Showing papers by "University of Alberta published in 2002"

Verification Strategies for Establishing Reliability and Validity in Qualitative Research

Abstract: The rejection of reliability and validity in qualitative inquiry in the 1980s has resulted in an interesting shift for "ensuring rigor" from the investigator’s actions during the course of the research, to the reader or consumer of qualitative inquiry. The emphasis on strategies that are implemented during the research process has been replaced by strategies for evaluating trustworthiness and utility that are implemented once a study is completed. In this article, we argue that reliability and validity remain appropriate concepts for attaining rigor in qualitative research. We argue that qualitative researchers should reclaim responsibility for reliability and validity by implementing verification strategies integral and self-correcting during the conduct of inquiry itself. This ensures the attainment of rigor using strategies inherent within each qualitative design, and moves the responsibility for incorporating and maintaining reliability and validity from external reviewers’ judgements to the investigators themselves. Finally, we make a plea for a return to terminology for ensuring rigor that is used by mainstream science.

The basis of anisotropic water diffusion in the nervous system – a technical review

Abstract: Anisotropic water diffusion in neural fibres such as nerve, white matter in spinal cord, or white matter in brain forms the basis for the utilization of diffusion tensor imaging (DTI) to track fibre pathways. The fact that water diffusion is sensitive to the underlying tissue microstructure provides a unique method of assessing the orientation and integrity of these neural fibres, which may be useful in assessing a number of neurological disorders. The purpose of this review is to characterize the relationship of nuclear magnetic resonance measurements of water diffusion and its anisotropy (i.e. directional dependence) with the underlying microstructure of neural fibres. The emphasis of the review will be on model neurological systems both in vitro and in vivo. A systematic discussion of the possible sources of anisotropy and their evaluation will be presented followed by an overview of various studies of restricted diffusion and compartmentation as they relate to anisotropy. Pertinent pathological models, developmental studies and theoretical analyses provide further insight into the basis of anisotropic diffusion and its potential utility in the nervous system.

Theorizing Change: The Role of Professional Associations in the Transformation of Institutionalized Fields

Abstract: This study examines the role of professional associations in a changing, highly institutionalized organizational field and suggests that they play a significant role in legitimating change. A model...

Ligand-targeted therapeutics in anticancer therapy

Abstract: Cytotoxic chemotherapy or radiotherapy of cancer is limited by serious, sometimes life-threatening, side effects that arise from toxicities to sensitive normal cells because the therapies are not selective for malignant cells. So how can selectivity be improved? One strategy is to couple the therapeutics to antibodies or other ligands that recognize tumour-associated antigens. This increases the exposure of the malignant cells, and reduces the exposure of normal cells, to the ligand-targeted therapeutics.

Multiattribute and single-attribute utility functions for the health utilities index mark 3 system.

Abstract: Background.The Health Utilities Index Mark 3 (HUI3) is a generic multiattribute preference-based measure of health status and health-related quality of life that is widely used as an outcome measure in clinical studies, in population health surveys, in the estimation of quality-adjusted life years,

Understanding heterogeneous preferences in random utility models: a latent class approach.

Abstract: A finite mixture approach toconditional logit models is developed in whichlatent classes are used to promoteunderstanding of systematic heterogeneity. The model is applied to wilderness recreationin which a branded choice experiment involvingchoice of one park from a demand system wasadministered to a sample of recreationists. The basis of membership in the classes orsegments in the sample involved attitudinalmeasures of motivations for taking a trip, aswell as their stated preferences overwilderness park attributes. The econometricanalysis suggested that four classes of peopleexist in the sample. Using the model toexamine welfare measures of some hypotheticalpolicy changes identified markedly differentwelfare effects than the standard singlesegment model, and provided insight into thedifferential impact of alternative policies.

