bluuebunny/crossref_metadata_2025 huggingface dataset:
A Science Lesson Plan Analysis Instrument for formative and summative program evaluation of a teacher education program
Authors: Jacobs Christina L. , Martin Sonya N. , Otieno Tracey C.
Published: April 2008

In evaluating the success of teacher development programs, valid and scalable measures of teaching practice are needed. We have developed and validated the Science Lesson Plan Analysis Instrument (SLPAI) for quantitative evaluation of teacher‐generated multiday lesson plans. This paper presents the SLPAI as a complement to surveys and classroom observation, and demonstrates its use in 2 pilot studies. The SLPAI was used formatively to measure the teaching practices of incoming program cohorts and tailor program instruction. It was also used to track changes in teaching practice and pedagogical knowledge of participants over time, providing summative evidence of program effectiveness. © 2008 Wiley Periodicals, Inc. Sci Ed 92:1096–1126, 2008
Firm systems thinking: unifying educational problem solving
Authors: Johnson Genevieve Marie
Published: April 2008

Theorists and practitioners have debated the nature of educational systems and the most appropriate conceptualization of educational problems. Although terminology is idiosyncratic, both hard and soft systems thinking (SST) are evident in educational discourse. However, given that the school system has precise required outcomes (i.e. student achievement) coupled with subjective interpretation of those requirements (i.e. definition of an educated person), defining educational thought as either a hard or soft seems inappropriate and counter‐productive. Based on the assumption that human activity includes equally consequential objective and subjective realities, firms systems thinking is proposed as a unifying paradigm of educational problem solving. Firm systems thinking (FST) begins with the assumption that elements in a system are interconnected and interdependent. FST is appropriately applied to systems that: (1) have objective elements that are subject to individual interpretation; (2) have both precise and imprecise requirements and specifications and (3) focus on both micro (i.e. specific situation) and macro (e.g. general situation) improvement. FST is proposed as the logical progression of problem solving strategies in educational systems. Copyright © 2008 John Wiley & Sons, Ltd.
The combination of methamphetamine and of the HIV protein, Tat, induces death of the human neuroblastoma cell line, SH‐SY5Y
Authors: Cai Ning Sheng , Cadet Jean Lud
Published: April 2008

Human immunodeficiency virus (HIV)‐infected methamphetamine (METH) abusers show greater neuropathological abnormalities than HIV‐negative METH abusers or HIV‐positive non‐METH users. Herein, we investigated the effects of METH and of the HIV protein, Tat, using the human neuroblastoma cell line, SHY5Y. METH and Tat alone caused no toxic effects. In contrast, the combination of METH and Tat caused significant increases in the percentage of dead cells observed after 48 h of exposure. These results suggest the possibility of using this model to elucidate cellular and molecular mechanisms involved in the potentiation of clinical effects observed in patient populations of HIV‐positive METH‐abusing patients. Synapse 62:551–552, 2008. © 2008 Wiley‐Liss, Inc.
Autoradiographic characterization of α2C‐adrenoceptors in the human striatum
Authors: Fagerholm Veronica , Rokka Johanna , Nyman Leena , Sallinen Jukka , Tiihonen Jari , Tupala Erkki , Haaparanta Merja , Hietala Jarmo
Published: April 2008

Indirect experimental evidence suggests that drugs acting on the α2C‐adrenoceptor could be useful in the treatment of neuropsychiatric disorders such as depression and schizophrenia. In rodent brain, the highest levels of α2C‐adrenoceptors are found in the striatum, with lower levels in cerebral cortex and hippocampus. In human brain, because of the poor subtype‐selectivity of the available α2‐adrenoceptor ligands, the localization of α2C‐adrenoceptors has remained unknown. Recently, a selective α2C‐adrenoceptor antagonist, JP‐1302, was characterized, and to assess the presence of α2C‐adrenoceptors in human brain, we performed competition binding in vitro receptor autoradiography with JP‐1302 and the α2‐adrenoceptor subtype nonselective antagonist [ethyl‐3H]RS79948‐197 on rat and human postmortem brain sections. In striatum of both species, JP‐1302 vs. [ethyl‐3H]RS79948‐197 competition binding was biphasic, identifying high‐ and low‐affinity binding sites, whereas in cortex and cerebellum, only low‐affinity binding sites were detected. The results indicate that a significant portion of the α2‐adrenoceptors in striatum is of the α2C subtype, whereas non‐α2C‐adreocneptors predominate in cortex and cerebellum. Because the α2C‐adrenoceptor subtype distribution pattern appears to be conserved between rodents and humans, results obtained from studies on the role of the α2C‐adrenoceptor in rodent models of neuropsychiatric disorders may be relevant also for human diseases. Synapse 62:508–515, 2008. © 2008 Wiley‐Liss, Inc.
A comparison of the knowledge of chronic pain and its management between final year physiotherapy and medical students
Authors: Ali Nada , Thomson D.I.
Published: April 2008

