A latent trait look at pretest-posttest validation of criterion-referenced test items

Since Cox and Vargas (1966) introduced their pretest-posttest validity index for criterion-referenced test items, a great number of additions and modifications have followed. All are based on the idea of gain scoring; that is, they are computed from the differences between proportions of pretest and posttest item responses. Although the method is simple and generally considered as the prototype of criterion-referenced item analysis, it has many and serious disadvantages. Some of these go back to the fact that it leads to indices based on a dual test administration- and population-dependent item p values. Others have to do with the global information about the discriminating power that these indices provide, the implicit weighting they suppose, and the meaningless maximization of posttest scores they lead to. Analyzing the pretest-posttest method from a latent trait point of view, it is proposed to replace indices like Cox and Vargas’ Dpp by an evaluation of the item information function for the mastery score. An empirical study was conducted to compare the differences in item selection between both methods

Neuromuscular Blockade with Rocuronium Bromide Increases the Tolerance of Acute Normovolemic Anemia in Anesthetized Pigs

Background: The patient's individual anemia tolerance is pivotal when blood transfusions become necessary, but are not feasible for some reason. To date, the effects of neuromuscular blockade (NMB) on anemia tolerance have not been investigated. Methods: 14 anesthetized and mechanically ventilated pigs were randomly assigned to the Roc group (3.78 mg/kg rocuronium bromide followed by continuous infusion of 1 mg/kg/min, n = 7) or to the Sal group (administration of the corresponding volume of normal saline, n = 7). Subsequently, acute normovolemic anemia was induced by simultaneous exchange of whole blood for a 6% hydroxyethyl starch solution (130/0.4) until a sudden decrease of total body O-2 consumption (VO2) indicated a critical limitation of O-2 transport capacity. The Hb concentration quantified at this time point (Hb(crit)) was the primary end-point of the protocol. Secondary endpoints were parameters of hemodynamics, O-2 transport and tissue oxygenation. Results: Hb(crit) was significantly lower in the Roc group (2.4 +/- 0.5 vs. 3.2 +/- 0.7 g/dl) reflecting increased anemia tolerance. NMB with rocuronium bromide reduced skeletal muscular VO2 and total body O-2 extraction rate. As the cardiac index increased simultaneously, total body VO2 only decreased marginally in the Roc group (change of VO2 relative to baseline -1.7 +/- 0.8 vs. 3.2 +/- 1.9% in the Sal group, p < 0.05). Conclusion: Deep NMB with rocuronium bromide increases the tolerance of acute normovolemic anemia. The underlying mechanism most likely involves a reduction of skeletal muscular VO2. During acellular treatment of an acute blood loss, NMB might play an adjuvant role in situations where profound stages of normovolemic anemia have to be tolerated (e.g. bridging an unexpected blood loss until blood products become available for transfusion). Copyright (C) 2011 S. Karger AG, Base

Cardiovascular dynamics in ischemic cardiomyopathy during exercise

Cardiac Dysfunction and Arrhythmia

High resolution mapping of a novel late blight resistance gene Rpi-avll, from the wild Bolivian species Solanum avilesii

Both Mexico and South America are rich in Solanum species that might be valuable sources of resistance (R) genes to late blight (Phytophthora infestans). Here, we focus on an R gene present in the diploid Bolivian species S. avilesii. The genotype carrying the R gene was resistant to eight out of 10 Phytophthora isolates of various provenances. The identification of a resistant phenotype and the generation of a segregating population allowed the mapping of a single dominant R gene, Rpi-avl1, which is located in an R gene cluster on chromosome 11. This R gene cluster is considered as an R gene “hot spot”, containing R genes to at least five different pathogens. High resolution mapping of the Rpi-avl1 gene revealed a marker co-segregating in 3890 F1 individuals, which may be used for marker assisted selection in breeding programs and for further cloning of Rpi-avl

Experimental effects of climate messages vary geographically

Social science scholars routinely evaluate the efficacy of diverse climate frames using local convenience or nationally representative samples. For example, previous research has focused on communicating the scientific consensus on climate change, which has been identified as a ‘gateway’ cognition to other key beliefs about the issue6,7,8,9. Importantly, although these efforts reveal average public responsiveness to particular climate frames, they do not describe variation in message effectiveness at the spatial and political scales relevant for climate policymaking. Here we use a small-area estimation method to map geographical variation in public responsiveness to information about the scientific consensus as part of a large-scale randomized national experiment (n = 6,301). Our survey experiment finds that, on average, public perception of the consensus increases by 16 percentage points after message exposure. However, substantial spatial variation exists across the United States at state and local scales. Crucially, responsiveness is highest in more conservative parts of the country, leading to national convergence in perceptions of the climate science consensus across diverse political geographies. These findings not only advance a geographical understanding of how the public engages with information about scientific agreement, but will also prove useful for policymakers, practitioners and scientists engaged in climate change mitigation and adaptation.MacArhur Foundation, Energy Foundatio

Are physical symptoms among survivors of a disaster presented to the general practitioner? A comparison between self-reports and GP data

