1,629 research outputs found
Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the Sgr A complex
We observed OH, HO, HN, CO, and C towards the +50 km/s
cloud (M-0.02-0.07), the CND and the +20 km/s (M-0.13-0.08) cloud in the Sgr A
complex with the VLA, Odin and SEST. Strong OH absorption, HO emission and
absorption lines were seen at all three positions. Strong CO emissions
were seen towards the +50 and +20 km/s clouds. The CND is rich in HO and
OH, and these abundances are considerably higher than in the surrounding
clouds, indicating that shocks, star formation and clump collisions prevail in
those objects. A comparison with the literature reveals that it is likely that
PDR chemistry including grain surface reactions, and perhaps also the
influences of shocks has led to the observed abundances of the observed
molecular species studied here. In the redward high-velocity line wings of both
the +50 and +20 km/s clouds and the CND, the very high HO abundances are
suggested to be caused by the combined action of shock desorption from icy
grain mantles and high-temperature, gas-phase shock chemistry. Only three of
the molecules are briefly discussed here. For OH and HO three of the nine
observed positions are shown, while a map of the CO emission is
provided. An extensive paper was recently published with Open Access (Karlsson
et al. 2013; http://www.aanda.org/articles/aa/pdf/2013/06/aa20471-12.pdf ).Comment: Proc. of a Conf. on IAU Symposium No.303: The Galactic Center:
Feeding and Feedback in a Normal Galactic Nucleus 2013, Santa Fe, NM (USA
Odin observations of ammonia in the Sgr A +50 km/s Cloud and Circumnuclear Disk
Context. The Odin satellite is now into its sixteenth year of operation, much
surpassing its design life of two years. One of the sources which Odin has
observed in great detail is the Sgr A Complex in the centre of the Milky Way.
Aims. To study the presence of NH3 in the Galactic Centre and spiral arms.
Methods. Recently, Odin has made complementary observations of the 572 GHz NH3
line towards the Sgr A +50 km/s Cloud and Circumnuclear Disk (CND). Results.
Significant NH3 emission has been observed in both the +50 km/s Cloud and the
CND. Clear NH3 absorption has also been detected in many of the spiral arm
features along the line of sight from the Sun to the core of our Galaxy.
Conclusions. The very large velocity width (80 km/s) of the NH3 emission
associated with the shock region in the southwestern part of the CND may
suggest a formation/desorption scenario similar to that of gas-phase H2O in
shocks/outflows.Comment: 5 pages, 3 figures, 3 table
Structure and kinematics of the molecular spiral arms in M51
Mapping of the CO(1-0) emission from the spiral galaxy was made with the Onsala 20 m antenna. The observations show that the emission is considerably enhanced in spiral arms which appear to originate as intense ridges of emission about 1 kpc from the nucleus. One of the main objectives for the 1986 observations was to study the variations of the tangential velocity component of molecular gas across a spiral arm. The radial velocity was found to have a velocity shift similar to that predicted by the density wave theory. The present (1986) observations of the inner southern spiral arm of M51 show that the tangential velocity component also behaves in a way which conforms with the density wave model. The molecular arms were compared with the H alpha ionized gas arms of Tully (1974) and it was found that the ionized gas appears to have its maximum intensity slightly outside the molecular arm
Statistical Analysis When the Data is an Image: Eliciting Student Thinking About Sampling and Variability
Within statistics education, there is a growing interest in understanding students\u27 application of understanding about variability and sampling given the relative lack of research in either area (Shaughnessy, 2007). The task examined in this paper elicited students\u27 knowledge of these concepts within a small-group problem solving task completed by teams of first-year engineering students. In the Nanoroughness task, teams of students designed a procedure for quantifying the roughness of a material surface using digital images generated by atomic force microscopy. The procedure required students to apply statistical methods in order to aggregate the data. The focus of this article is the subsequent analysis of the responses to the task and the questions raised by that analysis.
