bluuebunny/crossref_metadata_2025 huggingface dataset:
The factor structure of the posttraumatic growth inventory: A comparison of five models using confirmatory factor analysis
Authors: Taku Kanako , Cann Arnie , Calhoun Lawrence G. , Tedeschi Richard G.
Published: April 2008

There are different views about the dimensions of the positive changes resulting from the struggle with traumatic events. Using Posttraumatic Growth Inventory (PTGI) data reported by participants (N = 926) experiencing a variety of traumatic events, five models of the underlying structure of the PTGI were tested via confirmatory factor analyses to examine whether the PTGI comprises three domains (Changed Perception of Self, Changed Interpersonal Relationships, and Changed Philosophy of Life), five factors (Relating to Others, New Possibilities, Personal Strength, Spiritual Change, and Appreciation of Life), or a unitary dimension. Results indicated an oblique 5‐factor model best fit the data, thus revealing the PTGI was multidimensional. Present findings offer implications for understanding the nature of posttraumatic growth.
Unpacking the relationship between posttraumatic numbing and hyperarousal in a sample of help‐seeking motor vehicle accident survivors: Replication and extension
Authors: Palyo Sarah A. , Clapp Josh D. , Beck J. Gayle , Grant DeMond M. , Marques Luana
Published: April 2008

The current study is a replication and extension of previous research that has found support for a relationship between posttraumatic numbing and hyperarousal. This study examined this association while controlling for depression in 345 motor vehicle accident survivors. Additionally, the relationships among specific hyperarousal symptoms and numbing were explored. Results provided further evidence for an association between hyperarousal and numbing, even while controlling for the influence of depression, and revealed that all hyperarousal symptoms (except hypervigilance) contribute to this association.
Treatment barriers for low‐income, urban African Americans with undiagnosed posttraumatic stress disorder
Authors: Davis Regina G. , Ressler Kerry J. , Schwartz Ann C. , Stephens Kisha James , Bradley Rebekah G.
Published: April 2008

African Americans in low‐income, urban communities are at high risk for exposure to traumatic events as well as for symptoms of posttraumatic stress disorder (PTSD). Approximately 22% of 220 participants recruited from urban hospital medical clinics met survey criteria for PTSD. Among the common traumas were having relatives/friends murdered (47%), being attacked with weapons (64% of men), and being sexually attacked (36% of women). Although desiring mental health services, only 13.3% of those with PTSD had prior trauma‐focused treatment. Barriers to treatment included limited transportation and finances, family disapproval, and unfamiliarity with accessing treatment, among others. These data highlight the need for an awareness of the high prevalence of trauma and PTSD in this population.
Mechanisms of anger and treatment outcome in combat veterans with posttraumatic stress disorder
Authors: Forbes David , Parslow Ruth , Creamer Mark , Allen Nicholas , McHugh Tony , Hopwood Mal
Published: April 2008

Research has identified anger as prominent in, and an influence on, treatment outcome for military veterans with posttraumatic stress disorder (PTSD). This study examined factors influencing the relationship between anger and outcome to improve treatment effectiveness. Participants comprised 103 veterans attending PTSD treatment. Measures of PTSD and comorbidity were obtained at intake and 9‐month follow‐up. Measures also included potential mediators of therapeutic alliance, social support, problematic/undermining relationships and fear of emotion. Path analyses supported anger as a predictor of treatment outcome, with only fear of anger and alcohol comorbidity accounting for the variance between anger and outcome. To improve treatment effectiveness, clinicians need to assess veterans' anger, aggression, and alcohol use, as well as their current fear of anger and elucidate the relationship between these factors.
Optimizing measurement of the electrical anisotropy of muscle
Authors: Chin Anne B. , Garmirian Lindsay P. , Nie Rui , Rutkove Seward B.
Published: April 2008

Skeletal muscle is electrically anisotropic, with applied high‐frequency electrical current flowing more easily along than across muscle fibers. As an early step in harnessing this characteristic for clinical use, we studied approaches for maximizing the measured anisotropy by varying electrode size and applied current frequency in the tibialis anterior of 10 normal subjects. The results were compared to those from two patients with amyotrophic lateral sclerosis (ALS). Current was applied percutaneously, first parallel and then perpendicular to the major fiber direction of the muscle at frequencies ranging from 20 kHZ to 1 MHZ, using a fixed voltage–electrode length and varying the current–electrode length. The measured anisotropy was most pronounced using the longest length current electrodes and with a 125‐kHZ applied frequency for the major outcome parameter phase. In addition, the two ALS patients showed very distinct anisotropic patterns. These results support the belief that, with the appropriate measurement technique, non‐invasive assessment of electrical anisotropy of muscle may have useful clinical application. Muscle Nerve, 2008
Bimolecular radical termination: New perspectives and insights
Authors: Johnston‐Hall Geoffrey , Monteiro Michael J.
Published: April 2008

