bluuebunny/crossref_metadata_2025 huggingface dataset:
Pragmatism and Structuralism in Occupational Therapy: The Long Conversation
Authors: Hooper Barb , Wood Wendy
Published: October 2010

The history of occupational therapy may be understood as a continual transaction between two cultural discourses: pragmatism and structuralism. Pragmatism is a way of thinking that presupposes humans are agentic by nature and knowledge is tentative and created within particular contexts. Structuralism is a way of thinking that assumes humans are composites of recurring general frameworks and that knowledge is objective and can be generalized to multiple contexts. Early in the field’s history, both pragmatist and structuralist assumptions about the human and knowledge produced different readings, or interpretations, of what constituted the appropriate tools, methods, and outcomes for occupational therapy. Consequently, occupational therapy adopted an interesting mix of pragmatist language regarding the human and structuralist approaches to knowledge, resulting in professional identity problems still experienced today. However, recent developments offer an opportunity for occupational therapists to correct old identity problems through critically evaluating incompatible assumptions and carefully reading the prevailing cultural ethos.
Interrater Reliability, Concurrent Validity, Responsiveness, and Predictive Validity of the Melville-Nelson Self-Care Assessment
Authors: Nelson David L. , Melville Lisa Link , Wilkerson Julie D. , Magness Robyne A. , Grech Jennifer L. , Rosenberg Jamie A.
Published: October 2010

OBJECTIVE. This study examines psychometric characteristics of the Melville-Nelson Self-Care Assessment (SCA), which is designed for occupational therapists working in skilled nursing facilities (SNFs) and subacute rehabilitation. Like the federally mandated Minimum Data Set, the SCA assesses seven self-care occupations in two ways: self-performance and support needed.

METHOD. Participants were SNF patients receiving subacute rehabilitation. Primary and secondary diagnoses varied widely; mean age was 76.5 years (SD = 9.8). Using the SCA, the Functional Independence Measure (FIM™), and the Klein-Bell Activities of Daily Living Scale, four teams of raters independently and simultaneously assessed 54 women and 14 men at admission and discharge; 40 participants were available for reassessment in their homes after discharge.

RESULTS. Total self-performance scores on the SCA showed (a) interrater reliability (mean ICC = .94); (b) concurrent validity with relevant areas of the FIM (rho = −.85) and the Klein-Bell (rho = −.86); (c) responsiveness in detecting change from admission to discharge, t(67) = 6.3, p < .001, with a large effect size of 1.10; and (d) moderate predictive validity of caregiving time in the home (rho = −.44) and overall function in the home as measured by the total FIM (rho = −.55) and total Klein–Bell (rho = −.54) scores. The self-performance and support measures for the seven self-care areas all had acceptable interrater reliability and concurrent validity. Eating, personal hygiene, and bathing showed little or no responsiveness to change from admission to discharge, whereas positive change was substantial in bed mobility, transfers, dressing, and toileting.

CONCLUSION. This instrument is recommended for use as part of a comprehensive occupational therapy model of practice in SNFs and subacute rehabilitation.
Powered Mobility and Preschoolers With Complex Developmental Delays
Authors: Deitz Jean , Swinth Yvonne , White Owen
Published: October 2010

OBJECTIVE. The purpose of this study was to explore the effects of a powered mobility riding toy on the participation behaviors of young children with complex developmental delays.

METHOD. A single-subject withdrawal design was used to study the effects of powered mobility on child-initiated movement occurrences, initiation of contact with others, and affect. The participants were two young children with complex developmental delays, including spastic quadriplegia. The intervention consisted of having the children use a powered mobility riding toy in their school settings during gym class and outdoor recess.

RESULTS. Primary findings were that use of the powered mobility riding toy (a) increased the number of self-initiated movement occurrences; (b) appeared to have some effect on initiation of contacts with adults and, for one child, negative adult initiations and positive peer initiations; and (c) did not have a clear impact on the amount of positive affect.

CONCLUSION. For some young children with severe motor impairments and developmental delay, use of a powered mobility device may increase self-initiated movement occurrences during free play.
Representations of Race, Ethnicity, and Social Class in Case Examples in The American Journal of Occupational Therapy
Authors: Cena Lisa , McGruder Juli , Tomlin George
Published: October 2010

OBJECTIVE. This article examines descriptors of race, ethnicity, and social class in case material in 145 articles published in The American Journal of Occupational Therapy from 1975 to 1998.

METHOD. Ethnicity labels and descriptors of occupation or other indicators of social class in case examples describing adults were collected. Frequencies of these labels and descriptors were compared with the population demographics of the 1990 U.S. census using chi-square goodness-of-fit analyses.

RESULTS. Reported indicators of race and social class were inconsistent and primarily absent in the literature, making comparisons with the U.S. population difficult. When missing race labels were assumed to be White, the case material showed disproportionate racial distributions compared with that of the U.S. population, with persons of minority races being significantly underrepresented.

