bluuebunny/crossref_metadata_2025 huggingface dataset:
Stoping and the mechanisms of emplacement of the granites in the Western Ring Complex of the Galway granite batholith, western Ireland
Authors: Leake Bernard Elgey
Published: August 2011

The western end of the Galway granite batholith demonstrates the importance of stoping as a granite emplacement process, which is currently controversial, and also of space generation by uplift of the centre of a ring complex. The granite rings are shown (with a coloured 1:25 000 geological map) to be consanguineous, near coeval, and older than the 407–410 Ma late molybdenite mineralisation. A newly-recognised Mace–Ards granite, around and injected by the Aplitic Murvey-type granite of the ring core (both lacking hornblende and titanite), has biotite–muscovite–cordierite orbs and sulphide–granite orbs, showing separation of immiscible hydrous and sulphide fluids from the late magma which, with vugs, indicates a low pressure, near-roof site. The outer ring of the Errisbeg Townland granite (ETG, the main batholith granite with K-feldspar phenocrysts), was emplaced by progressive outward stoping of the country rock metagabbro, as shown by mapping, and by chemical fractionation of feldspars, biotites and bulk rocks, to the marginal, dry, fine-grained aphyric, in part garnetiferous, highly fractionated, siliceous Murvey granite. Stoping ceased when, after previously invading dense metagabbro, the outer ring complex reached the low-density Roundstone granite, which is shown for the first time to be older than the Galway batholith. This arresting of the batholith intrusion shows that stoping was such a significant process that emplacement ceased when stoping became impossible. The inside edge of the ETG grades into the slightly later, intrusive, aphyric Carna granite, which shows inward fractionation to the wet magma of the Mace–Ards granite. The ring complex core was injected by highly fractionated, dry, Aplitic Murvey-type granite, intensely hydrothermally altered by late magmatic water. The radially outward dipping, inclined igneous layering in the ETG shows that the original ETG centre was pushed upwards by the intruded Carna granite and eroded away. The Galway granite and its nearby magmatism matches the low Ba and Sr, high Th and Rb, Scottish Cairngorm Suite and similarly has few appinitic rocks associated with it. Magmatism extended over >45 Myr from ∼425 Ma to 380 Ma. It originated by slab breakoff and consequent rise of the asthenosphere, causing deep crustal melting.
Crystallographic contribution to the vital effect in biogenic carbonates Mg/Ca thermometry
Authors: Pérez-Huerta Alberto , Cusack Maggie , Dalbeck Paul
Published: August 2011

The processes involved in vital effects, defined as biological processes overriding environmental signals, are not well understood and this hampers the interpretation of environmental parameters such as seawater temperature. Insufficient knowledge is available about changes in physico-chemical parameters, in particular those related to crystallography, associated with biomineral formation and emplacement. This paper assesses the influence of crystallography on Mg2+ concentration and distribution in calcite biominerals of bivalved marine organisms, mussels and rhynchonelliform brachiopods, and considers the implications for Mg/Ca thermometry. In the mussel Mytilus edulis, changes in Mg2+ are not associated with crystallography; but in the brachiopod Terebratulina retusa, increases in Mg2+ concentrations (∼0·5–0·6 wt. ) are associated with the {0001 planes of calcite biominerals. A comparison between mussels and brachiopods with avian eggshells, which form at constant ambient temperature, also reveals that there is at least a common 0·1 wt. variation in magnesium concentration in these calcite biomineral systems unrelated to temperature or crystallography. Results demonstrate that the integration of contextual crystallographic, biological and chemical information may be important to extract accurate environmental information from biominerals.
Light guide lenses in trilobites?
Authors: Schoenemann B. , Clarkson E. N. K.
Published: August 2011

Three main types of eye have been defined in trilobites; holochroal, schizochroal and the rare abathochroal. At least in holochroal and schizochroal eyes, the lenses consist of oriented calcitic microcrystallites, the so-called trabecula, which run uninterruptedly throughout the lens from top to bottom. It is argued here that these are primary structures and not diagenetic. Holochroal eyes are commonly accepted to correspond to apposition eyes, which are the most common type of compound eyes in arthropods living today. Schizochroal eyes, present only in phacopine trilobites, are characterised by a doublet lens structure, with an aplanatic interface, correcting spherical aberration of the thick lenses to form a sharp focus for incident rays travelling parallel with the optical axis. This classic model seems to be functional for many phacopines. In these the trabecula are present, though all juxtaposed, forming a solid block. In the lenses of some phacopid species, however, the microcrystallites are separated from each other by gaps. If, during life, these gaps were filled with organic material, as the lens grew from the larval stages, or post-ecdysially, each trabeculum would be isolated from its neighbours by an organic sheath. A simple model is proposed here for the generation of the organic sheath surrounding each trabeculum. If the individual trabecula were isolated from each other, then the possibility of a new kind of visual system exists in these ‘derived’ phacopines. The differences between the refractive indexes inside and outside the trabeculum would ensure that each trabeculum acted as a light-guide, so that the whole ‘lens’ becomes a light guide bundle. This would result in a pixelled visual system, unique in the animal realm, but an archetype for modern technology of data transfer.
Research Spotlight: Three‐dimensional ash cloud observations could help aviation
Authors: Schultz Colin
Published: August 2011

