bluuebunny/crossref_metadata_2025 huggingface dataset:
Independent Thinking: A Path to Outstanding Scholarship
Authors: Chen Xiao-Ping
Published: August 2008

This editorial essay addresses the importance of independent thinking in the process of developing outstanding scholarship. Through analysing the difficulties of maintaining independent thinking in the Chinese culture, the paper proposes four approaches: understanding the power of the minority; transforming outside pressure into intrinsic motivation; listening with an open mind; and developing a passion for research.
Local Dependence in an Operational CAT: Diagnosis and Implications
Authors: Pommerich Mary , Segall Daniel O.
Published: August 2008

The accuracy of CAT scores can be negatively affected by local dependence if the CAT utilizes parameters that are misspecified due to the presence of local dependence and/or fails to control for local dependence in responses during the administration stage. This article evaluates the existence and effect of local dependence in a test of Mathematics Knowledge. Diagnostic tools were first used to evaluate the existence of local dependence in items that were calibrated under a 3PL model. A simulation study was then used to evaluate the effect of local dependence on the precision of examinee CAT scores when the 3PL model was used for selection and scoring. The diagnostic evaluation showed strong evidence for local dependence. The simulation suggested that local dependence in parameters had a minimal effect on CAT score precision, while local dependence in responses had a substantial effect on score precision, depending on the degree of local dependence present.
Simulated Tests of Differential Item Functioning Using SIBTEST With and Without Impact
Authors: Klockars Alan J. , Lee Yoonsun
Published: August 2008

Monte Carlo simulations with 20,000 replications are reported to estimate the probability of rejecting the null hypothesis regarding DIF using SIBTEST when there is DIF present and/or when impact is present due to differences on the primary dimension to be measured. Sample sizes are varied from 250 to 2000 and test lengths from 10 to 40 items. Results generally support previous findings for Type I error rates and power. Impact is inversely related to test length. The combination of DIF and impact, with the focal group having lower ability on both the primary and secondary dimensions, results in impact partially masking DIF so that items biased toward the reference group are less likely to be detected.
When Adaptation Is Not an Option: An Application of Multilingual Standard Setting
Authors: Davis Susan L. , Buckendahl Chad W. , Plake Barbara S.
Published: August 2008

As an alternative to adaptation, tests may also be developed simultaneously in multiple languages. Although the items on such tests could vary substantially, scores from these tests may be used to make the same types of decisions about different groups of examinees. The ability to make such decisions is contingent upon setting performance standards for each exam that allow for comparable interpretations of test results. This article describes a standard setting process used for a multilingual high school literacy assessment constructed under these conditions. This methodology was designed to address the specific challenges presented by this testing program including maintaining equivalent expectations for performance across different student populations. The validity evidence collected to support the methodology and results is discussed along with recommendations for future practice.
Testing Students with Special Needs: A Model for Understanding the Interaction Between Assessment and Student Characteristics in a Universally Designed Environment
Authors: Ketterlin‐Geller Leanne R.
Published: August 2008

This article presents a model of assessment development integrating student characteristics with the conceptualization, design, and implementation of standardized achievement tests. The model extends the assessment triangle proposed by the National Research Council (Pellegrino, Chudowsky, & Glaser, 2001) to consider the needs of students with disabilities and English learners on two dimensions: cognitive interaction and observation interaction. Specific steps in the test development cycle for including students with special needs are proposed following the guidelines provided byDowning (2006). Because this model of test development considers the range of student needs before test development commences, student characteristics are supported by applying the principles of universal design and appropriately aligning accommodations to address student needs. Specific guidelines for test development are presented.
Building and Supporting a Validity Argument for a Standards‐Based Classroom Assessment of English Proficiency Based on Teacher Judgments
Authors: Llosa Lorena
Published: August 2008

Using an argument‐based approach to validation, this study examines the quality of teacher judgments in the context of a standards‐based classroom assessment of English proficiency. UsingBachman's (2005)assessment use argument (AUA) as a framework for the investigation, this paper first articulates the claims, warrants, rebuttals, and backing needed to justify the link between teachers' scores on the English Language Development (ELD) Classroom Assessment and the interpretations made about students' language ability. Then the paper summarizes the findings of two studies—one quantitative and one qualitative—conducted to gather the necessary backing to support the warrants and, in particular, address the rebuttals about teacher judgments in the argument. The quantitative study examined the assessment in relation to another measure of the same ability—the California English Language Development Test—using confirmatory factor analysis of multitrait‐multimethod data and provided evidence in support of the warrant that states that the ELD Classroom Assessment measures English proficiency as defined by the California ELD Standards. The qualitative study examined the processes teachers engaged in while scoring the classroom assessment using verbal protocol analysis. The findings of this study serve to support the rebuttals in the validity argument that state that there are inconsistencies in teachers' scoring. The paper concludes by providing an explanation for these seemingly contradictory findings using the AUA as a framework and discusses the implications of the findings for the use of standards‐based classroom assessments based on teacher judgments.
Raju's Differential Functioning of Items and Tests (DFIT)
Authors: Oshima T. C. , Morris S. B.
Published: August 2008