CONCLUSION. The findings suggest that appropriate representation of race and social class in occupational therapy literature has not yet been achieved. The authors suggest a change in documentation conventions for occupational therapy literature and clinical writing.
Cognitive Impairment After Unilateral Hemispheric Injury of Congenital or Adult Origin
Authors: Rogers Sandra L. , Coe Christopher L. , Hartke Kara
Published: October 2010

OBJECTIVE. The purpose of this study was to assess and compare cognitive functioning in adults with unilateral hemispheric injury due to either congenital damage or an ischemic event in young adulthood.

METHOD. Adults with cerebral palsy resulting from left hemispheric brain damage were compared with adults who had a unilateral stroke in either the left or the right hemisphere. Our primary interest was to determine the impact on hemispheric dominance as revealed by dichotic listening, a task that assesses the bias for preferential listening and processing of sounds. Performance also was determined on a language-related task (word finding) and a spatial task (dot localization).

RESULTS. Scores on the Quick Neurological Screening Test indicated that all participants demonstrated significant neuromotor deficits, whereas scores on the Barthel Index indicated that the participants were functional in basic activities of daily living. On cognitive assessments, healthy control participants demonstrated a pronounced left-hemisphere dominance and right-ear advantage; participants with injury to the left hemisphere showed a strong shift toward a right-hemisphere and left-ear dominance. In particular, injury of congenital origin appeared to foster this neural reorganization and localization of language-related functions into the healthy hemisphere. This shift was associated with a deterioration of performance on both the language and the spatial tasks.

CONCLUSION. The importance of appreciating subtle deficits after unilateral injury is important in therapy. The dichotic listening test may provide a simple and useful means for evaluating persistent unilateral brain dysfunction in the clinical setting.
Factors Related to Evidence-Based Practice Among U.S. Occupational Therapy Clinicians
Authors: MacEwan Dysart Amber , Tomlin George S.
Published: October 2010

OBJECTIVE. The purpose of this study was to examine how U.S. occupational therapists access and use clinically relevant research results.

METHOD. During the spring of 2000, 209 clinically practicing occupational therapists who were members of the American Occupational Therapy Association responded to a survey (58% response rate). The distribution of opinions and self-reported behavior was portrayed by descriptive statistics, and chi-square cross-tabulations and Pearson correlation coefficients were calculated between demographic and evidence-based practice variables.

RESULTS. Respondents occasionally accessed research information through a variety of resource media. The majority (57%) implemented between one and five new, research-based treatment plans in the past year. Compared with respondents with less experience, a greater proportion of respondents with 15 or more years of clinical experience did not believe that research conclusions usually translated into treatment plans for individual clients (X2 = 20.620, p < .01). Almost three fifths (59%) of respondents reported that time was provided on the job to attend continuing education; however, 45% strongly disagreed that time was available at work to access research information. Other reported barriers to research utilization included lack of time on the job, high continuing education costs, weak research analysis skills, and placing higher value on clinical experience than on research.

CONCLUSIONS. These findings suggest that therapists are currently engaging in a modest amount of evidence-based practice. Removing the barriers identified in this study may increase research utilization among clinicians.
Multisensory Approach to Handwriting Remediation: Perceptions of School-Based Occupational Therapists
Authors: Woodward Sara , Swinth Yvonne
Published: October 2010

OBJECTIVE. The purpose of this study was to describe the current practices of school-based occupational therapists regarding their use of multisensory modalities and activities in handwriting remediation.

METHOD. A survey was sent to 313 school-based occupational therapist members of the American Occupational Therapy Association who identified themselves as working in a school system as their primary employment setting. Of these, 198 surveys were returned and analyzed descriptively, resulting in a response rate of 63.3%.

RESULTS. More than 130 different multisensory modalities and activities were documented. Twenty-five of these had previously been reported in the literature, the other 114 were documented, by respondents, within the “other” category. Most respondents reported using 5 or more modalities and activities per student, the most frequent being chalk and chalkboard. No consensus among respondents is apparent about the primary sensory systems stimulated by the modalities and activities. No difference in modality and activity use was found on the basis of demographic variables.

CONCLUSION. Overall findings indicate that the breadth of modalities and activities being used is far greater than that currently found in the literature. The results suggest a need for completing studies designed to examine the use and effectiveness of multisensory modalities and activities in handwriting remediation.
Independence as a Practice Issue in Occupational Therapy: The Safety Clause
Authors: Russell Cherry , Fitzgerald Maureen H. , Williamson Peter , Manor Debra , Whybrow Samantha
Published: October 2010

