Fisher's microscope and Haldane's ellipse

Fisher’s geometrical model was introduced to study the phenotypic size of mutations contributing to adaptation. However, as pointed out by Haldane, the model involves a simplified picture of the action of natural selection, and this calls into question its generality. In particular, Fisher’s model assumes that each trait contributes independently to fitness. Here, we show that Haldane’s concerns may be incorporated into Fisher’s model solely by allowing the intensity of selection to vary between traits. We further show that this generalization may be achieved by introducing a single, intuitively defined quantity that describes the phenotype prior to adaptation. Comparing the process of adaptation under the original and generalized models, we show that the generalization may bias results toward either larger or smaller mutations. The applicability of Fisher’s model is then discussed

Platforms prepare manufacturing for rapid responses

Recent outbreaks have created an awareness of the complexity of manufacturing vaccines and therapeutics in time to address an emerging infectious disease threat. Emergent BioSolutions, as an HHS/ASPR/BARDA (Biodefense Advanced Research and Development Authority) Center for Innovation in Advanced Development and Manufacturing (CIADM), facilitates advanced development of chemical, biological, radiological, and nuclear (CBRN) medical countermeasures and ensures domestic manufacturing surge capacity to address the US government’s preparedness priorities and needs. Emergent has a broad range of vaccine manufacturing experience and has been evaluating and implementing processes for the rapid manufacture of vaccines and therapeutics to address these events. For products in pre-clinical development, the use of an expression system with an established manufacturing platform greatly reduces time to initiate manufacturing and increases the probability of success. In addition, platform processes allow for some in-process and release tests to be developed and ready for implementation. However, success is still not guaranteed as challenges with purity, potency, yield and stability may still be encountered. While some of these challenges can be overcome by approaches such as developing and validating platforms, additional challenges may still be present such as availability of testing and fill/finish facilities and preparation and agreement on necessary legal and regulatory documents. Timelines for manufacture are still several months at the minimum and may take significantly longer. Preparing platforms for the response to a potential infectious disease outbreak in advance is the best way to have effective vaccines and therapeutics ready to counter it

Definitive crystal structure of 1,1'-bis[1,2-dicarba-<i>clos</i>o-dodecaborane(11)]

In the title compound, C4H22B20, the two {1,2-closo-C2B10H11} cages are linked across a centre of inversion with a C—C distance of 1.5339 (11) Å. By careful analysis of the structure, it is established that the non-linking cage C atom is equally disordered over cage vertices 2 and 3

Crystal structure of 1,1'-bis[1,7-dicarba-<i>closo</i>-dodecaborane(11)]

In the title compound, C4H22B20, the two {1,7-closo-C2B10H11} cages are linked across a centre of inversion, with C—C = 1.5401 (16) Å. The position of the second non-linking cage C atom was established unambiguously by geometric and crystallographic methods and there is no evidence of C/B disorder

Exploring the Graduation Gap Between Oregon Virtual and Traditional High Schools

The purpose of this causal-comparative study was to compare graduation rates, defined as completing high school within five years, of students who learned online in Oregon virtual schools to students who attended traditional schools. The study utilized longitudinal data provided by the Oregon Department of Education connected to literature-supported graduation indicators to explore and compare graduation rates of traditional and virtual students. Analysis of data in the study was guided by three research questions: (1) when examining the ratio of the number of school days spent in a virtual school setting to the student graduation rates, does the increase of days in a virtual setting impact the likelihood of high school graduation, defined as completing 24 credits, (2) do predictive graduation indicators from the literature (i.e., attendance, behavior, demographics, performance, and mobility) explain the discrepancy, if any, in virtual and non-virtual Oregon five-year high school graduation rates, and (3) what combination of indicators is most useful for predicting a virtual student’s graduation outcome? The analysis used descriptive statistics and binary logistic regression to address the research questions. Key findings of the study included: attending a virtual school was not a good predictor of whether a student would graduate; behavior was not an effective indicator in virtual schools; it was easier to predict a graduate than a non-graduate; adding measures of mobility to previously studied indicators, attendance, behavior, and course performance, improved the ability to predict graduation outcomes for both traditional and virtual students; for virtual students, results of this study suggest that mobility may be a valuable substitute for behavior in a predictive model focused on students who attend school virtually

A Systematic Approach To Teaching Critical Thinking Skills To Electrical And Computer Engineering Undergraduates