In the spring of 2010 the Icelandic volcano Eyjafjallajökull erupted, sending a towering column of ash floating above the North Atlantic Ocean. The ash cloud shut down air traffic over much of Europe, significantly affecting the European economy. Although Eyjafjallajökull was one of the more recent, prominent displays of the effects of volcanic ash, similar disturbances are felt in the shadows of active volcanoes the world over. To ensure the safety of both planes and passengers, regulators rely on ash cloud dispersal models to forecast areas that might be affected by an active volcano. The models use measurements of meteorological conditions and ground‐ or satellite‐based observations of ash plumes to forecast the expected path and size of the cloud. Unfortunately, the two‐dimensional plume observations used as inputs typically lack information that could significantly improve the forecast, such as details of the volcanic cloud's vertical extent. (Journal of Geophysical Research‐Atmospheres, doi:10.1029/2009JD013162, 2010)
Research Spotlight: Low solar irradiance may not be the primary driver for the Little Ice Age
Authors: Tretkoff Ernie
Published: August 2011

Total solar irradiance (TSI), essentially a measure of the amount of light the Sun puts out, varies with the 11‐year sunspot cycle and influences Earth's climate, especially when TSI is notably higher or lower than its average values. It had been thought that TSI was especially low during a period known as the Little Ice Age, which began in the late seventeenth century and coincided with a period of unusually low sunspot activity known as the Maunder Minimum. However, Schrijver et al. now suggest that TSI during that period may not have been as low as previously thought. They analyzed direct measurements of solar magnetic activity during the recent 2008–2009 period of low sunspot activity, which they argue was similar to the activity level during the Maunder Minimum. (Geophysical Research Letters, doi:10.1029/2011GL046658, 2011)
U.K. Chief Scientific Advisor Discusses Funding, Priorities, and Communication
Authors: Tretkoff Ernie
Published: August 2011

Like other countries facing a tough economy, the government in the United Kingdom has been under pressure to make cutbacks; as budgets are becoming increasingly tighter, funding for scientific research competes with other priorities. However, in its most recent spending review, which came out last fall and sets spending levels for the next 4 years, the U.K. government provided flat funding levels for scientific research, while most government departments saw their budgets cut by 30–40%. “That was actually a major commitment by a government that was cutting everything,” Sir John Beddington, U.K. chief scientific advisor, toldEos in a one‐on‐one telephone interview in mid‐April. Beddington, who has been chief scientific advisor since 2008, shared with Eos his thoughts on priorities for science in the United Kingdom in a tough budget environment, getting expert science advice for policy making, providing scientific information following disasters, and communicating about climate change.
Floodplain Lakes: Evolution and Response
Authors: Hausmann Sonja , Hall Roland , Gell Peter
Published: August 2011

PAGES International Floodplain Lakes Workshop; Fayetteville, Arkansas, 16–19 September 2010; Human alteration of the major rivers and floodplains of the world is a global concern because they sustain aquatic ecosystems and supply food and energy to society. When in flood stage, the influence of a river extends across the floodplain and can revitalize productive wetlands. The condition of many rivers has declined worldwide, but the degree of degradation is hard to assess due to natural variability of flow and uncertainty of baseline status. Evidence of changes over decades to millennia in river and wetland conditions, however, can be quantified from physical, chemical, and biological information archived in the accumulated sediments of floodplain lakes.
AGU and European Geosciences Union Sign Memorandum of Understanding
Authors: McEntee Chris
Published: August 2011

To further our strategic goal to be a leader, collaborator, and sought after partner for scientific innovation, rigor, and interdisciplinary focus on global issues, on 5 April 2011 AGU signed a memorandum of understanding (MOU) with the European Geosciences Union (EGU). By recognizing the “mutual interests among their members” and acknowledging that “joint activities between AGU and the EGU foster international exchange in scientific research,” the agreement is intended to help further the goals and objectives of both organizations through collaboration. Central to the MOU's success is the commitment by AGU and EGU to

an exchange of information on key programs and initiatives;

an expansion of membership of both organizations through possible joint programs;

an exchange of information and possible joint activities concerning educational opportunities, student programs, and professional services; and

an exchange of information and possible co‐organization of scientific conferences.
AGU Members Press for Continued Federal Support for Basic Research on Capitol Hill
Authors: Caves Jeremy K.
Published: August 2011

While the debate over funding the federal government in 2011 is over, budget battles for 2012 and following years are now heating up. To demonstrate the importance of basic research funding, AGU collaborated with 28 other scientific and engineering societies to host 250 scientists at the sixteenth annual Science‐Engineering‐Technology Congressional Visits Day (SET‐CVD). Twenty‐four Earth and space scientists, from space physicists to hydrologists, came to Washington, D. C., on 6–7 April. Their mission was to remind lawmakers that federally supported science research drives America's economic engine; protects lives, property, and the environment; and helps keep America competitive by training the next generation of scientists, engineers, and science educators.
Research Spotlight: Determining a relevant measure of hydrologic connectivity
Authors: Schultz Colin
Published: August 2011

