Snapshot hyperspectral imaging probe with principal component analysis and confidence ellipse for classification

NASA Astrophysics Data System (ADS)

Lim, Hoong-Ta; Murukeshan, Vadakke Matham

2017-06-01

Hyperspectral imaging combines imaging and spectroscopy to provide detailed spectral information for each spatial point in the image. This gives a three-dimensional spatial-spatial-spectral datacube with hundreds of spectral images. Probe-based hyperspectral imaging systems have been developed so that they can be used in regions where conventional table-top platforms would find it difficult to access. A fiber bundle, which is made up of specially-arranged optical fibers, has recently been developed and integrated with a spectrograph-based hyperspectral imager. This forms a snapshot hyperspectral imaging probe, which is able to form a datacube using the information from each scan. Compared to the other configurations, which require sequential scanning to form a datacube, the snapshot configuration is preferred in real-time applications where motion artifacts and pixel misregistration can be minimized. Principal component analysis is a dimension-reducing technique that can be applied in hyperspectral imaging to convert the spectral information into uncorrelated variables known as principal components. A confidence ellipse can be used to define the region of each class in the principal component feature space and for classification. This paper demonstrates the use of the snapshot hyperspectral imaging probe to acquire data from samples of different colors. The spectral library of each sample was acquired and then analyzed using principal component analysis. Confidence ellipse was then applied to the principal components of each sample and used as the classification criteria. The results show that the applied analysis can be used to perform classification of the spectral data acquired using the snapshot hyperspectral imaging probe.

Phase-Enhanced 3D Snapshot ISAR Imaging and Interferometric SAR

DTIC Science & Technology

2009-12-28

generalized technique requires the precession angle 9p be relatively small [see liq. (28)|. However, the noncoherent snapshot image equations remain...valid beyond this precession limit, and the unique sampling grid developed is still very useful for 3D imaging of the noncoherent snapshot equation

Water Isotopes in the GISS GCM: History, Applications and Potential

NASA Astrophysics Data System (ADS)

Schmidt, G. A.; LeGrande, A. N.; Field, R. D.; Nusbaumer, J. M.

2017-12-01

Water isotopes have been incorporated in the GISS GCMs since the pioneering work of Jean Jouzel in the 1980s. Since 2005, this functionality has been maintained within the master branch of the development code and has been usable (and used) in all subsequent versions. This has allowed a wide variety of applications, across multiple time-scales and interests, to be tackled coherently. Water isotope tracers have been used to debug the atmospheric model code, tune parameterisations of moist processes, assess the isotopic fingerprints of multiple climate drivers, produce forward models for remotely sensed isotope products, and validate paleo-climate interpretations from the last millennium to the Eocene. We will present an overview of recent results involving isotope tracers, including improvements in models for the isotopic fractionation processes themselves, and demonstrate the potential for using these tracers and models more systematically in paleo-climate reconstructions and investigations of the modern hydrological cycle.

Electric Vehicles--A Historical Snapshot

ERIC Educational Resources Information Center

Kraft, Thomas E.

2012-01-01

Most people don't realize that the history of electric vehicles (EVs) predates the Civil War. This article provides a historical snapshot of EVs to spark the interest of both teachers and students in this important transportation technology.

Introduction to Chemistry and Applications in Nature of Mass Independent Isotope Effects Special Feature

PubMed Central

Thiemens, Mark H.

2013-01-01

Stable isotope ratio variations are regulated by physical and chemical laws. These rules depend on a relation with mass differences between isotopes. New classes of isotope variation effects that deviate from mass dependent laws, termed mass independent isotope effects, were discovered in 1983 and have a wide range of applications in basic chemistry and nature. In this special edition, new applications of these effects to physical chemistry, solar system origin models, terrestrial atmospheric and biogenic evolution, polar paleo climatology, snowball earth geology, and present day atmospheric sciences are presented. PMID:24167299

Introduction to chemistry and applications in nature of mass independent isotope effects special feature.

PubMed

Thiemens, Mark H

2013-10-29

Stable isotope ratio variations are regulated by physical and chemical laws. These rules depend on a relation with mass differences between isotopes. New classes of isotope variation effects that deviate from mass dependent laws, termed mass independent isotope effects, were discovered in 1983 and have a wide range of applications in basic chemistry and nature. In this special edition, new applications of these effects to physical chemistry, solar system origin models, terrestrial atmospheric and biogenic evolution, polar paleo climatology, snowball earth geology, and present day atmospheric sciences are presented.

Generalization of the Lyot filter and its application to snapshot spectral imaging.

PubMed

Gorman, Alistair; Fletcher-Holmes, David William; Harvey, Andrew Robert

2010-03-15

A snapshot multi-spectral imaging technique is described which employs multiple cascaded birefringent interferometers to simultaneously spectrally filter and demultiplex multiple spectral images onto a single detector array. Spectral images are recorded directly without the need for inversion and without rejection of light and so the technique offers the potential for high signal-to-noise ratio. An example of an eight-band multi-spectral movie sequence is presented; we believe this is the first such demonstration of a technique able to record multi-spectral movie sequences without the need for computer reconstruction.

CALiPER Snapshot Report: Troffers

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

2016-12-01

Snapshot reports use data from DOE's LED Lighting Facts product list to compare the LED performance to standard technologies, and are designed to help lighting retailers, distributors, designers, utilities, energy efficiency program sponsors, and other stakeholders understand the current state of the LED market and its trajectory.

SnapShot: The Bacterial Cytoskeleton.

PubMed

Fink, Gero; Szewczak-Harris, Andrzej; Löwe, Jan

2016-07-14

Most bacteria and archaea contain filamentous proteins and filament systems that are collectively known as the bacterial cytoskeleton, though not all of them are cytoskeletal, affect cell shape, or maintain intracellular organization. To view this SnapShot, open or download the PDF. Copyright © 2016. Published by Elsevier Inc.

Maximum bandwidth snapshot channeled imaging polarimeter with polarization gratings

NASA Astrophysics Data System (ADS)

LaCasse, Charles F.; Redman, Brian J.; Kudenov, Michael W.; Craven, Julia M.

2016-05-01

Compact snapshot imaging polarimeters have been demonstrated in literature to provide Stokes parameter estimations for spatially varying scenes using polarization gratings. However, the demonstrated system does not employ aggressive modulation frequencies to take full advantage of the bandwidth available to the focal plane array. A snapshot imaging Stokes polarimeter is described and demonstrated through results. The simulation studies the challenges of using a maximum bandwidth configuration for a snapshot polarization grating based polarimeter, such as the fringe contrast attenuation that results from higher modulation frequencies. Similar simulation results are generated and compared for a microgrid polarimeter. Microgrid polarimeters are instruments where pixelated polarizers are superimposed onto a focal plan array, and this is another type of spatially modulated polarimeter, and the most common design uses a 2x2 super pixel of polarizers which maximally uses the available bandwidth of the focal plane array.

High-resolution structure of viruses from random diffraction snapshots

PubMed Central

Hosseinizadeh, A.; Schwander, P.; Dashti, A.; Fung, R.; D'Souza, R. M.; Ourmazd, A.

2014-01-01

The advent of the X-ray free-electron laser (XFEL) has made it possible to record diffraction snapshots of biological entities injected into the X-ray beam before the onset of radiation damage. Algorithmic means must then be used to determine the snapshot orientations and thence the three-dimensional structure of the object. Existing Bayesian approaches are limited in reconstruction resolution typically to 1/10 of the object diameter, with the computational expense increasing as the eighth power of the ratio of diameter to resolution. We present an approach capable of exploiting object symmetries to recover three-dimensional structure to high resolution, and thus reconstruct the structure of the satellite tobacco necrosis virus to atomic level. Our approach offers the highest reconstruction resolution for XFEL snapshots to date and provides a potentially powerful alternative route for analysis of data from crystalline and nano-crystalline objects. PMID:24914154

High-resolution structure of viruses from random diffraction snapshots.

PubMed

Hosseinizadeh, A; Schwander, P; Dashti, A; Fung, R; D'Souza, R M; Ourmazd, A

2014-07-17

The advent of the X-ray free-electron laser (XFEL) has made it possible to record diffraction snapshots of biological entities injected into the X-ray beam before the onset of radiation damage. Algorithmic means must then be used to determine the snapshot orientations and thence the three-dimensional structure of the object. Existing Bayesian approaches are limited in reconstruction resolution typically to 1/10 of the object diameter, with the computational expense increasing as the eighth power of the ratio of diameter to resolution. We present an approach capable of exploiting object symmetries to recover three-dimensional structure to high resolution, and thus reconstruct the structure of the satellite tobacco necrosis virus to atomic level. Our approach offers the highest reconstruction resolution for XFEL snapshots to date and provides a potentially powerful alternative route for analysis of data from crystalline and nano-crystalline objects.

Analysis and application of heavy isotopes in the environment

NASA Astrophysics Data System (ADS)

Steier, Peter; Dellinger, Franz; Forstner, Oliver; Golser, Robin; Knie, Klaus; Kutschera, Walter; Priller, Alfred; Quinto, Francesca; Srncik, Michaela; Terrasi, Filippo; Vockenhuber, Christof; Wallner, Anton; Wallner, Gabriele; Wild, Eva Maria

2010-04-01

A growing number of AMS laboratories are pursuing applications of actinides. We discuss the basic requirements of the AMS technique of heavy (i.e., above ˜150 amu) isotopes, present the setup at the Vienna Environmental Research Accelerator (VERA) which is especially well suited for the isotope 236U, and give a comparison with other AMS facilities. Special emphasis will be put on elaborating the effective detection limits for environmental samples with respect to other mass spectrometric methods. At VERA, we have carried out measurements for radiation protection and environmental monitoring ( 236U, 239,240,241,242,244Pu), astrophysics ( 182Hf, 236U, 244Pu, 247Cm), nuclear physics, and a search for long-lived super-heavy elements ( Z > 100). We are pursuing the environmental distribution of 236U, as a basis for geological applications of natural 236U.

Transient competitive complexation in biological kinetic isotope fractionation explains non-steady isotopic effects: Theory and application to denitrification in soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maggi, F.M.; Riley, W.J.

2009-06-01

The theoretical formulation of biological kinetic reactions in isotopic applications often assume first-order or Michaelis-Menten-Monod kinetics under the quasi-steady-state assumption to simplify the system kinetics. However, isotopic e ects have the same order of magnitude as the potential error introduced by these simpli cations. Both formulations lead to a constant fractionation factor which may yield incorrect estimations of the isotopic effect and a misleading interpretation of the isotopic signature of a reaction. We have analyzed the isotopic signature of denitri cation in biogeochemical soil systems by Menyailo and Hungate [2006], where high {sup 15}N{sub 2}O enrichment during N{sub 2}O productionmore » and inverse isotope fractionation during N{sub 2}O consumption could not be explained with first-order kinetics and the Rayleigh equation, or with the quasi-steady-state Michaelis-Menten-Monod kinetics. When the quasi-steady-state assumption was relaxed, transient Michaelis-Menten-Monod kinetics accurately reproduced the observations and aided in interpretation of experimental isotopic signatures. These results may imply a substantial revision in using the Rayleigh equation for interpretation of isotopic signatures and in modeling biological kinetic isotope fractionation with first-order kinetics or quasi-steady-state Michaelis-Menten-Monod kinetics.« less

Stable isotopic variation in tropical forest plants for applications in primatology.

PubMed

Blumenthal, Scott A; Rothman, Jessica M; Chritz, Kendra L; Cerling, Thure E

2016-10-01

Stable isotope analysis is a promising tool for investigating primate ecology although nuanced ecological applications remain challenging, in part due to the complex nature of isotopic variability in plant-animal systems. The aim of this study is to investigate sources of carbon and nitrogen isotopic variation at the base of primate food webs that reflect aspects of primate ecology. The majority of primates inhabit tropical forest ecosystems, which are dominated by C3 vegetation. We used stable isotope ratios in plants from Kibale National Park, Uganda, a well-studied closed-canopy tropical forest, to investigate sources of isotopic variation among C3 plants related to canopy stratification, leaf age, and plant part. Unpredictably, our results demonstrate that vertical stratification within the canopy does not explain carbon or nitrogen isotopic variation in leaves. Leaf age can be a significant source of isotopic variation, although the direction and magnitude of this difference is not consistent across tree species. Some plant parts are clearly differentiated in carbon and nitrogen isotopic composition, particularly leaves compared to non-photosynthetic parts such as reproductive parts and woody stem parts. Overall, variation in the isotopic composition of floral communities, plant species, and plant parts demonstrates that stable isotope studies must include analysis of local plant species and parts consumed by the primates under study from within the study area. Am. J. Primatol. 78:1041-1054, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Modeling of water isotopes in polar regions and application to ice core studies

NASA Astrophysics Data System (ADS)

Jouzel, J.

2012-04-01

Willi Dansgaard spear-headed the use of the stable isotopes of water in climatology and palaeoclimatology especially as applied to deep ice cores for which measurements of the oxygen and hydrogen isotope ratios remain the key tools for reconstructing continuous palaeotemperature records. In the line of his pioneering work on "Stable isotopes in precipitation" published in Tellus in 1964, I will review how isotopic models, either Rayleigh type or based on the implementation of water isotopes in General Circulation Models, have developed and been used for applications in polar ice core studies. This will include a discussion of the conventional approach for interpreting water isotopes in ice cores and of additional information provided by measurements of the deuterium excess and more recently of the 17O-excess.

APPLICATION OF STABLE ISOTOPE TECHNIQUES TO AIR POLLUTION RESEARCH

EPA Science Inventory

Stable isotope techniques provide a robust, yet under-utilized tool for examining pollutant effects on plant growth and ecosystem function. Here, we survey a range of mixing model, physiological and system level applications for documenting pollutant effects. Mixing model examp...

Snapshots of Interactive Multimedia at Work Across the Curriculum in Deaf Education: Implications for Public Address Training

ERIC Educational Resources Information Center

Parton, Becky Sue

2006-01-01

A review of the literature yields many intriguing applications of interactive multimedia technology that can be seen through a series of "snapshots" describing current projects and initiatives for deaf education. The five main categories chosen to represent these activities are: instructional design, communication bridges, skill development…

American Youth: A Statistical Snapshot.

ERIC Educational Resources Information Center

Wetzel, James R.

This document presents a statistics snapshot of young people, aged 15 to 24 years. It provides a broad overview of trends documenting the direction of changes in social behavior and economic circumstances. The projected decline in the total number of youth from 43 million in 1980 to 35 million in 1995 will affect marriage and childbearing…

Stable Chlorine Isotope Study: Application to Early Solar System Materials

NASA Technical Reports Server (NTRS)

Mala,ira. M/; Nyquist, L. E.; Reese, Y.; Shih, C-Y; Fujitani, T.; Okano, O.

2010-01-01

other [4], some authors have claimed that the 37Cl/35Cl ratio of geological samples obtained by TIMS technique are, in general, misleadingly too high and variable compared to those of IRMS [3]. For eample, almost no differences of Cl isotope composition were observed among mantle materials and carbonaceous meteorites by [3]. On the other hand, according to more recent IRMS work [2], significant Cl isotope variations are confirmed for mantle materials. Therefore, additional careful investigation of Cl isotope analyses are now required to confirm real chlorine isotope variations for planetary materials including carbonaceous chondrites [5]. In order to clarify the stable chlorine isotope features of early solar system materials, we have initiated development of the TIMS technique at NASA JSC applicable to analysis of small amounts of meteoritic and planetary materials. We report here the current status of chlorine isotope analysis at NASA JSC.

Biomedical research applications of electromagnetically separated enriched stable isotopes

NASA Astrophysics Data System (ADS)

Lambrecht, R. M.

The current and projected annual requirements through 1985 for stable isotopes enriched by electromagnetic separation methods were reviewed for applications in various types of biomedical research: (1) medical radiosiotope production, labeled compounds, and potential radio-pharmaceuticals; (2) nutrition, food science, and pharmacology: (3) metallobiochemistry and environmental toxicology; (4) nuclear magnetic resonance, electron paramagnetic resonance, and moessbauer spectroscopy in biochemical, biophysical, and biomedical research; and (5) miscellaneous advances in radioactive and nonradioactive tracer technology. Radioisotopes available from commercial sources or routinely used in clinical nuclear medicine were excluded. Current requirements for enriched stable isotopes in biomedical research are not being satisfied. Severe shortages exist for Mg 26, Ca 43, Zn 70, Se 76, Se 77, Se 78, Pd 102, Cd 111, Cd 113, and Os 190. Many interesting and potentially important investigations in biomedical research require small quantities of specific elements at high isotopic enrichments.

Imaging of blood cells based on snapshot Hyper-Spectral Imaging systems

NASA Astrophysics Data System (ADS)

Robison, Christopher J.; Kolanko, Christopher; Bourlai, Thirimachos; Dawson, Jeremy M.

2015-05-01

Snapshot Hyper-Spectral imaging systems are capable of capturing several spectral bands simultaneously, offering coregistered images of a target. With appropriate optics, these systems are potentially able to image blood cells in vivo as they flow through a vessel, eliminating the need for a blood draw and sample staining. Our group has evaluated the capability of a commercial Snapshot Hyper-Spectral imaging system, the Arrow system from Rebellion Photonics, in differentiating between white and red blood cells on unstained blood smear slides. We evaluated the imaging capabilities of this hyperspectral camera; attached to a microscope at varying objective powers and illumination intensity. Hyperspectral data consisting of 25, 443x313 hyperspectral bands with ~3nm spacing were captured over the range of 419 to 494nm. Open-source hyper-spectral data cube analysis tools, used primarily in Geographic Information Systems (GIS) applications, indicate that white blood cells features are most prominent in the 428-442nm band for blood samples viewed under 20x and 50x magnification over a varying range of illumination intensities. These images could potentially be used in subsequent automated white blood cell segmentation and counting algorithms for performing in vivo white blood cell counting.

MIR hollow waveguide (HWG) isotope ratio analyzer for environmental applications

NASA Astrophysics Data System (ADS)

Wang, Zhenyou; Zhuang, Yan; Deev, Andrei; Wu, Sheng

2017-05-01

An advanced commercial Mid-InfraRed Isotope Ratio (IR2) analyzer was developed in Arrow Grand Technologies based on hollow waveguide (HWG) as the sample tube. The stable carbon isotope ratio, i.e. δ13C, was obtained by measuring the selected CO2 absorption peaks in the MIR. Combined with a GC and a combustor, it has been successfully employed to measure compound specific δ13C isotope ratios in the field. By using both the 1- pass HWG and 5-path HWG, we are able to measure δ13C isotope ratio at a broad CO2 concentration of 300 ppm-37,500 ppm. Here, we demonstrate its applications in environmental studies. The δ13C isotope ratio and concentration of CO2 exhaled by soil samples was measured in real time with the isotope analyzer. The concentration was found to change with the time. We also convert the Dissolved Inorganic Carbon (DIC) into CO2, and then measure the δ13C isotope ratio with an accuracy of better than 0.3 ‰ (1 σ) with a 6 min test time and 1 ml sample usage. Tap water, NaHCO3 solvent, coca, and even beer were tested. Lastly, the 13C isotope ratio of CO2 exhaled by human beings was obtained <10 seconds after simply blowing the exhaled CO2 into a tube with an accuracy of 0.5‰ (1 σ) without sample preconditioning. In summary, a commercial HWG isotope analyzer was demonstrated to be able to perform environmental and health studies with a high accuracy ( 0.3 ‰/Hz1/2 1 σ), fast sampling rate (up to 10 Hz), low sample consumption ( 1 ml), and broad CO2 concentration range (300 ppm-37,500 ppm).

Visual Snapshots of Intracellular Kinase Activity At The Onset of Mitosis

PubMed Central

Dai, Zhaohua; Dulyaninova, Natalya G.; Kumar, Sanjai; Bresnick, Anne R.; Lawrence, David S.

2007-01-01

Summary Visual snapshots of intracellular kinase activity can be acquired with exquisite temporal control using a light-activatable (caged) sensor, thereby providing a means to interrogate enzymatic activity at any point during the cell division cycle. Robust protein kinase activity transpires just prior to, but not immediately following, nuclear envelope breakdown (NEB). Furthermore, kinase activity is required for progression from prophase into metaphase. Finally, the application of selective protein kinase C (PKC) inhibitors, in combination with the caged sensor, correlates the action of the PKC β isoform with subsequent NEB. PMID:18022564

CALiPER Snapshot Report: Industrial Luminaires

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

2017-03-01

Snapshot reports use data from DOE's LED Lighting Facts product list to compare the LED performance to standard technologies, and are designed to help lighting retailers, distributors, designers, utilities, energy efficiency program sponsors, and other stakeholders understand the current state of the LED market and its trajectory.

Managing Spatial Selections With Contextual Snapshots

PubMed Central

Mindek, P; Gröller, M E; Bruckner, S

2014-01-01

Spatial selections are a ubiquitous concept in visualization. By localizing particular features, they can be analysed and compared in different views. However, the semantics of such selections often depend on specific parameter settings and it can be difficult to reconstruct them without additional information. In this paper, we present the concept of contextual snapshots as an effective means for managing spatial selections in visualized data. The selections are automatically associated with the context in which they have been created. Contextual snapshots can also be used as the basis for interactive integrated and linked views, which enable in-place investigation and comparison of multiple visual representations of data. Our approach is implemented as a flexible toolkit with well-defined interfaces for integration into existing systems. We demonstrate the power and generality of our techniques by applying them to several distinct scenarios such as the visualization of simulation data, the analysis of historical documents and the display of anatomical data. PMID:25821284

Snapshot hyperspectral retinal imaging using compact spectral resolving detector array.

PubMed

Li, Hao; Liu, Wenzhong; Dong, Biqin; Kaluzny, Joel V; Fawzi, Amani A; Zhang, Hao F

2017-06-01

Hyperspectral retinal imaging captures the light spectrum from each imaging pixel. It provides spectrally encoded retinal physiological and morphological information, which could potentially benefit diagnosis and therapeutic monitoring of retinal diseases. The key challenges in hyperspectral retinal imaging are how to achieve snapshot imaging to avoid motions between the images from multiple spectral bands, and how to design a compact snapshot imager suitable for clinical use. Here, we developed a compact, snapshot hyperspectral fundus camera for rodents using a novel spectral resolving detector array (SRDA), on which a thin-film Fabry-Perot cavity filter was monolithically fabricated on each imaging pixel. We achieved hyperspectral retinal imaging with 16 wavelength bands (460 to 630 nm) at 20 fps. We also demonstrated false-color vessel contrast enhancement and retinal oxygen saturation (sO 2 ) measurement through spectral analysis. This work could potentially bring hyperspectral retinal imaging from bench to bedside. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multi-factorial in vivo stable isotope fractionation: causes, correlations, consequences and applications.

PubMed

Schmidt, Hanns-Ludwig; Robins, Richard J; Werner, Roland A

2015-01-01

Many physical and chemical processes in living systems are accompanied by isotope fractionation on H, C, N, O and S. Although kinetic or thermodynamic isotope effects are always the basis, their in vivo manifestation is often modulated by secondary influences. These include metabolic branching events or metabolite channeling, metabolite pool sizes, reaction mechanisms, anatomical properties and compartmentation of plants and animals, and climatological or environmental conditions. In the present contribution, the fundamentals of isotope effects and their manifestation under in vivo conditions are outlined. The knowledge about and the understanding of these interferences provide a potent tool for the reconstruction of physiological events in plants and animals, their geographical origin, the history of bulk biomass and the biosynthesis of defined representatives. It allows the use of isotope characteristics of biomass for the elucidation of biochemical pathways and reaction mechanisms and for the reconstruction of climatic, physiological, ecological and environmental conditions during biosynthesis. Thus, it can be used for the origin and authenticity control of food, the study of ecosystems and animal physiology, the reconstruction of present and prehistoric nutrition chains and paleaoclimatological conditions. This is demonstrated by the outline of fundamental and application-orientated examples for all bio-elements. The aim of the review is to inform (advanced) students from various disciplines about the whole potential and the scope of stable isotope characteristics and fractionations and to provide them with a comprehensive introduction to the literature on fundamental aspects and applications.

Snapshot hyperspectral fovea vision system (HyperVideo)

NASA Astrophysics Data System (ADS)

Kriesel, Jason; Scriven, Gordon; Gat, Nahum; Nagaraj, Sheela; Willson, Paul; Swaminathan, V.

2012-06-01

The development and demonstration of a new snapshot hyperspectral sensor is described. The system is a significant extension of the four dimensional imaging spectrometer (4DIS) concept, which resolves all four dimensions of hyperspectral imaging data (2D spatial, spectral, and temporal) in real-time. The new sensor, dubbed "4×4DIS" uses a single fiber optic reformatter that feeds into four separate, miniature visible to near-infrared (VNIR) imaging spectrometers, providing significantly better spatial resolution than previous systems. Full data cubes are captured in each frame period without scanning, i.e., "HyperVideo". The current system operates up to 30 Hz (i.e., 30 cubes/s), has 300 spectral bands from 400 to 1100 nm (~2.4 nm resolution), and a spatial resolution of 44×40 pixels. An additional 1.4 Megapixel video camera provides scene context and effectively sharpens the spatial resolution of the hyperspectral data. Essentially, the 4×4DIS provides a 2D spatially resolved grid of 44×40 = 1760 separate spectral measurements every 33 ms, which is overlaid on the detailed spatial information provided by the context camera. The system can use a wide range of off-the-shelf lenses and can either be operated so that the fields of view match, or in a "spectral fovea" mode, in which the 4×4DIS system uses narrow field of view optics, and is cued by a wider field of view context camera. Unlike other hyperspectral snapshot schemes, which require intensive computations to deconvolve the data (e.g., Computed Tomographic Imaging Spectrometer), the 4×4DIS requires only a linear remapping, enabling real-time display and analysis. The system concept has a range of applications including biomedical imaging, missile defense, infrared counter measure (IRCM) threat characterization, and ground based remote sensing.

Optimization of compressive 4D-spatio-spectral snapshot imaging

NASA Astrophysics Data System (ADS)

Zhao, Xia; Feng, Weiyi; Lin, Lihua; Su, Wu; Xu, Guoqing

2017-10-01

In this paper, a modified 3D computational reconstruction method in the compressive 4D-spectro-volumetric snapshot imaging system is proposed for better sensing spectral information of 3D objects. In the design of the imaging system, a microlens array (MLA) is used to obtain a set of multi-view elemental images (EIs) of the 3D scenes. Then, these elemental images with one dimensional spectral information and different perspectives are captured by the coded aperture snapshot spectral imager (CASSI) which can sense the spectral data cube onto a compressive 2D measurement image. Finally, the depth images of 3D objects at arbitrary depths, like a focal stack, are computed by inversely mapping the elemental images according to geometrical optics. With the spectral estimation algorithm, the spectral information of 3D objects is also reconstructed. Using a shifted translation matrix, the contrast of the reconstruction result is further enhanced. Numerical simulation results verify the performance of the proposed method. The system can obtain both 3D spatial information and spectral data on 3D objects using only one single snapshot, which is valuable in the agricultural harvesting robots and other 3D dynamic scenes.

Digital Technology Snapshot of the Literacy and Essential Skills Field 2013. Summary Report

ERIC Educational Resources Information Center

Trottier, Vicki

2013-01-01

From January to March 2013, "Canadian Literacy and Learning Network" (CLLN) conducted a snapshot to provide information about how digital technology tools are being used in the Literacy and Essential Skills (L/ES) field. The snapshot focused primarily on digital tools and activities that meet the organizational needs of provincial and…

A snapshot attractor view of the advection of inertial particles in the presence of history force

NASA Astrophysics Data System (ADS)

Guseva, Ksenia; Daitche, Anton; Tél, Tamás

2017-06-01

We analyse the effect of the Basset history force on the sedimentation or rising of inertial particles in a two-dimensional convection flow. We find that the concept of snapshot attractors is useful to understand the extraordinary slow convergence due to long-term memory: an ensemble of particles converges exponentially fast towards a snapshot attractor, and this attractor undergoes a slow drift for long times. We demonstrate for the case of a periodic attractor that the drift of the snapshot attractor can be well characterized both in the space of the fluid and in the velocity space. For the case of quasiperiodic and chaotic dynamics we propose the use of the average settling velocity of the ensemble as a distinctive measure to characterize the snapshot attractor and the time scale separation corresponding to the convergence towards the snapshot attractor and its own slow dynamics.

Engaging with Families in Out-of-School Time Learning. Out-of-School Time Evaluation Snapshot. Number 4

ERIC Educational Resources Information Center

Harvard University Harvard Family Research Project, 2004

2004-01-01

Harvard Family Research Project's series of Out-of-School Time Evaluation Snapshots distills the wealth of information compiled in our Out-of-School Time Program Evaluation Database into a single report. Each Snapshot examines a specific aspect of out-of-school time (OST) evaluation. This Snapshot provides an overview of how researchers are…

A Snapshot of Philadelphia's Accelerated Schools

ERIC Educational Resources Information Center

Edmunds, Kimberly; Fonseca, Ean

2011-01-01

This snapshot is a guide to the School District of Philadelphia's (the District's) 13 accelerated high schools in the 2010-11 school year. The accelerated high schools were the result of a partnership between the District and Project U-Turn, a city-wide coalition dedicated to reducing student drop-out and increasing graduation rates and readiness…

Review: Current applications and challenges for liquid chromatography coupled to isotope ratio mass spectrometry (LC/IRMS).

PubMed

Godin, Jean-Philippe; McCullagh, James S O

2011-10-30

High-precision isotope analysis is recognized as an essential research tool in many fields of study. Until recently, continuous flow isotope ratio mass spectrometry (CF-IRMS) was available via an elemental analyzer or a gas chromatography inlet system for compound-specific analysis of light stable isotopes. In 2004, however, an interface that coupled liquid chromatography with IRMS (LC/IRMS) became commercially available for the first time. This brought the capability for new areas of application, in particular enabling compound-specific δ(13)C analysis of non-volatile, aqueous soluble, compounds from complex mixtures. The interface design brought with it several analytical constraints, however, in particular a lack of compatibility with certain types of chromatography as well as limited flow rates and mobile phase compositions. Routine LC/IRMS methods have, however, been established for measuring the δ(13)C isotopic ratios of underivatized individual compounds for application in archeology, nutrition and physiology, geochemistry, hydrology, soil science and food authenticity. Seven years after its introduction, we review the technical advances and constraints, methodological developments and new applications of liquid chromatography coupled to isotope ratio mass spectrometry. Copyright © 2011 John Wiley & Sons, Ltd.

CALiPER Snapshot Report: Outdoor Area Lighting

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

2016-09-30

Snapshot reports use data from DOE's LED Lighting Facts product list to compare the LED performance to standard technologies, and are designed to help lighting retailers, distributors, designers, utilities, energy efficiency program sponsors, and other stakeholders understand the current state of the LED market and its trajectory.

Iron and nickel isotope fractionation by diffusion, with applications to iron meteorites

NASA Astrophysics Data System (ADS)

Watson, Heather C.; Richter, Frank; Liu, Ankun; Huss, Gary R.

2016-10-01

Mass-dependent, kinetic fractionation of isotopes through processes such as diffusion can result in measurable isotopic signatures. When these signatures are retained in geologic materials, they can be used to help interpret their thermal histories. The mass dependence of the diffusion coefficient of isotopes 1 and 2 can be written as (D1 /D2) =(m2 /m1) β, where D1 and D2 are the diffusion coefficients of m1 and m2 respectively, and β is an empirical coefficient that relates the two ratios. Experiments have been performed to measure β in the Fe-Ni alloy system. Diffusion couple experiments between pure Fe and Ni metals were run in a piston cylinder at 1300-1400 °C and 1 GPa. Concentration and isotopic profiles were measured by electron microprobe and ion microprobe respectively. We find that a single β coefficient of β = 0.32 ± 0.04 can describe the isotopic effect in all experiments. This result is comparable to the isotope effect determined in many other similar alloy systems. The new β coefficient is used in a model of the isotopic profiles to be expected during the Widmanstätten pattern formation in iron meteorites. The results are consistent with previous estimates of the cooling rate of the iron meteorite Toluca. The application of isotopic constraints based on these results in addition to conventional cooling rate models could provide a more robust picture of the thermal history of these early planetary bodies.

The Role of "Family Snapshots" in Teaching Art History within a Dialogic Pedagogy

ERIC Educational Resources Information Center

Baxter, Kristin

2012-01-01

Studying images of families in works of art and in snapshots is compelling, and the author wondered if looking at both types of images side by side might help students understand both kinds of images more fully. Snapshots often prompt detailed and vivid stories among family members and friends. Therefore, she wondered if dialogue about snapshots…

An open source Bayesian Monte Carlo isotope mixing model with applications in Earth surface processes

NASA Astrophysics Data System (ADS)

Arendt, Carli A.; Aciego, Sarah M.; Hetland, Eric A.

2015-05-01

The implementation of isotopic tracers as constraints on source contributions has become increasingly relevant to understanding Earth surface processes. Interpretation of these isotopic tracers has become more accessible with the development of Bayesian Monte Carlo (BMC) mixing models, which allow uncertainty in mixing end-members and provide methodology for systems with multicomponent mixing. This study presents an open source multiple isotope BMC mixing model that is applicable to Earth surface environments with sources exhibiting distinct end-member isotopic signatures. Our model is first applied to new δ18O and δD measurements from the Athabasca Glacier, which showed expected seasonal melt evolution trends and vigorously assessed the statistical relevance of the resulting fraction estimations. To highlight the broad applicability of our model to a variety of Earth surface environments and relevant isotopic systems, we expand our model to two additional case studies: deriving melt sources from δ18O, δD, and 222Rn measurements of Greenland Ice Sheet bulk water samples and assessing nutrient sources from ɛNd and 87Sr/86Sr measurements of Hawaiian soil cores. The model produces results for the Greenland Ice Sheet and Hawaiian soil data sets that are consistent with the originally published fractional contribution estimates. The advantage of this method is that it quantifies the error induced by variability in the end-member compositions, unrealized by the models previously applied to the above case studies. Results from all three case studies demonstrate the broad applicability of this statistical BMC isotopic mixing model for estimating source contribution fractions in a variety of Earth surface systems.

Snapshot imaging polarimeters using spatial modulation

NASA Astrophysics Data System (ADS)

Luo, Haitao

The recent demonstration of a novel snapshot imaging polarimeter using the fringe modulation technique shows a promise in building a compact and moving-parts-free device. As just demonstrated in principle, this technique has not been adequately studied. In the effort of advancing this technique, we build a complete theory framework that can address the key issues regarding the polarization aberrations caused by using the functional elements. With this model, we can have the necessary knowledge in designing, analyzing and optimizing the systems. Also, we propose a broader technique that uses arbitrary modulation instead of sinusoidal fringes, which can give us more engineering freedom and can be the solution of achromatizing the system. In the hardware aspect, several important progresses are made. We extend the polarimeter technique from visible to middle wavelength infrared by using the yttrium vanadate crystals. Also, we incorporate a Savart Plate polarimter into a fundus camera to measure the human eye's retinal retardance, useful information for glaucoma diagnosis. Thirdly, a world-smallest imaging polarimeter is proposed and demonstrated, which may open many applications in security, remote sensing and bioscience.

Application of neodymium isotope ratio measurements for the origin assessment of uranium ore concentrates.

PubMed

Krajkó, Judit; Varga, Zsolt; Yalcintas, Ezgi; Wallenius, Maria; Mayer, Klaus

2014-11-01

A novel procedure has been developed for the measurement of (143)Nd/(144)Nd isotope ratio in various uranium-bearing materials, such as uranium ores and ore concentrates (UOC) in order to evaluate the usefulness and applicability of variations of (143)Nd/(144)Nd isotope ratio for provenance assessment in nuclear forensics. Neodymium was separated and pre-concentrated by extraction chromatography and then the isotope ratios were measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The method was validated by the measurement of standard reference materials (La Jolla, JB-2 and BCR-2) and the applicability of the procedure was demonstrated by the analysis of uranium samples of world-wide origin. The investigated samples show distinct (143)Nd/(144)Nd ratio depending on the ore type, deposit age and Sm/Nd ratio. Together with other characteristics of the material in question, the Nd isotope ratio is a promising signature for nuclear forensics and suggests being indicative of the source material, the uranium ore. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Examining Social Acceptance & Rejection. FPG Snapshot #44

ERIC Educational Resources Information Center

FPG Child Development Institute, 2007

2007-01-01

This FPG Snapshot summarizes the findings of a study, published in the November 2006 issue of the "Journal of Educational Psychology," that examined whether children with disabilities are accepted or rejected by their classmates in inclusive classrooms. Specifically, the study examined two sets of related questions: (1) Are individual…

Pressure estimation from single-snapshot tomographic PIV in a turbulent boundary layer

NASA Astrophysics Data System (ADS)

Schneiders, Jan F. G.; Pröbsting, Stefan; Dwight, Richard P.; van Oudheusden, Bas W.; Scarano, Fulvio

2016-04-01

A method is proposed to determine the instantaneous pressure field from a single tomographic PIV velocity snapshot and is applied to a flat-plate turbulent boundary layer. The main concept behind the single-snapshot pressure evaluation method is to approximate the flow acceleration using the vorticity transport equation. The vorticity field calculated from the measured instantaneous velocity is advanced over a single integration time step using the vortex-in-cell (VIC) technique to update the vorticity field, after which the temporal derivative and material derivative of velocity are evaluated. The pressure in the measurement volume is subsequently evaluated by solving a Poisson equation. The procedure is validated considering data from a turbulent boundary layer experiment, obtained with time-resolved tomographic PIV at 10 kHz, where an independent surface pressure fluctuation measurement is made by a microphone. The cross-correlation coefficient of the surface pressure fluctuations calculated by the single-snapshot pressure method with respect to the microphone measurements is calculated and compared to that obtained using time-resolved pressure-from-PIV, which is regarded as benchmark. The single-snapshot procedure returns a cross-correlation comparable to the best result obtained by time-resolved PIV, which uses a nine-point time kernel. When the kernel of the time-resolved approach is reduced to three measurements, the single-snapshot method yields approximately 30 % higher correlation. Use of the method should be cautioned when the contributions to fluctuating pressure from outside the measurement volume are significant. The study illustrates the potential for simplifying the hardware configurations (e.g. high-speed PIV or dual PIV) required to determine instantaneous pressure from tomographic PIV.

Lead (Pb) isotopic fingerprinting and its applications in lead pollution studies in China: a review.

PubMed

Cheng, Hefa; Hu, Yuanan

2010-05-01

As the most widely scattered toxic metal in the world, the sources of lead (Pb) observed in contamination investigation are often difficult to identify. This review presents an overview of the principles, analysis, and applications of Pb isotopic fingerprinting in tracing the origins and transport pathways of Pb in the environment. It also summarizes the history and current status of lead pollution in China, and illustrates the power of Pb isotopic fingerprinting with examples of its recent applications in investigating the effectiveness of leaded gasoline phase-out on atmospheric lead pollution, and the sources of Pb found in various environmental media (plants, sediments, and aquatic organisms) in China. The limitations of Pb isotopic fingerprinting technique are discussed and a perspective on its development is also presented. Further methodological developments and more widespread instrument availability are expected to make isotopic fingerprinting one of the key tools in lead pollution investigation. Copyright 2009 Elsevier Ltd. All rights reserved.

Discrimination factors of carbon and nitrogen stable isotopes in meerkat feces

PubMed Central

2017-01-01

Stable isotope analysis of feces can provide a non-invasive method for tracking the dietary habits of nearly any mammalian species. While fecal samples are often collected for macroscopic and genetic study, stable isotope analysis can also be applied to expand the knowledge of species-specific dietary ecology. It is somewhat unclear how digestion changes the isotope ratios of animals’ diets, so more controlled diet studies are needed. To date, most diet-to-feces controlled stable isotope experiments have been performed on herbivores, so in this study I analyzed the carbon and nitrogen stable isotope ratios in the diet and feces of the meerkat (Suricata suricatta), a small omnivorous mammal. The carbon trophic discrimination factor between diet and feces (Δ13Cfeces) is calculated to be 0.1 ± 1.5‰, which is not significantly different from zero, and in turn, not different than the dietary input. On the other hand, the nitrogen trophic discrimination factor (Δ15Nfeces) is 1.5 ± 1.1‰, which is significantly different from zero, meaning it is different than the average dietary input. Based on data generated in this experiment and a review of the published literature, carbon isotopes of feces characterize diet, while nitrogen isotope ratios of feces are consistently higher than dietary inputs, meaning a discrimination factor needs to be taken into account. The carbon and nitrogen stable isotope values of feces are an excellent snapshot of diet that can be used in concert with other analytical methods to better understand ecology, diets, and habitat use of mammals. PMID:28626611

Dual-camera design for coded aperture snapshot spectral imaging.

PubMed

Wang, Lizhi; Xiong, Zhiwei; Gao, Dahua; Shi, Guangming; Wu, Feng

2015-02-01

Coded aperture snapshot spectral imaging (CASSI) provides an efficient mechanism for recovering 3D spectral data from a single 2D measurement. However, since the reconstruction problem is severely underdetermined, the quality of recovered spectral data is usually limited. In this paper we propose a novel dual-camera design to improve the performance of CASSI while maintaining its snapshot advantage. Specifically, a beam splitter is placed in front of the objective lens of CASSI, which allows the same scene to be simultaneously captured by a grayscale camera. This uncoded grayscale measurement, in conjunction with the coded CASSI measurement, greatly eases the reconstruction problem and yields high-quality 3D spectral data. Both simulation and experimental results demonstrate the effectiveness of the proposed method.

Application of non-traditional stable isotopes in analytical ecogeochemistry assessed by MC ICP-MS--A critical review.

PubMed

Irrgeher, Johanna; Prohaska, Thomas

2016-01-01

Analytical ecogeochemistry is an evolving scientific field dedicated to the development of analytical methods and tools and their application to ecological questions. Traditional stable isotopic systems have been widely explored and have undergone continuous development during the last century. The variations of the isotopic composition of light elements (H, O, N, C, and S) have provided the foundation of stable isotope analysis followed by the analysis of traditional geochemical isotope tracers (e.g., Pb, Sr, Nd, Hf). Questions in a considerable diversity of scientific fields have been addressed, many of which can be assigned to the field of ecogeochemistry. Over the past 15 years, other stable isotopes (e.g., Li, Zn, Cu, Cl) have emerged gradually as novel tools for the investigation of scientific topics that arise in ecosystem research and have enabled novel discoveries and explorations. These systems are often referred to as non-traditional isotopes. The small isotopic differences of interest that are increasingly being addressed for a growing number of isotopic systems represent a challenge to the analytical scientist and push the limits of today's instruments constantly. This underlines the importance of a metrologically sound concept of analytical protocols and procedures and a solid foundation of data processing strategies and uncertainty considerations before these small isotopic variations can be interpreted in the context of applied ecosystem research. This review focuses on the development of isotope research in ecogeochemistry, the requirements for successful detection of small isotopic shifts, and highlights the most recent and innovative applications in the field.

SNaPshot and StripAssay as Valuable Alternatives to Direct Sequencing for KRAS Mutation Detection in Colon Cancer Routine Diagnostics

PubMed Central

Fariña Sarasqueta, Arantza; Moerland, Elna; de Bruyne, Hanneke; de Graaf, Henk; Vrancken, Tamara; van Lijnschoten, Gesina; van den Brule, Adriaan J.C.

2011-01-01

Although direct sequencing is the gold standard for KRAS mutation detection in routine diagnostics, it remains laborious, time consuming, and not very sensitive. Our objective was to evaluate SNaPshot and the KRAS StripAssay as alternatives to sequencing for KRAS mutation detection in daily practice. KRAS exon 2–specific PCR followed by sequencing or by a SNaPshot reaction was performed. For the StripAssay, a mutant-enriched PCR was followed by hybridization to KRAS-specific probes bound to a nitrocellulose strip. To test sensitivities, dilution series of mutated DNA in wild-type DNA were made. Additionally, direct sequencing and SNaPshot were evaluated in 296 colon cancer samples. Detection limits of direct sequencing, SNaPshot, and StripAssay were 20%, 10%, and 1% tumor cells, respectively. Direct sequencing and SNaPshot can detect all 12 mutations in KRAS codons 12 and 13, whereas the StripAssay detects 10 of the most frequent ones. Workload and time to results are comparable for SNaPshot and direct sequencing. SNaPshot is flexible and easy to multiplex. The StripAssay is less time consuming for daily laboratory practice. SNaPshot is more flexible and slightly more sensitive than direct sequencing. The clinical evaluation showed comparable performances between direct sequencing and SNaPshot. The StripAssay is rapid and an extremely sensitive assay that could be considered when few tumor cells are available. However, found mutants should be confirmed to avoid risk of false positives. PMID:21354055

Application of stable isotope tools for evaluating natural and stimulated biodegradation of organic pollutants in field studies.

PubMed

Fischer, Anko; Manefield, Mike; Bombach, Petra

2016-10-01

Stable isotope tools are increasingly applied for in-depth evaluation of biodegradation of organic pollutants at contaminated field sites. They can be divided into three methods i) determination of changes in natural abundance of stable isotopes using compound-specific stable isotope analysis (CSIA), ii) detection of incorporation of stable-isotope label from a stable-isotope labelled target compound into degradation and/or mineralisation products and iii) determination of stable-isotope label incorporation into biomarkers using stable isotope probing (SIP). Stable isotope tools have been applied as key monitoring tools for multiple-line-of-evidence-approaches (MLEA) for sensitive evaluation of pollutant biodegradation. This review highlights the application of CSIA, SIP and MLEA including stable isotope tools for assessing natural and stimulated biodegradation of organic pollutants in field studies dealing with soil and groundwater contaminations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stable isotope-resolved metabolomics and applications for drug development

PubMed Central

Fan, Teresa W-M.; Lorkiewicz, Pawel; Sellers, Katherine; Moseley, Hunter N.B.; Higashi, Richard M.; Lane, Andrew N.

2012-01-01

Advances in analytical methodologies, principally nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS), during the last decade have made large-scale analysis of the human metabolome a reality. This is leading to the reawakening of the importance of metabolism in human diseases, particularly cancer. The metabolome is the functional readout of the genome, functional genome, and proteome; it is also an integral partner in molecular regulations for homeostasis. The interrogation of the metabolome, or metabolomics, is now being applied to numerous diseases, largely by metabolite profiling for biomarker discovery, but also in pharmacology and therapeutics. Recent advances in stable isotope tracer-based metabolomic approaches enable unambiguous tracking of individual atoms through compartmentalized metabolic networks directly in human subjects, which promises to decipher the complexity of the human metabolome at an unprecedented pace. This knowledge will revolutionize our understanding of complex human diseases, clinical diagnostics, as well as individualized therapeutics and drug response. In this review, we focus on the use of stable isotope tracers with metabolomics technologies for understanding metabolic network dynamics in both model systems and in clinical applications. Atom-resolved isotope tracing via the two major analytical platforms, NMR and MS, has the power to determine novel metabolic reprogramming in diseases, discover new drug targets, and facilitates ADME studies. We also illustrate new metabolic tracer-based imaging technologies, which enable direct visualization of metabolic processes in vivo. We further outline current practices and future requirements for biochemoinformatics development, which is an integral part of translating stable isotope-resolved metabolomics into clinical reality. PMID:22212615

Science from a glimpse: Hubble SNAPshot observations of massive galaxy clusters

NASA Astrophysics Data System (ADS)

Repp, A.; Ebeling, H.

2018-06-01

Hubble Space Telescope SNAPshot surveys of 86 X-ray selected galaxy clusters at 0.3 < z < 0.5 from the MACS sample have proven invaluable for the exploration of a wide range of astronomical research topics. We here present an overview of the four MACS SNAPshot surveys conducted from Cycle 14 to Cycle 20 as part of a long-term effort aimed at identifying exceptional cluster targets for in-depth follow up by the extragalactic community. We also release redshifts and X-ray luminosities of all clusters observed as part of this initiative. To illustrate the power of SNAPshot observations of MACS clusters, we explore several aspects of galaxy evolution illuminated by the images obtained for these programmes. We confirm the high lensing efficiency of X-ray selected clusters at z > 0.3. Examining the evolution of the slope of the cluster red sequence, we observe at best a slight decrease with redshift, indicating minimal age contribution since z ˜ 1. Congruent to previous studies' findings, we note that the two BCGs which are significantly bluer (≥5σ) than their clusters' red sequences reside in relaxed clusters and exhibit pronounced internal structure. Thanks to our targets' high X-ray luminosity, the subset of our sample observed with Chandra adds valuable leverage to the X-ray luminosity-optical richness relation, which, albeit with substantial scatter, is now clearly established from groups to extremely massive clusters of galaxies. We conclude that SNAPshot observations of MACS clusters stand to continue to play a vital pathfinder role for astrophysical investigations across the entire electromagnetic spectrum.

An Isotope-Powered Thermal Storage unit for space applications

NASA Technical Reports Server (NTRS)

Lisano, Michael E.; Rose, M. F.

1991-01-01

An Isotope-Powered Thermal Storage Unit (ITSU), that would store and utilize heat energy in a 'pulsed' fashion in space operations, is described. Properties of various radioisotopes are considered in conjunction with characteristics of thermal energy storage materials, to evaluate possible implementation of such a device. The utility of the unit is discussed in light of various space applications, including rocket propulsion, power generation, and spacecraft thermal management.

Snapshot spectral and polarimetric imaging; target identification with multispectral video

NASA Astrophysics Data System (ADS)

Bartlett, Brent D.; Rodriguez, Mikel D.

2013-05-01

As the number of pixels continue to grow in consumer and scientific imaging devices, it has become feasible to collect the incident light field. In this paper, an imaging device developed around light field imaging is used to collect multispectral and polarimetric imagery in a snapshot fashion. The sensor is described and a video data set is shown highlighting the advantage of snapshot spectral imaging. Several novel computer vision approaches are applied to the video cubes to perform scene characterization and target identification. It is shown how the addition of spectral and polarimetric data to the video stream allows for multi-target identification and tracking not possible with traditional RGB video collection.

CALiPER Snapshot Report: Outdoor Area Lighting - 2017

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2017-09-29

Snapshot reports use data from DOE's LED Lighting Facts product list to compare the LED performance to standard technologies, and are designed to help lighting retailers, distributors, designers, utilities, energy efficiency program sponsors, and other stakeholders understand the current state of the LED market and its trajectory.

Making sense of snapshot data: ergodic principle for clonal cell populations

PubMed Central

2017-01-01

Population growth is often ignored when quantifying gene expression levels across clonal cell populations. We develop a framework for obtaining the molecule number distributions in an exponentially growing cell population taking into account its age structure. In the presence of generation time variability, the average acquired across a population snapshot does not obey the average of a dividing cell over time, apparently contradicting ergodicity between single cells and the population. Instead, we show that the variation observed across snapshots with known cell age is captured by cell histories, a single-cell measure obtained from tracking an arbitrary cell of the population back to the ancestor from which it originated. The correspondence between cells of known age in a population with their histories represents an ergodic principle that provides a new interpretation of population snapshot data. We illustrate the principle using analytical solutions of stochastic gene expression models in cell populations with arbitrary generation time distributions. We further elucidate that the principle breaks down for biochemical reactions that are under selection, such as the expression of genes conveying antibiotic resistance, which gives rise to an experimental criterion with which to probe selection on gene expression fluctuations. PMID:29187636

Isotope separation by photochromatography

DOEpatents

Suslick, Kenneth S.

1977-01-01

An isotope separation method which comprises physically adsorbing an isotopically mixed molecular species on an adsorptive surface and irradiating the adsorbed molecules with radiation of a predetermined wavelength which will selectively excite a desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thereby separate them from the unexcited undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes.

Calcium and titanium isotopes in refractory inclusions from CM, CO, and CR chondrites

NASA Astrophysics Data System (ADS)

Kööp, Levke; Davis, Andrew M.; Krot, Alexander N.; Nagashima, Kazuhide; Simon, Steven B.

2018-05-01

Previous studies have shown that CV and CM chondrites incorporated Ca, Al-rich inclusions (CAIs) with different isotopic characteristics, which may represent different snapshots in the isotopic evolution of the early Solar System. To better understand how the isotopic characteristics of CAIs vary between different chondrite groups, we have studied calcium and titanium isotopes in CAIs from CM, CO, and CR chondrites. We show that all three chondrite groups contain CAIs with large anomalies in 48Ca and/or 50Ti (10s of ‰ or 100s of ε-units) as well as CAIs with no anomalies resolved beyond measurement uncertainties. Isotopically, the anomalous CO and CR chondrite CAIs resemble the platy hibonite crystals (PLACs) from CM chondrites, but they are more mineralogically complex. The new data are consistent with the well-established mutual exclusivity relationship between incorporation of 26Al and the presence of large anomalies in 48Ca and 50Ti. The two highly anomalous CO chondrite CAIs have correlated anomalies in 46Ti and 50Ti, while most other highly anomalous CAIs do not. This result could indicate that the reservoir with coupled 46Ti and 50Ti that was sampled by bulk meteorites and CV chondrite CAIs already existed before arrival and/or homogeneous distribution of 26Al in the protoplanetary disk. Among the studied CM chondrite CAIs are ten spinel-hibonite inclusions (SHIBs) with known oxygen isotopic compositions. Our results show that these objects sampled a reservoir that was well-mixed in oxygen, calcium, and titanium isotopes. We further show that SHIBs tend to be slightly enriched in the heavy calcium isotopes, suggesting that their formation history was different from CV chondrite CAIs.