Cytotoxic T lymphocytes: all roads lead to death

Abstract: Cytotoxic T lymphocytes (CTLs) provide potent defences against virus infection and intracellular pathogens. However, CTLs have a dark side--their lytic machinery can be directed against self-tissues in autoimmune disorders, transplanted cells during graft rejection and host tissues to cause graft-versus-host disease, which is one of the most serious diseases related to CTL function. Although this duplicitous behaviour might seem contradictory, both beneficial and detrimental effects are the result of the same effector proteins. So, an understanding of the mechanisms that are used by CTLs to destroy targets and a knowledge of pathogen immune-evasion strategies will provide vital information for the design of new therapies.

An ounce of prevention or a pound of cure: bioeconomic risk analysis of invasive species

Abstract: Numbers of non-indigenous species--species introduced from elsewhere - are increasing rapidly worldwide, causing both environmental and economic damage. Rigorous quantitative risk-analysis frameworks, however, for invasive species are lacking. We need to evaluate the risks posed by invasive species and quantify the relative merits of different management strategies (e.g. allocation of resources between prevention and control). We present a quantitative bioeconomic modelling framework to analyse risks from non-indigenous species to economic activity and the environment. The model identifies the optimal allocation of resources to prevention versus control, acceptable invasion risks and consequences of invasion to optimal investments (e.g. labour and capital). We apply the model to zebra mussels (Dreissena polymorpha), and show that society could benefit by spending up to US$324 000 year(-1) to prevent invasions into a single lake with a power plant. By contrast, the US Fish and Wildlife Service spent US$825 000 in 2001 to manage all aquatic invaders in all US lakes. Thus, greater investment in prevention is warranted.

Successful islet transplantation: continued insulin reserve provides long-term glycemic control.

Abstract: Clinical islet transplantation is gaining acceptance as a potential therapy, particularly for subjects who have labile diabetes or problems with hypoglycemic awareness. The risks of the procedure and long-term outcomes are still not fully known. We have performed 54 islet transplantation procedures on 30 subjects and have detailed follow-up in 17 consecutive Edmonton protocol-treated subjects who attained insulin independence after transplantation of adequate numbers of islets. Subjects were assessed pretransplant and followed prospectively posttransplant for immediate and long-term complications related to the procedure or immunosuppressive therapy. The 17 patients all became insulin independent after a minimum of 9,000 islets/kg were transplanted. Of 15 consecutive patients with at least 1 year of follow-up after the initial transplant, 12 (80%) were insulin independent at 1 year. In 14 subjects who have maintained demonstrable C-peptide secretion, glucose control has been stable and glycemic lability and problems with hypoglycemic reactions have been corrected. After 2 of the 54 procedures, some thrombosis was detected in the portal vein circulation. Five subjects had bleeding related to the percutaneous portal vein access procedures: three required transfusion alone, and in one subject, who had a partial thrombosis of the portal vein, an expanding intrahepatic and subscapular hemorrhage occurred while on anticoagulation, requiring transfusion and surgery. Elevated liver function test results were found in 46% of subjects but resolved in all. Complications related to the therapy have been hypercholesterolemia requiring statin therapy in 65%; a rise in creatinine in two patients, both of whom had preexisting renal disease; a rise in protein in four, all of whom had preexisting proteinuria; and antihypertensive therapy increased or started in 53%. Three of the 17 patients have required retinal laser photocoagulation. There have been no cases of posttransplant lymphoproliferative disorder or cytomegalovirus infection, and no deaths. The acute insulin response to arginine correlated better with transplanted islet mass than acute insulin response to glucose (AIR g ) and area under the curve for insulin (AUC i ), but the AIR g and AUC i were more closely related to glycemic control. The AUC i directly posttransplant was lower in those who eventually became C-peptide deficient. Our results, with a maximum follow-up of 34 months, indicate that prolonged insulin independence can be achieved after islet transplantation. There are some risks associated acutely with the procedure, and hypercholesterolemia and hypertension are treatable concerns on longer-term follow-up. All patients with persisting C-peptide secretion have had a resolution of both glycemic lability and problems with hypoglycemic reactions. Apart from the rise in serum creatinine in two subjects, no serious consequences of immunosuppressive therapy have been encountered. Islet transplantation is a reasonable option in those with severe problems with glycemic lability or hypoglycemia.