One of the biggest challenges in hydrology is to determine how rainwater moves through a landscape and feeds river flows. Water can circulate in underground channels, flow across the surface, or slowly permeate soil; it can either end up stored in the soil or wend its way to a stream. Representations of how water goes from one part of a landscape to another can be described by the concept of hydrologic connectivity. Unfortunately, there is no standard measure used by the research community to determine whether two wet areas are hydrologically connected. Hydrologists do not agree on how to combine soil water information and topography into a single number that would reflect a catchment's ability to rapidly transfer water from any point to a river. (Water Resources Research, doi:10.1029/2010WR009442, 2010)
Research Spotlight: Glacial dust carries iron to the Gulf of Alaska
Authors: Tretkoff Ernie
Published: August 2011

Iron is an essential nutrient for phytoplankton in the ocean, but how does iron get to the ocean? In the Gulf of Alaska the sources of iron and the processes that transport iron to the ocean are not well quantified. Crusius et al. combined satellite, meteorological, and other data to infer one source of “bioavailable” iron: dust from the Gulf of Alaska coastline. Glacial erosion causes large amounts of fine‐grained sediment, known as glacial flour, to be deposited near the coast. Some of this material can be resuspended by the wind and transported hundreds of kilometers from shore during dust storm events that occur at least annually, and most often in the fall, when river levels are low and sediments are exposed. The authors found that glacial flour dust storms are a significant source of iron to the Gulf of Alaska. They estimated the amount of iron‐containing dust transported to the Gulf of Alaska from the Copper River valley during one 2006 dust storm to be between 25 and 80 kilotons. (Geophysical Research Letters, doi:10.1029/2010GL046573, 2011)
Research Spotlight: Measuring oceanic uptake of anthropogenic carbon
Authors: Tretkoff Ernie
Published: August 2011

As anthropogenic emissions of carbon dioxide increase, contributing to global climate change, it is important to understand how much carbon the ocean absorbs.Watanabe et al. present a time series of observations of the vertical distributions of oceanic anthropogenic carbon in the North Pacific subpolar region near the Sea of Okhotsk from 1999 to 2006. The authors compared two methods of measuring the rate of oceanic uptake of anthropogenic carbon, analyzed the sources of error in each method, and determined that the two methods agreed reasonably well. Their results show that the rate of oceanic uptake of anthropogenic carbon has increased recently and, in fact, is about 1.2 times higher than expected. They attribute this difference to an increase in the strength of ocean stratification and to a recent increase in alkalinity in the Sea of Okhotsk. (Journal of Geophysical Research‐Oceans, doi:10.1029/2010JC006199, 2011)
Research Spotlight: Analyzing the ability of peat to trap gas bubbles
Authors: Tretkoff Ernie
Published: August 2011

Peatlands, thick deposits of partially decayed plant matter, are a globally important carbon store. Peat soils make up one third of the global soil carbon pool and provide one of the largest natural sources of methane to the atmosphere. Bubbles of methane, an important greenhouse gas, are produced by the decomposition of peat under waterlogged conditions. These bubbles increase in size until their buoyancy exceeds the forces keeping them in place, at which point methane bubbles move upward through the soil and are released at the surface in what is known as an ebullition event. These ebullition events are important because they may account for a large proportion of methane lost from peatlands. (Journal of Geophysical Research Biogeosciences, doi:10.1029/2010JG001478, 2011)
Guidelines for constructing climate scenarios
Authors: Mote Philip , Brekke Levi , Duffy Philip B. , Maurer Ed
Published: August 2011

Scientists and others from academia, government, and the private sector increasingly are using climate model outputs in research and decision support. For the most recent assessment report of the Intergovernmental Panel on Climate Change, 18 global modeling centers contributed outputs from hundreds of simulations, coordinated through the Coupled Model Intercomparison Project Phase 3 (CMIP3), to the archive at the Program for Climate Model Diagnostics and Intercomparison (PCMDI; http://pcmdi3.llnl.gov) [Meehl et al., 2007]. Many users of climate model outputs prefer downscaled data—i.e., data at higher spatial resolution—to direct global climate model (GCM) outputs; downscaling can be statistical [e.g., Meehl et al., 2007] or dynamical [e.g., Mearns et al., 2009]. More than 800 users have obtained downscaled CMIP3 results from one such Web site alone (see http://gdo‐dcp.ucllnl.org/downscaled cmip3_projections/, described by Meehl et al., [2007]).
Understanding feedback mechanisms of the Indo‐Pacific Ocean climate system
Authors: Meyers Gary , Cai Wenju
Published: August 2011

