bluuebunny/crossref_metadata_2025 huggingface dataset:
Free Vibration Analysis and Optimal Design of a Clamped-free Single Lap Joint with Unidirectional Laminated Narrow Plates
Authors: Apalak M. Kemal , Yildirim Mustafa
Published: March 2009

In this study the three-dimensional free vibration analysis and modal stress analysis of an adhesively bonded composite single lap joint having unidirectional laminated narrow plates and subjected to clamped-free condition are carried out. The first ten natural frequencies and mode shapes of the adhesive joint are considered. The effects of fiber angle, fiber volume fraction, overlap length, and plate thickness on the natural frequencies and the mode shapes of the adhesive joint are investigated using the back-propagation artificial neural network (ANN) method. A series of free vibration and stress analyses is carried out using the finite element method for random values of the fiber angle, the fiber volume fraction, the overlap length, and the plate thickness so that the proposed ANN model can be trained successfully to predict the first ten natural frequencies as well as the corresponding modal strain energies. The ANN models indicate that the fiber angle is a more dominant parameter than the fiber volume fraction on the natural frequencies and the corresponding mode shapes of the adhesive joint, and the plate thickness and the overlap length are important geometrical design parameters whereas the adhesive thickness has a minor effect. In addition, genetic algorithm is combined with the present ANN model to achieve the optimal joint design which satisfies maximum natural frequency and minimum modal strain energy conditions for each natural frequency and mode shape of the adhesively bonded composite single lap joint.
Changing schools: more than a lick of paint and a well-orchestrated performance?
Authors: Thomson Pat , McGregor Jane , Sanders Ethel , Alexiadou Nafsika
Published: March 2009

Creative Partnerships aims to change the ways in which children learn and teachers teach, and to support whole school change. Our research examines how schools take up the `cultural offer' made by Creative Partnerships. In this article, drawing on data from snapshot visits to 40 English schools, we suggest that it has made a difference to school culture and to its meaning-making practices. In many of the schools it has also spread beyond one-off projects to help teachers change their pedagogical approach more generally. We found a consistent trend across the schools towards cross-curricular and integrated approaches which in some cases had also produced structural shifts in the use of space, time, budgets and promotion positions. We raise some concerns about the ways in which performative regimes inhibit what some schools are able to achieve, but also point to challenges for Creative Partnerships relating to assessment, knowledge, and understandings about social justice.
Improving the English urban primary school: questions of policy
Authors: Maguire Meg , Pratt-Adams Simon
Published: March 2009

This article argues that the focus within much normative education policy is with in-school effects which has sidelined the impact of structural and material factors in respect of the urban primary school. Educational reforms intended to improve schools are less likely to make much impact unless these contextualizing matters are directly addressed. First, the article briefly outlines its approach towards policy in general terms; then it looks at what is meant by urbanization and the urban primary school. Some of the historical continuities that still influence the urban primary school are identified. The article then turns to two forms of contemporary public policy that address the urban primary school indirectly and directly; these are housing mix and the Intensifying Support and Improving Schools Programmes (ISP). One objective is to demonstrate the persistence of inequalities in schooling. The second objective is to highlight the complexities and contradictions that characterize attempts to improve the urban primary school.
Border crossings
Authors: MacBeath John
Published: March 2009

This article comments on international consequences of performativity cultures and curriculum standardization, focusing particularly on the situation in England. It highlights the divide between youth culture and school learning, and the particular damage for poorer students. It argues the impact of the English performativity regime on teacher morale and learner engagement, the negative effects of `workforce remodelling' and the problems arising from incoherent inclusion policies. Despite the problems caused by the policy regime, the article ends by highlighting innovative schools which have been courageous enough to swim against the tide.
Danish Bell Beaker pottery and flint daggers – the display of social identities?
Authors: Sarauw Torben
Published: March 2009

This article summarizes and discusses recent research into the Danish Bell Beaker phenomenonc.2350–1950 BC. Its focus is on the meaning of material culture here represented by Bell Beakers and bifacial lanceolate flint daggers, both seen from a social perspective. The Bell Beaker pottery is known to have had a very wide distribution. However, questions remain as to why Bell Beakers were only adopted in some regions and what meaning this special pottery had? Similarly the Danish type I daggers, which were manufactured within the context of the Danish Bell Beaker phenomenon in the northern parts of Jutland, had a wide distribution. Daggers of this type, which in general denote male identity, were exported in vast quantities, especially to Norway and the western parts of Sweden. In both case studies the evidence from a Danish Bell Beaker settlement site excavated in recent years – Bejsebakken – plays a major part.
An Evidence-Based Approach to Hamstring Strain Injury: A Systematic Review of the Literature
Authors: Prior Mathew , Guerin Michelle , Grimmer Karen
Published: March 2009

Background:

Hamstring strain injury is a common problem within sport. Despite research interest, knowledge of risks for and management of hamstring strain is limited, as evidenced by high injury rates.

Objective:

To present the current best evidence for hamstring strain injury risk factors and the management of hamstring strain injury.