Sulphur isotope applications in two Philippine geothermal systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bayon, F.E.B.

1996-12-31

A general and very preliminary study of sulphur isotope geochemistry is presented in this paper. Data from the Mt. Apo and Palinpinon geothermal fields are used to demonstrate the use of sulphur isotopes in geothermometry and correlation of sulphur species. Sulphur and oxygen isotope geothermometers applied to Mt. Apo data show very good agreement with temperatures estimated using other established geothermometers, as well as bore measured temperatures. This signifies that sulphur isotopes in S-species in fluids of the Mt. Apo hydrothermal system are in equilibrium at drilled depths. In Palinpinon, on the other hand, temperature estimates from fluid and mineralmore » sulphur isotope geothermometry calculations do not agree with, and are commonly higher than, well measured temperatures and temperatures estimated from other geothermometers. Sulphur isotopes in the presently-exploited Palinpinon fluid are not in equilibrium, and sulphur isotope geothermometry may be reflective of isotopic equilibrium of the deeper portions of the hydrothermal system. Dissolved sulphate in both the Palinpinon and Mt. Apo geothermal fluids appear to originate from the disproportionation of magmatic SO{sub 2} at temperatures below 400{degrees}C. Hydrogen sulphide in well discharge fluids are dominantly directly derived from the magma, with a minor amount coming from SO{sub 2} disproportionation.« less

Isotope separation by photochromatography

DOEpatents

Suslick, K.S.

1975-10-03

A photochromatographic method for isotope separation is described. An isotopically mixed molecular species is adsorbed on an adsorptive surface, and the adsorbed molecules are irradiated with radiation of a predetermined wavelength which will selectively excite desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thus separate them from the undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes. (BLM)

Single-snapshot 2D color measurement by plenoptic imaging system

NASA Astrophysics Data System (ADS)

Masuda, Kensuke; Yamanaka, Yuji; Maruyama, Go; Nagai, Sho; Hirai, Hideaki; Meng, Lingfei; Tosic, Ivana

2014-03-01

Plenoptic cameras enable capture of directional light ray information, thus allowing applications such as digital refocusing, depth estimation, or multiband imaging. One of the most common plenoptic camera architectures contains a microlens array at the conventional image plane and a sensor at the back focal plane of the microlens array. We leverage the multiband imaging (MBI) function of this camera and develop a single-snapshot, single-sensor high color fidelity camera. Our camera is based on a plenoptic system with XYZ filters inserted in the pupil plane of the main lens. To achieve high color measurement precision of this system, we perform an end-to-end optimization of the system model that includes light source information, object information, optical system information, plenoptic image processing and color estimation processing. Optimized system characteristics are exploited to build an XYZ plenoptic colorimetric camera prototype that achieves high color measurement precision. We describe an application of our colorimetric camera to color shading evaluation of display and show that it achieves color accuracy of ΔE<0.01.

Fundamental limits on dynamic inference from single-cell snapshots

PubMed Central

Weinreb, Caleb; Tusi, Betsabeh K.; Socolovsky, Merav

2018-01-01

Single-cell expression profiling reveals the molecular states of individual cells with unprecedented detail. Because these methods destroy cells in the process of analysis, they cannot measure how gene expression changes over time. However, some information on dynamics is present in the data: the continuum of molecular states in the population can reflect the trajectory of a typical cell. Many methods for extracting single-cell dynamics from population data have been proposed. However, all such attempts face a common limitation: for any measured distribution of cell states, there are multiple dynamics that could give rise to it, and by extension, multiple possibilities for underlying mechanisms of gene regulation. Here, we describe the aspects of gene expression dynamics that cannot be inferred from a static snapshot alone and identify assumptions necessary to constrain a unique solution for cell dynamics from static snapshots. We translate these constraints into a practical algorithmic approach, population balance analysis (PBA), which makes use of a method from spectral graph theory to solve a class of high-dimensional differential equations. We use simulations to show the strengths and limitations of PBA, and then apply it to single-cell profiles of hematopoietic progenitor cells (HPCs). Cell state predictions from this analysis agree with HPC fate assays reported in several papers over the past two decades. By highlighting the fundamental limits on dynamic inference faced by any method, our framework provides a rigorous basis for dynamic interpretation of a gene expression continuum and clarifies best experimental designs for trajectory reconstruction from static snapshot measurements. PMID:29463712

Taking a "Snapshot": Evaluation of a Conversation Aid for Identifying Psychosocial Needs in Young Adults with Cancer.

PubMed

Poort, Hanneke; Souza, Phoebe M; Malinowski, Paige K; MacDougall, Katelyn M; Barysauskas, Constance M; Lau Greenberg, Teresa; Tulsky, James A; Fasciano, Karen M

2018-05-21

Young adults (YAs) aged 18-35 years with cancer often experience unmet psychosocial needs. We aimed to evaluate a conversation aid ("Snapshot") that offered a framework for discussing YA-specific psychosocial concerns between patients and clinicians. We developed and implemented Snapshot between 2014 and 2016 as part of a quality improvement initiative at Dana-Farber Cancer Institute. We extracted pre- and postimplementation data from chart documentation of psychosocial concerns. YAs and social workers provided qualitative feedback on the use of Snapshot in clinical care. Postintervention chart reviews revealed a significant increase in the median number of topics documented in charts after implementation of Snapshot (preintervention median = 9 [range: 1-15] vs. postintervention median = 11 [range 6-15]; p = 0.003). Overall, YAs and social workers reported that using Snapshot improved communication and consistency of psychosocial care, with documented improvement in the following domains: understanding illness (p < 0.001), sexuality and intimacy (p = 0.03), symptom burden (p = 0.003), care planning (p < 0.001), support for caregivers and children (p = 0.02), and social, work, and home changes (p = 0.05). Snapshot improved the quality of psychosocial needs assessment among YAs with cancer. Implementation was successful in reducing variability identified in the preintervention cohort and increasing the number of YA-specific psychosocial topics discussed. A standardized conversation aid has the potential to improve quality of care for YAs by enabling early identification and intervention of psychosocial issues for all patients.

Making sense of snapshot data: ergodic principle for clonal cell populations.

PubMed

Thomas, Philipp

2017-11-01

Population growth is often ignored when quantifying gene expression levels across clonal cell populations. We develop a framework for obtaining the molecule number distributions in an exponentially growing cell population taking into account its age structure. In the presence of generation time variability, the average acquired across a population snapshot does not obey the average of a dividing cell over time, apparently contradicting ergodicity between single cells and the population. Instead, we show that the variation observed across snapshots with known cell age is captured by cell histories, a single-cell measure obtained from tracking an arbitrary cell of the population back to the ancestor from which it originated. The correspondence between cells of known age in a population with their histories represents an ergodic principle that provides a new interpretation of population snapshot data. We illustrate the principle using analytical solutions of stochastic gene expression models in cell populations with arbitrary generation time distributions. We further elucidate that the principle breaks down for biochemical reactions that are under selection, such as the expression of genes conveying antibiotic resistance, which gives rise to an experimental criterion with which to probe selection on gene expression fluctuations. © 2017 The Author(s).

Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions.

PubMed

Hussey, N E; MacNeil, M A; Olin, J A; McMeans, B C; Kinney, M J; Chapman, D D; Fisk, A T

2012-04-01

Stable-isotope analysis (SIA) can act as a powerful ecological tracer with which to examine diet, trophic position and movement, as well as more complex questions pertaining to community dynamics and feeding strategies or behaviour among aquatic organisms. With major advances in the understanding of the methodological approaches and assumptions of SIA through dedicated experimental work in the broader literature coupled with the inherent difficulty of studying typically large, highly mobile marine predators, SIA is increasingly being used to investigate the ecology of elasmobranchs (sharks, skates and rays). Here, the current state of SIA in elasmobranchs is reviewed, focusing on available tissues for analysis, methodological issues relating to the effects of lipid extraction and urea, the experimental dynamics of isotopic incorporation, diet-tissue discrimination factors, estimating trophic position, diet and mixing models and individual specialization and niche-width analyses. These areas are discussed in terms of assumptions made when applying SIA to the study of elasmobranch ecology and the requirement that investigators standardize analytical approaches. Recommendations are made for future SIA experimental work that would improve understanding of stable-isotope dynamics and advance their application in the study of sharks, skates and rays. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Low-complexity DOA estimation from short data snapshots for ULA systems using the annihilating filter technique

NASA Astrophysics Data System (ADS)

Bellili, Faouzi; Amor, Souheib Ben; Affes, Sofiène; Ghrayeb, Ali

2017-12-01

This paper addresses the problem of DOA estimation using uniform linear array (ULA) antenna configurations. We propose a new low-cost method of multiple DOA estimation from very short data snapshots. The new estimator is based on the annihilating filter (AF) technique. It is non-data-aided (NDA) and does not impinge therefore on the whole throughput of the system. The noise components are assumed temporally and spatially white across the receiving antenna elements. The transmitted signals are also temporally and spatially white across the transmitting sources. The new method is compared in performance to the Cramér-Rao lower bound (CRLB), the root-MUSIC algorithm, the deterministic maximum likelihood estimator and another Bayesian method developed precisely for the single snapshot case. Simulations show that the new estimator performs well over a wide SNR range. Prominently, the main advantage of the new AF-based method is that it succeeds in accurately estimating the DOAs from short data snapshots and even from a single snapshot outperforming by far the state-of-the-art techniques both in DOA estimation accuracy and computational cost.

APPLICATIONS OF ENVIRONMENTAL ISOTOPES FOR WATERSHED INVESTIGATIONS

EPA Science Inventory

Environmental isotopes include naturally-occurring nuclides that can be applied as tracers within watersheds (Sidle, 1998). Recent advances in mass spectroscopy may supplant many traditional and costly hydrometric techniques. It is now possible, for example, to utilize isotopes a...

Serial snapshot crystallography for materials science with SwissFEL

DOE PAGES

Dejoie, Catherine; Smeets, Stef; Baerlocher, Christian; ...

2015-04-21

New opportunities for studying (sub)microcrystalline materials with small unit cells, both organic and inorganic, will open up when the X-ray free electron laser (XFEL) presently being constructed in Switzerland (SwissFEL) comes online in 2017. Our synchrotron-based experiments mimicking the 4%-energy-bandpass mode of the SwissFEL beam show that it will be possible to record a diffraction pattern of up to 10 randomly oriented crystals in a single snapshot, to index the resulting reflections, and to extract their intensities reliably. The crystals are destroyed with each XFEL pulse, but by combining snapshots from several sets of crystals, a complete set of datamore » can be assembled, and crystal structures of materials that are difficult to analyze otherwise will become accessible. Even with a single shot, at least a partial analysis of the crystal structure will be possible, and with 10–50 femtosecond pulses, this offers tantalizing possibilities for time-resolved studies.« less

Technology for detecting spectral radiance by a snapshot multi-imaging spectroradiometer

NASA Astrophysics Data System (ADS)

Zuber, Ralf; Stührmann, Ansgar; Gugg-Helminger, Anton; Seckmeyer, Gunther

2017-12-01

Technologies to determine spectral sky radiance distributions have evolved in recent years and have enabled new applications in remote sensing, for sky radiance measurements, in biological/diagnostic applications and luminance measurements. Most classical spectral imaging radiance technologies are based on mechanical and/or spectral scans. However, these methods require scanning time in which the spectral radiance distribution might change. To overcome this limitation, different so-called snapshot spectral imaging technologies have been developed that enable spectral and spatial non-scanning measurements. We present a new setup based on a facet mirror that is already used in imaging slicing spectrometers. By duplicating the input image instead of slicing it and using a specially designed entrance slit, we are able to select nearly 200 (14 × 14) channels within the field of view (FOV) for detecting spectral radiance in different directions. In addition, a megapixel image of the FOV is captured by an additional RGB camera. This image can be mapped onto the snapshot spectral image. In this paper, the mechanical setup, technical design considerations and first measurement results of a prototype are presented. For a proof of concept, the device is radiometrically calibrated and a 10 mm × 10 mm test pattern measured within a spectral range of 380 nm-800 nm with an optical bandwidth of 10 nm (full width at half maximum or FWHM). To show its potential in the UV spectral region, zenith sky radiance measurements in the UV of a clear sky were performed. Hence, the prototype was equipped with an entrance optic with a FOV of 0.5° and modified to obtain a radiometrically calibrated spectral range of 280 nm-470 nm with a FWHM of 3 nm. The measurement results have been compared to modeled data processed by UVSPEC, which showed deviations of less than 30%. This is far from being ideal, but an acceptable result with respect to available state

SnapShot: Phosphoregulation of Mitosis.

PubMed

Burgess, Andrew; Vuong, Jenny; Rogers, Samuel; Malumbres, Marcos; O'Donoghue, Seán I

2017-06-15

During mitosis, a cell divides its duplicated genome into two identical daughter cells. This process must occur without errors to prevent proliferative diseases (e.g., cancer). A key mechanism controlling mitosis is the precise timing of more than 32,000 phosphorylation and dephosphorylation events by a network of kinases and counterbalancing phosphatases. The identity, magnitude, and temporal regulation of these events have emerged recently, largely from advances in mass spectrometry. Here, we show phosphoevents currently believed to be key regulators of mitosis. For an animated version of this SnapShot, please see http://www.cell.com/cell/enhanced/odonoghue2. Copyright © 2017. Published by Elsevier Inc.

Development of a digital-micromirror-device-based multishot snapshot spectral imaging system.

PubMed

Wu, Yuehao; Mirza, Iftekhar O; Arce, Gonzalo R; Prather, Dennis W

2011-07-15

We report on the development of a digital-micromirror-device (DMD)-based multishot snapshot spectral imaging (DMD-SSI) system as an alternative to current piezostage-based multishot coded aperture snapshot spectral imager (CASSI) systems. In this system, a DMD is used to implement compressive sensing (CS) measurement patterns for reconstructing the spatial/spectral information of an imaging scene. Based on the CS measurement results, we demonstrated the concurrent reconstruction of 24 spectral images. The DMD-SSI system is versatile in nature as it can be used to implement independent CS measurement patterns in addition to spatially shifted patterns that piezostage-based systems can offer. © 2011 Optical Society of America

SnapShot: Fanconi anemia and associated proteins.

PubMed

Wang, Anderson T; Smogorzewska, Agata

2015-01-15

Fanconi anemia is a genetic disorder resulting from biallelic mutations in one of the 17 FANC genes. It is characterized by congenital abnormalities, bone marrow failure, and cancer predisposition. The underlying cause is genomic instability resulting from the deficiency in replication-dependent DNA interstrand crosslink repair pathway commonly referred to as the Fanconi anemia-BRCA pathway. This SnapShot presents the key factors involved. Copyright © 2015 Elsevier Inc. All rights reserved.

Forensic applications of nitrogen and oxygen isotopes in tracing nitrate sources in urban environments

USGS Publications Warehouse

Silva, S.R.; Ging, P.B.; Lee, R.W.; Ebbert, J.C.; Tesoriero, A.J.; Inkpen, E.L.

2002-01-01

Ground and surface waters in urban areas are susceptible to nitrate contamination from septic systems, leaking sewer lines, and fertilizer applications. Source identification is a primary step toward a successful remediation plan in affected areas. In this respect, nitrogen and oxygen isotope ratios of nitrate, in conjunction with hydrologic data and water chemistry, have proven valuable in urban studies from Austin, Texas, and Tacoma, Washington. In Austin, stream water was sampled during stremflow and baseflow conditions to assess surface and subsurface sources of nitrate, respectively. In Tacoma, well waters were sampled in adjacent sewered and un-sewered areas to determine if locally high nitrate concentrations were caused by septic systems in the un-sewered areas. In both studies, sewage was identified as a nitrate source and mixing between sewage and other sources of nitrate was apparent. In addition to source identification, combined nitrogen and oxygen isotopes were important in determining the significance of denitrification, which can complicate source assessment by reducing nitrate concentrations and increasing ??15N values. The two studies illustrate the value of nitrogen and oxygen isotopes of nitrate for forensic applications in urban areas. ?? Published by Elsevier Science Ltd. on behalf of AEHS.

Snapshot Imaging Spectrometry in the Visible and Long Wave Infrared

NASA Astrophysics Data System (ADS)

Maione, Bryan David

Imaging spectrometry is an optical technique in which the spectral content of an object is measured at each location in space. The main advantage of this modality is that it enables characterization beyond what is possible with a conventional camera, since spectral information is generally related to the chemical composition of the object. Due to this, imaging spectrometers are often capable of detecting targets that are either morphologically inconsistent, or even under resolved. A specific class of imaging spectrometer, known as a snapshot system, seeks to measure all spatial and spectral information simultaneously, thereby rectifying artifacts associated with scanning designs, and enabling the measurement of temporally dynamic scenes. Snapshot designs are the focus of this dissertation. Three designs for snapshot imaging spectrometers are developed, each providing novel contributions to the field of imaging spectrometry. In chapter 2, the first spatially heterodyned snapshot imaging spectrometer is modeled and experimentally validated. Spatial heterodyning is a technique commonly implemented in non-imaging Fourier transform spectrometry. For Fourier transform imaging spectrometers, spatial heterodyning improves the spectral resolution trade space. Additionally, in this chapter a unique neural network based spectral calibration is developed and determined to be an improvement beyond Fourier and linear operator based techniques. Leveraging spatial heterodyning as developed in chapter 2, in chapter 3, a high spectral resolution snapshot Fourier transform imaging spectrometer, based on a Savart plate interferometer, is developed and experimentally validated. The sensor presented in this chapter is the highest spectral resolution sensor in its class. High spectral resolution enables the sensor to discriminate narrowly spaced spectral lines. The capabilities of neural networks in imaging spectrometry are further explored in this chapter. Neural networks are used to

SnapShot: Hormones of the gastrointestinal tract.

PubMed

Coate, Katie C; Kliewer, Steven A; Mangelsdorf, David J

2014-12-04

Specialized endocrine cells secrete a variety of peptide hormones all along the gastrointestinal (GI) tract, making it one of the largest endocrine organs in the body. Nutrients and developmental and neural cues trigger the secretion of gastrointestinal (GI) hormones from specialized endocrine cells along the GI tract. These hormones act in target tissues to facilitate digestion and regulate energy homeostasis. This SnapShot summarizes the production and functions of GI hormones. Copyright © 2014 Elsevier Inc. All rights reserved.

A Snapshot of Organizational Climate: Perceptions of Extension Faculty

ERIC Educational Resources Information Center

Tower, Leslie E.; Bowen, Elaine; Alkadry, Mohamad G.

2011-01-01

This article provides a snapshot of the perceptions of workplace climate of Extension faculty at a land-grant, research-high activity university, compared with the perceptions of non-Extension faculty at the same university. An online survey was conducted with a validated instrument. The response rate for university faculty was 44% (968); the…

Natural Isotope Abundance in Metabolites: Techniques and Kinetic Isotope Effect Measurement in Plant, Animal, and Human Tissues.

PubMed

Tea, Illa; Tcherkez, Guillaume

2017-01-01

The natural isotope abundance in bulk organic matter or tissues is not a sufficient base to investigate physiological properties, biosynthetic mechanisms, and nutrition sources of biological systems. In fact, isotope effects in metabolism lead to a heterogeneous distribution of 2 H, 18 O, 13 C, and 15 N isotopes in metabolites. Therefore, compound-specific isotopic analysis (CSIA) is crucial to biological and medical applications of stable isotopes. Here, we review methods to implement CSIA for 15 N and 13 C from plant, animal, and human samples and discuss technical solutions that have been used for the conversion to CO 2 and N 2 for IRMS analysis, derivatization and isotope effect measurements. It appears that despite the flexibility of instruments used for CSIA, there is no universal method simply because the chemical nature of metabolites of interest varies considerably. Also, CSIA methods are often limited by isotope effects in sample preparation or the addition of atoms from the derivatizing reagents, and this implies that corrections must be made to calculate a proper δ-value. Therefore, CSIA has an enormous potential for biomedical applications, but its utilization requires precautions for its successful application. © 2017 Elsevier Inc. All rights reserved.

Overview Snapshot Observational Technique (OSOT): Administration Manual Experimental Research Form.

ERIC Educational Resources Information Center

Coller, Alan R.

Overview Snapshot Observational Technical (OSOT) is specifically designed to allow users to obtain both pictorial and categorical data related to the transactions in context component of early childhood (prekindergarten and kindergarten) educational programs. Such information is especially useful in operations calling for descriptive evaluation.…

EnviroAtlas - NHDPlus V2 WBD Snapshot, EnviroAtlas version - Conterminous United States

EPA Pesticide Factsheets

This EnviroAtlas dataset is a digital hydrologic unit boundary layer to the Subwatershed (12-digit) 6th level for the conterminous United States, based on the January 6, 2015 NHDPlus V2 WBD (Watershed Boundary Dataset) Snapshot (NHDPlusV21_NationalData_WBDSnapshot_FileGDB_05). The feature class has been edited for use in for EPA ORD's EnviroAtlas. Features in Canada and Mexico have been removed, the boundaries of three 12-digit HUCs have been edited to eliminate gaps and overlaps, the dataset has been dissolved on HUC_12 to create multipart polygons, and information on the percent land area has been added. Hawaii, Puerto Rico, and the U.S. Virgin Islands have been removed, and can be downloaded separately. Other than these modifications, the dataset is the same as the WBD Snapshot included in NHDPlus V2.This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

Photochemical isotope separation

DOEpatents

Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

1987-01-01

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Laser isotope separation

DOEpatents

Robinson, C.P.; Reed, J.J.; Cotter, T.P.; Boyer, K.; Greiner, N.R.

1975-11-26

A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light is described. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

Laser isotope separation

DOEpatents

Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Boyer, Keith; Greiner, Norman R.

1988-01-01

A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

Photochemical isotope separation

DOEpatents

Robinson, C.P.; Jensen, R.J.; Cotter, T.P.; Greiner, N.R.; Boyer, K.

1987-04-28

A process is described for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium. 8 figs.

web-based interactive data processing: application to stable isotope metrology.

PubMed

Verkouteren, R M; Lee, J N

2001-08-01

To address a fundamental need in stable isotope metrology, the National Institute of Standards and Technology (NIST) has established a web-based interactive data-processing system accessible through a common gateway interface (CGI) program on the internet site http://www. nist.gov/widps-co2. This is the first application of a web-based tool that improves the measurement traceability afforded by a series of NIST standard materials. Specifically, this tool promotes the proper usage of isotope reference materials (RMs) and improves the quality of reported data from extensive measurement networks. Through the International Atomic Energy Agency (IAEA), we have defined standard procedures for stable isotope measurement and data-processing, and have determined and applied consistent reference values for selected NIST and IAEA isotope RMs. Measurement data of samples and RMs are entered into specified fields on the web-based form. These data are submitted through the CGI program on a NIST Web server, where appropriate calculations are performed and results returned to the client. Several international laboratories have independently verified the accuracy of the procedures and algorithm for measurements of naturally occurring carbon-13 and oxygen-18 abundances and slightly enriched compositions up to approximately 150% relative to natural abundances. To conserve the use of the NIST RMs, users may determine value assignments for a secondary standard to be used in routine analysis. Users may also wish to validate proprietary algorithms embedded in their laboratory instrumentation, or specify the values of fundamental variables that are usually fixed in reduction algorithms to see the effect on the calculations. The results returned from the web-based tool are limited in quality only by the measurements themselves, and further value may be realized through the normalization function. When combined with stringent measurement protocols, two- to threefold improvements have been

Energy Transition Initiative, Island Energy Snapshot - British Virgin Islands (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2015-03-01

This profile provides a snapshot of the energy landscape of the British Virgin Islands (BVI), one of three sets of the Virgin Island territories in an archipelago making up the northern portion of the Lesser Antilles.

Population-Level Metrics of Trophic Structure Based on Stable Isotopes and Their Application to Invasion Ecology

PubMed Central

Jackson, Michelle C.; Donohue, Ian; Jackson, Andrew L.; Britton, J. Robert; Harper, David M.; Grey, Jonathan

2012-01-01

Biological invasions are a significant driver of human-induced global change and many ecosystems sustain sympatric invaders. Interactions occurring among these invaders have important implications for ecosystem structure and functioning, yet they are poorly understood. Here we apply newly developed metrics derived from stable isotope data to provide quantitative measures of trophic diversity within populations or species. We then use these to test the hypothesis that sympatric invaders belonging to the same functional feeding group occupy a smaller isotopic niche than their allopatric counterparts. Two introduced, globally important, benthic omnivores, Louisiana swamp crayfish (Procambarus clarkii) and carp (Cyprinus carpio), are sympatric in Lake Naivasha, Kenya. We applied our metrics to an 8-year data set encompassing the establishment of carp in the lake. We found a strong asymmetric interaction between the two invasive populations, as indicated by inverse correlations between carp abundance and measures of crayfish trophic diversity. Lack of isotopic niche overlap between carp and crayfish in the majority of years indicated a predominantly indirect interaction. We suggest that carp-induced habitat alteration reduced the diversity of crayfish prey, resulting in a reduction in the dietary niche of crayfish. Stable isotopes provide an integrated signal of diet over space and time, offering an appropriate scale for the study of population niches, but few isotope studies have retained the often insightful information revealed by variability among individuals in isotope values. Our population metrics incorporate such variation, are robust to the vagaries of sample size and are a useful additional tool to reveal subtle dietary interactions among species. Although we have demonstrated their applicability specifically using a detailed temporal dataset of species invasion in a lake, they have a wide array of potential ecological applications. PMID:22363724

Population-level metrics of trophic structure based on stable isotopes and their application to invasion ecology.

PubMed

Jackson, Michelle C; Donohue, Ian; Jackson, Andrew L; Britton, J Robert; Harper, David M; Grey, Jonathan

2012-01-01

Biological invasions are a significant driver of human-induced global change and many ecosystems sustain sympatric invaders. Interactions occurring among these invaders have important implications for ecosystem structure and functioning, yet they are poorly understood. Here we apply newly developed metrics derived from stable isotope data to provide quantitative measures of trophic diversity within populations or species. We then use these to test the hypothesis that sympatric invaders belonging to the same functional feeding group occupy a smaller isotopic niche than their allopatric counterparts. Two introduced, globally important, benthic omnivores, Louisiana swamp crayfish (Procambarus clarkii) and carp (Cyprinus carpio), are sympatric in Lake Naivasha, Kenya. We applied our metrics to an 8-year data set encompassing the establishment of carp in the lake. We found a strong asymmetric interaction between the two invasive populations, as indicated by inverse correlations between carp abundance and measures of crayfish trophic diversity. Lack of isotopic niche overlap between carp and crayfish in the majority of years indicated a predominantly indirect interaction. We suggest that carp-induced habitat alteration reduced the diversity of crayfish prey, resulting in a reduction in the dietary niche of crayfish. Stable isotopes provide an integrated signal of diet over space and time, offering an appropriate scale for the study of population niches, but few isotope studies have retained the often insightful information revealed by variability among individuals in isotope values. Our population metrics incorporate such variation, are robust to the vagaries of sample size and are a useful additional tool to reveal subtle dietary interactions among species. Although we have demonstrated their applicability specifically using a detailed temporal dataset of species invasion in a lake, they have a wide array of potential ecological applications.

Isotope pattern deconvolution as rising tool for isotope tracer studies in environmental research

NASA Astrophysics Data System (ADS)

Irrgeher, Johanna; Zitek, Andreas; Prohaska, Thomas

2014-05-01

During the last decade stable isotope tracers have emerged as versatile tool in ecological research. Besides 'intrinsic' isotope tracers caused by the natural variation of isotopes, the intentional introduction of 'extrinsic' enriched stable isotope tracers into biological systems has gained significant interest. Hereby the induced change in the natural isotopic composition of an element allows amongst others for studying the fate and fluxes of metals, trace elements and species in organisms or provides an intrinsic marker or tag of particular biological samples. Due to the shoreless potential of this methodology, the number of publications dealing with applications of isotope (double) spikes as tracers to address research questions in 'real world systems' is constantly increasing. However, some isotope systems like the natural Sr isotopic system, although potentially very powerful for this type of application, are still rarely used, mainly because their adequate measurement/determination poses major analytical challenges; as e.g. Sr is available in significant amounts in natural samples. In addition, biological systems underlie complex processes such as metabolism, adsorption/desorption or oxidation/reduction. As a consequence, classic evaluation approaches such as the isotope dilution mass spectrometry equation are often not applicable because of the unknown amount of tracer finally present in the sample. Isotope pattern deconvolution (IPD), based on multiple linear regression, serves as simplified alternative data processing strategy to double spike isotope dilution calculations. The outstanding advantage of this mathematical tool lies in the possibility of deconvolving the isotope pattern in a spiked sample without knowing the quantities of enriched isotope tracer being incorporated into the natural sample matrix as well as the degree of impurities and species-interconversion (e.g. from sample preparation). Here, the potential of IPD for environmental tracer

SnapShot: Visualization to Propel Ice Hockey Analytics.

PubMed

Pileggi, H; Stolper, C D; Boyle, J M; Stasko, J T

2012-12-01

Sports analysts live in a world of dynamic games flattened into tables of numbers, divorced from the rinks, pitches, and courts where they were generated. Currently, these professional analysts use R, Stata, SAS, and other statistical software packages for uncovering insights from game data. Quantitative sports consultants seek a competitive advantage both for their clients and for themselves as analytics becomes increasingly valued by teams, clubs, and squads. In order for the information visualization community to support the members of this blossoming industry, it must recognize where and how visualization can enhance the existing analytical workflow. In this paper, we identify three primary stages of today's sports analyst's routine where visualization can be beneficially integrated: 1) exploring a dataspace; 2) sharing hypotheses with internal colleagues; and 3) communicating findings to stakeholders.Working closely with professional ice hockey analysts, we designed and built SnapShot, a system to integrate visualization into the hockey intelligence gathering process. SnapShot employs a variety of information visualization techniques to display shot data, yet given the importance of a specific hockey statistic, shot length, we introduce a technique, the radial heat map. Through a user study, we received encouraging feedback from several professional analysts, both independent consultants and professional team personnel.

78 FR 63501 - Request To Submit a Two-Part Application-Northwest Medical Isotopes, LLC

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-24

... NUCLEAR REGULATORY COMMISSION [Project No. 0803; NRC-2013-0235] Request To Submit a Two-Part Application--Northwest Medical Isotopes, LLC AGENCY: Nuclear Regulatory Commission. ACTION: Exemption. SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing an exemption in response to an August 9, 2013...

A Snapshot-Based Mechanism for Celestial Orientation.

PubMed

El Jundi, Basil; Foster, James J; Khaldy, Lana; Byrne, Marcus J; Dacke, Marie; Baird, Emily

2016-06-06

In order to protect their food from competitors, ball-rolling dung beetles detach a piece of dung from a pile, shape it into a ball, and roll it away along a straight path [1]. They appear to rely exclusively on celestial compass cues to maintain their bearing [2-8], but the mechanism that enables them to use these cues for orientation remains unknown. Here, we describe the orientation strategy that allows dung beetles to use celestial cues in a dynamic fashion. We tested the underlying orientation mechanism by presenting beetles with a combination of simulated celestial cues (sun, polarized light, and spectral cues). We show that these animals do not rely on an innate prediction of the natural geographical relationship between celestial cues, as other navigating insects seem to [9, 10]. Instead, they appear to form an internal representation of the prevailing celestial scene, a "celestial snapshot," even if that scene represents a physical impossibility for the real sky. We also find that the beetles are able to maintain their bearing with respect to the presented cues only if the cues are visible when the snapshot is taken. This happens during the "dance," a behavior in which the beetle climbs on top of its ball and rotates about its vertical axis [11]. This strategy for reading celestial signals is a simple but efficient mechanism for straight-line orientation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Full-Spectrum-Analysis Isotope ID

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, Dean J.; Harding, Lee; Thoreson, Gregory G.

2017-06-28

FSAIsotopeID analyzes gamma ray spectra to identify radioactive isotopes (radionuclides). The algorithm fits the entire spectrum with combinations of pre-computed templates for a comprehensive set of radionuclides with varying thicknesses and compositions of shielding materials. The isotope identification algorithm is suitable for the analysis of spectra collected by gamma-ray sensors ranging from medium-resolution detectors, such a NaI, to high-resolution detectors, such as HPGe. In addition to analyzing static measurements, the isotope identification algorithm is applied for the radiation search applications. The search subroutine maintains a running background spectrum that is passed to the isotope identification algorithm, and it also selectsmore » temporal integration periods that optimize the responsiveness and sensitivity. Gain stabilization is supported for both types of applications.« less

High Precision Isotope Analyses Using Multi-Collector SIMS: Applications to Earth and Planetary Science.

NASA Astrophysics Data System (ADS)

Kita, N. T.; Ushikubo, T.; Valley, J. W.

2008-05-01

The CAMECA IMS-1280 large radius, multicollector ion microprobe at the Wisc-SIMS National Facility is capable of high accuracy and precision for in situ analysis of isotope ratios. With improved hardware stability and software capability, high precision isotope analyses are routinely performed, typically 5 min per spot. We have developed analytical protocols for stable isotope analyses of oxygen, carbon, Mg, Si and Sulfur using multi-collector Faraday Cups (MCFC) and achieved precision of 0.1-0.2 ‰ (1SD) from a typically 10μm spot analyses. A number of isotopically homogeneous mineral standards have been prepared and calibrated in order to certify the accuracy of analyses in the same level. When spatial resolution is critical, spot size is reduced down to sub- μm for δ 18O to obtain better than 0.5‰ (1SD) precision by using electron multiplier (EM) on multi-collection system. Multi-collection EM analysis is also applied at 10 ppm level to Li isotope ratios in zircon with precision better than 2‰ (1SD). A few applications will be presented. (1) Oxygen three isotope analyses of chondrules in ordinary chondrites revealed both mass dependent and mass independent oxygen isotope fractionations among chondrules as well as within individual chondrules. The results give constraints on the process of chondrule formation and origin of isotope reservoirs in the early solar system. (2) High precision 26Al-26Mg (half life of 0.73 Ma) chronology is applied to zoned melilite and anorthite from Ca, Al-rich inclusions (CAI) in Leoville meteorite, and a well-defined internal isochron is obtained. The results indicate the Al- Mg system was remained closed within 40ky of the crystallization of melilite and anorthite in this CAI. (3) Sub- μm spot analyses of δ18O in isotopically zoned zircon from high-grade metamorphism reveals a diffusion profile of ~6‰ over 2μm, indicating slow diffusion of oxygen in zircon. This result also implies that old Archean detrital zircons (> 4

Connecting Kids to Technology: Challenges and Opportunities. KIDS COUNT Snapshot.

ERIC Educational Resources Information Center

Wilhelm, Tony; Carmen, Delia; Reynolds, Megan

The 2000 KIDS COUNT Data Book examined the isolation that plagues many low-income families. The lack of home Internet access will only deepen the isolation as opportunities and meaningful connections to support services become primarily available online. This snapshot examines the demographics of the digital divide between those who have and those…

Sulfur isotopic evidence for sources of volatiles in Siberian Traps magmas

NASA Astrophysics Data System (ADS)

Black, Benjamin A.; Hauri, Erik H.; Elkins-Tanton, Linda T.; Brown, Stephanie M.

2014-05-01

The Siberian Traps flood basalts transferred a large mass of volatiles from the Earth's mantle and crust to the atmosphere. The eruption of the large igneous province temporally overlapped with the end-Permian mass extinction. Constraints on the sources of Siberian Traps volatiles are critical for determining the overall volatile budget, the role of crustal assimilation, the genesis of Noril'sk ore deposits, and the environmental effects of magmatism. We measure sulfur isotopic ratios ranging from -10.8‰ to +25.3‰ Vienna Cañon Diablo Troilite (V-CDT) in melt inclusions from Siberian Traps basaltic rocks. Our measurements, which offer a snapshot of sulfur cycling far from mid-ocean ridge and arc settings, suggest the δ34S of the Siberian Traps mantle melt source was close to that of mid-ocean ridge basalts. In conjunction with previously published whole rock measurements from Noril'sk, our sulfur isotopic data indicate that crustal contamination was widespread and heterogeneous—though not universal—during the emplacement of the Siberian Traps. Incorporation of crustal materials likely increased the total volatile budget of the large igneous province, thereby contributing to Permian-Triassic environmental deterioration.

ALL-UNION CONFERENCE ON APPLICATIONS OF RADIOACTIVE ISOTOPES AND NUCLEAR EMISSIONS IN THE NATIONAL INDUSTRY OF USSR (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1960-09-01

Papers presented at the All-Union Conference on Industrial Applications of Radioactive Isotopes and Nuclear Emissions in the National Economy of USSR, April 12 to 16, 1960, in Riga are surveyed. Short summaries are given on applications of radioactive isotopes and nuclear emissions in prospecting, developing mineral resources, metallurgy, ore enrichment processes, machine construction technology, agriculture, food processing, and medicine. Sources of alpha , beta , and gamma radiation for control and automation of processes are also discussed. The full reports from the conference will be published in 1960. (R.V.J.)

U.S. Department of Energy Isotope Program

ScienceCinema

None

2018-01-16

The National Isotope Development Center (NIDC) interfaces with the User Community and manages the coordination of isotope production across the facilities and business operations involved in the production, sale, and distribution of isotopes. A virtual center, the NIDC is funded by the Isotope Development and Production for Research and Applications (IDPRA) subprogram of the Office of Nuclear Physics in the U.S. Department of Energy Office of Science. PNNL’s Isotope Program operates in a multi-program category-2 nuclear facility, the Radiochemical Processing Laboratory (RPL), that contains 16 hot cells and 20 gloveboxes. As part of the DOE Isotope Program, the Pacific Northwest National Laboratory dispenses strontium-90, neptunium-237, radium-223, and thorium-227. PNNL’s Isotope Program uses a dedicated hot-cell for strontium-90 dispensing and a dedicated glovebox for radium-223 and thorium-227 dispensing. PNNL’s Isotope Program has access to state of the art analytical equipment in the RPL to support their research and production activities. DOE Isotope Program funded research at PNNL has advanced the application of automated radiochemistry for isotope such as zirconium-89 and astatine-211 in partnership with the University of Washington.

U.S. Department of Energy Isotope Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

The National Isotope Development Center (NIDC) interfaces with the User Community and manages the coordination of isotope production across the facilities and business operations involved in the production, sale, and distribution of isotopes. A virtual center, the NIDC is funded by the Isotope Development and Production for Research and Applications (IDPRA) subprogram of the Office of Nuclear Physics in the U.S. Department of Energy Office of Science. PNNL’s Isotope Program operates in a multi-program category-2 nuclear facility, the Radiochemical Processing Laboratory (RPL), that contains 16 hot cells and 20 gloveboxes. As part of the DOE Isotope Program, the Pacific Northwestmore » National Laboratory dispenses strontium-90, neptunium-237, radium-223, and thorium-227. PNNL’s Isotope Program uses a dedicated hot-cell for strontium-90 dispensing and a dedicated glovebox for radium-223 and thorium-227 dispensing. PNNL’s Isotope Program has access to state of the art analytical equipment in the RPL to support their research and production activities. DOE Isotope Program funded research at PNNL has advanced the application of automated radiochemistry for isotope such as zirconium-89 and astatine-211 in partnership with the University of Washington.« less

Calculation and mitigation of isotopic interferences in liquid chromatography-mass spectrometry/mass spectrometry assays and its application in supporting microdose absolute bioavailability studies.

PubMed

Gu, Huidong; Wang, Jian; Aubry, Anne-Françoise; Jiang, Hao; Zeng, Jianing; Easter, John; Wang, Jun-sheng; Dockens, Randy; Bifano, Marc; Burrell, Richard; Arnold, Mark E

2012-06-05

A methodology for the accurate calculation and mitigation of isotopic interferences in liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) assays and its application in supporting microdose absolute bioavailability studies are reported for the first time. For simplicity, this calculation methodology and the strategy to minimize the isotopic interference are demonstrated using a simple molecule entity, then applied to actual development drugs. The exact isotopic interferences calculated with this methodology were often much less than the traditionally used, overestimated isotopic interferences simply based on the molecular isotope abundance. One application of the methodology is the selection of a stable isotopically labeled internal standard (SIL-IS) for an LC-MS/MS bioanalytical assay. The second application is the selection of an SIL analogue for use in intravenous (i.v.) microdosing for the determination of absolute bioavailability. In the case of microdosing, the traditional approach of calculating isotopic interferences can result in selecting a labeling scheme that overlabels the i.v.-dosed drug or leads to incorrect conclusions on the feasibility of using an SIL drug and analysis by LC-MS/MS. The methodology presented here can guide the synthesis by accurately calculating the isotopic interferences when labeling at different positions, using different selective reaction monitoring (SRM) transitions or adding more labeling positions. This methodology has been successfully applied to the selection of the labeled i.v.-dosed drugs for use in two microdose absolute bioavailability studies, before initiating the chemical synthesis. With this methodology, significant time and cost saving can be achieved in supporting microdose absolute bioavailability studies with stable labeled drugs.

A Mass Spectrometry Study of Isotope Separation in the Laser Plume

NASA Astrophysics Data System (ADS)

Suen, Timothy Wu

Accurate quantification of isotope ratios is critical for both preventing the development of illicit weapons programs in nuclear safeguards and identifying the source of smuggled material in nuclear forensics. While isotope analysis has traditionally been performed by mass spectrometry, the need for in situ measurements has prompted the development of optical techniques, such as laser-induced breakdown spectroscopy (LIBS) and laser ablation molecular isotopic spectrometry (LAMIS). These optical measurements rely on laser ablation for direct solid sampling, but several past studies have suggested that the distribution of isotopes in the ablation plume is not uniform. This study seeks to characterize isotope separation in the laser plume through the use of orthogonal-acceleration time-of-flight mass spectrometry. A silver foil was ablated with a Nd:YAG at 355 nm at an energy of 50 muJ with a spot size of 71 mum, for a fluence of 1.3 J/cm2 and an irradiance of 250 MW/cm2. Flat-plate repellers were used to sample the plume, and a temporal profile of the ions was obtained by varying the time delay on the high-voltage pulse. A spatial profile along the axis of the plume was generated by changing the position of the sample, which yielded snapshots of the isotopic composition with time. In addition, the reflectron time-of-flight system was used as an energy filter in conjunction with the repellers to sample slices of the laser plasma orthogonal to the plume axis. Mass spectrometry of the plume revealed a fast ion distribution and a slow ion distribution. Measurements taken across the entire plume showed the fast 109Ag ions slightly ahead in both space and time, causing the 107Ag fraction to drop to 0.34 at 3 mus, 4 mm from the sample surface. Although measurements centered on the near side of the plume did not show isotope separation, the slow ions on the far side of the plume included much more 109Ag than 107Ag. In addition to examining the isotope content of the ablation

Abstracts of the 24th international isotope society (UK group) symposium: synthesis and applications of labelled compounds 2015.

PubMed

Aigbirhio, F I; Allwein, S; Anwar, A; Atzrodt, J; Audisio, D; Badman, G; Bakale, R; Berthon, F; Bragg, R; Brindle, K M; Bushby, N; Campos, S; Cant, A A; Chan, M Y T; Colbon, P; Cornelissen, B; Czarny, B; Derdau, V; Dive, V; Dunscombe, M; Eggleston, I; Ellis-Sawyer, K; Elmore, C S; Engstrom, P; Ericsson, C; Fairlamb, I J S; Georgin, D; Godfrey, S P; He, L; Hickey, M J; Huscroft, I T; Kerr, W J; Lashford, A; Lenz, E; Lewinton, S; L'Hermite, M M; Lindelöf, Å; Little, G; Lockley, W J S; Loreau, O; Maddocks, S; Marguerit, M; Mirabello, V; Mudd, R J; Nilsson, G N; Owens, P K; Pascu, S I; Patriarche, G; Pimlott, S L; Pinault, M; Plastow, G; Racys, D T; Reif, J; Rossi, J; Ruan, J; Sarpaki, S; Sephton, S M; Simonsson, R; Speed, D J; Sumal, K; Sutherland, A; Taran, F; Thuleau, A; Wang, Y; Waring, M; Watters, W H; Wu, J; Xiao, J

2016-04-01

The 24th annual symposium of the International Isotope Society's United Kingdom Group took place at the Møller Centre, Churchill College, Cambridge, UK on Friday 6th November 2015. The meeting was attended by 77 delegates from academia and industry, the life sciences, chemical, radiochemical and scientific instrument suppliers. Delegates were welcomed by Dr Ken Lawrie (GlaxoSmithKline, UK, chair of the IIS UK group). The subsequent scientific programme consisted of oral presentations, short 'flash' presentations in association with particular posters and poster presentations. The scientific areas covered included isotopic synthesis, regulatory issues, applications of labelled compounds in imaging, isotopic separation and novel chemistry with potential implications for isotopic synthesis. Both short-lived and long-lived isotopes were represented, as were stable isotopes. The symposium was divided into a morning session chaired by Dr Rebekka Hueting (University of Oxford, UK) and afternoon sessions chaired by Dr Sofia Pascu (University of Bath, UK) and by Dr Alan Dowling (Syngenta, UK). The UK meeting concluded with remarks from Dr Ken Lawrie (GlaxoSmithKline, UK). Copyright © 2016 John Wiley & Sons, Ltd.

Snapshot imaging Fraunhofer line discriminator for detection of plant fluorescence

NASA Astrophysics Data System (ADS)

Gupta Roy, S.; Kudenov, M. W.

2015-05-01

Non-invasive quantification of plant health is traditionally accomplished using reflectance based metrics, such as the normalized difference vegetative index (NDVI). However, measuring plant fluorescence (both active and passive) to determine photochemistry of plants has gained importance. Due to better cost efficiency, lower power requirements, and simpler scanning synchronization, detecting passive fluorescence is preferred over active fluorescence. In this paper, we propose a high speed imaging approach for measuring passive plant fluorescence, within the hydrogen alpha Fraunhofer line at ~656 nm, using a Snapshot Imaging Fraunhofer Line Discriminator (SIFOLD). For the first time, the advantage of snapshot imaging for high throughput Fraunhofer Line Discrimination (FLD) is cultivated by our system, which is based on a multiple-image Fourier transform spectrometer and a spatial heterodyne interferometer (SHI). The SHI is a Sagnac interferometer, which is dispersion compensated using blazed diffraction gratings. We present data and techniques for calibrating the SIFOLD to any particular wavelength. This technique can be applied to quantify plant fluorescence at low cost and reduced complexity of data collection.

Sr - an element shows the way - Applications of Sr isotopes for provenance, tracing and migration (Invited)

NASA Astrophysics Data System (ADS)

Prohaska, T.; Irrgeher, J.; Zitek, A.; Teschler Nicola, M.

2010-12-01

Strontium - named after the small Scottish town Strontian - as such is an element with little popularity. Firstly described by Martin Heinrich Klaproth in 1798, the metal is used in metallurgy to some extent whereas its compounds are interesting in glass industries, electronics and pyrotechnics. The element has chemical similarity to Ca and makes up 1/60 of the earth’s amount of the latter. Nonetheless, it is its isotopic composition which makes Sr so interesting for a large number of scientists. The natural composition of the four naturally occurring isotopes (84Sr, 86Sr 87Sr and 88Sr) varies in nature due to the radioactive decay of 87Rb to 87Sr. Thus, it was early recognized as geochronometer especially in Ca rich matrices. With increasing precision of applied methodology, the natural variation of the 87Sr/86Sr isotope ratio (analyzed at first mainly by thermal ionization mass spectrometry (TIMS)) became more and more popular in provenance studies. The natural variation of the ratio is mainly determined by the geological age and the original composition of the rock and can be used therefore as fingerprint of the local geology. The ratio is transferred with no significant fractionation via the water into plants and finally via the food chain into animal and human tissues (especially bones and teeth). As the element is chemically similar to Ca, it appears in most matrices. The use for provenance studies is supported by the fact that the long half life (4.8 x 1010 years) does not lead to an alteration during the time scales which are investigated (from recent samples to human or animal skeletal remains which date back up to 30.000 BC). The uniqueness of the system besides the natural variation is defined by the ubiquity in nature and the relatively high (and thus measurable) elemental concentration in most tissues. It was finally the advent of multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) which augmented the number of applications

"Application of Tunable Diode Laser Spectrometry to Isotopic Studies for Exobiology"

NASA Technical Reports Server (NTRS)

Sauke, Todd B.

1999-01-01

Computer-controlled electrically-activated valves for rapid gas-handling have been incorporated into the Stable Isotope Laser Spectrometer (SILS) which now permits rapid filling and evacuating of the sample and reference gas cells, Experimental protocols have been developed to take advantage of the fast gas handling capabilities of the instrument and to achieve increased accuracy which results from reduced instrumental drift during rapid isotopic ratio measurements. Using these protocols' accuracies of 0.5 del (0.05%) have been achieved in measurements of 13C/12C in carbon dioxide. Using the small stable isotope laser spectrometer developed in a related PIDDP project of the Co-I, protocols for acquisition of rapid sequential calibration spectra were developed which resulted in 0.5 del accuracy also being achieved in this less complex instrument. An initial version of software for automatic characterization of tunable diode lasers has been developed and diodes have been characterized in order to establish their spectral output properties. A new state-of-the-art high operating temperature (200 K) mid infrared diode laser was purchased (through NASA procurement) and characterized. A thermo-electrically cooled mid infrared tunable diode laser system for use with high temperature operation lasers was developed. In addition to isotopic ratio measurements of carbon and oxygen, measurements of a third biologically important element (15N/14N in N2O gas) have been achieved to a preliminary accuracy of about 0.2%. Transfer of the basic SILS technology to the commercial sector is proceeding under an unfunded Space Act Agreement between NASA and SpiraMed, a medical diagnostic instrument company. Two patents have been issued. Foreign patents based on these two US patents have been applied for and are expected to be issued. A preliminary design was developed for a thermo-electrically cooled SILS instruments for application to planetary space flight exploration missions.

ENVIRONMENTAL ISOTOPES FOR RESOLUTION OF HYDROLOGY PROBLEMS

EPA Science Inventory

The use of environmental isotopes as tracers in the hydrosphere is increasing as analytical instrumentation improves and more applications are discovered. There exists still misconceptions on the role of isotopes in resolving hydrology problems. Naturally occurring isotopes in th...

Model reduction of dynamical systems by proper orthogonal decomposition: Error bounds and comparison of methods using snapshots from the solution and the time derivatives [Proper orthogonal decomposition model reduction of dynamical systems: error bounds and comparison of methods using snapshots from the solution and the time derivatives

DOE PAGES

Kostova-Vassilevska, Tanya; Oxberry, Geoffrey M.

2017-09-17

In this study, we consider two proper orthogonal decomposition (POD) methods for dimension reduction of dynamical systems. The first method (M1) uses only time snapshots of the solution, while the second method (M2) augments the snapshot set with time-derivative snapshots. The goal of the paper is to analyze and compare the approximation errors resulting from the two methods by using error bounds. We derive several new bounds of the error from POD model reduction by each of the two methods. The new error bounds involve a multiplicative factor depending on the time steps between the snapshots. For method M1 themore » factor depends on the second power of the time step, while for method 2 the dependence is on the fourth power of the time step, suggesting that method M2 can be more accurate for small between-snapshot intervals. However, three other factors also affect the size of the error bounds. These include (i) the norm of the second (for M1) and fourth derivatives (M2); (ii) the first neglected singular value and (iii) the spectral properties of the projection of the system’s Jacobian in the reduced space. Because of the interplay of these factors neither method is more accurate than the other in all cases. Finally, we present numerical examples demonstrating that when the number of collected snapshots is small and the first neglected singular value has a value of zero, method M2 results in a better approximation.« less

Model reduction of dynamical systems by proper orthogonal decomposition: Error bounds and comparison of methods using snapshots from the solution and the time derivatives [Proper orthogonal decomposition model reduction of dynamical systems: error bounds and comparison of methods using snapshots from the solution and the time derivatives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostova-Vassilevska, Tanya; Oxberry, Geoffrey M.

In this study, we consider two proper orthogonal decomposition (POD) methods for dimension reduction of dynamical systems. The first method (M1) uses only time snapshots of the solution, while the second method (M2) augments the snapshot set with time-derivative snapshots. The goal of the paper is to analyze and compare the approximation errors resulting from the two methods by using error bounds. We derive several new bounds of the error from POD model reduction by each of the two methods. The new error bounds involve a multiplicative factor depending on the time steps between the snapshots. For method M1 themore » factor depends on the second power of the time step, while for method 2 the dependence is on the fourth power of the time step, suggesting that method M2 can be more accurate for small between-snapshot intervals. However, three other factors also affect the size of the error bounds. These include (i) the norm of the second (for M1) and fourth derivatives (M2); (ii) the first neglected singular value and (iii) the spectral properties of the projection of the system’s Jacobian in the reduced space. Because of the interplay of these factors neither method is more accurate than the other in all cases. Finally, we present numerical examples demonstrating that when the number of collected snapshots is small and the first neglected singular value has a value of zero, method M2 results in a better approximation.« less

Calcium isotope analysis by mass spectrometry.