The biotic ligand model : a historical overview

Abstract: During recent years, the biotic ligand model (BLM) has been proposed as a tool to evaluate quantitatively the manner in which water chemistry affects the speciation and biological availability of metals in aquatic systems. This is an important consideration because it is the bioavailability and bioreactivity of metals that control their potential to cause adverse effects. The BLM approach has gained widespread interest amongst the scientific, regulated and regulatory communities because of its potential for use in developing water quality criteria (WQC) and in performing aquatic risk assessments for metals. Specifically, the BLM does this in a way that considers the important influences of site-specific water quality. This journal issue includes papers that describe recent advances with regard to the development of the BLM approach. Here, the current status of the BLM development effort is described in the context of the longer-term history of advances in the understanding of metal interactions in the environment upon which the BLM is based. Early developments in the aquatic chemistry of metals, the physiology of aquatic organisms and aquatic toxicology are reviewed first, and the degree to which each of these disciplines influenced the development of water quality regulations is discussed. The early scientific advances that took place in each of these fields were not well coordinated, making it difficult for regulatory authorities to take full advantage of the potential utility of what had been learned. However, this has now changed, with the BLM serving as a useful interface amongst these scientific disciplines, and within the regulatory arena as well. The more recent events that have led to the present situation are reviewed, and consideration is given to some of the future needs and developments related to the BLM that are envisioned. The research results that are described in the papers found in this journal issue represent a distinct milestone in the ongoing evolution of the BLM approach and, more generally, of approaches to performing ecological assessments for metals in aquatic systems. These papers also establish a benchmark to which future scientific and regulatory developments can be compared. Finally, they demonstrate the importance and usefulness of the concept of bioavailability and of evaluative tools such as the BLM.

Discovering word senses from text

Abstract: Inventories of manually compiled dictionaries usually serve as a source for word senses. However, they often include many rare senses while missing corpus/domain-specific senses. We present a clustering algorithm called CBC (Clustering By Committee) that automatically discovers word senses from text. It initially discovers a set of tight clusters called committees that are well scattered in the similarity space. The centroid of the members of a committee is used as the feature vector of the cluster. We proceed by assigning words to their most similar clusters. After assigning an element to a cluster, we remove their overlapping features from the element. This allows CBC to discover the less frequent senses of a word and to avoid discovering duplicate senses. Each cluster that a word belongs to represents one of its senses. We also present an evaluation methodology for automatically measuring the precision and recall of discovered senses.

Ingredients for change: revisiting a conceptual framework

Abstract: Finding ways to deliver care based on the best possible evidence remains an ongoing challenge. Further theoretical developments of a conceptual framework are presented which influence the uptake of evidence into practice. A concept analysis has been conducted on the key elements of the framework—evidence, context, and facilitation—leading to refinement of the framework. While these three essential elements remain key to the process of implementation, changes have been made to their constituent sub-elements, enabling the detail of the framework to be revised. The concept analysis has shown that the relationship between the elements and sub-elements and their relative importance need to be better understood when implementing evidence based practice. Increased understanding of these relationships would help staff to plan more effective change strategies. Anecdotal reports suggest that the framework has a good level of validity. It is planned to develop it into a practical tool to aid those involved in planning, implementing, and evaluating the impact of changes in health care.