Methods:

MEDLINE, AMED, SportDiscus, and AUSPORT databases were searched (key terms “hamstring” and “strain,” “injury,” “pull,” or “tear”) to identify relevant literature published between 1982 and 2007 in the English language. Studies of adult athlete populations (older than 18 years) pertaining to hamstring strain incidence, prevalence, and/or intervening management of hamstring strain injury were included. Articles were limited to full-text randomized, controlled studies or cohort studies. Twenty-four articles were included. Articles were critically appraised using the McMaster Quantitative Review Guidelines instrument. Data pertaining to injury rates and return to sport outcomes were extracted. Each author undertook independent appraisal of a random selection of articles after establishing inter-rater agreement of appraisal.

Results:

Previous strain, older age, and ethnicity were consistently reported as significant risks for injury, as was competing in higher levels of competition. Associations with strength and flexibility were conflicting. Functional rehabilitation interventions had preventive effects and resulted in significantly earlier return to sport. Additionally, weak evidence existed for other interventions.

Conclusion:

Current evidence is inconclusive regarding most interventions for hamstring strain injury, while the effect of potentially modifiable risks is unclear. Further high-quality prospective studies into potential risks and management are required to provide a better framework within which to target interventions.
Sagittal Plane Knee Biomechanics and Vertical Ground Reaction Forces Are Modified Following ACL Injury Prevention Programs: A Systematic Review
Authors: Padua Darin A. , DiStefano Lindsay J.
Published: March 2009

Context:

Injuries to the anterior cruciate ligament (ACL) occur because of excessive loading on the knee. ACL injury prevention programs can influence sagittal plane ACL loading factors and vertical ground reaction force (VGRF).

Objective:

To determine the influence of ACL injury prevention programs on sagittal plane knee biomechanics (anterior tibial shear force, knee flexion angle/moments) and VGRF.

Data Sources:

The PubMed database was searched for studies published between January 1988 and June 2008. Reference lists of selected articles were also reviewed.

Study Selection:

Studies were included that evaluated healthy participants for knee flexion angle, sagittal plane knee kinetics, or VGRF after performing a multisession training program. Two individuals reviewed all articles and determined which articles met the selection criteria. Approximately 4% of the articles fulfilled the selection criteria.

Data Extraction:

Data were extracted regarding each program’s duration, frequency, exercise type, population, supervision, and testing procedures. Means and variability measures were recorded to calculate effect sizes. One reviewer extracted all data and assessed study quality using PEDro (Physiotherapy Evidence Database). A second reviewer (blinded) verified all information.

Results:

There is moderate evidence to indicate that knee flexion angle, external knee flexion moment, and VGRF can be successfully modified by an ACL injury prevention program. Programs utilizing multiple exercises (ie, integrated training) appear to produce the most improvement, in comparison to that of single-exercise programs. Knee flexion angle was improved following integrated training (combined balance and strength exercises or combined plyometric and strength exercises). Similarly, external knee flexion moment was improved following integrated training consisting of balance, plyometric, and strength exercises. VGRF was improved when incorporating supervision with instruction and feedback on proper technique.

Conclusion:

ACL injury prevention programs that are aimed at modifying sagittal plane knee biomechanics and VGRF should use an integrated training approach that incorporates instruction and feedback on proper movement technique.
Focused Extracorporeal Shock Wave Therapy in Calcifying Tendinitis of the Shoulder: A Meta-Analysis
Authors: Vavken Patrick , Holinka Johannes , Rompe Jan Dirk , Dorotka Ronald
Published: March 2009

Background:

The objective of this study is to assess the effectiveness of extracorporeal shock wave therapy in the management of calcifying tendinitis of the shoulder. Furthermore, a dose-response relationship was sought as a secondary confirmation of effectiveness.

Hypothesis:

Focused extracorporeal shock wave therapy has a high, dose-responsive effectiveness in the management of calcifying tendinitis of the shoulder.

Study Design:

Meta-analysis.

Methods:

Studies were identified from online databases (MEDLINE, EMBASE, and Cochrane Controlled Trials Register), manual searches, and personal communication with experts in the field. After assessment of heterogeneity, a random effects model was generated. The primary end points were identified as pain and function by using the visual analog scale and the Constant-Murley Score, respectively. These end points were pooled and the weighted mean differences and 95% confidence intervals were estimated. Odds ratios of the secondary end point deposit resorption were pooled.

Results:

In 14 studies, shock wave therapy led to a significantly higher reduction of pain (weighted mean difference, –2.8 points; 95% confidence interval, –4.2 to –1.5 points) and improvement of function (weighted mean difference, 19.8 points; 95% confidence interval, 13.4–26.3 points), compared to other treatments and placebo. High-energy treatment produced significantly better results than low-energy treatment for pain reduction (weighted mean difference, 1.7 points; 95% confidence interval, 0.7–2.6 points) and improvement of function (weighted mean difference, 10.7 points; 95% confidence interval, 7.2–14.1 points). These results are consistent with a dose-response relationship supporting the effectiveness of shock wave therapy.