Nambury S. Raju (1937–2005) developed two model‐based indices for differential item functioning (DIF) during his prolific career in psychometrics. Both methods, Raju's area measures (Raju, 1988) and Raju's DFIT (Raju, van der Linden, & Fleer, 1995), are based on quantifying the gap between item characteristic functions (ICFs). This approach provides an intuitive and flexible methodology for assessing DIF. The purpose of this tutorial is to explain DFIT and show how this methodology can be utilized in a variety of DIF applications.
Effects of arc3, arc5 and arc6 Mutations on Plastid Morphology and Stromule Formation in Green and Nongreen Tissues of Arabidopsis thaliana†
Authors: Holzinger Andreas , Kwok Ernest Y. , Hanson Maureen R.
Published: August 2008

Mutations in the ARC3, ARC5 and ARC6 genes of Arabidopsis  thaliana affect chloroplast division. We investigated whether ARC3, ARC5 and ARC6 are also involved in determining plastid morphology in nongreen tissues, where stromules, stroma‐filled tubular extensions of the plastid envelope membrane, are more abundant than in mesophyll cells. Using plastid‐targeted green fluorescent protein to observe plastids throughout the organs of these mutants, we have discovered a number of new mutant phenotypes. The size of arc3 plastids was heterogeneous in various tissues. arc5 plastids appeared wild‐type in the majority of nongreen tissues examined. However, in cells of stamen filaments, the arc5 mutant showed an increase in the frequency of stromules. Increased stromule frequency was observed for a number of organs in the arc6 mutant. Some arc6 cells contained heterogeneous mixtures of plastids; epidermal cells of hypocotyls, stamen filaments and the bases of petals possessed both very large chloroplasts as well as much smaller nongreen plastids. Quantitative analysis in hypocotyl cells revealed that the alteration in stromule length in arc3 and arc6 mutants occurred despite wild‐type plastid densities. Thus, in hypocotyls, the effects of the arc3 and arc6 mutations on stromule length and frequency are independent of changes in plastid division. Although electron micrographs of stromules emanating from chloroplasts have rarely been reported, within the arc3 mutant, narrow, 40–50 nm diameter, recoiled stromules could be followed for about 10 μm in electron micrographs of leaf tissue.
Development of polymorphic microsatellite markers for the New Zealand black stilt (Himantopus novaezelandiae) and cross‐amplification in the pied stilt (Himantopus himantopus leucocephalus)
Authors: STEEVES TAMMY E. , HALE MARIE L. , GEMMELL NEIL J.
Published: August 2008

Eight polymorphic microsatellite primer pairs were developed for the critically endangered New Zealand black stilt, Himantopus novaezelandiae, representing the first microsatellite markers available for birds in the family Recurvirostridae. The number of alleles ranged from two to four per locus. Observed and expected heterozygosities ranged from 0.30 to 0.80 and from 0.37 to 0.70, respectively. All eight loci were polymorphic in the related species Himantopus himantopus leucocephalus, indicating these primer pairs may be useful for additional taxa in the globally distributed genus Himantopus.
Microsatellite markers for the fungal banana pathogens Mycosphaerella fijiensis, Mycosphaerella musicola and Mycosphaerella eumusae
Authors: ZAPATER M‐F. , DUCHEMIN M. , DUSSART J‐F. , COSTE D. , BROTTIER P. , CARLIER J.
Published: August 2008

We developed a total of 50 microsatellite markers for the three fungal pathogens causing the most important leaf spot diseases of banana: 32 loci for Mycosphaerella fijiensis are presented, and nine loci each for Mycosphaerella musicola and Mycosphaerella eumusae. All these loci were polymorphic within each species on a sample of isolates collected from various locations around the world. Within M. fijiensis and M. musicola, most of the loci tested (> 80%) in a sample of isolates from a single location in Cameroon were also polymorphic. Multiplex polymerase chain reaction systems were developed with 15 loci for M. fijiensis.
Ten polymorphic microsatellite loci for Allobates femoralis, an Amazonian dendrobatoid frog
Authors: JEHLE R. , GASSER H. , PFUNDER M. , AMÉZQUITA A. , LIMA A. P. , HÖDL W.
Published: August 2008

Within the anuran amphibians, dendrobatoids (poison‐arrow frogs) are renowned for their parental care, but the lack of highly variable DNA markers so far precluded precise and comprehensive measurements of their genetic mating system. Here we present 10 polymorphic microsatellites for Allobates femoralis, a widespread dendrobatoid from the Amazon basin. In 24 field‐collected individuals, we found between seven and 15 alleles per locus, without deviations from Hardy‐Weinberg equilibrium or linkage disequilibrium. The loci will be employed to quantify reproductive success in view of male territoriality and female mate choice, as well as to determine the fine‐scale genetic structure of local populations.
Endoscopic thermal ablation therapies for hepatocellular carcinoma: a multi‐center study
Authors: Sakaguchi Hiroki , Seki Shuichi , Tsuji Kunihiko , Teramoto Kenichi , Suzuki Masatoshi , Kioka Kiyohide , Isoda Norio , Ido Kenichi ,   The Japan Society for Laparoscopic Therapy Research
Published: August 2008

Aim:  The differing efficacies of radiofrequency ablation and microwave coagulation for hepatocellular carcinoma (HCC) are unknown. Therefore, we performed a multi‐center study to assess the factors contributing to survival and local recurrences of HCC among patients with solitary tumors who underwent endoscopic thermal ablation as their primary treatment.