Optimal Reliability Modeling: Principles and Applications

Abstract: PrefaceAcknowledgments1 Introduction11 Needs for Reliability Modeling12 Optimal Design2 Reliability Mathematics21 Probability and Distributions211 Events and Boolean Algebra212 Probabilities of Events213 Random Variables and Their Characteristics214 Multivariate Distributions215 Special Discrete Distributions216 Special Continuous Distributions22 Reliability Concepts23 Commonly Used Lifetime Distributions24 Stochastic Processes241 General Definitions242 Homogeneous Poisson Process243 Nonhomogeneous Poisson Process244 Renewal Process245 Discrete-Time Markov Chains246 Continuous-Time Markov Chains25 Complex System Reliability Assessment Using Fault Tree Analysis3 Complexity Analysis31 Orders of Magnitude and Growth32 Evaluation of Summations33 Bounding Summations34 Recurrence Relations341 Expansion Method342 Guess-and-Prove Method343 Master Method35 Summary4 Fundamental System Reliability Models41 Reliability Block Diagram42 Structure Functions43 Coherent Systems44 Minimal Paths and Minimal Cuts45 Logic Functions46 Modules within a Coherent System47 Measures of Performance48 One-Component System49 Series System Model491 System Reliability Function and MTTF492 System Availability410 Parallel System Model4101 System Reliability Function and MTTF4102 System Availability of Parallel System with Two iid Components4103 System Availability of Parallel System with Two Different Components4104 Parallel Systems with n iid Components411 Parallel-Series System Model412 Series-Parallel System Model413 Standby System Model4131 Cold Standby Systems4132 Warm Standby Systems5 General Methods for System Reliability Evaluation51 Parallel and Series Reductions52 Pivotal Decomposition53 Generation of Minimal Paths and Minimal Cuts531 Connection Matrix532 Node Removal Method for Generation of Minimal Paths533 Generation of Minimal Cuts from Minimal Paths54 Inclusion-Exclusion Method55 Sum-of-Disjoint-Products Method56 Markov Chain Imbeddable Structures561 MIS Technique in Terms of System Failures562 MIS Technique in Terms of System Success57 Delta-Star and Star-Delta Transformations571 Star or Delta Structure with One Input Node and Two Output Nodes572 Delta Structure in Which Each Node May Be either an Input Node or an Output Node58 Bounds on System Reliability581 IE Method582 SDP Method583 Esary-Proschan (EP) Method584 Min-Max Bounds585 Modular Decompositions586 Notes6 General Methodology for System Design61 Redundancy in System Design62 Measures of Component Importance621 Structural Importance622 Reliability Importance623 Criticality Importance624 Relative Criticality63 Majorization and Its Application in Reliability631 Definition of Majorization632 Schur Functions633 L-Additive Functions64 Reliability Importance in Optimal Design65 Pairwise Rearrangement in Optimal Design66 Optimal Arrangement for Series and Parallel Systems67 Optimal Arrangement for Series-Parallel Systems68 Optimal Arrangement for Parallel-Series Systems69 Two-Stage Systems610 Summary7 Thek-out-of-n System Model71 System Reliability Evaluation711 The k-out-of-n:G System with iid Components712 The k-out-of-n:G System with Independent Components713 Bounds on System Reliability72 Relationship between k-out-of-n G and F Systems721 Equivalence between k-out-of-n:G and (n - k + 1)-out-of-n:F Systems722 Dual Relationship between k-out-of-n G and F Systems73 Nonrepairable k-out-of-n Systems731 Systems with iid Components732 Systems with Nonidentical Components733 Systems with Load-Sharing Components Following Exponential Lifetime Distributions734 Systems with Load-Sharing Components Following Arbitrary