSE Technical Reports

This paper describes DSFS, a decentralized security system for large parallel file system. DSFS stores global access control lists (ACLs) in a centralized decisionmaking server and pushes pre-authorization lists (PALs) into storage devices. Thus DSFS allows users to flexibly set any access control policy for the global ACL or even change the global ACL system without having to upgrade the security code in their storage devices. With pre-authorization lists, DSFS enables a networkattached storage device to immediately authorize I/O, instead of demanding a client to acquire an authorization from a centralized authorization server at a crucial time. The client needs …


From Euler To Witten: A Short Survey Of The Volume Conjecture In Knot Theory, Uwe Kaiser Mar 2010

From Euler To Witten: A Short Survey Of The Volume Conjecture In Knot Theory, Uwe Kaiser

Uwe Kaiser

No abstract provided.


Topological Gravity On The Lattice, Simon Catterall Mar 2010

Topological Gravity On The Lattice, Simon Catterall

Physics - All Scholarship

In this paper we show that a particular twist of \cN=4 super Yang-Mills in three dimensions with gauge group SU(2) possesses a set of classical vacua corresponding to the space of flat connections of the {\it complexified} gauge group SL(2,C). The theory also contains a set of topological observables corresponding to Wilson loops wrapping non-trivial cycles of the base manifold. This moduli space and set of topological observables is shared with the Chern Simons formulation of three dimensional gravity and we hence conjecture that the Yang-Mills theory gives an equivalent description of the gravitational theory. Unlike the Chern Simons formulation …


A Low Threshold For North Atlantic Ice Rafting From “Low-Slung Slippery” Late Pliocene Ice Sheets, Ian Bailey, Clara T. Bolton, Robert M. Deconto, David Pollard, Ralf Schiebel, Paul A. Wilson Mar 2010

A Low Threshold For North Atlantic Ice Rafting From “Low-Slung Slippery” Late Pliocene Ice Sheets, Ian Bailey, Clara T. Bolton, Robert M. Deconto, David Pollard, Ralf Schiebel, Paul A. Wilson

Robert M DeConto

Suborbital variability in late Pleistocene records of ice-rafted debris and sea surface temperature in the North Atlantic Ocean appears most extreme during times of enlarged ice sheets with a well-constrained benthic oxygen isotope-defined “ice volume threshold” (δ18OT) for the “100 ka (inter)glacial” world. Information on climate instability for the earlier Pleistocene and late Pliocene is more fragmentary and/or of much lower temporal resolution, but the data available suggest similar behavior with δ18OT remaining more or less constant over the past 3000 ka. This finding is puzzling because it implies that ice rafting is highly sensitive to ice volume on short …


Four Kissing Circles, John Hawkins, David Stone Mar 2010

Four Kissing Circles, John Hawkins, David Stone

John B. Hawkins

No abstract provided.


A Balloon Sounding Technique For Measuring So2 Plumes, Gary A. Morris, Walter D. Komhyr, Jun Hirokawa, James Flynn, Barry Lefer, Nicholay Krotokov, Fong Ngan Mar 2010

A Balloon Sounding Technique For Measuring So2 Plumes, Gary A. Morris, Walter D. Komhyr, Jun Hirokawa, James Flynn, Barry Lefer, Nicholay Krotokov, Fong Ngan

Physics and Astronomy Faculty Publications

This paper reports on the development of a new technique for inexpensive measurements of SO2 profiles using a modified dual-ozonesonde instrument payload. The presence of SO2 interferes with the standard electrochemical cell (ECC) ozonesonde measurement, resulting in –1 molecule of O3 reported for each molecule of SO2 present (provided [O3].[SO2]). In laboratory tests, an SO2 filter made with CrO3 placed on the inlet side of the sonde removes nearly 100% of the SO2 present for concentrations up to 60 ppbv and remained effective after exposure to 2.8 3 1016 molecules of SO2 [equivalent to a column ;150 DU (1 DU …


Lorentz Violation With An Antisymmetric Tensor, Brett Altschul, Quentin G. Bailey, V. Alan Kostelecký Mar 2010

Lorentz Violation With An Antisymmetric Tensor, Brett Altschul, Quentin G. Bailey, V. Alan Kostelecký

Physics & Astronomy - Prescott

Field theories with spontaneous Lorentz violation involving an antisymmetric 2-tensor are studied. A general action including nonminimal gravitational couplings is constructed, and features of the Nambu- Goldstone and massive modes are discussed. Minimal models in Minkowski spacetime exhibit dualities with Lorentz-violating vector and scalar theories. The post-Newtonian expansion for nonminimal models in Riemann spacetime involves qualitatively new features, including the absence of an isotropic limit. Certain interactions producing stable Lorentz-violating theories in Minkowski spacetime solve the renormalization-group equations in the tadpole approximation.