Showing papers by "Florida State University published in 2008"

The CMS experiment at the CERN LHC

Abstract: The Compact Muon Solenoid (CMS) detector is described. The detector operates at the Large Hadron Collider (LHC) at CERN. It was conceived to study proton-proton (and lead-lead) collisions at a centre-of-mass energy of 14 TeV (5.5 TeV nucleon-nucleon) and at luminosities up to 10(34)cm(-2)s(-1) (10(27)cm(-2)s(-1)). At the core of the CMS detector sits a high-magnetic-field and large-bore superconducting solenoid surrounding an all-silicon pixel and strip tracker, a lead-tungstate scintillating-crystals electromagnetic calorimeter, and a brass-scintillator sampling hadron calorimeter. The iron yoke of the flux-return is instrumented with four stations of muon detectors covering most of the 4 pi solid angle. Forward sampling calorimeters extend the pseudo-rapidity coverage to high values (vertical bar eta vertical bar <= 5) assuring very good hermeticity. The overall dimensions of the CMS detector are a length of 21.6 m, a diameter of 14.6 m and a total weight of 12500 t.

Focus on Formative Feedback

Abstract: This article reviews the corpus of research on feedback, with a focus on formative feedback—defined as information communicated to the learner that is intended to modify his or her thinking or behavior to improve learning According to researchers, formative feedback should be nonevaluative, supportive, timely, and specific Formative feedback is usually presented as information to a learner in response to some action on the learner’s part It comes in a variety of types (eg, verification of response accuracy, explanation of the correct answer, hints, worked examples) and can be administered at various times during the learning process (eg, immediately following an answer, after some time has elapsed) Finally, several variables have been shown to interact with formative feedback’s success at promoting learning (eg, individual characteristics of the learner and aspects of the task) All of these issues are discussed This review concludes with guidelines for generating formative feedback

The worst-case execution-time problem—overview of methods and survey of tools

Abstract: The determination of upper bounds on execution times, commonly called worst-case execution times (WCETs), is a necessary step in the development and validation process for hard real-time systems. This problem is hard if the underlying processor architecture has components, such as caches, pipelines, branch prediction, and other speculative components. This article describes different approaches to this problem and surveys several commercially available tools1 and research prototypes.

Macromolecular Crowding and Confinement: Biochemical, Biophysical, and Potential Physiological Consequences*

Abstract: Expected and observed effects of volume exclusion on the free en- ergy of rigid and flexible macromolecules in crowded and confined systems, and consequent effects of crowding and confinement on macromolecular reaction rates and equilibria are summarized. Find- ings from relevant theoretical/simulation and experimental literature published from 2004 onward are reviewed. Additional complexity arising from the heterogeneity of local environments in biological media, and the presence of nonspecific interactions between macro- molecules over and above steric repulsion, are discussed. Theoretical and experimental approaches to the characterization of crowding- and confinement-induced effects in systems approaching the com- plexity of living organisms are suggested.

AWTY (are we there yet

Abstract: Summary: A key element to a successful Markov chain Monte Carlo (MCMC) inference is the programming and run performance of the Markov chain. However, the explicit use of quality assessments of the MCMC simulations—convergence diagnostics—in phylogenetics is still uncommon. Here, we present a simple tool that uses the output from MCMC simulations and visualizes a number of properties of primary interest in a Bayesian phylogenetic analysis, such as convergence rates of posterior split probabilities and branch lengths. Graphical exploration of the output from phylogenetic MCMC simulations gives intuitive and often crucial information on the success and reliability of the analysis. The tool presented here complements convergence diagnostics already available in other software packages primarily designed for other applications of MCMC. Importantly, the common practice of using trace-plots of a single parameter or summary statistic, such as the likelihood score of sampled trees, can be misleading for assessing the success of a phylogenetic MCMC simulation. Availability: The program is available as source under the GNU General Public License and as a web application at http://ceb.scs.fsu.edu/awty Contact: jwilgenb@scs.fsu.edu

Beam dynamics in PT symmetric optical lattices.

Abstract: The possibility of parity-time (PT) symmetric periodic potentials is investigated within the context of optics. Beam dynamics in this new type of optical structures is examined in detail for both one- and two-dimensional lattice geometries. It is shown that PT periodic structures can exhibit unique characteristics stemming from the nonorthogonality of the associated Floquet-Bloch modes. Some of these features include double refraction, power oscillations, and eigenfunction unfolding as well as nonreciprocal diffraction patterns.

Ecological consequences of genetic diversity.