Lifetime Distributions735 Systems with Standby Components74 Repairable k-out-of-n Systems741 General Repairable System Model742 Systems with Active Redundant Components743 Systems with Load-Sharing Components744 Systems with both Active Redundant and Cold Standby Components75 Weighted k-out-of-n:G Systems8 Design of k-out-of-n Systems81 Properties of k-out-of-n Systems811 Component Reliability Importance812 Effects of Redundancy in k-out-of-n Systems82 Optimal Design of k-out-of-n Systems821 Optimal System Size n822 Simultaneous Determination of n and k823 Optimal Replacement Time83 Fault Coverage831 Deterministic Analysis832 Stochastic Analysis84 Common-Cause Failures841 Repairable System with Lethal Common-Cause Failures842 System Design Considering Lethal Common-Cause Failures843 Optimal Replacement Policy with Lethal Common-Cause Failures844 Nonlethal Common-Cause Failures85 Dual Failure Modes851 Optimal k or n Value to Maximize System Reliability852 Optimal k or n Value to Maximize System Profit853 Optimal k and n Values to Minimize System Cost86 Other Issues861 Selective Replacement Optimization862 TMR and NMR Structures863 Installation Time of Repaired Components864 Combinations of Factors865 Partial Ordering9 Consecutive-k-out-of-n Systems91 System Reliability Evaluation911 Systems with iid Components912 Systems with Independent Components92 Optimal System Design921 B-Importances of Components922 Invariant Optimal Design923 Variant Optimal Design93 Consecutive-k-out-of-n:G Systems931 System Reliability Evaluation932 Component Reliability Importance933 Invariant Optimal Design934 Variant Optimal Design94 System Lifetime Distribution941 Systems with iid Components942 System with Exchangeable Dependent Components943 System with (k - 1)-Step Markov-Dependent Components944 Repairable Consecutive-k-out-of-n Systems95 Summary10 Multidimensional Consecutive-k-out-of-n Systems101 System Reliability Evaluation1011 Special Multidimensional Systems1012 General Two-Dimensional Systems1013 Bounds and Approximations102 System Logic Functions103 Optimal System Design104 Summary11 Other k-out-of-n and Consecutive-k-out-of-n Models111 The s-Stage k-out-of-n Systems112 Redundant Consecutive-k-out-of-n Systems113 Linear and Circular m-Consecutive-k-out-of-n Model114 The k-within-Consecutive-m-out-of-n Systems1141 Systems with iid Components1142 Systems with Independent Components1143 The k-within-(r, s)/(m, n):F Systems115 Series Consecutive-k-out-of-n Systems116 Combined k-out-of-n:F and Consecutive-kc-out-of-n:F System117 Combined k-out-of-mn:F and Linear (r, s)/(m, n):F System118 Combined k-out-of-mn:F, One-Dimensional Con/kc/n:F, and Two-Dimensional Linear (r, s)/(m, n):F Model119 Application of Combined k-out-of-n and Consecutive-k-out-of-n Systems1110 Consecutively Connected Systems1111 Weighted Consecutive-k-out-of-n Systems11111 Weighted Linear Consecutive-k-out-of-n:F Systems11112 Weighted Circular Consecutive-k-out-of-n:F Systems12 Multistate System Models121 Consecutively Connected Systems with Binary System State and Multistate Components1211 Linear Multistate Consecutively Connected Systems1212 Circular Multistate Consecutively Connected Systems1213 Tree-Structured Consecutively Connected Systems122 Two-Way Consecutively Connected Systems123 Key Concepts in Multistate Reliability Theory124 Special Multistate Systems and Their Performance Evaluation1241 Simple Multistate k-out-of-n:G Model1242 Generalized Multistate k-out-of-n:G Model1243 Generalized Multistate Consecutive-k-out-of-n:F System125 General Multistate Systems and Their Performance Evaluation126 SummaryAppendix: Laplace TransformReferencesBibliographyIndex