This article reports findings from interviews that explored the meanings occupational therapists attach to independence as a value and a therapeutic goal in interactions with elderly clients. Through a historical review of the literature, we trace the changing use of this term and identify two analytically distinct concepts associated with it: independence as self-reliance in activity and independence as autonomy, self-determination, or choice. We show how the latter has emerged in contemporary service contexts to represent an ideal of client-centered practice for persons with chronic disabilities, such as frail elderly clients. Using a “critical incident” interview approach with 12 Australian occupational therapists, we identified the therapists’ explicit and implicit understandings of independence as a value concept and practice issue. Our findings suggest that a mismatch often exists between idealized and practice-based talk about independence and that therapists narrativize this opposition around what we call “the safety clause.” That is, therapists invoke concerns about safety and duty of care as a caveat to implementing their independence ideals and justifying the retention of professional control. We identify key issues that therapists need to address if the rhetoric of independence-related client-centered practice is to be achieved in reality.
Therapists’ Perceptions About Making a Difference in Parent–Child Relationships in Early Intervention Occupational Therapy Services
Authors: Mayer Mary L. , White Barbara Prudhomme , Ward Judith D. , Barnaby Elizabeth M.
Published: October 2010

OBJECTIVE. The purpose of this study was to better understand occupational therapists’ experiences of making a difference in parent–child relationships.

METHOD. In this qualitative, instrumental case study, occupational therapists working in early intervention were asked to reflect on and describe occasions in which they believed that they made a real difference in parent–child relationships. The primary investigator interviewed nine experienced pediatric occupational therapists.

RESULTS. All nine therapists highly valued the parent–child relationship and focused on these relationships in therapy. Eight themes emerged that described the therapists’ practice insights and methods by which the therapists facilitated the parent–child relationship.

CONCLUSION. The occupational therapists in this study reflected insights that resonate with the literature regarding the role of the parent–child relationship in the development of children. The authors raise the question about the adequacy of instruction at the pre-service level that prepares therapists to both assess and facilitate the parent–child relationship in early intervention.
Stigma and Its Management: A Pilot Study of Parental Perceptions of the Experiences of Children With Developmental Coordination Disorder
Authors: Segal Ruth , Mandich Angela , Polatajko Helene , Cook Joanne Valiant
Published: October 2010

The findings of a small qualitative interview study with 8 parents of 6 children with developmental coordination disorder are reported. The parents discussed the social consequences of their children’s motor difficulties. The new International Classification of Functioning, Disability and Health was used as a framework for the analysis of the interview transcripts. The analysis revealed that the parents believed that their children’s impairments restrict their participation in society. The interactions between impairment and participation are interpreted in the context of stigma and its management. The significance of occupational therapy interventions in the area of physical activity play to children’s social life is discussed.
The ADL Ability and Use of Technical Aids in Persons With Late Effects of Polio
Authors: Kling Catarina , Persson Anders , Gardulf Ann
Published: October 2010

OBJECTIVE. The purpose of this study was to describe functional performance in activities of daily living (ADL) and the use of technical aids among persons with late effects of polio.

METHOD. Abilities in ADL of 150 participants 20 to 82 years of age were assessed with the Sunnaas Index of ADL, and the participants’ use of technical aids was recorded.

RESULTS. The activities in which most participants were independent were eating, daily hygiene, and communication. Many needed technical aids, adaptation of their homes, or both to perform mobility-related activities and to dress or undress, take a bath or shower, cook, or manage toilet visits. In total, 86 (57%) used mobility aids such as canes, crutches, and walkers. Thirty-one (21%) used wheelchairs within or outside the home. Bath and shower aids were the most commonly used technical aids other than mobility aids. The activity where most participants depended on others was housework.

CONCLUSION. In spite of their disabilities, most participants performed well in many ADL, functioning independently by using technical aids and by living in an adapted environment.
Improving Mobility and Community Access in an Adult With Ataxia
Authors: Gillen Glen
Published: October 2010

This case report summarizes the evaluation and treatment used to provide occupational therapy services to a man living with multiple sclerosis. Primary impairments included ataxia, paraparesis, and decreased endurance. The focus of this case study was on improving the client’s ability to use powered mobility to access the community despite severe ataxia.

A task-oriented approach was used as a frame of reference to guide the evaluation and intervention process. The primary goals of intervention were to control the degrees of freedom required for task participation and simultaneously increase postural stability, resulting in independent control of a power wheelchair. A combination of occupational therapy interventions is illustrated, including assistive technology, positioning, orthotic prescription, and adaptation of movement patterns.
Randomized Controlled Trials To Investigate Occupational Therapy Research Questions
Authors: Nelson David L. , Mathiowetz Virgil
Published: September 2010

The randomized controlled trial (RCT) has become the most widely accepted research design for testing the efficacy of health care interventions. The purposes of this paper are to (a) introduce the essential elements of RCTs, and (b) discuss some of the special problems faced by occupational therapists in conducting and interpreting RCTs. The CONSORT (Consolidated Standards of Reporting Trials) statement is recommended as an introduction to the components of RCT quality. Problems pertinent to the study of the efficacy of occupational therapy and related interventions include the importance of: theory, background, and rationale; treatment fidelity; theory-based outcomes; management of non-masked (non-blinded) interventionists and participants; and multiplicity of statistical analyses. This paper can help practitioners judge the quality of an RCT, and it can help the profession work toward the development of a cadre of qualified researchers who can adapt the well-established methods of RCTs to the study of occupation-based interventions.
Developing and Evaluating Community-Based Services Through Participatory Action Research: Two Case Examples
Authors: Taylor Renée R. , Braveman Brent , Hammel Joy
Published: September 2010