PubMed

Boulyga, Sergei F

2010-01-01

The variations in the isotopic composition of calcium caused by fractionation in heterogeneous systems and by nuclear reactions can provide insight into numerous biological, geological, and cosmic processes, and therefore isotopic analysis finds a wide spectrum of applications in cosmo- and geochemistry, paleoclimatic, nutritional, and biomedical studies. The measurement of calcium isotopic abundances in natural samples has challenged the analysts for more than three decades. Practically all Ca isotopes suffer from significant isobaric interferences, whereas low-abundant isotopes can be particularly affected by neighboring major isotopes. The extent of natural variations of stable isotopes appears to be relatively limited, and highly precise techniques are required to resolve isotopic effects. Isotope fractionation during sample preparation and measurements and instrumental mass bias can significantly exceed small isotope abundance variations in samples, which have to be investigated. Not surprisingly, a TIMS procedure developed by Russell et al. (Russell et al., 1978. Geochim Cosmochim Acta 42: 1075-1090) for Ca isotope measurements was considered as revolutionary for isotopic measurements in general, and that approach is used nowadays (with small modifications) for practically all isotopic systems and with different mass spectrometric techniques. Nevertheless, despite several decades of calcium research and corresponding development of mass spectrometers, the available precision and accuracy is still not always sufficient to achieve the challenging goals. The present article discusses figures of merits of presently used analytical methods and instrumentation, and attempts to critically assess their limitations. In Sections 2 and 3, mass spectrometric methods applied to precise stable isotope analysis and to the determination of (41)Ca are described. Section 4 contains a short summary of selected applications, and includes tracer experiments and the potential use

New Hampshire's Multi-Tiered Approach to Dropout Prevention. Snapshot: New Hampshire

ERIC Educational Resources Information Center

National High School Center, 2007

2007-01-01

Many states and districts across the country struggle with designing and implementing coherent dropout prevention initiatives that promote academic advancement, especially for special needs students, who drop out at much higher rates than the general student population. This "snapshot" describes New Hampshire's innovative use of data…

Prognostic models based on patient snapshots and time windows: Predicting disease progression to assisted ventilation in Amyotrophic Lateral Sclerosis.

PubMed

Carreiro, André V; Amaral, Pedro M T; Pinto, Susana; Tomás, Pedro; de Carvalho, Mamede; Madeira, Sara C

2015-12-01

Amyotrophic Lateral Sclerosis (ALS) is a devastating disease and the most common neurodegenerative disorder of young adults. ALS patients present a rapidly progressive motor weakness. This usually leads to death in a few years by respiratory failure. The correct prediction of respiratory insufficiency is thus key for patient management. In this context, we propose an innovative approach for prognostic prediction based on patient snapshots and time windows. We first cluster temporally-related tests to obtain snapshots of the patient's condition at a given time (patient snapshots). Then we use the snapshots to predict the probability of an ALS patient to require assisted ventilation after k days from the time of clinical evaluation (time window). This probability is based on the patient's current condition, evaluated using clinical features, including functional impairment assessments and a complete set of respiratory tests. The prognostic models include three temporal windows allowing to perform short, medium and long term prognosis regarding progression to assisted ventilation. Experimental results show an area under the receiver operating characteristics curve (AUC) in the test set of approximately 79% for time windows of 90, 180 and 365 days. Creating patient snapshots using hierarchical clustering with constraints outperforms the state of the art, and the proposed prognostic model becomes the first non population-based approach for prognostic prediction in ALS. The results are promising and should enhance the current clinical practice, largely supported by non-standardized tests and clinicians' experience. Copyright © 2015 Elsevier Inc. All rights reserved.

Stable Isotopes Reveal Rapid Cycling of Soil Nitrogen after Manure Application.

PubMed

Snider, David M; Wagner-Riddle, Claudia; Spoelstra, John

2017-03-01

Understanding the fate of applied nitrogen (N) in agricultural soils is important for agronomic, environmental, and human health reasons, but it is methodologically difficult to study at the field scale. Natural abundance stable isotope measurements (δN) were used in this field study with micrometeorological measurements of nitrous oxide (NO) emissions to identify the biogeochemical processes responsible for rapid N transformations immediately after application of liquid dairy manure. Fifteen samplings occurred between 16 Mar. 2012 and 5 Apr. 2013, with a focus on spring manure application (before and after) and a winter snowmelt period. Concentrations and δN values of ammonium (NH), nitrate (NO), NO, and total N were measured throughout the year. Approximately 56 (±7)% of the NH-N applied in the spring could not be accounted for 3 d after manure application and was presumably lost by ammonia volatilization before it was tilled into the soil and/or removed from the inorganic N pool by microbial assimilation. Almost all of the remaining manure-NH (95 ± 1.1%) was converted within 3 wk to NO and NO by nitrification and nitrifier-denitrification, respectively. The in situ N isotope effect for nitrification (ε) was calculated to be -32.0 (±5.3)‰. Overall, field-scale measurements of δN at natural abundance provided valuable information that was used to distinguish sources of NH (manure vs. soil organic N) and to follow the production and consumption of NO and the pathways of NO production in soil. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Possible application of laser isotope separation

NASA Technical Reports Server (NTRS)

Delionback, L. M.

1975-01-01

The laser isotope separation process is described and its special economic features discussed. These features are its low cost electric power operation, capital investment costs, and the costs of process materials.

Hydrogen isotope determination by TC/EA technique in application to volcanic glass as a window into secondary hydration

NASA Astrophysics Data System (ADS)

Martin, Erwan; Bindeman, Ilya; Balan, Etienne; Palandri, Jim; Seligman, Angela; Villemant, Benoit

2017-12-01

speciation. During magmatic degassing (from 6 wt% to 0.1 wt% water) the H2O/OH is expected to decrease from 2 to close to 0. However, our dataset suggests that during secondary glass hydration (from 0.1 wt% to 6 wt% water) the H2O/OH ratio decreases from 5 to 2, which is the complete opposite. Overall our results support the use of H-isotopes of volcanic glass to discuss the composition of meteoric waters and paleo-climate within a specific region. To this purpose, the volcanic glass has to be almost fully rehydrated in order to fingerprint the isotopic composition of the ambient environmental water. As rehydration is exponentially faster with increasing temperature, efficient rehydration taking months to years, may occur in a cooling volcanic deposits that are meters-thick and thus can remain at a few hundred °C for a years to hundreds of years after the eruption. Such deposits could then provide a snap-shot view of climatic conditions at the time of the studied eruption.

From Seurat to Snapshots: What the Visual Arts Could Contribute to Education.

ERIC Educational Resources Information Center

Duncum, Paul

1996-01-01

Advocates reconceptualizing visual arts as a core subject embodying key elements of experiential learning and critical thinking through an interdisciplinary approach. Illustrates this approach with a discussion of the interconnected issues surrounding family snapshots (social history, aesthetics, technological advancement). Discusses issues of…

Encrypted Three-dimensional Dynamic Imaging using Snapshot Time-of-flight Compressed Ultrafast Photography

PubMed Central

Liang, Jinyang; Gao, Liang; Hai, Pengfei; Li, Chiye; Wang, Lihong V.

2015-01-01

Compressed ultrafast photography (CUP), a computational imaging technique, is synchronized with short-pulsed laser illumination to enable dynamic three-dimensional (3D) imaging. By leveraging the time-of-flight (ToF) information of pulsed light backscattered by the object, ToF-CUP can reconstruct a volumetric image from a single camera snapshot. In addition, the approach unites the encryption of depth data with the compressed acquisition of 3D data in a single snapshot measurement, thereby allowing efficient and secure data storage and transmission. We demonstrated high-speed 3D videography of moving objects at up to 75 volumes per second. The ToF-CUP camera was applied to track the 3D position of a live comet goldfish. We have also imaged a moving object obscured by a scattering medium. PMID:26503834

Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

DOE PAGES

Hartig, Kyle C.; Ghebregziabher, Isaac; Jovanovic, Igor

2017-03-08

The ability to perform not only elementally but also isotopically sensitive detection and analysis at standoff distances is important for remote sensing applications in diverse ares, such as nuclear nonproliferation, environmental monitoring, geophysics, and planetary science. We demonstrate isotopically sensitive real-time standoff detection of uranium by the use of femtosecond filament-induced laser ablation molecular isotopic spectrometry. A uranium oxide molecular emission isotope shift of 0.05 ± 0.007 nm is reported at 593.6 nm. We implement both spectroscopic and acoustic diagnostics to characterize the properties of uranium plasma generated at different filament- uranium interaction points. The resulting uranium oxide emission exhibitsmore » a nearly constant signal-to-background ratio over the length of the filament, unlike the uranium atomic and ionic emission, for which the signal-to-background ratio varies significantly along the filament propagation. This is explained by the different rates of increase of plasma density and uranium oxide density along the filament length resulting from spectral and temporal evolution of the filament along its propagation. Lastly, the results provide a basis for the optimal use of filaments for standoff detection and analysis of uranium isotopes and indicate the potential of the technique for a wider range of remote sensing applications that require isotopic sensitivity.« less

Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartig, Kyle C.; Ghebregziabher, Isaac; Jovanovic, Igor

The ability to perform not only elementally but also isotopically sensitive detection and analysis at standoff distances is important for remote sensing applications in diverse ares, such as nuclear nonproliferation, environmental monitoring, geophysics, and planetary science. We demonstrate isotopically sensitive real-time standoff detection of uranium by the use of femtosecond filament-induced laser ablation molecular isotopic spectrometry. A uranium oxide molecular emission isotope shift of 0.05 ± 0.007 nm is reported at 593.6 nm. We implement both spectroscopic and acoustic diagnostics to characterize the properties of uranium plasma generated at different filament- uranium interaction points. The resulting uranium oxide emission exhibitsmore » a nearly constant signal-to-background ratio over the length of the filament, unlike the uranium atomic and ionic emission, for which the signal-to-background ratio varies significantly along the filament propagation. This is explained by the different rates of increase of plasma density and uranium oxide density along the filament length resulting from spectral and temporal evolution of the filament along its propagation. Lastly, the results provide a basis for the optimal use of filaments for standoff detection and analysis of uranium isotopes and indicate the potential of the technique for a wider range of remote sensing applications that require isotopic sensitivity.« less

Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

NASA Astrophysics Data System (ADS)

Hartig, Kyle C.; Ghebregziabher, Isaac; Jovanovic, Igor

2017-03-01

The ability to perform not only elementally but also isotopically sensitive detection and analysis at standoff distances is impor-tant for remote sensing applications in diverse ares, such as nuclear nonproliferation, environmental monitoring, geophysics, and planetary science. We demonstrate isotopically sensitive real-time standoff detection of uranium by the use of femtosecond filament-induced laser ablation molecular isotopic spectrometry. A uranium oxide molecular emission isotope shift of 0.05 ± 0.007 nm is reported at 593.6 nm. We implement both spectroscopic and acoustic diagnostics to characterize the properties of uranium plasma generated at different filament-uranium interaction points. The resulting uranium oxide emis-sion exhibits a nearly constant signal-to-background ratio over the length of the filament, unlike the uranium atomic and ionic emission, for which the signal-to-background ratio varies significantly along the filament propagation. This is explained by the different rates of increase of plasma density and uranium oxide density along the filament length resulting from spectral and temporal evolution of the filament along its propagation. The results provide a basis for the optimal use of filaments for standoff detection and analysis of uranium isotopes and indicate the potential of the technique for a wider range of remote sensing applications that require isotopic sensitivity.

Analysis of the site-specific carbon isotope composition of propane by gas source isotope ratio mass spectrometer

NASA Astrophysics Data System (ADS)

Piasecki, Alison; Sessions, Alex; Lawson, Michael; Ferreira, A. A.; Neto, E. V. Santos; Eiler, John M.

2016-09-01

Site-specific isotope ratio measurements potentially provide valuable information about the formation and degradation of complex molecules-information that is lost in conventional bulk isotopic measurements. Here we discuss the background and possible applications of such measurements, and present a technique for studying the site-specific carbon isotope composition of propane at natural abundance based on mass spectrometric analysis of the intact propane molecule and its fragment ions. We demonstrate the feasibility of this approach through measurements of mixtures of natural propane and propane synthesized with site-specific 13C enrichment, and we document the limits of precision of our technique. We show that mass balance calculations of the bulk δ13C of propane based on our site-specific measurements is generally consistent with independent constraints on bulk δ13C. We further demonstrate the accuracy of the technique, and illustrate one of its simpler applications by documenting the site-specific carbon isotope signature associated with gas phase diffusion of propane, confirming that our measurements conform to the predictions of the kinetic theory of gases. This method can be applied to propane samples of moderate size (tens of micromoles) isolated from natural gases. Thus, it provides a means of studying the site-specific stable isotope systematics of propane at natural isotope abundances on sample sizes that are readily recovered from many natural environments. This method may also serve as a model for future techniques that apply high-resolution mass spectrometry to study the site-specific isotopic distributions of larger organic molecules, with potential applications to biosynthesis, forensics and other geochemical subjects.

[Applications of stable isotope analysis in the trophic ecology studies of cephalopods].

PubMed

Li, Yun-Kai; Gong, Yi; Chen, Xin-Jun

2014-05-01

Cephalopods play an important role in marine food webs, however, knowledge about their complex life history, especially their feeding ecology, remains limited. With the rapidly increasing use of stable isotope analysis (SIA) in ecology, it becomes a powerful tool and complement of traditional methods for investigating the trophic ecology and migration patterns of invertebrates. Here, after summarizing the current methods for trophic ecology investigation of cephalopods, applications of SIA in studying the trophic ecology of cephalopods were reviewed, including the key issues such as standardization of available tissues for SIA analyzing, diet shift and migration patterns of cephalopods, with the aim of advancing its application in the biology of cephalopods in the future.

Isotope separation by laser means

DOEpatents

Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

1982-06-15

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Mg-Fe Isotope Systems of Mantle Xenoliths: Constrains on the Evolution of Siberian Craton

NASA Astrophysics Data System (ADS)

An, Y.; Kiseeva, E. S.; Sobolev, N. V.; Zhang, Z.

2017-12-01

Mantle xenoliths bring to the surface a variety of lithologies (dunites, lherzolites, harzburgites, wehrlites, eclogites, pyroxenites, and websterites) and represent snapshots of the geochemical processes that occur deep within the Earth. Recent improvements in the precision of the MC-ICP-MS measurements have allowed us to expand the amount of data on Mg and Fe isotopes for mantle-derived samples. For instance, to constrain the isotopic composition of the Earth based on the study of spinel and garnet peridotites (An et al., 2017; Teng et al., 2010), to trace the origin and to investigate the isotopic fractionation mechanism during metamorphic process using cratonic or orogenic eclogites (Li et al., 2011; Wang et al., 2012) and to reveal the metasomatism-induced mantle heterogeneity by pyroxenites (Hu et al., 2016). Numerous multi-stage modification events and mantle layering are detected in the subcontinental lithospheric mantle under the Siberian craton (Ashchepkov et al., 2008a; Sobolev et al., 1975, etc). Combined analyses of Mg and Fe isotopic systems could provide new constraints on the formation and evolution of the ancient cratonic mantle. In order to better constrain the magnitude and mechanism of inter-mineral Mg and Fe isotopic fractionations at high temperatures, systematic studies of mantle xenoliths are needed. For example, theoretical calculations and natural samples measurements have shown that large equilibrium Mg isotope fractionations controlled by the difference in coordination number of Mg among minerals could exist (Huang et al., 2013; Li et al., 2011). Thus, the Mg isotope geothermometer could help us trace the evolution history of ancient cratons. In this study we present Mg and Fe isotopic data for whole rocks and separated minerals (clinopyroxene (cpx) and garnet (grt)) from different types of mantle xenoliths (garnet pyroxenites, eclogites, grospydites and garnet peridotites) from a number of kimberlite pipes in Siberian craton (Udachnaya

Combining Solvent Isotope Effects with Substrate Isotope Effects in Mechanistic Studies of Alcohol and Amine Oxidation by Enzymes*

PubMed Central

Fitzpatrick, Paul F.

2014-01-01

Oxidation of alcohols and amines is catalyzed by multiple families of flavin-and pyridine nucleotide-dependent enzymes. Measurement of solvent isotope effects provides a unique mechanistic probe of the timing of the cleavage of the OH and NH bonds, necessary information for a complete description of the catalytic mechanism. The inherent ambiguities in interpretation of solvent isotope effects can be significantly decreased if isotope effects arising from isotopically labeled substrates are measured in combination with solvent isotope effects. The application of combined solvent and substrate (mainly deuterium) isotope effects to multiple enzymes is described here to illustrate the range of mechanistic insights that such an approach can provide. PMID:25448013

Ten Cities, 1997-1998: A Snapshot of Family Homelessness across America.

ERIC Educational Resources Information Center

Homes for the Homeless, Inc., New York, NY.

In 1997, the Institute for Children and Poverty of Homes for the Homeless joined with more than 58 organizations from 10 cities across the country to develop a national snapshot of family homelessness in the United States. Nearly 800 families were surveyed. This report presents the results of this research. The typical homeless family in the…

Snapshot of a Multi-Year Multidisciplinary Environmental Mapping and Restoration Project

ERIC Educational Resources Information Center

Lusignan, Molly; Abilock, Debbie

2008-01-01

This article presents a snapshot of the authors' first restoration project with young children which grew out of a fourth- and fifth-grade forestry curriculum. The restoration project was part of a long-term plan for enhancing the wild areas of the campus for wildlife habitat and for educational use. It is a native oak woodland and riparian…

#Frailty: A snapshot Twitter report on frailty knowledge translation.

PubMed

Jha, Sunita R; McDonagh, Julee; Prichard, Ros; Newton, Phillip J; Hickman, Louise D; Fung, Erik; Macdonald, Peter S; Ferguson, Caleb

2018-05-07

The objectives of this short report are to: (i) explore #Frailty Twitter activity over a six-month period; and (ii) provide a snapshot Twitter content analysis of #Frailty usage. A mixed-method study was conducted to explore Twitter data related to frailty. The primary search term was #Frailty. Objective 1: data were collected using Symplur analytics, including variables for total number of tweets, unique tweeters (users) and total number of impressions. Objective 2: a retrospectively conducted snapshot content analysis of 1500 #Frailty tweets was performed using TweetReach ™ . Over a six-month period (1 January 2017-31 June 2017), there was a total of 6545 #Frailty tweets, generating 14.8 million impressions across 3986 participants. Of the 1500 tweets (814 retweets; 202 replies; 484 original tweets), 56% were relevant to clinical frailty. The main contributors ('who') were as follows: the public (29%), researchers (25%), doctors (21%), organisations (18%) and other allied health professionals (7%). Tweet main message intention ('what') was public health/advocacy (41%), social communication (28%), research-based evidence/professional education (24%), professional opinion/case studies (15%) and general news/events (7%). Twitter is increasingly being used to communicate about frailty. It is important that thought leaders contribute to the conversation. There is potential to leverage Twitter to promote and disseminate frailty-related knowledge and research. © 2018 AJA Inc.

Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

PubMed Central

Hartig, Kyle C.; Ghebregziabher, Isaac; Jovanovic, Igor

2017-01-01

The ability to perform not only elementally but also isotopically sensitive detection and analysis at standoff distances is impor-tant for remote sensing applications in diverse ares, such as nuclear nonproliferation, environmental monitoring, geophysics, and planetary science. We demonstrate isotopically sensitive real-time standoff detection of uranium by the use of femtosecond filament-induced laser ablation molecular isotopic spectrometry. A uranium oxide molecular emission isotope shift of 0.05 ± 0.007 nm is reported at 593.6 nm. We implement both spectroscopic and acoustic diagnostics to characterize the properties of uranium plasma generated at different filament-uranium interaction points. The resulting uranium oxide emis-sion exhibits a nearly constant signal-to-background ratio over the length of the filament, unlike the uranium atomic and ionic emission, for which the signal-to-background ratio varies significantly along the filament propagation. This is explained by the different rates of increase of plasma density and uranium oxide density along the filament length resulting from spectral and temporal evolution of the filament along its propagation. The results provide a basis for the optimal use of filaments for standoff detection and analysis of uranium isotopes and indicate the potential of the technique for a wider range of remote sensing applications that require isotopic sensitivity. PMID:28272450

Fast T1 and T2 mapping methods: the zoomed U-FLARE sequence compared with EPI and snapshot-FLASH for abdominal imaging at 11.7 Tesla.

PubMed

Pastor, Géraldine; Jiménez-González, María; Plaza-García, Sandra; Beraza, Marta; Reese, Torsten

2017-06-01

A newly adapted zoomed ultrafast low-angle RARE (U-FLARE) sequence is described for abdominal imaging applications at 11.7 Tesla and compared with the standard echo-plannar imaging (EPI) and snapshot fast low angle shot (FLASH) methods. Ultrafast EPI and snapshot-FLASH protocols were evaluated to determine relaxation times in phantoms and in the mouse kidney in vivo. Owing to their apparent shortcomings, imaging artefacts, signal-to-noise ratio (SNR), and variability in the determination of relaxation times, these methods are compared with the newly implemented zoomed U-FLARE sequence. Snapshot-FLASH has a lower SNR when compared with the zoomed U-FLARE sequence and EPI. The variability in the measurement of relaxation times is higher in the Look-Locker sequences than in inversion recovery experiments. Respectively, the average T1 and T2 values at 11.7 Tesla are as follows: kidney cortex, 1810 and 29 ms; kidney medulla, 2100 and 25 ms; subcutaneous tumour, 2365 and 28 ms. This study demonstrates that the zoomed U-FLARE sequence yields single-shot single-slice images with good anatomical resolution and high SNR at 11.7 Tesla. Thus, it offers a viable alternative to standard protocols for mapping very fast parameters, such as T1 and T2, or dynamic processes in vivo at high field.

Preliminary Study: Application of Off-Axis ICOS to Determine Stable Carbon Isotope in Dissolved Inorganic Carbon

NASA Astrophysics Data System (ADS)

Kim, Y. T.; Lee, J. M.; Hwang, J. H.; Piao, J.; Woo, N. C.

2015-12-01

CO2 is one of the major causes for global climate change. Because stable carbon isotope ratio is used to trace carbon source, several analytical techniques likes IRMS (Isotope Ratio Mass Spectrometry) and LAS (Laser Absorption Spectrometry) were extensively used. Off-axis ICOS, a kind of LAS, has merits on long-term stability and field application, therefore it is widely being used in CCS (Carbon Capture and Storage) field. The aim of this study is to extend the application scope of OA-ICOS to determine dissolved inorganic carbon (DIC). Because OA-ICOS showed dependence of δ13C on CO2 concentration, data processing is required. We tested CO2 Carbon Isotope Analyzer (CCIA-36-EP, Los Gatos Research) with both reference gas (δ13C= -28.28‰) and aqueous solutions prepared by dissolving sodium bicarbonate standards (δ13C= -12.26‰ and +3.96‰). The differences of δ13C between reference and measurement values are plotted by CO2 concentrations, then compared. At first, we checked the similarity between our curve pattern for reference gas and Guillon's research (δ13C= -43.99‰) by other Analyzer. To analyze aqueous samples, more errors can be caused than gas analysis. The carbon isotope fractionation occurs during dissolving standard reagents and extracting DIC as CO2 gas form. This effect is mixed with CO2 concentration dependence effect, therefore the curve patterns are different with that for reference gas. Our experiments are done for various δ13C values. It could be an important point to use OA-ICOS to analyze DIC, too.

Exploring water cycle dynamics by sampling multiple stable water isotope pools in a developed landscape in Germany

NASA Astrophysics Data System (ADS)

Orlowski, Natalie; Kraft, Philipp; Pferdmenges, Jakob; Breuer, Lutz

2016-09-01

A dual stable water isotope (δ2H and δ18O) study was conducted in the developed (managed) landscape of the Schwingbach catchment (Germany). The 2-year weekly to biweekly measurements of precipitation, stream, and groundwater isotopes revealed that surface and groundwater are isotopically disconnected from the annual precipitation cycle but showed bidirectional interactions between each other. Apparently, snowmelt played a fundamental role for groundwater recharge explaining the observed differences to precipitation δ values. A spatially distributed snapshot sampling of soil water isotopes at two soil depths at 52 sampling points across different land uses (arable land, forest, and grassland) revealed that topsoil isotopic signatures were similar to the precipitation input signal. Preferential water flow paths occurred under forested soils, explaining the isotopic similarities between top- and subsoil isotopic signatures. Due to human-impacted agricultural land use (tilling and compression) of arable and grassland soils, water delivery to the deeper soil layers was reduced, resulting in significant different isotopic signatures. However, the land use influence became less pronounced with depth and soil water approached groundwater δ values. Seasonally tracing stable water isotopes through soil profiles showed that the influence of new percolating soil water decreased with depth as no remarkable seasonality in soil isotopic signatures was obvious at depths > 0.9 m and constant values were observed through space and time. Since classic isotope evaluation methods such as transfer-function-based mean transit time calculations did not provide a good fit between the observed and calculated data, we established a hydrological model to estimate spatially distributed groundwater ages and flow directions within the Vollnkirchener Bach subcatchment. Our model revealed that complex age dynamics exist within the subcatchment and that much of the runoff must has been stored

Tunable Light-Guide Image Processing Snapshot Spectrometer (TuLIPSS) for Earth and Moon Observations

NASA Astrophysics Data System (ADS)

Tkaczyk, T. S.; Alexander, D.; Luvall, J. C.; Wang, Y.; Dwight, J. G.; Pawlowsk, M. E.; Howell, B.; Tatum, P. F.; Stoian, R.-I.; Cheng, S.; Daou, A.

2018-02-01

A tunable light-guide image processing snapshot spectrometer (TuLIPSS) for Earth science research and observation is being developed through a NASA instrument incubator project with Rice University and Marshall Space Flight Center.

Radiogenic Isotopes As Paleoceanographic Tracers in Deep-Sea Corals: Advances in TIMS Measurements of Pb Isotopes and Application to Southern Ocean Corals

NASA Astrophysics Data System (ADS)

Wilson, D. J.; van de Flierdt, T.; Bridgestock, L. J.; Paul, M.; Rehkamper, M.; Robinson, L. F.; Adkins, J. F.

2014-12-01

Deep-sea corals have emerged as a valuable archive of deep ocean paleoceanographic change, with uranium-series dating providing absolute ages and the potential for centennial resolution. In combination with measurements of radiocarbon, neodymium isotopes and clumped isotopes, this archive has recently been exploited to reconstruct changes in ventilation, water mass sourcing and temperature in relation to millennial climate change. Lead (Pb) isotopes in both corals and seawater have also been used to track anthropogenic inputs through space and time and to trace transport pathways within the oceans. Better understanding of the oceanic Pb cycle is emerging from the GEOTRACES programme. However, while Pb isotopes have been widely used in environmental studies, their full potential as a (pre-anthropogenic) paleoceanographic tracer remains to be exploited. In deep-sea corals, challenges exist from low Pb concentrations in aragonite in comparison to secondary coatings, the potential for contamination, and the efficient elemental separation required for measurement by thermal ionisation mass spectrometry (TIMS). Here we discuss progress in measuring Pb isotopes in coral aragonite using a 207Pb-204Pb double spike on a ThermoFinnigan Triton TIMS. For a 2 ng NIST-981 Pb standard, the long term reproducibility (using 1011 Ω resistors) is ~1000 ppm (2 s.d.) on 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios. We now show that using a new 1012 Ω resistor to measure the small 204Pb beam improves the internal precision on these ratios from ~500 ppm (2 s.e.) to ~250 ppm (2 s.e.) and we envisage a potential improvement in the long term reproducibility as a consequence. We further assess the internal precision and external reproducibility of our method using a BCR-2 rock standard and an in-house coral standard. Preliminary evidence on the application of this method to natural samples is derived from cleaning experiments and replication tests on deep-sea corals from the Southern

5. Photographic copy of historic photography. Original snapshot print is ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. Photographic copy of historic photography. Original snapshot print is in narrative reports of the Lower Souris Migratory Waterfowl Refuge for the 1930s, on file at the headquarters of the J. Clark Salyer National Wildlife Refuge, Upham, North Dakota. DREDGING CHANNEL FOR THE SOURIS RIVER FOR DRAINAGE PURPOSES IN THE EARLY 20TH CENTURY - J. Clark Salyer National Wildlife Refuge Dams, Along Lower Souris River, Kramer, Bottineau County, ND

Illusory motion reversal is caused by rivalry, not by perceptual snapshots of the visual field.

PubMed

Kline, Keith; Holcombe, Alex O; Eagleman, David M

2004-10-01

In stroboscopic conditions--such as motion pictures--rotating objects may appear to rotate in the reverse direction due to under-sampling (aliasing). A seemingly similar phenomenon occurs in constant sunlight, which has been taken as evidence that the visual system processes discrete "snapshots" of the outside world. But if snapshots are indeed taken of the visual field, then when a rotating drum appears to transiently reverse direction, its mirror image should always appeared to reverse direction simultaneously. Contrary to this hypothesis, we found that when observers watched a rotating drum and its mirror image, almost all illusory motion reversals occurred for only one image at a time. This result indicates that the motion reversal illusion cannot be explained by snapshots of the visual field. The same result is found when the two images are presented within one visual hemifield, further ruling out the possibility that discrete sampling of the visual field occurs separately in each hemisphere. The frequency distribution of illusory reversal durations approximates a gamma distribution, suggesting perceptual rivalry as a better explanation for illusory motion reversal. After adaptation of motion detectors coding for the correct direction, the activity of motion-sensitive neurons coding for motion in the reverse direction may intermittently become dominant and drive the perception of motion.

Compelling Research Opportunities using Isotopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Isotopes are vital to the science and technology base of the US economy. Isotopes, both stable and radioactive, are essential tools in the growing science, technology, engineering, and health enterprises of the 21st century. The scientific discoveries and associated advances made as a result of the availability of isotopes today span widely from medicine to biology, physics, chemistry, and a broad range of applications in environmental and material sciences. Isotope issues have become crucial aspects of homeland security. Isotopes are utilized in new resource development, in energy from bio-fuels, petrochemical and nuclear fuels, in drug discovery, health care therapies andmore » diagnostics, in nutrition, in agriculture, and in many other areas. The development and production of isotope products unavailable or difficult to get commercially have been most recently the responsibility of the Department of Energy's Nuclear Energy program. The President's FY09 Budget request proposed the transfer of the Isotope Production program to the Department of Energy's Office of Science in Nuclear Physics and to rename it the National Isotope Production and Application program (NIPA). The transfer has now taken place with the signing of the 2009 appropriations bill. In preparation for this, the Nuclear Science Advisory Committee (NSAC) was requested to establish a standing subcommittee, the NSAC Isotope Subcommittee (NSACI), to advise the DOE Office of Nuclear Physics. The request came in the form of two charges: one, on setting research priorities in the short term for the most compelling opportunities from the vast array of disciplines that develop and use isotopes and two, on making a long term strategic plan for the NIPA program. This is the final report to address charge 1. NSACI membership is comprised of experts from the diverse research communities, industry, production, and homeland security. NSACI discussed research opportunities divided into three areas: (1

Carbon isotope ratios and isotopic correlations between components in fruit juices

NASA Astrophysics Data System (ADS)

Wierzchnicki, Ryszard

2013-04-01

Nowadays food products are defined by geographical origin, method of production and by some regulations concerning terms of their authenticity. Important data for confirm the authenticity of product are providing by isotopic methods of food control. The method checks crucial criteria which characterize the authenticity of inspected product. The European Union Regulations clearly show the tendency for application of the isotopic methods for food authenticity control (wine, honey, juice). The aim of the legislation steps is the protection of European market from possibility of the commercial frauds. Method of isotope ratio mass spectrometry is very effective tool for the use distinguishably the food products of various geographical origin. The basic problem for identification of the sample origin is the lack of databases of isotopic composition of components and information about the correlations of the data. The subject of the work was study the isotopic correlations existing between components of fruits. The chemical and instrumental methods of separation: water, sugars, organic acids and pulp from fruit were implemented. IRMS technique was used to measure isotopic composition of samples. The final results for original samples of fruits (apple, strawberry etc.) will be presented and discussed. Acknowledgement: This work was supported by the Polish Ministry of Science and Higher Education under grant NR12-0043-10/2010.

Defining a stable water isotope framework for isotope hydrology application in a large trans-boundary watershed (Russian Federation/Ukraine).

PubMed

Vystavna, Yuliya; Diadin, Dmytro; Huneau, Frédéric

2018-05-01

Stable isotopes of hydrogen ( 2 H) and oxygen ( 18 O) of the water molecule were used to assess the relationship between precipitation, surface water and groundwater in a large Russia/Ukraine trans-boundary river basin. Precipitation was sampled from November 2013 to February 2015, and surface water and groundwater were sampled during high and low flow in 2014. A local meteoric water line was defined for the Ukrainian part of the basin. The isotopic seasonality in precipitation was evident with depletion in heavy isotopes in November-March and an enrichment in April-October, indicating continental and temperature effects. Surface water was enriched in stable water isotopes from upstream to downstream sites due to progressive evaporation. Stable water isotopes in groundwater indicated that recharge occurs mainly during winter and spring. A one-year data set is probably not sufficient to report the seasonality of groundwater recharge, but this survey can be used to identify the stable water isotopes framework in a weakly gauged basin for further hydrological and geochemical studies.

Washington View: Not a Snapshot of Public Opinion but an Album

ERIC Educational Resources Information Center

Ferguson, Maria

2015-01-01

The columnist weighs in on the most recent PDK/Gallup poll. The real value of the poll, the author says, comes from looking at each response and then thinking about the connective tissue between and among them. The poll's 47-year history adds yet another layer of rich context. Uniquely, the poll provides not a snapshot of public opinion, rather an…

High-frequency field-deployable isotope analyzer for hydrological applications

Treesearch

Elena S.F. Berman; Manish Gupta; Chris Gabrielli; Tina Garland; Jeffrey J. McDonnell

2009-01-01

A high-frequency, field-deployable liquid water isotope analyzer was developed. The instrument was deployed for 4 contiguous weeks in the H. J. Andrews Experimental Forest Long-term Ecological Research site in western Oregon, where it was used for real-time measurement of the isotope ratios of precipitation and stream water during three large storm events. We were able...

Development and characterization of a snapshot Mueller matrix polarimeter for the determination of cervical cancer risk in the low resource setting

NASA Astrophysics Data System (ADS)

Ramella-Roman, Jessica C.; Gonzalez, Mariacarla; Chue-Sang, Joseph; Montejo, Karla; Krup, Karl; Srinivas, Vijaya; DeHoog, Edward; Madhivanan, Purnima

2018-04-01

Mueller Matrix polarimetry can provide useful information about the function and structure of the extracellular matrix. Mueller Matrix systems are sophisticated and costly optical tools that have been used primarily in the laboratory or in hospital settings. Here we introduce a low-cost snapshot Mueller Matrix polarimeter that that does not require external power, has no moving parts, and can acquire a full Mueller Matrix in less than 50 milliseconds. We utilized this technology in the study of cervical cancer in Mysore India, yet the system could be translated in multiple diagnostic applications.

12. Photographic copy of historic photograph. Original snapshot print can ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. Photographic copy of historic photograph. Original snapshot print can be found in narrative reports of the Lower Souris Migratory Waterfowl Refuge for the 1930s, on file at the headquarters of the J. Clark Salyer National Wildlife Refuge, Upham, North Dakota. GATES OF DAM 320 ON APRIL 9, 1936 WITH ICE ON WATER 50 INCHES THICK - J. Clark Salyer National Wildlife Refuge, Dam 320, Along Lower Souris River, Kramer, Bottineau County, ND

Finite mixture models for the computation of isotope ratios in mixed isotopic samples

NASA Astrophysics Data System (ADS)

Koffler, Daniel; Laaha, Gregor; Leisch, Friedrich; Kappel, Stefanie; Prohaska, Thomas

2013-04-01

Finite mixture models have been used for more than 100 years, but have seen a real boost in popularity over the last two decades due to the tremendous increase in available computing power. The areas of application of mixture models range from biology and medicine to physics, economics and marketing. These models can be applied to data where observations originate from various groups and where group affiliations are not known, as is the case for multiple isotope ratios present in mixed isotopic samples. Recently, the potential of finite mixture models for the computation of 235U/238U isotope ratios from transient signals measured in individual (sub-)µm-sized particles by laser ablation - multi-collector - inductively coupled plasma mass spectrometry (LA-MC-ICPMS) was demonstrated by Kappel et al. [1]. The particles, which were deposited on the same substrate, were certified with respect to their isotopic compositions. Here, we focus on the statistical model and its application to isotope data in ecogeochemistry. Commonly applied evaluation approaches for mixed isotopic samples are time-consuming and are dependent on the judgement of the analyst. Thus, isotopic compositions may be overlooked due to the presence of more dominant constituents. Evaluation using finite mixture models can be accomplished unsupervised and automatically. The models try to fit several linear models (regression lines) to subgroups of data taking the respective slope as estimation for the isotope ratio. The finite mixture models are parameterised by: • The number of different ratios. • Number of points belonging to each ratio-group. • The ratios (i.e. slopes) of each group. Fitting of the parameters is done by maximising the log-likelihood function using an iterative expectation-maximisation (EM) algorithm. In each iteration step, groups of size smaller than a control parameter are dropped; thereby the number of different ratios is determined. The analyst only influences some control

New Isotopic Tracers for Shale Gas and Hydraulic Fracturing Fluids

EPA Pesticide Factsheets

The combined application of geochemistry, stable isotopes (δ18O, δ2H), strontium isotopes (87Sr/86Sr), boron isotopes (δ11B), and radium isotopes (228Ra/226Ra) provides a unique methodology for tracing and monitoring shale gas and fracking fluids in the environment.

Application of stable isotope ratio analysis for biodegradation monitoring in groundwater

USGS Publications Warehouse

Hatzinger, Paul B.; Böhlke, John Karl; Sturchio, Neil C.

2013-01-01

Stable isotope ratio analysis is increasingly being applied as a tool to detect, understand, and quantify biodegradation of organic and inorganic contaminants in groundwater. An important feature of this approach is that it allows degradative losses of contaminants to be distinguished from those caused by non-destructive processes such as dilution, dispersion, and sorption. Recent advances in analytical techniques, and new approaches for interpreting stable isotope data, have expanded the utility of this method while also exposing complications and ambiguities that must be considered in data interpretations. Isotopic analyses of multiple elements in a compound, and multiple compounds in the environment, are being used to distinguish biodegradative pathways by their characteristic isotope effects. Numerical models of contaminant transport, degradation pathways, and isotopic composition are improving quantitative estimates of in situ contaminant degradation rates under realistic environmental conditions.

Environmental and biomedical applications of natural metal stable isotope variations

USGS Publications Warehouse

Bullen, T.D.; Walczyk, T.

2009-01-01

etal stable isotopes are now being used to trace metal contaminants in the environment and as indicators of human systemic function where metals play a role. Stable isotope abundance variations provide information about metal sources and the processes affecting metals in complex natural systems, complementing information gained from surrogate tracers, such as metal abundance ratios or biochemical markers of metal metabolism. The science is still in its infancy, but the results of initial studies confirm that metal stable isotopes can provide a powerful tool for forensic and biomedical investigations.

Spectrum slicer for snapshot spectral imaging

NASA Astrophysics Data System (ADS)

Tamamitsu, Miu; Kitagawa, Yutaro; Nakagawa, Keiichi; Horisaki, Ryoichi; Oishi, Yu; Morita, Shin-ya; Yamagata, Yutaka; Motohara, Kentaro; Goda, Keisuke

2015-12-01

We propose and demonstrate an optical component that overcomes critical limitations in our previously demonstrated high-speed multispectral videography-a method in which an array of periscopes placed in a prism-based spectral shaper is used to achieve snapshot multispectral imaging with the frame rate only limited by that of an image-recording sensor. The demonstrated optical component consists of a slicing mirror incorporated into a 4f-relaying lens system that we refer to as a spectrum slicer (SS). With its simple design, we can easily increase the number of spectral channels without adding fabrication complexity while preserving the capability of high-speed multispectral videography. We present a theoretical framework for the SS and its experimental utility to spectral imaging by showing real-time monitoring of a dynamic colorful event through five different visible windows.

Method for production of an isotopically enriched compound

DOEpatents

Watrous, Matthew G.

2012-12-11

A method is presented for producing and isolating an isotopically enriched compound of a desired isotope from a parent radionuclide. The method includes forming, or placing, a precipitate containing a parent radionuclide of the desired daughter isotope in a first reaction zone and allowing sufficient time for the parent to decay into the desired gaseous daughter radioisotope. The method further contemplates collecting the desired daughter isotope as a solid in a second reaction zone through the application of temperatures below the freezing point of the desired isotope to a second reaction zone that is connected to the first reaction zone. Specifically, a method is presented for producing isotopically enriched compounds of xenon, including the radioactive isotope Xe-131m and the stable isotope Xe-131.

Application of sulphur isotope ratios to examine weaning patterns and freshwater fish consumption in Roman Oxfordshire, UK

NASA Astrophysics Data System (ADS)

Nehlich, Olaf; Fuller, Benjamin T.; Jay, Mandy; Mora, Alice; Nicholson, Rebecca A.; Smith, Colin I.; Richards, Michael P.

2011-09-01

This study investigates the application of sulphur isotope ratios (δ 34S) in combination with carbon (δ 13C) and nitrogen (δ 15N) ratios to understand the influence of environmental sulphur on the isotopic composition of archaeological human and faunal remains from Roman era sites in Oxfordshire, UK. Humans ( n = 83), terrestrial animals ( n = 11), and freshwater fish ( n = 5) were analysed for their isotope values from four locations in the Thames River Valley, and a broad range of δ 34S values were found. The δ 34S values from the terrestrial animals were highly variable (-13.6‰ to +0.5‰), but the δ 34S values of the fish were clustered and 34S-depleted (-20.9‰ to -17.3‰). The results of the faunal remains suggest that riverine sulphur influenced the terrestrial sulphur isotopic signatures. Terrestrial animals were possibly raised on the floodplains of the River Thames, where highly 34S-depleted sulphur influenced the soil. The humans show the largest range of δ 34S values (-18.8‰ to +9.6‰) from any archaeological context to date. No differences in δ 34S values were found between the males (-7.8 ± 6.0‰) and females (-5.3 ± 6.8‰), but the females had a linear correlation ( R2 = 0.71; p < 0.0001) between their δ 15N and δ 34S compositions. These δ 34S results suggest a greater dietary variability for the inhabitants of Roman Oxfordshire than previously thought, with some individuals eating solely terrestrial protein resources and others showing a diet almost exclusively based on freshwater protein such as fish. Such large dietary variability was not visible by analysing only the carbon and nitrogen isotope ratios, and this research represents the largest and most detailed application of δ 34S analysis to examine dietary practices (including breastfeeding and weaning patterns) during the Romano-British Period.

Energy Transition Initiative: Island Energy Snapshot - U.S. Virgin Islands (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2015-03-01

This profile provides a snapshot of the energy landscape of the U.S. Virgin Islands (USVI) - St. Thomas, St. John, and St. Croix. The Virgin Islands archipelago makes up the northern portion of the Lesser Antilles and the western island group of the Leeward Islands, forming the border between the Atlantic Ocean and the Caribbean Sea.

Integrated carbon and chlorine isotope modeling: applications to chlorinated aliphatic hydrocarbons dechlorination.

PubMed

Jin, Biao; Haderlein, Stefan B; Rolle, Massimo

2013-02-05

We propose a self-consistent method to predict the evolution of carbon and chlorine isotope ratios during degradation of chlorinated hydrocarbons. The method treats explicitly the cleavage of isotopically different C-Cl bonds and thus considers, simultaneously, combined carbon-chlorine isotopologues. To illustrate the proposed modeling approach we focus on the reductive dehalogenation of chlorinated ethenes. We compare our method with the currently available approach, in which carbon and chlorine isotopologues are treated separately. The new approach provides an accurate description of dual-isotope effects regardless of the extent of the isotope fractionation and physical characteristics of the experimental system. We successfully applied the new approach to published experimental results on dehalogenation of chlorinated ethenes both in well-mixed systems and in situations where mass-transfer limitations control the overall rate of biodegradation. The advantages of our self-consistent dual isotope modeling approach proved to be most evident when isotope fractionation factors of carbon and chlorine differed significantly and for systems with mass-transfer limitations, where both physical and (bio)chemical transformation processes affect the observed isotopic values.

Application of zinc isotope tracer technology in tracing soil heavy metal pollution

NASA Astrophysics Data System (ADS)

Norbu, Namkha; Wang, Shuguang; Xu, Yan; Yang, Jianqiang; Liu, Qiang

2017-08-01

Recent years the soil heavy metal pollution has become increasingly serious, especially the zinc pollution. Due to the complexity of this problem, in order to prevent and treat the soil pollution, it's crucial to accurately and quickly find out the pollution sources and control them. With the development of stable isotope tracer technology, it's able to determine the composition of zinc isotope. Based on the theory of zinc isotope tracer technique, and by means of doing some latest domestic and overseas literature research about the zinc isotope multi-receiving cups of inductively coupled plasma mass spectrometer (MC-ICP-MS) testing technology, this paper summarized the latest research results about the pollution tracer of zinc isotope, and according to the deficiencies and existing problems of previous research, made outlooks of zinc isotope fractionation mechanism, repository establishment and tracer multiple solutions.

Calcium Isotope Analysis by Mass Spectrometry

NASA Astrophysics Data System (ADS)

Boulyga, S.; Richter, S.

2010-12-01

The variations in the isotopic composition of calcium caused by fractionation in heterogeneous systems and by nuclear reactions can provide insight into numerous biological, geological, and cosmic processes, and therefore isotopic analysis finds a wide spectrum of applications in cosmo- and geochemistry, paleoclimatic, nutritional, and biomedical studies. The measurement of calcium isotopic abundances in natural samples has challenged the analysts for more than three decades. Practically all Ca isotopes suffer from significant isobaric interferences, whereas low-abundant isotopes can be particularly affected by neighboring major isotopes. The extent of natural variations of stable isotopes appears to be relatively limited, and highly precise techniques are required to resolve isotopic effects. Isotope fractionation during sample preparation and measurements and instrumental mass bias can significantly exceed small isotope abundance variations in samples, which have to be investigated. Not surprisingly, a TIMS procedure developed by Russell et al. (Russell et al., 1978. Geochim Cosmochim Acta 42: 1075-1090) for Ca isotope measurements was considered as revolutionary for isotopic measurements in general, and that approach is used nowadays (with small modifications) for practically all isotopic systems and with different mass spectrometric techniques. Nevertheless, despite several decades of calcium research and corresponding development of mass spectrometers, the available precision and accuracy is still not always sufficient to achieve the challenging goals. This presentation discusses figures of merits of presently used analytical methods and instrumentation, and attempts to critically assess their limitations. Additionally, the availability of Ca isotope reference materials will be discussed.

APPLICATION OF ISOTOPE ENCEPHALOGRAPHY AND ELECTROENCEPHALOSCOPY FOR LOCALIZATION OF BRAIN TUMOURS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shamov, V.N.; Badmayev, C.N.; Bekhtereva, N.P.

1959-10-31

The problems of diagnosis and localization of brain tumors in some cases present many difficulities and make the neurosurgeon seek for additional methods of investigation. In such circumstances usage of the tracer technique in diagnostics is of considerable help, as it has obvious advantages compared with other methods of investigation, such as safety, painlessness, non-traumatism, absence of undesirable after effects, accuracy, and relative simplicity. The present communication is based on the results of clinical observations on 150 patients with verified brain tumors. Analyses of the data show that the accuracy of the brain tumor localizations vary, depending upon the depthmore » of the tumor site and conceniration of labelled material in the area of tumor growth. The diagnostic value of the method is doubtful in cases of tumors of posterior fossa, base of the brain, or the lesions of median line. The application of isotope encephalography is successfully supplemented by the new method of investigations, i.e., electroencephaloscopy, which allows the localization of deeply set tumors. Possibilities and limitations of the method are discussed. It is concluded that the isotope encephalography and electroencephaloscopy represent very valuable diagnostic methods which alongside with other auxiliary methods are widely used in diagnosis of brain tumors. (C.H.)« less

Potential Nano-Enabled Environmental Applications for Radionuclides

EPA Pesticide Factsheets

This document provides information about nanotechnology materials and processes that may be applicable when cleaning up radioactively contaminated sites or materials, and presents a snapshot of lessons learned in nano-science and engineering.

Isotope Geochemistry for Comparative Planetology of Exoplanets

NASA Technical Reports Server (NTRS)

Mandt, K. E.; Atreya, S.; Luspay-Kuti, A.; Mousis, O.; Simon, A.; Hofstadter, M. D.

2017-01-01

Isotope geochemistry has played a critical role in understanding processes at work in and the history of solar system bodies. Application of these techniques to exoplanets would be revolutionary and would allow comparative planetology with the formation and evolution of exoplanet systems. The roadmap for comparative planetology of the origins and workings of exoplanets involves isotopic geochemistry efforts in three areas: (1) technology development to expand observations of the isotopic composition of solar system bodies and expand observations to isotopic composition of exoplanet atmospheres; (2) theoretical modeling of how isotopes fractionate and the role they play in evolution of exoplanetary systems, atmospheres, surfaces and interiors; and (3) laboratory studies to constrain isotopic fractionation due to processes at work throughout the solar system.

Computer Generated Snapshot of Our Sun's Magnetic Field

NASA Technical Reports Server (NTRS)

2003-01-01

These banana-shaped loops are part of a computer-generated snapshot of our sun's magnetic field. The solar magnetic-field lines loop through the sun's corona, break through the sun's surface, and cornect regions of magnetic activity, such as sunspots. This image --part of a magnetic-field study of the sun by NASA's Allen Gary -- shows the outer portion (skins) of interconnecting systems of hot (2 million degrees Kelvin) coronal loops within and between two active magnetic regions on opposite sides of the sun's equator. The diameter of these coronal loops at their foot points is approximately the same size as the Earth's radius (about 6,000 kilometers).

The long-solved problem of the best-fit straight line: application to isotopic mixing lines

NASA Astrophysics Data System (ADS)

Wehr, Richard; Saleska, Scott R.

2017-01-01

It has been almost 50 years since York published an exact and general solution for the best-fit straight line to independent points with normally distributed errors in both x and y. York's solution is highly cited in the geophysical literature but almost unknown outside of it, so that there has been no ebb in the tide of books and papers wrestling with the problem. Much of the post-1969 literature on straight-line fitting has sown confusion not merely by its content but by its very existence. The optimal least-squares fit is already known; the problem is already solved. Here we introduce the non-specialist reader to York's solution and demonstrate its application in the interesting case of the isotopic mixing line, an analytical tool widely used to determine the isotopic signature of trace gas sources for the study of biogeochemical cycles. The most commonly known linear regression methods - ordinary least-squares regression (OLS), geometric mean regression (GMR), and orthogonal distance regression (ODR) - have each been recommended as the best method for fitting isotopic mixing lines. In fact, OLS, GMR, and ODR are all special cases of York's solution that are valid only under particular measurement conditions, and those conditions do not hold in general for isotopic mixing lines. Using Monte Carlo simulations, we quantify the biases in OLS, GMR, and ODR under various conditions and show that York's general - and convenient - solution is always the least biased.

A Snapshot Survey of The Most Massive Clusters of Galaxies

NASA Astrophysics Data System (ADS)

Ebeling, Harald

2007-07-01

We propose the continuation of our highly successful SNAPshot survey of a sample of 125 very X-ray luminous clusters in the redshift range 0.3-0.7. As demonstrated by the 25 snapshots obtained so far in Cycle14 and Cycle15 these systems frequently exhibit strong gravitational lensing as well as spectacular examples of violent galaxy interactions. The proposed observations will provide important constraints on the cluster mass distributions, the physical nature of galaxy-galaxy and galaxy-gas interactions in cluster cores, and a set of optically bright, lensed galaxies for further 8-10m spectroscopy. All of our primary science goals require only the detection and characterisation of high-surface-brightness features and are thus achievable even at the reduced sensitivity of WFPC2. Because of their high redshift and thus compact angular scale our target clusters are less adversely affected by the smaller field of view of WFPC2 than more nearby systems. Acknowledging the broad community interest in this sample we waive our data rights for these observations. Due to a clerical error at STScI our approved Cycle15 SNAP program was barred from execution for 3 months and only 6 observations have been performed to date - reinstating this SNAP at Cycle16 priority is of paramount importance to reach meaningful statistics.

Managing the Transition to Ninth Grade in a Comprehensive Urban High School. Snapshot

ERIC Educational Resources Information Center

Smith, Thomas J.