A balanced view of scale in spatial statistical analysis

Abstract: Concepts of spatial scale, such as extent, grain, resolution, range, footprint, support and cartographic ratio are not interchangeable. Because of the potential confusion among the definitions of these terms, we suggest that authors avoid the term "scale" and instead refer to specific concepts. In particular, we are careful to discriminate between observation scales, scales of ecological phenomena and scales used in spatial statistical analysis. When scales of observation or analysis change, that is, when the unit size, shape, spacing or extent are altered, statistical results are expected to change. The kinds of results that may change include estimates of the population mean and variance, the strength and character of spatial autocorrelation and spatial anisotropy, patch and gap sizes and multivariate relationships, The First three of these results (precision of the mean, variance and spatial autocorrelation) can sometimes be estimated using geostatistical support-effect models. We present four case studies of organism abundance and cover illustrating some of these changes and how conclusions about ecological phenomena (process and structure) may be affected. We identify the influence of observational scale on statistical results as a subset of what geographers call the Modifiable Area Unit Problem (MAUP). The way to avoid the MAUP is by careful construction of sampling design and analysis. We recommend a set of considerations for sampling design to allow useful tests for specific scales of a phenomenon under study. We further recommend that ecological studies completely report all components of observation and analysis scales to increase the possibility of cross-study comparisons.

Considerations for use of the Hoffmann reflex in exercise studies.

Abstract: There continues to be great interest in evaluating the adaptive plasticity of the human nervous system in response to exercise training or other interventions. For various reasons, researchers have been interested in estimates of spinal reflex processing in intact human subjects before and after training. A reflex pathway that has been employed in this regard is the Hoffmann (H) reflex. This brief review describes the basic procedure for evoking the H reflex in different muscles. Other sections address methodological issues that affect interpretation of the H reflex. In particular, the role that presynaptic inhibition serves in the modification of the H reflex and how this precludes its use as an unambiguous measure of alpha-motoneuron excitability will be discussed. Applications of the H reflex to study adaptive plasticity in humans is also reviewed, and methodological requirements that should be maintained for accurate interpretation of H reflexes in exercise studies are presented.

Oral Sildenafil Is an Effective and Specific Pulmonary Vasodilator in Patients With Pulmonary Arterial Hypertension Comparison With Inhaled Nitric Oxide

Abstract: Background — The prognosis of patients with severe pulmonary hypertension (PHT) is poor. To determine prognosis and guide therapy, an acute hemodynamic trial of selective pulmonary vasodilators, usually inhaled nitric oxide (iNO), was performed. We hypothesized that oral sildenafil, a phosphodiesterase-5 inhibitor, is a safe and effective alternative to iNO. Methods and Results — We studied 13 consecutive patients (mean±SEM, 44±2 years of age; 9 women) referred for consideration of heart-lung transplantation or as a guide to medical therapy. All but one were functional class III or IV. Patients had primary PHT (n=9), pulmonary arterial hypertension (n=2), or secondary PHT (n=2). Hemodynamics and serum cyclic guanosine-monophosphate levels (cGMP) were measured at baseline and at peak effects of iNO (80 ppm), sildenafil (75 mg), and their combination. The decrease in pulmonary vascular resistance was similar with iNO (−19±5%) and sildenafil (−27±3%), whereas sildenafil+iNO was more effective than iNO alone (−32±5%, P P P P Conclusions — A single oral dose of sildenafil is as effective and selective a pulmonary vasodilator as iNO. Sildenafil may be superior to iNO in that it increases cardiac output and does not increase wedge pressure. Future studies are indicated to establish whether sildenafil could be effective over a longer duration.

A controlled trial of rasagiline in early Parkinson disease: The tempo study

Abstract: CONTEXT Monotherapy with rasagiline mesylate may be useful in early Parkinson disease (PD). OBJECTIVE To evaluate the safety and efficacy of the selective monoamine oxidase type B inhibitor rasagiline. DESIGN Multicenter, 26-week, parallel-group, randomized, double-blind, placebo-controlled clinical trial. SETTING Academically based movement disorders clinics. PATIENTS Patients with early PD not requiring dopaminergic therapy (n = 404). INTERVENTION Research participants were randomized to rasagiline mesylate at dosages of 1 mg or 2 mg per day or matching placebo. A 1-week escalation period was followed by a 25-week maintenance period. MAIN OUTCOME MEASURE The primary prespecified measure of efficacy was the change in the total Unified Parkinson's Disease Rating Scal score between baseline and 26 weeks of treatment, comparing each active treatment group with the placebo group. RESULTS Monotherapy with rasagiline was effective in this 26-week study. The adjusted effect size for the total Unified Parkinson's Disease Rating Scale was -4.20 units comparing 1 mg of rasagiline and placebo (95% confidence interval, -5.66 to -2.73 units; P<.001) and -3.56 units comparing a 2-mg dosage and placebo (95% confidence interval, -5.04 to -2.08 units; P<.001). There were no meaningful differences in the frequency of adverse events or premature withdrawals among the treatment groups. CONCLUSIONS Rasagiline is effective as monotherapy for patients with early PD. The 2 dosages in this trial were both effective relative to placebo. Further study is warranted to evaluate the longer-term effects of rasagiline in PD.