The scientific literature reveals a surprising lack of knowledge of chronic pain mechanisms and its management amongst health care professionals, including physicians and physiotherapists. There is little information directly related to a comparison between medical and physiotherapy students’ knowledge of chronic pain. This study aimed to determine and compare the level of knowledge of chronic pain and its management between final year medical (n=126) and physiotherapy students (n=62). A chronic pain questionnaire which included two sections on knowledge and one section on management was used to gather quantitative and qualitative data. Final year physiotherapy students were found to have statistically greater knowledge of chronic pain than final year medical students (p=0.01 and p=0.002). In contrast, medical students were found to have statistically significantly greater understanding of the management of patients with chronic pain (p=0.001). Male students from both groups scored significantly higher in the management section (p=0.008) as did older students (p=0.01). There was a lack of understanding, in varying degrees, of central sensitization, opioid addition, fear‐avoidance and a number of students from both cohorts appeared to bring a curative focus to the treatment of chronic pain. One way forward could be found in the interprofessional agenda. This will offer students from different disciplines opportunities to understand their different roles and enhance each others’ learning base so that a biopsychosocial framework of care can be implemented. In this way, physiotherapists could learn more about the drug management of chronic pain and medical students could explore more collaborative patient‐centred paradigms that address issues such as self‐efficacy, self‐management and patient empowerment. More focus needs to be paid to the education of the health professionals regarding their assumptions and understanding what ‘vulnerable’ means in a tissue in comparison to a person.
Maternal death due to postpartum hemorrhage after snakebite
Authors: D'Ambruoso Lucia , Byass Peter , Ouedraogo Moctar
Published: April 2008

Synopsis

A case of fatal postpartum hemorrhage demonstrates the need for the immediate referral of all pregnant women who incur a snakebite.
Bhagat Singh as ‘Satyagrahi’: The Limits to Non-violence in Late Colonial India
Authors: NAIR NEETI
Published: April 2008

Among anti-colonial nationalists, Bhagat Singh and M.K. Gandhi are seen to exemplify absolutely contrasting strategies of resistance. Bhagat Singh is regarded as a violent revolutionary whereas Gandhi is the embodiment of non-violence. This paper argues that Bhagat Singh and his comrades became national heroes not after their murder of a police inspector in Lahore or after throwing bombs in the Legislative Assembly in New Delhi but during their practice of hunger strikes and non-violent civil disobedience within the walls of Lahore's prisons in 1929–30. In fact there was plenty in common in the strategies of resistance employed by both Gandhi and Bhagat Singh. By labelling these revolutionaries ‘murderers’ and ‘terrorists’, the British sought to dismiss their non-violent demands for rights as ‘political prisoners’. The same labels were adopted by Gandhi and his followers. However, the quality of anti-colonial nationalism represented by Bhagat Singh was central to the resolution of many of the divisions that racked pre-partition Punjab.
The utopia and reality of sovereignty: social reality, normative IR and ‘Organized Hypocrisy’
Authors: KARP DAVID JASON
Published: April 2008

This article applies E. H. Carr’s analysis of utopia and reality, and a Searlean-constructivist analysis of rules and norms, to the concept of ‘sovereignty’ in general, and Stephen Krasner’s argument in Sovereignty: Organized Hypocrisy in particular. In doing this, the article charts a theoretical space that incorporates insights from classical realism, scientific realism, and philosophical (social) constructivism. To view ‘utopia’ and ‘reality’ as distinct yet equally important planes of International Relations (IR) inquiry, thereby treating ‘sovereignty’ as a single concept with descriptive and normative elements, highlights both the merits and the shortcomings of Krasner’s approach. Furthermore, this type of analysis suggests a fruitful way to continue a contemporary normative discussion about what sovereign entities ought to do.
Why do states bother to deceive? Managing trust at home and abroad
Authors: JACOBSEN JOHN KURT
Published: April 2008

Why do democratic states try to deceive their own citizens as to the foreign policies they practice, their motives, and their consequences? This question presupposes not only that states craft ‘stories’ to disguise activities abroad, but that they do so because they are constrained by an audience of non-elite actors. Theories derived from realpolitik, at best, make little allowance for such domestic ‘interference’. Yet there is evidence that in democracies the role of mass publics in driving, curbing, or modifying the conduct of foreign policy is a force, and explanatory factor, to reckon with.
‘Real’? As if! Critical reflections on state personhood
Authors: SCHIFF JACOB
Published: April 2008

In a 2004 forum, Alexander Wendt, Patrick Jackson, Colin Wight and Iver Neumann asked two questions about state personhood: Are states real, or merely as-if? Are they people? I question the terms of their debate, which relies upon a problematic distinction between ‘real’ and ‘as if’. Drawing largely upon Foucault, I challenge that distinction. This challenge has important theoretical and normative implications. Theoretically, a discourse of state personhood is completely unnecessary to understand world politics. Normatively, by tightly linking personhood and responsibility, some of the authors obscure important dimensions of responsibility to and respect for the non-human world.
MIND the gap: an astroglial perspective on barrier regulation
Authors: Savidge Tor C.
Published: April 2008

