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Search Results: 1 - 10 of 151289 matches for " Jordan H. Stutz "
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Attonewton force detection using microspheres in a dual-beam optical trap in high vacuum
Gambhir Ranjit,David P. Atherton,Jordan H. Stutz,Mark Cunningham,Andrew A. Geraci
Physics , 2015, DOI: 10.1103/PhysRevA.91.051805
Abstract: We describe the implementation of laser-cooled silica microspheres as force sensors in a dual-beam optical dipole trap in high vacuum. Using this system we have demonstrated trap lifetimes exceeding several days, attonewton force detection capability, and wide tunability in trapping and cooling parameters. Measurements have been performed with charged and neutral beads to calibrate the sensitivity of the detector. This work establishes the suitability of dual beam optical dipole traps for precision force measurement in high vacuum with long averaging times, and enables future applications including the study of gravitational inverse square law violations at short range, Casimir forces, acceleration sensing, and quantum opto-mechanics.
Bioassay and Characterization of Several Palmer Amaranth (Amaranthus palmeri) Biotypes with Varying Tolerances to Glyphosate  [PDF]
Robert E. Hoagland, Robin H. Jordan, Neal D. Teaster
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.45127

The wide distribution of Palmer amaranth (Amaranthus palmeri) in the southern US became a serious weed control problem prior to the extensive use of glyphosate-resistant crops. Currently glyphosate-resistant populations of Palmer amaranth occur in many areas of this geographic region creating an even more serious threat to crop production. Investigations were undertaken using four biotypes (one glyphosate-sensitive, one resistant from Georgia and two of unknown tolerance from Mississippi) of Palmer amaranth to assess bioassay techniques for the rapid detection and level of resistance in populations of this weed. These plants were characterized with respect to chlorophyll, betalain, and protein levels and immunological responses to an antibody of 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) the target site of glyphosate. Only slight differences were found in four biotypes grown under greenhouse conditions regarding extractable soluble protein and chlorophyll content, but one biotype was found to be devoid of the red pigment, betalain. Measurement of early growth (seedling shoot elongation) of seedlings was a useful detection tool to determine glyphosate resistance. A leaf disc bioassay (using visual ratings and/or chlorophyll analysis) and an assay for shikimate accumulation were effective methods for determining herbicide resistance levels. The two unknown biotypes were found to be resistant to this herbicide. Some differences were found in the protein profiles of the biotypes, and western blots demonstrated a weak labeling of antibody in the glyphosate-sensitive biotype, whereas strong labeling occurred in the resistant plants. This latter point supports research by others, that increased copy number of the EPSPS gene (and increased EPSPS protein levels) is the resistance mechanism in this species. Results indicate the utility of certain bioassays for the determination of resistance and provide useful comparative information on the levels of inherent constituents among closely related plants.

Undulatory Locomotion
Netta Cohen,Jordan H. Boyle
Physics , 2009,
Abstract: Undulatory locomotion is a means of self-propulsion that relies on the generation and propagation of waves along a body. As a mode of locomotion it is primitive and relatively simple, yet can be remarkably robust. No wonder then, that it is so prevalent across a range of biological scales from motile bacteria to gigantic prehistoric snakes. Key to understanding undulatory locomotion is the body's interplay with the physical environment, which the swimmer or crawler will exploit to generate propulsion, and in some cases, even to generate the underlying undulations. This review focuses by and large on undulators in the low Reynolds numbers regime, where the physics of the environment can be much more tractable. We review some key concepts and theoretical advances, as well as simulation tools and results applied to selected examples of biological swimmers. In particular, we extend the discussion to some simple cases of locomotion in non-Newtonian media as well as to small animals, in which the nervous system, motor control, body properties and the environment must all be considered to understand how undulations are generated and modulated. To conclude, we review recent progress in microrobotic undulators that may one day become commonplace in applications ranging from toxic waste disposal to minimally invasive surgery.
ROSAT Observations of the Flare Star CC Eri
H. C. Pan,C. Jordan
Physics , 1994, DOI: 10.1093/mnras/272.1.11
Abstract: The flare/spotted spectroscopic binary star CC Eri was observed with the Position Sensitive Proportional Counter (PSPC) on the X-ray satellite ROSAT on 1990 July 9-11 and 1992 January 26-27. During the observations, the source was variable on time scales from a few minutes to several hours, with the X-ray (0.2-2 keV) luminosity in the range $\sim 2.5-6.8\times 10^{29} erg s^{-1}$. An X-ray flare-like event, which has a one hour characteristic rise time and a two hour decay time, was observed from CC Eri on 1990 July 10 16:14-21:34 (UT). The X-ray spectrum of the source can be described by current thermal plasma codes with two temperature components or with a continuous temperature distribution. The spectral results show that plasma at $Te\sim 10^{7}$ K exists in the corona of CC Eri. The variations in the observed source flux and spectra can be reproduced by a flare, adopting a magnetic reconnection model. Comparisons with an unheated model, late in the flare, suggest that the area and volume of the flare are substantially larger than in a solar two ribbon flare, while the electron pressure is similar. The emission measure and temperature of the non-flaring emission, interpreted as the average corona, lead to an electron pressure similar to that in a well-developed solar active region. Rotational modulation of a spot related active region requires an unphysically large X-ray flux in a concentrated area.