Methods:  From six institutions, 391 patients with solitary HCC who were first treated by endoscopic thermal ablation were enrolled in this study and assessed retrospectively. We investigated age, gender, location of tumor, longest diameter of tumor, method of anesthesia, type of endoscope, method of thermal ablation, Child–Pugh classification, the Japan Integrated Staging score and the Cancer of the Liver Italian Program score. Statistical analyses were performed using univariate analysis with log–rank test and multivariate analysis with the Cox proportional hazards model.

Results:  On univariate analysis, advanced Child–Pugh score, advanced Italian Program score and local recurrences were significant predictors of poor survival. Young age (≤70), large tumor (>30 mm) and the use of the thoracoscopic approach were significant predictors for the development of local recurrence. On multivariate analysis, local anesthesia and advanced Child–Pugh score were independent predictors of poor survival. Young age, large tumor, local anesthesia and the use of the thoracoscopic approach were independent predictors for the development of local recurrence. The method of thermal ablation did not influence survival or local recurrence.

Conclusions:  Differences in the effect on survival and local recurrence between microwave and radiofrequency were not observed in this retrospective, multi‐center study of endoscopic thermal ablation for HCC.
Development and Application of a Complete Multijet Common-Rail Injection-System Mathematical Model for Hydrodynamic Analysis and Diagnostics
Authors: Catania Andrea E. , Ferrari Alessandro , Manno Michele
Published: August 2008

A rather complete mathematical model for a common-rail injection-system dynamics numerical simulation was developed to support experimentation, layout, and control design, as well as performance optimization. The thermofluid dynamics of the hydraulic-system components, including rail, connecting pipes, and injectors was modeled in conjunction with the solenoid-circuit electromagnetics and the mechanics of mobile elements. One-dimensional flow equations in conservation form were used to simulate wave propagation phenomena throughout the high-pressure connecting pipes, including the feeding pipe of the injector nozzle. In order to simulate the temperature variations due to the fuel compressibility, the energy equation was used in addition to mass conservation and momentum balance equations. Besides, the possible cavitation phenomenon effects on the mass flow rate through the injector bleed orifice and the nozzle holes were taken into account. A simple model of the electromagnetic driving circuit was used to predict the temporal distribution of the force acting on the pilot-valve anchor. It was based on the experimental time histories of the current through the solenoid and of the associated voltage that is provided by the electronic control unit to the solenoid. The numerical code was validated through the comparison of the prediction results with experimental data, that is, pressure, injected flow rate, and needle lift time histories, taken on a high performance test bench Moehwald-Bosch MEP2000-CA4000. The novel injection-system mathematical model was applied to the analysis of transient flows through the hydraulic circuit of a commercial multijet second-generation common-rail system, paying specific attention to the wave propagation phenomena, to their dependence on solenoid energizing time and rail pressure, as well as to their effects on system performance. In particular, an insight was also given into the model capability of accurately predicting the wave dynamics effects on the rate and mass of fuel injected when the dwell time between two consecutive injections is varied.
Simulating Area Conservation and the Gas-Wall Interface for One-Dimensional Based Diesel Particulate Filter Models
Authors: Depcik Christopher , Assanis Dennis
Published: August 2008

Researchers have been using one-dimensional based models of diesel particulate filters (DPFs) for over two decades with good success in comparison to measured experimental data. Recent efforts in literature have expanded the classical model to account for the effects of varying soot layer thickness on the flow area of the gases. However, some discrepancies exist with respect to this formulation and the physical phenomena modeled in the channel equations. In addition, there is still some discussion regarding the calculation of the gas temperature within the soot and wall layers. As a result, this paper presents a model to discuss these different phenomena to remove or validate previous assumptions. In specific, formulation of the flow equations in area-conserved format (or quasi-one-dimensional) allows the model to account for the changes in the gaseous area as a function of soot loading. In addition, imposing thermodynamic equilibrium at the interface of the channels and wall layers allows the model to capture the thermal entrance lengths. These tasks were undertaken to illustrate whether or not the results justify the effort is worthwhile and this additional complexity needs to be incorporated within the model. By utilizing linear density interpolation in the wall to increase the computational efficiency of the code, it was determined that the classical model assumptions of neglecting soot thickness and gas temperature in the wall are valid within the range of typical DPF applications.
An Improved Phenomenological Soot Formation Submodel for Three-Dimensional Diesel Engine Simulations: Extension to Agglomeration of Particles into Clusters
Authors: Boulanger Joan , Neill W. Stuart , Liu Fengshan , Smallwood Gregory J.
Published: August 2008