Occupational therapy has a strong history of embracing concepts of client empowerment. However there is limited literature in the field on how to achieve empowerment, or on how to extend empowerment to the level of the community and social groups and services within it. This article discusses how concepts and strategies of participatory action research, an extension of empowerment theory, can be used to inform service development and evaluation in occupational therapy. The participatory action research approach is illustrated using two case examples of participatory action research programs for persons with chronic fatigue syndrome and individuals with autoimmune deficiency syndrome (AIDS). A critical analysis of the application of this approach to research and practice is provided. Finally, the paper identifies key principles of participatory action research that can be used to guide occupational therapy services and empower both individuals and communities.
Comparing Learning of Cooking in Home and Clinic for People With Schizophrenia
Authors: Duncombe Linda W.
Published: September 2010

OBJECTIVE. The purpose of this study was to compare learning of a functional living skill in two contexts for individuals with long-term schizophrenia.

METHOD. Forty-four people with schizophrenia were matched on cognitive level. One of each pair was randomly designated to either a clinic or home cooking group, with the other assigned to the remaining group. Cooking skill was assessed using the Kitchen Task Assessment-Modified (KTA-M) both before and after the intervention. Learning for each group was analyzed using t tests. A multiple regression analysis to control for baseline differences was used to compare the learning of the two groups.

RESULTS. Participants in both groups scored significantly higher on the KTA-M after cooking lessons (t = 5.57, df = 21, p < .0001—clinic; t = 7.81. df = 21, p < .0002—home) reflecting learning of cooking skill; there was no statistically significant difference in scores on the KTA-M between the two groups based on where the learning took place (β = −1.8, df = 42, p < 0.23). Qualitative differences between the learning environments provide suggestions for teaching functional living skills to this population.

CONCLUSIONS. Learning new skills in the home was not better than learning in the clinic for people with schizophrenia in this study. Further research on the effect of context on learning for people with cognitive dysfunction and schizophrenia is recommended.
Prevalence of Parents’ Perceptions of Sensory Processing Disorders Among Kindergarten Children
Authors: Ahn Roianne R. , Miller Lucy Jane , Milberger Sharon , McIntosh Daniel N.
Published: September 2010

This study is the first to systematically examine estimated rates of sensory processing disorders using survey data. Parents of incoming kindergartners from one suburban U.S. public school district were surveyed using the Short Sensory Profile, a parent-report screening tool that evaluates parents’ perceptions of functional correlates of sensory processing disorders (McIntosh, Miller, Shyu, & Dunn, 1999a). A total of 703 completed surveys were returned, which represents 39% of the kindergarten enrollment (n = 1,796) in the district for the 1999–2000 school year. Of the 703 children represented by the surveys, 96 children (13.7% of 703) met criteria for sensory processing disorders based upon parental perceptions. A more conservative prevalence estimate of children having sensory processing disorders based on parental perceptions was calculated by assuming that all non-respondents failed to meet screening criteria. This cautious estimate suggests that based on parents’ perceptions, 5.3% (96 of 1796) of the kindergarten enrollment met screening criteria for sensory processing disorders. These percentages are consistent with hypothesized estimates published in the literature. Findings suggest a need for rigorous epidemiological studies of sensory processing disorders.
The Effect of Seated Positioning Quality on Typical 6- and 7-Year-Old Children’s Object Manipulation Skills
Authors: Smith-Zuzovsky Natalie , Exner Charlotte E.
Published: October 2010

OBJECTIVE. The purpose of this study was to examine the effect of optimal seated positioning in individually fitted furniture versus suboptimal seated positioning in standard classroom furniture on typical 6- and 7-year-old children’s object manipulation skills as measured by the In-hand Manipulation Test (IMT).

METHOD. An experimental research design was used to compare IMT performance of two groups of 20 children. One group was positioned in standard, too-large classroom furniture that did not support an optimal seated position, and one group was positioned optimally in furniture fitted to each child for tabletop activities, which allowed for hip flexion to 90°, and foot placement on the floor, and the table to be at flexed elbow height.

RESULTS. Independent groups’ t tests indicated that children who were optimally positioned performed significantly better (t = −2.77, df = 38, p < .01) than children who were tested in the too-large standard classroom furniture. The difference between groups was greater on the more difficult object manipulation items (t = −3.29, df = 38, p = .001) than on the easier items (t = −1.38, df = 38, p = .08). Age and gender may have differentially affected the results.

