300 research outputs found
Applications of ultra performance liquid chromatography (UPLC) and tandem mass spectrometry for the detection and quantification of cocaine, amphetamine, and opiate derivatives in human meconium
Development and validation of ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) methodologies for the purpose of detecting and quantifying common drugs of abuse in human meconium specimens is described. Meconium is the first stool passed by a newborn infant. Meconium formation occurs over several months of gestation and subsequent toxicological analysis of the specimens can be useful for identifying drugs and other xenobiotics indicative of prenatal drug exposure.;Ultra performance liquid chromatography (UPLC) is an emerging analytical technique which draws upon the principles of chromatography to run separations at higher flow rates for increased speed, while simultaneously achieving superior resolution and sensitivity. Tandem mass spectrometry experiments were performed using a triple quadrupole mass spectrometer equipped with an electrospray ionization (ESI) source operating in positive ion mode. Methodologies were developed and validated to detect and quantify amphetamine, methamphetamine, cocaine, benzoylecgonine, morphine, codeine, hydromorphone, and 6-monoacetylmorphine (6-MAM) in authentic meconium specimens.;Analytes were extracted from the meconium matrix using either a mixed mode solid phase extraction (SPE), or a supported-liquid extraction (SLE) employing columns containing a modified form of diatomaceous earth. Data acquisition was performed using multiple reaction monitoring (MRM) and quantitation of each analyte was performed using a working standard calibration curve. The analytical methodologies were fully validated for the meconium matrix, where linearity, matrix equivalence, selectivity, accuracy, precision, sensitivity, stability, and recovery were evaluated.;Equivalence studies indicated that in all cases, certified drug free whole blood was a suitable matrix for the preparation of working calibration curves. Blank meconium specimens containing analytes at the LOQ, were spiked with various exogenous interferences and analyzed to assess the selectivity of the analytical method. All methodologies were deemed highly selective for the analyte of interest even in the presence of exogenous compounds commonly encountered in forensic specimens. Accuracy, precision, stability, and recovery were assessed at three different analyte concentrations corresponding to the LOQ, the ULOQ, and a concentration point midway between the two. Mean accuracies ranged from 94.6% to 99.6% over the three concentrations for the cocaine/benzoylecgonine methodology while the amphetamine and opiate assays also exhibited high accuracies with mean ranges of 93.6% to 98.4% and 93% to 99.6%, respectively. Inter and intra batch precision data indicated enhanced method precision and reproducibility relative to existing techniques. Intra-batch CV values ranged from 1.6 to 11.8% for the cocaine/benzoylecgonine methodology while inter-batch CV values ranged from 3.9% to 6.2%. Intra-batch CV values ranged from 0.7% to 8.5% for the amphetamine/methamphetamine methodology while inter-batch CV values ranged from 1.9% to 6.2%. The opiate methodology was also highly precise with intra-batch CV values ranging from 1.2% to 10.7% while interbatch CV values ranged from 0.5% to 6.1% across the four analytes. While mean analyte recoveries ranged from 9.3% for benzoylecgonine to 76.3% for 6-monoacetylmorphine, the consistency and reproducibility of the extraction was acceptable for all analytes. Stability studies indicated that all analytes are stable in the meconium matrix when stored at 4°C and subjected to multiple freeze-thaw cycles over a 72 hour period. Limits of detection ranged from 250 pg/mL for methamphetamine, to 2.5 ng/mL for all four opiate analytes. Linear calibration for the cocaine/benzoylecgonine, amphetamine/methamphetamine, and opiate methodologies was achieved over the range of 10--250 ng/mL, 5--500 ng/mL, and 10--500 ng/mL, respectively.;Recent technological advances made in the field of particle chemistry mean that liquid chromatographic separations can be performed at higher flow rates for increased speed without sacrificing resolution or sensitivity. The increased speed, resolution, sensitivity, and separation efficiency afforded by UPLC combined with the inherent selectivity and sensitivity of the tandem mass spectrometer allowed for the accurate quantitation of all 8 analytes in the meconium matrix in a time and cost effective manner. Development and validation of such analytical methodologies will prove beneficial for the identification of prenatal substance abuse which is an ongoing concern across socioeconomic lines
Francisco Mattos (ed.), industrial culture Handbook
An episode of the the U.S. Public Broadcasting Service documentary series P.O.V. titled ‘‘Baby, It’s You’’ (2 June, 1988) captures a glimmer of what is left of that early eighties music-art scene known as ‘‘industrial.’’ In the wake of a newscast detailing new information about the Columbine High School massacre in April, 1999 – a crime initially linked by the press to the ‘‘gothic’’ and «industrial» music consumed by the murderers – the narrator’s voice (Anne Makepeace) invited me to carry t..