The reversible addition‐fragmentation chain transfer‐chain length dependent termination (RAFT‐CLD‐T) method has allowed us to answer a number of fundamental questions regarding the mechanism of diffusion‐controlled bimolecular termination in free‐radical polymerization (FRP). We carried out RAFT‐mediated polymerizations of methyl acrylate (MA) in the presence of a star matrix to develop an understanding of the effect of polymer matrix architecture on the termination of linear polyMA radicals and compared this to polystyrene, polymethyl methacrylate, and polyvinyl acetate systems. It was found that the matrix architecture had little or no influence on termination in the dilute regime. However, due to the smaller hydrodynamic volumes of the stars in solution compared to linear polymer of the same molecular weight, the gel onset point occurred at greater conversions, and supported the postulate that chain overlap (or c*) is the main cause for the observed autoacceleration observed in FRP. Other theories based on “short–long” termination or free‐volume should be disregarded. Additionally, since our systems are well below the entanglement molecular weight, entanglements should also be disregarded as the cause of the gel onset. The semidilute regime occurs over a small conversion range and is difficult to quantify. However, we obtain accurate dependencies for termination in the concentrated regime, and observed that the star polymers (through the tethering of the arms) provided constriction points in the matrix that significantly slow the diffusion of linear polymeric radicals. Although, this could at first sight be postulated to be due to reptation, the dependencies showed that reptation could be considered only at very high conversions (close to the glass transition regime). In general, we find from our data that the polymer matrix is much more mobile than what is expected if reptation were to dominate. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3155–3173, 2008
Influence of ionic association on the nonisothermal crystallization kinetics of sodium sulfonate poly(butylene succinate) ionomers
Authors: Lim Jung Seop , Lee Youngil , Im Seung Soon
Published: April 2008

We evaluated the relationship between the ionic substituents and nonisothermal crystallization behavior in poly(butylene succinate) (PBS) ionomers, synthesized by the introduction of sulfonated dimethyl fumarate (SDMF) with sodium sulfonate. In addition, we investigated the effect of sodium ions on the molecular structure of the PBS backbone by solid‐state 23Na NMR analysis. Sodium ion aggregates (multiplets) was predominately created with the ionic group concentration, and melt rheology and dynamic melt analysis results showed that multiplet formation induced not only remarkable heterogeneity, but also a high degree of clustering in the PBS chains. At low ionic group concentration, well dispersed multiplets behaved as effective nuclei during the crystallization of the PBS ionomer and accelerated the rate of crystallization. As ionic group concentration grew higher, crystallization rates decreased due to hindered chain mobility by clusters consisting of numerous multiplets. A combined Ozawa and Avrami equation proved to be more effective than the Ozawa equation in describing the nonisothermal crystallization kinetics of PBS and its ionomers. The observed nucleation activity indicates that the nonisothermal crystallization rate is not directly proportional to the ionic group concentration. Superior nucleation activity was observed in PBS ionomer containing 1 mol % SDMF. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 925–937, 2008
Autonomous docking of a smart wheelchair for the Automated Transport and Retrieval System (ATRS)
Authors: Gao Chao , Miller Thomas , Spletzer John R. , Hoffman Ira , Panzarella Thomas
Published: April 2008

The Automated Transport and Retrieval System (ATRS) represents a technology‐based alternative to van conversions for automobile drivers in wheelchairs. Rather than requiring dramatic, permanent, and expensive modifications to the host vehicle, ATRS employs robotics and automation technologies and can be integrated noninvasively into a standard minivan or sport utility vehicle. At the core of ATRS is a “smart” wheelchair system that autonomously navigates between the driver's position and a powered lift at the rear of the vehicle, eliminating the need for an attendant. From an automation perspective, autonomously docking the wheelchair onto the lift platform presented the most significant technical challenge due to limited clearance between the chair wheels and the lift platform rails. To solve the docking task, we employed a light detection and ranging (LIDAR)–based approach for wheelchair localization coupled with a hybrid motion controller design. Extensive testing from the localization subsystem to the complete ATRS was conducted under representative usage conditions. This included 3 days of public demonstrations indoors at the World Congress on Disabilities, where potential end users were able to evaluate the system. In this environment, ATRS performed more than 300 consecutive cycles without failure. During 2 days of outdoor reliability testing, 97.5% docking reliability was observed. The system is scheduled to enter the commercial market in 2008. © 2008 Wiley Periodicals, Inc.
Vision‐based terrain following for an unmanned rotorcraft
Authors: Garratt Matthew A. , Chahl Javaan S.
Published: April 2008

Experiments from biology suggest that the sensing of image motion or optic flow in insects provides a means of determining the range to obstacles and terrain. When combined with a measure of ground speed from another sensor such as global positioning system, optic flow can be used to provide a measure of an aircraft's height above terrain. We apply this principle to the control of height in a helicopter, leading to the first optic flow–based terrain‐following system for an unmanned helicopter. Using feedback of the height estimated from optic flow ranging to the collective pitch control of the helicopter, it has been possible to maintain terrain clearance in flights of up to 2 km. In this paper, we present flight test data demonstrating the successful application of this to an 80‐kg Yamaha RMAX unmanned helicopter and an 8‐kg electric helicopter. To complete this work, we have extended the optic flow image interpolation algorithm (I2A) to include an adaptive capability providing a greater dynamic range. The new algorithm, called the iterative image interpolation algorithm (I2A), exhibits excellent robustness in an outdoor environment and makes it suitable for flight control in a real‐world environment. © 2008 Wiley Periodicals, Inc.
Vision‐based operations of a large industrial vehicle: Autonomous hot metal carrier
Authors: Pradalier Cédric , Tews Ashley , Roberts Jonathan
Published: April 2008