Conclusion:

Shock wave therapy for calcifying tendinitis of the shoulder is effective in pain relief, function restoration, and deposit resorption; however, these conclusions are susceptible to bias arising from the limitations of the included studies.
Exclusive expression of proteasome subunit β5t in the human thymic cortex
Authors: Tomaru Utano , Ishizu Akihiro , Murata Shigeo , Miyatake Yukiko , Suzuki Sayuri , Takahashi Satomi , Kazamaki Taku , Ohara Jiro , Baba Tomohisa , Iwasaki Sari , Fugo Kazunori , Otsuka Noriyuki , Tanaka Keiji , Kasahara Masanori
Published: March 2009

The ubiquitin-proteasome pathway, which degrades intracellular proteins, is involved in numerous cellular processes, including the supply of immunocompetent peptides to the antigen presenting machinery. Proteolysis by proteasomes is conducted by three β subunits, β1, β2, and β5, of the 20S proteasome. Recently, a novel β subunit expressed exclusively in cortical thymic epithelial cells was discovered in mice. This subunit, designated β5t, is a component of the thymoproteasome, a specialized type of proteasomes implicated in thymic positive selection. In this study, we show that, like its mouse counterpart, human β5t is expressed exclusively in the thymic cortex. Human β5t was expressed in approximately 80% of cortical thymic epithelial cells and some cortical dendritic cells. Human β5t was incorporated into proteasomes with two other catalytically active β subunits β1i and β2i, forming 20S proteasomes with subunit compositions characteristic of thymoproteasomes. The present study demonstrates, for the first time, the existence of thymoproteasomes in the human thymic cortex, indicating that thymoproteasome function is likely conserved between humans and mice.
Enantiopure 1,8-Anthrylene Dimer with Acetylene Linkers and an Intraannular Alkyl Group
Authors: Toyota Shinji , Onishi Hiroyuki , Wakamatsu Kan , Iwanaga Tetsuo
Published: March 2009

The title cyclic compound with an intraannular ethyl group was synthesized by macrocyclization with the Eglinton coupling and its enantiomers were resolved by chiral HPLC. The high barrier to racemization is discussed in terms of the steric hindrance of the ethyl group with a rigid ring moiety based on the molecular structure optimized by DFT method.
Ferrocene-containing Side Chain Polyrotaxanes Obtained by Radical Copolymerization of Styrenes with Acrylamide with a [2]Rotaxane Structure
Authors: Suzaki Yuji , Murata Shintaro , Osakada Kohtaro
Published: March 2009

Radical copolymerization of styrenes and a [2]rotaxane monomer composed of ferrocene-containing N,N-dialkylacrylamide and dibenzo[24]crown-8-ether (DB24C8) yielded side chain polyrotaxanes.
Understanding Solar Behaviour and its Influence on Climate
Authors: Niroma Timo
Published: March 2009

The quiet Sun of the Maunder Minimum in the latter part of the 1600's is compared to the hyper-active Sun in the 1900's. Solar influence upon Earth's climate in these times of very different sunspot abundance is investigated. A second thread in this study is the possible influence of Jupiter in the observed variability of solar behaviour. Thirdly, is an analysis of the solar condition right now (late 2008) and its possible implications for climate on Earth; including what might be ahead. Last is a critical examination of IPCC's hypothesis that changing atmospheric CO2 concentration is the dominant contributor to changing climate.
The Sun's Role in Regulating the Earth's Climate Dynamics
Authors: Mackey Richard
Published: March 2009

This paper introduces this thesis:

The Sun-Earth system is electromagnetically, magneto-hydrodynamically and gravitationally coupled, dominated by significant non-linear, non-stationary interactions, which vary over time and throughout the three-dimensional structure of the Earth, its atmosphere and oceans. The essential elements of the Sun-Earth system are the solar dynamo, the heliosphere, the lunisolar tides, the Earth's inner and outer cores, mantle, crust, magnetosphere, oceans and atmosphere. The Sun-Earth system is non-ergodic (i.e. characterised by continuous change, complexity, disorder, improbability, spontaneity, connectivity and the unexpected). Climate dynamics, therefore, are non-ergodic, with highly variable climatological features at any one time. A theoretical framework for considering the role of the Sun in relation to the Earth's climate dynamics is outlined and ways in which the Sun affects climate reviewed. The forcing sources (independent variables) that influence climate processes (dependent variables) are analysed. This theoretical framework shows clearly the interaction effects between and amongst the two classes of variables. These seem to have the greatest effect on climate dynamics. Climate processes are interconnected and oscillating, yielding variable periodicities. Solar processes, especially when interacting, amplify or dampen these periodicities producing distinctive climatic cycles. As solar and climate processes are non-linear, non-stationary and non-ergodic, appropriate analytic methodologies are necessary to reveal satisfactorily solar/climate relationships.
Earth's Temperature / Co2 Equilibrium Prior to 1850
Authors: Cropp Martin D.
Published: March 2009

The observed relationship between Earth's temperature and CO2 concentration in the atmosphere during glacial and interglacial periods from 420,000 years ago up to 1850 has still not been satisfactorily explained. It is proven that CO2 movements lag temperature, but why did the concentration move up and down in a regular pattern? No universally accepted conclusion exists that can be reliably used for modelling “what if” scenarios.
Clusterin Expression Correlates With Stage and Presence of Large Cells in Mycosis Fungoides
Authors: Chandra Pranil , Plaza Jose A. , Zuo Zhuang , Diwan A. Hafeez , Koeppen Hartmut , Duvic Madeleine , Medeiros L. Jeffrey , Prieto Victor G.
Published: March 2009