2007-01-01

This "snapshot" illustrates how one school is managing to make a positive difference for ninth graders. It describes the Ninth Grade Success Academy, a school-within-a-school at Thomas A. Edison High School in Philadelphia, Pennsylvania, which has a number of features specifically designed to help ninth-graders make successful…

Zinc isotope fractionation during magmatic differentiation and the isotopic composition of the bulk Earth

USGS Publications Warehouse

Chen, Heng; Savage, Paul S.; Teng, Fang-Zehn; Helz, Rosalind T.; Moynier, Frédéric

2013-01-01

he zinc stable isotope system has been successfully applied to many and varied fields in geochemistry, but to date it is still not completely clear how this isotope system is affected by igneous processes. In order to evaluate the potential application of Zn isotopes as a proxy for planetary differentiation and volatile history, it is important to constrain the magnitude of Zn isotopic fractionation induced by magmatic differentiation. In this study we present high-precision Zn isotope analyses of two sets of chemically diverse, cogenetic samples from Kilauea Iki lava lake, Hawaii, and Hekla volcano, Iceland, which both show clear evidence of having undergone variable and significant degrees of magmatic differentiation. The Kilauea Iki samples display small but resolvable variations in Zn isotope composition (0.26‰66Zn66Zn defined as the per mille deviation of a sample's 66Zn/64Zn compositional ratio from the JMC-Lyon standard), with the most differentiated lithologies exhibiting more positive δ66Zn values. This fractionation is likely a result of the crystallization of olivine and/or Fe–Ti oxides, which can both host Zn in their crystal structures. Samples from Hekla have a similar range of isotopic variation (0.22‰66Zn66Zn=0.28±0.05‰ (2s.d.).

Archean Pb Isotope Evolution: Implications for the Early Earth.

NASA Astrophysics Data System (ADS)

Vervoort, J. D.; Thorpe, R.; Albarede, F.; Blichert-Toft, J.

2008-12-01

The U-Pb isotope system provides us with a powerful tool for understanding the chemical evolution of the Earth. Pb isotopes in Archean rocks, however, have not been widely utilized because U mobility makes initial Pb isotope ratios from old silicate rocks difficult, if not impossible, to determine. Galenas in syngenetic volcanogenic massive sulfide (VMS) deposits, however, provide snapshots of initial Pb ratios because their Pb isotopic composition is time invariant at their formation (U/Pb=0). The Pb isotopic record from galenas from rocks of all age have been utilized for over 70 years to answer a wide range of scientific problems beginning with Al Nier's pioneering work analyzing Pb isotopes in the 1930's but are no longer widely used by the isotopic community because they have been produced by older TIMS techniques. We have begun a re-examination of Archean Pb by an extensive analysis of over 100 galena samples from Archean VMS deposits throughout the Superior and Slave Provinces in Canada as well as from other VMS deposits in Finland, South Africa and Western Australia. The goal of this work is to provide modern, high precision measurements and update an old, but venerable, Pb isotopic data set. We feel these data provide important constraints on not only the Pb isotopic evolution of the Earth, but planetary differentiation and recycling processes operating in the first 2 b.y. of Earth's history. Our analytical techniques include dissolving the Pb sulfide minerals, purifying them with ion chromatography, and analyzing them using MC-ICPMS at both Washington State University (Neptune) and Ecole Normale Superieure in Lyon, France (Nu). All Pb solutions are doped with Tl in order to correct for mass fractionation. In this abstract we report preliminary galena Pb isotope data from 6 VMS deposits in the Abitibi greenstone belt: Chibougamu, Matagami, Noranda, Normetal, Timmins, and Val d"Or. These deposits are all approximately 2.7 Ga in age but in detail vary from 2

Application of stable isotope analysis for detecting filial cannibalism.

PubMed

Sogabe, Atsushi; Hamaoka, Hideki; Fukuta, Atsushi; Shibata, Jun-Ya; Shoji, Jun; Omori, Koji

2017-07-01

A novel type of filial cannibalism has been reported in pipefishes, in which the eggs are absorbed through the male's brood-pouch epithelium. The present study explored the applicability of stable isotope analysis for the detection of paternal brood cannibalism in the seaweed pipefish Syngnathus schlegeli. As expected, the δ 15 N values for liver, which conveys short-term dietary information about the recent reproductive season, were higher in males than in females. In contrast, the δ 15 N values for muscle, which reflects longer-term feeding habits that span both the reproductive and non-reproductive seasons, did not significantly differ between the sexes. This finding indicates that males occupy a higher trophic position than females only during the reproductive season, and it is probable that this difference is a result of paternal uptake of nutrients from embryos in the brood pouch. Copyright © 2017 Elsevier B.V. All rights reserved.

Energy Transition Initiative: Island Energy Snapshot - Puerto Rico (Fact Sheet); NREL(National Renewable Energy Laboratory)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2015-03-01

This profile provides a snapshot of the energy landscape of the Commonwealth of Puerto Rico - a U.S. territory located about 60 miles east of the Dominican Republic and directly west of the U.S. Virgin Islands.

Snapshot linear-Stokes imaging spectropolarimeter using division-of-focal-plane polarimetry and integral field spectroscopy.

PubMed

Mu, Tingkui; Pacheco, Shaun; Chen, Zeyu; Zhang, Chunmin; Liang, Rongguang

2017-02-13

In this paper, the design and experimental demonstration of a snapshot linear-Stokes imaging spectropolarimeter (SLSIS) is presented. The SLSIS, which is based on division-of-focal-plane polarimetry with four parallel linear polarization channels and integral field spectroscopy with numerous slit dispersive paths, has no moving parts and provides video-rate Stokes-vector hyperspectral datacubes. It does not need any scanning in the spectral, spatial or polarization dimension and offers significant advantages of rapid reconstruction without heavy computation during post-processing. The principle and the experimental setup of the SLSIS are described in detail. The image registration, Stokes spectral reconstruction and calibration procedures are included, and the system is validated using measurements of tungsten light and a static scene. The SLSIS's snapshot ability to resolve polarization spectral signatures is demonstrated using measurements of a dynamic scene.

Snapshot linear-Stokes imaging spectropolarimeter using division-of-focal-plane polarimetry and integral field spectroscopy

PubMed Central

Mu, Tingkui; Pacheco, Shaun; Chen, Zeyu; Zhang, Chunmin; Liang, Rongguang

2017-01-01

In this paper, the design and experimental demonstration of a snapshot linear-Stokes imaging spectropolarimeter (SLSIS) is presented. The SLSIS, which is based on division-of-focal-plane polarimetry with four parallel linear polarization channels and integral field spectroscopy with numerous slit dispersive paths, has no moving parts and provides video-rate Stokes-vector hyperspectral datacubes. It does not need any scanning in the spectral, spatial or polarization dimension and offers significant advantages of rapid reconstruction without heavy computation during post-processing. The principle and the experimental setup of the SLSIS are described in detail. The image registration, Stokes spectral reconstruction and calibration procedures are included, and the system is validated using measurements of tungsten light and a static scene. The SLSIS’s snapshot ability to resolve polarization spectral signatures is demonstrated using measurements of a dynamic scene. PMID:28191819

Converting isotope ratios to diet composition - the use of mixing models - June 2010

EPA Science Inventory

One application of stable isotope analysis is to reconstruct diet composition based on isotopic mass balance. The isotopic value of a consumer’s tissue reflects the isotopic values of its food sources proportional to their dietary contributions. Isotopic mixing models are used ...

Acquisition of a full-resolution image and aliasing reduction for a spatially modulated imaging polarimeter with two snapshots

PubMed Central

Zhang, Jing; Yuan, Changan; Huang, Guohua; Zhao, Yinjun; Ren, Wenyi; Cao, Qizhi; Li, Jianying; Jin, Mingwu

2018-01-01

A snapshot imaging polarimeter using spatial modulation can encode four Stokes parameters allowing instantaneous polarization measurement from a single interferogram. However, the reconstructed polarization images could suffer a severe aliasing signal if the high-frequency component of the intensity image is prominent and occurs in the polarization channels, and the reconstructed intensity image also suffers reduction of spatial resolution due to low-pass filtering. In this work, a method using two anti-phase snapshots is proposed to address the two problems simultaneously. The full-resolution target image and the pure interference fringes can be obtained from the sum and the difference of the two anti-phase interferograms, respectively. The polarization information reconstructed from the pure interference fringes does not contain the aliasing signal from the high-frequency component of the object intensity image. The principles of the method are derived and its feasibility is tested by both computer simulation and a verification experiment. This work provides a novel method for spatially modulated imaging polarization technology with two snapshots to simultaneously reconstruct a full-resolution object intensity image and high-quality polarization components. PMID:29714224

The long-solved problem of the best-fit straight line: Application to isotopic mixing lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wehr, Richard; Saleska, Scott R.

It has been almost 50 years since York published an exact and general solution for the best-fit straight line to independent points with normally distributed errors in both x and y. York's solution is highly cited in the geophysical literature but almost unknown outside of it, so that there has been no ebb in the tide of books and papers wrestling with the problem. Much of the post-1969 literature on straight-line fitting has sown confusion not merely by its content but by its very existence. The optimal least-squares fit is already known; the problem is already solved. Here we introducemore » the non-specialist reader to York's solution and demonstrate its application in the interesting case of the isotopic mixing line, an analytical tool widely used to determine the isotopic signature of trace gas sources for the study of biogeochemical cycles. The most commonly known linear regression methods – ordinary least-squares regression (OLS), geometric mean regression (GMR), and orthogonal distance regression (ODR) – have each been recommended as the best method for fitting isotopic mixing lines. In fact, OLS, GMR, and ODR are all special cases of York's solution that are valid only under particular measurement conditions, and those conditions do not hold in general for isotopic mixing lines. Here, using Monte Carlo simulations, we quantify the biases in OLS, GMR, and ODR under various conditions and show that York's general – and convenient – solution is always the least biased.« less

The long-solved problem of the best-fit straight line: Application to isotopic mixing lines

DOE PAGES

Wehr, Richard; Saleska, Scott R.

2017-01-03

It has been almost 50 years since York published an exact and general solution for the best-fit straight line to independent points with normally distributed errors in both x and y. York's solution is highly cited in the geophysical literature but almost unknown outside of it, so that there has been no ebb in the tide of books and papers wrestling with the problem. Much of the post-1969 literature on straight-line fitting has sown confusion not merely by its content but by its very existence. The optimal least-squares fit is already known; the problem is already solved. Here we introducemore » the non-specialist reader to York's solution and demonstrate its application in the interesting case of the isotopic mixing line, an analytical tool widely used to determine the isotopic signature of trace gas sources for the study of biogeochemical cycles. The most commonly known linear regression methods – ordinary least-squares regression (OLS), geometric mean regression (GMR), and orthogonal distance regression (ODR) – have each been recommended as the best method for fitting isotopic mixing lines. In fact, OLS, GMR, and ODR are all special cases of York's solution that are valid only under particular measurement conditions, and those conditions do not hold in general for isotopic mixing lines. Here, using Monte Carlo simulations, we quantify the biases in OLS, GMR, and ODR under various conditions and show that York's general – and convenient – solution is always the least biased.« less

Improvements in Precise and Accurate Isotope Ratio Determination via LA-MC-ICP-MS by Application of an Alternative Data Reduction Protocol

NASA Astrophysics Data System (ADS)

Fietzke, J.; Liebetrau, V.; Guenther, D.; Frische, M.; Zumholz, K.; Hansteen, T. H.; Eisenhauer, A.

2008-12-01

An alternative approach for the evaluation of isotope ratio data using LA-MC-ICP-MS will be presented. In contrast to previously applied methods it is based on the simultaneous responses of all analyte isotopes of interest and the relevant interferences without performing a conventional background correction. Significant improvements in precision and accuracy can be achieved when applying this new method and will be discussed based on the results of two first methodical applications: a) radiogenic and stable Sr isotopes in carbonates b) stable chlorine isotopes of pyrohydrolytic extracts. In carbonates an external reproducibility of the 87Sr/86Sr ratios of about 19 ppm (RSD) was achieved, an improvement of about a factor of 5. For recent and sub-recent marine carbonates a mean radiogenic strontium isotope ratio 87Sr/86Sr of 0.709170±0.000007 (2SE) was determined, which agrees well with the value of 0.7091741±0.0000024 (2SE) reported for modern sea water [1,2]. Stable chlorine isotope ratios were determined ablating pyrohydrolytic extracts with a reproducibility of about 0.05‰ (RSD). For basaltic reference material JB1a and JB2 chlorine isotope ratios were determined relative to SMOC (standard mean ocean chlorinity) δ37ClJB-1a = (-0.99±0.06) ‰ and δ37ClJB-1a = (-0.60±0.03) ‰ (SD), respectively, in accordance with published data [3]. The described strategies for data reduction are considered to be generally applicable for all isotope ratio measurements using LA-MC-ICP-MS. [1] J.M. McArthur, D. Rio, F. Massari, D. Castradori, T.R. Bailey, M. Thirlwall, S. Houghton, Palaeogeo. Palaeoclim. Palaeoeco., 2006, 242 (126), doi: 10.1016/j.palaeo.2006.06.004 [2] J. Fietzke, V. Liebetrau, D. Guenther, K. Guers, K. Hametner, K. Zumholz, T.H. Hansteen and A. Eisenhauer, J. Anal. At. Spectrom., 2008, 23, 955-961, doi:10.1039/B717706B [3] J. Fietzke, M. Frische, T.H. Hansteen and A. Eisenhauer, J. Anal. At. Spectrom., 2008, 23, 769-772, doi:10.1039/B718597A

Application Of Stable Isotope Analysis To Study Temporal Changes In Foraging Ecology In A Highly Endangered Amphibian

PubMed Central

Gillespie, J. Hayley

2013-01-01

Background Understanding dietary trends for endangered species may be essential to assessing the effects of ecological disturbances such as habitat modification, species introductions or global climate change. Documenting temporal variation in prey selection may also be crucial for understanding population dynamics. However, the rarity, secretive behaviours and obscure microhabitats of some endangered species can make direct foraging observations difficult or impossible. Furthermore, the lethality or invasiveness of some traditional methods of dietary analysis (e.g. gut contents analysis, gastric lavage) makes them inappropriate for such species. Stable isotope analysis facilitates non-lethal, indirect analysis of animal diet that has unrealized potential in the conservation of endangered organisms, particularly amphibians. Methodology/findings I determined proportional contributions of aquatic macroinvertebrate prey to the diet of an endangered aquatic salamander Eurycea sosorum over a two-year period using stable isotope analysis of 13/12C and 15/14N and the Bayesian stable isotope mixing model SIAR. I calculated Strauss’ dietary electivity indices by comparing these proportions with changing relative abundance of potential prey species through time. Stable isotope analyses revealed that a previously unknown prey item (soft-bodied planarian flatworms in the genus Dugesia) made up the majority of E. sosorum diet. Results also demonstrate that E. sosorum is an opportunistic forager capable of diet switching to include a greater proportion of alternative prey when Dugesia populations decline. There is also evidence of intra-population dietary variation. Conclusions/significance Effective application of stable isotope analysis can help circumvent two key limitations commonly experienced by researchers of endangered species: the inability to directly observe these species in nature and the invasiveness or lethality of traditional methods of dietary analysis. This

Mass fractionation processes of transition metal isotopes

NASA Astrophysics Data System (ADS)

Zhu, X. K.; Guo, Y.; Williams, R. J. P.; O'Nions, R. K.; Matthews, A.; Belshaw, N. S.; Canters, G. W.; de Waal, E. C.; Weser, U.; Burgess, B. K.; Salvato, B.

2002-06-01

Recent advances in mass spectrometry make it possible to utilise isotope variations of transition metals to address some important issues in solar system and biological sciences. Realisation of the potential offered by these new isotope systems however requires an adequate understanding of the factors controlling their isotope fractionation. Here we show the results of a broadly based study on copper and iron isotope fractionation during various inorganic and biological processes. These results demonstrate that: (1) naturally occurring inorganic processes can fractionate Fe isotope to a detectable level even at temperature ˜1000°C, which challenges the previous view that Fe isotope variations in natural system are unique biosignatures; (2) multiple-step equilibrium processes at low temperatures may cause large mass fractionation of transition metal isotopes even when the fractionation per single step is small; (3) oxidation-reduction is an importation controlling factor of isotope fractionation of transition metal elements with multiple valences, which opens a wide range of applications of these new isotope systems, ranging from metal-silicate fractionation in the solar system to uptake pathways of these elements in biological systems; (4) organisms incorporate lighter isotopes of transition metals preferentially, and transition metal isotope fractionation occurs stepwise along their pathways within biological systems during their uptake.

Advances in primate stable isotope ecology-Achievements and future prospects.

PubMed

Crowley, Brooke E; Reitsema, Laurie J; Oelze, Vicky M; Sponheimer, Matt

2016-10-01

Stable isotope biogeochemistry has been used to investigate foraging ecology in non-human primates for nearly 30 years. Whereas early studies focused on diet, more recently, isotopic analysis has been used to address a diversity of ecological questions ranging from niche partitioning to nutritional status to variability in life history traits. With this increasing array of applications, stable isotope analysis stands to make major contributions to our understanding of primate behavior and biology. Most notably, isotopic data provide novel insights into primate feeding behaviors that may not otherwise be detectable. This special issue brings together some of the recent advances in this relatively new field. In this introduction to the special issue, we review the state of isotopic applications in primatology and its origins and describe some developing methodological issues, including techniques for analyzing different tissue types, statistical approaches, and isotopic baselines. We then discuss the future directions we envision for the field of primate isotope ecology. Am. J. Primatol. 78:995-1003, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Controls on the barium isotope compositions of marine sediments

NASA Astrophysics Data System (ADS)

Bridgestock, Luke; Hsieh, Yu-Te; Porcelli, Donald; Homoky, William B.; Bryan, Allison; Henderson, Gideon M.

2018-01-01

The accumulation of barium (Ba) in marine sediments is considered to be a robust proxy for export production, although this application can be limited by uncertainty in BaSO4 preservation and sediment mass accumulation rates. The Ba isotope compositions of marine sediments could potentially record insights into past changes in the marine Ba cycle, which should be insensitive to these limitations, enabling more robust interpretation of sedimentary Ba as a proxy. To investigate the controls on the Ba isotope compositions of marine sediments and their potential for paleo-oceanographic applications, we present the first Ba isotope compositions results for sediments, as well as overlying seawater depth profiles collected in the South Atlantic. Variations in Ba isotope compositions of the sediments predominantly reflect changes in the relative contributions of detrital and authigenic Ba sources, with open-ocean sediments constraining the isotope composition of authigenic Ba to be δ 138/134Ba ≈ + 0.1 ‰. This value is consistent with the average isotope composition inferred for sinking particulate Ba using simple mass balance models of Ba in the overlying water column and is hypothesized to reflect the removal of Ba from the upper water column with an associated isotopic fractionation of Δ diss-part 138/134Ba ≈ + 0.4 to +0.5. Perturbations to upper ocean Ba cycling, due to changes in export production and the supply of Ba via upwelling, should therefore be recorded by the isotope compositions of sedimentary authigenic Ba. Such insights will help to improve the reliable application of Ba accumulation rates in marine sediments as a proxy for past changes in export production.

Equilibrium fractionation of H and O isotopes in water from path integral molecular dynamics

NASA Astrophysics Data System (ADS)

Pinilla, Carlos; Blanchard, Marc; Balan, Etienne; Ferlat, Guillaume; Vuilleumier, Rodolphe; Mauri, Francesco

2014-06-01

The equilibrium fractionation factor between two phases is of importance for the understanding of many planetary and environmental processes. Although thermodynamic equilibrium can be achieved between minerals at high temperature, many natural processes involve reactions between liquids or aqueous solutions and solids. For crystals, the fractionation factor α can be theoretically determined using a statistical thermodynamic approach based on the vibrational properties of the phases. These calculations are mostly performed in the harmonic approximation, using empirical or ab-initio force fields. In the case of aperiodic and dynamic systems such as liquids or solutions, similar calculations can be done using finite-size molecular clusters or snapshots obtained from molecular dynamics (MD) runs. It is however difficult to assess the effect of these approximate models on the isotopic fractionation properties. In this work we present a systematic study of the calculation of the D/H and 18O/16O equilibrium fractionation factors in water for the liquid/vapour and ice/vapour phases using several levels of theory within the simulations. Namely, we use a thermodynamic integration approach based on Path Integral MD calculations (PIMD) and an empirical potential model of water. Compared with standard MD, PIMD takes into account quantum effects in the thermodynamic modeling of systems and the exact fractionation factor for a given potential can be obtained. We compare these exact results with those of modeling strategies usually used, which involve the mapping of the quantum system on its harmonic counterpart. The results show the importance of including configurational disorder for the estimation of isotope fractionation in liquid phases. In addition, the convergence of the fractionation factor as a function of parameters such as the size of the simulated system and multiple isotope substitution is analyzed, showing that isotope fractionation is essentially a local effect in

Competency-Based Education: What Is the Issue and Why Does It Matter? Policy Snapshot

ERIC Educational Resources Information Center

Anderson, Lexi

2017-01-01

The increasing need for highly-skilled employees in the workplace has policymakers and higher education leaders focused on innovative ways for students to access postsecondary education. These access points can include online programs, prior learning assessments and, the subject of this snapshot, competency-based education. The National Center for…

Isotope effect of mercury diffusion in air

PubMed Central

Koster van Groos, Paul G.; Esser, Bradley K.; Williams, Ross W.; Hunt, James R.

2014-01-01

Identifying and reducing impacts from mercury sources in the environment remains a considerable challenge and requires process based models to quantify mercury stocks and flows. The stable isotope composition of mercury in environmental samples can help address this challenge by serving as a tracer of specific sources and processes. Mercury isotope variations are small and result only from isotope fractionation during transport, equilibrium, and transformation processes. Because these processes occur in both industrial and environmental settings, knowledge of their associated isotope effects is required to interpret mercury isotope data. To improve the mechanistic modeling of mercury isotope effects during gas phase diffusion, an experimental program tested the applicability of kinetic gas theory. Gas-phase elemental mercury diffusion through small bore needles from finite sources demonstrated mass dependent diffusivities leading to isotope fractionation described by a Rayleigh distillation model. The measured relative atomic diffusivities among mercury isotopes in air are large and in agreement with kinetic gas theory. Mercury diffusion in air offers a reasonable explanation of recent field results reported in the literature. PMID:24364380

Isotope effect of mercury diffusion in air.

PubMed

Koster van Groos, Paul G; Esser, Bradley K; Williams, Ross W; Hunt, James R

2014-01-01

Identifying and reducing impacts from mercury sources in the environment remains a considerable challenge and requires process based models to quantify mercury stocks and flows. The stable isotope composition of mercury in environmental samples can help address this challenge by serving as a tracer of specific sources and processes. Mercury isotope variations are small and result only from isotope fractionation during transport, equilibrium, and transformation processes. Because these processes occur in both industrial and environmental settings, knowledge of their associated isotope effects is required to interpret mercury isotope data. To improve the mechanistic modeling of mercury isotope effects during gas phase diffusion, an experimental program tested the applicability of kinetic gas theory. Gas-phase elemental mercury diffusion through small bore needles from finite sources demonstrated mass dependent diffusivities leading to isotope fractionation described by a Rayleigh distillation model. The measured relative atomic diffusivities among mercury isotopes in air are large and in agreement with kinetic gas theory. Mercury diffusion in air offers a reasonable explanation of recent field results reported in the literature.

Heterogeneous distribution of Zn stable isotopes in mice and applications to medical sciences

NASA Astrophysics Data System (ADS)

Moynier, F.; Fujii, T.; Shaw, A.; Le Borgne, M.

2013-12-01

Zinc is required for the function of more than 300 enzymes involved in many metabolic pathways, and is a vital micronutrient for living organisms. To investigate if Zn isotopes could be used to better understand metal homeostasis, as well as a biomarker for diseases, we assessed the distribution of natural Zn isotopes in various mouse tissues. We found that, with respect to Zn isotopes, most mouse organs are isotopically distinct and that the total range of variation within one mouse encompasses the variations observed in the Earth's crust. Therefore, biological activity must have a major impact on the distribution of Zn isotopes in inorganic materials. The most striking aspect of the data is that red blood cells and bones are enriched by ~0.5 per mil in 66Zn relative to 64Zn when compared to serum, and up to ~1 per mil when compared to the brain and liver. This fractionation is well explained by the equilibrium distribution of isotopes between different bonding environments of Zn in different organs. Differences in gender and genetic background did not appear to affect the isotopic distribution of Zn. Together, these results suggest that potential use of Zn isotopes as a tracer for dietary Zn, and for detecting disturbances in Zn metabolism due to pathological conditions.

The Nation's Report Card Reading 2011 State Snapshot Report. Oregon. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2011 State Snapshot Report. Oregon. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. Oregon. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Mathematics 2011 State Snapshot Report. Oregon. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Reading 2011 State Snapshot Report. Minnesota. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. Minnesota. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. Minnesota. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Reading 2011 State Snapshot Report. Minnesota. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2011 State Snapshot Report. Hawaii. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2009 State Snapshot Report. Hawaii. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. Hawaii. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Reading 2009 State Snapshot Report. Hawaii. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The Nation's Report Card Reading 2011 State Snapshot Report. Hawaii. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. Hawaii. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2009 State Snapshot Report. Idaho. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. Idaho. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Reading 2009 State Snapshot Report. Idaho. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The Nation's Report Card Reading 2011 State Snapshot Report. Idaho. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2011 State Snapshot Report. Idaho. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. Idaho. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Mathematics 2013 State Snapshot Report. Tennessee. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Tennessee's 2013 student achievement in…

The Nation's Report Card Mathematics 2013 State Snapshot Report. Michigan. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Michigan's 2013 student achievement in…

The Nation's Report Card Reading 2013 State Snapshot Report. Massachusetts. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Massachusetts' 2013 student achievement in…

The Nation's Report Card Mathematics 2013 State Snapshot Report. Connecticut. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Connecticut's 2013 student achievement in…

The Nation's Report Card Reading 2013 State Snapshot Report. Idaho. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Idaho's 2013 student achievement in reading…

The Nation's Report Card Mathematics 2013 State Snapshot Report. Massachusetts. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Massachusetts' 2013 student achievement in…

The Nation's Report Card Mathematics 2013 State Snapshot Report. Illinois. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Illinois's 2013 student achievement in…

The Nation's Report Card Reading 2009 State Snapshot Report. Massachusetts. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Massachusetts' student achievement in reading. In…

The Nation's Report Card Reading 2009 State Snapshot Report. Connecticut. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Connecticut's student achievement in reading. In…

The Nation's Report Card Mathematics 2009 State Snapshot Report. Idaho. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Idaho's student achievement in mathematics. In…

The Nation's Report Card Mathematics 2009 State Snapshot Report. Iowa. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Iowa's student achievement in mathematics. In…

The Nation's Report Card Mathematics 2009 State Snapshot Report. Connecticut. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Connecticut's student achievement in mathematics.…

The Nation's Report Card Mathematics 2009 State Snapshot Report. Illinois. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Illinois' student achievement in mathematics. In…

The Nation's Report Card Mathematics 2009 State Snapshot Report. Florida. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Florida's student achievement in mathematics. In…

The Nation's Report Card Mathematics 2009 State Snapshot Report. Arkansas. Grade 12 Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Arkansas' student achievement in mathematics. In…

Safety of stable isotope use.

PubMed

Koletzko, B; Sauerwald, T; Demmelmair, H

1997-08-01

The increased employment of stable isotope tracers for diagnostic and research purposes frequently raises questions on potential risks associated with their use, which is of particular importance in the paediatric age group. Biological effects and the potential of adverse events has been evaluated in a large number of animal and, in part, also human studies. Possible differences in physical, chemical and biochemical behaviour resulting in kinetic and thermodynamic isotope effects between stable isotopes of the same element are related to the relative differences in atomic weight. Deuterium (2H), which differs markedly in mass from the predominant hydrogen isotope 1H, may induce serious side-effects at high concentrations in body fluids. The threshold dose for the occurrence of side-effects lies well above the usual tracer dosages for clinical use. In contrast to deuterium, heavier stable isotopes such as 13C, 15N or 18O that differ relatively little in mass from the predominant isotopes such as 12C, does not show any adverse biological effects even at highest enrichments. The doses of stable isotope tracer substances that are used for clinical diagnostic and research purposes appear safe and without any adverse effects. Stable isotope tracers should only be used in children if the trace is safe at the doses applied, and tracer is chemically pure and stable. In the case of intravenous application, the tracer preparation must also be sterile and pyrogen free.

Isotopic effects on phonon anharmonicity in layered van der Waals crystals: Isotopically pure hexagonal boron nitride

NASA Astrophysics Data System (ADS)

Cuscó, Ramon; Artús, Luis; Edgar, James H.; Liu, Song; Cassabois, Guillaume; Gil, Bernard

2018-04-01

Hexagonal boron nitride (h -BN) is a layered crystal that is attracting a great deal of attention as a promising material for nanophotonic applications. The strong optical anisotropy of this crystal is key to exploit polaritonic modes for manipulating light-matter interactions in 2D materials. h -BN has also great potential for solid-state neutron detection and neutron imaging devices, given the exceptionally high thermal neutron capture cross section of the boron-10 isotope. A good knowledge of phonons in layered crystals is essential for harnessing long-lived phonon-polariton modes for nanophotonic applications and may prove valuable for developing solid-state 10BN neutron detectors with improved device architectures and higher detection efficiencies. Although phonons in graphene and isoelectronic materials with a similar hexagonal layer structure have been studied, the effect of isotopic substitution on the phonons of such lamellar compounds has not been addressed yet. Here we present a Raman scattering study of the in-plane high-energy Raman active mode on isotopically enriched single-crystal h -BN. Phonon frequency and lifetime are measured in the 80-600-K temperature range for 10B-enriched, 11B-enriched, and natural composition high quality crystals. Their temperature dependence is explained in the light of perturbation theory calculations of the phonon self-energy. The effects of crystal anisotropy, isotopic disorder, and anharmonic phonon-decay channels are investigated in detail. The isotopic-induced changes in the phonon density of states are shown to enhance three-phonon anharmonic decay channels in 10B-enriched crystals, opening the possibility of isotope tuning of the anharmonic phonon decay processes.

Application of LA-MC-ICP-MS for analysis of Sr isotope ratios in speleothems

NASA Astrophysics Data System (ADS)

Weber, Michael; Scholz, Denis; Wassenburg, Jasper A.; Jochum, Klaus Peter; Breitenbach, Sebastian

2017-04-01

Speleothems are well established climate archives. In order to reconstruct past climate variability, several geochemical proxies, such as δ13C and δ18O as well as trace elements are available. Since several factors influence each individual proxy, robust interpretation is often hampered. This calls for multi-proxy approaches involving additional isotope systems that can help to delineate the role of different sources of water within the epikarst and changes in soil composition. Sr isotope ratios (87Sr/86Sr) have been shown to provide useful information about water residence time and water mixing in the host rock. Furthermore, Sr isotopes are not fractionated during calcite precipitation, implying that the 87Sr/86Sr ratio of the speleothem provides a direct record of the drip water. While most speleothem studies applying Sr isotopes used the TIMS methodology, LA-MC-ICP-MS has been utilized for several other archives, such as otoliths and teeth. This method provides the advantage of faster data acquisition, higher spatial resolution, larger sample throughput and the absence of chemical treatment prior to analysis. Here we present the first LA-MC-ICP-MS Sr isotope data for speleothems. The analytical uncertainty of our LA-MC-ICP-MS Sr data is in a similar range as for other carbonate materials. The results of different ablation techniques (i.e. line scan and spots) are reproducible within error, implying that the application of this technique on speleothems is possible. In addition, several comparative measurements of different carbonate reference materials (i.e. MACS-3, JCt-1, JCp-1), such as tests with standard bracketing and comparison of the 87Sr/86Sr ratios with nanosecond laser ablation system and a state-of-the-art femtosecond laser ablation system, show the robustness of the method. We applied the method to samples from Morocco (Grotte de Piste) and India (Mawmluh Cave). Our results show only very small changes in the 87Sr/86Sr ratios of both speleothems

Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation

NASA Astrophysics Data System (ADS)

Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

2016-01-01

Light isotopes separation, such as 3He/4He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as 3He/4He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high 3He/4He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application.

Forensic Stable Isotope Biogeochemistry

NASA Astrophysics Data System (ADS)

Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

2016-06-01

Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

The Nation's Report Card Reading 2013 State Snapshot Report. Tennessee. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Tennessee's 2013 student achievement in reading.…

The Nation's Report Card Reading 2013 State Snapshot Report. Michigan. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Michigan's 2013 student achievement in reading. In…

The Nation's Report Card Mathematics 2013 State Snapshot Report. Iowa. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Iowa's 2013 student achievement in mathematics. In…

The Nation's Report Card Reading 2013 State Snapshot Report. Arkansas. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Arkansas' 2013 student achievement in reading. In…

The Nation's Report Card Reading 2013 State Snapshot Report. Florida. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Florida's 2013 student achievement in reading. In…

The Nation's Report Card Mathematics 2013 State Snapshot Report. Florida. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Florida's 2013 student achievement in mathematics.…

The Nation's Report Card Mathematics 2013 State Snapshot Report. Arkansas. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Arkansas' 2013 student achievement in mathematics.…

The Nation's Report Card Reading 2013 State Snapshot Report. Connecticut. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Connecticut's 2013 student achievement in reading.…

The Nation's Report Card Mathematics 2013 State Snapshot Report. Idaho. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Idaho's 2013 student achievement in mathematics.…

The Nation's Report Card Reading 2013 State Snapshot Report. Illinois. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Illinois' 2013 student achievement in reading. In…

The Nation's Report Card Reading 2013 State Snapshot Report. Iowa. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Iowa's 2013 student achievement in reading. In…

The Nation's Report Card Reading 2009 State Snapshot Report. Iowa. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Iowa's student achievement in reading. In 2009,…

The Nation's Report Card Reading 2009 State Snapshot Report. Arkansas. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Arkansas' student achievement in reading. In 2009,…

The Nation's Report Card Reading 2009 State Snapshot Report. Illinois. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Illinois' student achievement in reading. In 2009,…

The Nation's Report Card Reading 2009 State Snapshot Report. Florida. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Florida's student achievement in reading. In 2009,…

The Nation's Report Card Reading 2009 State Snapshot Report. Idaho. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Idaho's student achievement in reading. In 2009,…

Radiogenic Isotopes in Weathering and Hydrology

NASA Astrophysics Data System (ADS)

Blum, J. D.; Erel, Y.

2003-12-01

There are a small group of elements that display variations in their isotopic composition, resulting from radioactive decay within minerals over geological timescales. These isotopic variations provide natural fingerprints of rock-water interactions and have been widely utilized in studies of weathering and hydrology. The isotopic systems that have been applied in such studies are dictated by the limited number of radioactive parent-daughter nuclide pairs with half-lives and isotopic abundances that result in measurable differences in daughter isotope ratios among common rocks and minerals. Prior to their application to studies of weathering and hydrology, each of these isotopic systems was utilized in geochronology and petrology. As in the case of their original introduction into geochronology and petrology, isotopic systems with the highest concentrations of daughter isotopes in common rocks and minerals and systems with the largest observed isotopic variations were introduced first and have made the largest impact on our understanding of weathering and hydrologic processes. Although radiogenic isotopes have helped elucidate many important aspects of weathering and hydrology, it is important to note that in almost every case that will be discussed in this chapter, our fundamental understanding of these topics came from studies of variations in the concentrations of major cations and anions. This chapter is a "tools chapter" and thus it will highlight applications of radiogenic isotopes that have added additional insight into a wide spectrum of research areas that are summarized in almost all of the other chapters of this volume.The first applications of radiogenic isotopes to weathering processes were based on studies that sought to understand the effects of chemical weathering on the geochronology of whole-rock samples and geochronologically important minerals (Goldich and Gast, 1966; Dasch, 1969; Blaxland, 1974; Clauer, 1979, 1981; Clauer et al., 1982); as well

Light stable isotope analysis of meteorites by ion microprobe

NASA Technical Reports Server (NTRS)

Mcsween, Harry Y., Jr.

1994-01-01

The main goal was to develop the necessary secondary ion mass spectrometer (SIMS) techniques to use a Cameca ims-4f ion microprobe to measure light stable isotope ratios (H, C, O and S) in situ and in non-conducting mineral phases. The intended application of these techniques was the analysis of meteorite samples, although the techniques that have been developed are equally applicable to the investigation of terrestrial samples. The first year established techniques for the analysis of O isotope ratios (delta O-18 and delta O-17) in conducting mineral phases and the measurement of S isotope ratios (delta S-34) in a variety of sulphide phases. In addition, a technique was developed to measure delta S-34 values in sulphates, which are insulators. Other research undertaken in the first year resulted in SIMS techniques for the measurement of wide variety of trace elements in carbonate minerals, with the aim of understanding the nature of alteration fluids in carbonaceous chondrites. In the second year we developed techniques for analyzing O isotope ratios in nonconducting mineral phases. These methods are potentially applicable to the measurement of other light stable isotopes such as H, C and S in insulators. Also, we have further explored the analytical techniques used for the analysis of S isotopes in sulphides by analyzing troilite in a number of L and H ordinary chondrites. This was done to see if there was any systematic differences with petrological type.

Using Internet Snapshot Surveys to Enhance Our Understanding of the Availability of the Novel Psychoactive Substance Alpha-methyltryptamine (AMT).

PubMed

Wood, David Michael; Dargan, Paul Ivor

2013-07-02

Alpha-methyltryptamine (AMT) is a novel psychoactive substance available over the Internet. This study used European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) Internet snapshot methodology to investigate the availability and cost of AMT in March/October 2012. From March to October 2012, there was a decrease in the number of Internet sites selling AMT (44 to 31). AMT powder was cheaper in "bulk" (100 g) than in "recreational-user" (100 mg) quantities, and there was a decrease in price. Data from Internet snapshot surveys complement and allow triangulation of data from other sources to build a more detailed picture on availability and use of novel psychoactive substances.

Surface area dependence of calcium isotopic reequilibration in carbonates: Implications for isotopic signatures in the weathering zone

NASA Astrophysics Data System (ADS)

Fernandez, N. M.; Druhan, J. L.; Potrel, A.; Jacobson, A. D.

2016-12-01

The concept of dynamic equilibrium carries the implicit assumption of continued isotopic exchange between a mineral and the surrounding fluid. While this effect has received much attention in the marine paleoproxy literature, it has been relatively overlooked in application to the terrestrial environment. In weathering systems, a potential consequence is that rapid reequilibration may alter or erase isotopic signatures generated during secondary mineral formation. The extent and timescale over which isotopic signatures are reset in these hydrologic systems is unknown. Using reactive transport modeling, we show isotopic reequilibration under conditions reflecting terrestrial hydrologic settings to be significant and dependent on the reactive surface area of the solid. In particular, we suggest that the non-traditional stable isotopes commonly used in application to carbonates (e.g., Ca, Mg, Sr) are sensitive to these effects due to their rapid reaction rates. We aim to characterize the dependence of Ca isotopic reequilibration on surface area during calcite precipitation via batch experiments conducted at ambient temperature over 48-hour time periods. Calcite precipitation was performed in a closed batch reactor utilizing a controlled free-drift method. The batch reactors contained mixed supersaturated solutions of CaCl2 and NaHCO3 at an initial pH of 8.54. Precipitation was initiated by seed inoculation of calcite crystals with two distinct, pre-constrained surface areas. All experiments achieved the same final state of chemical equilibrium, but as expected, the fastest approach to equilibrium occurred for experiments employing calcite seeds with the highest surface area. This implies that differences in equilibrated Ca isotope ratios (δ44/40Ca) should reflect differences in surface area. This prediction is upheld by models of the experiments, indicating a measureable difference in δ44Ca during calcite precipitation where the higher surface area corresponds to

Reactive transport modeling of Li isotope fractionation

NASA Astrophysics Data System (ADS)

Wanner, C.; Sonnenthal, E. L.

2013-12-01

The fractionation of Li isotopes has been used as a proxy for interaction processes between silicate rocks and any kind of fluids. In particular, Li isotope measurements are powerful because Li is almost exclusively found in silicate minerals. Moreover, the two stable Li isotopes, 6Li and 7Li, differ by 17% in mass introducing a large mass dependent isotope fractionation even at high temperature. Typical applications include Li isotope measurements along soil profiles and of river waters to track silicate weathering patterns and Li isotope measurements of geothermal wells and springs to assess water-rock interaction processes in geothermal systems. For this contribution we present a novel reactive transport modeling approach for the simulation of Li isotope fractionation using the code TOUGHREACT [1]. It is based on a 6Li-7Li solid solution approach similar to the one recently described for simulating Cr isotope fractionation [2]. Model applications include the simulation of granite weathering along a 1D flow path as well as the simulation of a column experiment related to an enhanced geothermal system. Results show that measured δ7Li values are mainly controlled by (i) the degree of interaction between Li bearing primary silicate mineral phases (e.g., micas, feldspars) and the corresponding fluid, (ii) the Li isotope fractionation factor during precipitation of secondary mineral phases (e.g., clays), (iii) the Li concentration in primary and secondary Li bearing mineral phases and (iv) the proportion of dissolved Li that adsorbs to negatively charged surfaces (e.g., clays, Fe/Al-hydroxides). To date, most of these parameters are not very well constrained. Reactive transport modeling thus currently has to rely on many assumptions. Nevertheless, such models are powerful because they are the only viable option if individual contributions of all potential processes on the resulting (i.e., measured) Li isotopic ratio have to be quantitatively assessed. Accordingly, we

Regulatory Snapshots: integrative mining of regulatory modules from expression time series and regulatory networks.

PubMed

Gonçalves, Joana P; Aires, Ricardo S; Francisco, Alexandre P; Madeira, Sara C

2012-01-01

Explaining regulatory mechanisms is crucial to understand complex cellular responses leading to system perturbations. Some strategies reverse engineer regulatory interactions from experimental data, while others identify functional regulatory units (modules) under the assumption that biological systems yield a modular organization. Most modular studies focus on network structure and static properties, ignoring that gene regulation is largely driven by stimulus-response behavior. Expression time series are key to gain insight into dynamics, but have been insufficiently explored by current methods, which often (1) apply generic algorithms unsuited for expression analysis over time, due to inability to maintain the chronology of events or incorporate time dependency; (2) ignore local patterns, abundant in most interesting cases of transcriptional activity; (3) neglect physical binding or lack automatic association of regulators, focusing mainly on expression patterns; or (4) limit the discovery to a predefined number of modules. We propose Regulatory Snapshots, an integrative mining approach to identify regulatory modules over time by combining transcriptional control with response, while overcoming the above challenges. Temporal biclustering is first used to reveal transcriptional modules composed of genes showing coherent expression profiles over time. Personalized ranking is then applied to prioritize prominent regulators targeting the modules at each time point using a network of documented regulatory associations and the expression data. Custom graphics are finally depicted to expose the regulatory activity in a module at consecutive time points (snapshots). Regulatory Snapshots successfully unraveled modules underlying yeast response to heat shock and human epithelial-to-mesenchymal transition, based on regulations documented in the YEASTRACT and JASPAR databases, respectively, and available expression data. Regulatory players involved in functionally enriched

Regulatory Snapshots: Integrative Mining of Regulatory Modules from Expression Time Series and Regulatory Networks

PubMed Central

Gonçalves, Joana P.; Aires, Ricardo S.; Francisco, Alexandre P.; Madeira, Sara C.

2012-01-01

Explaining regulatory mechanisms is crucial to understand complex cellular responses leading to system perturbations. Some strategies reverse engineer regulatory interactions from experimental data, while others identify functional regulatory units (modules) under the assumption that biological systems yield a modular organization. Most modular studies focus on network structure and static properties, ignoring that gene regulation is largely driven by stimulus-response behavior. Expression time series are key to gain insight into dynamics, but have been insufficiently explored by current methods, which often (1) apply generic algorithms unsuited for expression analysis over time, due to inability to maintain the chronology of events or incorporate time dependency; (2) ignore local patterns, abundant in most interesting cases of transcriptional activity; (3) neglect physical binding or lack automatic association of regulators, focusing mainly on expression patterns; or (4) limit the discovery to a predefined number of modules. We propose Regulatory Snapshots, an integrative mining approach to identify regulatory modules over time by combining transcriptional control with response, while overcoming the above challenges. Temporal biclustering is first used to reveal transcriptional modules composed of genes showing coherent expression profiles over time. Personalized ranking is then applied to prioritize prominent regulators targeting the modules at each time point using a network of documented regulatory associations and the expression data. Custom graphics are finally depicted to expose the regulatory activity in a module at consecutive time points (snapshots). Regulatory Snapshots successfully unraveled modules underlying yeast response to heat shock and human epithelial-to-mesenchymal transition, based on regulations documented in the YEASTRACT and JASPAR databases, respectively, and available expression data. Regulatory players involved in functionally enriched

Stable Isotope Applications for Understanding Shark Ecology in the Northeast Pacific Ocean.

PubMed

Reum, Jonathan C P; Williams, Gregory D; Harvey, Chris J

Stable isotopes are used to address a wide range of ecological questions and can help researchers and managers better understand the movement and trophic ecology of sharks. Here, we review how shark studies from the Northeast Pacific Ocean (NEP) have employed stable isotopes to estimate trophic level and diet composition and infer movement and habitat-use patterns. To date, the number of NEP shark studies that have used stable isotopes is limited, suggesting that the approach is underutilized. To aid shark researchers in understanding the strengths and limitations of the approach, we provide a brief overview of carbon and nitrogen stable isotope trophic discrimination properties (e.g., change in δ 15 N between predator and prey), tissue sample preparation methods specific to elasmobranchs, and methodological considerations for the estimation of trophic level and diet composition. We suggest that stable isotopes are a potentially powerful tool for addressing basic questions about shark ecology and are perhaps most valuable when combined and analysed with other data types (e.g., stomach contents, tagging data, or other intrinsic biogeochemical markers). © 2017 Elsevier Ltd. All rights reserved.

Perspectives on land snails - sampling strategies for isotopic analyses

NASA Astrophysics Data System (ADS)

Kwiecien, Ola; Kalinowski, Annika; Kamp, Jessica; Pellmann, Anna

2017-04-01

Since the seminal works of Goodfriend (1992), several substantial studies confirmed a relation between the isotopic composition of land snail shells (d18O, d13C) and environmental parameters like precipitation amount, moisture source, temperature and vegetation type. This relation, however, is not straightforward and site dependent. The choice of sampling strategy (discrete or bulk sampling) and cleaning procedure (several methods can be used, but comparison of their effects in an individual shell has yet not been achieved) further complicate the shell analysis. The advantage of using snail shells as environmental archive lies in the snails' limited mobility, and therefore an intrinsic aptitude of recording local and site-specific conditions. Also, snail shells are often found at dated archaeological sites. An obvious drawback is that shell assemblages rarely make up a continuous record, and a single shell is only a snapshot of the environmental setting at a given time. Shells from archaeological sites might represent a dietary component and cooking would presumably alter the isotopic signature of aragonite material. Consequently, a proper sampling strategy is of great importance and should be adjusted to the scientific question. Here, we compare and contrast different sampling approaches using modern shells collected in Morocco, Spain and Germany. The bulk shell approach (fine-ground material) yields information on mean environmental parameters within the life span of analyzed individuals. However, despite homogenization, replicate measurements of bulk shell material returned results with a variability greater than analytical precision (up to 2‰ for d18O, and up to 1‰ for d13C), calling for caution analyzing only single individuals. Horizontal high-resolution sampling (single drill holes along growth lines) provides insights into the amplitude of seasonal variability, while vertical high-resolution sampling (multiple drill holes along the same growth line

Precise and accurate isotope ratio measurements by ICP-MS.

PubMed

Becker, J S; Dietze, H J

2000-09-01

The precise and accurate determination of isotope ratios by inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) is important for quite different application fields (e.g. for isotope ratio measurements of stable isotopes in nature, especially for the investigation of isotope variation in nature or age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, quality assurance of fuel material, for reprocessing plants, nuclear material accounting and radioactive waste control, for tracer experiments using stable isotopes or long-lived radionuclides in biological or medical studies). Thermal ionization mass spectrometry (TIMS), which used to be the dominant analytical technique for precise isotope ratio measurements, is being increasingly replaced for isotope ratio measurements by ICP-MS due to its excellent sensitivity, precision and good accuracy. Instrumental progress in ICP-MS was achieved by the introduction of the collision cell interface in order to dissociate many disturbing argon-based molecular ions, thermalize the ions and neutralize the disturbing argon ions of plasma gas (Ar+). The application of the collision cell in ICP-QMS results in a higher ion transmission, improved sensitivity and better precision of isotope ratio measurements compared to quadrupole ICP-MS without the collision cell [e.g., for 235U/238U approximately 1 (10 microg x L(-1) uranium) 0.07% relative standard deviation (RSD) vs. 0.2% RSD in short-term measurements (n = 5)]. A significant instrumental improvement for ICP-MS is the multicollector device (MC-ICP-MS) in order to obtain a better precision of isotope ratio measurements (with a precision of up to 0.002%, RSD). CE- and HPLC-ICP-MS are used for the separation of isobaric interferences of long-lived radionuclides and stable isotopes by determination of spallation nuclide abundances in an irradiated tantalum target.

Why we need a centralized repository for isotopic data

USDA-ARS?s Scientific Manuscript database

Stable isotopes encode the origin and integrate the history of matter; thus, their analysis offers tremendous potential to address questions across diverse scientific disciplines. Indeed, the broad applicability of stable isotopes, coupled with advancements in high-throughput analysis, have created ...

A Snapshot of Young Children's Mathematical Competencies: Results from the Longitudinal Study of Australian Children

ERIC Educational Resources Information Center

MacDonald, Amy; Carmichael, Colin

2015-01-01

This article presents a snapshot of the mathematical competencies of children aged four to five years in Australian early childhood education settings, as perceived by their educators. Data are presented from a nationally-representative sample of 6511 children participating in the Longitudinal Study of Australian Children (LSAC). The results…

Metal stable isotopes in low-temperature systems: A primer

USGS Publications Warehouse

Bullen, T.D.; Eisenhauer, A.

2009-01-01

Recent advances in mass spectrometry have allowed isotope scientists to precisely determine stable isotope variations in the metallic elements. Biologically infl uenced and truly inorganic isotope fractionation processes have been demonstrated over the mass range of metals. This Elements issue provides an overview of the application of metal stable isotopes to low-temperature systems, which extend across the borders of several science disciplines: geology, hydrology, biology, environmental science, and biomedicine. Information on instrumentation, fractionation processes, data-reporting terminology, and reference materials presented here will help the reader to better understand this rapidly evolving field.

Ammonium transport and reaction in contaminated groundwater: Application of isotope tracers and isotope fractionation studies

USGS Publications Warehouse

Böhlke, J.K.; Smith, Richard L.; Miller, Daniel N.

2006-01-01

Ammonium (NH4+) is a major constituent of many contaminated groundwaters, but its movement through aquifers is complex and poorly documented. In this study, processes affecting NH4+ movement in a treated wastewater plume were studied by a combination of techniques including large‐scale monitoring of NH4+ distribution; isotopic analyses of coexisting aqueous NH4+, NO3−, N2, and sorbed NH4+; and in situ natural gradient 15NH4+tracer tests with numerical simulations of 15NH4+, 15NO3−, and 15N2 breakthrough data. Combined results indicate that the main mass of NH4+ was moving downgradient at a rate about 0.25 times the groundwater velocity. Retardation factors and groundwater ages indicate that much of the NH4+ in the plume was recharged early in the history of the wastewater disposal. NO3− and excess N2 gas, which were related to each other by denitrification near the plume source, were moving downgradient more rapidly and were largely unrelated to coexisting NH4+. The δ15N data indicate areas of the plume affected by nitrification (substantial isotope fractionation) and sorption (no isotope fractionation). There was no conclusive evidence for NH4+‐consuming reactions (nitrification or anammox) in the anoxic core of the plume. Nitrification occurred along the upper boundary of the plume but was limited by a low rate of transverse dispersive mixing of wastewater NH4+ and O2 from overlying uncontaminated groundwater. Without induced vertical mixing or displacement of plume water with oxic groundwater from upgradient sources, the main mass of NH4+ could reach a discharge area without substantial reaction long after the more mobile wastewater constituents are gone. Multiple approaches including in situ isotopic tracers and fractionation studies provided critical information about processes affecting NH4+ movement and N speciation.

Future trends in transport and fate of diffuse contaminants in catchments, with special emphasis on stable isotope applications

USGS Publications Warehouse

Turner, J.; Albrechtsen, H.-J.; Bonell, M.; Duguet, J.-P.; Harris, B.; Meckenstock, R.; McGuire, K.; Moussa, R.; Peters, N.; Richnow, H.H.; Sherwood-Lollar, B.; Uhlenbrook, S.; van, Lanen H.

2006-01-01

A summary is provided of the first of a series of proposed Integrated Science Initiative workshops supported by the UNESCO International Hydrological Programme. The workshop brought together hydrologists, environmental chemists, microbiologists, stable isotope specialists and natural resource managers with the purpose of communicating new ideas on ways to assess microbial degradation processes and reactive transport at catchment scales. The focus was on diffuse contamination at catchment scales and the application of compound-specific isotope analysis (CSIA) in the assessment of biological degradation processes of agrochemicals. Major outcomes were identifying the linkage between water residence time distribution and rates of contaminant degradation, identifying the need for better information on compound specific microbial degradation isotope fractionation factors and the potential of CSIA in identifying key degradative processes. In the natural resource management context, a framework was developed where CSIA techniques were identified as practically unique in their capacity to serve as distributed integrating indicators of process across a range of scales (micro to diffuse) of relevance to the problem of diffuse pollution assessment. Copyright ?? 2006 John Wiley & Sons, Ltd.