Hot metal carriers (HMCs) are large forklift‐type vehicles used to move molten metal in aluminum smelters. This paper reports on field experiments that demonstrate that HMCs can operate autonomously and in particular can use vision as a primary sensor to locate the load of aluminum. We present our complete system but focus on the vision system elements and also detail experiments demonstrating reliable operation of the materials handling task. Two key experiments are described, lasting 2 and 5 h, in which the HMC traveled 15 km in total and handled the load 80 times. © 2008 Wiley Periodicals, Inc.
Asking scientists: A decade of questions analyzed by age, gender, and country
Authors: Baram‐Tsabari Ayelet , Sethi Ricky J. , Bry Lynn , Yarden Anat
Published: April 2008

Nearly 79,000 questions sent to an Internet‐based Ask‐A‐Scientist site during the last decade were analyzed according to the surfer's age, gender, country of origin, and the year the question was sent. The sample demonstrated a surprising dominance of female contributions among K‐12 students (although this dominance did not carry over to the full sample), where offline situations are commonly characterized by males' greater interest in science. This female enthusiasm was observed in different countries, and had no correlation to the level of gender equity in those countries. This suggests that the Internet as a free‐choice science‐learning environment plays a potentially empowering and democratic role that is especially relevant to populations that are traditionally deprived of equal opportunities in learning formal science. However, worldwide, girls' interest in submitting questions to scientists dropped as they grew older relative to the boys' interest, and the stereotypically gendered science interests persisted in this environment as well. The strengths and limitations of using free‐choice Web‐based data sources for studying youth interest in science are discussed. © 2008 Wiley Periodicals, Inc. Sci Ed 93:131–160, 2009
Developmental milestones among African elephant calves on their first day of life
Authors: Bercovitch Fred B. , Andrews Jeff
Published: April 2008

A recurrent issue confronted by zoos is the extent to which animals living ex situ have life history profiles representative of those living in situ. The lengthy lifespan of African elephants hinders collecting proper comparative data, but enough information has been published to conduct preliminary analyses comparing the developmental profile of zoo and wild African elephants on their first day of life. We show that calves born in a zoo stand and walk on their own for the first time at the same age as those born in the wild. Calves born in the zoo take a little longer until first successful nursing, but the difference in age between wild and zoo is not statistically significant. Male and female calves born in zoos develop at the same pace, with data insufficient to compare with wild‐born calves. We conclude maternal parity has an effect on the age of first nursing, but not on first standing or walking, because the initiation of suckling requires coordination between two animals. We suggest that available evidence indicates that calves born in the wild and in zoos develop at comparable rates. Zoo Biol 29:120–126, 2010. © 2008 Wiley‐Liss, Inc.
Membrane translocation of glutaric acid and its derivatives
Authors: Mühlhausen C. , Burckhardt B. C. , Hagos Y. , Burckhardt G. , Keyser B. , Lukacs Z. , Ullrich K. , Braulke T.
Published: April 2008

The neurodegenerative disorder glutaric aciduria type I (GA I) is characterized by increased levels of cytotoxic metabolites such as glutaric acid (GA) and 3‐hydroxyglutaric (3OHGA). The present report summarizes recent investigations providing insights into mechanisms of intra‐ and intercellular translocation of these metabolites. Initiated by microarray analyses in a mouse model of GA I, the sodium‐dependent dicarboxylate cotransporter 3 (NaC3) was the first molecule identified to mediate the translocation of GA and 3OHGA with high and low affinity, respectively. More recently, organic anion transporters (OAT) 1 and 4 have been reported to be high‐affinity transporters for GA and 3OHGA as well as d‐2‐ and l‐2‐hydroxyglutaric acid (D2OHGA, L2OHGA). The concerted action of NaC3 and OATs may be important for the directed uptake and excretion of GA, 3OHGA, D2OHGA and L2OHGA in kidney proximal tubule cells. In addition, experimental data on cultured neuronal and glial cells isolated from mouse brain demonstrated that GA rather than 3OHGA may competitively inhibit the anaplerotic supply of tricarboxylic acid cycle intermediates from astrocytes to neurons. The identification of GA and GA derivative transporters may represent targets for new approaches to treat patients with GA I and related disorders.
Treatment of Distal Radius Fractures with Percutaneous Pinning and Pin-in-plaster
Authors: Chen Chin-En , Juhn Rei-Jahn , Ko Jih-Yang
Published: April 2008