Nucleoside analogues and nucleobases in cancer treatment.

Abstract: Cytotoxic nucleoside analogues and nucleobases were among the first chemotherapeutic agents to be introduced for the medical treatment of cancer. This family of compounds has grown to include a variety of purine and pyrimidine nucleoside derivatives with activity in both solid tumours and malignant disorders of the blood. These agents behave as antimetabolites, compete with physiological nucleosides, and interact with a large number of intracellular targets to induce cytotoxicity. Progress has recently been made in the identification and characterisation of nucleoside transporters and the enzymes of nucleoside metabolism. In addition, there is now greater understanding of the molecular mechanisms of anticancer nucleoside activity, which provides opportunities for potentiating their antitumour effects. Strategies to optimise intracellular analogue accumulation and to enhance cancer-cell selectivity are proving beneficial in clinical trials.

Measuring Reform Practices in Science and Mathematics Classrooms: The Reformed Teaching Observation Protocol

Abstract: The National Science Foundation has funded 22 Collaboratives for Excellence in Teacher Preparation. Despite the remarkable allocation of resources to this effort, it has proven exceptionally difficult to demonstrate the effectiveness of collaborative reform. In large part, this has resulted because of the difficulty of defining and measuring reform. The Reformed Teaching Observation Protocol (RTOP) was designed by the Evaluation Facilitation Group of the Arizona Collaborative for Excellence in the Preparation of Teachers (ACEPT). It is a 25-item classroom observation protocol that is (a) standards based, (b) inquiry oriented, and (c) student centered. This instrument has provided the definition for reform and the basis for evaluation of the ACEPT collaborative. The data upon which this report is based were collected over a period of more than 2 years from 153 public school, college, and university mathematics and science classrooms. A trained team of observers consisting of two faculty members and seven graduate students was able to achieve exceptionally high levels of interrater reliability. Internal consistency, as estimated by Cronbach's alpha, was also remarkably high. Correlation coefficients ranging from 0.88 to 0.97 between RTOP scores for classrooms, and mean normalized gain scores for students in those classrooms on achievement measures demonstrate that reform, as defined by ACEPT and measured by the RTOP, has been effective.

Could bacteria have formed the Precambrian banded iron formations

Abstract: Banded iron formations (BIFs) are prominent sedimentary deposits of the Precambrian, but despite a century of endeavor, the mechanisms of their deposition are still unresolved. Interactions between microorganisms and dissolved ferrous iron in the ancient oceans offer one plausible means of mineral precipitation, in which bacteria directly generate ferric iron either by chemolithoautotrophic iron oxidation or by photoferrotrophy. On the basis of chemical analyses from BIF units of the 2.5 Ga Hamersley Group, Western Australia, we show here that even during periods of maximum iron precipitation, most, if not all, of the iron in BIFs could be precipitated by iron-oxidizing bacteria in cell densities considerably less than those found in modern Fe-rich aqueous environments. Those ancient microorganisms would also have been easily supported by the concentrations of nutrients (P) and trace metals (V, Mn, Co, Zn, and Mo) found within the same iron-rich bands. These calculations highlight the potential importance of early microbial activity on ancient metal cycling.