The Nanoroughness task is unique but critical as a statistical modeling task for two reasons. First, the students needed to use statistical measures to develop a measure that would describe a qualitative characteristic (roughness) without any prompting as to what statistical procedures were relevant. There are different ways to conceptualize roughness of a surface. Sandpaperâs roughness depends on the grain size of the sand. A road may be rough if it has randomly occurring large holes but smoother if the bumps are evenly distributed. The challenge in developing quantitative measures to define qualitative characteristics is that different quantitative analyses emphasize different variables and the students needed to both analyze and apply statistical procedures relevant to the context. For instance, determining which member of a set is the most rough or the least rough will depend on what measurements were selected, and how those measures were analyzed. The second unique characteristic of the task is that the students also needed to define a sampling procedure for an image that would facilitate quantifying the variability in the surface portrayed in the digital image. Usually when students need to take measurements of a population, the population is a discrete set of objects. In this case, the data set was a continuous surface. From the data set, the students need to determine the relevant population (e.g., every point on the surface, every peak on the surface, peaks and valleys). Such continuous populations are not unique within engineering and the sciences and occur in a variety of contexts where characteristics need to be measured and operationally defined.
The task was implemented in a first-year engineering course that served as an introduction to basic tools of engineering with an emphasis on MatLabÂź and ExcelÂź as technological tools. The Nanoroughness task was used in the course to introduce students to the real work of engineers who must not only calculate statistics but also analyze and interpret the results. Our research asked a two-part question. First, what is the quality of student responses to the Nanoroughness task? To answer this we looked at the viability of the model they had created and how well they had explained their procedure for comparing the roughness of images. Second, what statistical models were elicited by the task? We specifically looked at the sampling methods students used and then how the students analyzed the data set they had created. In this paper, we describe the quantitative and qualitative analyses we completed of a sample of student responses
Statistical mechanics approach to the phase unwrapping problem
The use of Mean-Field theory to unwrap principal phase patterns has been
recently proposed. In this paper we generalize the Mean-Field approach to
process phase patterns with arbitrary degree of undersampling. The phase
unwrapping problem is formulated as that of finding the ground state of a
locally constrained, finite size, spin-L Ising model under a non-uniform
magnetic field. The optimization problem is solved by the Mean-Field Annealing
technique. Synthetic experiments show the effectiveness of the proposed
algorithm
On the use of Odonata as ecological indicators
The insect order Odonata, the dragonflies and damselflies, is unique to use as an ecological indicator for water quality because of its close relationship with aquatic ecosystems and relative ease of observation and species-level identification. My goal was to explore ways in which odonates can respond to, and therefore indicate, sites with higher water quality.
Determining where odonates breed as opposed to where they âmerelyâ occur is key to an understanding of the importance of water quality. It has been asserted that one should conclude that an odonate species breeds if and only if physical (exuvia, tenerals) or behavioral (tandem pairing, oviposition) evidence is obtained, yet gathering such evidence requires specialized observational and technical skills. In contrast, reliable observations and counts of adults can be had readily, creating a dilemma over which data to use. For my first chapter, I examined whether adult surveys and reproductive behaviors could predict breeding residency status, represented by presence of tenerals (newly emerged odonates), using a large, multi-year dataset from across Oklahoma. Using an occupancy model combined with piecewise regression, I found thresholds and associated Bayesian credible intervals for a suite of odonate taxa. I found similar general thresholds across species but found specific indicator thresholds exist when examining groups on the family and genus level. Thresholds differed among taxonomic groups and decreased in models that included counts of females rather than just of counts of adults any (or unknown) sex. My results can guide future survey protocol: adult observations can remain the primary focus, which broadens the scope of potential observer skill levels (e.g., citizen scientists) while indirectly ensuring breeding to identify sites for water quality surveys.
For my second chapter, I examined odonate biodiversity at urbanized water features to determine factors that promote species diversity and abundance, with a goal of using findings to make beneficial improvements to park management to increase water quality. I conducted surveys AprilâOctober 2016â2017 at 14 urban sites in central Oklahoma that varied in human use and habitat structure. I compared diversity and species composition among sites and tested which features best predicted higher abundance and species totals. Several variables were good predictors but use of a site for fishing purposes was an overarching indicator of both high species richness and high odonate abundance. Despite higher human use, presence of infrastructure, and increased management of these sites (which are typically negatively associated with biodiversity), odonates (and humans) benefit from maintaining them and ensuring proper water quality persists (i.e., if it is good for fish, it is good for insects)
Enkel intravenös administrering av trimetoprim-sulfadiazin hos neonatala föl
The retrospective part of this study evaluates the susceptibility patterns of bacteria isolated from blood in critically ill foals in Sweden. The most commonly obtained bacteria were Actinobacillus spp. (38 %) and Escherichia coli (27 %). Trimethoprim-sulphonamide (TMS) had good efficacy against most gram negative bacteria with the exception of Klebsiella spp. Among 17 Escherichia coli isolates 94 % were susceptible to trimethoprim-sulphonamide whereas all 24 isolates of Actinobacillus spp. were susceptible to the same substance. The efficacy against gram positive bacteria was more variable.