An extension to a phenomenological submodel for soot formation to include soot agglomeration effects is developed. The improved submodel was incorporated into a commercial computational fluid dynamics code and was used to investigate soot formation in a heavy-duty diesel engine. The results of the numerical simulation show that the soot oxidation process is reduced close to the combustion chamber walls, due to heat loss, such that larger soot particles and clusters are predicted in an annular volume at the end of the combustion cycle. These results are consistent with available in-cylinder experimental data and suggest that the cylinder of a diesel engine must be split into several volumes, each of them with a different role regarding soot formation.
Controlling Backfire for a Hydrogen-Fueled Engine Using External Mixture Injection
Authors: Huynh T. C. , Kang J. K. , Noh K. C. , Lee Jong T. , Caton J. A.
Published: August 2008

The development of a hydrogen-fueled engine using external mixture injection (e.g., using port or manifold fuel injection) with high efficiency and high power is dependent on the control of backfire. This work has developed a method to control backfire by reducing the valve overlap period while maintaining or improving engine performance. For this goal, a single-cylinder hydrogen-fueled research engine with a mechanical continuous variable valve timing system was developed. This facility provides a wide range of valve overlap periods that can be continuously and independently varied during firing operation. By using this research engine, the behavior of backfire occurrence and engine performance are determined as functions of the valve overlap period for fuel-air equivalence ratios between 0.3 and 1.2. The results showed that the developed hydrogen-fueled research engine with the mechanical continuous variable valve timing system has similar performance to a conventional engine with fixed valve timings, and is especially effective in controlling the valve overlap period. Backfire occurrence is reduced with a decrease in the valve overlap period, and is also significantly decreased even under operating conditions with the same volumetric efficiency. These results demonstrate that decreasing the valve overlap period may be one of the methods for controlling backfire in a hydrogen-fueled engine while maintaining or improving performance.
Time Reversal and Negative Refraction
Authors: Pendry J. B.
Published: August 2008

Time reversal and negative refraction have been shown to be intimately linked processes. We propose a scheme that exploits transitions between positive and negative frequencies to mimic negative refraction at an interface and hence to make a negatively refracting lens. The theory applies equally to electromagnetic and acoustic waves. We also propose an experimental realization, and under ideal circumstances this lens can exhibit subwavelength resolution, limited only by the strength of the time-reversed signal.
Peripheral T cell lymphoma, not otherwise specified: the stuff of genes, dreams and therapies
Authors: Agostinelli C , Piccaluga P P , Went P , Rossi M , Gazzola A , Righi S , Sista T , Campidelli C , Zinzani P L , Falini B , Pileri S A
Published: August 2008

Peripheral T cell lymphomas (PTCL) account for about 12% of lymphoid tumours worldwide. Almost half show such morphological and molecular variability as to hamper any further classification, and to justify their inclusion in a waste-basket category termed “not otherwise specified (NOS)”. The latter term is used for neoplasms with aggressive presentation, poor response to therapy and dismal prognosis. In contrast to B cell lymphomas, PTCL have been the subject of only a limited number of studies to elucidate their pathobiology and identify novel pharmacological approaches. Herewith, the authors revise the most recent contributions on the subject based on the experience they have gained in the extensive application of microarray technologies. PTCL/NOS are characterised by erratic expression of T cell associated antigens, including CD4 and CD52, which have recently been proposed as targets for ad hoc immunotherapies. PTCL/NOS also show variable Ki-67 marking, with rates >80% heralding a worse prognosis. Gene expression profiling studies have revealed that PTCL/NOS derive from activated T lymphocytes, more often of the CD4+ type, and bear a signature composed of 155 genes and related products that play a pivotal role in cell signalling transduction, proliferation, apoptosis and matrix remodelling. This observation seems to pave the way for the use of innovative drugs such as tyrosine kinase and histone deacetylase inhibitors whose efficacy has been proven in PTCL primary cell cultures. Gene expression profiling also allows better distinction of PTCL/NOS from angioimmunoblastic T cell lymphoma, the latter being characterised by follicular T helper lymphocyte derivation and CXCL13, PD1 and vascular endothelial growth factor expression.
What are the features of an expert haematological microscopist?
Authors: Galvani D
Published: August 2008

Aims:

To determine what skills make a good consultant haematological microscopist; to explore how these skills develop during training and to determine whether these skills are maintained following training.

Methods:

Twenty consultant haematologists underwent a semistructured interview to explore these issues. The interviews were transcribed and analysed for common themes using the N-vivo analytic package. This provides rich subjective qualitative data as opposed to hard objective quantitative data.

Results:

Experience, methodicity and interest were the commonest skills mentioned. However, 25% of interviewees admitted they no longer followed a format when reporting. Interviewees agreed they had passed from a hypothetico-deductive to a scheme-inductive diagnostic reasoning model during acquisition of expertise. Only 20% had undertaken refresher training since becoming consultants, but the majority undertake some peer review of their work.

