Prevention of fatty liver in transition dairy cows by subcutaneous injections of glucagon

The main objective of this study was to test the extent to which injecting glucagon subcutaneously for 14 d beginning at d 2 postpartum would prevent fatty liver development in transition dairy cows. Twenty-four multiparous Holstein cows were fed 6 kg of cracked corn in addition to their standard diet during the last 30 d of a dry period to induce postpartum development of fatty liver. Glucagon at either 7.5 or 15 mg/d or saline (control) was injected subcutaneously 3 times daily for 14 d beginning at d 2 postpartum. Glucagon at 15 mg/d prevented liver triacylglycerol accumulation in postpartum dairy cows. Glucagon at 7.5 mg/d showed potential for fatty liver prevention. Glucagon increased concentration of plasma glucose and insulin and decreased plasma nonesterified fatty acid concentrations. No effects of glucagon were detected on plasma β-hydroxybutyrate concentrations. Glucagon affected neither feed intake nor milk production. Moreover, milk composition was not altered by glucagon. Milk urea N concentrations decreased, and plasma urea N concentrations tended to decrease during glucagon administration, indicating that glucagon may improve protein use. Liver glycogen concentrations were not affected by glucagon. No significant differences in body condition scores were detected among treatments throughout the study. These results indicate that subcutaneous glucagon injections can prevent fatty liver in transition dairy cows without causing major production and metabolite disturbances.     

Tracing the development of teacher knowledge in a design seminar: Integrating content,pedagogy and technology

Effective technology integration for teaching subject matter requires knowledge not just of content, technology and pedagogy, but also of their relationship to each other. Building on Schulman’s [Schulman, L. S. (1987). Knowledge and teaching: foundations for a new reform. Harvard Educational Review, 57(1), 1–22] concept of pedagogical content knowledge, we introduce a framework for conceptualizing Technological Pedagogical Content Knowledge—TPCK [Mishra, P., Koehler, M.J., (in press). Technological pedagogical content knowledge: A new framework for teacher knowledge. Teachers College Record]. We report the results of a semester-long investigation of the development of TPCK during a faculty development design seminar, whereby faculty members worked together with masters students to develop online courses. Quantitative discourse analysis of 15 weeks of field notes for two of the design teams show participants moved from considering technology, pedagogy and content as being independent constructs towards a richer conception that emphasized connections among the three knowledge bases. Our analyses suggests that developing TPCK is a multigenerational process, involving the development of deeper understandings of the complex web of relationships between content, pedagogy and technology and the contexts in which they function. Pedagogic, pragmatic, theoretical, and methodological contributions are discussed.     

Modeling of a new recuperative thermoelectric cycle for a tumble dryer

Convection tumble dryers, employed with compression heat pumps, raise questions about the environmental friendliness of refrigerants utilized in the process. An attractive alternative to substitute these conventional systems is thermoelectric heat pumps which operate reliably, silently, and without using a harmful refrigerant. A new cycle that combines thermoelectric heat pumping with a recuperating heat exchanger is introduced. To evaluate the performance of such a dryer, a comprehensive model was developed, taking into account temperature dependent materials properties, contact resistances as well as thermal and electrical resistances. The model was validated on experimental data of a prototype thermoelectric heat exchanger. Modeling results show that thermoelectric heat-pumping-based convection tumble dryers are a promising technology.     

Household air pollution and blood markers of inflammation: A cross-sectional analysis

Household air pollution (HAP) from biomass stoves is a leading risk factor for cardiopulmonary outcomes; however, its toxicity pathways and relationship with inflammation markers are poorly understood. Among 180 adult women in rural Peru, we examined the cross-sectional exposure-response relationship between biomass HAP and markers of inflammation in blood using baseline measurements from a randomized trial. We measured markers of inflammation (CRP, IL-6, IL-10, IL-1β, and TNF-α) with dried blood spots, 48-h kitchen area concentrations and personal exposures to fine particulate matter (PM_2.5), black carbon (BC), and carbon monoxide (CO), and 48-h kitchen concentrations of nitrogen dioxide (NO₂) in a subset of 97 participants. We conducted an exposure-response analysis between quintiles of HAP levels and markers of inflammation. Markers of inflammation were more strongly associated with kitchen area concentrations of BC than PM_2.5. As expected, kitchen area BC concentrations were positively associated with TNF-α (pro-inflammatory) concentrations and negatively associated with IL-10, an anti-inflammatory marker, controlling for confounders in single- and multi-pollutant models. However, contrary to expectations, kitchen area BC and NO₂ concentrations were negatively associated with IL-1β, a pro-inflammatory marker. No associations were identified for IL-6 or CRP, or for any marker in relation to personal exposures.     

Dynamic and Steady-State Methods for Evaluation of CO-Tolerant Electrocatalysts and Membrane-Electrode-Assemblies

The operation of PEMFC stacks with impure hydrogen generated from reforming processes based on hydrocarbon fuels is associated with problems due to poisoning of the Pt based anode catalyst by carbon monoxide (CO) [1-3]. In order to address these problems, advanced CO tolerant PtRu electro-catalysts and MEAs have been developed by OMG over the past years [4-7]. In the course of this work, specific testing and evaluation methods for these products were established and implemented. During operation of PEMFC systems in vehicles and busses, transient exposure of the anode catalyst with high levels of CO can occur. To simulate these conditions in a lab environment, dynamic testing procedures simulating transient CO poisoning conditions were developed. For stationary PEMFC systems running on CO containing natural gas (NG) reformate, besides the production costs, endurance, stability and lifetime of MEAs are of primary importance. For this application field, the “CO-gain” diagnostic method was developed. This in-situ method allows to generate data and information on anode catalyst performance while performing a continuous, non-interrupted lifetime testing of the MEA. This paper describes the dynamic and steady-state testing methods developed and employed at OMG to evaluate CO tolerant electrocatalysts and membrane-electrode-assemblies (MEAs). For illustration, typical performance data obtained with the new testing procedures and methods are presented.