The three-front war: pursuing sustainability in a world shaped by explosive growth
John Stutz
Sustainability : Science, Practice and Policy , 2010,
Abstract: This article characterizes the pursuit of sustainability as a three-front war. Success requires reductions not only in the environmental impact per unit of economic activity, but also in the economic growth to which we have become accustomed and the inequality that has accompanied it. To explain the difficulty in responding to this threefold challenge, the article reviews historical data on the evolution of the global economy. In the subsequent discussion, I argue that the explosive growth experienced since 1950 has created a world in which rapid progress toward and beyond affluence is “business as usual.” The pursuit of sustainability is difficult in large part because it takes place within this world shaped by explosive growth. An income transition is suggested as part of the effort to win the three-front war.
Response to Creating the future we want by Alan D. Hecht, Joseph Fiksel, Scott C. Fulton, Terry F. Yosie, Neil C. Hawkins, Heinz Leuenberger, Jay Golden, & Thomas E. Lovejoy
John Stutz
Sustainability : Science, Practice and Policy , 2012,
Performative Forschung in der Kunstp dagogik am Beispiel von Szenen aus dem Seminar "Erforschen performativer Rituale im Stadtraum" Performative Research in Art Education: Scenes from the Seminar "Exploring Performative Rituals in City Space" Investigación performativa en la educación artística: escenas del seminario Análisis de los rituales performativos en el espacio de la ciudad
Ulrike Stutz
Forum : Qualitative Social Research , 2008,
Abstract: In meinem Beitrag fundiere ich einen performativen Ansatz kunstp dagogischer Forschung und wende diesen auf drei Beispiele aus einem Performance-Seminar mit Studierenden an. Hierbei unterziehe ich Video-Dokumentationen, die innerhalb von performativen Aktionen entstanden, einer inszenierenden Analyse mit medialen Verfahren. Mein Untersuchungsinteresse richtet sich dabei auf die Reaktionen von Passant/innen als expanded audience dieser Aktionen einer site specific art und somit auf die Ver nderungen der Qualit t des sozialen Raums, die durch die inszenierenden Interventionen stattfanden. Der Beitrag ist in der Verwendung von Texten, Videos und Animationen als multimediales Dokument aufbereitet. Durch die parallele Pr sentation unterschiedlicher Medienformate werden differenzsetzende und aktivierende Lesarten produziert. URN: urn:nbn:de:0114-fqs0802514 In my contribution, I lay the foundations for a performative approach to art education research and then apply it to three examples from a performance seminar conducted with university students. In the process, I subject video documentaries produced during performative exploration of everyday rituals in public space, to a fresh performative analysis using media techniques. My research interest targets the reactions of passers-by as an expanded audience, i.e., it targets the qualitative changes of social space brought about by these actions of site specific art. The contribution is presented as a multimedia document with videos and animations. The parallel presentation of different media formats produces differentiating and activating readings. URN: urn:nbn:de:0114-fqs0802514 En mi contribución, pongo los cimientos de un enfoque performativo para la investigación en la educación artística y lo aplico luego a tres ejemplos de un seminario de performance dirigido a estudiantes de la universidad. En el proceso, someto los videos de documentales producidos durante la exploración performativa de los rituales diarios en el espacio público a un análisis performativo fresco que usa medios técnicos. Mi interés de investigación se centra en las reacciones de transeúntes como una amplia audiencia, es decir, se centra en los cambios cualitativos del espacio social provocados por estas acciones del arte de lugar específico. La contribución es presentada como un documento multimedia con videos y animaciones. La presentación paralela con formatos de diferentes medios causa lecturas diferenciadoras y activadoras. URN: urn:nbn:de:0114-fqs0802514
Crying babies, tired mothers - challenges of the postnatal hospital stay: an interpretive phenomenological study
Elisabeth Kurth, Elisabeth Spichiger, Elisabeth Zemp Stutz, Johanna Biedermann, Irene H?sli, Holly P Kennedy
BMC Pregnancy and Childbirth , 2010, DOI: 10.1186/1471-2393-10-21
Abstract: Purposeful sampling was used to enroll 15 mothers of diverse parity and educational backgrounds, all of who had given birth to a full term healthy neonate. Using interpretive phenomenology, we analyzed interview and participant observation data collected during the postnatal hospital stay and at 6 and 12 weeks post birth. This paper reports on the postnatal hospital experience.Women's personal beliefs about beneficial childcare practices shaped how they cared for their newborn's and their own needs during the early postnatal period in the hospital. These beliefs ranged from an infant-centered approach focused on the infant's development of a basic sense of trust to an approach that balanced the infants' demands with the mother's personal needs. Getting adequate rest was particularly difficult for mothers striving to provide infant-centered care for an unsettled neonate. These mothers suffered