Indo‐Pacific Climate Variability and Change Workshop; Cairns, Queensland, Australia, 7–8 April 2011; The latest in the Australian GREENHOUSE conference series, GREENHOUSE 2011, provided scientists and representatives from industry and all levels of government the opportunity to hear about the latest in climate change science from leading researchers from Australia and around the world. This year's conference included a workshop on Indo‐Pacific climate variability and change that focused on interactions between the two ocean basins, their teleconnections, and how these might change in the future. There were 16 presentations by participants, which are now available at http://www.greenhouse2011.com/page.aspx?docid=11. Several talks at the workshop identified feedback mechanisms that control the development and structure of climate modes, using both observations and Coupled Model Intercomparison Project Phase 3 (CMIP3) results for the twentieth and 21st centuries. For example, skewness in the Indian Ocean Dipole (IOD) was associated with nonlinear temperature advection, sea surface temperature (SST)‐cloud‐radiation feedback, and feedbacks among the thermocline, SST, and wind. Observations indicated that the frequency of the IOD has increased since 1950. However, there were varying interpretations on the relative strengths of the feedbacks, how they will change in the future, and whether the increased frequency of the IOD is induced by natural variation or human activity.
Next generation atmospheric model improves hurricane forecasting
Authors: Schultz Colin
Published: August 2011

Accurately predicting hurricane development from one season to the next is a problem that crosses multiple temporal and spatial scales. The driving force behind the overall activity level for a year depends on broad climate dynamics, such as the El Niño–Southern Oscillation or the Madden‐Julian Oscillation (MJO), while the generation of an individual tropical cyclone is a product of small‐scale fluctuations in atmospheric moisture or sea surface temperature. Classically, these broad‐ or small‐scale events have fallen within the realm of climate or weather forecasting models, respectively. However, researchers have recently developed the High‐Resolution Atmospheric Model (HiRAM), which can flip between weather forecasting and climate modeling. HiRAM has 25‐kilometer horizontal resolution and can properly represent clouds, both important improvements over current models. (Geophysical Research Letters, doi:10.1029/2011GL047629, 2011)
Forecasting the Indian summer monsoon intraseasonal oscillations using genetic algorithm and neural network
Authors: Dwivedi Suneet , Pandey Avinash C.
Published: August 2011

The correct and timely forecast of the Indian summer monsoon Intraseasonal Oscillations (ISOs) is very important. It has great impact on the agriculture and economy of the Indian subcontinent region. The applicability of Genetic Algorithm (GA) is demonstrated for nonlinear curve fitting of the inherently chaotic and noisy Lorenz time series and the ISO data. A robust method is developed for the very long‐range prediction of the ISO using a feed‐forward time delay backpropagation Artificial Neural Network (ANN). Using an iterative one‐step‐ahead prediction strategy, five years (120 pentads) of advanced prediction is made for the ISO data with good forecast skill. It is shown that a hybrid GA‐ANN model may be used as an early forecast model followed by ANN only model as a more reliable model.
Examination of General Health Following Typhoon Xangsane: A Pre–Postanalysis
Authors: Conrad Kathryn A. , Amstadter Ananda B. , McCauley Jenna L. , Richardson Lisa , Kilpatrick Dean G. , Tran Trinh Luong , Trung Lam Tu , Tam Nguyen Thanh , Tuan Tran , Buoi La Thi , Ha Tran Thu , Thach Tran Duc , Acierno Ron
Published: August 2011

An individual's health status immediately following a disaster may predict long-term morbidity and mortality. However, relative to the growing literature on postdisaster mental health, less is known about physical health outcomes, particularly in developing countries. Unlike most studies, the current investigation obtained physical health data both before and after Typhoon Xangsane, which struck the Da Nang province of Vietnam in 2006, and related these predisaster data to postdisaster health functioning, among other factors. Specifically, a sample of 795 randomly selected adults was interviewed both prior to, and after the typhoon. Results indicated that participants with symptoms of major depressive disorder and panic disorder, older participants, and participants who reported high distress during the actual typhoon were most at-risk for lower self-rated health postdisaster compared to those without these risk factors. Given that Vietnam is still designated a developing country, the present study enhances the literature on postdisaster physical health correlates in developing nations.
The Cognitive Differentiation-Integration Effort Hypothesis: A Synthesis between the Fitness Indicator and Life History Models of Human Intelligence
Authors: Woodley Michael A.
Published: August 2011

This article presents a potential synthesis between the fitness indicator and life history models of human intelligence through consideration of the phenomena of ability differentiation and integration. The cognitive differentiation-integration effort hypothesis proposes that these effects result from a life history tradeoff between cognitive integration effort, a mating effort component associated with strengthening the positive manifold amongst abilities; and cognitive differentiation effort, a somatic effort component associated with the cultivation of specific abilities. This represents one of two largely independent sources of genetic variance in intelligence; the other is mediated by general fitness and mutation load and is associated with individual differences in levels of ‘genetic g‘. These two sources (along with a common source of environmental variance) combine to give rise to a variety of cognitive phenotypes characterized by different combinations of high or low levels of ‘genetic g‘ and cognitive specialism or generalism. Fundamental to this model is the assumption that measures of life history speed ( K) and g are essentially independent, which is demonstrated via meta-analysis of 10 studies reporting correlations between the variables (ρ = .023, ns, n = 2056). The implications of the model are discussed in an evolutionary, ecological, and developmental context. Seven key predictions are made in the discussion which if tested could provide definitive evidence for the hypothesis.
The Dynamic Goal Theory of Marital Satisfaction
Authors: Li Tianyuan , Fung Helene H.
Published: August 2011