This article describes a modified technique that combines percutaneous pinning and casting. A prospective study was conducted on 54 patients with distal radius fracture who were treated with percutaneous Kirschner wire (K-wire) fixation and pin-in-plaster technique. The surgical indications of this technique included displaced extra-articular fracture, intra-articular fracture without significant comminution, and articular step-off less than 2 mm. The average radial height was 10.96 mm, and the volar tilt was 3.97° on immediate postoperative radiographs. Upon removal of pin-in-plaster and percutaneous K-wires, the average radial height was 9.92 mm, and the volar tilt was 3.93°. Bony union was achieved in all patients; the satisfaction rate was 90.7%. Pin-in-plaster technique is effective for maintaining reduction during bone healing. The procedure provides the ability to achieve anatomic reduction and then maintains this reduction through an adequate method of immobilization.
Scaphoid Excision and Limited Wrist Fusion: A Comparison of K-Wire and Circular Plate Fixation
Authors: Rodgers Jeffrey A. , Holt Gary , Finnerty Edward P. , Miller Blake
Published: April 2008

The purpose of this study was to compare the clinical outcome, union rate, and complications of a consecutive series of Scaphoid excision and limited wrist arthrodesis performed by a single surgeon using distal radius bone graft and K-wires or circular plate fixation. A sequential series of ten patients(11 wrists) who were stabilized with temporary K-wires were compared to 11 patients (11 wrists) who were stabilized with a circular plate. Minimum follow-up was 1 year. One patient in the K-wire group was converted to a wrist fusion. Six of the remaining ten patients in the K-wire fixation group and 8 of the 11 patients in the circular plate fixation group returned for the following blinded evaluations: Quick DASH, analog pain scale, range of motion, grip and pinch strength, plain x-ray, and multi-detector computed tomography evaluation. One non-union occurred in the K-wire group. There were no non-unions in the circular plate fixation group. There was no difference in any of remaining measures or rate of complications. This study shows that equivalent results can be obtained using circular plate fixation compared to K-wires when equivalent bone graft source and fusion technique are used. If K-wire removal requires a return to the OR, circular plate fixation is more cost-effective.
The division of parent care between spouses
Authors: SZINOVACZ MAXIMILIANE E. , DAVEY ADAM
Published: April 2008

Research on the division of family work has focused on household work and child-care to the exclusion of other domains, whereas studies on care-giving for older people typically ignore spouses' support to care-givers. In this paper we apply an approach that is typical of research on spouses' division of family work in caring for parents, in that the theoretical model focuses on the ‘cultural mandates’ that guide spouses' division of care, namely gender ideologies about appropriate roles, kinship obligations, and taboos against cross-gender personal care. Other predictors of the spousal division of care drawn from economic and health-care utilisation models are also examined. The analyses use pooled data on 1,449 care occasions from the first five waves of the US Health and Retirement Study. It was found that most couples to some extent share parent care, and that the involvement of husbands depended on a complex interplay of cultural mandates and contexts. Husbands participated most in personal care for parents if the care was mandated by kinship obligations (they cared more for their own than their wife's parents), and by cross-gender care taboos (they cared more for fathers than mothers). Other cultural contexts (such as race), a spouse's other commitments, health-related ability, resources (including support from the parents' other children), and care-burden also played a role. The findings demonstrate that decisions to care for parents emerge from complex negotiations among spouses and their children and siblings or, in other words, that parental care is a family endeavour.
The ‘Healthy Passport’ intervention with older people in an English urban environment: effects of incentives and peer-group organisers in promoting healthy living
Authors: HOLLAND CAROL A. , EVERITT PAULINE , JOHNSON ANGELA , DEVI REENA
Published: April 2008

This paper reports the evaluation of the effectiveness of incentives (viz. points and prizes) and of peer-group organisers (‘older people's champions') in the outcomes of a health-improvement programme for people aged 50+ years in a multi-ethnic district of the West Midlands, England. Health promotion activities were provided, and adherence, outcome variables and barriers to adherence were assessed over six months, using a ‘passport’ format. Those aged in the fifties and of Asian origin were under represented, but people of Afro-Caribbean origin were well represented and proportionately most likely to stay in the project. Those of greater age and with more illness were most likely to drop out. There were significant improvements in exercise, diet and the uptake of influenza vaccines and eyesight tests, but slighter improvements in wellbeing. Positive outcomes related to the incentives and to liking the format. The number of reported barriers was associated with lower involvement and lack of change, as was finding activities too difficult, the level of understanding, and transport and mobility problems, but when these were controlled, age did not predict involvement. Enjoying the scheme was related to positive changes, and this was associated with support from the older people's champions.
Ethnic differences in patterns of social exchange among older adults: the role of resource context
Authors: FIORI KATHERINE L. , CONSEDINE NATHAN S. , MAGAI CAROL
Published: April 2008

Using social capital and social exchange theories, this investigation examined ethnic variation in patterns of social exchange in two heterogeneous racial groups, Blacks and Whites in the United States, and the effects of education and income on these patterns. The sample was 1,043 people aged 65–86 years from four ethnic groups (US-born European-Americans, immigrant Russians/Ukrainians, US-born African-Americans, and immigrant English-speaking Caribbeans) who had provided details of their instrumental and advice exchanges with kin and non-kin. Hierarchical multinomial logistic regressions were used to predict patterns of social exchange, variations by ethnicity, income and education, and the interactions. Ethnic differences in patterns of social exchange were found, but almost all were qualified by interactions. Those with income showed within-group heterogeneity: African-Americans and Russians/Ukrainians with higher income were more likely to engage in reciprocal instrumental kin exchange, whereas among English-speaking Caribbeans and European-Americans such exchanges were not associated with income. Unlike among European-Americans and English-speaking Caribbeans, Russians/Ukrainians with higher income and education were more likely to engage in reciprocal non-kin exchange. The findings suggest that ethnic variation in social exchange reflects both aspects of ethnic group membership and the relational context, as well as the enactment of reciprocity values in varying resource contexts.
Challenges of recruitment and retention of older people from culturally diverse communities in research
Authors: FELDMAN SUSAN , RADERMACHER HARRIET , BROWNING COLETTE , BIRD STEVE , THOMAS SHANE
Published: April 2008