from sleep deprivation and severe tiredness unless they were able to leave the baby with health professionals for several hours during the night.New mothers often need permission to attend to their own needs, as well as practical support with childcare to recover from birth especially when neonates are fussy. To strengthen family health from the earliest stage, postnatal care should establish conditions which enable new mothers to balance the care of their infant with their own needs.Comforting a crying baby while coping with personal tiredness can challenge mothers after birth. As many as 46%-87% of new mothers report problems with tiredness or fatigue [1,2], and disquieting infant crying is the most commonly reported reason parents consult health professionals [3]. Not surprising, the occurrence of postnatal tiredness is associated with the amount of infant crying [4,5]. In the worst case, infant crying and increasing exhaustion can cumulate into a vicious circle and negatively affect family health. Maternal exhaustion has been identified as a predictor of postpartum depressi
Vertical profiles of nitrous acid in the nocturnal urban atmosphere of Houston, TX
K. W. Wong, H.-J. Oh, B. L. Lefer, B. Rappenglück,J. Stutz
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2011,
Abstract: Nitrous acid (HONO) often plays an important role in tropospheric photochemistry as a major precursor of the hydroxyl radical (OH) in early morning hours and potentially during the day. However, the processes leading to formation of HONO and its vertical distribution at night, which can have a considerable impact on daytime ozone formation, are currently poorly characterized by observations and models. Long-path differential optical absorption spectroscopy (LP-DOAS) measurements of HONO during the 2006 TexAQS II Radical and Aerosol Measurement Project (TRAMP), near downtown Houston, TX, show nocturnal vertical profiles of HONO, with mixing ratios of up to 2.2 ppb near the surface and below 100 ppt aloft. Three nighttime periods of HONO, NO2 and O3 observations during TRAMP were used to perform model simulations of vertical mixing ratio profiles. By adjusting vertical mixing and NOx emissions the modeled NO2 and O3 mixing ratios showed very good agreement with the observations. Using a simple conversion of NO2 to HONO on the ground, direct HONO emissions, as well as HONO loss at the ground and on aerosol, the observed HONO profiles were reproduced by the model for 1–2 and 7–8 September in the nocturnal boundary layer (NBL). The unobserved increase of HONO to NO2 ratio (HONO/NO2) with altitude that was simulated by the initial model runs was found to be due to HONO uptake being too small on aerosol and too large on the ground. Refined model runs, with adjusted HONO uptake coefficients, showed much better agreement of HONO and HONO/NO2 for two typical nights, except during morning rush hour, when other HONO formation pathways are most likely active. One of the nights analyzed showed an increase of HONO mixing ratios together with decreasing NO2 mixing ratios that the model was unable to reproduce, most likely due to the impact of weak precipitation during this night. HONO formation and removal rates averaged over the lowest 300 m of the atmosphere showed that NO2 to HONO conversion on the ground was the dominant source of HONO, followed by traffic emission. Aerosol did not play an important role in HONO formation. Although ground deposition was also a major removal pathway of HONO, net HONO production at the ground was the main source of HONO in our model studies. Sensitivity studies showed that in the stable NBL, net HONO production at the ground tends to increase with faster vertical mixing and stronger NOx emission. Vertical transport was found to be the dominant source of HONO aloft.
Relationship between the column density distribution and evolutionary class of molecular clouds as viewed by ATLASGAL
J. Abreu-Vicente,J. Kainulainen,A. Stutz,T. Henning,H. Beuther
Physics , 2015, DOI: 10.1051/0004-6361/201424959
Abstract: We present the first study of the relationship between the column density distribution of molecular clouds within nearby Galactic spiral arms and their evolutionary status as measured from their stellar content. We analyze a sample of 195 molecular clouds located at distances below 5.5 kpc, identified from the ATLASGAL 870 micron data. We define three evolutionary classes within this sample: starless clumps, star-forming clouds with associated young stellar objects, and clouds associated with HII regions. We find that the N(H2) probability density functions (N-PDFs) of these three classes of objects are clearly different: the N-PDFs of starless clumps are narrowest and close to log-normal in shape, while star-forming clouds and HII regions exhibit a power-law shape over a wide range of column densities and log-normal-like components only at low column densities. We use the N-PDFs to estimate the evolutionary time-scales of the three classes of objects based on a simple analytic model from literature. Finally, we show that the integral of the N-PDFs, the dense gas mass fraction, depends on the total mass of the regions as measured by ATLASGAL: more massive clouds contain greater relative amounts of dense gas across all evolutionary classes.
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