The blood–brain barrier (BBB) is a specialized tissue interface that provides an important homeostatic and immunosurveillance role in the CNS. Unlike most microvascular tissues, which readily promote paracellular passage of solutes and macromolecules, the BBB is more analogous to polarized mucosal epithelia that restrict such permeability in order to prevent disease onset. Recent transgenic ablation studies have demonstrated that the BBB and mucosal tissues also share a requirement for astroglial-regulated barrier integrity. This review highlights the emerging concept that astroglia regulate barrier function at markedly different tissue interfaces. It also explores possible lessons that might be learnt by adopting epithelial model paradigms of the BBB. For example, novel glial-derived S-nitrosylation signals that regulate intestinal permeability in the digestive tract might provide new mechanistic insights into the function of the BBB. A better understanding of such universal mechanisms for barrier regulation will facilitate novel therapeutic strategies that target permeability disorders at CNS and mucosal tissue interfaces.
Strategic Biopharmaceutical Portfolio Development: An Analysis of Constraint‐Induced Implications
Authors: George Edmund D. , Farid Suzanne S.
Published: April 2008

Optimizing the structure and development pathway of biopharmaceutical drug portfolios are core concerns to the developer that come with several attached complexities. These include strategic decisions for the choice of drugs, the scheduling of critical activities, and the possible involvement of third parties for development and manufacturing at various stages for each drug. Additional complexities that must be considered include the impact of making such decisions in an uncertain environment. Presented here is the development of a stochastic multi‐objective optimization framework designed to address these issues. The framework harnesses the ability of Bayesian networks to characterize the probabilistic structure of superior decisions via machine learning and evolve them to multi‐objective optimality. Case studies that entailed three‐ and five‐drug portfolios alongside a range of cash flow constraints were constructed to derive insight from the framework where results demonstrate that a variety of options exist for formulating nondominated strategies in the objective space considered, giving the manufacturer a range of pursuable options. In all cases limitations on cash flow reduce the potential for generating profits for a given probability of success. For the sizes of portfolio considered, results suggest that naïvely applying strategies optimal for a particular size of portfolio to a portfolio of another size is inappropriate. For the five‐drug portfolio the most preferred means for development across the set of optimized strategies is to fully integrate development and commercial activities in‐house. For the three‐drug portfolio, the preferred means of development involves a mixture of in‐house, outsourced, and partnered activities. Also, the size of the portfolio appears to have a larger impact on strategy and the quality of objectives than the magnitude of cash flow constraint.
Cleaning Characterization of Protein Drug Products Using UV‐vis Spectroscopy
Authors: Rathore Nitin , Qi Wei , Ji Wenchang
Published: April 2008

This study uses on‐line absorbance monitoring to evaluate cleanability of protein drug products. Characterization and validation of equipment cleanliness is a key requirement for a biopharmaceutical facility. A manufacturing‐scale cleaning cycle has to be developed and validated for its ability to clean all of the equipment parts for a given soil. Cleaning validation in a multiproduct fill‐finish facility could benefit from using a worst‐case‐based approach that involves validating the cleaning process for the most difficult to clean product. Such an approach minimizes the number of required validation runs. Scaled‐down cleaning evaluations can provide helpful information for evaluating multiple products and determine the worst case. This study presents a simple and rapid technique for bench‐scale characterization of cleanability of protein drug products. On‐line A280 (UV absorbance at 280 nm) measurements are performed using a fiber optic probe, and the data are used to establish the dynamics of protein dissolution in cleaning solution. The model not only helps to estimate cleaning time of different formulated proteins (and peptides) but also provides insights into the kinetics of cleaning under different thermal and chemical conditions. Protein product degradation during cleaning is also evaluated through gel electrophoresis. Such information is useful in designing new cleaning cycles. While the study is performed using drug products, the model as well as the findings are also applicable for characterization of final purified bulk soils relevant to bulk drug manufacturing.
Capillary retention of colloids in unsaturated porous media
Authors: Gao Bin , Steenhuis Tammo S. , Zevi Yuniati , Morales Veronica L. , Nieber John L. , Richards Brian K. , McCarthy John F. , Parlange J.‐Yves
Published: April 2008

Understanding colloid transport behavior in unsaturated porous media is important because mobile colloid‐contaminant complexes and colloidal pathogens can degrade groundwater quality. Visual evidence suggests that colloids are retained at the air‐water meniscus‐solid (AWmS) interface in unsaturated porous media, but there is no quantitative theoretical explanation of this retention mechanism to date. A theoretical study is presented here to quantify energy potentials represented by capillary forces on colloids at the AWmS interface in unsaturated porous media. Our calculations indicate that the capillary energy potentials for colloids retained in films or at the AWmS interface range from 107 to 108 kt, which are several orders greater than the Derjaguin‐Landau‐Verwey‐Overbeek energy potentials. Capillary forces for colloids at the AWmS interface can be decomposed into a force that pushes the colloid back in the bulk solution and one that pins the colloid against the surface of the grain. A friction force generated between the colloid and grain can prevent the colloids from moving back into solution. When drag forces can be ignored, colloids will remain at the AWmS interface as long as the static friction coefficient is greater than the tangent of the water‐grain contact angle. It is independent of the surface tension.
Spatial modeling of land cover change and watershed response using Markovian cellular automata and simulation
Authors: Marshall Eric , Randhir Timothy O.
Published: April 2008