Clusterin expression is common in systemic and cutaneous anaplastic large cell lymphoma (ALCL). Mycosis fungoides (MF) in large cell transformation can resemble ALCL. In this study, we immunohistochemically assessed for clusterin in 97 skin biopsy specimens, including 70 MF cases and 27 other cutaneous neoplasms including ALCL, peripheral T-cell lymphoma unspecified (PTCL), and lymphomatoid papulosis (LyP). Clusterin was positive in 36 (51%) of 70 cases of MF and correlated with clinical stage in 68 cases: 3 of 21 stage I, 11 of 20 stage II, and 23 of 27 stage III/IV. Clusterin expression also correlated with type of skin lesion (3/19 patch, 13/28 plaque, and 20/23 tumor/erythroderma) and number of large cells (6/30 small cell, 12/18 with increased large cells, and 18/22 with large cell transformation). Clusterin expression was not specific for MF as it also was positive in 3 of 3 cases of LyP, 2 of 2 systemic ALCL cases involving skin, 7 of 16 cutaneous ALCLs, and 1 of 6 PTCLs.
Analysis of Bacterial Detection in Whole Blood–Derived Platelets by Quantitative Glucose Testing at a University Medical Center
Authors: McKane A. Victoria , Ward Nancy , Senn Chris , Eubanks Julie , Wessels Linda , Bowman Robert
Published: March 2009

After the March 2004 implementation of American Association of Blood Banks standards regarding platelet bacterial detection, we began quantitative glucose screening of whole blood–derived platelets (WB-P). The glucose level was measured immediately before component release—often storage day 4 or 5—using the Glucometer SureStep Flexx Meter (LifeScan, Milpitas, CA), with a positive cutoff of less than 500 mg/dL; failing units were cultured and not transfused. During 29 months (March 1, 2004–July 31, 2006) 93,073 units of WB-P were tested. Initially, 929 units (0.998%) screened positively. Bacterial growth was culture-confirmed in 6 units, for a bacterial contamination incidence of 0.006% and a true-positive rate of 6.4/100,000. Three additional culture-confirmed contamination cases were detected in transfused units causing febrile nonhemolytic reactions, for a false-negative rate of 3.2/100,000. Our overall contamination prevalence was 9.6/100,000 units of platelets transfused, lower than ordinarily cited, and showed a false-negative rate remarkably congruent to that of culture: 3.2/100,000. A low-sensitivity screening test applied late in platelet shelf-life can be comparable to culture in preventing bacterial-related morbidity.
Adult attachment in bipolar 1 disorder
Authors: Morriss Richard K. , van der Gucht Emma , Lancaster Gillian , Bentall Richard P.
Published: March 2009

Objectives. To determine how security of adult attachment style is related to the mania, major depression and euthymic mood states in bipolar 1 (BP1) disorder.

Design. An observational cross‐sectional study.

Method. One hundred and seven BP1 patients (34 in a manic type episode, 30 in major depressive episode, and 43 in remission) and 41 healthy controls similar in age, gender, reading age, and education were recruited. The groups were compared on self‐reported mean and preferred attachment style controlling for psychiatric comorbidity.

Results. Preferred attachment style was insecure in 84 (78%) BP1 patients but only 13 (32%) healthy controls (χ2=34.3, df=3, and p<.001). Healthy controls reported higher secure attachment, lower anxious, and lower preoccupied attachment scores than all groups of patients with bipolar disorder, although the scores for secure attachment in mania and preoccupied attachment in euthymic patients were not significantly different from healthy controls. Overall, within the bipolar groups, anxious attachment style varied little with mood but mania was associated with higher secure and preoccupied attachment style, and depression with higher preoccupied and lower dismissing attachment style scores.

Conclusions. Insecure attachment is found in most patients with BP1 disorder. Attachment style is affected by mood episodes so it should be assessed when a patient with bipolar disorder is in remission with minimal residual depressive or manic symptoms.
Surface modification of polymers by direct fluorination: A convenient approach to improve commercial properties of polymeric articles
Authors: Kharitonov Alexander P. , Kharitonova Larisa N.
Published: March 2009

The fundamental features and industrial applications of the direct fluorination of polymers are reviewed. Direct fluorination of polymers (i.e., treatment of a polymer surface with gaseous fluorine mixtures) proceeds spontaneously at room temperature and is a surface modification process. More than 25 polymers have been studied with the aid of a variety of analytical and spectroscopic techniques. The fundamental features of the direct fluorination, such as influence of treatment conditions (composition of the fluorinating mixture, fluorine partial pressure, temperature, and fluorination duration) on the rate of formation, chemical composition, density, refraction index, and surface energy of the fluorinated layer, kinetics of formation of radicals during fluorination and their termination, texture of fluorinated layer, etc. were studied. It was demonstrated experimentally that direct fluorination can be effectively used to enhance commercial properties of polymer articles, such as barrier properties of polymer vessels, bottles, and packaging films and envelopes; gas-separation properties of polymer membranes; adhesion and printability properties of polymer articles; and mechanical properties of polymer-based composites.
Confronting Anxiety in Couple and Family Therapy Supervision: A Developmental Supervisory Model Based on Attachment Theory
Authors: Hill E. Wayne
Published: March 2009

