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The idea of clustering students according to their online learning behavior has the potential of providing more adaptive scaffolding by the intelligent tutoring system itself or by a human teacher. With the aim of identifying student groups who would benefit from the same intervention in AC-ware Tutor, this research examined online learning behavior using 8 tracking variables: the total number of content pages seen in the learning process; the total number of concepts; the total online score; the total time spent online; the total number of logins; the stereotype after the initial test, the final stereotype, and the mean stereotype variability. The previous measures were used in a four-step analysis that consisted of data preprocessing, dimensionality reduction, the clustering, and the analysis of a posttest performance on a content proficiency exam. The results were also used to construct the decision tree in order to get a human-readable description of student clusters.

PurposePatients who undergo surgery for papillary thyroid cancer with only a limited lymph node examination are thought to be at risk for potentially harboring occult disease. However, this risk has not been objectively quantified and may have implications for subsequent management and surveillance.MethodsData from the National Cancer Database (1998 to 2012) were used to characterize the distribution of nodal positivity of adult patients diagnosed with localized ≥ 1-cm papillary thyroid cancer who underwent thyroidectomy with one or more lymph nodes (LNs) examined. A β-binomial distribution was used to estimate the probability of occult nodal disease as a function of total number of LNs examined and pathologic tumor stage.ResultsA total of 78,724 patients met study criteria; 38,653 patients had node-positive disease. The probability of falsely identifying a patient as node negative was estimated to be 53% for patients with a single node examined and decreased to less than 10% when more than six LNs were examined. To rule out occult nodal disease with 90% confidence, six, nine, and 18 nodes would need to be examined for patients with T1b, T2, and T3 disease, respectively. Sensitivity analyses limited to patients likely undergoing prophylactic central neck dissection resulted in three, four, and eight nodes needed to provide comparable adequacy of LN evaluation.ConclusionTo our knowledge, our study provides the first empirically based estimates of occult nodal disease risk in patients after surgery for papillary thyroid cancer as a function of primary tumor stage and number of LNs examined. Our estimates provide an objective guideline for evaluating adequacy of LN yield for surgeons and pathologists in the treatment of papillary thyroid cancer, and especially intermediate-risk disease, for which use of adjuvant radioactive iodine and surveillance intensity are not currently standardized.

Natural gas extraction is a critical driver of the economy in western North America. Ecological reclamation is important to ensure surface disturbance impacts associated with natural gas development are not permanent and to assist native biota. Previous studies in semi-arid natural gas fields within Sublette County, Wyoming, USA have shown insects respond favorably to 1–3-year-old well pads undergoing reclamation compared to older successional reference vegetation communities dominated by Wyoming big sagebrush (Artemisia tridentata spp. Wyomingensis). Here, we examined well pads which were initially seed 5, 8, 10, 11, and 12 years prior to our study. We used a free, image-based software called SamplePointv. 1.60 to quantify vegetation on these well pads and adjacent reference areas from cell phone camera photographs. Insects were collected with a sweep net and identified to the family and morphospecies level. Statistical analyses were conducted to compare both vegetation and insect communities between reclamation sites and their paired reference area. We found little statistical difference between vegetation communities across our study but found significantly more insect abundance on reclaimed well pads than reference areas in 3 of 5 years and significantly higher family and morphospecies richness on reclaimed well pads in 4 of 5 years. A total of 2036 individual insects representing 270 species from 71 families across 11 orders were identified across this study. A total of 1557 individuals (76.5%) were found on reclamation sites, whereas 479 (23.5%) were found in reference areas across the entire study. A total of 233 species (86.3% of total) were found on reclamation sites, whereas 121 species (44.8% of total) were found in reference areas across the entire study. A total of 67 families (94.4% of total) were found on reclamation sites, whereas 45 families (63.4% of total) were found in reference areas across the entire study. All 11 orders found in the study were found on reclamation sites, whereas 9 orders were found in reference areas across the entire study. Our results suggest reclamation of natural gas well pads within an old successional stand of sagebrush continues to support higher levels of insect biodiversity and abundance for at least 12 years. As insects are the most diverse group of animals on Earth and because they provide a wide array of ecosystem services, our findings suggest ecological reclamation plays an important role in returning biodiversity and ecosystem functionality to a semi-arid and old successional sagebrush–steppe ecosystem. [ABSTRACT FROM AUTHOR]

Patients with primary central nervous system lymphoma (PCNSL) typically present with non-focal neurological symptoms, including disorientation, poor balance and memory loss with unifocal or multifocal periventricular lesions seen on MRI. Deviations from these characteristic findings can delay diagnosis and lead to additional diagnostic tests being needed. The present study reports a 68-year-old man with a recent varicella zoster infection and history of acetylcholine receptor antibody-positive myasthenia gravis who received mycophenolate mofetil for 22 years. He presented with left eye vision changes and cognitive memory deficits. A brain MRI showed an enhancing lesion within his left medulla extending to the cerebellum. Cerebrospinal fluid analysis was positive for Epstein-Barr virus (EBV) and negative for malignancy. He was diagnosed with varicella zoster virus vasculopathy. At 3 months later, a repeat brain MRI showed multiple new enhancing lesions developing bilaterally along the periventricular white matter. Soon after, he presented to a local ER with acute left-sided blurry vision and worsening memory loss, and he began receiving steroids. Because of rapid symptom progression, he underwent resection of the left frontal lesion, which showed EBV-induced diffuse large B-cell lymphoma (DLBCL). Mycophenolate mofetil was discontinued, and within 24 h of one dose of intravenous 500 mg/m2 rituximab, he had a dramatic improvement in left eye vision and memory loss. He experienced mixed responses to rituximab after 3 cycles. Following one dose of high-dose methotrexate, he developed subsequent chronic kidney disease and required dialysis. He received whole-brain radiation therapy with craniospinal radiation and is currently in complete remission. An EBV-induced DLBCL diagnosis should be highly considered for patients with periventricular lesions and EBV-positive cerebrospinal fluid. Misdiagnosis or delay in PCNSL diagnosis because of atypical features in disease presentation and radiographic findings could lead to PCNSL progression and worsening neurological deficits. [ABSTRACT FROM AUTHOR]