A continued challenge in watershed management is information related to future land cover and its impact on watersheds. Changes in land cover can have significant impact on the quality and quantity of water resources, both spatially and temporally. This study evaluates potential implications of land cover change on the hydrology of a regional watershed. Land cover change is evaluated by using Markov Chain analysis and Cellular Automation to assess future land cover based on transitional probabilities and spatial influences. The hydrology of the watershed is simulated using a continuous time simulation model. The land cover change was found to be significant in the watershed with increased urbanization and loss of agricultural and forest cover. Land cover change increased overall surface runoff, stream flow, and sediment loading. Potential land cover changes impact the timing and magnitude of seasonal events. In addition to temporal variation in impacts, spatial impacts varied among subwatersheds and administrative boundaries. Opportunities were identified for mitigating the impacts of land cover change through best management practices and policies that incorporate watershed‐scale information to reduce impacts of changing in land cover on water quantity and quality.
Revisiting atmospheric dust export to the Southern Hemisphere ocean: Biogeochemical implications
Authors: Wagener Thibaut , Guieu Cécile , Losno Rémi , Bonnet Sophie , Mahowald Natalie
Published: April 2008

Aerosol concentrations in the Southern Hemisphere are largely undersampled. This study presents a chemical and physical description of dust particles collected on board research vessels in the southeast Pacific (SEPS) and the Southern Ocean (SOKS). Concentrations of dust were 6.1 ± 2.4 ng m−3 for SEPS and 13.0 ± 6.3 ng m−3 for SOKS. Dust fluxes, derived from those concentrations, were 9.9 ± 3.7 μg m−2 d−1 for SEPS and 38 ± 14 μg m−2 d−1 for SOKS and are shown to be representative of actual fluxes in those areas. Dust and iron deposition are up to 2 orders of magnitude lower than former predictions. A map of dust deposition on the Southern Hemisphere is proposed by incorporating those in situ measurements into a dust model. This study confirms that dust deposition is not the dominant source of iron to the large high‐nutrient low‐chlorophyll Southern Ocean.
Implications of the carbon cycle steady state assumption for biogeochemical modeling performance and inverse parameter retrieval
Authors: Carvalhais Nuno , Reichstein Markus , Seixas Júlia , Collatz G. James , Pereira João Santos , Berbigier Paul , Carrara Arnaud , Granier André , Montagnani Leonardo , Papale Dario , Rambal Serge , Sanz María José , Valentini Riccardo
Published: April 2008

We analyze the impacts of the steady state assumption on inverse model parameter retrieval from biogeochemical models. An inverse model parameterization study using eddy covariance CO2 flux data was performed with the Carnegie Ames Stanford Approach (CASA) model under conditions of strict and relaxed carbon cycle steady state assumption (CCSSA) in order to evaluate both the robustness of the model's structure for the simulation of net ecosystem carbon fluxes and the assessment of the CCSSA effects on simulations and parameter estimation. Net ecosystem production (NEP) measurements from several eddy covariance sites were compared with NEP estimates from the CASA model driven by local weather station climate inputs as well as by remotely sensed fraction of photosynthetically active radiation absorbed by vegetation and leaf area index. The parameters considered for optimization are directly related to aboveground and belowground modeled responses to temperature and water availability, as well as a parameter (η) that relaxed the CCSSA in the model, allowing for site level simulations to be initialized either as net sinks or sources. A robust relationship was observed between NEP observations and predictions for most of the sites through the range of temporal scales considered (daily, weekly, biweekly, and monthly), supporting the conclusion that the model structure is able to capture the main processes explaining NEP variability. Overall, relaxing CCSSA increased model efficiency (21%) and decreased normalized average error (−92%). Intersite variability was a major source of variance in model performance differences between fixed (CCSSAf) and relaxed (CCSSAr) CCSSA conditions. These differences were correlated with mean annual NEP observations, where an average increase in modeling efficiency of 0.06 per 100 g C m−2 a−1 (where a is years) of NEP is observed (α < 0.003). The parameter η was found to be a key parameter in the optimization exercise, generating significant model efficiency losses when removed from the initial parameter set and parameter uncertainties were significantly lower under CCSSAr. Moreover, modeled soil carbon stocks were generally closer to observations once the steady state assumption was relaxed. Finally, we also show that estimates of individual parameters are affected by the steady state assumption. For example, estimates of radiation‐use efficiency were strongly affected by the CCSSAf indicating compensation effects for the inadequate steady state assumption, leading to effective and thus biased parameters. Overall, the importance of model structural evaluation in data assimilation approaches is thus emphasized.
Wind forced low frequency variability of the East Australia Current
Authors: Hill K. L. , Rintoul S. R. , Coleman R. , Ridgway K. R.
Published: April 2008

A 62 year record of temperature and salinity from a coastal station off southeast Australia shows a strong positive trend and quasi‐decadal variability but the cause of the observed changes has not been explained. The temperature and salinity variations are highly correlated. The increase in temperature and salinity with time agrees closely with the mean meridional gradient of water properties along the continental slope, suggesting that changes in strength of the poleward extension of the East Australian Current are responsible for the observed variability. Interannual temperature and salinity changes are correlated (r = 0.7) with basin‐scale winds and with transport through the Tasman Sea estimated from Island Rule, with the changes at the western boundary lagging the wind forcing by three years. We conclude that the trend and decadal variability in the coastal temperature and salinity record reflect the response of the subtropical gyre and western boundary current to basin‐scale wind forcing.
Study of reconnection‐associated multiscale fluctuations with Cluster and Double Star
Authors: Vörös Z. , Nakamura R. , Sergeev V. , Baumjohann W. , Runov A. , Zhang T. L. , Volwerk M. , Takada T. , Jankovičová D. , Lucek E. , Rème H.
Published: April 2008