ICC-CLASS: isotopically-coded cleavable crosslinking analysis software suite

PubMed Central

2010-01-01

Background Successful application of crosslinking combined with mass spectrometry for studying proteins and protein complexes requires specifically-designed crosslinking reagents, experimental techniques, and data analysis software. Using isotopically-coded ("heavy and light") versions of the crosslinker and cleavable crosslinking reagents is analytically advantageous for mass spectrometric applications and provides a "handle" that can be used to distinguish crosslinked peptides of different types, and to increase the confidence of the identification of the crosslinks. Results Here, we describe a program suite designed for the analysis of mass spectrometric data obtained with isotopically-coded cleavable crosslinkers. The suite contains three programs called: DX, DXDX, and DXMSMS. DX searches the mass spectra for the presence of ion signal doublets resulting from the light and heavy isotopic forms of the isotopically-coded crosslinking reagent used. DXDX searches for possible mass matches between cleaved and uncleaved isotopically-coded crosslinks based on the established chemistry of the cleavage reaction for a given crosslinking reagent. DXMSMS assigns the crosslinks to the known protein sequences, based on the isotopically-coded and un-coded MS/MS fragmentation data of uncleaved and cleaved peptide crosslinks. Conclusion The combination of these three programs, which are tailored to the analytical features of the specific isotopically-coded cleavable crosslinking reagents used, represents a powerful software tool for automated high-accuracy peptide crosslink identification. See: http://www.creativemolecules.com/CM_Software.htm PMID:20109223

Energy Transition Initiative: Island Energy Snapshot - Trinidad and Tobago; NREL (National Renewable Energy Laboratory)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2015-05-20

This profile provides a snapshot of the energy landscape of Trinidad and Tobago, a two-island nation located off the coast of Venezuela. Trinidad and Tobago’s electricity rates are some of the lowest in the Caribbean at approximately $0.04 per kilowatt-hour (kWh), well below the regional average of $0.33/kWh.

Isotopic Ratios of Samarium by TIMS for Nuclear Forensic Application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Louis Jean, James; Inglis, Jeremy David

The isotopic ratio of Nd, Sm, and Gd can provide important information regarding fissile material (nuclear devices, reactors), neutron environment, and device yield. These studies require precise measurement of Sm isotope ratios, by either TIMS or MC-ICP-MS. There has been an increasing trend to measure smaller and smaller quantities of Sm bearing samples. In nuclear forensics 10-100 ng of Sm are needed for precise measurement. To measure sub-ng Sm samples using TIMS for nuclear forensic analysis.

The Nation's Report Card Reading 2013 State Snapshot Report. New Hampshire. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for New Hampshire's 2013 student achievement in…

The Nation's Report Card Mathematics 2013 State Snapshot Report. New Hampshire. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for New Hampshire's 2013 student achievement in…

The Nation's Report Card Mathematics 2013 State Snapshot Report. New Jersey. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for New Jersey's 2013 student achievement in…

The Nation's Report Card Mathematics 2013 State Snapshot Report. South Dakota. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for South Dakota's 2013 student achievement in…

The Nation's Report Card Reading 2013 State Snapshot Report. South Dakota. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for South Dakota's 2013 student achievement in…

The Nation's Report Card Reading 2013 State Snapshot Report. West Virginia. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for West Virginia's 2013 student achievement in…

The Nation's Report Card Mathematics 2011 State Snapshot Report. West Virginia. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Reading 2011 State Snapshot Report. West Virginia. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2009 State Snapshot Report. West Virginia. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. West Virginia. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Reading 2009 State Snapshot Report. West Virginia. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The Nation's Report Card Reading 2011 State Snapshot Report. West Virginia. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2011 State Snapshot Report. New Hampshire. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2011 State Snapshot Report. New Hampshire. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. New Hampshire. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2009 State Snapshot Report. New Hampshire. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. New Hampshire. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Reading 2009 State Snapshot Report. New Hampshire. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The Nation's Report Card Mathematics 2013 State Snapshot Report. West Virginia. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for West Virginia's 2013 student achievement in…

The Nation's Report Card Mathematics 2009 State Snapshot Report. New Hampshire. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for New Hampshire's student achievement in…

The Nation's Report Card Reading 2011 State Snapshot Report. DoDEA. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. DoDEA. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Reading 2011 State Snapshot Report. DoDEA. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to other…

The Nation's Report Card Reading 2009 State Snapshot Report. DoDEA. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The Nation's Report Card Mathematics 2011 State Snapshot Report. DoDEA. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2011

2011-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2011 mathematics assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2011 to…

The Nation's Report Card Reading 2009 State Snapshot Report. DoDEA. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 reading assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. Overall results, achievement level percentages and average score results, comparison of the average score in 2009 to other…

The lead isotopic composition of dust in the vicinity of a uranium mine in northern Australia and its use for radiation dose assessment.

PubMed

Bollhöfer, Andreas; Honeybun, Russell; Rosman, Kevin; Martin, Paul

2006-08-01

Airborne lead isotope ratios were measured via Thermal Ionisation Mass Spectrometry in samples from the vicinity of Ranger uranium mine in northern Australia. Dust deposited on leaves of Acacia spp. was washed off and analysed to gain a geographical snapshot of lead isotope ratios in the region. Aerosols were also collected on Teflon filters that were changed monthly over one seasonal cycle using a low volume diaphragm pump. Lead isotope ratios in dust deposited on leaves overestimate the relative amount of mine origin airborne lead, most likely due to a difference of the size distribution of particles collected on leaves and true aerosol size distribution. Seasonal measurements show that the annual average mine contribution to airborne lead concentrations in Jabiru East, approximately 2.5 km northwest of the mine, amounted to 13%, with distinct differences between the wet and dry season. The relative contribution of mine origin lead deposited on leaves in the dry season drops to less than 1% at a distance of 12.5 km from the mine along the major wind direction. An approach is outlined, in which lead isotope ratios are used to estimate the effective radiation dose received from the inhalation of mine origin radioactivity trapped in or on dust. Using the data from our study, this dose has been calculated to be approximately 2 microSv year(-1) for people living and working in the area.

Ion microprobe measurement of strontium isotopes in calcium carbonate with application to salmon otoliths

USGS Publications Warehouse

Weber, P.K.; Bacon, C.R.; Hutcheon, I.D.; Ingram, B.L.; Wooden, J.L.

2005-01-01

The ion microprobe has the capability to generate high resolution, high precision isotopic measurements, but analysis of the isotopic composition of strontium, as measured by the 87Sr/ 86Sr ratio, has been hindered by isobaric interferences. Here we report the first high precision measurements of 87Sr/ 86Sr by ion microprobe in calcium carbonate samples with moderate Sr concentrations. We use the high mass resolving power (7000 to 9000 M.R.P.) of the SHRIMP-RG ion microprobe in combination with its high transmission to reduce the number of interfering species while maintaining sufficiently high count rates for precise isotopic measurements. The isobaric interferences are characterized by peak modeling and repeated analyses of standards. We demonstrate that by sample-standard bracketing, 87Sr/86Sr ratios can be measured in inorganic and biogenic carbonates with Sr concentrations between 400 and 1500 ppm with ???2??? external precision (2??) for a single analysis, and subpermil external precision with repeated analyses. Explicit correction for isobaric interferences (peak-stripping) is found to be less accurate and precise than sample-standard bracketing. Spatial resolution is ???25 ??m laterally and 2 ??m deep for a single analysis, consuming on the order of 2 ng of material. The method is tested on otoliths from salmon to demonstrate its accuracy and utility. In these growth-banded aragonitic structures, one-week temporal resolution can be achieved. The analytical method should be applicable to other calcium carbonate samples with similar Sr concentrations. Copyright ?? 2005 Elsevier Ltd.

Petrographic and C & O isotopic characteristics of the earliest stages of aqueous alteration of CM chondrites

NASA Astrophysics Data System (ADS)

Vacher, Lionel G.; Marrocchi, Yves; Villeneuve, Johan; Verdier-Paoletti, Maximilien J.; Gounelle, Matthieu

2017-09-01

CM chondrites form the largest group of hydrated meteorites and span a wide range of alteration states, with the Paris meteorite being the least altered CM described to date. Ca-Carbonates are powerful proxies for the alteration conditions of CMs because they are direct snapshots of the chemical and isotopic compositions of the parent fluids. Here, we report a petrographic and a C isotope and O isotope survey of Ca-carbonates in Paris in order to better characterize the earliest stages of aqueous alteration. Petrographic observations show that Paris contains two distinct populations of Ca-carbonates: Type 1a Ca-carbonates, which are surrounded by rims of tochilinite/cronstedtite intergrowths (TCIs), and new Type 0 Ca-carbonates, which do not exhibit the TCI rims. The TCI rims of Type 1a Ca-carbonates commonly outline euhedral crystal faces, demonstrating that these Ca-carbonates were (i) partially or totally pseudomorphosed by TCI and (ii) precipitated at the earliest stages of aqueous alteration, before Type 0 Ca-carbonates. Isotopic measurements show that Paris' Ca-carbonates have δ13C values that range from 19 to 80‰ (PDB), δ18O values that range from 29 to 41%, and δ17O values that range from 13 to 24‰ (SMOW). According to the δ13C-δ18O values of Paris' Ca-carbonates, we developed a new alteration model that involves (i) the equilibration of a primordial 17,18O-rich water (PW) with 16O-rich anhydrous silicates and (ii) varying contribution of 12C- and 13C-rich soluble organic matter (SOMs). It also suggests that many parameters control the C and O isotopic composition of Ca-carbonates, the principles being the degree of isotopic equilibration between the PW and the anhydrous silicates, the respective contribution of 12C and 13C-rich SOMs as well as the thermal evolution of CM parent bodies. Consequently, we suggest that CM Ca-carbonates could record both positive and negative δ13C-δ18O relationships, but a systematic correspondence is probably absent

The isotopic effects of electron transfer: an explanation for Fe isotope fractionation in nature

NASA Astrophysics Data System (ADS)

Kavner, A.; Shahar, A.; Bonet, F.; Simon, J. I.; Young, E.

2004-12-01

Recent developments in mass spectrometry techniques have created opportunities to examine the partitioning behavior of stable isotopes of transition metals with a focus on application to iron isotopes. Iron oxidizing and reducing bacteria have been shown to cause isotope fractionations similar in magnitude to those observed in sedimentary environments and it is believed that biological activity is responsible for the most significant Fe isotope fractionation in natural settings. Debate over the use of Fe isotopes as a biological marker resulted from subsequent measurements of fractionations in a variety of abiotic systems. The accumulated evidence, in both biotic and abiotic systems, points to a connection between redox processes and Fe isotope fractionation, however the exact mechanism for isotope fractionation is not yet well understood. Here, we present both a newly-developed theory based on chemical kinetics and preliminary experimental results that quantitatively delineate the relationship between driving force in a charge transfer reaction and resulting Fe isotope fractionation. The theory, based on R. Marcus's chemical kinetics theory for electron transfer (Ann. Rev. Phys. Chem. 15 (1964), 155), predicts that fractionation increases linearly with driving force with a proportionality related to two factors: the difference between isotopic equilibrium exchange of products and reactants, and the reorganization energy along the reaction coordinate. The theoretical predictions were confirmed by measurements of isotopic fractionation associated with electroplating iron metal from a ferrous chloride solution. Isotope fractionation of Fe electroplated under potentiostatic conditions was measured as a function of applied electrochemical potential. As plating voltage was varied from -50 mV to -2.0 V, the isotopic signature of the electroplated iron became depleted in heavy Fe, with δ 56Fe values ranging from -0.106(±0.01) to -2.290(±±0.006)‰ , and corresponding

Isotopic composition of atmospheric moisture from pan water evaporation measurements.

PubMed

Devi, Pooja; Jain, Ashok Kumar; Rao, M Someshwer; Kumar, Bhishm

2015-01-01

A continuous and reliable time series data of the stable isotopic composition of atmospheric moisture is an important requirement for the wider applicability of isotope mass balance methods in atmospheric and water balance studies. This requires routine sampling of atmospheric moisture by an appropriate technique and analysis of moisture for its isotopic composition. We have, therefore, used a much simpler method based on an isotope mass balance approach to derive the isotopic composition of atmospheric moisture using a class-A drying evaporation pan. We have carried out the study by collecting water samples from a class-A drying evaporation pan and also by collecting atmospheric moisture using the cryogenic trap method at the National Institute of Hydrology, Roorkee, India, during a pre-monsoon period. We compared the isotopic composition of atmospheric moisture obtained by using the class-A drying evaporation pan method with the cryogenic trap method. The results obtained from the evaporation pan water compare well with the cryogenic based method. Thus, the study establishes a cost-effective means of maintaining time series data of the isotopic composition of atmospheric moisture at meteorological observatories. The conclusions drawn in the present study are based on experiments conducted at Roorkee, India, and may be examined at other regions for its general applicability.

Isotopic niches support the resource breadth hypothesis

USGS Publications Warehouse

Rader, Jonathan A.; Newsome, Seth D.; Sabat, Pablo; Chesser, R. Terry; Dillon, Michael E.; Martinez del Rio, Carlos

2017-01-01

Because a broad spectrum of resource use allows species to persist in a wide range of habitat types, and thus permits them to occupy large geographical areas, and because broadly distributed species have access to more diverse resource bases, the resource breadth hypothesis posits that the diversity of resources used by organisms should be positively related with the extent of their geographic ranges.We investigated isotopic niche width in a small radiation of South American birds in the genus Cinclodes. We analysed feathers of 12 species of Cinclodes to test the isotopic version of the resource breadth hypothesis and to examine the correlation between isotopic niche breadth and morphology.We found a positive correlation between the widths of hydrogen and oxygen isotopic niches (which estimate breadth of elevational range) and widths of the carbon and nitrogen isotopic niches (which estimates the diversity of resources consumed, and hence of habitats used). We also found a positive correlation between broad isotopic niches and wing morphology.Our study not only supports the resource breadth hypothesis but it also highlights the usefulness of stable isotope analyses as tools in the exploration of ecological niches. It is an example of a macroecological application of stable isotopes. It also illustrates the importance of scientific collections in ecological studies.

Stable isotope views on ecosystem function: challenging or challenged?

PubMed

Resco, Víctor; Querejeta, José I; Ogle, Kiona; Voltas, Jordi; Sebastià, Maria-Teresa; Serrano-Ortiz, Penélope; Linares, Juan C; Moreno-Gutiérrez, Cristina; Herrero, Asier; Carreira, José A; Torres-Cañabate, Patricia; Valladares, Fernando

2010-06-23

Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Ubeda, 18-22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes.

Successful application of lead isotopes in source apportionment, legal proceedings, remediation and monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gulson, Brian, E-mail: brian.gulson@mq.edu.au; CSIRO Earth Science and Resource Engineering North Ryde, NSW 1670; Korsch, Michael

In late 2006, the seaside community in Esperance Western Australia was alerted to thousands of native bird species dying. The source of the lead (Pb) was determined by Pb isotopes to derive from the handling of Pb carbonate concentrate through the Port, which began in July 2005. Concern was expressed for the impact of this on the community. Our objectives were to employ Pb isotope ratios to evaluate the source of Pb in environmental samples for use in legal proceedings, and for use in remediation and monitoring. Isotope measurements were undertaken of bird livers, plants, drinking water, soil, harbour sediments,more » air, bulk ceiling dust, gutter sludge, surface swabs and blood. The unique lead isotopic signature of the contaminating Pb carbonate enabled diagnostic apportionment of lead in samples. Apart from some soil and water samples, the proportion of contaminating Pb was >95% in the environmental samples. Lead isotopes were critical in resolving legal proceedings, are being used in the remediation of premises, were used in monitoring of workers involved in the decontamination of the storage facility, and monitoring transport of the concentrate through another port facility. Air samples show the continued presence of contaminant Pb, more than one year after shipping of concentrate ceased, probably arising from dust resuspension. Brief details of the comprehensive testing and cleanup of the Esperance community are provided along with the role of the Community. Lead isotopic analyses can provide significant benefits to regulatory agencies, interested parties, and the community where the signature is able to be characterised with a high degree of certainty. - Highlights: Black-Right-Pointing-Triangle Lead carbonate concentrate. Black-Right-Pointing-Triangle Successful use of Pb isotopes in identifying sources of Pb arising from transport and shipping. Black-Right-Pointing-Triangle Use of Pb isotopes in legal proceedings and their use in cleanup of residences

The Nation's Report Card Reading 2013 State Snapshot Report. New Jersey. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2014

2014-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2013 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for New Jersey's 2013 student achievement in reading.…

The Nation's Report Card Reading 2009 State Snapshot Report. West Virginia. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for West Virginia's student achievement in reading. In…

The Nation's Report Card Mathematics 2009 State Snapshot Report. West Virginia. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for West Virginia's student achievement in reading. In…

The Nation's Report Card Reading 2009 State Snapshot Report. New Hampshire. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for New Hampshire's student achievement in reading. In…

The Nation's Report Card Mathematics 2009 State Snapshot Report. South Dakota. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This paper presents the results for South Dakota's student achievement in mathematics.…

The Nation's Report Card Mathematics 2009 State Snapshot Report. New Jersey. Grade 12, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each state and jurisdiction that participated in the National Assessment of Educational Progress (NAEP) 2009 Grade 12 Reading and Mathematics State Pilot assessment receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for New Jersey's student achievement in mathematics.…

All-diode-laser cooling of Sr+ isotope ions for analytical applications

NASA Astrophysics Data System (ADS)

Jung, Kyunghun; Yamamoto, Kazuhiro; Yamamoto, Yuta; Miyabe, Masabumi; Wakaida, Ikuo; Hasegawa, Shuichi

2017-06-01

Trapping and cooling of Sr+ isotope ions by an all-diode-laser system has been demonstrated in order to develop a novel mass spectrometric technique in combination with ion trap-laser cooling. First, we constructed external cavity diode lasers and associated stabilization apparatus for laser cooling of Sr+ ions. The transition frequencies confirmed by optogalvanic spectroscopy enabled successful cooling of 88Sr+ ions. An image of two trapped ions has been captured by CCD camera. Minor isotopes, 84Sr+ and 86Sr+, were also cooled and trapped. From an analysis of the observed spectra of a string crystal of each isotope, the isotope shifts of the cooling transition (5s 2S1/2 → 5p 2P1/2) of Sr+ ions were determined to be +371(8) MHz for Δν84-88 and +169(8) MHz for Δν86-88. In the case of the repumping transition (4d 2D3/2 → 5p 2P1/2), Δν84-88 and Δν86-88 were measured to be -833(6) and -400(5) MHz, respectively. These values are in good agreement with previously reported values.

IsoCor: correcting MS data in isotope labeling experiments.

PubMed

Millard, Pierre; Letisse, Fabien; Sokol, Serguei; Portais, Jean-Charles

2012-05-01

Mass spectrometry (MS) is widely used for isotopic labeling studies of metabolism and other biological processes. Quantitative applications-e.g. metabolic flux analysis-require tools to correct the raw MS data for the contribution of all naturally abundant isotopes. IsoCor is a software that allows such correction to be applied to any chemical species. Hence it can be used to exploit any isotopic tracer, from well-known ((13)C, (15)N, (18)O, etc) to unusual ((57)Fe, (77)Se, etc) isotopes. It also provides new features-e.g. correction for the isotopic purity of the tracer-to improve the accuracy of quantitative isotopic studies, and implements an efficient algorithm to process large datasets. Its user-friendly interface makes isotope labeling experiments more accessible to a wider biological community. IsoCor is distributed under OpenSource license at http://metasys.insa-toulouse.fr/software/isocor/

High precision tungsten isotope analysis using MC-ICP-MS and application for terrestrial samples

NASA Astrophysics Data System (ADS)

Suzuki, K.; Takamasa, A.

2017-12-01

Tungsten has five isotopes (M = 180, 182, 183, 184, 186), and 182W isotope is a rediogenic isotope produced by b-decay of 182Hf. Its half life is short (8.9 m.y.), and 182W isotope has been investigated to understand the early Earth geochemical evolution. Both Hf and W are highly refractory elements. As Hf is a lithophile and W is a siderophile elements, 182Hf-182W system could give constraints on metal-silicate (core-mantle) differentiation such as especially early Earth system because of its larege fractionation betwenn core-mantle and short half life. Improvement of analytical techniques of W isotope analyses leads to findings of W isotope anomaly (mostly positive) in old komatiites (2.4 - 3.8 Ga) and young volcanic rocks (12 Ma Ontong Java Plateau and 6 Ma Baffin Bay). In our study, high-precision W isotope ratio measurement with MC-ICP-MS (Thermo co. Ltd., NEPTUNE PLUS). We have measured W standard solution (SRM 3163) and obtained the isotopic compositions with an precision of ± 5ppm. However, the standard solution, which separated by cation or anion exchange resin, has systematical 183W/184W drift to -5ppm. These phenomena was also reported by Willbold et al. (2011). Therefore, we used the standard solution for correction of isotopic fractionation of samples which was processed by the same method as that of the samples. We will present the data of terrestrial samples obtained by the technique dveloped in this study.

STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS

EPA Science Inventory

Stable isotopes are increasingly being used as tracers in ecological studies. One application uses isotopic ratios to quantify the proportional contributions of multiple sources to a mixture. Examples include food sources for animals, water sources for plants, pollution sources...

Spinel-olivine-pryoxene equilibrium iron isotopic fractionation and applications to natural peridotites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roskosz, Mathieu; Sio, Corliss K. I.; Dauphas, Nicolas

2015-11-15

Eight spinel-group minerals were synthesized by a flux-growth method producing spinels with varying composition and Fe3+/Fe-tot ratios. The mean force constants of iron bonds in these minerals were determined by synchrotron nuclear resonant inelastic X-ray scattering (NRIXS) in order to determine the reduced isotopic partition function ratios (beta-factors) of these spinels. The mean force constants are strongly dependent on the Fe3+/Fe-tot of the spinel but are independent, or weakly dependent on other structural and compositional parameters. From our spectroscopic data, it is found that a single redox-dependent calibration line accounts for the effects of Fe3+/Fe-tot on the beta-factors of spinels.more » This calibration successfully describes the equilibrium Fe isotopes fractionation factors between spinels and silicates (olivine and pyroxenes). Our predictions are in excellent agreement with independent determinations for the equilibrium Fe isotopic fractionations for the magnetite- fayalite and the magnetite-hedenbergite couples. Our calibration applies to the entire range of Fe3+/Fe-tot ratios found in natural spinels and provides a basis for interpreting iron isotopic variations documented in mantle peridotites. Except for a few exceptions, most of the samples measured so far are in isotopic disequilibrium, reflecting metasomatism and partial melting processes.« less

Isotope shifts from collinear laser spectroscopy of doubly charged yttrium isotopes

NASA Astrophysics Data System (ADS)

Vormawah, L. J.; Vilén, M.; Beerwerth, R.; Campbell, P.; Cheal, B.; Dicker, A.; Eronen, T.; Fritzsche, S.; Geldhof, S.; Jokinen, A.; Kelly, S.; Moore, I. D.; Reponen, M.; Rinta-Antila, S.; Stock, S. O.; Voss, A.

2018-04-01

Collinear laser spectroscopy has been performed on doubly charged ions of radioactive yttrium in order to study the isotope shifts of the 294.6-nm 5 s 1/2 2S →5 p 1/2 2P line. The potential of such an alkali-metal-like transition to improve the reliability of atomic-field-shift and mass-shift factor calculations, and hence the extraction of nuclear mean-square radii, is discussed. Production of yttrium ion beams for such studies is available at the IGISOL IV Accelerator Laboratory, Jyväskylä, Finland. This newly recommissioned facility is described here in relation to the on-line study of accelerator-produced short-lived isotopes using collinear laser spectroscopy and application of the technique to doubly charged ions.

Isotope effects on the optical spectra of semiconductors

NASA Astrophysics Data System (ADS)

Cardona, Manuel; Thewalt, M. L. W.

2005-10-01

Since the end of the cold war, macroscopic amounts of separated stable isotopes of most elements have been available “off the shelf” at affordable prices. Using these materials, single crystals of many semiconductors have been grown and the dependence of their physical properties on isotopic composition has been investigated. The most conspicuous effects observed have to do with the dependence of phonon frequencies and linewidths on isotopic composition. These affect the electronic properties of solids through the mechanism of electron-phonon interaction, in particular, in the corresponding optical excitation spectra and energy gaps. This review contains a brief introduction to the history, availability, and characterization of stable isotopes, including their many applications in science and technology. It is followed by a concise discussion of the effects of isotopic composition on the vibrational spectra, including the influence of average isotopic masses and isotopic disorder on the phonons. The final sections deal with the effects of electron-phonon interaction on energy gaps, the concomitant effects on the luminescence spectra of free and bound excitons, with particular emphasis on silicon, and the effects of isotopic composition of the host material on the optical transitions between the bound states of hydrogenic impurities.

Identification of a Debris Cloud from the Nuclear Powered SNAPSHOT Satellite with Haystack Radar Measurements

NASA Technical Reports Server (NTRS)

Stokely, C.; Stansbery, E.

2006-01-01

Data from the MIT Lincoln Laboratory (MIT/LL) Long Range Imaging Radar (known as the Haystack radar) have been used in the past to examine families of objects from individual satellite breakups or families of orbiting objects that can be isolated in altitude and inclination. This is possible because for some time after a breakup, the debris cloud of particles can remain grouped together in similar orbit planes. This cloud will be visible to the radar, in fixed staring mode, for a short time twice each day, as the orbit plane moves through the field of view. There should be a unique three-dimensional pattern in observation time, range, and range rate which can identify the cloud. Eventually, through slightly differing precession rates of the right ascension of ascending node of the debris cloud, the observation time becomes distributed so that event identification becomes much more difficult. Analyses of the patterns in observation time, range, and range rate have identified good debris candidates released from the polar orbiting SNAPSHOT satellite (International Identifier: 1965-027A). For orbits near 90o inclination, there is essentially no precession of the orbit plane. The SNAPSHOT satellite is a well known nuclear powered satellite launched in 1965 to a near circular 1300 km orbit with an inclination of 90.3o. This satellite began releasing debris in 1979 with new pieces being discovered and cataloged over the years. 51 objects are still being tracked by the United States Space Surveillance Network. An analysis of the Haystack data has identified at least 60 pieces of debris separate from the 51 known tracked debris pieces, where all but 2 of the 60 pieces have a size less than 10cm. The altitude and inclination (derived from range-rate with a circular orbit assumption) are consistent with the SNAPSHOT satellite and its tracked debris cloud.

Spatial and temporal skin blood volume and saturation estimation using a multispectral snapshot imaging camera

NASA Astrophysics Data System (ADS)

Ewerlöf, Maria; Larsson, Marcus; Salerud, E. Göran

2017-02-01

Hyperspectral imaging (HSI) can estimate the spatial distribution of skin blood oxygenation, using visible to near-infrared light. HSI oximeters often use a liquid-crystal tunable filter, an acousto-optic tunable filter or mechanically adjustable filter wheels, which has too long response/switching times to monitor tissue hemodynamics. This work aims to evaluate a multispectral snapshot imaging system to estimate skin blood volume and oxygen saturation with high temporal and spatial resolution. We use a snapshot imager, the xiSpec camera (MQ022HG-IM-SM4X4-VIS, XIMEA), having 16 wavelength-specific Fabry-Perot filters overlaid on the custom CMOS-chip. The spectral distribution of the bands is however substantially overlapping, which needs to be taken into account for an accurate analysis. An inverse Monte Carlo analysis is performed using a two-layered skin tissue model, defined by epidermal thickness, haemoglobin concentration and oxygen saturation, melanin concentration and spectrally dependent reduced-scattering coefficient, all parameters relevant for human skin. The analysis takes into account the spectral detector response of the xiSpec camera. At each spatial location in the field-of-view, we compare the simulated output to the detected diffusively backscattered spectra to find the best fit. The imager is evaluated for spatial and temporal variations during arterial and venous occlusion protocols applied to the forearm. Estimated blood volume changes and oxygenation maps at 512x272 pixels show values that are comparable to reference measurements performed in contact with the skin tissue. We conclude that the snapshot xiSpec camera, paired with an inverse Monte Carlo algorithm, permits us to use this sensor for spatial and temporal measurement of varying physiological parameters, such as skin tissue blood volume and oxygenation.

An Internet snapshot study to compare the international availability of the novel psychoactive substance methiopropamine.

PubMed

Vermette-Marcotte, A-E; Dargan, P I; Archer, J R H; Gosselin, S; Wood, D M

2014-08-01

With the increased use of novel psychoactive substances, there is an increasing availability of these substances from Internet-based suppliers. Methiopropamine, first reported in 2011, is a recreational drug available over the Internet. The aim of this study was to investigate availability and cost of methiopropamine in three different countries: the UK, France, and Canada. Using the European Monitoring Centre for Drugs and Drug Addiction Internet snapshot methodology, this study, conducted in June 2013, was undertaken in two different languages: in English (the UK and Canada) and in French (France and Canada), using three Internet searching engines: " google.co.uk ", " google.fr " and " google.ca ". A total of 62 sites were found, most of them were found from the English searches. 45% of the suppliers seemed to originate from the UK. The prices of methiopropamine were comparable between suppliers, no matter which search engine or language was used. The cost of a unit of methiopropamine was inversely related to the purchased quantity, going from 19.49 ± 0.15 GBP per gram for a purchase amount of 500 mg to 3.54 ± 0.13 GBP per gram for a purchase amount of 1 kg. The results of the present study demonstrate that the sale of methiopropamine has the potential to reach users across the world. It also appears to support that snapshot studies could be used for toxicovigilance across different countries, by studying the Internet market of novel psychoactive substances. To date, snapshot studies, used to monitor the Internet novel psychoactive substances market, have only been undertaken in Europe. We have shown that the flexibility of this methodology enables comparison of the online activity of drug sellers between different countries and continents and that, at least for methiopropamine, the UK is the predominant source for Internet supply.

Stable isotope views on ecosystem function: challenging or challenged?

PubMed Central

Resco, Víctor; Querejeta, José I.; Ogle, Kiona; Voltas, Jordi; Sebastià, Maria-Teresa; Serrano-Ortiz, Penélope; Linares, Juan C.; Moreno-Gutiérrez, Cristina; Herrero, Asier; Carreira, José A.; Torres-Cañabate, Patricia; Valladares, Fernando

2010-01-01

Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Úbeda, 18–22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes. PMID:20015858

What do the pictures say—snapshots of a career

PubMed Central

Cooper, Terrance G.

2017-01-01

Abstract What follows are snapshots of my career in chicken eyes, yeast and Rhodospirillum rubrum, castor beans, Escherichia coli and finally yeast again. In contrast, only a few of the failures that realistically make up a career are included. It is a tale of the generosity and influences of those who shaped what I am and what I learned in a wonderful profession. The science described is only that which I was lucky enough to do or was performed in my laboratory by those who really deserve the credit for any success that I’ve enjoyed. Not mentioned for lack of space are the critical contributions of many impressive investigators in the field of nitrogen-responsive regulation for no scientific investigation occurs in isolation. PMID:28582501

Isotopic niches support the resource breadth hypothesis.

PubMed

Rader, Jonathan A; Newsome, Seth D; Sabat, Pablo; Chesser, R Terry; Dillon, Michael E; Martínez Del Rio, Carlos

2017-03-01

Because a broad spectrum of resource use allows species to persist in a wide range of habitat types, and thus permits them to occupy large geographical areas, and because broadly distributed species have access to more diverse resource bases, the resource breadth hypothesis posits that the diversity of resources used by organisms should be positively related with the extent of their geographic ranges. We investigated isotopic niche width in a small radiation of South American birds in the genus Cinclodes. We analysed feathers of 12 species of Cinclodes to test the isotopic version of the resource breadth hypothesis and to examine the correlation between isotopic niche breadth and morphology. We found a positive correlation between the widths of hydrogen and oxygen isotopic niches (which estimate breadth of elevational range) and widths of the carbon and nitrogen isotopic niches (which estimates the diversity of resources consumed, and hence of habitats used). We also found a positive correlation between broad isotopic niches and wing morphology. Our study not only supports the resource breadth hypothesis but it also highlights the usefulness of stable isotope analyses as tools in the exploration of ecological niches. It is an example of a macroecological application of stable isotopes. It also illustrates the importance of scientific collections in ecological studies. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

SOURCE PARTITIONING USING STABLE ISOTOPES: COPING WITH TOO MANY SOURCES

EPA Science Inventory

Stable isotopes are increasingly being used as tracers in environmental studies. One application is to use isotopic ratios to quantitatively determine the proportional contribution of several sources to a mixture, such as the proportion of various pollution sources in a waste st...

USE OF STABLE ISOTOPES IN ENVIRONMENTAL AND FORENSIC GEOCHEMISTRY STUDIES

EPA Science Inventory

Stable carbon and hydrogen isotopes have been used for many decades in the petroleum industry, but the development of combined gas chromatography-isotope ratio mass spectrometry (GCIRMS) has led to a virtual explosion in application of this technique not only in petroleum explora...

Sulfur isotopic analysis of carbonyl sulfide and its application for biogeochemical cycles

NASA Astrophysics Data System (ADS)

Hattori, Shohei; Kamezaki, Kazuki; Ogawa, Takahiro; Toyoda, Sakae; Katayama, Yoko; Yoshida, Naohiro

2016-04-01

Carbonyl sulfide (OCS or COS) is the most abundant gas containing sulfur in the atmosphere, with an average mixing ratio of 500 p.p.t.v. in the troposphere. OCS is suggested as a sulfur source of the stratospheric sulfate aerosols (SSA) which plays an important role in Earth's radiation budget and ozone depletion. Therefore, OCS budget should be validated for prediction of climate change, but the global OCS budget is imbalance. Recently we developed a promising new analytical method for measuring the stable sulfur isotopic compositions of OCS using nanomole level samples: the direct isotopic analytical technique of on-line gas chromatography-isotope ratio mass spectrometry (GC-IRMS) using fragmentation ions S+ (Hattori et al., 2015). The first measurement of the δ34S value for atmospheric OCS coupled with isotopic fractionation for OCS sink reactions in the stratosphere (Hattori et al., 2011; Schmidt et al., 2012; Hattori et al., 2012) explains the reported δ34S value for background stratospheric sulfate, suggesting that OCS is a potentially important source for background (nonepisodic or nonvolcanic) stratospheric sulfate aerosols. This new method measuring δ34S values of OCS can be used to investigate OCS sources and sinks in the troposphere to better understand its cycle. It is known that some microorganisms in soil can degrade OCS, but the mechanism and the contribution to the OCS in the air are still uncertain. In order to determine sulfur isotopic enrichment factor of OCS during degradation via microorganisms, incubation experiments were conducted using strains belonging to the genera Mycobacterium, Williamsia and Cupriavidus, isolated from natural soil environments (Kato et al., 2008). As a result, sulfur isotope ratios of OCS were increased during degradation of OCS, indicating that reaction for OC32S is faster than that for OC33S and OC34S. OCS degradation via microorganisms is not mass-independent fractionation (MIF) process, suggesting that this

Low-temperature aqueous alteration on the CR chondrite parent body: Implications from in situ oxygen-isotope analyses

NASA Astrophysics Data System (ADS)

Jilly-Rehak, Christine E.; Huss, Gary R.; Nagashima, Kazu; Schrader, Devin L.

2018-02-01

The presence of hydrated minerals in chondrites indicates that water played an important role in the geologic evolution of the early Solar System; however, the process of aqueous alteration is still poorly understood. Renazzo-like carbonaceous (CR) chondrites are particularly well-suited for the study of aqueous alteration. Samples range from being nearly anhydrous to fully altered, essentially representing snapshots of the alteration process through time. We studied oxygen isotopes in secondary-minerals from six CR chondrites of varying hydration states to determine how aqueous fluid conditions (including composition and temperature) evolved on the parent body. Secondary minerals analyzed included calcite, dolomite, and magnetite. The O-isotope composition of calcites ranged from δ18O ≈ 9 to 35‰, dolomites from δ18O ≈ 23 to 27‰, and magnetites from δ18O ≈ -18 to 5‰. Calcite in less-altered samples showed more evidence of fluid evolution compared to heavily altered samples, likely reflecting lower water/rock ratios. Most magnetite plotted on a single trend, with the exception of grains from the extensively hydrated chondrite MIL 090292. The MIL 090292 magnetite diverges from this trend, possibly indicating an anomalous origin for the meteorite. If magnetite and calcite formed in equilibrium, then the relative 18O fractionation between them can be used to extract the temperature of co-precipitation. Isotopic fractionation in Al Rais carbonate-magnetite assemblages revealed low precipitation temperatures (∼60 °C). Assuming that the CR parent body experienced closed-system alteration, a similar exercise for parallel calcite and magnetite O-isotope arrays yields "global" alteration temperatures of ∼55 to 88 °C. These secondary mineral arrays indicate that the O-isotopic composition of the altering fluid evolved upon progressive alteration, beginning near the Al Rais water composition of Δ17O ∼ 1‰ and δ18O ∼ 10‰, and becoming increasingly

Application of isotope dilution technique in vitamin A nutrition.

PubMed

Wasantwisut, Emorn

2002-09-01

The isotope dilution technique involving deuterated retinol has been developed to quantitatively estimate total body reserves of vitamin A in humans. The technique provided good estimates in comparison to hepatic vitamin A concentrations in Bangladeshi surgical patients. Kinetic studies in the United States, Bangladesh, and Guatemala indicated the mean equilibration time of 17 to 20 days irrespective of the size of hepatic reserves. Due to the controversy surrounding the efficacy of a carotene-rich diet on improvement of vitamin A status, the isotope dilution technique was proposed to pursue this research question further (IAEA's coordinated research program). In the Philippines, schoolchildren with low serum retinol concentrations showed significant improvement in total body vitamin A stores following intake of carotene-rich foods (orange fruits and vegetables), using a three-day deuterated-retinol-dilution procedure. When Chinese kindergarten children were fed green and yellow vegetables during the winter, their total body vitamin A stores were sustained as compared to a steady decline of vitamin A stores in the control children. Likewise, daily consumption of purified beta-carotene or diet rich in provitamin A carotenoids were shown to prevent a loss in total body vitamin A stores among Thai lactating women during the rice-planting season. These studies demonstrate potentials of the isotope dilution technique to evaluate the impact of provitamin A carotenoid intervention programs.

Guideline on Isotope Dilution Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaffney, Amy

Isotope dilution mass spectrometry is used to determine the concentration of an element of interest in a bulk sample. It is a destructive analysis technique that is applicable to a wide range of analytes and bulk sample types. With this method, a known amount of a rare isotope, or ‘spike’, of the element of interest is added to a known amount of sample. The element of interest is chemically purified from the bulk sample, the isotope ratio of the spiked sample is measured by mass spectrometry, and the concentration of the element of interest is calculated from this result. Thismore » method is widely used, although a mass spectrometer required for this analysis may be fairly expensive.« less

A Snapshot Survey of AGNS/QSOS for Intergalactic Medium Studies

NASA Technical Reports Server (NTRS)

Sonneborn, George (Technical Monitor); Sembach, George

2005-01-01

This spectroscopic program with the Far Ultraviolet Spectroscopic Explorer (FUSE) program was designed to identify ultraviolet-bright active galactic nuclei (AGNs) and quasi-stellar objects (QSOs) for follow-up spectroscopy with FUSE and the Hubble Space Telescope (HST). All of the FUSE spectra obtained for this snapshot program (FUSE identifier D808) have been examined for data quality and flux levels. As expected, only a small number of objects observed (4/19) have flux levels suitable for follow-up spectroscopy. A portion of our effort in this program was devoted to comparing the spectra obtained in these snapshot exposures to others to determine if the spectra could be used for detailed scientific analyses. The resulting effort demonstrated that some of the brighter sources are relatively stable (non- variable), as determined through comparisons of the spectra at multiple epochs. For these brighter sources, the exposure times are simply too short to perform meaningful detailed analyses. Comparisons of the absorption lines in these spectra with those of higher signal-to-noise spectra, like those of PG1116+215 and H1821+643, showed that many of the lines of interest could not be characterized adequately at the S/N levels reached in the short snapshot exposures. As a result, the FUSE D808 observations are suitable only for their original purpose - flux determination. Several bright objects identified as part of this program include: HE0153-4520, flux >2x10E-14 erg cm^-2s^-1 at 1000 Angstroms IRASF04250-5718, flux >4x10E-14 erg cm^-2s^-1 A^-1 at 1000 Angstroms RXJ2154.1-4414, flux > 1.6x10E-14 erg cm^-2s^-1 A^-1 at 1000 Angstroms S50716+714, flux >2.5x10E-14 erg cm^-2s^-1 A^-1 at 1000 Angstroms. All of these objects have been incorporated into the primary target lists for the HST Cosmic Origins Spectrograph. Identifying such objects for follow-up observations with HST/COS was the primary goal of this program, so the program wa successful. In addition, some of the

Refined Use of Satellite Aerosol Optical Depth Snapshots to Constrain Biomass Burning Emissions in the GOCART Model

NASA Technical Reports Server (NTRS)

Petrenko, Mariya; Kahn, Ralph; Chin, Mian; Limbacher, James

2017-01-01

Simulations of biomass burning (BB) emissions in global chemistry and aerosol transport models depend on external inventories, which provide location and strength of burning aerosol sources. Our previous work (Petrenko et al., 2012) shows that satellite snapshots of aerosol optical depth (AOD) near the emitted smoke plume can be used to constrain model-simulated AOD, and effectively, the assumed source strength. We now refine the satellite-snapshot method and investigate applying simple multiplicative emission correction factors for the widely used Global Fire Emission Database version 3 (GFEDv3) emission inventory can achieve regional-scale consistency between MODIS AOD snapshots and the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. The model and satellite AOD are compared over a set of more than 900 BB cases observed by the MODIS instrument during the 2004, and 2006-2008 biomass burning seasons. The AOD comparison presented here shows that regional discrepancies between the model and satellite are diverse around the globe yet quite consistent within most ecosystems. Additional analysis of including small fire emission correction shows the complimentary nature of correcting for source strength and adding missing sources, and also indicates that in some regions other factors may be significant in explaining model-satellite discrepancies. This work sets the stage for a larger intercomparison within the Aerosol Inter-comparisons between Observations and Models (AeroCom) multi-model biomass burning experiment. We discuss here some of the other possible factors affecting the remaining discrepancies between model simulations and observations, but await comparisons with other AeroCom models to draw further conclusions.

Bayer Filter Snapshot Hyperspectral Fundus Camera for Human Retinal Imaging

PubMed Central

Liu, Wenzhong; Nesper, Peter; Park, Justin; Zhang, Hao F.; Fawzi, Amani A.

2016-01-01

Purpose To demonstrate the versatility and performance of a compact Bayer filter snapshot hyperspectral fundus camera for in-vivo clinical applications including retinal oximetry and macular pigment optical density measurements. Methods 12 healthy volunteers were recruited under an Institutional Review Board (IRB) approved protocol. Fundus images were taken with a custom hyperspectral camera with a spectral range of 460–630 nm. We determined retinal vascular oxygen saturation (sO2) for the healthy population using the captured spectra by least squares curve fitting. Additionally, macular pigment optical density was localized and visualized using multispectral reflectometry from selected wavelengths. Results We successfully determined the mean sO2 of arteries and veins of each subject (ages 21–80) with excellent intrasubject repeatability (1.4% standard deviation). The mean arterial sO2 for all subjects was 90.9% ± 2.5%, whereas the mean venous sO2 for all subjects was 64.5% ± 3.5%. The mean artery–vein (A–V) difference in sO2 varied between 20.5% and 31.9%. In addition, we were able to reveal and quantify macular pigment optical density. Conclusions We demonstrated a single imaging tool capable of oxygen saturation and macular pigment density measurements in vivo. The unique combination of broad spectral range, high spectral–spatial resolution, rapid and robust imaging capability, and compact design make this system a valuable tool for multifunction spectral imaging that can be easily performed in a clinic setting. PMID:27767345

Stable isotope dimethyl labelling for quantitative proteomics and beyond

PubMed Central

Hsu, Jue-Liang; Chen, Shu-Hui

2016-01-01

Stable-isotope reductive dimethylation, a cost-effective, simple, robust, reliable and easy-to- multiplex labelling method, is widely applied to quantitative proteomics using liquid chromatography-mass spectrometry. This review focuses on biological applications of stable-isotope dimethyl labelling for a large-scale comparative analysis of protein expression and post-translational modifications based on its unique properties of the labelling chemistry. Some other applications of the labelling method for sample preparation and mass spectrometry-based protein identification and characterization are also summarized. This article is part of the themed issue ‘Quantitative mass spectrometry’. PMID:27644970

Snapshots of the Universe: A Multilingual Astronomy Book

NASA Astrophysics Data System (ADS)

Beaton, R. L.; Sokal, K. R.; Liss, S. E.; Johnson, K. E.

2015-11-01

Dark Skies, Bright Kids! (DSBK) is an outreach organization at the University of Virginia, focused on enhancing elementary level science education in under-served communities. Early in the program, DSBK volunteers encountered difficulties connecting with English as a second language (ESL) students. To meet that challenge, DSBK volunteers created story-book style art with short descriptions of astronomical objects in both Spanish and English to help communicate basic astronomy concepts to these students. Building on this initial success, our simple project has evolved into a full multilingual children's book targeted at 2nd-5th grade students. Though originally in Spanish and English, a partnership with the University of Alberta (Canada) has produced a French translation of the text, broadening the outreach potential of the book. In this contribution, we describe Snapshots of the Universe (Instantáneas del Universo) and reflect upon the process of creating this unique resource.

Global Security, Medical Isotopes, and Nuclear Science

NASA Astrophysics Data System (ADS)

Ahle, Larry

2007-10-01

Over the past century basic nuclear science research has led to the use of radioactive isotopes into a wide variety of applications that touch our lives everyday. Some are obvious, such as isotopes for medical diagnostics and treatment. Others are less so, such as National/Global security issues. And some we take for granted, like the small amount of 241 Am that is in every smoke detector. At the beginning of this century, we are in a position where the prevalence and importance of some applications of nuclear science are pushing the basic nuclear science community for improved models and nuclear data. Yet, at the same time, the push by the basic nuclear science community to study nuclei that are farther and farther away from stability also offer new opportunities for many applications. This talk will look at several global security applications of nuclear science, summarizing current R&D and need for improved nuclear data It will also look at how applications of nuclear science, such as to medicine, will benefit from the push for more and more powerful radioactive ion beam facilities.

Forensic analysis of explosives using isotope ratio mass spectrometry (IRMS)--part 2: forensic inter-laboratory trial: bulk carbon and nitrogen stable isotopes in a range of chemical compounds (Australia and New Zealand).

PubMed

Benson, Sarah J; Lennard, Christopher J; Maynard, Philip; Hill, David M; Andrew, Anita S; Neal, Ken; Stuart-Williams, Hilary; Hope, Janet; Walker, G Stewart; Roux, Claude

2010-01-01

Comparability of data over time and between laboratories is a key issue for consideration in the development of global databases, and more broadly for quality assurance in general. One mechanism that can be utilized for evaluating traceability is an inter-laboratory trial. This paper addresses an inter-laboratory trial conducted across a number of Australian and New Zealand isotope ratio mass spectrometry (IRMS) laboratories. The main objective of this trial was to determine whether IRMS laboratories in these countries would record comparable values for the distributed samples. Four carbon containing and four nitrogen containing compounds were distributed to seven laboratories in Australia and one in New Zealand. The laboratories were requested to analyze the samples using their standard procedures. The data from each laboratory was evaluated collectively using International Standard ISO 13528 (Statistical methods for use in proficiency testing by inter-laboratory comparisons). "Warning signals" were raised against one participant in this trial. "Action signals" requiring corrective action were raised against four participants. These participants reviewed the data and possible sources for the discrepancies. This inter-laboratory trial was successful in providing an initial snapshot of the potential for traceability between the participating laboratories. The statistical methods described in this article could be used as a model for others needing to evaluate stable isotope results derived from multiple laboratories, e.g., inter-laboratory trials/proficiency testing. Ongoing trials will be conducted to improve traceability across the Australian and New Zealand IRMS community.

STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS (URUGUAY)

EPA Science Inventory

Stable isotopes are increasingly being used as tracers in ecological studies. One application uses isotopic ratios to quantify the proportional contributions of multiple sources to a mixture. Examples include pollution sources for air or water bodies, food sources for animals, ...

STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS (BRAZIL)

EPA Science Inventory

Stable isotopes are increasingly being used as tracers in ecological studies. One application uses isotopic ratios to quantify the proportional contributions of multiple sources to a mixture. Examples include pollution sources for air or water bodies, food sources for animals, ...

COMPOUND-SPECIFIC STABLE ISOTOPE ANALYSIS TO DEMONSTRATE IN-SITU MTBE BIOTRANSFORMATION

EPA Science Inventory

Change of stable isotope composition of organic contaminants (isotopic fractionation) is a useful indicator of biotransformation. Most of applications to date are in the area of chlorinated solvents and recently BTEX, MTBE and TBA. Chemical reactions (biotic- and abiotic transfor...

Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5

NASA Astrophysics Data System (ADS)

Ebeling, Harald

2017-08-01

Truly massive galaxy clusters play a pivotal role for a wealth of extragalactic and cosmological research topics, and SNAPshot observations of these systems are ideally suited to identify the most promising cluster targets for further, in-depth study. The power of this approach was demonstrated by ACS/WFC3 SNAPshots of X-ray selected MACS and eMACS clusters at z>0.3 obtained by us in previous Cycles (44 of them in all of F606W, F814W, F110W, and F140W). Based on these data, the CLASH MCT program selected 16 out of 25 of their targets to be MACS clusters. Similarly, all but one of the six most powerful cluster lenses selected for in-depth study by the HST Frontier Fields initiative are MACS detections, and so are 16 of the 29 z>0.3 clusters targeted by the RELICS legacy program.We propose to extend our spectacularly successful SNAPshot survey of the most X-ray luminous distant clusters to a redshift-mass regime that is poorly sampled by any other project. Targeting only extremely massive clusters at z>0.5 from the X-ray selected eMACS sample (median velocity dispersion: 1180 km/s), the proposed program will (a) identify the most powerful gravitational telescopes at yet higher redshift for the next generation of in-depth studies of the distant Universe with HST and JWST, (b) provide constraints on the mass distribution within these extreme systems, (c) help improve our understanding of the physical nature of galaxy-galaxy and galaxy-gas interactions in cluster cores, and (d) unveil Balmer Break Galaxies at z 2 and Lyman-break galaxies at z>6 as F814W dropouts.Acknowledging the broad community interest in our sample we waive our data rights for these observations.

The IRHUM (Isotopic Reconstruction of Human Migration) database - bioavailable strontium isotope ratios for geochemical fingerprinting in France

NASA Astrophysics Data System (ADS)

Willmes, M.; McMorrow, L.; Kinsley, L.; Armstrong, R.; Aubert, M.; Eggins, S.; Falguères, C.; Maureille, B.; Moffat, I.; Grün, R.

2013-11-01

Strontium isotope ratios (87Sr/86Sr) are a key geochemical tracer used in a wide range of fields including archaeology, ecology, food and forensic sciences. These applications are based on the principle that the Sr isotopic ratios of natural materials reflect the sources of strontium available during their formation. A major constraint for current studies is the lack of robust reference maps to evaluate the source of strontium isotope ratios measured in the samples. Here we provide a new dataset of bioavailable Sr isotope ratios for the major geologic units of France, based on plant and soil samples (Pangaea data repository doi:10.1594/PANGAEA.819142). The IRHUM (Isotopic Reconstruction of Human Migration) database is a web platform to access, explore and map our dataset. The database provides the spatial context and metadata for each sample, allowing the user to evaluate the suitability of the sample for their specific study. In addition, it allows users to upload and share their own datasets and data products, which will enhance collaboration across the different research fields. This article describes the sampling and analytical methods used to generate the dataset and how to use and access of the dataset through the IRHUM database. Any interpretation of the isotope dataset is outside the scope of this publication.

Oxygen isotope geochemistry of the amphiboles: isotope effects of cation substitutions in minerals

NASA Astrophysics Data System (ADS)

Kohn, Matthew J.; Valley, John W.

1998-06-01

The occurrence of coexisting amphiboles in rocks and the likelihood of concurrent isotope closure allows equilibrium oxygen isotope fractionations among the amphiboles to be recovered from natural samples. Oxygen isotope analyses of mineral separates using laser fluorination show that coexisting amphiboles increasingly partition 18O in the order: hornblende ≪ gedrite < cummingtonite ≤ anthophyllite. The observed fractionations at ˜575°C are: Δ(Ged-Hbl) = 0.8‰, Δ(Cum-Hbl) = 0.9, Δ(Cum-Ged) = 0.2, Δ(Ath-Ged) = 0.3, and Δ(Ath-Hbl) > 0.9. Previously published data for hornblende, actinolite, glaucophane, and garnet show that Δ(Act-Hbl) ˜ 0.2, Δ(Gln-Grt) ≫ 1, and Δ(Hbl-Grt) ˜ 0. Thus, glaucophane strongly partitions 18O relative to the calcic amphiboles. The fractionation between two amphiboles of arbitrary composition can be predicted from the known fractionations for mica endmembers, pyroxene endmembers, and exchange components such as CaAl(NaSi) -1, NaAl(CaMg) -1, CaMg -1, MgFe -1, FeMn -1, KNa -1, KAl( Si) -1, and Fe 3+Al -1. Applications of the exchange component method reproduce measured amphibole fractionations to within ±0.1 to ±0.2‰, whereas other predictive methods cause misfit for typical metamorphic hornblende of ≥0.5‰ at 575°C. Although the isotope effects of cation exchanges may be small at high-T, they magnify dramatically for minerals formed in surficial, diagenetic, and low-T metamorphic environments. Different composition clays are predicted to have equilibrium δ 18O differences of 2-9‰. If the isotope fractionation can be determined for one mineral endmember, then calibrated exchanges allow accurate prediction of the isotope fractionations for intermediate compositions of most ortho-, ring-, chain-, and sheet-silicates.

