Program Comprehension: Identifying Learning Trajectories for Novice Programmers

This working group asserts that Program Comprehension (PC) plays a critical part in the writing process. For example, this abstract is written from a basic draft that we have edited and revised until it clearly presents our idea. Similarly, a program is written in an incremental manner, with each step being tested, debugged and extended until the program achieves its goal. Novice programmers should develop their program comprehen- sion as they learn to code, so that they are able to read and reason about code while they are writing it. To foster such competencies our group has identified two main goals: (1) to collect and define learning activities that explicitly cover key components of program comprehension and (2) to define possible learning trajectories that will guide teachers using those learning activities in their CS0/CS1 or K-12 courses. [...

Identifying and alleviating the durability challenges in membrane-electrode-assembly devices for high-rate CO electrolysis

CO electrolysis (COE) has emerged as an important alternative technology to couple with other sustainable techniques for transitioning towards a carbon-neutral future. A large challenge for the deployment of high-rate COE is the limited durability of membrane-electrode assembly (MEA) devices. Here, by using an operando wide-angle X-ray scattering technique and monitoring the change of electrolyte, we identified several degradation mechanisms of the MEA during high-rate COE. Cathodic gas-diffusion electrode (GDE) flooding and Ir contaminants (crossover from anode) are two main issues causing excessive hydrogen evolution, which can be partly alleviated by increasing the polytetrafluoroethylene content in GDEs and using an alkaline stable Ni-based anode. During long-term stability, the dynamic evolution of anolyte became the main issue: the pH would continuously drop due to cathodic acetate formation and anodic ethanol oxidation. By compensating for this issue, we maintained a Faradaic efficiency of C2+ products at more than 70% for 136 hours. [Figure not available: see fulltext.]</p

Early diagnosis of lymphedema using multiple frequency bioimpedance

Multiple frequency bioelectrical impedance analysis (MFBIA) has previously been shown to provide accurate relative measures of lymphedema in the upper limb of patients (1). This paper reports the results of a three year prospective study to evaluate the efficacy of MFBIA to predict the early onset of lymphedema in patients following treatment for breast cancer. Bioelectrical impedance measurements and circumferential measurements of each upper limb were recorded in healthy control subjects (n=60) to determine the normal range of the ratio (dominant/non-dominant) of extracellular and total limb volumes respectively. Patients undergoing surgery for the treatment of breast cancer were recruited as the study group; MFBIA and circumferential measurements were recorded pre-surgery, one month post-surgery and then at two month intervals for 24 months. One hundred and two patients were recruited into the study. Twenty patients developed lymphedema in the 24 months follow up period of this study. In each of these 20 cases MFBIA predicted the onset of the condition up to 10 months before the condition could be clinically diagnosed. Estimates of the sensitivity and specificity were both approximately 100%. At the time of detection by MFBIA, only one of the patients returned a positive test result from the total limb volumes determined from the circumferential measures. These results confirmed the suitability of the MFBIA technique as a reliable diagnostic procedure for the early detection of lymphedema

Activin A induces dendritic cell migration through the polarized release of CXC chemokine ligands 12 and 14

Activin A is a dimeric protein, member of the transforming growth factor (TGF)– family that plays a crucial role in wound repair and in fetal tolerance. Emerging evidence also proposes activin Aas a key mediator in inflammation. This study reports that activin A induces the directional migration of immature myeloid dendritic cells (iDCs) through the activation of ALK4 and ActRIIA receptor chains. Conversely, activin A was not active on plasmacytoid dendritic cells (DCs) or mature myeloid DCs. iDC migration to activin A was phosphatidylinositol 3-kinase –dependent, Bordetella pertussis toxin– and cycloheximide-sensitive, and was inhibited by M3, a viral-encoded chemokinebinding protein. In a real-time video microscopy-based migration assay, activin A induced polarization of iDCs, but not migration. These characteristics clearly differentiated the chemotactic activities of activin A from TGF- and classic chemokines. By the use of combined pharmacologic and low-density microarray analysis, it was possible to define that activin-A–induced migration depends on the selective and polarized release of 2 chemokines, namely CXC chemokine ligands 12 and 14. This study extends the proinflammatory role of activin A to DC recruitment and provides a cautionary message about the reliability of the in vitro chemotaxis assays in discriminating direct versus indirect chemotactic agonists

Activin A induces dendritic cell migration through the polarized release of CXC chemokine ligands 12 and 14

Activin A is a dimeric protein, member of the transforming growth factor (TGF)– family that plays a crucial role in wound repair and in fetal tolerance. Emerging evidence also proposes activin Aas a key mediator in inflammation. This study reports that activin A induces the directional migration of immature myeloid dendritic cells (iDCs) through the activation of ALK4 and ActRIIA receptor chains. Conversely, activin A was not active on plasmacytoid dendritic cells (DCs) or mature myeloid DCs. iDC migration to activin A was phosphatidylinositol 3-kinase –dependent, Bordetella pertussis toxin– and cycloheximide-sensitive, and was inhibited by M3, a viral-encoded chemokinebinding protein. In a real-time video microscopy-based migration assay, activin A induced polarization of iDCs, but not migration. These characteristics clearly differentiated the chemotactic activities of activin A from TGF- and classic chemokines. By the use of combined pharmacologic and low-density microarray analysis, it was possible to define that activin-A–induced migration depends on the selective and polarized release of 2 chemokines, namely CXC chemokine ligands 12 and 14. This study extends the proinflammatory role of activin A to DC recruitment and provides a cautionary message about the reliability of the in vitro chemotaxis assays in discriminating direct versus indirect chemotactic agonists

Activin A induces dendritic cell migration through the polarized release of CXC chemokine ligands 12 and 14

Activin A is a dimeric protein, member of the transforming growth factor (TGF)-β family that plays a crucial role in wound repair and in fetal tolerance. Emerging evidence also proposes activin A as a key mediator in inflammation. This study reports that activin A induces the directional migration of immature myeloid dendritic cells (iDCs) through the activation of ALK4 and ActRIIA receptor chains. Conversely, activin A was not active on plasmacytoid dendritic cells (DCs) or mature myeloid DCs. iDC migration to activin A was phosphatidylinositol 3-kinase γ-dependent, Bordetella pertussis toxin- and cycloheximide-sensitive, and was inhibited by M3, a viral-encoded chemokine-binding protein. In a real-time video microscopy-based migration assay, activin A induced polarization of iDCs, but not migration. These characteristics clearly differentiated the chemotactic activities of activin A from TGF-β and classic chemokines. By the use of combined pharmacologic and low-density microarray analysis, it was possible to define that activin-A-induced migration depends on the selective and polarized release of 2 chemokines, namely CXC chemokine ligands 12 and 14. This study extends the proinflammatory role of activin A to DC recruitment and provides a cautionary message about the reliability of the in vitro chemotaxis assays in discriminating direct versus indirect chemotactic agonists

Versatile high energy X-ray transparent electrolysis cell for operando measurements

Herein we present a design for a versatile electrochemical cell for High Energy X-ray operando studies of Membrane Electrode Assembly (MEA) based electrochemical systems. The cell flowplate materials can be interchanged according to the needs of experiments, allowing studies of different chemistries and reactions. The design also allows for coupling the X-ray elastic scattering techniques with computed tomography reconstruction, opening the possibility of 3D mapping of chemical and structural properties in operating devices. The cell has originally been designed and tested for CO2 electrolysis performance studies using Wide Angle X-ray Scattering (WAXS) technique