Marital satisfaction is gaining increasing concern in modern society. The current review proposes the dynamic goal theory of marital satisfaction to integrate previous findings about marital satisfaction from a life span developmental perspective. The theory argues that people have multiple goals to achieve in their marriage. These marital goals can be classified into three categories: personal growth goals, companionship goals, and instrumental goals. The priority of the three types of marital goals is under dynamic changes across adulthood. Generally speaking, young couples emphasize the personal growth goals, middle-aged couples prioritize the instrumental goals, and old couples focus on the companionship goals. Whether the prioritized marital goals are achieved in marriage determines marital satisfaction. Other factors influencing marital satisfaction can be linked with marital goals in two ways. Some factors, such as life transitions and cultural values, can affect the priority of different marital goals; while other factors, such as communication pattern, problem solving, and attribution, can facilitate the achievement of the prioritized marital goals.
Effects of Length, Complexity, and Grammatical Correctness on Stuttering in Spanish-Speaking Preschool Children
Authors: Watson Jennifer B. , Byrd Courtney T. , Carlo Edna J.
Published: August 2011

Purpose

To explore the effects of utterance length, syntactic complexity, and grammatical correctness on stuttering in the spontaneous speech of young, monolingual Spanish-speaking children.

Method

Spontaneous speech samples of 11 monolingual Spanish-speaking children who stuttered, ages 35 to 70 months, were examined. Mean number of syllables, total number of clauses, utterance complexity (i.e., containing no clauses, simple clauses, or subordinate and/or conjoined clauses), and grammatical correctness (i.e., the presence or absence of morphological and syntactical errors) in stuttered and fluent utterances were compared.

Results

Findings revealed that stuttered utterances in Spanish tended to be longer and more often grammatically incorrect, and contain more clauses, including more subordinate and/or conjoined clauses. However, when controlling for the interrelatedness of syllable number and clause number and complexity, only utterance length and grammatical incorrectness were significant predictors of stuttering in the spontaneous speech of these Spanish-speaking children. Use of complex utterances did not appear to contribute to the prediction of stuttering when controlling for utterance length.

Conclusions

Results from the present study were consistent with many earlier reports of English-speaking children. Both length and grammatical factors appear to affect stuttering in Spanish-speaking children. Grammatical errors, however, served as the greatest predictor of stuttering.
Statistical, Practical, Clinical, and Personal Significance: Definitions and Applications in Speech-Language Pathology
Authors: Bothe Anne K. , Richardson Jessica D.
Published: August 2011

Purpose

To discuss constructs and methods related to assessing the magnitude and the meaning of clinical outcomes, with a focus on applications in speech-language pathology.

Method

Professionals in medicine, allied health, psychology, education, and many other fields have long been concerned with issues referred to variously as practical significance, clinical significance, social validity, patient satisfaction, treatment effectiveness, or the meaningfulness or importance of beyond-clinic or real-world treatment outcomes. Existing literature addressing these issues from multiple disciplines was reviewed and synthesized.

Conclusions

Practical significance,
an adjunct to
statistical significance,
refers to the magnitude of a change or a difference between groups. The appropriate existing term for the interpretation of treatment outcomes, or the attribution of meaning or value to treatment outcomes, is
clinical significance.
To further distinguish between important constructs, the authors suggest incorporating as definitive the existing notion that
clinical significance
may refer to measures selected or interpreted by professionals or with respect to groups of clients. The term
personal significance
is introduced to refer to goals, variables, measures, and changes that are of demonstrated value to individual clients.
Using the Preschool Language Scale, Fourth Edition to Characterize Language in Preschoolers With Autism Spectrum Disorders
Authors: Volden Joanne , Smith Isabel M. , Szatmari Peter , Bryson Susan , Fombonne Eric , Mirenda Pat , Roberts Wendy , Vaillancourt Tracy , Waddell Charlotte , Zwaigenbaum Lonnie , Georgiades Stelios , Duku Eric , Thompson Ann
Published: August 2011

Purpose

The Preschool Language Scale, Fourth Edition (PLS–4; Zimmerman, Steiner, & Pond, 2002) was used to examine syntactic and semantic language skills in preschool children with autism spectrum disorders (ASD) to determine its suitability for use with this population. We expected that PLS–4 performance would be better in more intellectually able children and that receptive skills would be relatively more impaired than expressive abilities, consistent with previous findings in the area of vocabulary.

Method

Our sample consisted of 294 newly diagnosed preschool children with ASD. Children were assessed via a battery of developmental measures, including the PLS–4.

Results

As expected, PLS–4 scores were higher in more intellectually able children with ASD, and overall, expressive communication was higher than auditory comprehension. However, this overall advantage was not stable across nonverbal developmental levels. Expressive skills were significantly better than receptive skills at the youngest developmental levels, whereas the converse applied in children with more advanced development.

Conclusions

The PLS–4 can be used to obtain a general index of early syntax and semantic skill in young children with ASD. Longitudinal data will be necessary to determine how the developmental relationship between receptive and expressive language skills unfolds in children with ASD.
An Introduction to Item Response Theory and Rasch Models for Speech-Language Pathologists
Authors: Baylor Carolyn , Hula William , Donovan Neila J. , Doyle Patrick J. , Kendall Diane , Yorkston Kathryn
Published: August 2011

Purpose

To present a primarily conceptual introduction to item response theory (IRT) and Rasch models for speech-language pathologists (SLPs).