Stable isotope tracers and exercise physiology: past, present and future.

PubMed

Wilkinson, Daniel J; Brook, Matthew S; Smith, Kenneth; Atherton, Philip J

2017-05-01

Stable isotope tracers have been invaluable assets in physiological research for over 80 years. The application of substrate-specific stable isotope tracers has permitted exquisite insight into amino acid, fatty-acid and carbohydrate metabolic regulation (i.e. incorporation, flux, and oxidation, in a tissue-specific and whole-body fashion) in health, disease and response to acute and chronic exercise. Yet, despite many breakthroughs, there are limitations to 'substrate-specific' stable isotope tracers, which limit physiological insight, e.g. the need for intravenous infusions and restriction to short-term studies (hours) in controlled laboratory settings. In recent years significant interest has developed in alternative stable isotope tracer techniques that overcome these limitations, in particular deuterium oxide (D 2 O or heavy water). The unique properties of this tracer mean that through oral administration, the turnover and flux through a number of different substrates (muscle proteins, lipids, glucose, DNA (satellite cells)) can be monitored simultaneously and flexibly (hours/weeks/months) without the need for restrictive experimental control. This makes it uniquely suited for the study of 'real world' human exercise physiology (amongst many other applications). Moreover, using D 2 O permits evaluation of turnover of plasma and muscle proteins (e.g. dynamic proteomics) in addition to metabolomics (e.g. fluxomics) to seek molecular underpinnings, e.g. of exercise adaptation. Here, we provide insight into the role of stable isotope tracers, from substrate-specific to novel D 2 O approaches, in facilitating our understanding of metabolism. Further novel potential applications of stable isotope tracers are also discussed in the context of integration with the snowballing field of 'omic' technologies. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

A novel methodology to investigate isotopic biosignatures

NASA Astrophysics Data System (ADS)

Horner, T. J.; Lee, R. B. Y.; Henderson, G. M.; Rickaby, R. E. M.

2012-04-01

. coli (e.g. membranes, cytosol, etc.), including the catalytic metal atoms within CdCA. These experiments allow isotopic exchange reactions to be observed in biological systems at an unparalleled resolution, demonstrating that isotopic fractionation can occur, in vivo, on length scales as small as a few Å. We will explore future applications of this technique using the marine geochemistry of Cd as a case study. This experimental approach has great promise for studying the individual isotopic biosignatures of other biochemical reactions, in particular those which may have been active during early Earth History.

Isotopic Dependence of GCR Fluence behind Shielding

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.; Wilson, John W.; Saganti, Premkumar; Kim, Myung-Hee Y.; Cleghorn, Timothy; Zeitlin, Cary; Tripathi, Ram K.

2006-01-01

In this paper we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR), nuclear fragmentation cross-sections, and isotopic-grid on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. For the nuclear interaction data-base and transport solution, we use the quantum multiple-scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, respectively. The QMSFRG model is shown to accurately describe existing fragmentation data including proper description of the odd-even effects as function of the iso-spin dependence on the projectile nucleus. The principle finding of this study is that large errors (+/-100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotopic-grid (approx.170 ions) to ones that use a reduced isotopic-grid, for example the 59 ion-grid used in the HZETRN code in the past, however less significant errors (<+/-20%) occur in the elemental-fluence spectra. Because a complete isotopic-grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies.

Paleoproxies: Heavy Stable Isotope Perspectives

NASA Astrophysics Data System (ADS)

Nagler, T. F.; Hippler, D.; Siebert, C.; Kramers, J. D.

2002-12-01

potential to solve this problem for a given set of samples and thus to model the ocean system more accurately in different scales. Besides all complications some important applications of heavy stable isotopes as paleoproxies already emerge. Pilot studies indicate that Mo isotopes may present a proxy for the extend of anoxic condition in past oceans. On a finer scale the same system appears to provide a measure of (bio)-chemical redox-changes related to diagenesis. The Ca isotope system may complement more classical sea surface temperature proxies in particular environments. Promising results exist for polar waters (N. pachy left), as well as indications on the seasonality under global greenhouse conditions ~110-50 Ma ago. However, the heavily species dependent Ca isotope fractionation can not be interpreted by just adopting concepts and findings from the oxygen system. While a complication to the ease of use as SST proxy, this species dependence offers pathways to unravel different modes of bio-calcifications. Given the complexity of the matter, collaboration of specialists of different fields will be needed to develop successful process-related hypotheses and diagnostic tools.

Measurement of isotope ratios on transient signals by MC-ICP-MS.

PubMed

Günther-Leopold, Ines; Wernli, Beat; Kopajtic, Zlatko; Günther, Detlef

2004-01-01

Precise and accurate isotope ratio measurements are an important task in many applications such as isotope-dilution mass spectrometry, bioavailability studies, or the determination of isotope variations in geological or nuclear samples. The technique of MC-ICP-MS has attracted much attention because it permits the precise measurement of isotope compositions for a wide range of elements combined with excellent detection limits due to high ionisation efficiencies. However, the results are based mainly on measurements using continuous sample introduction. In the present study the determination of isotope ratios on various transient signals with a time duration of 30 to 60 s has been achieved by coupling high-performance liquid chromatography to a multicollector inductively coupled plasma mass spectrometer. In order to investigate the origin of ratio drifts across the transient signals for this hyphenated technique, measurements with the same standard solutions were also carried out using a flow-injection device for sample introduction. As a result of this application it could be concluded that the main source of the bias in the measured isotope ratios is within the ICP-MS instead of fractionation effects on the chromatographic column material. Preliminary studies on short transient signals of gaseous samples (dry plasma) showed a reverse fractionation effect compared with wet plasma conditions (flow injection and HPLC).

Resetting of Mg isotopes between calcite and dolomite during burial metamorphism: Outlook of Mg isotopes as geothermometer and seawater proxy

NASA Astrophysics Data System (ADS)

Hu, Zhongya; Hu, Wenxuan; Wang, Xiaomin; Lu, Yizhou; Wang, Lichao; Liao, Zhiwei; Li, Weiqiang

2017-07-01

Magnesium isotopes are an emerging tool to study the geological processes recorded in carbonates. Calcite, due to its ubiquitous occurrence and the large Mg isotope fractionation associated with the mineral, has attracted great interests in applications of Mg isotope geochemistry. However, the fidelity of Mg isotopes in geological records of carbonate minerals (e.g., calcite and dolomite) against burial metamorphism remains poorly constrained. Here we report our investigation on the Mg isotope systematics of a dolomitized Middle Triassic Geshan carbonate section in eastern China. Magnesium isotope analysis was complemented by analyses of Sr-C-O isotopic compositions, major and trace element concentrations, and petrographic and mineralogical features. Multiple lines of evidence consistently indicated that post-depositional diagenesis of carbonate minerals occurred to the carbonate rocks. Magnesium isotope compositions of the carbonate rocks closely follow a mixing trend between a high δ26Mg dolomite end member and a low δ26Mg calcite end member, irrespective of sample positions in the section and calcite/dolomite ratio in the samples. By fitting the measured Mg isotope data using a two-end member mixing model, an inter-mineral Δ26Mgdolomite-calcite fractionation of 0.72‰ was obtained. Based on the experimentally derived Mg isotope fractionation factors for dolomite and calcite, a temperature of 150-190 °C was calculated to correspond to the 0.72‰ Δ26Mgdolomite-calcite fractionation. Such temperature range matches with the burial-thermal history of the local strata, making a successful case of Mg isotope geothermometry. Our results indicate that both calcite and dolomite had been re-equilibrated during burial metamorphism, and based on isotope mass balance of Mg, the system was buffered by dolomite in the section. Therefore, burial metamorphism may reset Mg isotope signature of calcite, and Mg isotope compositions in calcite should be dealt with caution in

Capturing Snapshots of APE1 Processing DNA Damage

PubMed Central

Freudenthal, Bret D.; Beard, William A.; Cuneo, Matthew J.; Dyrkheeva, Nadezhda S.; Wilson, Samuel H.

2015-01-01

DNA apurinic-apyrimidinic (AP) sites are prevalent non-coding threats to genomic stability and are processed by AP endonuclease 1 (APE1). APE1 incises the AP-site phosphodiester backbone, generating a DNA repair intermediate that is potentially cytotoxic. The molecular events of the incision reaction remain elusive due in part to limited structural information. We report multiple high-resolution human APE1:DNA structures that divulge novel features of the APE1 reaction, including the metal binding site, nucleophile, and arginine clamps that mediate product release. We also report APE1:DNA structures with a T:G mismatch 5′ to the AP-site, representing a clustered lesion occurring in methylated CpG dinucleotides. These reveal that APE1 molds the T:G mismatch into a unique Watson-Crick like geometry that distorts the active site reducing incision. These snapshots provide mechanistic clarity for APE1, while affording a rational framework to manipulate biological responses to DNA damage. PMID:26458045

Successful application of lead isotopes in source apportionment, legal proceedings, remediation and monitoring.

PubMed

Gulson, Brian; Korsch, Michael; Winchester, Wayne; Devenish, Matthew; Hobbs, Thad; Main, Cleve; Smith, Gerard; Rosman, Kevin; Howearth, Lynette; Burn-Nunes, Laurie; Seow, Jimmy; Oxford, Cameron; Yun, Gracie; Gillam, Lindsay; Crisp, Michelle

2012-01-01

In late 2006, the seaside community in Esperance Western Australia was alerted to thousands of native bird species dying. The source of the lead (Pb) was determined by Pb isotopes to derive from the handling of Pb carbonate concentrate through the Port, which began in July 2005. Concern was expressed for the impact of this on the community. Our objectives were to employ Pb isotope ratios to evaluate the source of Pb in environmental samples for use in legal proceedings, and for use in remediation and monitoring. Isotope measurements were undertaken of bird livers, plants, drinking water, soil, harbour sediments, air, bulk ceiling dust, gutter sludge, surface swabs and blood. The unique lead isotopic signature of the contaminating Pb carbonate enabled diagnostic apportionment of lead in samples. Apart from some soil and water samples, the proportion of contaminating Pb was >95% in the environmental samples. Lead isotopes were critical in resolving legal proceedings, are being used in the remediation of premises, were used in monitoring of workers involved in the decontamination of the storage facility, and monitoring transport of the concentrate through another port facility. Air samples show the continued presence of contaminant Pb, more than one year after shipping of concentrate ceased, probably arising from dust resuspension. Brief details of the comprehensive testing and cleanup of the Esperance community are provided along with the role of the Community. Lead isotopic analyses can provide significant benefits to regulatory agencies, interested parties, and the community where the signature is able to be characterised with a high degree of certainty. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

Isotopic Biogeochemistry

NASA Technical Reports Server (NTRS)

Hayes, J. M.

1985-01-01

An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

Multispectral Snapshot Imagers Onboard Small Satellite Formations for Multi-Angular Remote Sensing

NASA Technical Reports Server (NTRS)

Nag, Sreeja; Hewagama, Tilak; Georgiev, Georgi; Pasquale, Bert; Aslam, Shahid; Gatebe, Charles K.

2017-01-01

Multispectral snapshot imagers are capable of producing 2D spatial images with a single exposure at selected, numerous wavelengths using the same camera, therefore operate differently from push broom or whiskbroom imagers. They are payloads of choice in multi-angular, multi-spectral imaging missions that use small satellites flying in controlled formation, to retrieve Earth science measurements dependent on the targets Bidirectional Reflectance-Distribution Function (BRDF). Narrow fields of view are needed to capture images with moderate spatial resolution. This paper quantifies the dependencies of the imagers optical system, spectral elements and camera on the requirements of the formation mission and their impact on performance metrics such as spectral range, swath and signal to noise ratio (SNR). All variables and metrics have been generated from a comprehensive, payload design tool. The baseline optical parameters selected (diameter 7 cm, focal length 10.5 cm, pixel size 20 micron, field of view 1.15 deg) and snapshot imaging technologies are available. The spectral components shortlisted were waveguide spectrometers, acousto-optic tunable filters (AOTF), electronically actuated Fabry-Perot interferometers, and integral field spectrographs. Qualitative evaluation favored AOTFs because of their low weight, small size, and flight heritage. Quantitative analysis showed that waveguide spectrometers perform better in terms of achievable swath (10-90 km) and SNR (greater than 20) for 86 wavebands, but the data volume generated will need very high bandwidth communication to downlink. AOTFs meet the external data volume caps well as the minimum spectral (wavebands) and radiometric (SNR) requirements, therefore are found to be currently feasible in spite of lower swath and SNR.

On-line Differential Thermal Isotope Analysis: A New Method for Measuring Oxygen and Hydrogen Isotopes of Hydration Water in Minerals

NASA Astrophysics Data System (ADS)

Bauska, T.; Hodell, D. A.; Walters, G.

2016-12-01

Oxygen (16O,17O,18O) and hydrogen (H,D) isotopes of hydration water in minerals provide a rich source of information about the conditions under which hydrated minerals form on Earth and other planetary bodies (e.g. Mars). We have developed a new method for measuring different types of bonded water (e.g., molecular, hydroxyl) contained in hydrated minerals by coupling a thermal gravimeter (TG) and a cavity ringdown laser spectrometer (CRDS). The method involves step heating a mineral sample, precisely measuring the weight loss and enthalpy as the sample undergoes dehydration and dehydroxylation, whilst simultaneously determining the oxygen and hydrogen isotopes of the water vapor evolved from the mineral sample by cavity ring-down laser spectroscopy (CRDS). Nitrogen carrier gas is used to transfer the sample from the TG to the CRDS via a heated line and interface box. The interface includes the capability of (i) cryogenic trapping discrete types of water for samples containing small amounts of water; (ii) injecting small quantities of water of known isotopic value for calibration; and (iii) converting volatile organic compounds to nascent amounts of water using a catalyst. The CRDS continually measures water vapor concentration in the optical cavity and hydrogen and oxygen isotope ratios. Isotopic values are calculated by integrating the product of the water amount and its isotopic value for the separated peaks after correcting for background. Precision of the method was estimated by comparing isotope results of total water for gypsum measured by DTIA with our conventional method of extraction and analysis (Gázquez et al., 2015. Rapid Communications in Mass Spectrometry, 29, 1997-2006). Errors for the isotopic values of total hydration water vary between ±0.08 and ±0.34 ‰ for δ18O and between ±0.16 and ±0.86 ‰ for δD. We demonstrate the application of the DTIA method to a variety of hydrous minerals and mineraloids including gypsum, clays, and amorphous

What do the pictures say-snapshots of a career.

PubMed

Cooper, Terrance G

2017-06-01

What follows are snapshots of my career in chicken eyes, yeast and Rhodospirillum rubrum, castor beans, Escherichia coli and finally yeast again. In contrast, only a few of the failures that realistically make up a career are included. It is a tale of the generosity and influences of those who shaped what I am and what I learned in a wonderful profession. The science described is only that which I was lucky enough to do or was performed in my laboratory by those who really deserve the credit for any success that I've enjoyed. Not mentioned for lack of space are the critical contributions of many impressive investigators in the field of nitrogen-responsive regulation for no scientific investigation occurs in isolation. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Making Connections To Improve Education: A Snapshot of School-Based Education Investments in Seven Making-Connections Sites.

ERIC Educational Resources Information Center

Jehl, Jeanne

This report provides a snapshot of school improvement efforts during early 2002 in several cities involved in "Making Connections," a demonstration project based on the premise that children do well when families do well, and families do better when they live in supportive neighborhoods. The project emphasizes three kinds of connections:…

A Review of Activity Implementation in Out-of-School Time Programs. Out-of-School Time Evaluation Snapshot.

ERIC Educational Resources Information Center

Bouffard, Suzanne; Little, Priscilla M. D.

Noting that most evaluations of out-of-school (OST) programs have examined the programs as a whole without taking into account the specific activities offered, this issue of "Out-of-School Time Evaluation Snapshots" surveys the range of activities being implemented in OST settings across the country to better understand and promote…

Application of isotope dilution inductively coupled plasma mass spectrometry to the analysis of marine sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLaren, J.W.; Beauchemin, D.; Berman, S.S.

1987-02-15

Isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) has been applied to the determination of 11 trace elements (Cr, Ni, Zn, Sr, Mo, Cd, Sn, Sb, Tl, Pb, and U) in the marine sediment reference materials MESS-1 and BCSS-1. Accuracy and, especially, precision are better than those that can be easily achieved by other ICP-MS calibration strategies, as long as isotopic equilibration is achieved and the isotopes used for the ratio measurement are free of isobaric interferences by molecular species. The measurement of the isotope ratios on unspiked samples provides a sensitive diagnostic of such interferences.

The IRHUM (Isotopic Reconstruction of Human Migration) database - bioavailable strontium isotope ratios for geochemical fingerprinting in France

NASA Astrophysics Data System (ADS)

Willmes, M.; McMorrow, L.; Kinsley, L.; Armstrong, R.; Aubert, M.; Eggins, S.; Falguères, C.; Maureille, B.; Moffat, I.; Grün, R.

2014-03-01

Strontium isotope ratios (87Sr / 86Sr) are a key geochemical tracer used in a wide range of fields including archaeology, ecology, food and forensic sciences. These applications are based on the principle that the Sr isotopic ratios of natural materials reflect the sources of strontium available during their formation. A major constraint for current studies is the lack of robust reference maps to evaluate the source of strontium isotope ratios measured in the samples. Here we provide a new data set of bioavailable Sr isotope ratios for the major geologic units of France, based on plant and soil samples (Pangaea data repository doi:10.1594/PANGAEA.819142). The IRHUM (Isotopic Reconstruction of Human Migration) database is a web platform to access, explore and map our data set. The database provides the spatial context and metadata for each sample, allowing the user to evaluate the suitability of the sample for their specific study. In addition, it allows users to upload and share their own data sets and data products, which will enhance collaboration across the different research fields. This article describes the sampling and analytical methods used to generate the data set and how to use and access the data set through the IRHUM database. Any interpretation of the isotope data set is outside the scope of this publication.

Application of Fe Isotopes to the Search for Life and Habitable Planets

NASA Technical Reports Server (NTRS)

Johnson, Clark M.; Beard, Brian L.; Nealson, Kenneth L.

2001-01-01

The relatively new field of Fe isotope geochemistry can make important contributions to tracing the geochemical cycling of Fe, which bears on issues such as metabolic processing of Fe, surface redox conditions, and development of planetary atmospheres and biospheres. It appears that Fe isotope fractionation in nature and the lab spans about 4 per mil (%) in Fe-56/Fe-54, and although this range is small, our new analytical methods produce a precision of +/- 0.05% on sample sizes as small as 100 ng (10(exp -7) g); this now provides us with a sufficient "signal-to-noise" ratio to make this isotope system useful. We review our work in three areas: 1) the terrestrial and lunar rock record, 2) experiments on inorganic fractionation, and 3) experiments involving biological processing of Fe. Additional information is contained in the original extended abstract.

Chlorine Isotopes: As a Possible Tracer of Fluid/Bio-Activities on Mars and a Progress Report on Chlorine Isotope Analysis by TIMs

NASA Technical Reports Server (NTRS)

Nakamura, N.; Nyquist, L.E.; Reese, Y.; Shih, C-Y.; Numata, M.; Fujitani, T.; Okano, O.

2009-01-01

Significantly large mass fractionations between chlorine isotopes (Cl-35, Cl-37) have been reported for terrestrial materials including both geological samples and laboratory materials. Also, the chlorine isotopic composition can be used as a tracer for early solar system processes. Moreover, chlorine is ubiquitous on the Martian surface. Typical chlorine abundances in Gusev soils are approx.0.5 %. The global surface average chlorine abundance also is approx.0.5 %. Striking variations among outcrop rocks at Meridiani were reported with some chlorine abundances as high as approx.2%. Characterizing conditions under which chlorine isotopic fractionation may occur is clearly of interest to planetary science. Thus, we have initiated development of a chlorine isotopic analysis technique using TIMS at NASA-JSC. We present here a progress report on the current status of development at JSC and discuss the possible application of chlorine isotopic analysis to Martian meteorites in a search for fluid- and possibly biological activity on Mars.

Laser ablation inductively coupled plasma mass spectrometry for direct isotope ratio measurements on solid samples

NASA Astrophysics Data System (ADS)

Pickhardt, Carola; Dietze, Hans-Joachim; Becker, J. Sabine

2005-04-01

Isotope ratio measurements have been increasingly used in quite different application fields, e.g., for the investigation of isotope variation in nature, in geoscience (geochemistry and geochronology), in cosmochemistry and planetary science, in environmental science, e.g., in environmental monitoring, or by the application of the isotope dilution technique for quantification purposes using stable or radioactive high-enriched isotope tracers. Due to its high sensitivity, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is today a challenging mass spectrometric technique for the direct determination of precise and accurate isotope ratios in solid samples. In comparison to laser ablation quadrupole ICP-MS (LA-ICP-QMS), laser ablation coupled to a double-focusing sector field ICP-MS (LA-ICP-SFMS) with single ion detection offers a significant improvement of sensitivity at low mass resolution, whereby isotope ratios can be measured with a precision to 0.1% relative standard deviation (R.S.D.). In LA-ICP-SFMS, many disturbing isobaric interferences of analyte and molecular ions can be separated at the required mass resolution (e.g., 40Ar16O+ and 56Fe+ for iron isotope ratio measurements). The precision on isotope ratio measurements was improved by one order of magnitude via the simultaneous detection of mass-separated ion currents of isotopes using multiple ion collectors in LA-ICP-MS (LA-MC-ICP-MS). The paper discusses the state of the art, the challenges and limits in isotope ratio measurements by LA-ICP-MS using different instrumentations at the trace and ultratrace level in different fields of application as in environmental and biological research, geochemistry and geochronology with respect to their precision and accuracy.

Lipid Correction for Carbon Stable Isotope Analysis of Deep-sea Fishes

EPA Science Inventory

Lipid extraction is used prior to stable isotope analysis of fish tissues to remove variability in the carbon stable isotope ratio (d13C) caused by varying lipid content among samples. Our objective was to evaluate an application of a mass balance correction for the effect of lip...

Trophic Interactions in Louisiana Salt Marshes: Combining Stomach Content, Stable Isotope, and Fatty Acid Approaches

NASA Astrophysics Data System (ADS)

Lopez-Duarte, P. C.; Able, K.; Fodrie, J.; McCann, M. J.; Melara, S.; Noji, C.; Olin, J.; Pincin, J.; Plank, K.; Polito, M. J.; Jensen, O.

2016-02-01

Multiple studies conducted over five years since the 2010 Macondo oil spill in the Gulf of Mexico indicate that oil impacts vary widely among taxonomic groups. For instance, fishes inhabiting the marsh surface show no clear differences in either community composition or population characteristics between oiled and unoiled sites, despite clear evidence of physiological impacts on individual fish. In contrast, marsh insects and spiders are sensitive to the effects of hydrocarbons. Both insects and spiders are components of the marsh food web and represent an important trophic link between marsh plants and higher trophic levels. Because differences in oil impacts throughout the marsh food web have the potential to significantly alter food webs and energy flow pathways and reduce food web resilience, our goal is to quantify differences in marsh food webs between oiled and unoiled sites to test the hypothesis that oiling has resulted in simpler and less resilient food webs. Diets and food web connections were quantified through a combination of stomach content, stable isotope, and fatty acid analysis. The combination of these three techniques provides a more robust approach to quantifying trophic relationships than any of these methods alone. Stomach content analysis provides a detailed snapshot of diets, while fatty acid and stable isotopes reflect diets averaged over weeks to months. Initial results focus on samples collected in May 2015 from a range of terrestrial and aquatic consumer species, including insects, mollusks, crustaceans, and piscivorous fishes.

Stable carbon and hydrogen isotope analysis of methyl tert-butyl ether and tert-amyl methyl ether by purge and trap-gas chromatography-isotope ratio mass spectrometry: method evaluation and application.

PubMed

Kujawinski, Dorothea M; Stephan, Manuel; Jochmann, Maik A; Krajenke, Karen; Haas, Joe; Schmidt, Torsten C

2010-01-01

In order to monitor the behaviour of contaminants in the aqueous environment effective enrichment techniques often have to be employed due to their low concentrations. In this work a robust and sensitive purge and trap-gas chromatography-isotope ratio mass spectrometry method for carbon and hydrogen isotope analysis of fuel oxygenates in water is presented. The method evaluation included the determination of method detection limits, accuracy and reproducibility of deltaD and delta(13)C values. Lowest concentrations at which reliable delta(13)C values could be determined were 5 microg L(-1) and 28 microg L(-1) for TAME and MTBE, respectively. Stable deltaD values for MTBE and TAME could be achieved for concentrations as low as 25 and 50 microg L(-1). Good long-term reproducibility of delta(13)C and deltaD values was obtained for all target compounds. But deltaD values varying more than 5 per thousand were observed using different thermal conversion tubes. Thus, a correction of deltaD values in the analysis of groundwater samples was necessary to guarantee comparability of the results. The applicability of this method was shown by the analysis of groundwater samples from a gasoline contaminated site. By two dimensional isotope analysis two locations within this site were identified at which anaerobic and aerobic degradation of methyl tert-butyl ether occurred.

Isotopic Discrimination of Perchlorate Sources in Ground Water

NASA Astrophysics Data System (ADS)

Bohlke, J.; Hatzinger, P. B.; Sturchio, N. C.; Gu, B.; Jackson, W. A.; Abbene, I. J.

2007-12-01

Perchlorate has been detected in ground water and drinking water in many areas of the U.S. during the past decade. Sources of potential perchlorate enrichment in ground water include releases from past military activities, fireworks manufacture and display, fertilizer applications, discarded road flares, and local atmospheric deposition. Here we present analyses of stable isotopes (δ37Cl, δ18O, and Δ17O) of dissolved perchlorate, along with other supporting environmental tracer data, from selected occurrences in ground water in the U.S. The isotope data indicate that both synthetic and natural perchlorate are present in ground water, and that multiple sources are present locally in some areas. The sampled ground waters generally were oxic and the perchlorate isotopes generally were not affected substantially by biodegradation. In some areas, natural perchlorate, with Δ17O = +7 to +10 ‰, can be attributed to agricultural applications of atmospherically derived natural nitrate fertilizer imported from South America (Atacama Desert, Chile). In at least one agricultural area in New York, concentrations of perchlorate increase with depth and ground-water age, possibly because of decreasing application rates of Atacama nitrate fertilizer and(or) decreasing perchlorate concentrations in the imported fertilizer products in recent years.

Natural isotope correction of MS/MS measurements for metabolomics and (13)C fluxomics.

PubMed

Niedenführ, Sebastian; ten Pierick, Angela; van Dam, Patricia T N; Suarez-Mendez, Camilo A; Nöh, Katharina; Wahl, S Aljoscha

2016-05-01

Fluxomics and metabolomics are crucial tools for metabolic engineering and biomedical analysis to determine the in vivo cellular state. Especially, the application of (13)C isotopes allows comprehensive insights into the functional operation of cellular metabolism. Compared to single MS, tandem mass spectrometry (MS/MS) provides more detailed and accurate measurements of the metabolite enrichment patterns (tandem mass isotopomers), increasing the accuracy of metabolite concentration measurements and metabolic flux estimation. MS-type data from isotope labeling experiments is biased by naturally occurring stable isotopes (C, H, N, O, etc.). In particular, GC-MS(/MS) requires derivatization for the usually non-volatile intracellular metabolites introducing additional natural isotopes leading to measurements that do not directly represent the carbon labeling distribution. To make full use of LC- and GC-MS/MS mass isotopomer measurements, the influence of natural isotopes has to be eliminated (corrected). Our correction approach is analyzed for the two most common applications; (13)C fluxomics and isotope dilution mass spectrometry (IDMS) based metabolomics. Natural isotopes can have an impact on the calculated flux distribution which strongly depends on the substrate labeling and the actual flux distribution. Second, we show that in IDMS based metabolomics natural isotopes lead to underestimated concentrations that can and should be corrected with a nonlinear calibration. Our simulations indicate that the correction for natural abundance in isotope based fluxomics and quantitative metabolomics is essential for correct data interpretation. © 2015 Wiley Periodicals, Inc.

Energy Transition Initiative: Island Energy Snapshot - San Andres and Providencia (Fact Sheet); NREL(National Renewable Energy Laboratory)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

This profile provides a snapshot of the energy landscape of the Archipelago of San Andres, Providencia, and Santa Catalina (unpopulated), also known as San Andres and Providencia, which is equidistant between Costa Rica and Jamaica and 775 kilometers northwest of Colombia. The archipelago is part of Colombia, though Nicaragua has also laid claim to it.

A snapshot of summer 2001 work zone activity : based on information reported on state road closure and construction websites

DOT National Transportation Integrated Search

2003-02-01

In a study sponsored by the Federal Highway Administration (FHWA), researchers conducted a survey of 789 work zones posted on 13 state road closure and construction websites during a two-week snapshot of the peak summer roadwork season in 2001. The g...

Isotopic Resonance Hypothesis: Experimental Verification by Escherichia coli Growth Measurements

NASA Astrophysics Data System (ADS)

Xie, Xueshu; Zubarev, Roman A.

2015-03-01

Isotopic composition of reactants affects the rates of chemical and biochemical reactions. As a rule, enrichment of heavy stable isotopes leads to progressively slower reactions. But the recent isotopic resonance hypothesis suggests that the dependence of the reaction rate upon the enrichment degree is not monotonous. Instead, at some ``resonance'' isotopic compositions, the kinetics increases, while at ``off-resonance'' compositions the same reactions progress slower. To test the predictions of this hypothesis for the elements C, H, N and O, we designed a precise (standard error +/-0.05%) experiment that measures the parameters of bacterial growth in minimal media with varying isotopic composition. A number of predicted resonance conditions were tested, with significant enhancements in kinetics discovered at these conditions. The combined statistics extremely strongly supports the validity of the isotopic resonance phenomenon (p << 10-15). This phenomenon has numerous implications for the origin of life studies and astrobiology, and possible applications in agriculture, biotechnology, medicine, chemistry and other areas.

Energy Transition Initiative: Island Energy Snapshot - Bonaire; U.S. Department of Energy (DOE), NREL (National Renewable Energy Laboratory)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2015-06-01

This profile provides a snapshot of the energy landscape of Bonaire, a special municipality of the Kingdom of the Netherlands located off the coast of Venezuela. Bonaire’s utility rates are approximately $0.35 per kilowatt-hour (kWh), above the Caribbean regional average of $0.33/kWh.

Energy Transition Initiative: Island Energy Snapshot - Curacao; U.S. Department of Energy (DOE), NREL (National Renewable Energy Laboratory)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2015-06-01

This profile provides a snapshot of the energy landscape of Curacao, an autonomous member of the Kingdom of the Netherlands located off the coast of Venezuela. Curacao’s utility rates are approximately $0.26 per kilowatt-hour (kWh), below the Caribbean regional average of $0.33/kWh.

Snapshot gradient-recalled echo-planar images of rat brains at long echo time at 9.4 T

PubMed Central

Lei, Hongxia; Mlynárik, Vladimir; Just, Nathalie; Gruetter, Rolf

2009-01-01

With improved B0 homogeneity along with satisfactory gradient performance at high magnetic fields, snapshot gradient-recalled echo-planar imaging (GRE-EPI) would perform at long echo times (TEs) on the order of T2*, which intrinsically allows obtaining strongly T2*-weighted images with embedded substantial anatomical details in ultrashort time. The aim of this study was to investigate the feasibility and quality of long TE snapshot GRE-EPI images of rat brain at 9.4 T. When compensating for B0 inhomogeneities, especially second-order shim terms, a 200×200 μm2 in-plane resolution image was reproducibly obtained at long TE (>25 ms). The resulting coronal images at 30 ms had diminished geometric distortions and, thus, embedded substantial anatomical details. Concurrently with the very consistent stability, such GRE-EPI images should permit to resolve functional data not only with high specificity but also with substantial anatomical details, therefore allowing coregistration of the acquired functional data on the same image data set. PMID:18486393

Quantitative Determination of Isotope Ratios from Experimental Isotopic Distributions

PubMed Central

Kaur, Parminder; O’Connor, Peter B.

2008-01-01

Isotope variability due to natural processes provides important information for studying a variety of complex natural phenomena from the origins of a particular sample to the traces of biochemical reaction mechanisms. These measurements require high-precision determination of isotope ratios of a particular element involved. Isotope Ratio Mass Spectrometers (IRMS) are widely employed tools for such a high-precision analysis, which have some limitations. This work aims at overcoming the limitations inherent to IRMS by estimating the elemental isotopic abundance from the experimental isotopic distribution. In particular, a computational method has been derived which allows the calculation of 13C/12C ratios from the whole isotopic distributions, given certain caveats, and these calculations are applied to several cases to demonstrate their utility. The limitations of the method in terms of the required number of ions and S/N ratio are discussed. For high-precision estimates of the isotope ratios, this method requires very precise measurement of the experimental isotopic distribution abundances, free from any artifacts introduced by noise, sample heterogeneity, or other experimental sources. PMID:17263354

Recent developments in application of stable isotope analysis on agro-product authenticity and traceability.

PubMed

Zhao, Yan; Zhang, Bin; Chen, Gang; Chen, Ailiang; Yang, Shuming; Ye, Zhihua

2014-02-15

With the globalisation of agro-product markets and convenient transportation of food across countries and continents, the potential for distribution of mis-labelled products increases accordingly, highlighting the need for measures to identify the origin of food. High quality food with identified geographic origin is a concern not only for consumers, but also for agriculture farmers, retailers and administrative authorities. Currently, stable isotope ratio analysis in combination with other chemical methods gradually becomes a promising approach for agro-product authenticity and traceability. In the last five years, a growing number of research papers have been published on tracing agro-products by stable isotope ratio analysis and techniques combining with other instruments. In these reports, the global variety of stable isotope compositions has been investigated, including light elements such as C, N, H, O and S, and heavy isotopes variation such as Sr and B. Several factors also have been considered, including the latitude, altitude, evaporation and climate conditions. In the present paper, an overview is provided on the authenticity and traceability of the agro-products from both animal and plant sources by stable isotope ratio analysis. Copyright © 2013 Elsevier Ltd. All rights reserved.

Following Carbon Isotopes from Methane to Molecules

NASA Astrophysics Data System (ADS)

Freeman, K. H.

2017-12-01

Continuous-flow methods introduced by Hayes (Matthews and Hayes, 1978; Freeman et al., 1990; Hayes et al., 1990) for compound-specific isotope analyses (CSIA) transformed how we study the origins and fates of organic compounds. This analytical revolution launched several decades of research in which researchers connect individual molecular structures to diverse environmental and climate processes affecting their isotopic profiles. Among the first applications, and one of the more dramatic isotopically, was tracing the flow of natural methane into cellular carbon and cellular biochemical constituents. Microbial oxidation of methane can be tracked by strongly 13C-depleted organic carbon in early Earth sedimentary environments, in marine and lake-derived biomarkers in oils, and in modern organisms and their environments. These signatures constrain microbial carbon cycling and inform our understanding of ocean redox. The measurement of molecular isotopes has jumped forward once again, and it is now possible to determine isotope abundances at specific positions within increasingly complex organic structures. In addition, recent analytical developments have lowered sample sensitivity limits of CSIA to picomole levels. These new tools have opened new ways to measure methane carbon in the natural environment and within biochemical pathways. This talk will highlight how molecular isotope methods enable us to follow the fate of methane carbon in complex environments and along diverse metabolic pathways, from trace fluids to specific carbon positions within microbial biomarkers.

Stable isotope deltas: Tiny, yet robust signatures in nature

USGS Publications Warehouse

Brand, Willi A.; Coplen, Tyler B.

2012-01-01

Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including 14C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. 13C, 2H, and 18O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as−25 per mil can be written as−25 mUr (or−2.5 cUr or−0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg ‘units’ are easily included (e.g. either+0.015 ‰ or+15 per meg

Stable isotopes in mid-ocean ridge hydrothermal systems: Interactions between fluids, minerals, and organisms

USGS Publications Warehouse

Shanks, Wayne C.; Böhlke, John Karl; Seal, Robert R.; Humphries, S.D.; Zierenberg, Robert A.; Mullineaux, Lauren S.; Thomson, Richard E.

1995-01-01

Studies of abundance variations of light stable isotopes in nature have had a tremendous impact on all aspects of geochemistry since the development, in 1947, of a gas source isotope ratio mass spectrometer capable of measuring small variations in stable isotope ratios (Nice, 1947]. Stable isotope geochemistry is now a mature field, as witnessed by the proliferation of commercially available mass spectrometers installed at virtually every major academic, government, and private-sector research geochemistry laboratory. A recent search of a literature database revealed over 3,000 articles that utilized stable isotope geochemistry over the last 20 years. Nonetheless, many exciting new technical developments are leading to exciting new discoveries and applications. In particular, micro-analytical techniques involving new generations of laser- and ion-microprobes are revolutionizing the types of analyses that can be done on spot sizes as small as a few tens of micrometers [Shanks and Criss, 1989]. New generations of conventional gas source and thermal ionization mass spectrometers, with high levels of automation and increased sensitivity and precision, are allowing analyses of large numbers of samples, like those needed for stable isotope stratigraphy in marine sediments, and are enabling the development and application of new isotopic systems.

Stable isotopes in mid-ocean ridge hydrothermal systems: Interactions between fluids, minerals, and organisms

NASA Astrophysics Data System (ADS)

Shanks, W. C., III; Böhlke, J. K.; Seal, R. R., II

Studies of abundance variations of light stable isotopes in nature have had a tremendous impact on all aspects of geochemistry since the development, in 1947, of a gas source isotope ratio mass spectrometer capable of measuring small variations in stable isotope ratios [Nier, 1947] Stable isotope geochemistry is now a mature field, as witnessed by the proliferation of commercially available mass spectrometers installed at virtually every major academic, government, and private-sector research geochemistry laboratory. A recent search of a literature database revealed over 3,000 articles that utilized stable isotope geochemistry over the last 20 years. Nonetheless, many exciting new technical developments are leading to exciting new discoveries and applications. In particular, micro analytical techniques involving new generations of laser- and ion-microprobes are revolutionizing the types of analyses that can be done on spot sizes as small as a few tens of micrometers [Shanks and Criss, 1989]. New generations of conventional gas source and thermal ionization mass spectrometers, with high levels of automation and increased sensitivity and precision, are allowing analyses of large numbers of samples, like those needed for stable isotope stratigraphy in marine sediments, and are enabling the development and application of new isotopic systems.

Preservation of carbonate clumped isotopes in sedimentary paleoclimate archives

NASA Astrophysics Data System (ADS)

Henkes, G. A.; Passey, B. H.; Grossman, E. L.; Shenton, B.; Perez-Huerta, A.

2014-12-01

Carbonate clumped isotope thermometry is increasingly used to reconstruct paleotemperatures of ancient terrestrial environments. One promising application is elucidating paleoelevation from carbonate archives such as paleosols, lacustrine marls, and fossil freshwater shells. Unlike conventional stable isotope approaches (e.g., mineral δ18O or δD), clumped isotope thermometry is independent of the isotopic composition of the precipitating waters and can therefore be used to reconstruct elevation by both the temperature-altitude relationship and the rainfall δ18O-altitude relationship. However, interpretation of clumped isotope data is not without its own complications. Like conventional stable isotopes, clumped isotope paleotemperatures can be effectively reset to warmer values by dissolution/reprecipitation-type diagenesis during sedimentary burial. It is also known that carbonate clumped isotope bonds (i.e., 13C-18O) are susceptible to 'reordering' in the solid mineral lattice at warmer burial temperatures, with laboratory studies of natural carbonates indicating activation of this phenomenon at temperatures as low as 100 °C over geologic timescales. A challenge in applying carbonate clumped isotope thermometry to natural samples is now evaluating terrestrial archives with respect to both types of alteration: 'open-system' alteration and 'closed-system' bond reordering. In this talk we will review our experimental efforts to constrain the kinetics of clumped isotope reordering, with relevance to low-temperature carbonates like fossil shells and early diagenetic minerals, and present new laboratory data that further inform our theoretical framework for the mechanism(s) of 13C-18O bond reordering. Together with traditional analytical and petrographic screening for recrystallization, empirical and laboratory studies of carbonate clumped isotope reordering represent the next steps in evaluating isotopic records of paleoclimate, paleobiology, and paleoelevation

Quantification of spatial and seasonal variations in the proportional contribution of nitrate sources using a multi-isotope approach and Bayesian isotope mixing model.

PubMed

Meghdadi, Aminreza; Javar, Narmin

2018-04-01

Spatial and seasonal variations in nitrate contamination are a globally concern. While numerous studies have used δ 15 N-NO 3 and δ 18 O-NO 3 to elucidate the dominant sources of nitrate in groundwater, this approach has significant limitations due to the overlap of nitrate isotopic ranges and the occurrence of nitrate isotopic fractionation. This study quantitatively assessed the spatial and seasonal variations in the proportional contributions of nitrate sources from different land uses in the Tarom watershed in North-West Iran. To achieve this aim, orthogonal projection of the hydrochemical and isotopic dataset of the principal component analysis (PCA) as well as correlation coefficient matrix (Corr-PCA) were evaluated to reduce the dimensionality of the inter-correlated dataset. Next, a nitrate isotopic biplot accompanied with a Bayesian isotope mixing model (SIAR) were applied to specify the spatial and seasonal trends in the proportional contribution of three dominant sources of nitrate (fertilizers, animal manure and residential waste) in the watershed. Finally, in order to provide a sensitive framework for nitrate source appointment and overcome the associated limitations of dual nitrate isotope application, the integration of boron isotope (δ 11 B) and strontium isotopic ratio ( 87 Sr/ 86 Sr) was introduced. The results revealed that the mean contribution of residential sewage increased (17%-27.5%), while the mean contribution of fertilizers decreased (28.3%-19%), from late spring to early autumn. Also, fertilizer was the highest contributor (42.1% ± 3.2) during late spring, especially in regions with more than 75% agricultural land. Meanwhile, the mean contribution of sewage was highest in early autumn (32.1% ± 2.8) in the areas with more than 20% residential land. These results were confirmed by coupled application of δ 11 B and 87 Sr/ 86 Sr. This study provides a useful insight for environmental managers to verify groundwater pollution

Visual navigation in desert ants Cataglyphis fortis: are snapshots coupled to a celestial system of reference?

PubMed

Akesson, Susanne; Wehner, Rüdiger

2002-07-01

Central-place foraging insects such as desert ants of the genus Cataglyphis use both path integration and landmarks to navigate during foraging excursions. The use of landmark information and a celestial system of reference for nest location was investigated by training desert ants returning from an artificial feeder to find the nest at one of four alternative positions located asymmetrically inside a four-cylinder landmark array. The cylindrical landmarks were all of the same size and arranged in a square, with the nest located in the southeast corner. When released from the compass direction experienced during training (southeast), the ants searched most intensely at the fictive nest position. When instead released from any of the three alternative directions of approach (southwest, northwest or northeast), the same individuals instead searched at two of the four alternative positions by initiating their search at the position closest to the direction of approach when entering the landmark square and then returning to the position at which snapshot, current landmark image and celestial reference information were in register. The results show that, in the ants' visual snapshot memory, a memorized landmark scene can temporarily be decoupled from a memorized celestial system of reference.

A Gemini snapshot survey for double degenerates

NASA Astrophysics Data System (ADS)

Kilic, Mukremin; Brown, Warren R.; Gianninas, A.; Curd, Brandon; Bell, Keaton J.; Allende Prieto, Carlos

2017-11-01

We present the results from a Gemini snapshot radial-velocity survey of 44 low-mass white-dwarf candidates selected from the Sloan Digital Sky Survey (SDSS) spectroscopy. To find sub-hour orbital period binary systems, our time-series spectroscopy had cadences of 2-8 min over a period of 20-30 min. Through follow-up observations at Gemini and the MMT, we identify four double-degenerate binary systems with periods ranging from 53 min to 7 h. The shortest period system, SDSS J123549.88+154319.3, was recently identified as a sub-hour period detached binary by Breedt and collaborators. Here, we refine the orbital and physical parameters of this system. High-speed and time-domain survey photometry observations do not reveal eclipses or other photometric effects in any of our targets. We compare the period distribution of these four systems with the orbital period distribution of known double white dwarfs; the median period decreases from 0.64 to 0.24 d for M = 0.3-0.5 M⊙ to M < 0.3 M⊙ white dwarfs. However, we do not find a statistically significant correlation between the orbital period and white-dwarf mass.

The Snapshot A Star SurveY (SASSY)

NASA Astrophysics Data System (ADS)

Garani, Jasmine I.; Nielsen, Eric; Marchis, Franck; Liu, Michael C.; Macintosh, Bruce; Rajan, Abhijith; De Rosa, Robert J.; Jinfei Wang, Jason; Esposito, Thomas M.; Best, William M. J.; Bowler, Brendan; Dupuy, Trent; Ruffio, Jean-Baptiste

2018-01-01

The Snapshot A Star Survey (SASSY) is an adaptive optics survey conducted using NIRC2 on the Keck II telescope to search for young, self-luminous planets and brown dwarfs (M > 5MJup) around high mass stars (M > 1.5 M⊙). We present the results of a custom data reduction pipeline developed for the coronagraphic observations of our 200 target stars. Our data analysis method includes basic near infrared data processing (flat-field correction, bad pixel removal, distortion correction) as well as performing PSF subtraction through a Reference Differential Imaging algorithm based on a library of PSFs derived from the observations using the pyKLIP routine. We present the results from the pipeline of a few stars from the survey with analysis of candidate companions. SASSY is sensitive to companions 600,000 times fainter than the host star withint the inner few arcseconds, allowing us to detect companions with masses ~8MJup at age 110 Myr. This work was supported by the Leadership Alliance's Summer Research Early Identification Program at Stanford University, the NSF REU program at the SETI Institute and NASA grant NNX14AJ80G.

The Snapshot A-Star SurveY (SASSY)

NASA Astrophysics Data System (ADS)

Garani, Jasmine; Nielsen, Eric L.; Marchis, Franck; Liu, Michael C.; Macintosh, Bruce; Rajan, Abhijith; De Rosa, Robert J.; Wang, Jason; Esposito, Thomas; Best, William M. J.; Bowler, Brendan P.; Dupuy, Trent J.; Ruffio, Jean-Baptise

2017-01-01

We present the Snapshot A-Star SurveY (SASSY), an adaptive optics survey conducted using NIRC2 on the Keck II telescope to search for young, self-luminious planets and brown dwarfs (M > 5MJup) around high mass stars (M > 1.5 M⊙). We describe a custom data-reduction pipeline developed for the coronagraphic observations of our 200 target stars. Our data analysis method includes basic near infrared data processing (flat-field correction, bad pixel removal, distortion correction) as well as performing PSF subtraction through a Reference Differential Imaging algorithm based on a library of PSFs derived from the observations using the pyKLIP routine. We present early results from the survey including planet and brown dwarf candidates and the status of ongoing follow-up observations. Utilizing the high contrast of Keck NIRC2 coronagraphic observations, SASSY reaches sensitivity to brown dwarfs and planetary mass companions at separations between 0.6'' and 4''. With over 200 stars observed we are tripling the number of high-mass stars imaged at these contrasts and sensitivities compared to previous surveys. This work was supported by the NSF REU program at the SETI Institute and NASA grant NNX14AJ80G.

Static, Mixed-Array Total Evaporation for Improved Quantitation of Plutonium Minor Isotopes in Small Samples

NASA Astrophysics Data System (ADS)

Stanley, F. E.; Byerly, Benjamin L.; Thomas, Mariam R.; Spencer, Khalil J.

2016-06-01

Actinide isotope measurements are a critical signature capability in the modern nuclear forensics "toolbox", especially when interrogating anthropogenic constituents in real-world scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (<10-6) within already limited quantities of sample. Herein, we investigate the application of static, mixed array total evaporation techniques as a straightforward means of improving plutonium minor isotope measurements, which have been resistant to enhancement in recent years because of elevated radiologic concerns. Results are presented for small sample (~20 ng) applications involving a well-known plutonium isotope reference material, CRM-126a, and compared with traditional total evaporation methods.

Static, Mixed-Array Total Evaporation for Improved Quantitation of Plutonium Minor Isotopes in Small Samples.

PubMed

Stanley, F E; Byerly, Benjamin L; Thomas, Mariam R; Spencer, Khalil J

2016-06-01

Actinide isotope measurements are a critical signature capability in the modern nuclear forensics "toolbox", especially when interrogating anthropogenic constituents in real-world scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (<10(-6)) within already limited quantities of sample. Herein, we investigate the application of static, mixed array total evaporation techniques as a straightforward means of improving plutonium minor isotope measurements, which have been resistant to enhancement in recent years because of elevated radiologic concerns. Results are presented for small sample (~20 ng) applications involving a well-known plutonium isotope reference material, CRM-126a, and compared with traditional total evaporation methods. Graphical Abstract ᅟ.

A critical examination of the possible application of zinc stable isotope ratios in bivalve mollusks and suspended particulate matter to trace zinc pollution in a tropical estuary.

PubMed

Araújo, Daniel; Machado, Wilson; Weiss, Dominik; Mulholland, Daniel S; Boaventura, Geraldo R; Viers, Jerome; Garnier, Jeremie; Dantas, Elton L; Babinski, Marly

2017-07-01

The application of zinc (Zn) isotopes in bivalve tissues to identify zinc sources in estuaries was critically assessed. We determined the zinc isotope composition of mollusks (Crassostrea brasiliana and Perna perna) and suspended particulate matter (SPM) in a tropical estuary (Sepetiba Bay, Brazil) historically impacted by metallurgical activities. The zinc isotope systematics of the SPM was in line with mixing of zinc derived from fluvial material and from metallurgical activities. In contrast, source mixing alone cannot account for the isotope ratios observed in the bivalves, which are significantly lighter in the contaminated metallurgical zone (δ 66 Zn JMC  = +0.49 ± 0.06‰, 2σ, n = 3) compared to sampling locations outside (δ 66 Zn JMC  = +0.83 ± 0.10‰, 2σ, n = 22). This observation suggests that additional factors such as speciation, bioavailability and bioaccumulation pathways (via solution or particulate matter) influence the zinc isotope composition of bivalves. Copyright © 2017 Elsevier Ltd. All rights reserved.

A novel snapshot polarimetric imager

NASA Astrophysics Data System (ADS)

Wong, Gerald; McMaster, Ciaran; Struthers, Robert; Gorman, Alistair; Sinclair, Peter; Lamb, Robert; Harvey, Andrew R.

2012-10-01

Polarimetric imaging (PI) is of increasing importance in determining additional scene information beyond that of conventional images. For very long-range surveillance, image quality is degraded due to turbulence. Furthermore, the high magnification required to create images with sufficient spatial resolution suitable for object recognition and identification require long focal length optical systems. These are incompatible with the size and weight restrictions for aircraft. Techniques which allow detection and recognition of an object at the single pixel level are therefore likely to provide advance warning of approaching threats or long-range object cueing. PI is a technique that has the potential to detect object signatures at the pixel level. Early attempts to develop PI used rotating polarisers (and spectral filters) which recorded sequential polarized images from which the complete Stokes matrix could be derived. This approach has built-in latency between frames and requires accurate registration of consecutive frames to analyze real-time video of moving objects. Alternatively, multiple optical systems and cameras have been demonstrated to remove latency, but this approach increases cost and bulk of the imaging system. In our investigation we present a simplified imaging system that divides an image into two orthogonal polarimetric components which are then simultaneously projected onto a single detector array. Thus polarimetric data is recorded without latency on a single snapshot. We further show that, for pixel-level objects, the data derived from only two orthogonal states (H and V) is sufficient to increase the probability of detection whilst reducing false alarms compared to conventional unpolarised imaging.

Applications of DNA-Stable Isotope Probing in Bioremediation Studies

NASA Astrophysics Data System (ADS)

Chen, Yin; Vohra, Jyotsna; Murrell, J. Colin

DNA-stable isotope probing, a method to identify active microorganisms without the prerequisite of cultivation, has been widely applied in the study of microorganisms involved in the degradation of environmental pollutants. Recent advances and technique considerations in applying DNA-SIP in bioremediation are highlighted. A detailed protocol of a DNA-SIP experiment is provided.

Applications of DNA-stable isotope probing in bioremediation studies.

PubMed

Chen, Yin; Vohra, Jyotsna; Murrell, J Colin

2010-01-01

DNA-stable isotope probing, a method to identify active microorganisms without the prerequisite of cultivation, has been widely applied in the study of microorganisms involved in the degradation of environmental pollutants. Recent advances and technique considerations in applying DNA-SIP in bioremediation are highlighted. A detailed protocol of a DNA-SIP experiment is provided.