CONCLUSION. The study’s results suggest that the fit of furniture relative to the child’s size may have a significant impact on a young, typical child’s object manipulation skills. Complex hand skills, such as those involving in-hand manipulation with stabilization, appear to be more affected by the quality of the child’s seated position than are simpler, more well-established skills. Findings suggest that test administrators should strive to test young children in the most optimal seated position possible, particularly when the test involves complex hand skills. Further study is needed to assess the impact of the fit of furniture on hand skills in children with disabilities and on children’s performance of other tasks.
Responses of Persons With Dementia To Challenges in Daily Activities: A Synthesis of Findings From Empirical Studies
Authors: Nygård Louise
Published: October 2010

OBJECTIVES. The purpose of this study was to obtain a better understanding of strategies initiated and used in response to problems in performing daily occupations by persons with dementia in a mild to moderate stage.

METHODS. The results from seven in-depth, qualitative studies conducted by the author and coworkers describing such response strategies were analyzed and synthesized using aggregated analysis. Synthesized categories describing different types of response behavior were identified and the variations within them investigated.

RESULTS. In general, the strategies used by persons with mild to moderate dementia were intuitively employed and characterized as “common sense behavior.” The main goal of the strategies was understood as retaining a sense of control and mastery over everyday life matters. It is argued that the users implicitly or explicitly experienced a need to adapt; further exploration of how awareness of ability and disability in daily life occupation may be experienced and expressed in persons with dementia seems important.

CONCLUSION. Findings suggest that therapists and caregivers be open to detecting and supporting the response strategies used by persons with dementia as long as they appear to be useful from the perspective of the individual rather than strictly from an efficacy point of view.
Allocation of Rehabilitation Services: Who Gets a Home Evaluation
Authors: Neufeld Stewart , Lysack Cathy
Published: October 2010

OBJECTIVE. The purpose of this study was to (a) identify and describe the subpopulation of rehabilitation inpatients who receive specialized occupational therapy home evaluation services, and (b) examine these data for evidence of inequalities in access to services based on patient gender, race, age, and health insurance status.

METHOD. An archival review was conducted of all inpatient admissions (7,871) to a large urban rehabilitation hospital between January 1, 1994, and December 31, 1998. We had complete data on 7,791 of these patients of whom 6,038 were eligible to receive a home evaluation. Patient demographic data and Functional Independence Measure (FIM) data were obtained in electronic form from the hospital information system.

RESULTS. Analysis showed that 12.4% (749/6038) of eligible inpatients received an in-home evaluation, and those who did were significantly more dependent (as measured by the FIM) than those who did not (p < 0.0001). We found no evidence of inequalities in access to this specialized rehabilitation service on the basis of gender, race, age, and type of medical insurance after controlling for level of functional independence.

CONCLUSIONS. This study found no evidence of inequalities in the allocation of home evaluation services. However, it raises the larger question of how we determine whether inequalities exist. A proper assessment of inequalities in service provision requires that we know the principles by which these services should be allocated and have appropriate measures of the application of these principles. For programmatic and policy reasons, more research is needed to develop well-defined principles of resource allocation, and adequate measures of their impact so we can know whether resources and services are distributed in the way we intend.
Balassa-Samuelson and Wage, Price and Unemployment Dynamics in the Spanish Transition to EMU Membership
Authors: Juselius Katarina , Ordóñez Javier
Published: October 2010

This paper provides an empirical investigation of the wage, price and unemployment dynamics that have taken place in Spain during the last two decades. The aim of this paper is to shed light on the impact of the European economic integration on Spanish labour market and the convergence to a European level of prosperity. We found that the Balassa-Samuelson effect, product market competition, and capital liberalization have been the main driving forces in this period. The adjustment dynamics show that Spanish inflation has adjusted in the long run to the European purchasing power parity level (as measured by the German price level) corrected for the Balassa-Samuelson effect. In the medium run this long-run convergence was achieved by two types of Phillips curve mechanisms; one where the inflation/unemployment trade-off was triggered off for different levels of the interest rate and real wage costs, another one where the trade-off was a function of the real exchange rate and the interest rate. Excess wages and/or increasing cost levels in the tradable sector led to higher unemployment rather than higher prices. Thus, much of the burden of adjustment was carried by unemployment in this period.
From Refugee to Transformer: A Bourdieusian Take on a Hmong Learner's Trajectory
Authors: DE COSTA PETER I.
Published: September 2010

This ethnographic case study of a male Hmong refugee, Vue Lang, is situated against a backdrop that is characterized by a burgeoning immigrant population in the United States and a growing need to provide them with English language instruction. The Bourdieusian concepts of capital, habitus, and field (Bourdieu, 1991) are used to explicate Vue Lang's development while enrolled in a community English as a second language (ESL) project. By drawing on data sources that included videotaped classroom lessons, field notes, and written artefacts, I demonstrate how, over the course of 6 months, he developed participation, curricular, and institutional competence. The article closes with implications for both practice and research. For classroom practice, it suggests the need for teachers to (a) facilitate habitus transformation, (b) be aware that the ESL classroom is a site of cultural politics, and (c) tap the personal experiences of learners by bringing the outside in (Baynham, 2005). For policy and research, this study highlights the importance of using case studies to trace the trajectories of language learners.
Chemistry of rain events in West Africa: evidence of dust and biogenic influence in convective systems
Authors: Desboeufs K. , Journet E. , Rajot J.-L. , Chevaillier S. , Triquet S. , Formenti P. , Zakou A.
Published: October 2010