Animals are inherently tied to nutritional resources of the landscape. Added cost of coping with environmental stressors, like disease, can exacerbate nutritional limitations. Pneumonia, a respiratory disease caused primarily by bacterial pathogens, has caused massive declines in populations of bighorn sheep (Ovis canadensis) throughout western North America. Nevertheless, population dynamics following a pneumonia epizootic vary across populations, which has spawned the idea that ecological conditions may play a role in regulating populations after a die‐off. We used 2 bighorn sheep populations with contrasting dynamics to test the hypothesis that habitat quality on summer range affects population dynamics following a pneumonia epizootic. We sampled over 700 vegetation transects and quantified nutrient content of 2,093 forage samples of 127 genera on summer ranges to compare habitat quality (macro‐ and micronutrients in forage, biomass, plant cover, and species diversity) between the ranges. The population exhibiting growth, higher recruitment, and better nutritional condition had over double the herbaceous biomass in their core foraging areas in summer than the population exhibiting decline, lower recruitment, and poorer nutritional status. The population experiencing growth also had more macro‐ and micronutrients available on their summer range as a function of higher biomass along with higher species diversity. Although winter range often is considered the nutritional bottleneck for ungulates, we demonstrate that the conditions of summer range can have consequences for population dynamics. Habitat quality should be incorporated when considering management objectives and population recovery of large herbivores in the presence of disease; interactions between habitat quality and population dynamics still apply and likely are amplified with additional stressors like disease. [ABSTRACT FROM AUTHOR]

Bayesian methodology continues to be widely used in statistical applications. As a result, it is increasingly important to introduce students to Bayesian thinking at early stages in their mathematics and statistics education. While many students in upper level probability courses can recite the differences in the Frequentist and Bayesian inferential paradigms, these students often struggle using Bayesian methods when conducting data analysis. Specifically, students tend to struggle translating subjective belief to the specification of a prior distribution and the incorporation of uncertainty in the Bayesian inferential approach. The purpose of this paper is to present a hands-on activity involving the Beta-Binomial model to facilitate an intuitive understanding of the Bayesian approach through subjective problem formulation which lies at the heart of Bayesian statistics.

Introduction: High-dose total body irradiation (TBI) is often part of myeloablative conditioning in acute leukemia. Modern volumetric modulated arc therapy (VMAT)-based plans employ arcs to the inferior-most portion of the body that can be simulated in a head-first position and use 2D planning for the inferior body which can result in heterogeneous doses. Here, we describe our institution's unique protocol for delivering high-dose TBI entirely with VMAT and retrospectively compare dosimetric outcomes with helical tomotherapy (HT) plans. Additionally, we describe our method of oropharyngeal mucosal sparing that was implemented after fatal mucositis occurred in two patients. Methods: Thirty-one patients were simulated and treated in head-first (HFS) and feet-first (FFS) orientations. Patients were treated with VMAT (n = 26) or HT (n = 5). In VMAT plans, to synchronize doses between the orientations, images were deformably registered and the HFS dose was transferred to the FFS plan and used as a background dose when optimizing plans. Six to eight isocenters with two arcs per isocenter were generated. HT was delivered with an established technique. Patients were treated to 13.2 Gy over eight twice daily fractions. Dosimetric outcomes and toxicities were retrospectively compared. Results: Prescription dose and organ at risk (OAR) constraints were met for all patients. Lower lung doses were achieved with VMAT relative to HT plans (7.4 vs 7.7 Gy, P =.009). Statistically significant improvement in mucositis was not achieved after adopting a mucosal-sparing technique, however lower doses to the oropharyngeal mucosal were achieved (6.9 vs 14.1 Gy, P =.009), and no further mucositis-related deaths occurred. Conclusions: This full-body VMAT method of TBI achieves dose goals, eliminates risk of heterogenous doses within the femur, and demonstrates that selective OAR sparing with the purpose of reducing TBI-related morbidity and mortality is possible at any institution with a VMAT-capable linear accelerator. [ABSTRACT FROM AUTHOR]

While split-plot designs have received considerable attention in the literature over the past decade, there seems to be a general lack of intuitive understanding of the error structure of these designs and the resulting statistical analysis. Typically, students learn the proper error terms for testing factors of a split-plot design via "expected mean squares". This does not provide any true insight as far as why a particular error term is appropriate for a given factor effect. We provide a way to intuitively understand the error structure and resulting statistical analysis in split-plot designs through building on concepts found in simple designs, such as completely randomized and randomized complete block designs, and then provide a way for students to "see" the error structure graphically. The discussion is couched around an example from paper manufacturing. (Contains 9 tables and 3 figures.)