Abstract: Understanding the ecological consequences of biodiversity is a fundamental challenge. Research on a key component of biodiversity, genetic diversity, has traditionally focused on its importance in evolutionary processes, but classical studies in evolutionary biology, agronomy and conservation biology indicate that genetic diversity might also have important ecological effects. Our review of the literature reveals significant effects of genetic diversity on ecological processes such as primary productivity, population recovery from disturbance, interspecific competition, community structure, and fluxes of energy and nutrients. Thus, genetic diversity can have important ecological consequences at the population, community and ecosystem levels, and in some cases the effects are comparable in magnitude to the effects of species diversity. However, it is not clear how widely these results apply in nature, as studies to date have been biased towards manipulations of plant clonal diversity, and little is known about the relative importance of genetic diversity vs. other factors that influence ecological processes of interest. Future studies should focus not only on documenting the presence of genetic diversity effects but also on identifying underlying mechanisms and predicting when such effects are likely to occur in nature.

Deliberate practice and acquisition of expert performance: a general overview.

Abstract: Traditionally, professional expertise has been judged by length of experience, reputation, and perceived mastery of knowledge and skill. Unfortunately, recent research demonstrates only a weak relationship between these indicators of expertise and actual, observed performance. In fact, observed performance does not necessarily correlate with greater professional experience. Expert performance can, however, be traced to active engagement in deliberate practice (DP), where training (often designed and arranged by their teachers and coaches) is focused on improving particular tasks. DP also involves the provision of immediate feedback, time for problem-solving and evaluation, and opportunities for repeated performance to refine behavior. In this article, we draw upon the principles of DP established in other domains, such as chess, music, typing, and sports to provide insight into developing expert performance in medicine.

A simple and efficient method for the solid‐phase extraction of dissolved organic matter (SPE‐DOM) from seawater

Abstract: A simple protocol is presented for the solid-phase extraction of dissolved organic matter (SPE-DOM) from seawater using commercially prepacked cartridges. The method does not require major instrumentation and can be performed in the field. Modified styrene divinyl benzene polymer type sorbents (Varian PPL and ENV) and sorbents of a silica structure bonded with different hydrocarbon chains (Varian C8, C18, C18OH, and C18EWP) were considered. Except for C18OH, which heavily contaminated the samples, none of the sorbents leached significant amounts of dissolved organic carbon (DOC) or nitrogen (DON). Samples from the North Brazil shelf with strong mixing gradients of terrigenous and marine DOM were used to compare the various sorbents. PPL was the most efficient—on average, 62% of DOC was recovered as salt-free extracts. C18 was found to be most efficient among the silica-based sorbents, but it showed only two-thirds of the extraction efficiency of PPL. As indicated by [ 1 H]NMR, C/N, and δ 13 C analyses, PPL extracted a more representative proportion of DOM than C18. Therefore, PPL was used for comparative studies in the Gulf of Mexico and Antarctica. From brackish marsh and river waters, 65% and 62% of total DOC, respectively, could be extracted. For purely marine DOM in Antarctica and the deep sea, the extraction efficiency was lower (43% on average). The efficiency of the new method to isolate marine DOM is better than or similar to highly laborious methods. A further advantage is the complete desalination of the sample. The isolation of a major DOM fraction, which is salt-free, offers many possibilities to further characterize DOM by advanced analytical techniques.

Optical solitons in PT periodic potentials

Abstract: We investigate the effect of nonlinearity on beam dynamics in parity-time (PT) symmetric potentials. We show that a novel class of one- and two-dimensional nonlinear self-trapped modes can exist in optical PT synthetic lattices. These solitons are shown to be stable over a wide range of potential parameters. The transverse power flow within these complex solitons is also examined.

The increasing intensity of the strongest tropical cyclones

Abstract: Atlantic tropical cyclones are getting stronger on average, with a 30-year trend that has been related to an increase in ocean temperatures over the Atlantic Ocean and elsewhere. Over the rest of the tropics, however, possible trends in tropical cyclone intensity are less obvious, owing to the unreliability and incompleteness of the observational record and to a restricted focus, in previous trend analyses, on changes in average intensity. Here we overcome these two limitations by examining trends in the upper quantiles of per-cyclone maximum wind speeds (that is, the maximum intensities that cyclones achieve during their lifetimes), estimated from homogeneous data derived from an archive of satellite records. We find significant upward trends for wind speed quantiles above the 70th percentile, with trends as high as 0.3 +/- 0.09 m s(-1) yr(-1) (s.e.) for the strongest cyclones. We note separate upward trends in the estimated lifetime-maximum wind speeds of the very strongest tropical cyclones (99th percentile) over each ocean basin, with the largest increase at this quantile occurring over the North Atlantic, although not all basins show statistically significant increases. Our results are qualitatively consistent with the hypothesis that as the seas warm, the ocean has more energy to convert to tropical cyclone wind.