Referencing relevant supervisory literature and attachment theory, this article presents a developmental couple and family therapy supervisory model that emphasises the efficacy of the supervisory relationship. Issues concerning anxiety, cognition and learning theory are addressed and phases in the supervisory process are identified and described. Cognitive, emotional and social development are linked to attachment theory and discussed in the supervisory context.
Use of Structural Models as an Alternative to Full-Scale Testing
Authors: Harris HG
Published: March 2009

A brief review is given of the requirements to be met by small-scale direct models in duplicating the behavior of actual structures up to ultimate failure. It is found that the requirements on similitude, model materials, fabrication, and testing techniques are more restrictive in model studies where nonlinear structural behavior is the primary goal. The paper discusses current methods of structural modeling for the most common structural forms, materials of construction and loading. Examples of model studies of a variety of structures, drawn mainly from practical applications of the modeling technique are given. In all the examples chosen, the main objective has been the duplication of the inelastic structural behavior of the anticipated prototype structure under both static or dynamic loads.
Structural Testing of Mobile-Home Roof/Ceiling Assemblies
Authors: Fritz TW
Published: March 2009

Unlike roof/ceiling assemblies in conventional single-family homes, the mobile-home assembly normally is not sheathed. Thus the ability of the mobile-home roof structure to resist the forces resulting from lateral wind pressure against the side walls depends upon the diaphragm strength of the ceiling material. The ceiling is the primary element in the roof structure capable of resisting lateral forces along the edge of the roof diaphragm. In a mobile home, the ceiling performs not only a decorative function, but a structural one as well.

To evaluate the structural properties of mobile-home roof/ceiling assemblies, full-scale tests were conducted. Actual sections of mobile-home roof structures up to 3.66 by 8.53 m (12 by 28 ft) were tested, using a self-contained hydraulic test apparatus.

The results of the full-scale tests are translated into permissible shear wall spacings within the mobile home. The required diaphragm shear values depend on the anticipated wind loading on the mobile home and the desired shear wall spacing.

This paper discusses the origin of the test requirements in the codes and the development and design of the test frame and the loading system. Typical data from the tests and the application of the test results for mobile-home construction are also discussed.
Storage and Disposal of Oily Waste in Alaska
Authors: Hillman SOJ
Published: March 2009

Disposal of waste oil and oily debris is a key factor in any spill cleanup activity as well as a day-to-day operational problem. The environmental conditions encountered in Alaska, such as tundra, permafrost, and arctic climate, often require modifications of current state-of-the-art disposal methods employed in other regions. This presentation gives an overview of the methods of storage and disposal of waste oil products presently utilized in Alaska. Because of the limited data base available, this paper does not cover in any detail the quantities of oil handled by any single technique or the costs involved. The summary includes recommendations for future research and demonstration projects.
An Automated Biological Monitoring Facility for Rapidly and Continuously Assessing Industrial Effluents
Authors: Gruber D , Dickson KL , Hendricks AC , Miller WR
Published: March 2009

A continuous and automatic biological monitoring facility has been developed to measure the toxicity of industrial effluents to aquatic organisms. The ventilatory rates of bluegill sunfish, Lepomis macrochirus, are monitored with the aid of a minicomputer. The biomonitoring and auxiliary components have been housed within a 9.75 by 3.66-m (32 by 12-ft) trailer to facilitate on-site monitoring. Other incorporations include a continuous-flow acute bioassay unit, probes for monitoring conductivity, dissolved oxygen, pH, and temperature, and an automatic water sampler. Initial testing employing the petroleum industry's arbitrary reference mixture, two synthetic chlorinated effluents, and an effluent from a U.S. Army ammunition plant has demonstrated the potential of the present system for monitoring industrial wastewaters.
Selected Heavy Metals in Sediments and Biota from Desert Streams of the Gila River Drainage (Arizona)
Authors: Lewis MA
Published: March 2009

The distribution and bioaccumulation of heavy metals in mine-polluted and nonpolluted desert streams was studied during 1975 and 1976. Heavy metal concentrations in reference streams were less than the detection limits; however, periodic input of mining and milling wastes increased the zinc, copper, manganese, and iron in receiving test streams to above this level. Copper and, to a lesser extent, managanese concentrations were higher in samples of sediment and biota collected from contaminated waters (P < 0.05). The copper concentration was twelve times higher in biota collected from metal-contaminated waters than an identical species collected from reference areas. Fish viscera, fish eggs, and eviscerated fish in mine-impacted streams also contained a higher copper content. In contrast, concentrations of iron, cadmium, lead, and mercury were similar in all samples. The distributions of copper, manganese, and iron in the trophic levels were similar; consumer organisms concentrated less metal than did the sediments of primary producers. An exception was zinc, which achieved its highest concentration in the middle trophic levels. Higher copper levels in fish tissue did not effect length-weight relationships or condition values (P > 0.05).
Evaluation of Early Life-Stage Toxicity Tests with Embryos and Juveniles of Sheepshead Minnows (Cyprinodon variegatus)
Authors: Ward GS , Parrish PR
Published: March 2009