Conclusions:

These skills could form the basis of vocational and revalidation assessments in the practice of haematological microscopy. The elucidation of such skill development can help refine standards and remedial training through the process of “deliberate practice.” Finally, the low uptake of refresher courses for established consultants needs serious consideration.
Failure of first-line eradication treatment significantly increases prevalence of antimicrobial-resistantHelicobacter pyloriclinical isolates
Authors: Romano M , Iovene M R , Russo M I , Rocco A , Salerno R , Cozzolino D , Pilloni A P , Tufano M A , Vaira D , Nardone G
Published: August 2008

Objectives:

Helicobacter pyloriinfection is a major health problem worldwide, and effective eradication of the infection is mandatory. The efficacy of recommended eradication regimens is approximately 70%. To avoid treatment failure and the consequent development of secondary resistance(s), it is important to choose the most appropriate first-line treatment regimen. This choice should also be made based on the knowledge of the antimicrobial resistance peculiar to a given geographical area. We evaluated the prevalence of antimicrobial-resistantH pyloristrains isolated from naive patients and from patients with previous unsuccessful treatments.

Methods:

This study examined 109H pylori-infected subjects (Group 1) who had never received an eradication treatment and 104H pylori-infected subjects (Group 2) who had failed one or more eradication treatments. Resistance to amoxicillin (AMO), tetracycline (TET), clarithromycin (CLA), metronidazole (MET) and levofloxacin (LEV) was determined using the epsilometer test. The significance of differences was evaluated by the χ2 test.

Results:

The prevalence of antimicrobial resistance was 0% versus 3.1% to AMO, 0% versus 2% to TET, 27% versus 41.3% to MET (p<0.05), 18% versus 45.8% to CLA (p<0.05) and 3% versus 14.6% to LEV (p<0.05) in Group 1 vs Group 2, respectively. In Group 2, there was an increased prevalence ofH pyloristrains resistant to multiple antimicrobials.

Conclusions:

This study confirms the high prevalence ofH pyloristrains resistant to CLA and MET, and indicates that unsuccessful treatments significantly increase resistance. Choosing eradication regimens other than standard triple therapy as a first-line therapy should be advisable in areas with high primary antimicrobial resistance prevalence.
Genetic research on rare familial disorders: consent and the blurred boundaries between clinical service and research
Authors: Ponder M , Statham H , Hallowell N , Moon J A , Richards M , Raymond F L
Published: August 2008

Objectives:

To study the consent process experienced by participants who are enrolled in a molecular genetic research study that aims to find new genetic mutations responsible for an apparently inherited disorder.

Design:

Semi-structured interviews and analysis/description of main themes.

Participants:

78 members of 52 families who had been recruited to a molecular genetic study.

Results:

People were well informed about the goals, risks and benefits of the genetic research study but could not remember the consent process. They had mostly been recruited to take part by trusted clinicians or their relatives but had little memory of, or concern about signing consent forms. Families appeared to regard the research as a continuation of their, or their relatives’, clinical care.

Conclusions:

Ethical review should be more flexible in its attitude to consent forms and written information sheets for some sorts of research. For rare genetic disease studies where research has been discussed fully within the clinical setting then the consent obtained at that time could suffice rather than needing extra consent at a later stage. However, clinician-researchers will need to ensure that their duty of care extends for the duration of the research and beyond.
Current knowledge in moral cognition can improve medical ethics
Authors: Tassy S , Le Coz P , Wicker B
Published: August 2008

Physicians frequently face ethical dilemmas when caring for patients. To help them to cope with these, biomedical ethics aims to implement moral norms for particular problems and contexts. As a means of studying the cognitive and neurobiological features underlying the respect for these norms, moral cognitive neuroscience could help us to understand and improve ethical questioning. The article reviews recent developments in the field and presents neurobiological arguments to highlight why some moral rules are universally shared and why some ethical responses are very dependent on context.
The do-not-resuscitate order: associations with advance directives, physician specialty and documentation of discussion 15 years after the Patient Self-Determination Act
Authors: Morrell E D , Brown B P , Qi R , Drabiak K , Helft P R
Published: August 2008

Background:

Since the passage of the Patient Self-Determination Act, numerous policy mandates and institutional measures have been implemented. It is unknown to what extent those measures have affected end-of-life care, particularly with regard to the do-not-resuscitate (DNR) order.

Methods:

Retrospective cohort study to assess associations of the frequency and timing of DNR orders with advance directive status, patient demographics, physician’s specialty and extent of documentation of discussion on end-of-life care.

Results:

DNR orders were more frequent for patients on a medical service than on a surgical service (77.34% vs 64.20%, p = 0.02) and were made earlier in the hospital stay for medicine than for surgical patients (adjusted mean ratio of time from DNR orders to death versus total length of stay 0.30 for internists vs 0.21 for surgeons, p = 0.04). 22.18% of all patients had some form of an advance directive in their chart, yet this variable had no impact on the frequency or timing of DNR ordering. Documentation of DNR discussion was significantly associated with the frequency of DNR orders and the time from DNR to death (2.1 days with no or minimal discussion vs 2.8 days with extensive discussion, p<0.01).