Method

This tutorial introduces SLPs to basic concepts and terminology related to IRT as well as the most common IRT models. The article then continues with an overview of how instruments are developed using IRT and some basic principles of adaptive testing.

Conclusion

IRT is a set of statistical methods that are increasingly used for developing instruments in speech-language pathology. While IRT is not new, its application in speech-language pathology to date has been relatively limited in scope. Several new IRT-based instruments are currently emerging. IRT differs from traditional methods for test development, typically referred to as classical test theory (CTT), in several theoretical and practical ways. Administration, scoring, and interpretation of IRT instruments are different from methods used for most traditional CTT instruments. SLPs will need to understand the basic concepts of IRT instruments to use these tools in their clinical and research work. This article provides an introduction to IRT concepts drawing on examples from speech-language pathology.
Anxiety and Stuttering: Continuing to Explore a Complex Relationship
Authors: Iverach Lisa , Menzies Ross G. , O’Brian Sue , Packman Ann , Onslow Mark
Published: August 2011

Purpose

The relationship between anxiety and stuttering has been widely studied. However, a review conducted more than 10 years ago (Menzies, Onslow, & Packman, 1999) identified 5 methodological issues thought to preclude consistent research findings regarding the nature of this relationship. The purpose of the present review was to determine whether methodological improvements have occurred since the Menzies et al. (1999) review.

Method

Literature published since the Menzies et al. review was evaluated with regard to the 5 methodological issues identified in that review: (a) the construct of anxiety, (b) trait anxiety measures, (c) participant numbers, (d) treatment status of participants, and (e) speaking tasks.

Results

Despite some remaining ambiguous findings, research published since the Menzies et al. review has provided far stronger evidence of a relationship between stuttering and anxiety, and has focused more on social anxiety, expectancies of social harm, and fear of negative evaluation.

Conclusion

The aims of future research should be to improve research design, increase statistical power, employ multidimensional measures of anxiety, and further develop anxiolytic treatment options for people who stutter.
Design Challenges of AAC Apps, on Wireless Portable Devices, for Persons With Aphasia
Authors: Steele Richard , Woronoff Pamela
Published: August 2011

Successful interface design for rehabilitation technologies is much more challenging than generally thought. This paper identifies and discusses several interface methods that have proven beneficial to persons with aphasia on laptop computers that additionally show promise of successful implementation on smaller-format devices such as tablets and laptops. Illustrative, real-life examples will demonstrate how critically important it is to involve users in trying out proposed design solutions and providing user feedback.
It's Not About the Technology, or Is It? Realizing AAC Through Hard and Soft Technologies
Authors: Cook Albert M.
Published: August 2011

To many people, augmentative and alternative communication (AAC) implementation is synonymous with technologies of various types. For many others, technology is but one, sometimes small, piece of the implementation puzzle. So, is AAC about the technology or not? This paper presents a broad picture of technology as consisting of both hard and soft technologies. The article supports both types of technology as necessary for successful AAC implementation. For many individuals, hard technologies are necessary to support expressive communication. High-tech hard technologies have many options, but only a few fundamental principles, with truly unique new characteristics rarely being introduced. What does change, however, is the platform upon which the AAC devices are built. Originally, AAC devices were based on simple electronic circuits, then specialized computers, and, finally, general computers. Most recently, smart phones and pad computers have been used as the platform for AAC device functions. In this paper, I contend that it is not the technology that is critical; rather, it is our ability to take advantage of that technology for the benefit of people with complex communication needs.
Phase-field simulation of domain structures in epitaxial BiFeO3 films on vicinal substrates
Authors: Winchester B. , Wu P. , Chen L. Q.
Published: August 2011

The ferroelectric domain structures of epitaxial BiFeO3 thin films on miscut substrates were studied using a phase-field model. The effects of substrate vicinality towards (100) are considered by assuming charge-compensated surface and film/substrate interface. The predicted domain structures show remarkable agreement with existing experimental observations, including domain wall orientations and local topological domain configurations. The roles of elastic, electric, and gradient energies on the domain structures were analyzed. It is shown that the substrate strain anisotropy due to the miscut largely determines the domain variant selection and domain configurations.
The subgrid-scale scalar variance under supercritical pressure conditions
Authors: Masi Enrica , Bellan Josette
Published: August 2011

To model the subgrid-scale (SGS) scalar variance under supercritical-pressure conditions, an equation is first derived for it. This equation is considerably more complex than its equivalent for atmospheric-pressure conditions. Using a previously created direct numerical simulation (DNS) database of transitional states obtained for binary-species systems in the context of temporal mixing layers, the activity of terms in this equation is evaluated, and it is found that some of these new terms have magnitude comparable to that of governing terms in the classical equation. Most prominent among these new terms are those expressing the variation of diffusivity with thermodynamic variables and Soret terms having dissipative effects. Since models are not available for these new terms that would enable solving the SGS scalar variance equation, the adopted strategy is to directly model the SGS scalar variance. Two models are investigated for this quantity, both developed in the context of compressible flows. The first one is based on an approximate deconvolution approach and the second one is a gradient-like model which relies on a dynamic procedure using the Leonard term expansion. Both models are successful in reproducing the SGS scalar variance extracted from the filtered DNS database, and moreover, when used in the framework of a probability density function (PDF) approach in conjunction with the β-PDF, they excellently reproduce a filtered quantity which is a function of the scalar. For the dynamic model, the proportionality coefficient spans a small range of values through the layer cross-stream coordinate, boding well for the stability of large eddy simulations using this model.
A new internally contracted multi-reference configuration interaction method
Authors: Shamasundar K. R. , Knizia Gerald , Werner Hans-Joachim
Published: August 2011