Abstract. This paper documents the chemical composition of 7 rain events associated with mesoscale convective systems sampled at the supersite of Banizoumbou, Niger, during the first special observation periods (June–July 2006) of the African Monsoon Multidisciplinary Analyses (AMMA) experiment. Time-resolved rain sampling was performed in order to discriminate the local dust scavenged at the beginning of rain event from the aerosol particles incorporated in the cloud at the end of the rain. The total elemental composition is dominated by Al, Si, Fe and Ca, indicating a high influence of dust and limited marine or anthropogenic contribution. After the aerosol wash-out, the elemental concentrations normalized to Al and the microscopic observations of diatoms, a tracer of the Bodélé depression, both indicate that the total elemental composition of rainwater is controlled by dust originating from North-eastern Saharan sources and probably incorporated in the convective cloud from the Harmattan layer. The low variability of the rain composition over the measurement period indicates a regional and temporal homogeneity of dust composition in the Harmattan layer. In the dissolved phase, the dominant anions are nitrate (NO3−), sulphate (SO42−) and chloride (Cl−). However, between June and July we observe an increasing contribution of the organic anions (formate, acetate, oxalate) associated with biogenic emissions to the total ion composition. These results confirm the large influence of biogenic emissions on the rain composition over Sahel during the wet season. The paper concludes on the capacity of mesoscale convective systems to carry simultaneously dust and biogenic compounds originating from different locations and depose them jointly. It also discusses the potential biogeochemical impact of such a phenomenon.
Aerosol flux measurements above a mixed forest at Borden, Ontario
Authors: Gordon M. , Staebler R. M. , Liggio J. , Vlasenko A. , Li S.-M. , Hayden K.
Published: October 2010

Abstract. Aerosol fluxes were measured above a mixed forest by Eddy Covariance (EC) with a Fast Mobility Particle Sizer (FMPS) at the Borden Forest Research Station in Ontario, Canada between 13 July and 12 August 2009. The FMPS, mounted at a height of 33 m (approximately 10 m above the canopy top) and housed in a temperature controlled enclosure, measured size-resolved particle concentrations for 3 to 410 nm at a rate of 1 Hz. For the size range 20
Spatial variability of POPs in European background air
Authors: Halse A. K. , Schlabach M. , Eckhardt S. , Sweetman A. , Jones K. C. , Breivik K.
Published: October 2010

Abstract. Persistent organic pollutants (POPs) are recognized for their potential to create harmful effects in remote areas and several monitoring programs have been established which measure POPs in air. Active air sampling (AAS) has so far been the recommended method used under the EMEP (co-operative programme for monitoring and evaluation of the long-range transmissions of air pollutants in Europe) measurement program. The number of EMEP AAS stations is still limited and mainly located in the north western part of Europe. Passive air sampling (PAS) methods, which have become increasingly popular in recent years, offer an opportunity as a complementary sampling strategy which could improve sampling coverage under EMEP. To gain further insight into spatial patterns of POPs in European background air and to evaluate PAS as an alternative sampling technique under EMEP, PAS were deployed at 86 European background sites during summer 2006. Duplicate PAS samplers were also deployed at EMEP AAS sites to allow for a comparison of results obtained using both methods. The PAS were analyzed for selected PCBs, HCHs, DDTs, PAHs, chlordanes and HCB, and air concentrations were calculated on the basis of losses of performance reference compounds. Air concentrations of PCBs were generally lowest in more remote areas of Northern Europe with elevated levels in more densely populated areas. γ-HCH was found at elevated levels in more central parts of Europe, whereas α-HCH, β-HCH and DDTs showed higher concentrations in the southeastern part. There was no clear spatial pattern in the concentrations for PAHs, indicative of influence by local sources, rather than long range atmospheric transport (LRAT). HCB was evenly distributed across Europe, while the concentrations of chlordanes were typically low or non-detectable. Co-deployed PAS samples showed a fair agreement between the duplicates, typically within 30%. Larger differences were seen when comparing results obtained on the basis of AAS and PAS. The latter results illustrated that coordinated PAS campaigns have the potential serve as a useful intercomparison exercise within and across existing monitoring networks. We furthermore adopted an existing Lagrangian transport model (FLEXPART) as recently modified to incorporate key processes relevant for POPs to evaluate potential source regions affecting observed PAS concentrations at selected sites. Using PCB-28 as an example, the model predicted concentrations which agreed within a factor of 3 with PAS measurements for all except 2 out of the 17 sites that were investigated in this analysis.
Ansätze zur Ordnungsreduktion von nichtlinearen Oszillatormodellen zur Anwendung im Schaltungsentwurf
Authors: Reit M. , Bremer J.-K. , Mathis W. , Stoop R.
Published: October 2010