Coursework that instills patterns of rigorous logical thought has long been a hallmark of the engineering curriculum.  However, today’s engineering students are expected to exhibit a wider range of thinking capabilities both to satisfy ABET requirements and to prepare the students to become successful practitioners.  This paper presents the initial results from a systematic effort to incorporate broader critical thinking instruction and assessment into electrical and computer engineering education as part of a university-wide quality enhancement program.  All incoming freshmen are given explicit and implicit instruction in critical thinking in ENGR 100: Introduction to Engineering and other engineering fundamentals courses, using the Paul-Elder framework of critical thinking to define and operationalize critical thinking.  This critical thinking foundation is reinforced later in the disciplinary courses so that students integrate critical thinking with the basic principles and practices of engineering.  In the Electrical and Computer Engineering (ECE) program, at the sophomore level, students use critical thinking skills which were developed during their engineering fundamentals courses, to analyze requirements and constraints which would apply in real-world design projects.  At the junior level, similar use of critical thinking is applied in an introductory computing methods course; and at the senior level, critical thinking skills are again strengthened and assessed in the capstone design course and in the professional issues and current topics seminar.  The latter course emphasizes understanding of professional ethics and current topics in electrical and computer engineering.  Initial data from this pilot implementation indicates statistically significant improvement in critical thinking skills in ECE students who have progressed through this sequence, and as a side benefit, it appears that writing skills also improve

Monitoring Seasonal Snow Density from Satellite Based Passive Microwave Remote Sensing and Automatic Weather Stations

Seasonal snow plays an important role in Earth’s systems and for hydrological applications one of the most important properties is the quantity of liquid water stored in the snowpack, referred to as snow water equivalent (SWE). SWE is related to the depth and density of a snowpack, so accurate estimates of both those properties are necessary to estimate SWE. However, the current understanding of snow density is limited to sparsely distributed in situ samples, which is especially limiting in an environment with restricted access like the Canadian tundra. Models can be used to estimate snow density in lieu of in situ sampling and there are a variety of such models available. However, it was determined that none of the available snow density models were entirely suitable for an environment like the Canadian tundra, each for their own reasons. A new remote sensing algorithm was proposed to estimate snow density from satellite based passive microwave observations and operational automatic weather station (AWS) networks. In this research, an experiment was designed to evaluate the potential for the remote sensing algorithm to monitor snow density in the Canadian Tundra. AWS data were used parametrize a two-layer snowpack model (representing a depth hoar layer underlying a wind slab) and 3D gradient descent machine learning was used to isolate the volume scattering contributions of each layer density independently. New components were added to the machine learning cost function to incorporate prior knowledge and constrain the model’s behaviour. The model was trained at the AWS site in Eureka, Nunavut and was then applied to AWS sites distributed across the Canadian tundra. Model performance was quite consistent at high arctic sites but began to degrade across the subarctic with increased distance from the training site, suggesting the need for more robust model training and forcing in the future. Estimation skill consistently improved over the course of algorithm runs and snow density estimates were often close to the ±10% uncertainty range of the in situ samples by the end of the season – showing good promise for estimating snow density at peak SWE accumulation, which could be useful for applications where total water storage in the snowpack is of concern

Bioresorbable Film for the Prevention of Adhesion to the Anterior Spine After Anterolateral Discectomy

Background context The development of scar tissue and adhesions postoperatively is a natural consequence of healing but can be associated with medical complications and render reoperation difficult. Many biocompatible products have been evaluated as barriers or deterrents to adhesions. Purpose To evaluate the efficacy of a bioresorbable polylactide film as a barrier to adhesion formation after anterolateral discectomy. Study design Experimental study. Methods Seven, skeletally mature female sheep underwent a retroperitoneal approach to the anterolateral lumbar spine. A discectomy was performed at two levels with an intervening unoperated disc site. One site was treated with a polylactide film barrier (Hydrosorb Shield; MacroPore Biosurgery, San Diego, CA) affixed with tacks manufactured from the same material. The second site was left untreated. Treatment and control sites were randomly assigned. Postmortem analysis included scar tenacity scoring on five spines and histological evaluation on two spines. Results The application of the Hydrosorb film barrier allowed a definite dissection plane during scar tenacity scoring and there was a significant difference in the development of adhesions to the disc between the control and treated sites. Histological evaluation revealed evidence of barrier formation to scar tissue and no significant adverse inflammatory reactions. Conclusions Hydrosorb Shield appears to be an effective postoperative barrier to scar tissue adhesion after anterolateral discectomy. The use of polylactide tacks was beneficial to affix the barrier film in place. Safety issues associated with delayed healing or adverse response to the film or tacks were not observed. Hydrosorb film may be useful as an antiadhesion barrier facilitating dissection during surgical revision in anterior approaches to the spine. Further studies are indicated to evaluate the performance of the bioresorbable material as an antiadhesion barrier in techniques of spinal fusion and disc replacement