We present a new internally contracted multi-reference configuration interaction (MRCI) method which, at the same time, efficiently handles large active orbital spaces, long configuration expansions, and many closed-shell orbitals in the reference function. This is achieved by treating the closed-shell orbitals explicitly, so that all required coupling coefficients and density matrices only depend on active orbital labels. As a result, closed-shell orbitals are handled as efficiently as in a closed-shell single-reference program, and this opens up the possibility to perform high-accuracy MRCI calculations for much larger molecules than before. The enormously complex equations are derived using a new domain-specific computer algebra system and semi-automatically implemented using a newly developed integrated tensor framework. The accuracy and efficiency of the MRCI method is demonstrated with applications to dioxygen-copper complexes with different ligands, some of which involve more than 30 atoms, and to spin-state splittings of ferrocene.
A refined potential for hydroxylamine clusters and the liquid phase
Authors: González-Espinoza Alfredo , Hernández-Cobos Jorge , Ortega-Blake Iván
Published: August 2011

A detailed study including ab initio calculations and classic Monte-Carlo simulations of hydroxylamine in the gas and liquid phases is presented. A classical interaction potential for hydroxylamine, which includes polarizability, many-body effects, and intramolecular relaxation, was constructed. The results of the simulation were compared to the available experimental data in order to validate the model. We conclude that liquid hydroxylamine has a multitude of hydrogen bonds leading to a large density where the existence of cis conformers and clusters of these conformers is possible. This explains the occurrence of the classical [R. Nast and I. Z. Foppl, Z. Anorg. Allg. Chem. 263, 310 (1950)10.1002/zaac.19502630511] scheme for the molecule's decomposition at room temperature and its large exothermicity and instability.
Electroluminescence and charge storage characteristics of quantum confined germanium nanocrystals
Authors: Das S. , Singha R. K. , Dhar A. , Ray S. K. , Anopchenko A. , Daldosso N. , Pavesi L.
Published: August 2011

Quantum confined Ge nanocrystals embedded in high bandgap and high-k Al2O3 dielectric matrix have been synthesized to demonstrate dual functional devices using Si-compatible fabrication technology. Transmission electron microscopy has shown the formation of Ge nanocrystals of varying diameter from 2.5 to 7.5 nm, much lower than the excitonic Bohr radius of Ge. A broad visible electroluminescence band at room temperature has been observed, which is attributed to the recombination of injected electrons and holes in Ge nanocrystals. An anti-clockwise hysteresis in the capacitance-voltage measurement of these devices indicates the charge storage in nanocrystals, useful for floating gate memory devices.
Effect of Ni/Mn concentration on exchange bias properties in bulk Ni50−xMn37+xSn13 Heusler alloys
Authors: Esakki Muthu S. , Rama Rao N. V. , Sridhara Rao D. V. , Manivel Raja M. , Devarajan U. , Arumugam S.
Published: August 2011

We report the effect of Ni/Mn variation on the exchange bias properties in the bulk Mn-rich Ni50−xMn37+xSn13 (0 ≤ x ≤ 4) Heusler alloys. The excess Mn content was found to increase the exchange bias field while it decreases the exchange bias blocking temperature (TEB) from 149 to 9 K. A maximum shift in the hysteresis loop of 377 Oe is observed for the Ni46Mn41Sn13 alloy. As compared to Mn/Sn variation, Ni/Mn variation strongly influences the exchange bias properties in Ni-Mn-Sn alloys. We observed that if the Mn content is above 37 at. % in Ni-Mn-Sn alloys, the TEB value would show a decreasing trend either by varying the Ni or Sn content.
Highly textured Sr, Nb co-doped BiFeO3 thin films grown on SrRuO3/Si substrates by rf- sputtering
Authors: Ostos C. , Raymond O. , Suarez-Almodovar N. , Bueno-Baqués D. , Mestres L. , Siqueiros J. M.
Published: August 2011