Two healthy foals (two and three days old) were given a single intravenous (iv) injection of trimethoprim (TMP) â sulphadiazine (SDZ) at a dosage of 2,5 mg TMP/kg bodyweight (bwt) and 12,5 mg SDZ /kg bwt. Blood samples were collected serially during a 24 hour period and plasma concentrations of TMP and SDZ were determined by liquid chromatography tandem mass spectrometry (LCMSMS). The pharmacokinetic parameters of TMP and SDZ from the foals were compared to published data for adult horses. The pharmacokinetic properties of sulphadiazine were equal to those of adult horses with the exception of the area under the curve (AUC0-â) and the mean residence time (MRT) for the three day old foal. These both values were slightly higher than those of adult horses. The pharmacokinetic parameters of TMP from the foals were also similar compared to earlier published values for adult horses. However, the two day old foal had a higher clearance (Cl) for TMP and therefore a lower half life (t1/2), AUC0-â and MRT. The results of the present study indicates that healthy neonatal foals have similar pharmacokinetics of TMP/SDZ as adult horses and it might therefore be possible to use the same dose regimens for foals as for adult horses. However, further studies of more foals are necessary to confirm the result of this pilot study.I den retrospektiva delen av studien anlayserades data avseende resistensmönster för gramnegativa bakterier involverade i neonatal septikemi. Retrospektiva data frĂ„n föl med neonatal septikemi behandlade vid Universitetsdjursjukhuset, Sveriges Lantbruksuniversitet, Uppsala visade att vanligast förekommande agens var Actinobacillus spp. (38 %) och Escherichia coli (27 %). För dessa var resistensen mot trimetoprim-sulfa (TMS) 0 % respektive 6 %. Av de grampositiva bakterierna var streptokocker vanligast och Ă€ven om dessa uppvisade 40 % resistens mot TMS var samtliga isolat sensitiva för penicillin.
TvĂ„ kliniskt friska föl injicerades intravenöst med en enkel dos HippotrimÂź vet. (2,5 mg trimetoprim (TMP) + 12,5 mg sulfadiazine (SDZ) / kg kroppsvikt). Upprepad provtagning frĂ„n respektive föl skedde under 24 timmar, vartefter koncentrationen av TMP och SDZ i plasma analyserades medelst liquid chromatography tandem mass spectrometry (LCMSMS). De farmakokinetiska parametrarna för fölen jĂ€mfördes med vĂ€rden för vuxna hĂ€star. För substansen sulfadiazine förelĂ„g mycket god överrensstĂ€mmelse avseende fölens farmakokinetiska parametrar jĂ€mfört med grĂ€nsvĂ€rden för vuxna hĂ€star och endast arean under kurvan (AUC0-â) och mean residence time (MRT) för det tre dygn gamla fölet lĂ„g strax ovan grĂ€nsvĂ€rdena för adulter. Ăven avseende TMP överrensstĂ€mde flertalet parametrar frĂ„n fölen med grĂ€nsvĂ€rden frĂ„n vuxna hĂ€star, men dĂ„ det tvĂ„ dygn gamla fölet hade ett högre clearance (Cl) erhölls lĂ€gre halveringstid (t1/2), AUC0-â och MRT. Analyserade farmakologiska parametrar tyder pĂ„ att föl fungerar som smĂ„ vuxna hĂ€star, vilket indikerar att samma dosering för TMP/SDZ skulle kunna anvĂ€ndas vid behandling av sĂ„vĂ€l föl som adulta hĂ€star. För att sĂ€kerstĂ€lla resultatet av pilotstudien krĂ€vs dock ytterligare fördjupade studier
Organic molecules in the spectral line survey of Orion KL with the Odin Satellite from 486492 GHz and 541577 GHz
Proceedings of the International Astronomical Union, 2008, v. 4 n. S251, p. 29-30A spectral line survey of Orion KL has been performed over the frequency range of 486492 GHz and 541577 GHz using the Odin satellite. Over 1000 lines have been identified from 40 different molecular species, including several organic compounds such as methyl cyanide (CH3CN), methanol (CH3OH, 13CH3OH), and dimethyl ether (CH3OCH3). © 2008 International Astronomical Union.published_or_final_versio
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