Conclusions:

The physician’s specialty continues to have a significant impact on the frequency and timing of DNR orders, while advance directive status still has no measurable impact. Additionally, documentation of end-of-life discussions is significantly associated with varying DNR ordering rates and timing.
Sleep better than medicine? Ethical issues related to “wake enhancement”
Authors: Ravelingien A , Sandberg A
Published: August 2008

This paper deals with new pharmacological and technological developments in the manipulation and curtailment of our sleep needs. While humans have used various methods throughout history to lengthen diurnal wakefulness, recent advances have been achieved in manipulating the architecture of the brain states involved in sleep. The progress suggests that we will gradually become able to drastically manipulate our natural sleep-wake cycle. Our goal here is to promote discussion on the desirability and acceptability of enhancing our control over biological sleep, by illustrating various potential attendant ethical problems. We draw attention to the risks involved, possible conflicts of interests underlying the development of wake enhancement, and the potential impact on accountability for fatigue related errors.
Physicians as healthcare surrogate for terminally ill children
Authors: Weisleder P
Published: August 2008

The parents of some terminally ill children have reported that being asked to authorise removal of life-sustaining measures is akin to being requested to sign a “death warrant”. This dilemma leaves families not only enduring the grief of losing a loved one, but also with feelings of ambivalence, anxiety and guilt. A straightforward method by which the parents of terminally ill children can entrust the role of healthcare surrogate to the treating physician is presented. The cornerstone of this paradigm is parental awareness that the physician will act in the child’s best interest, even if that means discontinuing life-sustaining measures. The goal is to mitigate parental guilt and fear of misperception, by self and others, of having given up on their child. From a moral standpoint this concept is an appealing option as it conforms to the four basic principles of medical ethics. While laws in the USA and several European nations prevent members of the medical team from taking on the responsibilities of healthcare surrogate for terminally ill patients, formal and informal precedence for this option already exists in France, The Netherlands, Norway, Sweden, Switzerland, and the Canadian province of Manitoba.
Sex selection for social purposes in Israel: quest for the “perfect child” of a particular gender or centuries old prejudice against women?
Authors: Landau R
Published: August 2008

On 9 May 2005, the Israeli Ministry of Health issued guidelines spelling out the conditions under which sex selection by preimplantation genetic diagnosis (PGD) for social purposes is to be permitted in Israel. This article first reviews the available medical methods for sex selection, the preference for children of a specific gender in various societies and the ethical controversies surrounding PGD for medical and social purposes in different countries. It focuses then on the question of whether procreative liberty or parental responsibility should be the centre of attention in this context. Finally, the article critically examines the new Israeli guidelines and their implications for the women undergoing the necessary medical treatments, for the children born as a result, for other members of the family and for society in general.
Suicide by advance directive?
Authors: Sontheimer D
Published: August 2008

The medical response to suicide is generally resuscitation, followed by attempts to maximise the patient's recovery. Care is generally withdrawn when it is futile and there is no hope for recovery. Suicidal patients who have completed an advance directive may complicate matters. Should medical providers not resuscitate a patient with an advance directive who has attempted to commit suicide? If stated wishes for care are ignored in the emergency setting, how should decisions be made over time in the event of a successful resuscitation resulting in the need for prolonged therapy counter to the wishes of the advance directive? What are the merits of the stated the wishes of suicidal patient? What if they were depressed at the time of the advance directive? This case highlights the need for consideration of these and other concerns in the care of patients who commit suicide and have an advance directive.
Abiotic versus Biotic Uptake of Radiophosphorus in Lake Water
Authors: Tarapchak Stephen J. , Slavens David R. , Maloney Lisa M.
Published: August 2008

Tests were conducted on Selenastrum capricornutum and lake water to evaluate the common practice of estimating abiotic uptake of radiophosphorus (33Pi) by poisoning samples with glutaraldehyde (GA) and Formalin (FM) and to estimate abiotic uptake in Lake Michigan water. Algae treated with GA and FM release intracellular 31Pi into solution, which elevates the dissolved 31Pi:33Pi ratio and could seriously underestimate abiotic uptake. Carbonyl-cyanide m-chlorophenylhydrazone (CP), an inhibitor of phosphorylation, was identified as a satisfactory agent for estimating abiotic uptake because it effectively inhibits biological uptake, it does not cause the release of detectable amounts of 31Pi from algae into solution, and it does not appear to block significantly abiotic uptake by particulate material in lake water. Two types of tests demonstrated that nonbiological uptake of 33Pi in water from Lake Michigan was negligible: uptake in samples treated with 10−3 mol/L CP was ≤ 0.01%, and uptake by particulate material recovered from lake water after treatment with heat or GA and resuspension in filtered lake water was ≤ 2% of rates measured in untreated samples. Procedures for estimating abiotic uptake in 33Pi tracer experiments are proposed.Key words: methodology, carbonylcyanide m-chlorophenylhydrazone, Lake Michigan, phosphorus, phytoplankton
Effect of the Algal Length/Aperture Length Ratio on Coulter Analyses of Lake Seston
Authors: Vanderploeg H. A.
Published: August 2008