The substantial and increasing number of older Australian people from culturally diverse backgrounds justifies the investigation and inclusion of their experiences in ageing research. Few empirical studies have addressed culturally diverse issues in the older population, however, in part because of the particular challenges in recruiting and retaining people from different cultural backgrounds. This article reflects on a research team's experience of recruiting participants from seven cultural groups into a study that sought to explore the links between physical activity and the built environment. Three key issues for recruiting and retaining participants from culturally diverse backgrounds were identified: having access to key local informants; the central role of paid and trained bilingual interviewers; and supporting the research partners in recruitment activities. Furthermore, it appeared that a ‘one size fits all’ approach was not appropriate and that a flexible recruitment strategy may be required to ensure successful recruitment from all cultural groups. The differences observed in this study relating to recruitment and retention rates may be more dependent on the skills and characteristics of those responsible for the recruitment and interviewing, rather than the specific cultural group itself. Older people from some cultural backgrounds may be less likely to respond to traditional recruitment methods and researchers need to be more assiduous and strategic to improve participation rates in research.
Hasidei de'ar‘a and Hasidei dekokhvaya’: Two Trends in Modern Jewish Historiography
Authors: Petrovsky-Shtern Yohanan
Published: April 2008

Gershon Hundert, one of the leading scholars of Eastern European Jewry, has portrayed Hasidism as “one of many movements of religious enthusiasm that arose in the eighteenth century.” Though most scholars today agree with this description, they diverge regarding the goals of the movement, the causes of its emergence and spread, and its impact on Eastern European Jewry. Simon Dubnow, the father-founder of modern Eastern European Jewish historiography, considered Hasidism to be a response to the seventeenth-century communal crisis. He portrayed Hasidism as a spiritual movement of ordinary Jews who rebelled against the stringencies of rabbinic Judaism and sought spiritual accommodation from charismatic yet uneducated leaders. Benzion Dinur saw Hasidism as a popular revolution against the corrupt power of the kahal, the umbrella self-governing organization of Polish Jewry. Gershom Scholem maintained that it was the popularization of Kabbalah that was responsible for the phenomenal success of Hasidism, its rapid spread, and the mass following of the zaddikim, the hasidic masters. By the end of the late twentieth century, most scholars agreed that Hasidism was a popular movement triggered by the economic breakdown of Polish Jewry, directed against the legal authorities, and led by mystically oriented leaders with no significant rabbinic pedigree or deep knowledge of traditional Jewish sources.
LA VIDA Y CARRERA DE EDUARDO MATOS MOCTEZUMA: AUTOBIOGRAFÍA
Authors: Moctezuma Eduardo Matos
Published: April 2008

Nací el 11 de diciembre de 1940 en la ciudad de México. Mi padre era de República Dominicana y tenía el cargo de Secretario de la embajada dominicana en México. Mi madre era de la ciudad de Puebla. Los primeros meses los pasé en México hasta que nombraron a mi padre en otro cargo diplomático en Panamá. De la estancia en este país tengo recuerdos vagos y muy difusos, hasta que viajamos a Venezuela en donde mi padre había sido nombrado Ministro. Allí recuerdo varias cosas, entre ellas una experiencia muy fuerte: hubo un golpe de Estado para derrocar al Presidente Medina Angarita y nuestra casa (la Embajada) fue asaltada. Tuvimos que salir huyendo con mi abuela y mis hermanos Fernanda y Rafael. Como éramos mexicanos nos alojamos en casa del Embajador de México, pues nuestra casa quedó destrozada. Se rompieron relaciones diplomáticas entre Dominicana y Venezuela y salimos rumbo a Santo Domingo, donde residimos poco más de un año, para posteriormente regresar a Panamá, en donde estudié los primeros años de primaria con los Hermanos Lasallistas en el Colegio Miramar.
INTRODUCTION
Authors: McCafferty Geoffrey G. , Fowler William R.
Published: April 2008

