Design and performance of an automatic regenerating adsorption aerosol dryer for continuous operation at monitoring sites

Sizes of aerosol particles depend on the relative humidity of their carrier gas. Most monitoring networks require therefore that the aerosol is dried to a relative humidity below 50% r.H. to ensure comparability of measurements at different sites. Commercially available aerosol dryers are often not suitable for this purpose at remote monitoring sites. Adsorption dryers need to be regenerated frequently and maintenance-free single column Nafion dryers are not designed for high aerosol flow rates. We therefore developed an automatic regenerating adsorption aerosol dryer with a design flow rate of 1 m3/h. Particle transmission efficiency of this dryer has been determined during a 3 week experiment. The lower 50% cut-off was found to be smaller than 3 nm at the design flow rate of the instrument. Measured transmission efficiencies are in good agreement with theoretical calculations. One dryer has been successfully deployed in the Amazon river basin. We present data from this monitoring site for the first 6 months of measurements (February 2008–August 2008). Apart from one unscheduled service, this dryer did not require any maintenance during this time period. The average relative humidity of the dried aerosol was 27.1+/−7.5% r.H. compared to an average ambient relative humidity of nearly 80% and temperatures around 30°C. This initial deployment demonstrated that these dryers are well suitable for continuous operation at remote monitoring sites under adverse ambient conditions

Validation of automated scoring for learning progression-aligned Next Generation Science Standards performance assessments

IntroductionThe Framework for K-12 Science Education promotes supporting the development of knowledge application skills along previously validated learning progressions (LPs). Effective assessment of knowledge application requires LP-aligned constructed-response (CR) assessments. But these assessments are time-consuming and expensive to score and provide feedback for. As part of artificial intelligence, machine learning (ML) presents an invaluable tool for conducting validation studies and providing immediate feedback. To fully evaluate the validity of machine-based scores, it is important to investigate human-machine score consistency beyond observed scores. Importantly, no formal studies have explored the nature of disagreements between human and machine-assigned scores as related to LP levels.MethodsWe used quantitative and qualitative approaches to investigate the nature of disagreements among human and scores generated by two approaches to machine learning using a previously validated assessment instrument aligned to LP for scientific argumentation.ResultsWe applied quantitative approaches, including agreement measures, confirmatory factor analysis, and generalizability studies, to identify items that represent threats to validity for different machine scoring approaches. This analysis allowed us to determine specific elements of argumentation practice at each level of the LP that are associated with a higher percentage of misscores by each of the scoring approaches. We further used qualitative analysis of the items identified by quantitative methods to examine the consistency between the misscores, the scoring rubrics, and student responses. We found that rubrics that require interpretation by human coders and items which target more sophisticated argumentation practice present the greatest threats to the validity of machine scores.DiscussionWe use this information to construct a fine-grained validity argument for machine scores, which is an important piece because it provides insights for improving the design of LP-aligned assessments and artificial intelligence-enabled scoring of those assessments

Th1/M1 Conversion to Th2/M2 Responses in Models of Inflammation Lacking Cell Death Stimulates Maturation of Monocyte Precursors to Fibroblasts

We have demonstrated that cardiac fibrosis arises from the differentiation of monocyte-derived fibroblasts. We present here evidence that this process requires sequential Th1 and Th2 induction promoting analogous M1 (classically activated) and M2 (alternatively activated) macrophage polarity. Our models are: (1) mice subjected to daily repetitive ischemia and reperfusion (I/R) without infarction and (2) the in vitro transmigration of human mononuclear leukocytes through human cardiac microvascular endothelium. In the mouse heart, leukocytes entered after I/R in response to monocyte chemoattractant protein-1 (MCP-1), which is the major cytokine induced by this protocol. Monocytes within the heart then differentiated into fibroblasts making collagen while bearing the markers of M2 macrophages. T cells were seen in these hearts as well as in the human heart with cardiomyopathy. In the in vitro model, transmigration of the leukocytes was likewise induced by MCP-1 and some monocytes matured into fibroblasts bearing M2 markers. In this model, the MCP-1 stimulus induced a transient Th1 and M1 response that developed into a predominantly Th2 and M2 response. An increase in the Th2 product IL-13 was present in both the human and the mouse models, consistent with its known role in fibrosis. In these simplified models, in which there is no cell death to stimulate an anti-inflammatory response, there is nonetheless a resolution of inflammation enabling a profibrotic environment. This induces the maturation of monocyte precursors into fibroblasts

Mixed Student Ideas about Mechanisms of Human Weight Loss

Recent calls for college biology education reform have identified “pathways and transformations of matter and energy” as a big idea in biology crucial for students to learn. Previous work has been conducted on how college students think about such matter-transforming processes; however, little research has investigated how students connect these ideas. Here, we probe student thinking about matter transformations in the familiar context of human weight loss. Our analysis of 1192 student constructed responses revealed three scientific (which we label “Normative”) and five less scientific (which we label “Developing”) ideas that students use to explain weight loss. Additionally, students combine these ideas in their responses, with an average number of 2.19 ± 1.07 ideas per response, and 74.4% of responses containing two or more ideas. These results highlight the extent to which students hold multiple (both correct and incorrect) ideas about complex biological processes. We described student responses as conforming to either Scientific, Mixed, or Developing descriptive models, which had an average of 1.9 ± 0.6, 3.1 ± 0.9, and 1.7 ± 0.8 ideas per response, respectively. Such heterogeneous student thinking is characteristic of difficulties in both conceptual change and early expertise development and will require careful instructional intervention for lasting learning gains