Experiments on sizing seston and nylon rods in Coulter apertures of different sizes showed that a major difficulty in obtaining a continuous particle-size spectrum for lake seston is the presence of long, thin algae which are significantly undersized unless their lengths are shorter than aperture length. These fibers affect not only the choice of the largest aperture tube required but also the combination of aperture tubes necessary to obtain a continuous particle-size spectrum. Methods are given for selecting aperture tubes and blending the data obtained from them to give a best estimate of the continuous particle-size spectrum.Key words: Coulter counter, multitube technique, lake seston, particle-size analysis, aperture tube selection
Determination of Mineral Fiber Concentrations in Fish Tissues
Authors: Batterman Allan R. , Cook Philip M.
Published: August 2008

Submicroscopic inorganic particle concentrations in tissue have not been quantitatively determined in the past because of a lack of sample preparation techniques capable of achieving the sensitivity required. The determination of whether mineral fibres in water are accumulated in aquatic organisms requires transmission electron microscope examination of bulk tissue residues rather than thin sections. The sample preparation method used for this investigation involved removal of water and organic matter by freeze-drying and low temperature ashing. Lake trout with a lifetime exposure to Lake Superior water containing amphibole fibers contained similar amphibole fibers particularly in the kidney and with low concentrations in muscle tissue. Lake trout from two locations with widely different water fiber concentrations had corresponding differences in tissue fiber concentrations. Analysis of other fish raised under laboratory conditions suggests that ingestion is the primary route for fiber accumulation.Key words: electron microscopy, fiber accumulation, asbestos, lake trout, brook trout, channel catfish, Arctic char
Relationships between Nannoplankton and Lake Trophic Status
Authors: Watson Susan , Kalff Jaap
Published: August 2008

The hypotheses that with increasing eutrophication (1) nannoplankton biomass increases and (2) the relative proportion (percent) of nannoplankton biomass decreases were tested with data from Lake Memphremagog, a lake exhibiting a nutrient gradient, and on a more general scale using published data from a number of lakes. Both hypotheses were supported within and among lakes if trophic status was defined by total algal biomass. This was also generally true if total phosphorus (TP) was used as an alternative measure of trophy, although percent nannoplankton biomass showed no relationship to TP among lakes. Empirical relationships that allow a first prediction of total nannoplankton biomass from total algal biomass or TP were calculated. The data suggest that among lakes, net plankton will show a more variable relationship with TP than nannoplankton.Key words: nannoplankton, net plankton, trophic status, total biomass, total phosphorus
Release of Phosphorus by Certain Benthic Invertebrates
Authors: Gardner Wayne S. , Nalepa Thomas F. , Quigley Michael A. , Malczyk John M.
Published: August 2008

Phosphate release rates by Stylodrilus heringianus, tubificids, and Chironomus spp. were quantified in laboratory experiments by incubating the animals in wet sand under two temperature regimes (5 and 20 °C) and under two nutritional states (full and empty guts). Inorganic phosphorus release rates (± SE) for animals incubated 24 h ranged from 0.12 ± 0.02 (n = 5) nmol phosphorus (P)∙(mg ash-free dry weight)−1∙h−1 for S. heringianus beginning with cleared guts at 5 °C to 0.81 ± 0.09 (n = 5) nmol P∙(mg ash-free dry weight)−1∙h−1 for chironomids beginning with full guts at 20 °C. Calculations based on total invertebrate bio-mass and mean basal release rate suggest that benthic invertebrate excretion could account for most P released from aerobic Lake Michigan sediments.Key words: phosphorus, benthic invertebrates, macroinvertebrates, excretion, nutrients, sediments, nutrient release
Increased Toxicity of Ammonia to Rainbow Trout (Salmo gairdneri) Resulting from Reduced Concentrations of Dissolved Oxygen
Authors: Thurston Robert V. , Phillips Glenn R. , Russo Rosemarie C. , Hinkins Susan M.
Published: August 2008

The median lethal concentration (LC50) of aqueous ammonia at reduced dissolved oxygen (D.O.) concentrations was tested in acute toxicity tests with rainbow trout (Salmo gairdneri) fingerlings. Fifteen 96-h flow-through tests were conducted over the D.O. range 2.6–8.6 mg/L, the former concentration being the lowest at which control fish survived. There was a positive linear correlation between LC50 (milligrams per litre un-ionized ammonia) and D.O. over the entire D.O. range tested; ammonia toxicity increased as D.O. decreased. Ammonia LC50 values were also computed for 12, 24, 48, and 72 h; the correlation with D.O. was greater the shorter the time period.Key words: ammonia toxicity, dissolved oxygen, rainbow trout, Salmo gairdneri
On Estimating Partial Recruitment in Virtual Population Analysis
Authors: Roff Derek A.
Published: August 2008