The objective of the paper is to asses the specific spectral scaling properties of magnetic reconnection associated fluctuations/turbulence at the earthward and tailward outflow regions observed simultaneously by the Cluster and Double Star (TC‐2) spacecraft on 26 September 2005. Systematic comparisons of spectral characteristics, including variance anisotropy and scale‐dependent spectral anisotropy features in wave vector space were possible due to the well‐documented reconnection events, occurring between the positions of Cluster (X = −14–16 Re) and TC‐2 (X = −6.6 Re). Another factor of key importance is that the magnetometers on the spacecraft are similar. The comparisons provide further evidence for asymmetry of physical processes in earthward/tailward reconnection outflow regions. Variance anisotropy and spectral anisotropy angles estimated from the multiscale magnetic fluctuations in the tailward outflow region show features which are characteristic for magnetohydrodynamic cascading turbulence in the presence of a local mean magnetic field. The multiscale magnetic fluctuations in the earthward outflow region are not only exhibiting more power, lack of variance, and scale‐dependent anisotropies but also are having larger anisotropy angles. In this region the magnetic field is more dipolar and the main processes driving turbulence are flow breaking/mixing, perhaps combined with turbulence ageing and noncascade‐related multiscale energy sources.
The 2002–03 Etna explosive activity: Tephra dispersal and features of the deposits
Authors: Andronico Daniele , Scollo Simona , Caruso Simona , Cristaldi Antonio
Published: April 2008

The onset of Mt. Etna's 2002–03 eruption was marked by intense explosive activity beginning on 27 October 2002 and persisting until 30 December. This phase of activity produced abundant ash emission that impacted the local economy and air traffic. Thereafter, explosive activity declined with the eruption ceasing on 28 January 2003. In this paper, we present field data collected during the eruption and use these to obtain input data for tephra dispersal model. This was applied, after validation, to extrapolate the total distribution of the deposits emplaced during the explosive activity. Detailed sampling of fallout deposits was completed on 27, 28, 31 October and 4 November. This enabled construction of isomass maps and calculation of the erupted mass. Grain‐size analysis of all collected samples was used to reconstruct the total grain‐size distribution which displays a peak at 0.5 Φ. Column height was estimated at 3.3–7 km by combining barometrical altimeter data during over‐flights with the analysis of images and videos. This was used to estimate a total erupted mass of 4.4 ± 0.6 × 1010 kg. Simulations showed that the deposit was significantly affected by variations in wind direction and mass eruption rate, with deposits being dispersed mainly on the E sector of the volcano due to a dominant easterly wind. Our study underlines that basaltic volcanoes, such as Etna, can produce huge amounts of ash, as well as lava, and that an improvement in the knowledge of dispersal processes during prolonged explosive activity is required to better mitigate the associated hazards.
Effects of radiative cooling on the tropical convective response to sea surface temperature: 2‐D large domain cumulus ensemble simulations
Authors: Sui C.‐H. , Li X. , Ho C.‐H. , Lau K.‐M.
Published: April 2008

The effects of radiative cooling on the tropical convective response to sea surface temperature (SST) are investigated using a series of two‐dimensional large domain cloud‐resolving simulations. The experiments are designed with an imposed warm‐pool SST at 2.5°C, 3.5°C, and 4.5°C higher than the cold‐pool SST, which is specified at 26°C. The area ratio of the model cold pool to the warm pool is set to 2.2. It is observed that the warm‐pool convection intensifies when the SST difference between the warm and cold pools increases from 2.5°C to 3.5°C, whereas the warm‐pool convection strength does not significantly change when the SST difference increases from 3.5°C to 4.5°C, which is qualitatively consistent with the observations. The analysis of the atmospheric heat budgets shows that the cap on the development of convection over the warm pool is due to a radiative cooling over the cold pool that has a small variability. The cloud‐resolving model simulations indicate that the area of the radiatively driven subsidence expands to produce an enhanced mass exchange between the warm and cold pools in response to the enhanced SST difference between them. This acts against the tendency for increased clouds by the enhanced upward mass flux in response to the warmer SST over the warm pool; significantly stronger SST differences between the two pools (e.g., ≥3.5°C in the cloud‐resolving model) do not proportionally produce further intensive convection activities over the warm pool.
Tropospheric Emission Spectrometer nadir spectral radiance comparisons
Authors: Shephard Mark W. , Worden Helen M. , Cady‐Pereira Karen E. , Lampel Michael , Luo Mingzhao , Bowman Kevin W. , Sarkissian Edwin , Beer Reinhard , Rider David M. , Tobin David C. , Revercomb Henry E. , Fisher Brendan M. , Tremblay Denis , Clough Shepard A. , Osterman Gregory B. , Gunson Michael
Published: April 2008