A Comparison of Symptom Severity Between University Counseling Center and Community Mental Health Center Clients
The present study compares presenting levels of psychological distress at a university counseling center and a community mental health center. The Brief Symptom Inventory (BSI) was completed by clients at intake, and the results were subjected to statistical analysis. A significant difference was found between the two service units on the Global Symptom Index and all nine scales of the BSI. There were no gender differences in overall levels of psychological distress; however, a difference was found on the interpersonal hostility scale. Implications of the study, as well as limitations and suggestions for future research, are discussed
« Oh my goth! » Sur quelques ouvrages traitant de la scène gothique
Les ouvrages académiques ou para-académiques se caractérisent par un lent processus d’élaboration suivi d’une longue période de consommation. Si l’on s’en tient à ce principe énoncé par John Hartley , on comprend mieux pourquoi, après le choc culturel provoqué par le massacre de Columbine High School (Etats-Unis) en 1999 , il faudra un bon nombre d’années avant de pouvoir valoriser l’avalanche d’études qui tentent de mieux cerner ce qui fait les spécificités de la « culture de l’obscur », plu..
Spatio-temporal influence of tundra snow properties on Ku-band (17.2 GHz) backscatter
During the 2010/11 boreal winter, a distributed set of backscatter measurements was collected using a ground-based Ku-band (17.2 GHz) scatterometer system at 26 open tundra sites. A standard snow-sampling procedure was completed after each scan to evaluate local variability in snow layering, depth, density and water equivalent (SWE) within the scatterometer field of view. The shallow depths and large basal depth hoar encountered presented an opportunity to evaluate backscatter under a set of previously untested conditions. Strong Ku-band response was found with increasing snow depth and snow water equivalent (SWE). In particular, co-polarized vertical backscatter increased by 0.82 dB for every 1 cm increase in SWE (R2 = 0.62). While the result indicated strong potential for Ku-band retrieval of shallow snow properties, it did not characterize the influence of sub-scan variability. An enhanced snow-sampling procedure was introduced to generate detailed characterizations of stratigraphy within the scatterometer field of view using near-infrared photography along the length of a 5m trench. Changes in snow properties along the trench were used to discuss variations in the collocated backscatter response. A pair of contrasting observation sites was used to highlight uncertainties in backscatter response related to short length scale spatial variability in the observed tundra environment
Urban Patterns and Flood Damage in Texas Coastal Watersheds
This study develops a framework to conceptualize and measure multiple urban patterns and examines their relationship with flood damage in Texas coastal watersheds. Development and flood damage impacts are analyzed over a ten year period in 916 watersheds that overlap Texas’ 41 coastal watershed counties using the USGS National Hydrography Dataset. A cross sectional time series regression model is used to determine how changes in these patterns influence the amount of flood damage that occurs in the study area.
Results from the study provide clarity on how different dimensions of urbanization are related to flood damage. Using six landscape metric measurements for three different levels of urban land cover and two measures of residential property location in relation to the rest of the watershed, regression analyses conclude that most urban pattern metrics are significant in influencing the degree of flood damage at a watershed scale. Specifically, increases in percentage of impervious surface increases flood damage, as do most other metrics as they pertain to expansiveness of impervious surface across the landscape. Two metrics (Mean Shape and Average Distance of Residential Property to Water) did not behave as hypothesized; it is believed that mean patch shape was incorrectly hypothesized, and the metric representing average distance to water was measured inappropriately.
The results of the models and the significance and direction of the independent and control variables all provide evidence of the need to take urban form and environmental factors into consideration and an ecosystem-based approach should be taken when engaging in policy and planning activities to reduce residential property damage from flood events
Testing Models of Intrinsic Brightness Variations in Type Ia Supernovae, and their Impact on Measuring Cosmological Parameters
For spectroscopically confirmed Type Ia supernovae we evaluate models of
intrinsic brightness variations with detailed data/Monte Carlo comparisons of
the dispersion in the following quantities: Hubble-diagram scatter, color
difference (B-V-c) between the true B-V color and the fitted color (c) from the
SALT-II light curve model, and photometric redshift residual. The data sample
includes 251 ugriz light curves from the 3-season Sloan Digital Sky Survey-II,
and 191 griz light curves from the Supernova Legacy Survey 3-year data release.