Chronic (full life-cycle) toxicity tests have been performed with freshwater fishes during the past decade to obtain data for the establishment of water quality criteria. More recently, chronic tests have been performed with a saltwater fish, the sheepshead minnow. Examination of the results of chronic tests has lead to the development of shorter, early life-stage tests for both fresh and saltwater species to estimate specific application factors (the ratio of chronic: acute toxicity). The criteria for toxic effect utilized in the early life-stage tests are hatching success, juvenile mortality, and juvenile growth. We found that the growth of sheepshead minnows during early life-stage tests was not a statistically sensitive indicator of effect in 16 of 18 (89 percent) tests surveyed. In only one test was growth found to be a more sensitive indicator of toxic effect than was juvenile mortality, and thus necessary for establishing the estimated maximum acceptable toxicant concentration. Since in all the early life-stage tests reviewed, 95 percent of all mortality had occurred by Day 14 after hatching, we suggest that early life-stage tests with sheepshead minnows be shortened to 14 days after hatching and growth be eliminated as an indicator of toxic effect. This would substantially reduce the time and effort expended, and ultimately the cost, in arriving at reasonable specific application factors for sheepshead minnows when the chemical being tested does not exhibit cumulative toxicity and has a single mode of action.
Studies to Determine Relationships Between Time and Toxicity of an Acidic Effluent and an Alkaline Effluent to Two Estuarine Species
Authors: Hollister TA , Heitmuller PT , Parrish PR , Dyar EE
Published: March 2009

Acute tests (0.25 to 96 h) and chronic (full life-cycle) tests were conducted with mysid shrimp (Mysidopsis bahia) and sheepshead minnows (Cyprinodon variegatus) to determine the toxicity of an acidic effluent and an alkaline effluent.

In acute tests with the acidic effluent, the unaltered effluent (pH <0.1) was much more toxic to shrimp and fish than was the pH-adjusted effluent (pH 7 ± 0.2). However, both shrimp and fish were similar in their sensitivity to each of the test materials. Also, three life stages (juvenile, subadult, and adult) of sheepshead minnows exposed to both unaltered and pH-adjusted effluent were very similar in their sensitivity to each of the test materials.

In acute tests with the alkaline effluent, there was little difference between the toxicity of the unaltered effluent (pH 13.0) and that of the pH-adjusted effluent (pH 8.0) to shrimp or fish. Similarly, there was little difference in the sensitivities of the three life stages (juvenile, subadult, and adult) of sheepshead minnows exposed to unaltered or pH-adjusted effluent.

During a chronic exposure of mysid shrimp to the acidic effluent, concentrations of unaltered effluent ≤75 ppm (µl/litre) caused no adverse effects, and in a chronic exposure of sheepshead minnows to the unaltered effluent, concentrations ≤100 ppm caused no adverse effects.

Exposure to concentrations of the pH-adjusted alkaline effluent ≤750 ppm caused no adverse effect on mysid shrimp or sheepshead minnows during chronic exposures. Histopathological examination of the fish from the chronic test showed no effluent-related effects.
Short-Term Toxicity of Aqueous Hydrogen Sulfide to Representative Fish Species of Lake Huron
Authors: Fung DK , Bewick PH
Published: March 2009

The toxicity of aqueous hydrogen sulfide on the fish community in Lake Huron was measured on two life stages of three representative species—whitefish (Coregonus clupeaformis), yellow perch (Perca flavescens), largemouth bass (Micropterus salmoides)—and on three stages of rainbow trout (Salmo gairdneri). The experiments were carried out to simulate existing discharge conditions from a heavy water production plant which uses hydrogen sulfide as an extraction medium.

LC50 tests at various time intervals under selected conditions were completed to evaluate the toxic effects at various parts of a thermal plume discharged into Lake Huron.

The results are discussed in terms of life stages, species, pH changes, and avoidance reactions. These data are also compared with data obtained from reports of experiments on toxicity at dissolved oxygen levels lower than those tested in this study. The sensitivity of the different fish species to unionized hydrogen sulfide varied from 0.002 to 0.063 mg/litre in the 96-h exposures and from 0.046 to 1.719 mg/litre in the 1-h tests. The results demonstrate the sensitivity of all life stages of the experimental organisms and indicate that simulation of the actual environmental conditions under which the organism is exposed to the toxic substance may be important.
Fast Fracture Simulated by Conventional Finite Elements: A Comparison of Two Energy-Release Algorithms
Authors: Malluck JF , King WW
Published: March 2009

Three problems of constant-speed fast fracture have been simulated by finite-element analyses. The mechanism for the release of mechanical energy was the gradual relaxation of the restraining reaction at a node adjacent to the crack tip. The numerical results are used to compare the performances of two recently proposed methods for prescribing the manner in which the relaxing force depends upon the crack-tip location between nodes in the finite-element model. Energy-release rates generated from the algorithm proposed by Rydholm et al are found to be in slightly better accord with continuum elastodynamics than are those produced by the algorithm previously proposed by the authors.
Experimental Analysis of Dynamic Effects in Different Crack Arrest Test Specimens
Authors: Kalthoff JF , Beinert J , Winkler S , Klemm W
Published: March 2009