The fundamental measurement of the Tropospheric Emission Spectrometer (TES) on board the Aura spacecraft is upwelling infrared spectral radiances. Accurate TES retrievals of surface and atmospheric parameters such as trace gas amounts critically depend on well‐calibrated radiance spectra. On‐orbit TES nadir observations were evaluated using carefully selected, nearly coincident spectral radiance measurements from Atmospheric Infrared Sounder (AIRS) on Aqua and special scanning high‐resolution interferometer sounder (SHIS) underflights. Modifications to the L1B calibration algorithms for TES version 2 data resulted in significant improvements for the TES‐AIRS comparisons. The comparison of TES with SHIS (adjusted for geometric differences) show mean and standard deviation differences of less than 0.3 K at warmer brightness temperatures of 290–295 K. The TES/SHIS differences are less than 0.4 K at brightness temperatures of 265–270 K. There are larger TES/SHIS comparison differences for higher‐frequency TES 1A1 filter, which has less upwelling radiance signal. The TES/AIRS comparisons show mean differences of less than 0.3 K at 290–295 K and less than 0.5 K at 265–270 K with standard deviation less than 0.6 K for the majority of the spectral regions and brightness temperature range. A procedure to warm up the optical bench for better alignment in December 2005 gave a fourfold increase in the signal‐to‐noise ratio at higher frequency ranges. Recent results from a long‐term comparison of TES sea surface temperature (SST) observations with the Reynolds optimally interpolated (ROI) SST product demonstrates TES radiometric stability.
Sources of particulate matter in the northeastern United States in summer: 2. Evolution of chemical and microphysical properties
Authors: Brock C. A. , Sullivan A. P. , Peltier R. E. , Weber R. J. , Wollny A. , de Gouw J. A. , Middlebrook A. M. , Atlas E. L. , Stohl A. , Trainer M. K. , Cooper O. R. , Fehsenfeld F. C. , Frost G. J. , Holloway J. S. , Hübler G. , Neuman J. A. , Ryerson T. B. , Warneke C. , Wilson J. C.
Published: April 2008

Measurements of aerosol particle size distributions and composition and of trace and reactive gas mixing ratios were made on the NOAA WP‐3D aircraft downwind of mixed urban/industrial sources in the northeastern United States (U.S.). These measurements were made in noncloudy air during July and August 2004, under conditions where cloud processing was not likely to play an important role in oxidation chemistry. Under these conditions, particulate sulfate was found to be produced with an exponential time constant of ∼3.5 d from the gas‐phase oxidation of SO2, which was ubiquitous but inhomogeneously distributed in the pollution plumes. When submicron particle mass concentrations exceeded 15 μg m−3, sulfate and associated ammonium dominated the composition; at lower mass concentrations particulate organic matter (OM) dominated. Since most of the urban plumes sampled contained substantial SO2 from nearby industrial sources, the apportionment of aerosol mass between OM and sulfate compounds under noncloudy conditions was governed largely by the differences between the oxidation timescales of SO2 and those of precursor volatile organic compounds (VOCs) relative to their transport time. These differences in oxidation timescales may explain much of the variability in previously published OM/sulfate ratios for this region. These observations indicate that even with higher‐than‐expected secondary OM formation, in the northeastern U.S. the potential inorganic particulate mass from SO2 emissions significantly exceeds the potential secondary OM from anthropogenic VOC emissions.
Sources of particulate matter in the northeastern United States in summer: 1. Direct emissions and secondary formation of organic matter in urban plumes
Authors: de Gouw J. A. , Brock C. A. , Atlas E. L. , Bates T. S. , Fehsenfeld F. C. , Goldan P. D. , Holloway J. S. , Kuster W. C. , Lerner B. M. , Matthew B. M. , Middlebrook A. M. , Onasch T. B. , Peltier R. E. , Quinn P. K. , Senff C. J. , Stohl A. , Sullivan A. P. , Trainer M. , Warneke C. , Weber R. J. , Williams E. J.
Published: April 2008

Ship and aircraft measurements of aerosol organic matter (OM) and water‐soluble organic carbon (WSOC) were made in fresh and aged pollution plumes from major urban areas in the northeastern United States in the framework of the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) study. A large part of the variability in the data was quantitatively described by a simple parameterization from a previous study that uses measured mixing ratios of CO and either the transport age or the photochemical age of the sampled air masses. The results suggest that OM was mostly due to secondary formation from anthropogenic volatile organic compound (VOC) precursors in urban plumes. Approximately 37% of the secondary formation can be accounted for by the removal of aromatic precursors using newly published particulate mass yields for low‐NOx conditions, which are significantly higher than previous results. Of the secondary formation, 63% remains unexplained and is possibly due to semivolatile precursors that are not measurable by standard gas chromatographic methods. The observed secondary OM in urban plumes may account for 35% of the total source of OM in the United States and 8.5% of the global OM source. OM is an important factor in climate and air quality issues, but its sources and formation mechanisms remain poorly quantified.
Aerosol hygroscopicity and cloud droplet activation of extracts of filters from biomass burning experiments
Authors: Carrico Christian M. , Petters Markus D. , Kreidenweis Sonia M. , Collett Jeffrey L. , Engling Guenter , Malm William C.
Published: April 2008