Suicidal Desire and the Capability for Suicide: Tests of the Interpersonal-Psychological Theory of Suicidal Behavior among Adults.

Abstract: The interpersonal-psychological theory of suicidal behavior (T. E. Joiner, 2005) proposes that an individual will not die by suicide unless he or she has both the desire to die by suicide and the ability to do so. Three studies test the theory's hypotheses. In Study 1, the interaction of thwarted belongingness and perceived burdensomeness predicted current suicidal ideation. In Study 2, greater levels of acquired capability were found among individuals with greater numbers of past attempts. Results also indicated that painful and provocative experiences significantly predicted acquired capability scores. In Study 3, the interaction of acquired capability and perceived burdensomeness predicted clinician-rated risk for suicidal behavior. Implications for the etiology, assessment, and treatment of suicidal behavior are discussed.

Improving the photostability of bright monomeric orange and red fluorescent proteins.

Abstract: All organic fluorophores undergo irreversible photobleaching during prolonged illumination. Although fluorescent proteins typically bleach at a substantially slower rate than many small-molecule dyes, in many cases the lack of sufficient photostability remains an important limiting factor for experiments requiring large numbers of images of single cells. Screening methods focusing solely on brightness or wavelength are highly effective in optimizing both properties, but the absence of selective pressure for photostability in such screens leads to unpredictable photobleaching behavior in the resulting fluorescent proteins. Here we describe an assay for screening libraries of fluorescent proteins for enhanced photostability. With this assay, we developed highly photostable variants of mOrange (a wavelength-shifted monomeric derivative of DsRed from Discosoma sp.) and TagRFP (a monomeric derivative of eqFP578 from Entacmaea quadricolor) that maintain most of the beneficial qualities of the original proteins and perform as reliably as Aequorea victoria GFP derivatives in fusion constructs.

Mangrove Production and Carbon sinks: A revision of global budget estimates

Abstract: results in a conservative estimate of 218 ± 72 Tg C a 1 . When using the best available estimates of various carbon sinks (organic carbon export, sediment burial, and mineralization), it appears that >50% of the carbon fixed by mangrove vegetation is unaccounted for. This unaccounted carbon sink is conservatively estimated at 112 ± 85 Tg C a 1 , equivalent in magnitude to 30–40% of the global riverine organic carbon input to the coastal zone. Our analysis suggests that mineralization is severely underestimated, and that the majority of carbon export from mangroves to adjacent waters occurs as dissolved inorganic carbon (DIC). CO2 efflux from sediments and creek waters and tidal export of DIC appear to be the major sinks. These processes are quantitatively comparable in magnitude to the unaccounted carbon sink in current budgets, but are not yet adequately constrained with the limited published data available so far.

Recurrent concussion and risk of depression in retired professional football players.

Abstract: GUSKIEWICZ, K. M., S. W. MARSHALL, J. BAILES, M. MCCREA, H. P. HARDING JR, A. MATTHEWS, J. R. MIHALIK, and R. C. CANTU. Recurrent Concussion and Risk of Depression in Retired Professional Football Players. Med. Sci. Sports Exerc., Vol. 39, No. 6, pp. 903–909, 2007. Purpose: The purpose of our study was to investigate the association between prior head injury and the likelihood of being diagnosed with clinical depression among retired professional football players with prior head injury exposure. Methods: A general health questionnaire, including information about prior injuries, the SF-36 (Short Form 36), and other markers for depression, was completed by 2552 retired professional football players with an average age of 53.8 (T 13.4) yr and an average professional football-playing career of 6.6 (T 3.6) yr. A second questionnaire focusing on mild cognitive impairment (MCI)-related issues was completed by a subset of 758 retired professional football players (50 yr and older). Results: Two hundred sixty-nine (11.1%) of all respondents reported having prior or current diagnosis of clinical depression. There was an association between recurrent concussion and diagnosis of lifetime depression (W 2 = 71.21, df =2 ,P G 0.005), suggesting that the prevalence increases with increasing concussion history. Compared with retired players with no history of concussion, retired players reporting three or more previous concussions (24.4%) were three times more likely to be diagnosed with depression; those with a history of one or two previous concussions (36.3%) were 1.5 times more likely to be diagnosed with depression. The analyses controlled for age, number of years since retirement, number of years played, physical component score on the SF-36, and diagnosed comorbidities such as osteoarthritis, coronary heart disease, stroke, cancer, and diabetes. Conclusion: Our findings suggest a possible link between recurrent sport-related concussion and increased risk of clinical depression. The findings emphasize the importance of understanding potential

Making choices impairs subsequent self-control: A limited-resource account of decision making, self-regulation, and active initiative.