For different crack arrest test specimens, the influence of dynamic effects on the crack arrest process is investigated. Utilizing the shadow optical method of caustics, actual dynamic stress-intensity factors directly before, at, and after arrest were measured. In the first part of the investigation, specimens made from the model material Araldite B were analyzed. It was found that the dynamic effects, that is, the difference between statically and dynamically determined crack arrest stress-intensity factors, are largest for longitudinal wedge-loaded rectangular double cantilever beam specimens, considerably smaller for machine-loaded tapered double cantilever beam specimens, and smallest for transverse wedge-loaded compact specimens. In the second part of the paper, the behavior of arresting cracks in high-strength steel specimens was investigated. The overall dynamic effects on the crack arrest process were found to be similar to those in Araldite B, but in steel the oscillation of the dynamic stress-intensity factor after arrest shows higher-frequency disturbances and is damped out only after much longer times.
Fast Fracture: An Adiabatic Restriction on Thermally Activated Crack Propagation
Authors: Burns SJ
Published: March 2009

Slow, isothermal crack propagation is widely suspected to be rate-controlled by thermally activated plastic deformation in the crack-tip region. Adiabatic conditions are generally established in the fracture-modified material at the tip of a crack during fast fracture. The temperature of this material is not the temperature of the specimen and is generally not measured during fast fracture. Thus, a complete thermodynamic description of adiabatic crack propagation data cannot be made. When the slow, isothermal crack propagation mechanisms are assumed to be operative during adiabatic crack propagation, then certain predictions can be made. For example: the changes in ς due to temperature and rate are always in the opposite sense; there is no minimum in ς versus crack velocity without a change in mechanism; the temperature rise in the crack-tip fracture-modified material is determined mainly by the activation enthalpy for crack propagation; the interpretation of fast fracture structural steel data from simple plastic models is suspect since these materials have dissimilar isothermal temperature dependencies.
KId-Values Deduced from Shear Force Measurements on Double Cantilever Beam Specimens
Authors: Chow C-L , Burns SJ
Published: March 2009

Time-varying shear force measuring techniques have been used to investigate the dynamic critical stress-intensity factor versus crack propagation velocity curve. The product of the shear force at the loading end times the square root of the loading time on a rapidly wedged double cantilever beam specimen is uniquely related to the critical bending moment at the crack tip. Static compliance measurements on side-grooved specimens were incorporated into a Bernoulli-Euler beam model for calibration purposes and to eliminate the inappropriate built-in beam assumption. The compliance calibration shows a crack length shift from a measured crack length to a beam model length at a fixed compliance value. This shift does not affect the magnitude of the calculated critical bending moment at the crack tip when the load and the load-point displacement are measured quantities. The effective crack length is calculated from the beam model length with the length shift correction. The KId-values (calculated from the critical bending moment) versus crack velocity have been investigated at several test temperatures for a low-carbon steel. KId-values show a generally decreasing trend when crack velocity increases. KIc at fast fracture initiation is larger than the corresponding KId-value for all tests recorded.
Ranking 7XXX Aluminum Alloy Fatigue Crack Growth Resistance Under Constant Amplitude and Spectrum Loading
Authors: Bucci RJ , Thakker AB , Sanders TH , Sawtell RR , Staley JT
Published: March 2009

Fatigue crack growth (FCG) experiments were conducted on controlled variations of Type 7075 and 7050 aluminum alloys. Alloy FCG resistance was ranked under constant amplitude and simple variable amplitude load spectra. Fracture mechanics and fractographic approaches were used to interpret causes for variation in ranking of 7XXX aluminum alloy FCG resistance with loading conditions. The interpretation is built around clarification of a controlling FCG mechanism that is dependent upon interaction of microstructure and load history. This clarification represents a necessary first step toward knowing which microstructure or which design (test) procedure is optimum for a particular class of application, for example, fighter as opposed to bomber or transport aircraft.
Effects of Fighter Attack Spectrum on Crack Growth
Authors: Dill HD , Saff CR , Potter JM
Published: March 2009

The purpose of this program was to systematically evaluate the effect of variations in flight stress spectra on crack propagation using analysis in conjunction with experimental correlations. Over 100 spectrum variations were generated, derived from four baseline load factor spectra. Three constant amplitude and 30 spectrum tests were performed to verify predictions of the effects of spectrum variations and to provide data useful in defining guidelines for structural verification of future aircraft. Spectrum variations shown to have the greatest impact on crack growth life are those affecting the maximum peak stresses.
X-Ray Phosphors and Screens
Authors: Kingsley JD
Published: March 2009