In this laboratory closure study, we compare sub‐ and supersaturated water uptake properties for aerosol particles possessing a range of hygroscopicity. Measurements for water sub‐saturated conditions used a hygroscopic tandem differential mobility analyzer (HTDMA). Simultaneously, measurements of particle critical supersaturation were conducted on the same sample stream with a continuous flow cloud condensation nuclei (CCN) counter. For these experiments, we used filter‐collected samples of biomass smoke generated in the combustion of two common wildland fire fuels, western sagebrush and Alaskan duff core. Extractions of separate sections of the filter were performed using two solvents, ultrapure water and methanol. The extracts were subsequently atomized, producing aerosols having a range of hygroscopic responses. HTDMA and CCN measurements were fit to a single‐parameter model of water uptake, in which the fit parameter is denoted κ, the hygroscopicity parameter. Here, for the four extracts we observed mean values of the hygroscopicity parameter of 0.06 < κ < 0.30, similar to the range found previously for numerous pure organic compounds. Particles generated from the aqueous extracts of the filters had consistently larger κ than methanol extracts, while western sagebrush extract aerosols κ exceeded those from Alaskan duff core. HTDMA‐ and CCN‐derived values of κ for each experiment agreed within approximately 20%. Applicability of the κ‐parameterization to other multicomponent aerosols relevant to the atmosphere remains to be tested.
A satellite‐based assessment of transpacific transport of pollution aerosol
Authors: Yu Hongbin , Remer Lorraine A. , Chin Mian , Bian Huisheng , Kleidman Richard G. , Diehl Thomas
Published: April 2008

It has been well documented that pollution and dust from east Asia can be transported across the North Pacific basin, reaching North America and beyond. In this study, we assess the transpacific transport of “pollution aerosol” (defined as a mixture of aerosols from urban/industrial pollution and biomass burning) by taking advantage of the much improved measurement accuracy and enhanced new capabilities of satellite sensors in recent years. A 4‐year (2002 to 2005) climatology of optical depth for pollution aerosol was generated from Moderate Resolution Imaging Spectroradiometer (MODIS) observations of fine‐ and coarse‐mode aerosol optical depths. The pollution aerosol mass loading and fluxes were then calculated using measurements of the dependence of aerosol mass extinction efficiency on relative humidity and of aerosol vertical distributions from field campaigns and available satellite observations in the region. We estimated that about 18 Tg/a pollution aerosol is exported from east Asia to the northwestern Pacific Ocean, of which about 25% reaches the west coast of North America. The imported flux of 4.4 Tg/a to North America is equivalent to about 15% of local emissions from the United States and Canada. The pollution fluxes are largest in spring and smallest in summer. For the period we have examined the strongest export and import of pollution particulates occurred in 2003, largely because of record intense Eurasia boreal forest fires in spring and summer. The overall uncertainty of pollution fluxes is estimated at a factor of 2. Simulations by the Goddard Chemistry Aerosol Radiation and Transport (GOCART) and Global Modeling Initiative (GMI) models agree quite well with the satellite‐based estimates of annual and latitude‐integrated fluxes, with larger model‐satellite differences in latitudinal and seasonal variations of fluxes.
Characterization of atmospheric aerosols using MFRSR measurements
Authors: Alexandrov Mikhail D. , Lacis Andrew A. , Carlson Barbara E. , Cairns Brian
Published: April 2008

Measurements by multifilter rotating shadowband radiometers (MFRSRs) constitute a valuable global data set with contributions from hundreds of instruments deployed worldwide. The geographical coverage of MFRSR networks is complementary to that of AERONET and often provides better spatial density of measurement sites, especially in the United States. We describe our recently updated analysis algorithm for MFRSR data that allows partitioning of the spectral aerosol optical depth (AOD) into fine and coarse mode AOD and retrieval of the fine mode effective radius. Our recent sensitivity study demonstrated that for a typical measurement accuracy 0.01 of AOD, the trade‐offs between the spectral aerosol extinction and NO2 absorption in the visible range effectively prevent unambiguous retrieval of NO2 column from MFRSR data and may also bias aerosol size distribution retrievals. This has prompted us to adopt a new retrieval approach, which utilizes climatological NO2 (based on SCIAMACHY satellite retrievals) and uses column ozone from TOMS measurements. The performance of this new approach was evaluated using the long‐term data set from the Southern Great Plains (SGP) site operated by the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program. We present a detailed intercomparison of total, fine, and coarse mode AOD and fine mode effective radius between two MFRSRs located at the SGP's Central Facility and with the correlative AERONET Sun‐sky inversion results (Version 2) derived from a collocated CIMEL Sun photometer. The comparison between two MFRSRs demonstrated good consistency of both the measurements and the analysis. Agreement with AERONET inversions is remarkably good, in that differences in AOD components do not exceed the expected measurement accuracy of 0.01, while the retrieved values of fine mode effective radius show no relative bias and only 0.03 μm random error (standard deviation of the differences). We show that if only data with large enough AOD (more than 0.06 at 870 nm) are selected, this error is reduced by a factor of two, becoming about 10% of a typical fine mode effective radius value.
Changes in the soil C cycle at the arid‐hyperarid transition in the Atacama Desert
Authors: Ewing S. A. , Macalady J. L. , Warren‐Rhodes K. , McKay C. P. , Amundson R.
Published: April 2008