We find that the simplest model of a wavelength-independent (coherent) scatter
is not adequate, and that to describe the data the intrinsic scatter model must
have wavelength-dependent variations. We use Monte Carlo simulations to examine
the standard approach of adding a coherent scatter term in quadrature to the
distance-modulus uncertainty in order to bring the reduced chi2 to unity when
fitting a Hubble diagram. If the light curve fits include model uncertainties
with the correct wavelength dependence of the scatter, we find that the bias on
the dark energy equation of state parameter is negligible. However,
incorrect model uncertainties can lead to a significant bias on the distance
moduli, with up to ~0.05 mag redshift-dependent variation. For the recent SNLS3
cosmology results we estimate that this effect introduces an additional
systematic uncertainty on of ~0.02, well below the total uncertainty.
However, this uncertainty depends on the samples used, and thus this small
-uncertainty is not guaranteed in future cosmology results.Comment: accepted by Ap
2006 SQ372: A Likely Long-Period Comet from the Inner Oort Cloud
We report the discovery of a minor planet (2006 SQ372) on an orbit with a
perihelion of 24 AU and a semimajor axis of 796 AU. Dynamical simulations show
that this is a transient orbit and is unstable on a timescale of 200 Myrs.
Falling near the upper semimajor axis range of the scattered disk and the lower
semimajor axis range of the Oort Cloud, previous membership in either class is
possible. By modeling the production of similar orbits from the Oort Cloud as
well as from the scattered disk, we find that the Oort Cloud produces 16 times
as many objects on SQ372-like orbits as the scattered disk. Given this result,
we believe this to be the most distant long-period comet ever discovered.
Furthermore, our simulation results also indicate that 2000 OO67 has had a
similar dynamical history. Unaffected by the "Jupiter-Saturn Barrier," these
two objects are most likely long-period comets from the inner Oort Cloud
Single or Double Degenerate Progenitors? Searching for Shock Emission in the SDSS-II Type Ia Supernovae
From the set of nearly 500 spectroscopically confirmed type~Ia supernovae and
around 10,000 unconfirmed candidates from SDSS-II, we select a subset of 108
confirmed SNe Ia with well-observed early-time light curves to search for
signatures from shock interaction of the supernova with a companion star. No
evidence for shock emission is seen; however, the cadence and photometric noise
could hide a weak shock signal. We simulate shocked light curves using SN Ia
templates and a simple, Gaussian shock model to emulate the noise properties of
the SDSS-II sample and estimate the detectability of the shock interaction
signal as a function of shock amplitude, shock width, and shock fraction. We
find no direct evidence for shock interaction in the rest-frame -band, but
place an upper limit on the shock amplitude at 9% of supernova peak flux ( mag). If the single degenerate channel dominates type~Ia progenitors,
this result constrains the companion stars to be less than about 6
on the main sequence, and strongly disfavors red giant companions.Comment: 28 pages, 3 figure
Two More Candidate AM Canum Venaticorum (AM CVn) Binaries from the Sloan Digital Sky Survey
AM CVn systems are a select group of ultracompact binaries with the shortest
orbital periods of any known binary subclass; mass-transfer is likely from a
low-mass (partially-)degenerate secondary onto a white dwarf primary, driven by
gravitational radiation. In the past few years, the Sloan Digital Sky Survey
(SDSS) has provided five new AM CVns. Here we report on two further candidates
selected from more recent SDSS data. SDSS J1208+3550 is similar to the earlier
SDSS discoveries, recognized as an AM CVn via its distinctive spectrum which is
dominated by helium emission. From the expanded SDSS Data Release 6 (DR6)
spectroscopic area, we provide an updated surface density estimate for such AM
CVns of order 10^{-3.1} to 10^{-2.5} per deg^2 for 15<g<20.5. In addition, we
present another new candidate AM CVn, SDSS J2047+0008, that was discovered in
the course of followup of SDSS-II supernova candidates. It shows nova-like
outbursts in multi-epoch imaging data; in contrast to the other SDSS AM CVn
discoveries, its (outburst) spectrum is dominated by helium absorption lines,
reminiscent of KL Dra and 2003aw. The variability selection of SDSS J2047+0008
from the 300 deg^2 of SDSS Stripe 82 presages further AM CVn discoveries in
future deep, multicolor, and time-domain surveys such as LSST. The new
additions bring the total SDSS yield to seven AM CVns thus far, a substantial
contribution to this rare subclass, versus the dozen previously known.Comment: 19 pages, 5 figures, 1 table; submitted to A
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