Most radiologic imaging utilizes a phosphor as the primary X-ray absorber. The absorption of the X-ray, subsequent X-ray fluorescence and Auger relaxation, and the diffusion and scattering of secondary electrons influence the effective X-ray absorption and the picture noise. Scattering, diffusion, and absorption of the light within the phosphor layer and at its surfaces, and the optical coupling to the photoemitter, photoconductor, or photographic film, influence the sensitivity, noise level, contrast, and resolution of the imaging system. The best X-ray phosphors convert about 20 to 25 percent of the energy of an X-ray into useful radiant energy. The “speed” of phosphor layers has been increased about four times in the past decade. Our understanding of the limitations on their efficiency is incomplete but it is unlikely that materials having efficiencies much inexcess of 25 percent can be found. The quantum absorption in X-ray phosphor screens is clearly important to reducing the statistical noise, or the X-ray dose. While the need for good quantum efficiency is generally well understood, it is less well known that the variability of the amount of light detected between separate X-ray events can seriously reduce the signal-to-statistical noise ratio, even when the quantum absorption is nearly unity. A variation from pulse to pulse causes an additional statistical fluctuation so that the X-ray receptor behaves as though it were absorbing a smaller percentage of the X-ray quanta. The “noise-equivalent absorption” is the most meaningful measure of the degree to which an X-ray receptor preserves statistical information present in the X-ray signal incident on the device. The X-ray absorption is maximized by choosing a phosphor host which has elements with X-ray absorption edges in the most useful energy range, the greatest density, and the greatest thickness possible. Since the modulation transfer function and the limiting resolution decrease monotonically with layer thickness, a compromise between X-ray absorption and resolution must be made. Techniques are now being developed for fabricating screens containing isolated phosphor columns which can “pipe” the light through a thick layer without losing resolution.
Basic Limits in Real-Time Industrial Radiographic Systems
Authors: Kuriyama M , Boettinger WJ , Burdette HE
Published: March 2009

Industrial applications of radiography presently demand improvements in resolution when radiographic images are viewed on a real-time basis. Unlike medical applications (radiology), the dosage of incoming X-rays or gamma-rays does not impose serious restrictions in industrial applications. In addition, many advances in the area of computer-assisted intensification of image signals allow us to reexamine the present techniques of radiography from a fresh viewpoint. As a consequence, we may be able to make a major advance in the improvement of resolution in real-time radiography. In this paper, we discuss (1) collimation of primary radiation, including apparent size of sources, (2) monochromatic radiography to obtain true signals, (3) resolution improvement by a magnification of X-ray images before the radiation reaches the detecting (or viewing) system and, briefly, (4) intensification of signals when crystal collimation is used.
A Real-Time X-Ray Topography System
Authors: Hartmann W
Published: March 2009

Real-time or “live” topography of single-crystalline solids is a direct method to image the fine structure within Laue diffraction spots being generated by deviations from perfection of a crystal lattice, for example, by dislocations. We describe a direct display system which is operative at this institution. A 6-μm-thick fluorescent screen converts the X-ray pattern into an optical image. This optical picture is imaged onto the target of a low-light-level television camera through a magnifying optical system. A digital image processing equipment integrates the video pictures. Time resolution can be thus varied between 20 ms and 5 s in order to achieve a better signal-to-noise ratio, and, therefore, a better spatial resolution. The detector system has a spatial resolution of about 10 μm. The added and stored picture is rendered visible on a television monitor.

A movie shows at first a comparison between integrated and direct pictures. Then, a dislocation array is created above 1273 K by the strain field of an indentation. The indentation is made at room temperature on the silicon specimen. Last, we show the high-temperature behavior of strain fields at the edges of oxide layers grown on silicon substrates.
Real-Time Optical Processing: Automatized Optical Plotter and Interferometric Device for 3D-Imaging
Authors: Landraud AM , Clair JJ
Published: March 2009

In this paper we are interested in reconstructing, by optical methods, a three-dimensional spatial distribution of a local parameter such as an attenuation coefficient or small differences in the refractive index of objects which are relatively transparent to electromagnetic energy.

We present a computer-controlled optical tracing system to produce the different-amplitude filters needed for the optical treatment and an interferometric device for scanning phase objects.

A new technique for coding image data allows the reconstruction of 3D-amplitude and phase objects to be performed without long and expensive numerical treatments.
Neutron Diffraction Tomography: A Unique 3D Inspection Technique for Crystals Using an Intensifier TV System
Authors: Davidson JB , Case AL
Published: March 2009

This paper describes the application of phosphor-intensifier-television (TV) techniques to neutron topography and tomography of crystals. The older, analogous X-ray topography using wavelengths ≈ 1.5Å is widely used for surface inspection. However, the crystal must actually be cut in order to see diffraction anomalies beneath the surface. Because 1.5-Å thermal neutrons are highly penetrating, much larger and thicker specimens can be used. Also, since neutrons have magnetic moments, they are diffracted by magnetic structures within crystals. In neutron volume topography, the entire crystal or a large part of it is irradiated, and the images obtained are superimposed reflections from the total volume. In neutron diffraction tomography (or section topography), a collimated beam irradiates a slice (0.5 to 10 mm) of the crystal. The diffracted image is a tomogram from this part only. A series of tomograms covering the crystal can be taken as the specimen is translated in steps across the narrow beam. Grains, voids, twinning, and other defects from regions down to 1 mm in size can be observed and isolated. Although at present poorer in resolution than the original neutron and film methods, the TV techniques are much faster and, in some cases, permit real-time viewing. Two camera systems are described: a counting camera having a 150-mm 6Li-ZnS screen for low-intensity reflections which are integrated in a digital memory, and a 300-mm system using analog image storage. Topographs and tomograms of several crystals ranging in size from 4 to 80 mm are shown.