Introductory biology undergraduate students\u27 mixed ideas about genetic information flow

The core concept of genetic information flow was identified in recent calls to improve undergraduate biology education. Previous work shows that students have difficulty differentiating between the three processes of the Central Dogma (CD; replication, transcription, and translation). We built upon this work by developing and applying an analytic coding rubric to 1050 student written responses to a three‐question item about the CD. Each response was previously coded only for correctness using a holistic rubric. Our rubric captures subtleties of student conceptual understanding of each process that previous work has not yet captured at a large scale. Regardless of holistic correctness scores, student responses included five or six distinct ideas. By analyzing common co‐occurring rubric categories in student responses, we found a common pair representing two normative ideas about the molecules produced by each CD process. By applying analytic coding to student responses preinstruction and postinstruction, we found student thinking about the processes involved was most prone to change. The combined strengths of analytic and holistic rubrics allow us to reveal mixed ideas about the CD processes and provide a detailed picture of which conceptual ideas students draw upon when explaining each CD process

SR proteins and galectins: what's in a name?

Although members of the serine (S)- and arginine (R)-rich splicing factor family (SR proteins) were initially purified on the basis of their splicing activity in the nucleus, there is recent documentation that they exhibit carbohydrate-binding activity at the cell surface. In contrast, galectins were isolated on the basis of their saccharide-binding activity and cell surface localization. Surprisingly, however, two members (galectin-1 and galectin-3) can be found in association with nuclear ribonucleoprotein complexes including the spliceosome and, using a cell-free assay, have been shown to be required splicing factors. Thus, despite the difference in terms of their original points of interest, it now appears that members of the two protein families share four key properties: (a) nuclear and cytoplasmic distribution; (b) pre-mRNA splicing activity; (c) carbohydrate-binding activity; and (d) cell surface localization in specific cells. These findings provoke stimulating questions regarding the relationship between splicing factors in the nucleus and carbohydrate-binding proteins at the cell surface

Deconstruction of Holistic Rubrics into Analytic Rubrics for Large-Scale Assessments of Students’ Reasoning of Complex Science Concepts

Constructed responses can be used to assess the complexity of student thinking and can be evaluated using rubrics. The two most typical rubric types used are holistic and analytic. Holistic rubrics may be difficult to use with expert-level reasoning that has additive or overlapping language. In an attempt to unpack complexity in holistic rubrics at a large scale, we have developed a systematic approach called deconstruction. We define deconstruction as the process of converting a holistic rubric into defining individual conceptual components that can be used for analytic rubric development and application. These individual components can then be recombined into the holistic score which keeps true to the holistic rubric purpose, while maximizing the benefits and minimizing the shortcomings of each rubric type. This paper outlines the deconstruction process and presents a case study that shows defined concept definitions for a hierarchical holistic rubric developed for an undergraduate physiology-content reasoning context. These methods can be used as one way for assessment developers to unpack complex student reasoning, which may ultimately improve reliability and validation of assessments that are targeted at uncovering large-scale complex scientific reasoning. Accessed 398 times on https://pareonline.net from September 05, 2019 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right

Tissue Microenvironments Define and Get Reinforced by Macrophage Phenotypes in Homeostasis or during Inflammation, Repair and Fibrosis

Current macrophage phenotype classifications are based on distinct in vitro culture conditions that do not adequately mirror complex tissue environments. In vivo monocyte progenitors populate all tissues for immune surveillance which supports the maintenance of homeostasis as well as regaining homeostasis after injury. Here we propose to classify macrophage phenotypes according to prototypical tissue environments, e.g. as they occur during homeostasis as well as during the different phases of (dermal) wound healing. In tissue necrosis and/or infection, damage- and/or pathogen-associated molecular patterns induce proinflammatory macrophages by Toll-like receptors or inflammasomes. Such classically activated macrophages contribute to further tissue inflammation and damage. Apoptotic cells and antiinflammatory cytokines dominate in postinflammatory tissues which induce macrophages to produce more antiinflammatory mediators. Similarly, tumor-associated macrophages also confer immunosuppression in tumor stroma. Insufficient parenchymal healing despite abundant growth factors pushes macrophages to gain a profibrotic phenotype and promote fibrocyte recruitment which both enforce tissue scarring. Ischemic scars are largely devoid of cytokines and growth factors so that fibrolytic macrophages that predominantly secrete proteases digest the excess extracellular matrix. Together, macrophages stabilize their surrounding tissue microenvironments by adapting different phenotypes as feed-forward mechanisms to maintain tissue homeostasis or regain it following injury. Furthermore, macrophage heterogeneity in healthy or injured tissues mirrors spatial and temporal differences in microenvironments during the various stages of tissue injury and repair. Copyright (C) 2012 S. Karger AG, Base