Abstract: The current research tested the hypothesis that making many choices impairs subsequent self-control. Drawing from a limited-resource model of self-regulation and executive function, the authors hypothesized that decision making depletes the same resource used for self-control and active responding. In 4 laboratory studies, some participants made choices among consumer goods or college course options, whereas others thought about the same options without making choices. Making choices led to reduced self-control (i.e., less physical stamina, reduced persistence in the face of failure, more procrastination, and less quality and quantity of arithmetic calculations). A field study then found that reduced self-control was predicted by shoppers' self-reported degree of previous active decision making. Further studies suggested that choosing is more depleting than merely deliberating and forming preferences about options and more depleting than implementing choices made by someone else and that anticipating the choice task as enjoyable can reduce the depleting effect for the first choices but not for many choices.

Strategic resources and performance: a meta-analysis

Abstract: Resource-based theory (RBT) has emerged as a key perspective guiding inquiry into the determinants of organizational performance. Since the early 1990s, numerous studies have examined RBT's assertion that the extent to which organizations possess strategic resources is positively related to performance. Although many studies appear to support this assertion, there is no consensus regarding how strongly strategic resources relate to performance. To help resolve this issue, we meta-analyze 125 studies of RBT that collectively encompass over 29,000 organizations. Our conservative estimate is that the effect size of the strategic resources–performance relationship is rc = 0.22. Moderator tests suggest that the resources-performance link is stronger (1) when resources meet the criteria laid out in RBT and (2) for those performance measures that are not affected by potential value appropriation. When resources meet RBT's criteria and when performance measures are not affected by potential appropriation, the strength of the relationship grows to rc = 0.29. This suggests that the identification, development, and distribution of value from strategic resources should be a primary consideration for scholars, managers, and shareholders. Copyright © 2008 John Wiley & Sons, Ltd.

Four-Chamber Heart Modeling and Automatic Segmentation for 3-D Cardiac CT Volumes Using Marginal Space Learning and Steerable Features

Abstract: We propose an automatic four-chamber heart segmentation system for the quantitative functional analysis of the heart from cardiac computed tomography (CT) volumes. Two topics are discussed: heart modeling and automatic model fitting to an unseen volume. Heart modeling is a nontrivial task since the heart is a complex nonrigid organ. The model must be anatomically accurate, allow manual editing, and provide sufficient information to guide automatic detection and segmentation. Unlike previous work, we explicitly represent important landmarks (such as the valves and the ventricular septum cusps) among the control points of the model. The control points can be detected reliably to guide the automatic model fitting process. Using this model, we develop an efficient and robust approach for automatic heart chamber segmentation in 3D CT volumes. We formulate the segmentation as a two-step learning problem: anatomical structure localization and boundary delineation. In both steps, we exploit the recent advances in learning discriminative models. A novel algorithm, marginal space learning (MSL), is introduced to solve the 9-D similarity transformation search problem for localizing the heart chambers. After determining the pose of the heart chambers, we estimate the 3D shape through learning-based boundary delineation. The proposed method has been extensively tested on the largest dataset (with 323 volumes from 137 patients) ever reported in the literature. To the best of our knowledge, our system is the fastest with a speed of 4.0 s per volume (on a dual-core 3.2-GHz processor) for the automatic segmentation of all four chambers.