If we accept Good's (2001:211) definition of a textile as a “web of interlaced threads produced on a loom,” we may say that textiles have a long and storied existence in ancient Mesoamerica. In this Special Section we present four new studies on Mesoamerican textile production. All four papers are based primarily on archaeological data and analyses, but, because of the nature of the material, they cross disciplinary boundaries. At the risk of indulging in a rather hackneyed metaphor, we might envision the archaeological elements of each study as the warp embellished with a weft of ethnohistoric, ethnographic, art historical, iconographic, and epigraphic data and interpretations. In this Introduction we range across the boundaries touching first on the archaeological evidence for the antiquity of weaving and textiles in Mesoamerica, the nature of textiles as a commodity, and the theoretical foundations from political economy that influenced anthropology in the 1980s and generated a seminal article on cotton in the Aztec economy. Then we reference recent research dealing with cloth as costume that signifies ethnic and gender identity, and ideological associations with female deities. Finally, we return to the archaeology and the difficulties of preservation of textiles in Mesoamerica, setting the stage for comments on individual papers since they depend on the indirect evidence of spindle whorls and weaving implements.
Deformation by dissolution and plastic flow of a single crystal sodium chloride indenter: An experimental study under the confocal microscope
Authors: Karcz Z. , Aharonov E. , Ertas D. , Polizzotti R. , Scholz C. H.
Published: April 2008

A halite cone‐shaped indenter loaded against a flat silicate surface and immersed in saturated solution deforms in two distinct stages. The first stage is characterized by slow convergence rates and rapid contact area reduction, while the second stage is characterized by high convergence rates and fluctuations around a constant contact area. This sequence shows a progression of the system from a far from equilibrium state, through an overshoot point to a dynamic steady state. We propose that the evolution of the system is dictated by an interaction between two deformation mechanisms. The first is undercutting dissolution that reduces the area of the contact, and the second is probably plastic flow that increases it. Undercutting dissolution is driven by a horizontal thermal gradient and gradients in strain and surface energy. The feedback between these two mechanisms is responsible for the establishment of a steady state at the latter part of the second deformation stage, and is at the core of the free face pressure solution model. On the basis of this data we model the relation between undercutting rates at grain contacts and rates of granular compaction.
On ionospheric trough conductance and subauroral polarization streams: Simulation results
Authors: Zheng Yihua , Brandt Pontus C. , Lui Anthony T. Y. , Fok Mei‐Ching
Published: April 2008

Subauroral polarization streams (SAPS) are usually associated with geomagnetically disturbed times and considered a manifestation of magnetosphere and ionosphere coupling. Previous research results using radar and satellite measurements have revealed many features of the SAPS events. In this paper we focus on the effects of subauroral trough conductance on the attributes of SAPS and the evolution of the coupled magnetosphere and ionosphere system through the comprehensive ring current model, which includes the coupled electrodynamics of the inner magnetosphere and ionosphere with a self‐consistent description of the electric field. Our numerical analysis indicates that low conductance at the subauroral latitudes (due to midlatitude trough) is critical to the large amplitude of SAPS. The model results are generally in good agreement with common characteristics of SAPS and are consistent with their existing generation mechanism.
MARSIS subsurface radar investigations of the South Polar reentrant Chasma Australe
Authors: Farrell W. M. , Clifford S. M. , Milkovich S. M. , Plaut J. J. , Leuschen C. J. , Picardi G. , Gurnett D. A. , Watters T. R. , Safaeinili A. , Ivanov A. B. , Phillips R. J. , Stofan E. R. , Heggy E. , Cummer S. A. , Espley J. R.
Published: April 2008

The Mars Express/Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) has conducted the first‐ever subsurface probing of the south polar layered deposits (SPLD) revealing internal structure that is rich in detail. We report on subsurface features detected from a set of orbits that passed over the largest of the south polar reentrants, Chasma Australe, at the edge of the SPLD. We present selected MARSIS overflights to both document the unique observations and gain insight into the possible origin of this feature. We conclude that MARSIS observations clearly reveal new evidence of subsurface structure, such as (1) internal bands, (2) the continuation of the Prometheus basin floor beneath the SPLD to form a prominent basal interface, and (3) the presence of a possible ice‐rich layer on the Prometheus basin floor extending to 500‐m depth. There is no obvious indication of a present‐day aquifer at the head of the chasma and identification of features associated with a past aquifer and water flow is ambiguous. While MARSIS observations may not uniquely solve the chasma origin debate, they do reveal the subsurface region beneath this very interesting feature for the first time.
An investigation into the mechanisms controlling seasonal speedup events at a High Arctic glacier
Authors: Bingham Robert G. , Hubbard Alun L. , Nienow Peter W. , Sharp Martin J.
Published: April 2008

Seasonal variations in ice motion have been observed at several polythermal ice masses across the High Arctic, including the Greenland Ice Sheet. However, such variations in ice motion and their possible driving mechanisms are rarely incorporated in models of the response of High Arctic ice masses to predicted climate warming. Here we use a three‐dimensional finite difference flow model, constrained by field data, to investigate seasonal variations in the distribution of basal sliding at polythermal John Evans Glacier, Ellesmere Island, Canada. Our results suggest that speedups observed at the surface during the melt season result directly from changes in rates of basal motion. They also suggest that stress gradient coupling is ineffective at transmitting basal motion anomalies to the upper part of the glacier, in contrast to findings from an earlier flow line study at the same glacier. We suggest that stress gradient coupling is limited through the effect of high drag imposed by a partially frozen bed and friction induced by valley walls and significant topographic pinning points. Our findings imply that stress gradient coupling may play a limited role in transmitting supraglacially forced basal motion anomalies through Arctic valley and outlet glaciers with complex topographic settings and highlight the importance of dynamically incorporating basal motion into models predicting the response of the Arctic's land ice to climate change.
Topographic controls on snow distribution, soil moisture, and species diversity of herbaceous alpine vegetation, Niwot Ridge, Colorado
Authors: Litaor M. I. , Williams M. , Seastedt T. R.
Published: April 2008