We examined soil organic C (OC) turnover and transport across the rainfall transition from a biotic, arid site to a largely abiotic, hyperarid site. With this transition, OC concentrations decrease, and C cycling slows precipitously, both in surface horizons and below ground. The concentration and isotopic character of soil OC across this transition reflect decreasing rates of inputs, decomposition, and downward transport. OC concentrations in the arid soil increase slightly with depth in the upper meter, but are generally low and variable (∼0.05%; total inventory of 1.82 kg m−2); OC‐Δ14C values decrease from modern (+7‰) to very 14C‐depleted (−966‰) with depth; and OC‐δ13C values are variable (−23.7‰ to –14.1‰). Using a transport model, we show that these trends reflect relatively rapid cycling in the upper few centimeters, and spatially variable preservation of belowground OC from root inputs, possibly during a previous, wetter climate supporting higher soil OC concentrations. In the driest soil, the OC inventory is the lowest among the sites (0.19 kg m−2), and radiocarbon values are 14C‐depleted (−365‰ to –696‰) but show no trend with depth, indicating belowground OC inputs and long OC residence times throughout the upper meter (104 y). A distinct depth trend in δ13C values and OC/ON values within the upper 40 cm at the driest site may reflect photochemical alteration of organic matter at the soil surface, combined with limited subsurface decomposition and downward transport. We argue that while root inputs are preserved at the wetter sites, C cycling in the most hyperarid soil occurs through infrequent, rapid dissolved transport of highly photodegraded organic matter during rare rain events, each followed by a pulse of decomposition and subsequent prolonged drought. These belowground inputs are likely a primary control on the character, activity, and depth distribution of small microbial populations. While the lack of water is the dominant control on C cycling, very low C/N ratios of organic matter suggest that when rainfall occurs, hyperarid soils are effectively C limited. The preservation of fossil root fragments in the sediment beneath the driest soil indicates that wetter climate conditions preceded formation of this soil, and that vadose zone microbial activity has been extremely limited for the past 2 My.
Characterization of ICESat/GLAS waveforms over terrestrial ecosystems: Implications for vegetation mapping
Authors: Neuenschwander Amy L. , Urban Timothy J. , Gutierrez Roberto , Schutz Bob E.
Published: April 2008

ICESat/GLAS laser altimetry data have become increasingly utilized for vegetation mapping and canopy characterization. Waveform shapes are dependent upon complex relationships between several factors on the illuminated surface including topography, brightness, clouds, satellite pointing, laser energy, footprint size, shape and orientation, and vegetation height and position within the footprint. However, the understanding of these factors is presently unclear. We first examine the simple case introduced into the GLAS waveform by laser retro‐reflectors placed at White Sands, New Mexico, as a proxy for vegetation height detection. We observed that the 1/e2 energy distribution was only an approximation and that strong reflectors contribute to the returned energy beyond the estimated parameters. The precise position of the corner cube reflector within each footprint coupled with laser pointing angle is an important factor on the estimated vegetation height. Next we examine the implications of vegetation structure and surface topography on the waveform shape and derived elevations, compared with data from an airborne lidar system at Freeman Ranch, Texas, which has been targeted by ICESat since 2005. Small‐footprint waveforms were combined to synthesize the energy distribution within a GLAS footprint, and they compared well (>90% correlation) to the GLAS waveforms. The GLAS‐estimated canopy heights compared well (μ = 0.21 m) to the airborne lidar estimates during leaf‐on conditions. However, GLAS‐estimated ground elevations are biased by ∼1 m compared to airborne lidar in vegetated regions. In this landscape, the GLAS‐energy ratio (canopy‐to‐ground energy) was a good indicator (R2 = 0.74) of the amount of woody cover within the footprint.
Beyond Thiem: A new method for interpreting large scale pumping tests in heterogeneous aquifers
Authors: Schneider C. L. , Attinger S.
Published: April 2008

The heterogeneous character of aquifers prevents a consistent interpretation of pumping tests based on Thiem's formula which has been developed for homogeneous aquifers. We present a new mathematical method for interpreting an ensemble and single large scale pumping tests in heterogeneous confined isotropic aquifers. By combining a multiscale technique called Coarse Graining with Renormalization Group analysis, we derive an explicit formula for the coarse grained aquifer transmissivity. The coarse grained transmissivity is dependent on the radial distance from the well. Close to the well, it equals the local transmissivity in single pumping tests and the harmonic mean of the heterogeneous transmissivity field in ensemble pumping tests. In the far field of the well the coarse grained transmissivity approaches the geometric mean. The transition between both regimes is mainly determined by the transmissivities correlation length. This relation is used for an inversely estimate of the statistical properties of the transmissivity such as its geometric mean. In addition, this method allows for determining aquifer structures characterized by a correlation length from a single pumping test, while the variance can be estimated from pumping tests with ensemble averaged hydraulic heads.