Petroleomics: Chemistry of the underworld

Abstract: Each different molecular elemental composition—e.g., CcHhNnOoSs—has a different exact mass. With sufficiently high mass resolving power (m/Δm50% ≈ 400,000, in which m is molecular mass and Δm50% is the mass spectral peak width at half-maximum peak height) and mass accuracy (<300 ppb) up to ≈800 Da, now routinely available from high-field (≥9.4 T) Fourier transform ion cyclotron resonance mass spectrometry, it is possible to resolve and identify uniquely and simultaneously each of the thousands of elemental compositions from the most complex natural organic mixtures, including petroleum crude oil. It is thus possible to separate and sort petroleum components according to their heteroatom class (NnOoSs), double bond equivalents (DBE = number of rings plus double bonds involving carbon, because each ring or double bond results in a loss of two hydrogen atoms), and carbon number. “Petroleomics” is the characterization of petroleum at the molecular level. From sufficiently complete characterization of the organic composition of petroleum and its products, it should be possible to correlate (and ultimately predict) their properties and behavior. Examples include molecular mass distribution, distillation profile, characterization of specific fractions without prior extraction or wet chemical separation from the original bulk material, biodegradation, maturity, water solubility (and oil:water emulsion behavior), deposits in oil wells and refineries, efficiency and specificity of catalytic hydroprocessing, “heavy ends” (asphaltenes) analysis, corrosion, etc.

Measuring and comparing evolvability and constraint in multivariate characters

Abstract: The Lande equation forms the basis for our understanding of the short-term evolution of quantitative traits in a multivariate context It predicts the response to selection as the product of an additive genetic variance matrix and a selection gradient The selection gradient approximates the force and direction of selection, and the genetic variance matrix quantifies the role of the genetic system in evolution Attempts to understand the evolutionary significance of the genetic variance matrix are hampered by the fact that the majority of the methods used to characterize and compare variance matrices have not been derived in an explicit theoretical context We use the Lande equation to derive new measures of the ability of a variance matrix to allow or constrain evolution in any direction in phenotype space Evolvability captures the ability of a population to evolve in the direction of selection when stabilizing selection is absent Conditional evolvability captures the ability of a population to respond to directional selection in the presence of stabilizing selection on other trait combinations We then derive measures of character autonomy and integration from these evolvabilities We study the properties of these measures and show how they can be used to interpret and compare variance matrices As an illustration, we show that divergence of wing shape in the dipteran family Drosophilidae has proceeded in directions that have relatively high evolvabilities

Global Reorganization of Replication Domains During Embryonic Stem Cell Differentiation

Abstract: DNA replication in mammals is regulated via the coordinate firing of clusters of replicons that duplicate megabase-sized chromosome segments at specific times during S-phase. Cytogenetic studies show that these “replicon clusters” coalesce as subchromosomal units that persist through multiple cell generations, but the molecular boundaries of such units have remained elusive. Moreover, the extent to which changes in replication timing occur during differentiation and their relationship to transcription changes has not been rigorously investigated. We have constructed high-resolution replication-timing profiles in mouse embryonic stem cells (mESCs) before and after differentiation to neural precursor cells. We demonstrate that chromosomes can be segmented into multimegabase domains of coordinate replication, which we call “replication domains,” separated by transition regions whose replication kinetics are consistent with large originless segments. The molecular boundaries of replication domains are remarkably well conserved between distantly related ESC lines and induced pluripotent stem cells. Unexpectedly, ESC differentiation was accompanied by the consolidation of smaller differentially replicating domains into larger coordinately replicated units whose replication time was more aligned to isochore GC content and the density of LINE-1 transposable elements, but not gene density. Replication-timing changes were coordinated with transcription changes for weak promoters more than strong promoters, and were accompanied by rearrangements in subnuclear position. We conclude that replication profiles are cell-type specific, and changes in these profiles reveal chromosome segments that undergo large changes in organization during differentiation. Moreover, smaller replication domains and a higher density of timing transition regions that interrupt isochore replication timing define a novel characteristic of the pluripotent state.

The sources of jet noise: experimental evidence

Abstract: The primary objective of this investigation is to determine experimentally the sources of jet mixing noise. In the present study, four different approaches are used. It is reasonable to assume that the characteristics of the noise sources are imprinted on their radiation fields. Under this assumption, it becomes possible to analyse the characteristics of the far-field sound and then infer back to the characteristics of the sources. The first approach is to make use of the spectral and directional information measured by a single microphone in the far field. A detailed analysis of a large collection of far-field noise data has been carried out. The purpose is to identify special characteristics that can be linked directly to those of the sources. The second approach is to measure the coherence of the sound field using two microphones. The autocorrelations and cross-correlations of these measurements offer not only valuable information on the spatial structure of the noise field in the radial and polar angle directions, but also on the sources inside the jet. The third approach involves measuring the correlation between turbulence fluctuations inside a jet and the radiated noise in the far field. This is the most direct and unambiguous way of identifying the sources of jet noise. In the fourth approach, a mirror microphone is used to measure the noise source distribution along the lengths of high-speed jets. Features and trends observed in noise source strength distributions are expected to shed light on the source mechanisms. It will be shown that all four types of data indicate clearly the existence of two distinct noise sources in jets. One source of noise is the fine-scale turbulence and the other source is the large turbulence structures of the jet flow. Some of the salient features of the sound field associated with the two noise sources are reported in this paper.