The nature of the snowpack has the potential to strongly influence the patterns of alpine plant productivity and composition by governing soil moisture levels, growing season duration and the thermal regime of alpine soils. This study evaluates these relationships by modeling the interrelationships of snow depth, snow water equivalent (SWE), snow disappearance rate, soil moisture, attributes of the alpine plant community and selected terrain factors using decision‐tree techniques at Niwot Ridge, Colorado Front Range. The modeling results showed a strong correlation (r2 > 0.9, P < 0.001) between the snow disappearance rate and SWE and terrain factors that control the degree of shelter and exposure of a given local and elevation. The model was sufficiently robust to predict the spatial distribution of the snowpack for 12 years that exhibited average snow fall (r2 = 0.8, P < 0.001), but yielded lower correlation (r2 = 0.2, P < 0.001) in drought years. Soil moisture was significantly correlated (r2 = 0.7, P < 0.001) with snow‐fall amounts and terrain factors; however, meltwater and summer rain offset the potential soil moisture deficit in windward sites. Annual plant biomass did not correlate well with snow attributes and soil moisture because the cascading impact of topography on snowpack and soil moisture was not well captured by measurements of aboveground biomass. In contrast, the species richness index was significantly correlated with snow depth and soil moisture (r2 = 0.7, P < 0.001), thereby demonstrating the importance of snow on some attributes of the alpine plant community.
Potential for issuing ionospheric warnings to Canadian users of marine DGPS
Authors: Skone S. , Coster A.
Published: April 2008

Under normal operating conditions marine DGPS horizontal positioning accuracies on the order of several meters are achieved in North America. Degradations in positioning accuracy can occur during enhanced ionospheric activity. An ionospheric phenomenon known as storm enhanced density (SED) is observed to develop in the middle to high latitudes during ionospheric storm events. Very large gradients in total electron content are observed in the vicinity of this feature with DGPS positioning errors increased by a factor of 10–30 versus quiet conditions. The specific evolution of a given SED event and the magnitude of expected impact are not generally predictable. A method to monitor development of SED is to compute ionospheric maps in real time. Local gradients can then be computed for various geographic regions from North American maps of ionospheric delay. Sources of real‐time ionospheric information include the Wide Area Augmentation System (WAAS) and the Canadian GPS•C service. These are wide area differential GPS systems. In this paper, a real‐time ionospheric warning system is investigated for North American (primarily Canadian) DGPS users based on available real‐time data. The WAAS and GPS•C ionospheric models are inadequate to resolve ionospheric gradients for 100–200 km scale sizes. Raw GPS data from GPS•C reference sites can be used, however, to observe large ionospheric gradients and interpret the expected impact on DGPS users. Potential exists to issue marine user warnings based on this method. Results of this work can readily be extended to land DGPS applications, such as the NDGPS service in the United States.
Devonian geodynamic evolution of the Variscan Belt, insights from the French Massif Central and Massif Armoricain
Authors: Faure Michel , Bé Mézème Eugène , Cocherie Alain , Rossi Philippe , Chemenda Alexandre , Boutelier David
Published: April 2008

The Paleozoic French Variscan Belt in Massif Central and Massif Armoricain is a collision belt that provides a good example of a suture zone where ophiolites are rare, and the frontal (i.e., the magmatic arc) part of the upper plate is not present. In the lower plate (or Gondwana), the continental rocks are subdivided into an Upper Gneiss Unit (UGU) and a Lower Gneiss Unit (LGU). The UGU experienced a high‐pressure (and likely ultra‐high‐pressure) metamorphism followed by crustal melting during their exhumation. New chemical U‐Th‐Pb monazite ages and ion‐probe U‐Pb zircon ages on migmatites allow us to constrain the P‐T‐t paths followed by the UGU and LGU. By comparison with thermomechanical experiments, a possible geodynamic evolution scenario can be proposed for the Variscan convergence. The high‐compression regime of continental subduction developed during the initial subduction of the northern margin of Gondwana under Armorica in Silurian times. This induced the formation of a new subduction zone in the back‐arc basin, which is the youngest, hottest, and thus mechanically the weakest part of the overriding plate. As a result, the arc‐back‐arc basin domain has been almost totally subducted below Armorica. Only a limited part of the back‐arc basin rocks remains exposed in the Devonian St‐Georges‐sur‐Loire Unit. Subsequently, the continental subduction of Gondwana resumed with a steeper dip associated with low‐compression regime that in turn allowed the high‐pressure rocks to be exhumed and partly melted in Late Devonian times. Such a scheme depicts quite well the complexity of the Variscan Belt.
Efficient prediction uncertainty approximation in the calibration of environmental simulation models
Authors: Tolson Bryan A. , Shoemaker Christine A.
Published: April 2008