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

NASA Astrophysics Data System (ADS)

Harilal, S. S.; Brumfield, B. E.; LaHaye, N. L.; Hartig, K. C.; Phillips, M. C.

2018-06-01

Rapid, in-field, and non-contact isotopic analysis of solid materials is extremely important to a large number of applications, such as nuclear nonproliferation monitoring and forensics, geochemistry, archaeology, and biochemistry. Presently, isotopic measurements for these and many other fields are performed in laboratory settings. Rapid, in-field, and non-contact isotopic analysis of solid material is possible with optical spectroscopy tools when combined with laser ablation. Laser ablation generates a transient vapor of any solid material when a powerful laser interacts with a sample of interest. Analysis of atoms, ions, and molecules in a laser-produced plasma using optical spectroscopy tools can provide isotopic information with the advantages of real-time analysis, standoff capability, and no sample preparation requirement. Both emission and absorption spectroscopy methods can be used for isotopic analysis of solid materials. However, applying optical spectroscopy to the measurement of isotope ratios from solid materials presents numerous challenges. Isotope shifts arise primarily due to variation in nuclear charge distribution caused by different numbers of neutrons, but the small proportional nuclear mass differences between nuclei of various isotopes lead to correspondingly small differences in optical transition wavelengths. Along with this, various line broadening mechanisms in laser-produced plasmas and instrumental broadening generated by the detection system are technical challenges frequently encountered with emission-based optical diagnostics. These challenges can be overcome by measuring the isotope shifts associated with the vibronic emission bands from molecules or by using the techniques of laser-based absorption/fluorescence spectroscopy to marginalize the effect of instrumental broadening. Absorption and fluorescence spectroscopy probe the ground state atoms existing in the plasma when it is cooler, which inherently provides narrower

A new method and application for determining the nitrogen isotopic composition of NOx

NASA Astrophysics Data System (ADS)

Hastings, M. G.; Miller, D. J.; Wojtal, P.; O'Connor, M.

2015-12-01

Atmospheric nitrogen oxides (NOx = NO + NO2) play key roles in atmospheric chemistry, air quality, and radiative forcing, and contribute to nitric acid deposition. Sources of NOx include both natural and anthropogenic emissions, which vary significantly in space and time. NOx isotopic signatures offer a potentially valuable tool to trace source impacts on atmospheric chemistry and regional acid deposition. Previous work on NOx isotopic signatures suggests large ranges in values, even from the same emission source, as well as overlapping ranges amongst different sources, making it difficult to use the isotopic composition as a quantitative tracer of source influences. These prior measurements have utilized a variety of methods for collecting the NOx as nitrate or nitrite for isotopic analysis, and testing of some of these methods (including active and passive collections) reveal inconsistencies in efficiency of collection, as well as issues related to changes in conditions such as humidity, temperature, and NOx fluxes. A recently developed method allows for accurately measuring the nitrogen isotopic composition of NOx (NOx = NO + NO2) after capturing the NOx in a potassium permanganate/sodium hydroxide solution as nitrate (Fibiger et al., Anal. Chem., 2014). The method has been thoroughly tested in the laboratory and field, and efficiently collects NO and NO2 under a variety of conditions. There are several advantages to collecting NOx actively, including the ability to collect over minutes to hourly time scales, and the ability to collect in environments with highly variable NOx sources and concentrations. Challenges include a nitrate background present in potassium permanganate (solid and liquid forms), accurately deriving ambient NOx concentrations based upon flow rate and solution concentrations above this variable background, and potential interferences from other nitrogen species. This method was designed to collect NOx in environments with very different

Non-traditional isotopes in analytical ecogeochemistry assessed by MC-ICP-MS

NASA Astrophysics Data System (ADS)

Prohaska, Thomas; Irrgeher, Johanna; Horsky, Monika; Hanousek, Ondřej; Zitek, Andreas

2014-05-01

Analytical ecogeochemistry deals with the development and application of tools of analytical chemistry to study dynamic biological and ecological processes within ecosystems and across ecosystem boundaries in time. It can be best described as a linkage between modern analytical chemistry and a holistic understanding of ecosystems ('The total human ecosystem') within the frame of transdisciplinary research. One focus of analytical ecogeochemistry is the advanced analysis of elements and isotopes in abiotic and biotic matrices and the application of the results to basic questions in different research fields like ecology, environmental science, climatology, anthropology, forensics, archaeometry and provenancing. With continuous instrumental developments, new isotopic systems have been recognized for their potential to study natural processes and well established systems could be analyzed with improved techniques, especially using multi collector inductively coupled plasma mass spectrometry (MC-ICP-MS). For example, in case of S, isotope ratio measurements at high mass resolution could be achieved at much lower S concentrations with ICP-MS as compared to IRMS, still keeping suitable uncertainty. Almost 50 different isotope systems have been investigated by ICP-MS, so far, with - besides Sr, Pb and U - Ca, Mg, Cd, Li, Hg, Si, Ge and B being the most prominent and considerably pushing the limits of plasma based mass spectrometry also by applying high mass resolution. The use of laser ablation in combination with MC-ICP-MS offers the possibility to achieve isotopic information on high spatial (µm-range) and temporal scale (in case of incrementally growing structures). The information gained with these analytical techniques can be linked between different hierarchical scales in ecosystems, offering means to better understand ecosystem processes. The presentation will highlight the use of different isotopic systems in ecosystem studies accomplished by ICP-MS. Selected

Capturing snapshots of APE1 processing DNA damage

DOE PAGES

Freudenthal, Bret D.; Beard, William A.; Cuneo, Matthew J.; ...

2015-10-12

DNA apurinic-apyrimidinic (AP) sites are prevalent noncoding threats to genomic stability and are processed by AP endonuclease 1 (APE1). APE1 incises the AP-site phosphodiester backbone, generating a DNA-repair intermediate that is potentially cytotoxic. The molecular events of the incision reaction remain elusive, owing in part to limited structural information. Here we report multiple high-resolution human APE1-DNA structures that divulge new features of the APE1 reaction, including the metal-binding site, the nucleophile and the arginine clamps that mediate product release. We also report APE1-DNA structures with a T-G mismatch 5' to the AP site, representing a clustered lesion occurring in methylatedmore » CpG dinucleotides. Moreover, these structures reveal that APE1 molds the T-G mismatch into a unique Watson-Crick-like geometry that distorts the active site, thus reducing incision. Finally, these snapshots provide mechanistic clarity for APE1 while affording a rational framework to manipulate biological responses to DNA damage.« less

Single-snapshot DOA estimation by using Compressed Sensing

NASA Astrophysics Data System (ADS)

Fortunati, Stefano; Grasso, Raffaele; Gini, Fulvio; Greco, Maria S.; LePage, Kevin

2014-12-01

This paper deals with the problem of estimating the directions of arrival (DOA) of multiple source signals from a single observation vector of an array data. In particular, four estimation algorithms based on the theory of compressed sensing (CS), i.e., the classical ℓ 1 minimization (or Least Absolute Shrinkage and Selection Operator, LASSO), the fast smooth ℓ 0 minimization, and the Sparse Iterative Covariance-Based Estimator, SPICE and the Iterative Adaptive Approach for Amplitude and Phase Estimation, IAA-APES algorithms, are analyzed, and their statistical properties are investigated and compared with the classical Fourier beamformer (FB) in different simulated scenarios. We show that unlike the classical FB, a CS-based beamformer (CSB) has some desirable properties typical of the adaptive algorithms (e.g., Capon and MUSIC) even in the single snapshot case. Particular attention is devoted to the super-resolution property. Theoretical arguments and simulation analysis provide evidence that a CS-based beamformer can achieve resolution beyond the classical Rayleigh limit. Finally, the theoretical findings are validated by processing a real sonar dataset.

Investigation of the Photochemical Method for Uranium Isotope Separation

DOE R&D Accomplishments Database

Urey, H. C.

1943-07-10

To find a process for successful photochemical separation of isotopes several conditions have to be fulfilled. First, the different isotopes have to show some differences in the spectrum. Secondly, and equally important, this difference must be capable of being exploited in a photochemical process. Parts A and B outline the physical and chemical conditions, and the extent to which one might expect to find them fulfilled. Part C deals with the applicability of the process.

Methane clumped isotopes: Progress and potential for a new isotopic tracer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Douglas, Peter M. J.; Stolper, Daniel A.; Eiler, John M.

The isotopic composition of methane is of longstanding geochemical interest, with important implications for understanding hydrocarbon systems, atmospheric greenhouse gas concentrations, the global carbon cycle, and life in extreme environments. Recent analytical developments focusing on multiply substituted isotopologues (‘clumped isotopes’) are opening a potentially valuable new window into methane geochemistry. When methane forms in internal isotopic equilibrium, clumped isotopes can provide a direct record of formation temperature, making this property particularly valuable for identifying different methane origins. However, it has also become clear that in certain settings methane clumped isotope measurements record kinetic rather than equilibrium isotope effects. Here wemore » present a substantially expanded dataset of methane clumped isotope analyses, and provide a synthesis of the current interpretive framework for this parameter. We review different processes affecting methane clumped isotope compositions, describe the relationships between conventional isotope and clumped isotope data, and summarize the types of information that this measurement can provide in different Earth and planetary environments.« less

Static, mixed-array total evaporation for improved quantitation of plutonium minor isotopes in small samples

DOE PAGES

Stanley, F. E.; Byerly, Benjamin L.; Thomas, Mariam R.; ...

2016-03-31

Actinide isotope measurements are a critical signature capability in the modern nuclear forensics “toolbox”, especially when interrogating anthropogenic constituents in real-world scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (<10 -6) within already limited quantities of sample. Herein, we investigate the application of static, mixed array total evaporation techniques as a straightforward means of improving plutonium minor isotope measurements, which have been resistant to enhancement in recent years because of elevated radiologic concerns. Furthermore, results are presented for small sample (~20 ng) applications involving a well-knownmore » plutonium isotope reference material, CRM-126a, and compared with traditional total evaporation methods.« less

Application and validation of isotope dilution method (IDM) for predicting bioavailability of hydrophobic organic contaminants in soil.

PubMed

Wang, Jie; Taylor, Allison; Schlenk, Daniel; Gan, Jay

2018-05-01

Risk assessment of hydrophobic organic contaminants (HOCs) using the total chemical concentration following exhaustive extraction may overestimate the actual availability of HOCs to non-target organisms. Existing methods for estimating HOC bioavailability in soil have various operational limitations. In this study, we explored the application of isotope dilution method (IDM) to quantify the accessible fraction (E) of DDTs and PCBs in both historically-contaminated and freshly-spiked soils. After addition of 13 C or deuterated analogues to a soil sample, the phase distribution of isotope-labeled and native chemicals reached an apparent equilibrium within 48 h of mixing. The derived E values in the three soils ranged from 0.19 to 0.82, depending on the soil properties and also the contact time of HOCs (i.e., aging). The isotope dilution method consistently predicted greater accumulation into earthworm (Eisenia fetida) than that by polyethylene (PE) or solid phase microextraction (SPME) sampler, likely because desorption in the gut enhanced bioavailability of soil-borne HOCs. A highly significant linear regression (R 2  = 0.91) was found between IDM and 24-h Tenax desorption, with a slope statistically identical to 1. The IDM-derived accessible concentration (C e ) was further shown to accurately predict tissue residues in earthworm exposed in the same soils. Given the relatively short duration and simple steps, IDM has the potential to be readily adopted for measuring HOC bioaccessibility in soil and for improving risk assessment and evaluation of remediation efficiency. Copyright © 2018 Elsevier Ltd. All rights reserved.

Isotopic Analysis of Fingernails as a USGS Open House Demonstration of the Use of Stable Isotopes in Foodweb Studies

NASA Astrophysics Data System (ADS)

Silva, S. R.; Kendall, C.; Young, M. B.; Choy, D.

2011-12-01

The USGS Isotope Tracers Project uses stable isotopes and tritium to add a unique dimension of chemical information to a wide range of environmental investigations. The use and application of isotopes is usually an unfamiliar and even esoteric topic to the general public. Therefore during three USGS open house events, as a public outreach effort, we demonstrated the use of stable isotopes by analyzing nitrogen and carbon isotopes from very small fragments of fingernail from willing participants. We titled the exhibit "You Are What You Eat". The results from all participants were plotted on a graph indicating the general influence of different food groups on the composition of body tissues as represented by fingernails. All participants were assigned a number and no personal-identification information was collected. A subset of participants provided us with an estimate of the number of days a week various foods were eaten and if they were vegetarians, vegans or non-vegetarians. Volunteers from our research group were on hand to explain and discuss fundamental concepts such as how foods attain their isotopic composition, the difference between C3 and C4 plants, the effects of assimilation, trophic enrichment, and the various uses of stable isotopes in environmental studies. The results of the fingernail analyses showed the variation of the range of isotopic compositions among about 400 people at each event, the distinct influence of C4 plants (mainly corn and cane sugar) on our carbon isotopic composition, and the isotopic differences between vegetarians and non vegetarians among other details (http://wwwrcamnl.wr.usgs.gov/isoig/projects/fingernails/). A poll of visitors attending the open house event in 2006 indicated that "You Are What You Eat" was among the most popular exhibits. Following the first two open house events we were contacted by a group of researchers from Brazil who had completed a very similar study. Our collaboration resulted in a publication in

Forensic analysis of explosives using isotope ratio mass spectrometry (IRMS)--preliminary study on TATP and PETN.

PubMed

Benson, Sarah J; Lennard, Christopher J; Maynard, Philip; Hill, David M; Andrew, Anita S; Roux, Claude

2009-06-01

The application of isotopic techniques to investigations requiring the provision of evidence to a Court is limited. The objective of this research was to investigate the application of light stable isotopes and isotope ratio mass spectrometry (IRMS) to solve complex forensic cases by providing a level of discrimination not achievable utilising traditional forensic techniques. Due to the current threat of organic peroxide explosives, such as triacetone triperoxide (TATP), research was undertaken to determine the potential of IRMS to differentiate samples of TATP that had been manufactured utilising different starting materials and/or manufacturing processes. In addition, due to the prevalence of pentaerythritoltetranitrate (PETN) in detonators, detonating cord, and boosters, the potential of the IRMS technique to differentiate PETN samples from different sources was also investigated. Carbon isotope values were measured in fourteen TATP samples, with three definite groups appearing in the initial sample set based on the carbon data alone. Four additional TATP samples (in a second set of samples) were distinguishable utilising the carbon and hydrogen isotopic compositions individually, and also in combination with the oxygen isotope values. The 3D plot of the carbon, oxygen and hydrogen data demonstrated the clear discrimination of the four samples of TATP. The carbon and nitrogen isotope values measured from fifteen PETN samples, allowed samples from different sources to be readily discriminated. This paper demonstrates the successful application of IRMS to the analysis of explosives of forensic interest to assist in discriminating samples from different sources. This research represents a preliminary evaluation of the IRMS technique for the measurement of stable isotope values in TATP and PETN samples, and supports the dedication of resources for a full evaluation of this application in order to achieve Court reportable IRMS results.

Development of procedure for measurement of Pb isotope ratios in seawater by application of seaFAST sample pre-treatment system and Sector Field Inductively Coupled Plasma Mass Spectrometry

NASA Astrophysics Data System (ADS)

Vassileva, Emilia; Wysocka, Irena

2016-12-01

Anthropogenic Pb in the oceans, derived from high-temperature industrial processes, fuel combustion and incineration can have an isotopic signature distinct from naturally occurring Pb, supplied by rock weathering. To identify the different pollution sources accurately and to quantify their relative contributions, Pb isotope ratios are widely used. Due to the high salt content (approximately 3.5% of total dissolved solids) and very low levels of Pb (typically from 1 to 100 ng L- 1) in seawater the determination of Pb isotope ratios requires preliminary matrix separation and analyte preconcentration. An analytical protocol for the measurements of Pb isotope ratios in seawater combining seaFAST sample pre-treatment system and Sector Field Inductively Coupled Plasma Mass Spectrometry (SF ICP-MS) was developed. The application of seaFAST system was advantageous, because of its completely closed working cycle and small volumes of chemicals introduced in pre-treatment step, resulting in very low detection limits and procedural blanks. The preconcentration/matrix separation step was also of crucial importance for minimizing the isobaric and matrix interferences, coming from the seawater. In order to differentiate between anthropogenic and natural Pb sources, particular attention was paid to the determination of 204Pb isotope because of its implication in some geological interpretations. The validation of the analytical procedure was effectuated according to the recommendations of the ISO/IEC 17025 standard. The method was validated by processing the common Pb isotope reference material NIST SRM 981. All major sources of uncertainty were identified and propagated together following the ISO/GUM guidelines. The estimation of the total uncertainty associated to each measurement result was fundamental tool for sorting the main sources of possible biases. The developed analytical procedure was applied to the coastal and open seawater samples, collected in different regions of

Investigating isotopic signatures of atmospheric nitrous acid (HONO)

NASA Astrophysics Data System (ADS)

Chai, J.; Miller, D. J.; Hastings, M. G.

2016-12-01

Nitrous acid (HONO) is an important reactive nitrogen species that can be easily photolyzed to nitrogen oxide and hydroxyl radical in the troposphere. HONO greatly influences atmospheric oxidation capacity, affecting the formation of tropospheric ozone (O3) and secondary aerosol. Recent studies have indicated that in addition to heterogeneous NOx reactions, biomass burning, soil emission and photolysis of nitric acid (HNO3) on surfaces (e.g. aerosol particles and soot) are also important sources of HONO. However, these sources have not yet been well constrained. The stable isotope ratios in nitrate have been successfully used to trace NOx sources and oxidation chemistry in the atmosphere. Can the isotopic signatures of HONO be used to trace NOx oxidation and renoxification pathways? For this purpose, we have built an annular denuder HONO collection system for the stable isotope study of HONO. Preliminary tests show successful collection and recovery of HONO synthesized in our lab. Nitrogen and oxygen isotopic analysis of the recovered HONO also shows consistent isotopic signatures. Results from field applications of this method in near road and on road environments, agricultural settings, and laboratory based biomass burns will be presented.

Oxygen isotope study of the Long Valley magma system, California: isotope thermometry and convection in large silicic magma bodies

NASA Astrophysics Data System (ADS)

Bindeman, Ilya; Valley, John

2002-07-01

Products of voluminous pyroclastic eruptions with eruptive draw-down of several kilometers provide a snap-shot view of batholith-scale magma chambers, and quench pre-eruptive isotopic fractionations (i.e., temperatures) between minerals. We report analyses of oxygen isotope ratio in individual quartz phenocrysts and concentrates of magnetite, pyroxene, and zircon from individual pumice clasts of ignimbrite and fall units of caldera-forming 0.76 Ma Bishop Tuff (BT), pre-caldera Glass Mountain (2.1-0.78 Ma), and post-caldera rhyolites (0.65-0.04 Ma) to characterize the long-lived, batholith-scale magma chamber beneath Long Valley Caldera in California. Values of δ18O show a subtle 1‰ decrease from the oldest Glass Mountain lavas to the youngest post-caldera rhyolites. Older Glass Mountain lavas exhibit larger ( 1‰) variability of δ18O(quartz). The youngest domes of Glass Mountain are similar to BT in δ18O(quartz) values and reflect convective homogenization during formation of BT magma chamber surrounded by extremely heterogeneous country rocks (ranging from 2 to +29‰). Oxygen isotope thermometry of BT confirms a temperature gradient between "Late" (815 °C) and "Early" (715 °C) BT. The δ18O(quartz) values of "Early" and "Late" BT are +8.33 and 8.21‰, consistent with a constant δ18O(melt)=7.8+/-0.1‰ and 100 °C temperature difference. Zircon-melt saturation equilibria gives a similar temperature range. Values of δ18O(quartz) for different stratigraphic units of BT, and in pumice clasts ranging in pre-eruptive depths from 6 to 11 km (based on melt inclusions), and document vertical and lateral homogeneity of δ18O(melt). Worldwide, five other large-volume rhyolites, Lava Creek, Lower Bandelier, Fish Canyon, Cerro Galan, and Toba, exhibit equal δ18O(melt) values of earlier and later erupted portions in each of the these climactic caldera-forming eruptions. We interpret the large-scale δ18O homogeneity of BT and other large magma chambers as evidence

Progress in the Use of Isotopes: The Atomic Triad - Reactors, Radioisotopes and Radiation

DOE R&D Accomplishments Database

Libby, W. F.

1958-08-04

Recent years have seen a substantial growth in the use of isotopes in medicine, agriculture, and industry: up to the minute information on the production and use of isotopes in the U.S. is presented. The application of radioisotopes to industrial processes and manufacturing operations has expanded more rapidly than any one except its most ardent advocates expected. New uses and new users are numerous. The adoption by industry of low level counting techniques which make possible the use of carbon-14 and tritium in the control of industrial processes and in certain exploratory and research problems is perhaps most promising of current developments. The latest information on savings to industry will be presented. The medical application of isotopes has continued to develop at a rapid pace. The current trend appears to be in the direction of improvements in technique and the substitution of more effective isotopes for those presently in use. Potential and actual benefits accruing from the use of isotopes in agriculture are reviewed. The various methods of production of radioisotopes are discussed. Not only the present methods but also interesting new possibilities are covered. Although isotopes are but one of the many peaceful uses of the atom, it is the first to pay its way. (auth)

Multi-isotope tracers to investigate processes in the Elbe, Weser and Ems river catchment using B, Mo, Sr, and Pb isotope ratios assessed by MC ICP-MS

NASA Astrophysics Data System (ADS)

Irrgeher, Johanna; Reese, Anna; Zimmermann, Tristan; Prohaska, Thomas; Retzmann, Anika; Wieser, Michael E.; Zitek, Andreas; Proefrock, Daniel

2017-04-01

Environmental monitoring of complex ecosystems requires reliable sensitive techniques based on sound analytical strategies to identify the source, fate and sink of elements and matter. Isotopic signatures can serve to trace pathways by making use of specific isotopic fingermarks or to distinguish between natural and anthropogenic sources. The presented work shows the potential of using the isotopic variation of Sr, Pb (as well-established isotopic systems), Mo and B (as novel isotopic system) assessed by MC ICP-MS in water and sediment samples to study aquatic ecosystem transport processes. The isotopic variation of Sr, Pb, Mo and B was determined in different marine and estuarine compartments covering the catchment of the German Wadden Sea and its main tributaries, the Elbe, Weser and Ems River. The varying elemental concentrations, the complex matrix and the expected small variations in the isotopic composition required the development and application of reliable analytical measurement approaches as well as suited metrological data evaluation strategies. Aquatic isoscapes were created using ArcGIS® by relating spatial isotopic data with geographical and geological maps. The elemental and isotopic distribution maps show large variation for different parameters and also reflect the numerous impact factors (e.g. geology, anthropogenic sources) influencing the catchment area.

The Application of Methane Clumped Isotope Measurements to Determine the Source of Large Methane Seeps in Alaskan Lakes

NASA Astrophysics Data System (ADS)

Douglas, P. M.; Stolper, D. A.; Eiler, J. M.; Sessions, A. L.; Walter Anthony, K. M.

2014-12-01

Natural methane emissions from the Arctic present an important potential feedback to global warming. Arctic methane emissions may come from either active microbial sources or from deep fossil reservoirs released by the thawing of permafrost and melting of glaciers. It is often difficult to distinguish between and quantify contributions from these methane sources based on stable isotope data. Analyses of methane clumped isotopes (isotopologues with two or more rare isotopes such as 13CH3D) can complement traditional stable isotope-based classifications of methane sources. This is because clumped isotope abundances (for isotopically equilibrated systems) are a function of temperature and can be used to identify pathways of methane generation. Additionally, distinctive effects of mixing on clumped isotope abundances make this analysis valuable for determining the origins of mixed gasses. We find large variability in clumped isotope compositions of methane from seeps in several lakes, including thermokarst lakes, across Alaska. At Lake Sukok in northern Alaska we observe the emission of dominantly thermogenic methane, with a formation temperature of at least 100° C. At several other lakes we find evidence for mixing between thermogenic methane and biogenic methane that forms in low-temperature isotopic equilibrium. For example, at Eyak Lake in southeastern Alaska, analysis of three methane samples results in a distinctive isotopic mixing line between a high-temperature end-member that formed between 100-170° C, and a biogenic end-member that formed in isotopic equilibrium between 0-20° C. In this respect, biogenic methane in these lakes resembles observations from marine gas seeps, oil degradation, and sub-surface aquifers. Interestingly, at Goldstream Lake in interior Alaska, methane with strongly depleted clumped-isotope abundances, indicative of disequilibrium gas formation, is found, similar to observations from methanogen culture experiments.

Calcium Isotope Systematics During Development of the Domestic Chicken (Gallus gallus)

NASA Astrophysics Data System (ADS)

Wheatley, P. V.

2003-12-01

Calcium isotope distributions have been recognized as showing systematic and predictable fractionation in nature. However, most of the observed calcium isotope fractionation to date is due to biological processes. The presence of abundant amounts of calcium in mineralized tissues makes the isotopic system of calcium particularly valuable in biological and paleobiological questions involving biomineralization. In order to apply calcium isotope systematics to paleobiological questions the changes in the calcium isotope signatures of mineralized tissue in modern animals should be studied. My study observed the domestic chicken (Gallus gallus) through embryologic ontogeny. This was accomplished by obtaining fertilized eggs staged in a growth series from day 12 to day 20. The eggs were dissected and shell, embryonic bone, albumen, and yolk were analyzed in order to characterize the calcium isotopic composition of the individual components over the course of the growth series. Several systematic changes in the isotopic signatures of various tissues were observed during the course of the development of the embryos. In general, mineralization in biological systems preferentially partitions the lighter isotopes of calcium into hard parts. As a result of this fractionation during mineralization, partitioning of light isotopes of calcium into the mineralized tissues may result in residual tissues being enriched in the heavier isotopes as ontogeny progresses. Better understanding of the behavior of calcium in modern biological systems will improve its application to fossils and expand the number of paleobiological and evolutionary questions that can be addressed using calcium isotopic data.

Laser isotope separation of erbium and other isotopes

DOEpatents

Haynam, Christopher A.; Worden, Earl F.

1995-01-01

Laser isotope separation is accomplished using at least two photoionization pathways of an isotope simultaneously, where each pathway comprises two or more transition steps. This separation method has been applied to the selective photoionization of erbium isotopes, particularly for the enrichment of .sup.167 Er. The hyperfine structure of .sup.167 Er was used to find two three-step photoionization pathways having a common upper energy level.

Futuristic isotope hydrology in the Gulf region

NASA Astrophysics Data System (ADS)

Saravana Kumar, U.; Hadi, Khaled

2018-03-01

The Gulf region is one of the most water-stressed parts in the world. Water in the region is very scarce, shortage of supply and lacking of renewable water resources, while the demand for water is growing day by day. It is thus essential to implement modern approaches and technologies in addressing water-related issues. In this context, isotope hydrology will provide invaluable aid. Some of the most important areas of futuristic applications of isotope hydrology include evaluation of aquifer recharge, storage and their recovery system, understanding of dynamic changes due to long-term exploitation of the groundwater, development and management of shared groundwater aquifers, fresh groundwater discharge along the Arabian Gulf, identification and quantification of hydrocarbon contamination in groundwater; soil moisture and solute movement in unsaturated zone, paleoclimate reconstruction, etc. Literature survey suggests, in general, not many isotope studies on the above have been reported.

Applications of isotopes to tracing sources of solutes and water in shallow systems

USGS Publications Warehouse

Kendall, Carol; Krabbenhoft, David P.

1995-01-01

New awareness of the potential danger to water supplies posed by the use of agricultural chemicals has focused attention on the nature of groundwater recharge and the mobility of various solutes, especially nitrate and pesticides, in shallow systems. A better understanding of hydrologic flowpaths and solute sources is required to determine the potential impact of sources of contamination on water supplies, to develop management practices for preserving water quality, and to develop remediation plans for sites that are already contaminated. In many cases, environmental isotopes can be employed as 'surgical tools' for answering very specific questions about water and solute sources. Isotopic data can often provide more accurate information about the system than hydrologic measurements or complicated hydrologic models. This note focuses on practical and cost-effective examples of how naturally-occurring isotopes can be used to track water and solutes as they move through shallow systems.

Heavy atom labeled nucleotides for measurement of kinetic isotope effects.

PubMed

Weissman, Benjamin P; Li, Nan-Sheng; York, Darrin; Harris, Michael; Piccirilli, Joseph A

2015-11-01

Experimental analysis of kinetic isotope effects represents an extremely powerful approach for gaining information about the transition state structure of complex reactions not available through other methodologies. The implementation of this approach to the study of nucleic acid chemistry requires the synthesis of nucleobases and nucleotides enriched for heavy isotopes at specific positions. In this review, we highlight current approaches to the synthesis of nucleic acids enriched site specifically for heavy oxygen and nitrogen and their application in heavy atom isotope effect studies. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of phenylalanine isotope ratio enrichment by liquid chromatography/time- of-flight mass spectrometry.

PubMed

Wu, Zhanpin; Zhang, Xiao-Jun; Cody, Robert B; Wolfe, Robert R

2004-01-01

The application of time-of-flight mass spectrometry to isotope ratio measurements has been limited by the relatively low dynamic range of the time-to-digital converter detectors available on commercial LC/ToF-MS systems. Here we report the measurement of phenylalanine isotope ratio enrichment by using a new LC/ToF-MS system with wide dynamic range. Underivatized phenylalanine was injected onto a C18 column directly with 0.1% formic acid/acetonitrile as the mobile phase. The optimal instrument parameters for the time-of-flight mass spectrometer were determined by tuning the instrument with a phenylalanine standard. The accuracy of the isotope enrichment measurement was determined by the injection of standard solutions with known isotope ratios ranging from 0.02% to 9.2%. A plot of the results against the theoretical values gave a linear curve with R2 of 0.9999. The coefficient of variation for the isotope ratio measurement was below 2%. The method is simple, rapid, and accurate and presents an attractive alternative to traditional GC/MS applications.

Energy Transition Initiative: Island Energy Snapshot - American Samoa; U.S. Department of Energy (DOE), NREL (National Renewable Energy Laboratory)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2015-06-01

This profile provides a snapshot of the energy landscape of American Samoa, the southernmost territory of the United States. American Samoa’s residential electricity rates are approximately $0.29 U.S. dollars (USD) per kilowatt-hour (kWh), more than twice the average U.S. residential rate of $0.13 USD/kWh.

The Nation's Report Card Reading 2009 Trial Urban District Snapshot Report. Austin Independent School District. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each district that participated in the National Assessment of Educational Progress (NAEP) 2009 Trial Urban District Assessment in reading receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Austin Independent School District's student achievement in reading. In 2009,…

The Nation's Report Card Reading 2009 Trial Urban District Snapshot Report. Austin Independent School District. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each district that participated in the National Assessment of Educational Progress (NAEP) 2009 Trial Urban District Assessment in reading receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for Austin Independent School District's student achievement in reading. In 2009,…

Laser isotope separation of erbium and other isotopes

DOEpatents

Haynam, C.A.; Worden, E.F.

1995-08-22

Laser isotope separation is accomplished using at least two photoionization pathways of an isotope simultaneously, where each pathway comprises two or more transition steps. This separation method has been applied to the selective photoionization of erbium isotopes, particularly for the enrichment of {sup 167}Er. The hyperfine structure of {sup 167}Er was used to find two three-step photoionization pathways having a common upper energy level. 3 figs.

Raman scattering method and apparatus for measuring isotope ratios and isotopic abundances

DOEpatents

Harney, Robert C.; Bloom, Stewart D.

1978-01-01

Raman scattering is used to measure isotope ratios and/or isotopic abundances. A beam of quasi-monochromatic photons is directed onto the sample to be analyzed, and the resulting Raman-scattered photons are detected and counted for each isotopic species of interest. These photon counts are treated mathematically to yield the desired isotope ratios or isotopic abundances.

Application of non-lethal stable isotope analysis to assess feeding patterns of juvenile pallid sturgeon Scaphirhynchus albus: a comparison of tissue types and sample preservation methods

USGS Publications Warehouse

Andvik, R.T.; VanDeHey, J.A.; Fincel, M.J.; French, William E.; Bertrand, K.N.; Chipps, Steven R.; Klumb, Robert A.; Graeb, B.D.S.

2010-01-01

Traditional techniques for stable isotope analysis (SIA) generally require sacrificing animals to collect tissue samples; this can be problematic when studying diets of endangered species such as the pallid sturgeon Scaphirhynchus albus. Our objectives were to (i) determine if pectoral fin tissue (non-lethal) could be a substitute for muscle tissue (lethal) in SIA of juvenile pallid sturgeon, and (ii) evaluate the influence of preservation techniques on stable isotope values. In the laboratory, individual juvenile pallid sturgeon were held for up to 186 day and fed chironomids, fish, or a commercially available pellet diet. Significant, positive relationships (r² ≥ 0.8) were observed between fin and muscle tissues for both δ15N and δ13C; in all samples isotopes were enriched in fins compared to muscle tissue. Chironomid and fish based diets of juvenile pallid sturgeon were distinguishable for fast growing fish (0.3 mm day−1) using stable δ15N and δ13C isotopes. Frozen and preserved fin tissue δ15N isotopes were strongly related (r2 = 0.89) but δ13C isotopes were weakly related (r2 = 0.16). Therefore, freezing is recommended for preservation of fin clips to avoid the confounding effect of enrichment by ethanol. This study demonstrates the utility of a non-lethal technique to assess time integrated food habits of juvenile pallid sturgeon and should be applicable to other threatened or endangered species.

Statistical clumped isotope signatures

PubMed Central

Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

2016-01-01

High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

Applications of Cavity Ring-Down Spectroscopy (CRDS) to Analysis of Carbon Stable Isotope Composition of Groundwater

NASA Astrophysics Data System (ADS)

Jeong, T.; Woo, N. C.; Choi, H.

2014-12-01

Carbon Capture and Storage (CCS) has been considered as an effective strategy to reduce atmospheric carbon dioxide (CO2) concentration. However, unintended leakage of CO2 leakage from storage sites could occur through highly permeable conduits such as fractures in low-K formations during the injection and storage of SCCO2 (supercritical phase CO2). Therefore, prediction and detection of CO2 leakage and relevant analysis of carbon isotope are crucial to assure environmental and public safety. Until recently, Isotope Ratio Mass Spectrometry (IRMS) has been utilized to measure the stable isotope ratio of water. However, IRMS is time-consuming operation due to complicated pretreatment, and thus not a practical methodology under field conditions. Carbon Isotope Analyzer (CCIA), which is a kind of Cavity Ring-Down Spectroscopy (CRDS) and has a wide measurement range from 300 to 25000 ppmv, can facilitate the rate of measurements up to 1 Hz by using continuous flow method so that it can be readily applied to field. In this study, carbon stable isotope ratio of groundwater will be analyzed using CCIA. Then, the CCIA results will be compared with IRMS to validate its accuracy and stability. This research will provide an appropriate method for analyzing carbon stable isotope in groundwater, using a continuous flow mode.

Isotope ratio mass spectrometry in nutrition research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luke, A.H.

Many of the biochemical pathways and processes that form the foundation of modern nutrition research was elucidated using stable isotopes as physiological tracers. Since the discovery of stable isotopes, improvements and innovations in mass spectrometry and chromatography have led to greatly expanded applications. This research project was designed to evaluate gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) as a tool for isotopic tracer studies and to delineate the operational parameters for the analysis of {sup 13}C-labeled cholesterol, leucine and {alpha}-ketoisocaproate. The same isotope ratio mass spectrometer was then used as the base instrument for the ratio mass spectrometer was then usedmore » as the base instrument for the development of two additional inlet systems: a continuous-flow inlet for the analyses of {sup 13}C and {sup 18}O as CO{sub 2} and a filament inlet for on-line combustion and isotopic analysis of non-volatile organic compounds. Each of these three inlets was evaluated and their utility in nutrition research illustrated. GC/C/IRMS was used to analyze cholesterol, leucine and {alpha}-ketoisocaproate with good accuracy, precision and little isotopic memory. For all three compounds the detection limits achieved well surpassed currently used technologies. For compounds that can be well separated by GC, GC/C/IRMS is a valuable analytical tool. The continuous-flow inlet provided good accuracy and precision for measurements of {sup 13}CO{sub 2} from breath tests and {sup 18}O as CO{sub 2} from total energy expenditure tests. Most importantly, the continuous-flow inlet increased sample throughput by at least a factor of three over conventional analytical techniques. The filament inlet provided accurate and precise {sup 13}C ratio measurements of both natural abundance and enriched standards of non-volatile organic compounds of physiological interest.« less

A Review of Out-of-School Time Program Quasi-Experimental and Experimental Evaluation Results. Out-of-School Time Evaluation Snapshot.

ERIC Educational Resources Information Center

Little, Priscilla M. D.; Harris, Erin

As the amount of resources allocated to out-of-school (OST) programming and policymakers' demands for research-based results increase, there is increasing interest in rigorous research designs to examine OST program outcomes. This issue of "Out-of-School Time Evaluation Snapshots" reviews 27 quasi-experimental and experimental OST…

Final report of the key comparison CCQM-K98: Pb isotope amount ratios in bronze

NASA Astrophysics Data System (ADS)

Vogl, Jochen; Yim, Yong-Hyeon; Lee, Kyoung-Seok; Goenaga-Infante, Heidi; Malinowskiy, Dmitriy; Ren, Tongxiang; Wang, Jun; Vocke, Robert D., Jr.; Murphy, Karen; Nonose, Naoko; Rienitz, Olaf; Noordmann, Janine; Näykki, Teemu; Sara-Aho, Timo; Ari, Betül; Cankur, Oktay

2014-01-01

Isotope amount ratios are proving useful in an ever increasing array of applications that range from studies unravelling transport processes, to pinpointing the provenance of specific samples as well as trace element quantification by using isotope dilution mass spectrometry (IDMS). These expanding applications encompass fields as diverse as archaeology, food chemistry, forensic science, geochemistry, medicine and metrology. However, to be effective tools, the isotope ratio data must be reliable and traceable to enable the comparability of measurement results. The importance of traceability and comparability in isotope ratio analysis has already been recognized by the Inorganic Analysis Working Group (IAWG) within the CCQM. While the requirements for isotope ratio accuracy and precision in the case of IDMS are generally quite modest, 'absolute' Pb isotope ratio measurements for geochemical applications as well as forensic provenance studies require Pb isotope ratio measurements of the highest quality. To support present and future CMCs on isotope ratio determinations, a key comparison was urgently needed and therefore initiated at the IAWG meeting in Paris in April 2011. The analytical task within such a comparison was decided to be the measurement of Pb isotope amount ratios in water and bronze. Measuring Pb isotope amount ratios in an aqueous Pb solution tested the ability of analysts to correct for any instrumental effects on the measured ratios, while the measurement of Pb isotope amount ratios in a metal matrix sample provided a real world test of the whole chemical and instrumental procedure. A suitable bronze material with a Pb mass fraction between 10 and 100 mg•kg-1 and a high purity solution of Pb with a mass fraction of approximately 100 mg•kg-1 was available at the pilot laboratory (BAM), both offering a natural-like Pb isotopic composition. The mandatory measurands, the isotope amount ratios n(206Pb)/n(204Pb), n(207Pb)/n(204Pb) and n(208Pb)/n(204Pb

Stable isotope discrimination factors and between-tissue isotope comparisons for bone and skin from captive and wild green sea turtles (Chelonia mydas).

PubMed

Turner Tomaszewicz, Calandra N; Seminoff, Jeffrey A; Price, Mike; Kurle, Carolyn M

2017-11-30

The ecological application of stable isotope analysis (SIA) relies on taxa- and tissue-specific stable carbon (Δ 13 C) and nitrogen (Δ 15 N) isotope discrimination factors, determined with captive animals reared on known diets for sufficient time to reflect dietary isotope ratios. However, captive studies often prohibit lethal sampling, are difficult with endangered species, and reflect conditions not experienced in the wild. We overcame these constraints and determined the Δ 13 C and Δ 15 N values for skin and cortical bone from green sea turtles (Chelonia mydas) that died in captivity and evaluated the utility of a mathematical approach to predict discrimination factors. Using stable carbon (δ 13 C values) and nitrogen (δ 15 N values) isotope ratios from captive and wild turtles, we established relationships between bone stable isotope (SI) ratios and those from skin, a non-lethally sampled tissue, to facilitate comparisons of SI ratios among studies using multiple tissues. The mean (±SD) Δ 13 C and Δ 15 N values (‰) between skin and bone from captive turtles and their diet (non-lipid-extracted) were 2.3 ± 0.3 and 4.1 ± 0.4 and 2.1 ± 0.6 and 5.1 ± 1.1, respectively. The mathematically predicted Δ 13 C and Δ 15 N values were similar (to within 1‰) to the experimentally derived values. The mean δ 15 N values from bone were higher than those from skin for captive (+1.0 ± 0.9‰) and wild (+0.8 ± 1.0‰) turtles; the mean δ 13 C values from bone were lower than those from skin for wild turtles (-0.6 ± 0.9‰), but the same as for captive turtles. We used linear regression equations to describe bone vs skin relationships and create bone-to-skin isotope conversion equations. For sea turtles, we provide the first (a) bone-diet SI discrimination factors, (b) comparison of SI ratios from individual-specific bone and skin, and (c) evaluation of the application of a mathematical approach to predict stable isotope discrimination factors. Our approach

Rare isotope accelerator project in Korea and its application to high energy density sciences

NASA Astrophysics Data System (ADS)

Chung, M.; Chung, Y. S.; Kim, S. K.; Lee, B. J.; Hoffmann, D. H. H.

2014-01-01

As a national science project, the Korean government has recently established the Institute for Basic Science (IBS) with the goal of conducting world-class research in basic sciences. One of the core facilities for the IBS will be the rare isotope accelerator which can produce high-intensity rare isotope beams to investigate the fundamental properties of nature, and also to support a broad research program in material sciences, medical and biosciences, and future nuclear energy technologies. The construction of the accelerator is scheduled to be completed by approximately 2017. The design of the accelerator complex is optimized to deliver high average beam current on targets, and to maximize the production of rare isotope beams through the simultaneous use of Isotope Separation On-Line (ISOL) and In-Flight Fragmentation (IFF) methods. The proposed accelerator is, however, not optimal for high energy density science, which usually requires very high peak currents on the target. In this study, we present possible beam-plasma experiments that can be done within the scope of the current accelerator design, and we also investigate possible future extension paths that may enable high energy density science with intense pulsed heavy ion beams.

A snapshot of global health education at North American universities.

PubMed

Lencucha, Raphael; Mohindra, Katia

2014-03-01

Global health education is becoming increasingly prominent in North America. It is widely agreed upon that global health is an important aspect of an education in the health sciences and increasingly in other disciplines such as law, economics and political science. There is currently a paucity of studies examining the content of global health courses at the post-secondary level. The purpose of our research is to identify the content areas being covered in global health curricula in North American universities, as a first step in mapping global health curricula across North America. We collected 67 course syllabi from 31 universities and analyzed the topics covered in the course. This snapshot of global health education will aid students searching for global health content, as well as educators and university administrators who are developing or expanding global health programs in Canada and the United States.

Developing the Molybdenum Isotopic Proxy in Marine Barite

NASA Astrophysics Data System (ADS)

Erhardt, A. M.; Paytan, A.; Aggarwal, J.

2006-12-01

Molybdenum isotope ratios in seawater fluctuate in response to changing redox conditions and can provide clues into the degree of global ocean anoxia. The isotopic ratio of molybdenum has been shown to be sensitive to the relative proportion of oxic, suboxic, and euxinic environments. Deposition in oxic environments is isotopically light (~ -1.6‰ for δ^{97/95}Mo) relative to an average crustal source (0‰). Conversely, euxinic environments have been shown to be consistently heavier (~1.3‰) than the oxic sink through time, with suboxic sediments falling between these two signals. Shifts in the relative proportion of each sink, relative to a constant source, would alter the isotopic ratio of seawater over long time scales. Previously, this seawater value, and hence the degree of global anoxia, could only be inferred through mass balance calculations. We seek to quantify the isotopic signature of seawater though time using a phase that directly records this ratio. Marine barite precipitates inorganically in the water column directly from seawater, potentially providing a direct record of seawater characteristics. Molybdenum is a trace constituent of barite, with the molybdate ion substituting for sulfate at concentrations of about 1 ppm. To accurately determine the molybdenum isotopic ratio at these low concentrations (<15 ng per sample), modifications to existing measurement techniques are required. We will present the variations made to existing separation and mass-spectrometry techniques and the calibration of these new methods. The modifications were undertaken to reduce molybdenum blank to below 1 ng per analysis, to quantitatively remove interfering zirconium and to measure precise and reproducible isotope values. Preliminary data will be presented to illustrate potential applications for this new paleoredox proxy. This technique will allow for the measurement of molybdenum isotopic ratios at low concentrations, expanding the breath of compounds and

Modeling of isotope fractionation at the catchment scale: How promising is compound specific isotope analysis (CSIA) as a tool for analyzing diffuse pollution by agrochemicals?

NASA Astrophysics Data System (ADS)

Lutz, S. R.; van Meerveld, H. J.; Waterloo, M. J.; Broers, H. P.; van Breukelen, B. M.

2012-04-01

Concentration measurements are indispensable for the assessment of subsurface and surface water pollution by agrochemicals such as pesticides. However, monitoring data is often ambiguous and easily misinterpreted as a decrease in concentration could be caused by transformation, dilution or changes in the application of the pesticide. In this context, compound specific isotope analysis (CSIA) has recently emerged as a complementary monitoring technique. It is based on the measurement of the isotopic composition (e.g. δ13C and δ2H) of the contaminant. Since transformation processes are likely accompanied by isotope fractionation, thus a change in this composition, CSIA offers the opportunity to gain additional knowledge about transport and degradation processes as well as to track pollutants back to their sources. Isotopic techniques have not yet been applied in a comprehensive way in the analysis of catchment-wide organic pollution. We therefore incorporated fractionation processes associated with the fate of pesticides into the numerical flow and solute transport model HydroGeoSphere in order to assess the feasibility of CSIA within the context of catchment monitoring. The model was set up for a hypothetical hillslope transect which drains into a river. Reactive solute transport was driven by two pesticides applications within one year and actual data for rainfall and potential evapotranspiration from a meteorological station in the Netherlands. Degradation of the pesticide was assumed to take place at a higher rate under the prevailing oxic conditions in the topsoil than in deeper, anoxic subsurface layers. In terms of CSIA, these two degradation pathways were associated with different strengths of isotope fractionation for both hydrogen and carbon atoms. By simulating changes in δ13C and δ2H, the share of the oxic and the anoxic reaction on the overall degradation could be assessed. Model results suggest that CSIA is suitable for assessing degradation of

Simultaneous determination of the quantity and isotopic ratios of uranium in individual micro-particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS).

PubMed

Park, Jong-Ho; Choi, Eun-Ju

2016-11-01

A method to determine the quantity and isotopic ratios of uranium in individual micro-particles simultaneously by isotope dilution thermal ionization mass spectrometry (ID-TIMS) has been developed. This method consists of sequential sample and spike loading, ID-TIMS for isotopic measurement, and application of a series of mathematical procedures to remove the contribution of uranium in the spike. The homogeneity of evaporation and ionization of uranium content was confirmed by the consistent ratio of n((233)U)/n((238)U) determined by TIMS measurements. Verification of the method was performed using U030 solution droplets and U030 particles. Good agreements of resulting uranium quantity, n((235)U)/n((238)U), and n((236)U)/n((238)U) with the estimated or certified values showed the validity of this newly developed method for particle analysis when simultaneous determination of the quantity and isotopic ratios of uranium is required. Copyright © 2016 Elsevier B.V. All rights reserved.

Gravitational lensing of quasars as seen by the Hubble Space Telescope Snapshot Survey

NASA Technical Reports Server (NTRS)

Maoz, D.; Bahcall, J. N.; Doxsey, R.; Schneider, D. P.; Bahcall, N. A.; Lahav, O.; Yanny, B.

1992-01-01

Results from the ongoing HST Snapshot Survey are presented, with emphasis on 152 high-luminosity, z greater than 1 quasars. One quasar among those observed, 1208 + 1011, is a candidate lens system with subarcsecond image separation. Six other quasars have point sources within 6 arcsec. Ground-based observations of five of these cases show that the companion point sources are foreground Galactic stars. The predicted lensing frequency of the sample is calculated for a variety of cosmological models. The effect of uncertainties in some of the observational parameters upon the predictions is discussed. No correlation of the drift rate with time, right ascension, declination, or point error is found.

Synthesis of l-cysteine derivatives containing stable sulfur isotopes and application of this synthesis to reactive sulfur metabolome.

PubMed

Ono, Katsuhiko; Jung, Minkyung; Zhang, Tianli; Tsutsuki, Hiroyasu; Sezaki, Hiroshi; Ihara, Hideshi; Wei, Fan-Yan; Tomizawa, Kazuhito; Akaike, Takaaki; Sawa, Tomohiro

2017-05-01

Cysteine persulfide is an L-cysteine derivative having one additional sulfur atom bound to a cysteinyl thiol group, and it serves as a reactive sulfur species that regulates redox homeostasis in cells. Here, we describe a rapid and efficient method of synthesis of L-cysteine derivatives containing isotopic sulfur atoms and application of this method to a reactive sulfur metabolome. We used bacterial cysteine syntheses to incorporate isotopic sulfur atoms into the sulfhydryl moiety of L-cysteine. We cloned three cysteine synthases-CysE, CysK, and CysM-from the Gram-negative bacterium Salmonella enterica serovar Typhimurium LT2, and we generated their recombinant enzymes. We synthesized 34 S-labeled L-cysteine from O-acetyl-L-serine and 34 S-labeled sodium sulfide as substrates for the CysK or CysM reactions. Isotopic labeling of L-cysteine at both sulfur ( 34 S) and nitrogen ( 15 N) atoms was also achieved by performing enzyme reactions with 15 N-labeled L-serine, acetyl-CoA, and 34 S-labeled sodium sulfide in the presence of CysE and CysK. The present enzyme systems can be applied to syntheses of a series of L-cysteine derivatives including L-cystine, L-cystine persulfide, S-sulfo-L-cysteine, L-cysteine sulfonate, and L-selenocystine. We also prepared 34 S-labeled N-acetyl-L-cysteine (NAC) by incubating 34 S-labeled L-cysteine with acetyl coenzyme A in test tubes. Tandem mass spectrometric identification of low-molecular-weight thiols after monobromobimane derivatization revealed the endogenous occurrence of NAC in the cultured mammalian cells such as HeLa cells and J774.1 cells. Furthermore, we successfully demonstrated, by using 34 S-labeled NAC, metabolic conversion of NAC to glutathione and its persulfide, via intermediate formation of L-cysteine, in the cells. The approach using isotopic sulfur labeling combined with mass spectrometry may thus contribute to greater understanding of reactive sulfur metabolome and redox biology. Copyright © 2017 Elsevier Inc

Isotope analysis in the transmission electron microscope.

PubMed

Susi, Toma; Hofer, Christoph; Argentero, Giacomo; Leuthner, Gregor T; Pennycook, Timothy J; Mangler, Clemens; Meyer, Jannik C; Kotakoski, Jani

2016-10-10

The Ångström-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This can unambiguously resolve the chemical structure of materials, but not their isotopic composition. Here we differentiate between two isotopes of the same element by quantifying how likely the energetic imaging electrons are to eject atoms. First, we measure the displacement probability in graphene grown from either 12 C or 13 C and describe the process using a quantum mechanical model of lattice vibrations coupled with density functional theory simulations. We then test our spatial resolution in a mixed sample by ejecting individual atoms from nanoscale areas spanning an interface region that is far from atomically sharp, mapping the isotope concentration with a precision better than 20%. Although we use a scanning instrument, our method may be applicable to any atomic resolution transmission electron microscope and to other low-dimensional materials.

Development of fast-release solid catchers for rare isotopes

NASA Astrophysics Data System (ADS)

Nolen, Jerry; Greene, John; Elam, Jeffrey; Mane, Anil; Sampathkumaran, Uma; Winter, Raymond; Hess, David; Mushfiq, Mohammad; Stracener, Daniel; Wiendenhoever, Ingo

2015-04-01

Porous solid catchers of rare isotopes are being developed for use at high power heavy ion accelerator facilities such as RIKEN, FRIB, and RISP. Compact solid catchers are complementary to helium gas catchers for parasitic harvesting of rare isotopes in the in-flight separators. They are useful for short lived isotopes for basic nuclear physics research and longer-lived isotopes for off-line applications. Solid catchers can operate effectively with high intensity secondary beams, e.g. >> 1E10 atoms/s with release times as short as 10-100 milliseconds. A new method using a very sensitive and efficient RGA has been commissioned off-line at Argonne and is currently being shipped to Florida State University for in-beam measurements of the release curves using stable beams. The same porous solid catcher technology is also being evaluated for use in targets for the production of medical isotopes such as 211-At. Research supported by the U.S. DOE Office of Nuclear Physics under the SBIR Program and Contract # DE-AC02-06CH11357 and a University of Chicago Comprehensive Cancer Center/ANL Pilot Project.

ISOTOPE CONVERSION DEVICE

DOEpatents

Wigner, E.P.; Young, G.J.; Ohlinger, L.A.