A Framework for the Study of Personality and Political Behaviour

Abstract: Variance in how citizens interact with the political world constitutes one of many classes of individual difference. Understanding the antecedents of this variance is the central objective for students of political behaviour, and researchers draw on numerous factors in addressing this task. Unfortunately, one potentially vital factor, personality, has received only sporadic attention in recent decades. Neglect of personality was understandable for many years, as psychological research on personality failed to produce concise taxonomies applicable to the study of politics. As the present analysis demonstrates, however, this situation has changed. Research on personality has gained new footing with the emergence of a series of five-factor models, and these frameworks hold great potential for the study of political behaviour. This thesis is advanced in a two-part analysis. First, we outline how and why our understanding of citizen politics may be improved through application of five-factor models of personality. In doing so, we focus on the components of one specific taxonomy, the Big Five lexical model. Secondly, using three datasets, we explore the link between the Big Five personality factors and a wide array of political attitudes and behaviours. Results reveal that all facets of personality captured by the Big Five framework matter for citizen politics, and that personality effects operate on virtually all aspects of political behaviour. These findings demonstrate the insight that can emerge with further application of broad-scale models of personality.

Two-band superconductivity in LaFeAsO0.89F0.11 at very high magnetic fields.

Abstract: The synthesis of the novel superconductor LaFeAsO0.89F0.11 with transition temperature Tc ∼ 26 K has been quickly followed by reports of even higher Tcs. These discoveries have generated much interest in the mechanisms and manifestations of unconventional superconductivity in the family of doped quaternary layered oxypnictides, because many features of these materials set them apart from other superconductors. Hunte et al. report very high-field resistance measurements of LaFeAsO0.89F0.11 up to 45 T, which show a remarkable enhancement of the upper critical field Bc2 as compared to values expected from the slopes dBc2/dT ≈ 2 T/K near Tc, particularly at low temperatures where the deduced Bc2(0) ≈ 63–65 T exceeds the paramagnetic limit. The recent synthesis of the superconductor LaFeAsO0.89F0.11 with transition temperature Tc ≈ 26 K (refs 1–4) has been quickly followed by reports of even higher transition temperatures in related compounds: 41 K in CeFeAsO0.84F0.16 (ref. 5), 43 K in SmFeAsO0.9F0.1 (ref. 6), and 52 K in NdFeAsO0.89F0.11 and PrFeAsO0.89F0.11 (refs 7, 8). These discoveries have generated much interest9,10 in the mechanisms and manifestations of unconventional superconductivity in the family of doped quaternary layered oxypnictides LnOTMPn (Ln: La, Pr, Ce, Sm; TM: Mn, Fe, Co, Ni; Pn: P, As), because many features of these materials set them apart from other known superconductors. Here we report resistance measurements of LaFeAsO0.89F0.11 at high magnetic fields, up to 45 T, that show a remarkable enhancement of the upper critical field Bc2 compared to values expected from the slopes dBc2/dT ≈ 2 T K-1 near Tc, particularly at low temperatures where the deduced Bc2(0) ≈ 63–65 T exceeds the paramagnetic limit. We argue that oxypnictides represent a new class of high-field superconductors with Bc2 values surpassing those of Nb3Sn, MgB2 and the Chevrel phases, and perhaps exceeding the 100 T magnetic field benchmark of the high-Tc copper oxides.

Assessment of the ways students generate arguments in science education: Current perspectives and recommendations for future directions

Abstract: Theoretical and empirical research on argument and argumentation in science education has intensified over the last two decades. The term “argument” in this review refers to the artifacts that a student or a group of students create when asked to articulate and justify claims or explanations whereas the term “argumentation” refers to the process of constructing these artifacts. The intent of this review is to provide an overview of several analytic frameworks that science educators use to assess and characterize the nature of or quality of scientific arguments in terms of three focal issues: structure, justification, and content. To highlight the foci, affordances, and constraints of these different analytic methods, the review of each framework includes an analysis of a sample argument. The review concludes with a synthesis of the three focal issues and outlines several recommendations for future work. Ultimately, this examination and synthesis of these frameworks in terms of how each conceptualizes argument structure, justification, and content is intended to provide a theoretical foundation for future research on argument in science education. © 2008 Wiley Periodicals, Inc. Sci Ed92:447–472, 2008