This paper is aimed at improving the efficiency of model uncertainty analyses that are conditioned on measured calibration data. Specifically, the focus is on developing an alternative methodology to the generalized likelihood uncertainty estimation (GLUE) technique when pseudolikelihood functions are utilized instead of a traditional statistical likelihood function. We demonstrate for multiple calibration case studies that the most common sampling approach utilized in GLUE applications, uniform random sampling, is much too inefficient and can generate misleading estimates of prediction uncertainty. We present how the new dynamically dimensioned search (DDS) optimization algorithm can be used to independently identify multiple acceptable or behavioral model parameter sets in two ways. DDS could replace random sampling in typical applications of GLUE. More importantly, we present a new, practical, and efficient uncertainty analysis methodology called DDS–approximation of uncertainty (DDS‐AU) that quantifies prediction uncertainty using prediction bounds rather than prediction limits. Results for 13, 14, 26, and 30 parameter calibration problems show that DDS‐AU can be hundreds or thousands of times more efficient at finding behavioral parameter sets than GLUE with random sampling. Results for one example show that for the same limited computational effort, DDS‐AU prediction bounds can simultaneously be smaller and contain more of the measured data in comparison to GLUE prediction bounds. We also argue and then demonstrate that within the GLUE framework, when behavioral parameter sets are not sampled frequently enough, Latin hypercube sampling does not offer any improvements over simple random sampling.
Influence of cohesion on the incipient motion condition of sediment mixtures
Authors: Kothyari Umesh C. , Jain Rajesh Kumar
Published: April 2008

Previous investigations on initiation of motion and erosion of cohesive sediment mixtures have not included gravel within the mixtures. Experimental results on the incipient motion characteristics of cohesive sediment mixtures containing gravel are presented in this paper. The sediment used consisted of fine gravel mixed with clay in proportions varying from 10% to 50% by weight, and fine gravel with fine sand mixed in equal proportion, with clay proportions again varying from 10% to 50% by weight. The stages of the incipient condition of motion were visually identified. Three modes of initiation of motion of cohesive sediment mixtures were noticed, namely, pothole erosion, line erosion, and mass erosion. The modes of initiation of motion changed mainly with clay percentages in the mixture, its antecedent moisture characteristics, and the applied shear stress. Analysis of the experimental data from the present study and the literature revealed that depending upon the flow and sediment characteristics, the critical shear stress of the incipient motion condition in cohesive sediment mixtures can be up to 50 times larger than the critical shear stress of cohesionless sediments having similar arithmetic mean size as the cohesive sediments. On the basis of dimensional considerations, a relationship is proposed for the determination of critical shear stress of the incipient motion condition in cohesive sediment mixtures also containing gravel. The variables, namely, clay percentage, void ratio, and unconfined compressive strength of the sediment bed, are noticed to be the main parameters controlling the incipient motion condition of the cohesive sediments. In the absence of cohesion, the proposed relationship reduces to the critical shear stress for the incipient motion condition of the cohesionless sediment mixture having the same arithmetic mean size. The condition for the threshold of erosion of cohesive sediment mixtures by the flow is thus parameterized in the present study.
Optimal design and experimental verification of a magnetically actuated optical image stabilization system for cameras in mobile phones
Authors: Chiu Chi-Wei , Chao Paul C.-P. , Kao Nicholas Y.-Y. , Young Fu-Kuan
Published: April 2008

A novel miniaturized optical image stabilizer (OIS) is proposed, which is installed inside the limited inner space of a mobile phone. The relation between the VCM electromagnetic force inside the OIS and the applied voltage is first established via an equivalent circuit and further validated by a finite element model. Various dimensions of the VCMs are optimized by a genetic algorithm (GA) to maximize sensitivities and also achieving high uniformity of the magnetic flux intensity.
Multiparticle collision dynamics modeling of viscoelastic fluids
Authors: Tao Yu-Guo , Götze Ingo O. , Gompper Gerhard
Published: April 2008

In order to investigate the rheological properties of viscoelastic fluids by mesoscopic hydrodynamics methods, we develop a multiparticle collision (MPC) dynamics model for a fluid of harmonic dumbbells. The algorithm consists of alternating streaming and collision steps. The advantage of the harmonic interactions is that the integration of the equations of motion in the streaming step can be performed analytically. Therefore, the algorithm is computationally as efficient as the original MPC algorithm for Newtonian fluids. The collision step is the same as in the original MPC method. All particles are confined between two solid walls moving oppositely, so that both steady and oscillatory shear flows can be investigated. Attractive wall potentials are applied to obtain a nearly uniform density everywhere in the simulation box. We find that both in steady and oscillatory shear flows, a boundary layer develops near the wall, with a higher velocity gradient than in the bulk. The thickness of this layer is proportional to the average dumbbell size. We determine the zero-shear viscosities as a function of the spring constant of the dumbbells and the mean free path. For very high shear rates, a very weak “shear thickening” behavior is observed. Moreover, storage and loss moduli are calculated in oscillatory shear, which show that the viscoelastic properties at low and moderate frequencies are consistent with a Maxwell fluid behavior. We compare our results with a kinetic theory of dumbbells in solution, and generally find good agreement.