Virtual population analysis or cohort analysis is hindered by the difficulties of estimating the partial recruitment factors. A method currently used for estimating the latter is the ratio of the frequency of a particular age in the commercial catch to that in a research sample. This method is examined and shown to be only an approximation that may cause significant errors in the analysis. An alternate method, utilizing the same data, is proposed. A method is then given that tests the assumption that the research sample is a random sample from the population.Key words: population estimation, cohort analysis, virtual population analysis, partial recruitment
An Empirical Model to Estimate the Relative Importance of Roots in Phosphorus Uptake by Aquatic Macrophytes
Authors: Carignan R.
Published: August 2008

A simple empirical model for predicting the relative contribution of roots in phosphorus uptake by submersed macrophytes is presented. The model requires only approximate dissolved reactive phosphorus (DRP) concentrations in the sediment pore water and overlying water as inputs and can explain 97% of the observed variance. It has the form: P = 99.8/1 + 2.66 (s/w)−0.83 where P is the relative contribution of the root in phosphorus uptake, s and w are the pore water and overlying water DRP concentrations, respectively. The nonspecificity of the model makes it readily applicable to environmental problems related to the role of macrophytes in phosphorus cycling and suggests a similar phosphorus uptake behavior for morphologically different species.Key words: macrophytes, phosphorus, empirical model
Growth and Maturation of Southwest Nova Scotia Atlantic Herring (Clupea harengus harengus)
Authors: Sinclair M. , Sinclair A. , Iles T. D.
Published: August 2008

Juvenile and adult growth rates, and the maturation schedule, for the southwest Nova Scotia herring stock (NAFO SA 4WX) were investigated over the period 1968–78. The variance in juvenile (age 2) summer growth is not well accounted for by initial weight, juvenile population abundance, and temperature unless a discontinuity in growth pattern starting in 1970 is accounted for. Length at maturity and at recruitment to the adult schools appears to be inversely related to the population abundance experienced during juvenile growth. However, at very low juvenile population size, maturation appears to be inhibited. Somatic growth rate and its year-to-year variability decreases close to an order of magnitude with the onset of maturation. Because of this decrease with age and the radical shifts in age, composition with time, population growth rate fluctuates markedly. Because high population abundance parallels downward shifts in age composition, there is a clear, positive relationship between population growth rate and population abundance. There is a dome-shaped relationship between cohort somatic growth rate and cohort size at intermediate ages, suggesting that over a broad range in population size, adult growth rate is not density-dependent. This growth response is interpreted in relation to planktivorous feeding in a patchy environment. Strong year-class strength variability coupled with a marked decline in somatic growth rate with age results in non-steady state population production. When the age composition is biased towards older ages, catch (defined by F0.1 guidelines) exceeds population production resulting in rapid stock declines. The growth characteristics of herring are discussed in relation to the literature and "analytical" yield models.Key words: Atlantic herring, growth, maturation, production
Model of Salmon Age Structure and Its Use in Preseason Forecasting and Studies of Marine Survival
Authors: Peterman Randall M.
Published: August 2008

A method is derived to determine whether ocean abundance of a salmon stock affects either the survival rate between particular ages or the proportion of the ocean population which migrates back to freshwater spawning areas. The approach, similar to Fredin's smolt indices method, uses data on brood-year contributions to adult returns in successive years. Survival rate and proportion maturing are found to be independent of stock abundance after age 3, except in Naknek River sockeye (Oncorhynchus nerka) data. In cases such as Babine Lake sockeye salmon, where nonlinearity has been identified previously in the relation between smolt abundance and total adult returns, this lack of density dependence in the older ages means that the mortality processes which cause that nonlinearity act early in smolt life. The relations between abundance of adult returns of age n in year t and returns of age n + 1 from the same brood class in year t + 1 are useful as preseason forecasting techniques. The method derived here, which uses logarithms of abundances, improves upon the existing forecasting method. Deviations from the relation between abundances of brood-year returns can in some cases be explained by smolt weight, which is shown to affect mean age at return.Key words: salmon age structure, marine survival, age-at-return, smolt weight, preseason forecasting
Influence of Hatchery Experience on Growth and Behavior of Juvenile Atlantic Salmon (Salmo salar) Within Allopatric and Sympatric Stream Populations
Authors: Dickson T. A. , MacCrimmon H. R.
Published: August 2008

Hatchery-reared Atlantic salmon (Salmo salar), wild Atlantic salmon and brook trout (Salvelinus fontinalis) (0+ year-class fish) were observed in allopatric or paired sympatric populations using stream tanks at the Matamek Research Station, Quebec. Hatchery-reared salmon maintained a position just off the substrate, a position intermediate to that occupied by wild salmon (bottom) and trout (midwater). Growth rates of hatchery-reared and wild salmon were not statistically different. Neither type had an interactive advantage. It is concluded that the behavioral pattern of hatchery-reared salmon was intermediate to that of wild salmon and trout. This behavioral shift may account for poor survival of planted Atlantic salmon juveniles, a phenomenon suggesting the need for a reexamination of present live release programs using juvenile hatchery-reared salmon.Key words: behavior, hatchery-rearing effects, growth, interspecific interactions, stream tank study, juvenile Atlantic salmon, juvenile brook trout