In this study, (011)-highly oriented Sr, Nb co-doped BiFeO3 (BFO) thin films were successfully grown on SrRuO3/Si substrates by rf-magnetron sputtering. The presence of parasite magnetic phases was ruled out based on the high resolution x-ray diffraction data. BFO films exhibited a columnar-like grain growth with rms surface roughness values of ≈5.3 nm and average grain sizes of ≈65–70 nm for samples with different thicknesses. Remanent polarization values (2Pr) of 54 μC cm−2 at room temperature were found for the BFO films with a ferroelectric behavior characteristic of an asymmetric device structure. Analysis of the leakage mechanisms for this structure in negative bias suggests Schottky injection and a dominant Poole-Frenkel trap-limited conduction at room temperature. Oxygen vacancies and Fe3+/Fe2+ trap centers are consistent with the surface chemical bonding states analysis from x-ray photoelectron spectroscopy data. The (011)-BFO/SrRuO3/Si film structure exhibits a strong magnetic interaction at the interface between the multiferroic film and the substrate layer where an enhanced ferromagnetic response at 5 K was observed. Zero-field cooled (ZFC) and field cooled (FC) magnetization curves of this film system revealed a possible spin glass behavior at spin freezing temperatures below 30 K depending on the BFO film thickness.
Compression-compression fatigue study on model metallic glass nanowires by molecular dynamics simulations
Authors: Shi Yunfeng , Louca Despina , Wang Gongyao , Liaw Peter K.
Published: August 2011

We report compression-compression fatigue simulations on model metallic-glass nanowires up to a 4% maximum compressive strain and 100 cycles using the molecular dynamics method. The distribution and irreversibility of the fatigue-induced deformations are characterized by the local shear strain and rise of the system temperature, respectively. Furthermore, the system potential energy, structural signatures in terms of icosahedral centers, and radial distribution functions are obtained to identify structural transformations during cyclic loading. No noticeable changes on the aforementioned isotropic structural signatures have been found during fatigue tests. Based on a binary view of the constituting local structures (stable clusters and floppy clusters) in metallic glasses, we attribute the irreversible deformation to inter-conversion of those floppy clusters, which leads to a constant composition of stable and floppy clusters. Finally, uniaxial compression tests were carried out on the cyclically loaded samples. The mechanical behaviors of fatigue-tested samples are rather similar to the original sample. Upon cyclic loading, unlike macroscopic samples, a metallic-glass nanowire is free of permanent structural damage, and therefore does not exhibit deteriorated mechanical behaviors. The excellent fatigue-resistance behavior of a metallic-glass nanowire might be related to its defect-free structure (no stress concentrators). It appears that defects may play a central role in fatigue damages in experimental metallic-glass systems.
Impact of Gd dopants on current polarization and the resulting effect on spin transfer velocity in Permalloy wires
Authors: Thomas R. L. , Zhu M. , Dennis C. L. , Misra V. , McMichael R. D.
Published: August 2011

A spin wave Doppler technique is used to measure the spin transfer velocity and the current polarization in current-carrying (Ni0.80Fe0.20)1−xGdx alloy wires. Reduced magnetization values with Gd doping suggest possible increases in the spin transfer velocity. Contrary to these expectations, we measured a decrease in the spin transfer velocity upon introducing Gd dopants. For a current density of 1011 A/m2, the measured velocities range from 6.0 m/s ± 0.6 m/s for pure Permalloy (Ni0.80Fe0.20) to 2.6 m/s ± 0.3 m/s for (Ni0.80Fe0.20)0.945Gd0.055. Interpretation of these values yields a current polarization ranging from 0.71 ± 0.02 to 0.30 ± 0.01 for the same compositions. These results reveal that Gd dopants in Permalloy have a more significant impact on the current polarization than on the material’s magnetization for these alloy compositions.
Biferroic relaxors
Authors: Kumar Ashok , Scott J. F. , Katiyar R. S.
Published: August 2011

Epitaxial biferroic relaxors of formula Pb[(Zr0.53Ti0.47)0.4(Fe0.67W0.33)0.6]O3 (PZTFW) were grown by pulsed laser deposition (PLD) techniques. Raman spectra revealed a global Fm3m symmetry with two high-frequency A1g modes that imply the existence of polar nano-regions (PNRs). Near room temperature, frequency-dependent dielectric patterns follow Vogel-Fulcher (VF) relation that implies relaxor ferroelectric phase, however, a frequency-dependent, high-temperature, Maxwell-Wagner space charge-based phase transition was also noticed. A large and irreversible magnetization with a sharp cusp in zero-field-cooled (ZFC) magnetization with low ZFC magnetic field advocates Heisenberg spin-glass behavior. Observation of slim ferroelectric hysteresis below the freezing temperature (Tf), PNRs, and spin glass confirms biferroic-relaxor nature.
Inductive determination of the optimum tunnel barrier thickness in magnetic tunneling junction stacks for spin torque memory applications
Authors: Serrano-Guisan S. , Skowronski W. , Wrona J. , Liebing N. , Czapkiewicz M. , Stobiecki T. , Reiss G. , Schumacher H. W.
Published: August 2011

We use pulsed inductive microwave magnetometry to study the precessional magnetization dynamics of the free layer in CoFeB/MgO/CoFeB based magnetic tunneling junction stacks with varying MgO barrier thickness. From the field dependence of the precession frequency we are able to derive the uniaxial anisotropy energy of the free layer and the exchange coupling between the free and the pinned layer. Furthermore the field dependence of the effective damping parameter is derived. Below a certain threshold barrier thickness we observe an increased effective damping for antiparallel orientation of free and pinned layer which would inhibit reversible low current density spin torque magnetization reversal. Such inductive measurements, in combination with wafer probe station based magneto transport experiments, allow a fast determination of the optimum tunnel barrier thickness range for spin torque memory applications in a lithography free process.