1957-12-01

This patent relates to nuclear reactors of tbe type utilizing a liquid fuel and designed to convert a non-thermally fissionable isotope to a thermally fissionable isotope by neutron absorption. A tank containing a reactive composition of a thermally fissionable isotope dispersed in a liquid moderator is disposed within an outer tank containing a slurry of a non-thermally fissionable isotope convertible to a thermally fissionable isotope by neutron absorption. A control rod is used to control the chain reaction in the reactive composition and means are provided for circulating and cooling the reactive composition and slurry in separate circuits.

Physics of the Isotopic Dependence of Galactic Cosmic Ray Fluence Behind Shielding

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.; Saganti, Premkumar B.; Hu, Xiao-Dong; Kim, Myung-Hee Y.; Cleghorn, Timothy F.; Wilson, John W.; Tripathi, Ram K.; Zeitlin, Cary J.

2003-01-01

For over 25 years, NASA has supported the development of space radiation transport models for shielding applications. The NASA space radiation transport model now predicts dose and dose equivalent in Earth and Mars orbit to an accuracy of plus or minus 20%. However, because larger errors may occur in particle fluence predictions, there is interest in further assessments and improvements in NASA's space radiation transport model. In this paper, we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR) and the isotopic dependence of nuclear fragmentation cross-sections on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. Using NASA's quantum multiple-scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, we study the effect of the isotopic dependence of the primary GCR composition and secondary nuclei on shielding calculations. The QMSFRG is shown to accurately describe the iso-spin dependence of nuclear fragmentation. The principal finding of this study is that large errors (plus or minus 100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotope grid (approximately 170 ions) to ones that use a reduced isotope grid, for example the 59 ion-grid used in the HZETRN code in the past, however less significant errors (less than 20%) occur in the elemental-fluence spectra. Because a complete isotope grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies.

A Little More Madness in Our Methods? A Snapshot of How the Educational Leadership, Management and Administration Field Conducts Research

ERIC Educational Resources Information Center

Thomson, Pat

2017-01-01

The field of educational leadership, management and administration (ELMA) uses methods drawn primarily from cognate educational disciplines. But does this matter? This paper explores the methods used in recently published papers through a snapshot of six issues of six ELMA journals. The analysis showed a preponderance of survey, interview and case…

Precise and traceable carbon isotope ratio measurements by multicollector ICP-MS: what next?

PubMed

Santamaria-Fernandez, Rebeca

2010-06-01

This article reviews recent developments in the use of multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) to provide high-precision carbon isotope ratio measurements. MC-ICP-MS could become an alternative method to isotope ratio mass spectrometry (IRMS) for rapid carbon isotope ratio determinations in organic compounds and characterisation and certification of isotopic reference materials. In this overview, the advantages, drawbacks and potential of the method for future applications are critically discussed. Furthermore, suggestions for future improvements in terms of precision and sensitivity are made. No doubt, this is an exciting analytical challenge and, as such, hurdles will need to be cleared.

Joint Application of Concentrations and Isotopic Signatures to Investigate the Global Atmospheric Carbon Monoxide Budget: Inverse Modeling Approach

NASA Astrophysics Data System (ADS)

Park, K.; Emmons, L. K.; Mak, J. E.

2007-12-01

Carbon monoxide is not only an important component for determining the atmospheric oxidizing capacity but also a key trace gas in the atmospheric chemistry of the Earth's background environment. The global CO cycle and its change are closely related to both the change of CO mixing ratio and the change of source strength. Previously, to estimate the global CO budget, most top-down estimation techniques have been applied the concentrations of CO solely. Since CO from certain sources has a unique isotopic signature, its isotopes provide additional information to constrain its sources. Thus, coupling the concentration and isotope fraction information enables to tightly constrain CO flux by its sources and allows better estimations on the global CO budget. MOZART4 (Model for Ozone And Related chemical Tracers), a 3-D global chemical transport model developed at NCAR, MPI for meteorology and NOAA/GFDL and is used to simulate the global CO concentration and its isotopic signature. Also, a tracer version of MOZART4 which tagged for C16O and C18O from each region and each source was developed to see their contributions to the atmosphere efficiently. Based on the nine-year- simulation results we analyze the influences of each source of CO to the isotopic signature and the concentration. Especially, the evaluations are focused on the oxygen isotope of CO (δ18O), which has not been extensively studied yet. To validate the model performance, CO concentrations and isotopic signatures measured from MPI, NIWA and our lab are compared to the modeled results. The MOZART4 reproduced observational data fairly well; especially in mid to high latitude northern hemisphere. Bayesian inversion techniques have been used to estimate the global CO budget with combining observed and modeled CO concentration. However, previous studies show significant differences in their estimations on CO source strengths. Because, in addition to the CO mixing ratio, isotopic signatures are independent

Joint Application of Concentrations and Isotopic Signatures to Investigate the Global Atmospheric Carbon Monoxide Budget: Inverse Modeling Approach

NASA Astrophysics Data System (ADS)

Park, K.; Mak, J. E.; Emmons, L. K.

2008-12-01

Carbon monoxide is not only an important component for determining the atmospheric oxidizing capacity but also a key trace gas in the atmospheric chemistry of the Earth's background environment. The global CO cycle and its change are closely related to both the change of CO mixing ratio and the change of source strength. Previously, to estimate the global CO budget, most top-down estimation techniques have been applied the concentrations of CO solely. Since CO from certain sources has a unique isotopic signature, its isotopes provide additional information to constrain its sources. Thus, coupling the concentration and isotope fraction information enables to tightly constrain CO flux by its sources and allows better estimations on the global CO budget. MOZART4 (Model for Ozone And Related chemical Tracers), a 3-D global chemical transport model developed at NCAR, MPI for meteorology and NOAA/GFDL and is used to simulate the global CO concentration and its isotopic signature. Also, a tracer version of MOZART4 which tagged for C16O and C18O from each region and each source was developed to see their contributions to the atmosphere efficiently. Based on the nine-year-simulation results we analyze the influences of each source of CO to the isotopic signature and the concentration. Especially, the evaluations are focused on the oxygen isotope of CO (δ18O), which has not been extensively studied yet. To validate the model performance, CO concentrations and isotopic signatures measured from MPI, NIWA and our lab are compared to the modeled results. The MOZART4 reproduced observational data fairly well; especially in mid to high latitude northern hemisphere. Bayesian inversion techniques have been used to estimate the global CO budget with combining observed and modeled CO concentration. However, previous studies show significant differences in their estimations on CO source strengths. Because, in addition to the CO mixing ratio, isotopic signatures are independent tracers

Electron linac for medical isotope production with improved energy efficiency and isotope recovery

DOEpatents

Noonan, John; Walters, Dean; Virgo, Matt; Lewellen, John

2015-09-08

A method and isotope linac system are provided for producing radio-isotopes and for recovering isotopes. The isotope linac is an energy recovery linac (ERL) with an electron beam being transmitted through an isotope-producing target. The electron beam energy is recollected and re-injected into an accelerating structure. The ERL provides improved efficiency with reduced power requirements and provides improved thermal management of an isotope target and an electron-to-x-ray converter.

13C metabolic flux analysis: optimal design of isotopic labeling experiments.

PubMed

Antoniewicz, Maciek R

2013-12-01

Measuring fluxes by 13C metabolic flux analysis (13C-MFA) has become a key activity in chemical and pharmaceutical biotechnology. Optimal design of isotopic labeling experiments is of central importance to 13C-MFA as it determines the precision with which fluxes can be estimated. Traditional methods for selecting isotopic tracers and labeling measurements did not fully utilize the power of 13C-MFA. Recently, new approaches were developed for optimal design of isotopic labeling experiments based on parallel labeling experiments and algorithms for rational selection of tracers. In addition, advanced isotopic labeling measurements were developed based on tandem mass spectrometry. Combined, these approaches can dramatically improve the quality of 13C-MFA results with important applications in metabolic engineering and biotechnology. Copyright © 2013 Elsevier Ltd. All rights reserved.

Stable Isotope Mapping of Alaskan Grasses and Marijuana

NASA Astrophysics Data System (ADS)

Booth, A. L.; Wooller, M. J.

2008-12-01

The spatial variation of isotope signatures in organic material is a useful forensic tool, particularly when applied to the task of tracking the production and distribution of plant-derived illicit drugs. In order to identify the likely grow-locations of drugs such as marijuana from unknown locations (i.e., confiscated during trafficking), base isotope maps are needed that include measurements of plants from known grow-locations. This task is logistically challenging in remote, large regions such as Alaska. We are therefore investigating the potential of supplementing our base (marijuana) isotope maps with data derived from other plants from known locations and with greater spatial coverage in Alaska. These currently include >150 samples of modern C3 grasses (Poaceae) as well as marijuana samples (n = 18) from known grow-locations across the state. We conducted oxygen, carbon and nitrogen stable isotope analyses of marijuana and grasses (Poaceae). Poaceae samples were obtained from the University of Alaska Fairbanks (UAF) Museum of the North herbarium collection, originally collected by field botanists from around Alaska. Results indicate that the oxygen isotopic composition of these grasses range from 10‰ to 30‰, and broadly mirror the spatial pattern of water isotopes in Alaska. Our marijuana samples were confiscated around the state of Alaska and supplied to us by the UAF Police Department. δ13C, δ15N and δ18O values exhibit geographic patterns similar to the modern grasses, but carbon and nitrogen isotopes of some marijuana plants appear to be influenced by additional factors related to indoor growing conditions (supplementary CO2 sources and the application of organic fertilizer). As well as providing a potential forensic resource, our Poaceae isotope maps could serve additional value by providing resources for studying ecosystem nutrient cycling, for tracing natural ecological processes (i.e., animal migration and food web dynamics) and providing

Application of stable isotope (δ13C and δ18O) composition of mollusc shells in palaeolimnological studies - possibilities and limitations

NASA Astrophysics Data System (ADS)

Apolinarska, Karina; Pełechaty, Mariusz; Kossler, Annette; Pronin, Eugeniusz; Noskowiak, Daria

2017-04-01

Carbon (δ13C) and oxygen (δ18O) stable isotope analyses are among the standard methods applied in the studies of past environment, including climate. In lacustrine sediments, δ13C and δ18O values can be measured in fine carbonate fraction (carbonate mud), in charophyte encrustations, ostracod carapaces and mollusc shells. Application of the stable isotope record of each of the above-mentioned components of the lake sediment requires knowledge about possibilities and limitations of the method. The present research discusses the most important results of the studies carried out between 2011 and 2013, concentrated on the stable isotope composition of snail shells, primarily, the species commonly preserved in central European Quaternary lacustrine sediments. The stable isotope studies involved also, the zebra mussel (Dreissena polymorpha), one of the most invasive freshwater species in the world. The research involved shell isotope studies of both recent (Apolinarska, 2013; Apolinarska et al., 2016; Apolinarska and Pełechaty, in press) and fossil molluscs derived from the Holocene sediments (Apolinarska et al., 2015a, b). Shell δ13C values were species-specific and among the gastropods studied the same order of species from the most to the least 13C-depleted was observed at all sites sampled. Shell δ18O values were more uniform. The wide range of δ13C and δ18O values were observed in population and subpopulation, i.e. when live snails were sampled live from restricted area within the lake littoral zone. Carbon and oxygen stable isotope values of the mono-specific shells sampled from 1 cm thick sediment samples were highly variable. Those intra-specific differences (n=20) were as large as several permill. Such significant variability in δ13C and δ18O values indicates that stable isotope composition of single shells is unlikely to be representative of the sediment sample. In conclusion, samples of freshwater molluscs for stable isotope analyses should be

Snapshots of simulation: creative strategies used by Australian educators to enhance simulation learning experiences for nursing students.

PubMed

McAllister, Margaret; Levett-Jones, Tracy; Downer, Teresa; Harrison, Penelope; Harvey, Theresa; Reid-Searl, Kerry; Lynch, Kathy; Arthur, Carol; Layh, Janice; Calleja, Pauline

2013-11-01

Simulation in nursing is a flourishing area for nurse educators' practice. Defined as learning that amplifies, mimics or replaces real-life clinical situations, simulation aims to give students opportunity to reason through a clinical problem and make decisions, without the potential for harming actual patients. Educators in nursing are contributing to simulation learning in diverse and creative ways. Yet much of their craft is not being widely disseminated because educators are not always confident in publishing their work. This paper aims to stimulate creative development in simulation by providing short summaries, or snapshots, of diverse approaches that nurse educators are using. The objective is to inspire others to share other ideas in development or in practice that are improving learning for nursing students and practitioners, so that simulation scholarship is advanced. The snapshots presented range from approaches that: better support educators to attend to the whole process of simulation education, give students quick access to short skill-based videos, orientate students to the laboratory environment, harness the power of the group to develop documentation skills, use simulation to enrich lectures, develop multidisciplinary knowledge, and finally, which teach therapeutic communication with children in a fun and imaginative way. Copyright © 2013 Elsevier Ltd. All rights reserved.

Direct uranium isotope ratio analysis of single micrometer-sized glass particles

PubMed Central

Kappel, Stefanie; Boulyga, Sergei F.; Prohaska, Thomas

2012-01-01

We present the application of nanosecond laser ablation (LA) coupled to a ‘Nu Plasma HR’ multi collector inductively coupled plasma mass spectrometer (MC-ICP-MS) for the direct analysis of U isotope ratios in single, 10–20 μm-sized, U-doped glass particles. Method development included studies with respect to (1) external correction of the measured U isotope ratios in glass particles, (2) the applied laser ablation carrier gas (i.e. Ar versus He) and (3) the accurate determination of lower abundant 236U/238U isotope ratios (i.e. 10−5). In addition, a data processing procedure was developed for evaluation of transient signals, which is of potential use for routine application of the developed method. We demonstrate that the developed method is reliable and well suited for determining U isotope ratios of individual particles. Analyses of twenty-eight S1 glass particles, measured under optimized conditions, yielded average biases of less than 0.6% from the certified values for 234U/238U and 235U/238U ratios. Experimental results obtained for 236U/238U isotope ratios deviated by less than −2.5% from the certified values. Expanded relative total combined standard uncertainties Uc (k = 2) of 2.6%, 1.4% and 5.8% were calculated for 234U/238U, 235U/238U and 236U/238U, respectively. PMID:22595724

Direct uranium isotope ratio analysis of single micrometer-sized glass particles.

PubMed

Kappel, Stefanie; Boulyga, Sergei F; Prohaska, Thomas

2012-11-01

We present the application of nanosecond laser ablation (LA) coupled to a 'Nu Plasma HR' multi collector inductively coupled plasma mass spectrometer (MC-ICP-MS) for the direct analysis of U isotope ratios in single, 10-20 μm-sized, U-doped glass particles. Method development included studies with respect to (1) external correction of the measured U isotope ratios in glass particles, (2) the applied laser ablation carrier gas (i.e. Ar versus He) and (3) the accurate determination of lower abundant (236)U/(238)U isotope ratios (i.e. 10(-5)). In addition, a data processing procedure was developed for evaluation of transient signals, which is of potential use for routine application of the developed method. We demonstrate that the developed method is reliable and well suited for determining U isotope ratios of individual particles. Analyses of twenty-eight S1 glass particles, measured under optimized conditions, yielded average biases of less than 0.6% from the certified values for (234)U/(238)U and (235)U/(238)U ratios. Experimental results obtained for (236)U/(238)U isotope ratios deviated by less than -2.5% from the certified values. Expanded relative total combined standard uncertainties U(c) (k = 2) of 2.6%, 1.4% and 5.8% were calculated for (234)U/(238)U, (235)U/(238)U and (236)U/(238)U, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Identifying Hydrological Controls in the Lower Nelson River Basin utilizing Stable Water Isotopes

NASA Astrophysics Data System (ADS)

Delavau, C. J.; Smith, A. A.; Stadnyk, T.; Koenig, K.

2012-12-01

In 2010 a Stable Water Isotope (SWI) Monitoring Network was established within the lower Nelson River Basin (LNRB) (approximately 90,000 km2) in northern Manitoba, Canada, through a joint collaboration between the University of Manitoba and Manitoba Hydro (MH). The monitoring network encompasses over 60 sites where surface waters are regularly sampled, four sites sampling isotopes in precipitation, two sites utilizing drive point piezometers for the isotopic sampling of baseflow waters, and one site collecting evaporatively enriched water samples from an evaporation pan. In addition, two synoptic surveys have been completed in June 2011 and July 2012 to obtain annual snapshots of the monitoring network at a point in time. Currently, over 700 samples have been collected and analyzed. The LNRB contains approximately 9% of the total Nelson River Basin (NRB) drainage area, which encompasses an area of over 1 million km2. A diversion from the Churchill River through the Rat/Burntwood system routes an additional portion of flow into the northwest portion of the LNRB. The LNRB is significant to MH's network as it represents 75% of their power generation potential through six generating stations, thus resulting in a large portion of the basin being regulated. The watershed is topographically flat, therefore the movement and runoff of water, as well as isotopic composition of streamflow, is suspected to be highly impacted by changes in landscape and hydrography. The LNRB is a coniferous and wetland dominated basin, with almost 35% of the land cover composed of coniferous forest and 40% comprised of wetlands and lakes. Interpretation of the LNRB isotope framework shows that the major water sources (rainfall, snowfall, groundwater and surface waters) and rivers are isotopically distinct from one another. The main stem of the Nelson River shows little spatial or temporal variability, with an average δ18O of -10.6‰ and a standard deviation of 0.5‰ throughout the sampling

The Nation's Report Card Reading 2009 Trial Urban District Snapshot Report. San Diego Unified School District. Grade 8, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each district that participated in the National Assessment of Educational Progress (NAEP) 2009 Trial Urban District Assessment in reading receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for San Diego Unified School District's student achievement in reading. In 2009,…

The Nation's Report Card Reading 2009 Trial Urban District Snapshot Report. San Diego Unified School District. Grade 4, Public Schools

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

Each district that participated in the National Assessment of Educational Progress (NAEP) 2009 Trial Urban District Assessment in reading receives a one-page snapshot report that presents key findings and trends in a condensed format. This report presents the results for San Diego Unified School District's student achievement in reading. In 2009,…

Integrated modelling of enhanced in situ biodenitrification in a fractured aquifer: biogeochemistry and isotope geochemistry

NASA Astrophysics Data System (ADS)

Rodríguez-Escales, Paula; Folch, Albert; van Breukelen, Boris M.; Vidal-Gavilan, Georgina; Soler, Albert

2014-05-01

Enhanced in-situ biodenitrification is a feasible technology to recovery groundwater polluted by nitrates and achieves drinking water standards. Under optimum conditions, nitrate is reduced by autochthonous bacteria trough different reactions until arrive to harmless dinitrogen gas. Isotopic fractionation monitoring in field applications allows knowing the exact degree and the real scope of this technology. Using the Rayleigh equation the change in the isotope ratio of the nitrate molecule (δ15N-NO3-, δ18O-NO3-) is related to the fraction of molecules remaining as a result of biodenitrification. However, Rayleigh application at field scale is sometimes limited due to other processes involved during groundwater flow such as dispersion or adsorption and geological media heterogeneities that interferes in concentration values. Then, include isotope fractionation processes in reactive transport models is a useful tool to interpret and predict data from in-situ biodenitrification. We developed a reactive transport model of enhanced in situ application at field scale in a fractured aquifer that considers biogeochemical processes as well as isotope fractionation to enable better monitoring and management of this technology. Processes considered were: microbiological- exogenous and endogenous nitrate and sulfate respiration coupled with microbial growth and decay, geochemical reactions (precipitation of calcite) and isotopic fractionation (δ15N-NO3-; δ18O- NO3- and carbon isotope network). The 2-D simulations at field scale were developed using PHAST code. Modeling of nitrate isotope geochemistry has allowed determining the extent of biodenitrification in model domain. We have quantified which is the importance in decreasing of nitrate concentrations due to biodegradation (percentage of biodegradation, 'B%') and due to dilution process (percentage of dilution, 'D%'). On the other hand, the stable carbon isotope geochemistry has been modeled. We have considered the

Mono-isotope Prediction for Mass Spectra Using Bayes Network.

PubMed

Li, Hui; Liu, Chunmei; Rwebangira, Mugizi Robert; Burge, Legand

2014-12-01

Mass spectrometry is one of the widely utilized important methods to study protein functions and components. The challenge of mono-isotope pattern recognition from large scale protein mass spectral data needs computational algorithms and tools to speed up the analysis and improve the analytic results. We utilized naïve Bayes network as the classifier with the assumption that the selected features are independent to predict mono-isotope pattern from mass spectrometry. Mono-isotopes detected from validated theoretical spectra were used as prior information in the Bayes method. Three main features extracted from the dataset were employed as independent variables in our model. The application of the proposed algorithm to publicMo dataset demonstrates that our naïve Bayes classifier is advantageous over existing methods in both accuracy and sensitivity.

Image segmentation for uranium isotopic analysis by SIMS: Combined adaptive thresholding and marker controlled watershed approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Willingham, David G.; Naes, Benjamin E.; Heasler, Patrick G.

A novel approach to particle identification and particle isotope ratio determination has been developed for nuclear safeguard applications. This particle search approach combines an adaptive thresholding algorithm and marker-controlled watershed segmentation (MCWS) transform, which improves the secondary ion mass spectrometry (SIMS) isotopic analysis of uranium containing particle populations for nuclear safeguards applications. The Niblack assisted MCWS approach (a.k.a. SEEKER) developed for this work has improved the identification of isotopically unique uranium particles under conditions that have historically presented significant challenges for SIMS image data processing techniques. Particles obtained from five NIST uranium certified reference materials (CRM U129A, U015, U150, U500more » and U850) were successfully identified in regions of SIMS image data 1) where a high variability in image intensity existed, 2) where particles were touching or were in close proximity to one another and/or 3) where the magnitude of ion signal for a given region was count limited. Analysis of the isotopic distributions of uranium containing particles identified by SEEKER showed four distinct, accurately identified 235U enrichment distributions, corresponding to the NIST certified 235U/238U isotope ratios for CRM U129A/U015 (not statistically differentiated), U150, U500 and U850. Additionally, comparison of the minor uranium isotope (234U, 235U and 236U) atom percent values verified that, even in the absence of high precision isotope ratio measurements, SEEKER could be used to segment isotopically unique uranium particles from SIMS image data. Although demonstrated specifically for SIMS analysis of uranium containing particles for nuclear safeguards, SEEKER has application in addressing a broad set of image processing challenges.« less

Extending the Boundaries of Isotope Ratio MS - Latest Technological Improvements

NASA Astrophysics Data System (ADS)

Hilkert, A.

2016-12-01

Isotope ratio mass spectrometry has a long history, which started with the analysis of the isotopes of CO2. Over several decades a broad range of IRMS techniques has been derived like multi-collector high resolution ICP-MS, TIMS, noble gas static MS and gas IRMS. These different flavors of IRMS are now building a technology tool box, which allows to derive new applications build on new capabilities by combination of specific features of these sister technologies. In the 90's inductive coupled plasma ionization was added for the high precision analysis of rare elements. In 2000 extended multicollection opened the way into clumped isotopes. In 2008 the concept of a high resolution gas source IRMS was layed out to revolutionize stable gas IRMS recently followed by the combination of this static multicollection mode with fast mass scans of the single collector double focusing high resolution GCMS. Recently new technologies were created, like the mid infrared analyzers (IRIS) based on difference frequency generation lasers, the combination of a collision cell with HR MC ICPMS as well as the use of a high resolution electrostatic ion trap for extended stable isotope analysis on individual compounds. All these building blocks for IRMS address selected requirements of sample preparation, sample introduction, referencing, ionization, mass separation, ion detection or signal amplification. Along these lines new technological improvements and applications will be shown and discussed.

Development of laser ablation multi-collector inductively coupled plasma mass spectrometry for boron isotopic measurement in marine biocarbonates: new improvements and application to a modern Porites coral.

PubMed

Thil, François; Blamart, Dominique; Assailly, Caroline; Lazareth, Claire E; Leblanc, Thierry; Butsher, John; Douville, Eric

2016-02-15

Laser Ablation coupled to Multi-Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICPMS) is a powerful tool for the high-precision measurement of the isotopic ratios of many elements in geological samples, with the isotope ratio ((11) B/(10) B) of boron being used as an indicator of the pH of oceanic waters. Most geological samples or standards are polished and ablation occurs on flat surfaces. However, the shape and the irregularities of marine biocarbonates (e.g., corals, foraminifera) can make precise isotopic measurements of boron difficult. Even after polishing, the porosity properties and the presence of holes or micro-fractures affect the signal and the isotopic ratio when ablating the material, especially in raster mode. The effect of porosity and of the crater itself on the (11) B signal and the isotopic ratio acquired by LA-MC-ICPMS in both raster and spot mode was studied. Characterization of the craters was then performed with an optical profilometer to determine their shapes and depths. Surface state effects were examined by analyzing the isotopic fractionation of boron in silicate (NIST-SRM 612 and 610 standards) and in carbonate (corals). Surface irregularities led to a considerable loss of signal when the crater depth exceeded 20 µm. The stability and precision were degraded when ablation occurred in a deep cavity. The effect of laser focusing and of blank correction was also highlighted and our observations indicate that the accuracy of the boron isotopic ratio does not depend on the shape of the surface. After validation of the analytical protocol for boron isotopes, a raster application on a Porites coral, which grew for 18 months in an aquarium after field sampling, was carried out. This original LA-MC-ICPMS study revealed a well-marked boron isotope ratio temporal variability, probably related to growth rate and density changes, irrespective of the pH of the surrounding seawater. Copyright © 2015 John Wiley & Sons, Ltd. Copyright

New Applications of Cosmogenic Radioactive Isotopes to Study Water Travel Times

NASA Astrophysics Data System (ADS)

Visser, A.; Thaw, M.; Deinhart, A.; Bibby, R. K.; Esser, B.

2017-12-01

The travel time of water moving through a landscape influences nutrient dynamics and biogeochemical cycles. Constraining water travel times helps to understand the functioning of the critical zone. Water travel times cannot be observed directly but can be constrained by measurements of cosmogenic radioactive isotopes. We studied a small (4.6 km2) subalpine (1660-2117 m) catchment in a Mediterranean climate (8 °C, 1200 mm/yr) in the California Sierra Nevada to assess subsurface water storage dynamics and investigate flow paths and flow velocities. We analyzed a combination of three cosmogenic radioactive isotopes with half-lives varying from 87 days (sulfur-35), 2.6 years (sodium-22) to 12.3 years (tritium) in precipitation and stream samples. Water stable isotopes and solute chemistry aided the interpretation of the cosmogenic isotopes. Tritium samples (1L) are analyzed by noble gas mass spectrometry after helium-3 accumulation. Samples for sulfur-35 and sodium-22 are collected by processing 20-1000 L of water through an anion and cation exchange column in-situ. Sulfur-35 is analyzed by liquid scintillation counting after chemical purification and precipitation. Sodium-22 is analyzed by gamma counting after eluting the cations into a 4L Marinelli beaker. Monthly collected precipitation samples show variability of deposition rate for tritium and sulfur-35. Sodium-22 levels in cumulative yearly precipitation samples are consistent with recent studies in the US and Japan. The observed variability of deposition rates complicates direct use as decaying age tracers. The level and variability of tritium in monthly stream samples indicate a mean residence time on the order of 10 years and only small contributions of younger water during high flow conditions. Sulfur-35 and sodium-22 concentrations were critically interpreted considering possible uptake by vegetation and cation exchange. Detections of sodium-22 confirm a small fraction of younger (< 5 years) water. Low

Nanohole-array-based device for 2D snapshot multispectral imaging

PubMed Central

Najiminaini, Mohamadreza; Vasefi, Fartash; Kaminska, Bozena; Carson, Jeffrey J. L.

2013-01-01

We present a two-dimensional (2D) snapshot multispectral imager that utilizes the optical transmission characteristics of nanohole arrays (NHAs) in a gold film to resolve a mixture of input colors into multiple spectral bands. The multispectral device consists of blocks of NHAs, wherein each NHA has a unique periodicity that results in transmission resonances and minima in the visible and near-infrared regions. The multispectral device was illuminated over a wide spectral range, and the transmission was spectrally unmixed using a least-squares estimation algorithm. A NHA-based multispectral imaging system was built and tested in both reflection and transmission modes. The NHA-based multispectral imager was capable of extracting 2D multispectral images representative of four independent bands within the spectral range of 662 nm to 832 nm for a variety of targets. The multispectral device can potentially be integrated into a variety of imaging sensor systems. PMID:24005065

Oxygen Isotopes Archived in Subfossil Chironomids: Advancing a Promising Proxy for Lake Water Isotopes

NASA Astrophysics Data System (ADS)

Lasher, G. E.; Axford, Y.; Blair, N. E.

2017-12-01

Oxygen isotopes measured in subfossil chironomid head capsules (aquatic insect remains) in lake sediments are beginning to offer paleoclimate insights from previously under-studied areas of the world. Since the first published pilot study demonstrated the potential of chironomid δ18O to record lake water δ18O (Wooller et al., 2004), subsequent work has refined our understanding of this proxy: confirming via lab cultures that growth water controls head capsule δ18O (Wang et al., 2009), refining laboratory pretreatment protocols, and further validating the method by demonstrating strong agreement between carbonate and chironomid-derived paleo-isotope records (Verbruggen et al., 2009, 2010, 2011). However, outstanding questions remain, including the seasonality of chironomid growth, possible species-dependent vital effects, and diagenetic effects on the protein-chitin complex that comprise chironomid cuticles. To address some of these questions, we summarize available data from paired modern chironomid-lake water δ18O values from around the world and discuss climatic and environmental factors affecting chironomid isotopic signatures. We also present new data on the resistance of these subfossils to diagenesis and degradation throughout the late Quaternary using Fourier Transform Infrared Spectroscopy (FT-IR) and Pyrolysis Gas Chromatography Mass Spectrometry (Py-GC/MS) of chironomid remains up to >100,000 years old. As chironomids are nearly ubiquitous in lakes globally and, we argue, molecularly stable through glacial and interglacial cycles, this proxy has the potential to greatly expand the spatial and temporal resolution of Quaternary paleo-isotopes and thus climate records. In addition to reviewing and presenting new methodological advances, we also present applications of chironomid δ18O from millennial- to centennial-scale Holocene Greenland lake records.

Strontium isotopic signatures of oil-field waters: Applications for reservoir characterization

USGS Publications Warehouse

Barnaby, R.J.; Oetting, G.C.; Gao, G.

2004-01-01

The 87Sr/86Sr compositions of formation waters that were collected from 71 wells producing from a Pennsylvanian carbonate reservoir in New Mexico display a well-defined distribution, with radiogenic waters (up to 0.710129) at the updip western part of the reservoir, grading downdip to less radiogenic waters (as low as 0.708903 to the east. Salinity (2800-50,000 mg/L) displays a parallel trend; saline waters to the west pass downdip to brackish waters. Elemental and isotopic data indicate that the waters originated as meteoric precipitation and acquired their salinity and radiogenic 87Sr through dissolution of Upper Permian evaporites. These meteoric-derived waters descended, perhaps along deeply penetrating faults, driven by gravity and density, to depths of more than 7000 ft (2100 m). The 87 Sr/86Sr and salinity trends record influx of these waters along the western field margin and downdip flow across the field, consistent with the strong water drive, potentiometric gradient, and tilted gas-oil-water contacts. The formation water 87Sr/86Sr composition can be useful to evaluate subsurface flow and reservoir behavior, especially in immature fields with scarce pressure and production data. In mature reservoirs, Sr Sr isotopes can be used to differentiate original formation water from injected water for waterflood surveillance. Strontium isotopes thus provide a valuable tool for both static and dynamic reservoir characterization in conjunction with conventional studies using seismic, log, core, engineering, and production data. Copyright ??2004. The American Association of Petroleum Geologist. All rights reserved.

Calcium and Oxygen Isotopic Composition of Calcium Carbonates

NASA Astrophysics Data System (ADS)

Niedermayr, Andrea; Eisenhauer, Anton; Böhm, Florian; Kisakürek, Basak; Balzer, Isabelle; Immenhauser, Adrian; Jürgen Köhler, Stephan; Dietzel, Martin

2016-04-01

Ca. On the other hand, 40Ca may desorb more easily, especially if the bond strength is lower as in the case of aragonite. For kinetic oxygen isotopic fractionation, the faster deprotonation of HC16O3- and the faster incorporation of C16O32- at the surfaces causes a smaller enrichment of 18O in all three polymorphs, which will be preserved at higher precipitation rates. In consequence to the different behavior of calcium and oxygen isotopes, they can be useful for multiproxy applications. Thereby calcium isotopes can be used to identify kinetic effects, especially if both aragonite and calcite, can be analyzed in one sample. Oxygen isotopes are more strongly related to temperature. [1]A. Niedermayr, S.J. Köhler and M. Dietzel (2013), Chemical Geology, 340, 105-120.

A stable isotope-based approach to tropical dendroclimatology

NASA Astrophysics Data System (ADS)

Evans, Michael N.; Schrag, Daniel P.

2004-08-01

We describe a strategy for development of chronological control in tropical trees lacking demonstrably annual ring formation, using high resolution δ 18O measurements in tropical wood. The approach applies existing models of the oxygen isotopic composition of alpha-cellulose (Roden et al., 2000), a rapid method for cellulose extraction from raw wood (Brendel et al., 2000), and continuous flow isotope ratio mass spectrometry (Brenna et al., 1998) to develop proxy chronological, rainfall and growth rate estimates from tropical trees lacking visible annual ring structure. Consistent with model predictions, pilot datasets from the temperate US and Costa Rica having independent chronological control suggest that observed cyclic isotopic signatures of several permil (SMOW) represent the annual cycle of local rainfall and relative humidity. Additional data from a plantation tree of known age from ENSO-sensitive northwestern coastal Peru suggests that the 1997-8 ENSO warm phase event was recorded as an 8‰ anomaly in the δ 18O of α-cellulose. The results demonstrate reproducibility of the stable isotopic chronometer over decades, two different climatic zones, and three tropical tree genera, and point to future applications in paleoclimatology.

Stable isotope methodology in the pharmacokinetic studies of androgenic steroids in humans.

PubMed

Shinohara, Y; Baba, S

1990-04-01

The use of stable isotopically labeled steroids combined with gas chromatography/mass spectrometry (GC/MS) has found a broad application in pharmacologic studies. Initially, stable isotopically labeled steroids served as the ideal analytic internal standard for GC/MS analysis; however, their in vivo use has expanded and has proven to be a powerful pharmacokinetic tool. We have successfully used stable isotope methodology to study the pharmacokinetic/bioavailability of androgens. The primary advantage of the technique is that endogenous and exogenous steroids with the same basic structure can be differentiated by using stable isotopically labeled analogs. The method was used to examine the pharmacokinetics of testosterone and testosterone propionate, and to clarify the influence of endogenous testosterone. Another advantage of the isotope methods is that steroidal drugs can be administered concomitantly in two formulations (e.g., solution and solid dosage). A single set of blood samples serves to describe the time course of the formulations being compared. This stable isotope coadministration technique was used to estimate the relative bioavailability of 17 alpha-methyltestosterone.

Synthetic isotope mixtures for the calibration of isotope amount ratio measurements of carbon

NASA Astrophysics Data System (ADS)

Russe, K.; Valkiers, S.; Taylor, P. D. P.

2004-07-01

Synthetic isotope mixtures for the calibration of carbon isotope amount ratio measurements have been prepared by mixing carbon tetrafluoride highly enriched in 13C with carbon tetrafluoride depleted in 13C. Mixing procedures based on volumetry and gravimetry are described. The mixtures served as primary measurement standards for the calibration of isotope amount ratio measurements of the Isotopic Reference Materials PEF1, NBS22 and USGS24. Thus SI-traceable measurements of absolute carbon isotope amount ratios have been performed for the first time without any hypothesis needed for a correction of oxygen isotope abundances, such as is the case for measurements on carbon dioxide. As a result, "absolute" carbon isotope amount ratios determined via carbon tetrafluoride have smaller uncertainties than those published for carbon dioxide. From the measurements of the Reference Materials concerned, the absolute carbon isotope amount ratio of Vienna Pee Dee Belemnite (VPDB)--the hypothetical material upon which the scale for relative carbon isotope ratio measurements is based--was calculated to be R13(VPDB) = (11 101 +/- 16) × 10-6.

Method for separating isotopes

DOEpatents

Jepson, B.E.

1975-10-21

Isotopes are separated by contacting a feed solution containing the isotopes with a cyclic polyether wherein a complex of one isotope is formed with the cyclic polyether, the cyclic polyether complex is extracted from the feed solution, and the isotope is thereafter separated from the cyclic polyether.

Preliminary results of oxygen isotope ratio measurement with a particle-gamma coincidence method

NASA Astrophysics Data System (ADS)

Borysiuk, Maciek; Kristiansson, Per; Ros, Linus; Abdel, Nassem S.; Elfman, Mikael; Nilsson, Charlotta; Pallon, Jan

2015-04-01

The possibility to study variations in the oxygen isotopic ratio with photon tagged nuclear reaction analysis (pNRA) is evaluated in the current work. The experiment described in the article was performed at Lund Ion Beam Analysis Facility (LIBAF) with a 2 MeV deuteron beam. Isotopic fractionation of light elements such as carbon, oxygen and nitrogen is the basis of many analytical tools in hydrology, geology, paleobiology and paleogeology. IBA methods provide one possible tool for measurement of isotopic content. During this experimental run we focused on measurement of the oxygen isotopic ratio. The measurement of stable isotopes of oxygen has a number of applications; the particular one driving the current investigation belongs to the field of astrogeology and specifically evaluation of fossil extraterrestrial material. There are three stable isotopes of oxygen: 16O, 17O and 18O. We procured samples highly enriched with all three isotopes. Isotopes 16O and 18O were easily detected in the enriched samples, but no significant signal from 17O was detected in the same samples. The measured yield was too low to detect 18O in a sample with natural abundances of oxygen isotopes, at least in the current experimental setup, but the spectral line from the reaction with 16O was clearly visible.

A Chandra Snapshot Survey of Extremely Red Quasars from SDSS BOSS and WISE

NASA Astrophysics Data System (ADS)

Garmire, Gordon

2017-09-01

We propose Chandra snapshot observations of a sample of 15 extremely red and highly luminous quasars at z > 2. These Type 1 objects have recently been discovered via the SDSS BOSS and WISE surveys, and they are among the most-luminous quasars in the Universe. They appear to be part of the missing evolutionary link as merger-induced starburst galaxies transform into typical ultraviolet luminous quasars. Our aim is to efficiently gather X-ray information about a sufficiently large sample of these objects that general conclusions about their basic X-ray properties, especially obscuration level and luminosity, can be drawn reliably. The results will also allow effective targeting of promising objects in longer X-ray spectroscopic observations.

Planetary Accretion, Oxygen Isotopes and the Central Limit Theorem

NASA Technical Reports Server (NTRS)

Nuth, Joseph A., III; Hill, Hugh G. M.; Vondrak, Richard R. (Technical Monitor)

2001-01-01

The accumulation of presolar dust into increasingly larger aggregates (CAIs and Chondrules, Asteroids, Planets) should result in a very drastic reduction in the numerical spread in oxygen isotopic composition between bodies of similar size, in accord with the Central Limit Theorem. Observed variations in oxygen isotopic composition are many orders of magnitude larger than would be predicted by a simple, random accumulation model that begins in a well-mixed nebula - no matter which size-scale objects are used as the beginning or end points of the calculation. This discrepancy implies either that some as yet unspecified process acted on the solids in the Solar Nebula to increase the spread in oxygen isotopic composition during each and every stage of accumulation or that the nebula was heterogeneous and maintained this heterogeneity throughout most of nebular history. Large-scale nebular heterogeneity would have significant consequences for many areas of cosmochemistry, including the application of some well-known isotopic systems to the dating of nebular events or the prediction of bulk compositions of planetary bodies on the basis of a uniform cosmic abundance.

Advances in Methane Isotope Measurements via Direct Absorption Spectroscopy with Applications to Oil and Gas Source Characterization

NASA Astrophysics Data System (ADS)

Yacovitch, T. I.; Herndon, S. C.; Roscioli, J. R.; Petron, G.; Shorter, J. H.; Jervis, D.; McManus, J. B.; Nelson, D. D.; Zahniser, M. S.; Kolb, C. E., Jr.

2015-12-01

Instrumental developments in the measurement of multiple isotopes of methane (12CH4, 13CH4 and 12CH3D) are presented. A first generation 8-micron instrument quantifies 12CH4 and 13CH4 at a 1-second rate via tunable infrared direct absorption spectroscopy (TILDAS). A second generation instrument uses two 3-micron intraband cascade lasers in an Aerodyne dual laser chassis for simultaneous measurement of 12CH4, 13CH4 and 12CH3D. Sensitivity and noise performance improvements are examined. The isotopic signature of methane provides valuable information for emission source identification of this greenhouse gas. A first generation spectrometer has been deployed in the field on a mobile laboratory along with a sophisticated 4-tank calibration system. Calibrations are done on an agressive schedule, allowing for the correction of measured isotope ratios to an absolute isotope scale. Distinct isotopic signatures are found for a number of emission sources in the Denver-Julesburg Basin: oil and gas gathering stations, compressor stations and processing plants; a municipal landfill, and dairy/cattle operations. The isotopic signatures are compared with measured ethane/methane ratios. These direct absorption measurements have larger uncertainties than samples measured via gas chromatography-mass spectrometry, but have several advantages over canister sampling methods: individual sources of short duration are easier to isolate; calibrated isotope ratio results are available immediately; replicate measurements on a single source are easily performed; and the number of sources sampled is not limited by canister availability and processing time.

The Austrian Network of Isotopes in Precipitation and Surface water: more than 50 years applications and interpretations of basic isotope-hydrological data for Central Europe

NASA Astrophysics Data System (ADS)

Wyhlidal, S.; Rank, D.; Kralik, M.

2017-12-01

Austria runs one of the longest-standing and most dense isotope precipitation collection networks worldwide, resulting in a unique isotope time series. Stable isotope variations in precipitation are a consequence of isotope effects accompanying each step of the water cycle. Therefore, stable isotope ratios of oxygen (18O/16O) and hydrogen (2H/1H) in precipitation provide important information about the origin and atmospheric transport of water vapour. The separation of a remote moisture source signals from local influences is thereby challenging. The amount of precipitation in Austria is highly influenced by the Alpine mountain range (400-3.000 mm/a). The amount of annual precipitation increases towards the mountain ranges. However, strong regional differences exist between the north and south of the Austrian Alps because the Alpine range functions as weather divide. The isotope time series of the stations of the Austrian precipitation network show significant but not uniform long-term trends. While the 10-year running mean of some mountain stations exhibit a highly significant increase in δ18O of about 1 ‰ since 1975, the change of δ18O at the valley stations is less pronounced. The increasing δ18O values can be correlated to an increase mean air temperature in the Alpine area and can be used as an additional indicator of climate change in this region. The differences in δ18O-values of sampling stations at similar altitudes can be explained by the origin of the air moisture. An Atlantic influence causes lower δ18O-values than sources from the Mediterranean. This can be explained by the different distances to the sea. Deuterium excess is a second-order isotopic parameter which is often interpreted as a tracer of the evaporation conditions of water vapor at the moisture source in terms of relative humidity, wind speed, and sea surface temperature, but can also be modified by local influences, such as below-cloud evaporation and equilibrium fractionation under

Evaluated nuclear data files for the naturally-occurring isotopes of cadmium

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCabe, J.; Smith, A.B.; Meadows, J.W.

1993-06-01

Comprehensive neutronic evaluated data files for the naturally-occurring isotopes of cadmium are deduced from experimental data and nuclear models, and presented in the ENDF/B-VI formats. Particular attention is given to those processes relevant to fuel-cycle and fission-product applications. Comparisons are made with prior evaluations of the cadmium isotopes, and discrepancies and consistencies cited. Some of the discrepancies are very large 9.9 as much as 100%), and the differences have the potential for a pronounced impact on applications usage. The present files are comprehensive, including may important processes that are not represented in the contemporary ENDF/B-VI system. Recommendations are made formore » future measurements where appropriate.« less

Isotope effects in the evaporation of water: a status report of the Craig-Gordon model.

PubMed

Horita, Juske; Rozanski, Kazimierz; Cohen, Shabtai

2008-03-01

The Craig-Gordon model (C-G model) [H. Craig, L.I. Gordon. Deuterium and oxygen 18 variations in the ocean and the marine atmosphere. In Stable Isotopes in Oceanographic Studies and Paleotemperatures, E. Tongiorgi (Ed.), pp. 9-130, Laboratorio di Geologia Nucleare, Pisa (1965).] has been synonymous with the isotope effects associated with the evaporation of water from surface waters, soils, and vegetations, which in turn constitutes a critical component of the global water cycle. On the occasion of the four decades of its successful applications to isotope geochemistry and hydrology, an attempt is made to: (a) examine its physical background within the framework of modern evaporation models, (b) evaluate our current knowledge of the environmental parameters of the C-G model, and (c) comment on a general strategy for the use of these parameters in field applications. Despite its simplistic representation of evaporation processes at the water-air interface, the C-G model appears to be adequate to provide the isotopic composition of the evaporation flux. This is largely due to its nature for representing isotopic compositions (a ratio of two fluxes of different isotopic water molecules) under the same environmental conditions. Among many environmental parameters that are included in the C-G model, accurate description and calculations are still problematic of the kinetic isotope effects that occur in a diffusion-dominated thin layer of air next to the water-air interface. In field applications, it is of importance to accurately evaluate several environmental parameters, particularly the relative humidity and isotopic compositions of the 'free-atmosphere', for a system under investigation over a given time-scale of interest (e.g., hourly to daily to seasonally). With a growing interest in the studies of water cycles of different spatial and temporal scales, including paleoclimate and water resource studies, the importance and utility of the C-G model is also likely to

Refined Use of Satellite Aerosol Optical Depth Snapshots to Constrain Biomass Burning Emissions in the GOCART Model

NASA Astrophysics Data System (ADS)

Petrenko, Mariya; Kahn, Ralph; Chin, Mian; Limbacher, James

2017-10-01

Simulations of biomass burning (BB) emissions in global chemistry and aerosol transport models depend on external inventories, which provide location and strength for BB aerosol sources. Our previous work shows that to first order, satellite snapshots of aerosol optical depth (AOD) near the emitted smoke plume can be used to constrain model-simulated AOD, and effectively, the smoke source strength. We now refine the satellite-snapshot method and investigate where applying simple multiplicative emission adjustment factors alone to the widely used Global Fire Emission Database version 3 emission inventory can achieve regional-scale consistency between Moderate Resolution Imaging Spectroradiometer (MODIS) AOD snapshots and the Goddard Chemistry Aerosol Radiation and Transport model. The model and satellite AOD are compared globally, over a set of BB cases observed by the MODIS instrument during the 2004, and 2006-2008 biomass burning seasons. Regional discrepancies between the model and satellite are diverse around the globe yet quite consistent within most ecosystems. We refine our approach to address physically based limitations of our earlier work (1) by expanding the number of fire cases from 124 to almost 900, (2) by using scaled reanalysis-model simulations to fill missing AOD retrievals in the MODIS observations, (3) by distinguishing the BB components of the total aerosol load from background aerosol in the near-source regions, and (4) by including emissions from fires too small to be identified explicitly in the satellite observations. The small-fire emission adjustment shows the complimentary nature of correcting for source strength and adding geographically distinct missing sources. Our analysis indicates that the method works best for fire cases where the BB fraction of total AOD is high, primarily evergreen or deciduous forests. In heavily polluted or agricultural burning regions, where smoke and background AOD values tend to be comparable, this approach

Assessing the applicability of stable isotope analysis to determine the contribution of landfills to vultures' diet.

PubMed

Tauler-Ametller, Helena; Hernández-Matías, Antonio; Parés, Francesc; Pretus, Joan Ll; Real, Joan

2018-01-01

Human activities cause changes to occur in the environment that affect resource availability for wildlife. The increase in the human population of cities has led to a rise in the amount of waste deposited in landfills, installations that have become a new food resource for both pest and threatened species such as vultures. In this study we used stable isotope analysis (SIA) and conventional identification of food remains from Egyptian Vultures (Neophron percnopterus) to assess the applicability of SIA as a new tool for determining the composition of the diets of vultures, a group of avian scavengers that is threatened worldwide. We focused on an expanding Egyptian Vulture population in NE Iberian Peninsula to determine the part played by landfills and livestock in the diet of these species, and aimed to reduce the biases associated with conventional ways of identifying food remains. We compared proportions of diet composition obtained with isotope mixing models and conventional analysis for five main prey. The greatest agreement between the two methods was in the categories 'landfills' and 'birds' and the greatest differences between the results from the two methods were in the categories 'livestock', 'carnivores' and 'wild herbivores'. Despite uncertainty associated to SIA, our results showed that stable isotope analysis can help to distinguish between animals that rely on waste and so present enriched levels of δ 13C than those that feed on the countryside. Indeed, a high proportion of food derived from landfills (nearly 50%) was detected in some breeding pairs. Furthermore we performed GLMM analyses that showed that high values of δ 13C in Egyptian Vulture feathers (a proxy of feeding in landfills) are related with high levels of humanization of territories. This method has the potential to be applied to other threatened vulture species for which there is a lack of information regarding resources they are consuming, being especially important as the main

Isotope reference materials

USGS Publications Warehouse

Coplen, Tyler B.

2010-01-01

Measurement of the same isotopically homogeneous sample by any laboratory worldwide should yield the same isotopic composition within analytical uncertainty. International distribution of light element isotopic reference materials by the International Atomic Energy Agency and the U.S. National Institute of Standards and Technology enable laboratories to achieve this goal.

Stable carbon and nitrogen isotope composition of aquatic and terrestrial plants of the San Francisco Bay estuarine system

USGS Publications Warehouse

Cloern, J.E.; Canuel, E.A.; Harris, D.

2002-01-01

We report measurements of seasonal variability in the C-N stable isotope ratios of plants collected across the habitat mosaic of San Francisco Bay, its marshes, and its tributary river system. Analyses of 868 plant samples were binned into 10 groups (e.g., terrestrial riparian, freshwater phytoplankton, salt marsh) to determine whether C-N isotopes can be used as biomarkers for tracing the origins of organic matter in this river-marsh-estuary complex. Variability of ??13C and ??15N was high (???5-10???) within each plant group, and we identified three modes of variability: (1) between species and their microhabitats, (2) over annual cycles of plant growth and senescence, and (3) between living and decomposing biomass. These modes of within-group variability obscure any source-specific isotopic signatures, confounding the application of C-N isotopes for identifying the origins of organic matter. A second confounding factor was large dissimilarity between the ??13C-??15N of primary producers and the organic-matter pools in the seston and sediments. Both confounding factors impede the application of C-N isotopes to reveal the food supply to primary consumers in ecosystems supporting diverse autotrophs and where the isotopic composition of organic matter has been transformed and become distinct from that of its parent plant sources. Our results support the advice of others: variability of C-N stable isotopes within all organic-matter pools is high and must be considered in applications of these isotopes to trace trophic linkages from primary producers to primary consumers. Isotope-based approaches are perhaps most powerful when used to complement other tools, such as molecular biomarkers, bioassays, direct measures of production, and compilations of organic-matter budgets.

Investigation of sulphur isotope variation due to different processes applied during uranium ore concentrate production.

PubMed

Krajkó, Judit; Varga, Zsolt; Wallenius, Maria; Mayer, Klaus; Konings, Rudy

The applicability and limitations of sulphur isotope ratio as a nuclear forensic signature have been studied. The typically applied leaching methods in uranium mining processes were simulated for five uranium ore samples and the n ( 34 S)/ n ( 32 S) ratios were measured. The sulphur isotope ratio variation during uranium ore concentrate (UOC) production was also followed using two real-life sample sets obtained from industrial UOC production facilities. Once the major source of sulphur is revealed, its appropriate application for origin assessment can be established. Our results confirm the previous assumption that process reagents have a significant effect on the n ( 34 S)/ n ( 32 S) ratio, thus the sulphur isotope ratio is in most cases a process-related signature.

Review of combined isotopic and optical nanoscopy

PubMed Central

Richter, Katharina N.; Rizzoli, Silvio O.; Jähne, Sebastian; Vogts, Angela; Lovric, Jelena

2017-01-01

Abstract. Investigating the detailed substructure of the cell is beyond the ability of conventional optical microscopy. Electron microscopy, therefore, has been the only option for such studies for several decades. The recent implementation of several super-resolution optical microscopy techniques has rendered the investigation of cellular substructure easier and more efficient. Nevertheless, optical microscopy only provides an image of the present structure of the cell, without any information on its long-temporal changes. These can be investigated by combining super-resolution optics with a nonoptical imaging technique, nanoscale secondary ion mass spectrometry, which investigates the isotopic composition of the samples. The resulting technique, combined isotopic and optical nanoscopy, enables the investigation of both the structure and the “history” of the cellular elements. The age and the turnover of cellular organelles can be read by isotopic imaging, while the structure can be analyzed by optical (fluorescence) approaches. We present these technologies, and we discuss their implementation for the study of biological samples. We conclude that, albeit complex, this type of technology is reliable enough for mass application to cell biology. PMID:28466025

Metal Stable Isotope Tagging: Renaissance of Radioimmunoassay for Multiplex and Absolute Quantification of Biomolecules.