Abstract. Im Rahmen dieser Arbeit wird ein Konzept zur Ordnungsreduktion von höherdimensionalen nichtlinearen Oszillatormodellen vorgestellt. Hierbei werden zwei wesentliche Ziele verfolgt. Zum einen wird eine höherdimensionale Modellierung der Oszillatorschaltung verwendet. Hierdurch lassen sich die Einflüsse parasitärer Effekte sowie struktureller Erweiterungen auf das dynamische Verhalten des Systems berücksichtigen. Zum anderen wird durch eine anschließende Ordnungsreduktion über die Methode der Zentrumsmannigfaltigkeit eine zweidimensionale Systembeschreibung erzeugt, deren wesentliche Dynamik derjenigen des höherdimensionalen Systems entspricht. Durch diese, in der Ordnung reduzierte, nichtlineare und parameterabhängige Systembeschreibung wird die Anwendbarkeit nichtlinearer Analysemethoden ermöglicht bzw. vereinfacht. Mit der Anwendung der Andronov-Hopf-Bifurkationsanalyse auf das reduzierte System lässt sich eine Stabilitätsuntersuchung durchführen sowie die Amplitude und Frequenz aller Zustandsgrößen approximieren. Das vorgestellte Konzept wird anhand des Beispielsystems eines LC-Tank-VCOs durchgeführt. In this paper, an order reduction technique for higher-dimensional nonlinear oscillator models, based on a center manifold approach, is presented. By modeling the oscillator circuit in the higher-dimensional state space, influences of parasitic elements and of structural extensions of the oscillator architecture on the dynamical system behavior can be examined. Using the proposed order reduction technique, a generalized second order model will be derived, which includes selected design parameters of the higher order model. By using an Andronov-Hopf bifurcation analysis, the reduced system can be studied with respect to stability as well as the amplitude and frequency of the individual state variables. The concept is applied to the design of LC-tank VCOs.
Distortion of meteor count rates due to cosmic radio noise and atmospheric particularities
Authors: Stober G. , Jacobi C. , Keuer D.
Published: October 2010

Abstract. The determination of the meteoroid flux is still a scientifically challenging task. This paper focusses on the impact of extraterrestrial noise sources as well as atmospheric phenomena on the observation of specular meteor echoes. The effect of cosmic radio noise on the meteor detection process is estimated by computing the relative difference between radio loud and radio quiet areas and comparing the monthly averaged meteor flux for fixed signal-to-noise ratios or fixed electron line density measurements. Related to the cosmic radio noise is the influence of D-layer absorption or interference with sporadic E-layers, which can lead to apparent day-to-day variation of the meteor flux of 15–20%.
Numerical modelling of nonlinear electromechanical coupling of an atomic force microscope with finite element method
Authors: Freitag J. , Mathis W.
Published: October 2010

Abstract. In this contribution, an atomic force microscope is modelled and in this context, a non-linear coupled 3-D-boundary value problem is solved numerically using the finite element method. The coupling of this system is done by using the Maxwell stress tensor. In general, an iterative weak coupling is used, where the two physical problems are solved separately. However, this method does not necessarily guarantee convergence of the nonlinear computation. Hence, this contribution shows the possibility of solving the multiphysical problem by a strong coupling, which is also referred to as monolithic approach. The electrostatic field and the mechanical displacements are calculated simultaneously by solving only one system of equation. Since the Maxwell stress tensor depends nonlinearly on the potential, the solution is solved iteratively by the Newton method.
High resolution time of arrival estimation for a cooperative sensor system
Authors: Morhart C. , Biebl E. M.
Published: October 2010

Abstract. Distance resolution of cooperative sensors is limited by the signal bandwidth. For the transmission mainly lower frequency bands are used which are more narrowband than classical radar frequencies. To compensate this resolution problem the combination of a pseudo-noise coded pulse compression system with superresolution time of arrival estimation is proposed. Coded pulsecompression allows secure and fast distance measurement in multi-user scenarios which can easily be adapted for data transmission purposes (Morhart and Biebl, 2009). Due to the lack of available signal bandwidth the measurement accuracy degrades especially in multipath scenarios. Superresolution time of arrival algorithms can improve this behaviour by estimating the channel impulse response out of a band-limited channel view. For the given test system the implementation of a MUSIC algorithm permitted a two times better distance resolution as the standard pulse compression.
MIMO-OFDM equaliser for spatial multiplexing transmission modes
Authors: Beinschob P. , Zölzer U.
Published: October 2010