<p>Abstract</p> <p>Background</p> <p>Most studies examining medically unexplained symptoms (MUS) have been performed in primary or secondary care and have examined symptoms for which patients sought medical attention. Disasters are often described as precipitating factors for MUS. However, health consequences of disasters are typically measured by means of questionnaires, and it is not known whether these self-reported physical symptoms are presented to the GP. It is also not known if the self-reported symptoms are related to a medical disorder or if they remain medically unexplained. In the present study, three research questions were addressed. Firstly, were self-reported symptoms among survivors presented to the GP? Secondly, were the symptoms presented to the GP associated with a high level of functional impairment and distress? Thirdly, what was the GP's clinical judgment of the presented symptoms, i.e. were the symptoms related to a medical diagnosis or could they be labeled MUS?</p> <p>Methods</p> <p>Survivors of a man-made disaster (N = 887) completed a questionnaire 3 weeks (T1) and 18 months (T2) post-disaster. This longitudinal health survey was combined with an ongoing surveillance program of health problems registered by GPs.</p> <p>Results</p> <p>The majority of self-reported symptoms was not presented to the GP and survivors were most likely to present persistent symptoms to the GP. For example, survivors with stomachache at both T1 and T2 were more likely to report stomachache to their GP (28%) than survivors with stomachache at only T1 (6%) or only T2 (13%). Presentation of individual symptoms to the GP was not consistently associated with functional impairment and distress. 56 – 91% of symptoms were labeled as MUS after clinical examination.</p> <p>Conclusion</p> <p>These results indicate that the majority of self-reported symptoms among survivors of a disaster are not presented to the GP and that the decision to consult with a GP for an individual symptom is not dependent on the level of impairment and distress. Also, self-reported physical symptoms such as headache, back pain and shortness of breath are likely to remain medically unexplained after the clinical judgment of a GP.</p

SUBMIT: Systemic therapy with or without up front surgery of the primary tumor in breast cancer patients with distant metastases at initial presentation

<p>Abstract</p> <p>Background</p> <p>Five percent of all patients with breast cancer have distant metastatic disease at initial presentation. Because metastatic breast cancer is considered to be an incurable disease, it is generally treated with a palliative intent. Recent non-randomized studies have demonstrated that (complete) resection of the primary tumor is associated with a significant improvement of the survival of patients with primary metastatic breast cancer. However, other studies have suggested that the claimed survival benefit by surgery may be caused by selection bias. Therefore, a randomized controlled trial will be performed to assess whether breast surgery in patients with primary distant metastatic breast cancer will improve the prognosis.</p> <p>Design</p> <p>Randomization will take place after the diagnosis of primary distant metastatic breast cancer. Patients will either be randomized to up front surgery of the breast tumor followed by systemic therapy or to systemic therapy, followed by delayed local treatment of the breast tumor if clinically indicated.</p> <p>Patients with primary distant metastatic breast cancer, with no prior treatment of the breast cancer, who are 18 years or older and fit enough to undergo surgery and systemic therapy are eligible. Important exclusion criteria are: prior invasive breast cancer, surgical treatment or radiotherapy of this breast tumor before randomization, irresectable T4 tumor and synchronous bilateral breast cancer. The primary endpoint is 2-year survival. Quality of life and local tumor control are among the secondary endpoints.</p> <p>Based on the results of prior research it was calculated that 258 patients are needed in each treatment arm, assuming a power of 80%. Total accrual time is expected to take 60 months. An interim analysis will be performed to assess any clinically significant safety concerns and to determine whether there is evidence that up front surgery is clinically or statistically inferior to systemic therapy with respect to the primary endpoint.</p> <p>Discussion</p> <p>The SUBMIT study is a randomized controlled trial that will provide evidence on whether or not surgery of the primary tumor in breast cancer patients with metastatic disease at initial presentation results in an improved survival.</p> <p>Trial registration</p> <p><a href="http://www.clinicaltrials.gov/ct2/show/NCT01392586">NCT01392586</a>.</p

Functional Connectivity fMRI of the Rodent Brain: Comparison of Functional Connectivity Networks in Rat and Mouse

At present, resting state functional MRI (rsfMRI) is increasingly used in human neuropathological research. The present study aims at implementing rsfMRI in mice, a species that holds the widest variety of neurological disease models. Moreover, by acquiring rsfMRI data with a comparable protocol for anesthesia, scanning and analysis, in both rats and mice we were able to compare findings obtained in both species. The outcome of rsfMRI is different for rats and mice and depends strongly on the applied number of components in the Independent Component Analysis (ICA). The most important difference was the appearance of unilateral cortical components for the mouse resting state data compared to bilateral rat cortical networks. Furthermore, a higher number of components was needed for the ICA analysis to separate different cortical regions in mice as compared to rats

Identification strategy for unknown pollutants using high-resolution mass spectrometry: Androgen-disrupting compounds identified through effect-directed analysis

Effect-directed analysis has been applied to a river sediment sample of concern to identify the compounds responsible for the observed effects in an in vitro (anti-)androgenicity assay. For identification after non-target analysis performed on a high-resolution LTQ-Orbitrap, we developed a de novo identification strategy including physico-chemical parameters derived from the effect-directed analysis approach. With this identification strategy, we were able to handle the immense amount of data produced by non-target accurate mass analysis. The effect-directed analysis approach, together with the identification strategy, led to the successful identification of eight androgen-disrupting compounds belonging to very diverse compound classes: an oxygenated polyaromatic hydrocarbon, organophosphates, musks, and steroids. This is one of the first studies in the field of environmental analysis dealing with the difficult task of handling the large amount of data produced from non-target analysis. The combination of bioassay activity assessment, accurate mass measurement, and the identification and confirmation strategy is a promising approach for future identification of environmental key toxicants that are not included as priority pollutants in monitoring programs