Abstract. In search for faster and more reliable communication, multiple-input multiple-output (MIMO) in conjuction with Orthogonal Frequency Division Multiplexing (OFDM) are subject of extensive research. In spatial multiplexing transmission an instantaneous rise of data rates governed by the number of transmit antennas can be realised. The system performance depends highly on signal-to-interference-plus-noise ratios (SINR) at the receiver. The receiver's equaliser is supposed to maximize the SINR by mitigating the spatial interference and thus separating the transmitted signals. For this problem several solutions exist such as linear and nonlinear, per subcarrier or OFDM symbol-based. An overview of common algorithms is given and complexity is discussed. Bit error rate (BER) performance evaluations are presented. Another aspect is the impact of the equalisation strategy on the performance of bit-interleaved soft information-based channel coding schemes. As a representative, LDPC codes are chosen. Simulation results show a significant BER performance loss for symbol decision-based equalisers compared to the uncoded performance. To overcome this problem a modification of the Maximum Likelihood algorithm is proposed which yields good performance for low SNR applications.
A multifractal approach to characterize cumulative rainfall and tillage effects on soil surface micro-topography and to predict depression storage
Authors: Vidal Vázquez E. , Miranda J. G. V. , Paz-Ferreiro J.
Published: October 2010

Abstract. Most of the indices currently employed for assessing soil surface micro-topography, such as random roughness (RR), are merely descriptors of its vertical component. Recently, multifractal analysis provided a new insight for describing the spatial configuration of soil surface roughness. The main objective of this study was to test the ability of multifractal parameters to assess in field conditions the decay of initial surface roughness induced by natural rainfall under different soil tillage systems. In addition, we evaluated the potential of the joint use of multifractal indices plus RR to improve predictions of water storage in depressions of the soil surface (MDS). Field experiments were performed on an Oxisol at Campinas, São Paulo State (Brazil). Six tillage treatments, namely, disc harrow, disc plough, chisel plough, disc harrow + disc level, disc plough + disc level and chisel plough + disc level were tested. In each treatment soil surface micro-topography was measured four times, with increasing amounts of natural rainfall, using a pin meter. The sampling scheme was a square grid with 25 × 25 mm point spacing and the plot size was 1350 × 1350 mm (≈1.8 m2), so that each data set consisted of 3025 individual elevation points. Duplicated measurements were taken per treatment and date, yielding a total of 48 experimental data sets. MDS was estimated from grid elevation data with a depression-filling algorithm. Multifractal analysis was performed for experimental data sets as well as for oriented and random surface conditions obtained from the former by removing slope and slope plus tillage marks, respectively. All the investigated microplots exhibited multifractal behaviour, irrespective of surface condition, but the degree of multifractality showed wide differences between them. Multifractal parameters provided valuable information for characterizing the spatial features of soil micro-topography as they were able to discriminate data sets with similar values for the vertical component of roughness. Conversely, both, rough and smooth soil surfaces, with high and low roughness values, respectively, can display similar levels of spectral complexity. Although in most of the studied cases trend removal produces increasing homogeneity in the spatial configuration of height readings, spectral complexity of individual data sets may increase or decrease, when slope or slope plus tillage tool marks are filtered. Increased cumulative rainfall had significant effects on various parameters from the generalized dimension, Dq, and singularity spectrum, f(α). Overall, micro-topography decay by rainfall was reflected on a shift of the singularity spectra, f(α) from the left side (q>>0) to the right side (q>0) to the left side (q
Early last glacial maximum in the Southern Central Andes reveals northward shift of the westerlies at ~39 ka
Authors: Zech R. , Zech J. , Kull C. , Kubik P. W. , Veit H.
Published: October 2010

Abstract. The latitudinal position of the southern westerlies has been suggested to be a key parameter for the climate on Earth. According to the general notion, the southern westerlies were shifted equatorward during the global Last Glacial Maximum (LGM: ~24–18 ka), resulting in reduced deep ocean ventilation, accumulation of "old dissolved carbon", and low atmospheric CO2 concentrations. In order to test this notion, we applied surface exposure dating on moraines in the Southern Central Andes, where glacial mass balances are particularly sensitive to changes in precipitation, i.e. to the latitudinal position of the westerlies. Our results provide robust evidence that the maximum glaciation occurred already at ~39 ka, significantly predating the global LGM. This questions the role of the westerlies for atmospheric CO2, and it highlights our limited understanding of the forcings of atmospheric circulation.
Modeling Mediterranean ocean climate of the Last Glacial Maximum
Authors: Mikolajewicz U.
Published: October 2010

Abstract. A regional ocean general circulation model of the Mediterranean is used to study the climate of the last glacial maximum. The atmospheric forcing for these simulations has been derived from simulations with an atmospheric general circulation model, which in turn was forced with surface conditions from a coarse resolution earth system model. The model is successful in reproducing the general patterns of reconstructed sea surface temperature anomalies with the strongest cooling in summer in the northwestern Mediterranean and weak cooling in the Levantine, although the model underestimates the extent of the summer cooling in the western Mediterranean. However, there is a strong vertical gradient associated with this pattern of summer cooling, which makes the comparison with reconstructions nontrivial. The exchange with the Atlantic is decreased to roughly one half of its present value, which can be explained by the shallower Strait of Gibraltar as a consequence of lower global sea level. This reduced exchange causes a strong increase of the salinity in the Mediterranean in spite of reduced net evaporation.