Looking for evidence of learning: Assessment and analysis methods for online discourse

Discussion is a required component of many Web-based classes, but do we really know its value or contribution to learning? Students may be graded for participation, and number and length of posts may be counted by those evaluating or researching online classes, but all too often the assessment and analysis methods that we use fail to provide us with data that indicate learning took place through participation in online discussion. This paper explores what can be learned by currently popular assessment practices and analytic methods, as well as the limitations of these methods when used to measure learning, using two samples of discussion threads from online classes.     

Functional and nutritional value of the Chilean seaweeds Codium fragile,Gracilaria chilensis and Macrocystis pyrifera

The nutritional composition of the edible seaweeds Codium fragile, Gracilaria chilensis and Macrocystis pyrifera was determined, including amino acid and fatty acid contents along with tocol and carotenoid contents. The results indicated that the three algae C. fragile, G. chilensis and M. pyrifera showed a high range of protein contents (13.7–10.8%), amino acid contents (1879.6–1417.7 mg/100 g dry algae) and a low content in lipids (0.7–15.0%). The most abundant fatty acids in C. fragile and G. chilensis were linolenic, oleic, and linoleic acid. δ‐Tocopherol and α‐tocopherol (677.8 and 453.5 µg/g lipid, respectively) were found in C. fragile, while in G. chilensis and M. pyrifera, γ‐tocotrienol and α‐tocopherol (263.5 and 1327.7 µg/g lipid, respectively) were found. In addition, in C. fragile and G. chilensis β‐carotene was the principal carotenoid found (197.9 and 113.7 µg/g dry algae, respectively) compared with M. pyrifera (17.4 µg/g dry algae). The composition of macronutrients (minerals, carbohydrate‐type dietetic fiber, proteins; low in lipids) and micronutrients (essential amino acids, PUFA of balanced n‐6/n‐3 proportion, β‐carotene and α‐tocopherol as source of vitamins A and E), corroborate the nutritional and biological potential of the studied algae, which constitute useful raw materials for the development of diets or ingredients for human and animal nutrition.     

Use of mild irradiation doses to control pathogenic bacteria on meat trimmings for production of patties aiming at provoking minimal changes in quality attributes

The objectives of the present work were to assess the use of moderate doses of gamma irradiation (2 to 5 kGy) and to reduce the risk of pathogen presence without altering the quality attributes of bovine trimmings and of patties made of irradiated trimmings. Microbiological indicators (coliforms, Pseudomonas spp and mesophilic aerobic counts), physicochemical indicators (pH, color and tiobarbituric acid) and sensory changes were evaluated during storage. 5 kGy irradiation doses slightly increased off flavors in patties. Two pathogenic markers (Listeria monocytogenes and Escherichia coli O157:H7) were inoculated at high or low loads to trimming samples which were subsequently irradiated and lethality curves were obtained. Provided that using irradiation doses ≤ 2.5 kGy are used, reductions of 2 log CFU/g of L. monocytogenes and 5 log CFU/g of E. coli O157:H7 are expected. It seems reasonable to suppose that irradiation can be successfully employed to improve the safety of frozen trimmings when initial pathogenic bacteria burdens are not extremely high.     

Social preferences and economic valuation for water quality and river restoration: the Segura River,Spain

The Water Framework Directive (WFD) aims at improving the ecological status of the water bodies in Europe. In this context, some rivers are currently being restored and, in accordance with this Directive, the restoration actions have to be evaluated from a socio‐economic approach. This work applies the Choice Modelling method to the WFD provisions for river restoration. This method proves to be useful for the economic valuation of the restoration measures, as well as a very important tool for people's public participation. In this sense, the water quality improvement has been defined as a priority action from a social point of view. Moreover, the method used has provided answers to both basic questions included in the WFD: the calculation of the economic value of the Segura River's ecological flow, the decrease of which would pose an environmental cost, and the estimation of the environmental income generated by this river.     

Extraction and microencapsulation of bioactive compounds from pomegranate (Punica granatum var. Wonderful) residues

Pomegranate peels and seeds are industrial residues considered interesting sources of punicalagin (PU) and punicic acid (PA), respectively. To optimise their extraction process and protect them against environmental factors, pomegranate residues were extracted with supercritical CO₂ (SC‐CO₂) using a Box–Behnken design and then optimal extracts encapsulated by spray‐drying applying a 2² central composite design. Peel extracts showed a PU content of 0.4–9.5% with optimal extraction conditions of 400 bar, 43 °C and 20% ethanol. On the other hand, SC‐CO₂ seed extracts showed a PA content of 65.1–78.4% with 450 bar, 48 °C and 10% ethanol as optimal extraction parameters. Otherwise, the encapsulation efficiency of SC‐CO₂ extracts was significantly affected by core/wall material ratio and its quadratic effect. This parameter ranged from 35.1% to 72.4% for peel extracts and from 68.2% to 92.7% for seed extracts. Results showed that the proposed technologies are a feasible approach to the integral utilisation of residues from the pomegranate industry.     

Pedagogical lurking: Student engagement in non-posting discussion behavior

This paper presents the results of a study of student non-posting participation behavior in two online classes. Most often active message is assessed and thus implicitly valued in online class discussion, but the act of writing messages is not the only factor that contributes to student learning. However, it is the most visible and easiest to measure. Students may engage in processes of reading and reflection on the discussion board, not leaving their mark; it is these acts that may be referred to as pedagogical lurking. In this study, students were asked to self-report their non-visible course activities, the reasons behind these activities and their perceived usefulness related to learning. Findings show that about half of the students felt that they learned through the online discussion experience, and that they believe both posting and reading messages contributed to their ability to learn. These students were likely to enter the discussion before posting to obtain a model for participation, and to return at a later time to check for replies and reflect. Students who participated solely to meet course requirements and who focused on posting messages more than reading messages had less positive impressions of the discussion activity’s impact on learning.     

Effects of Historical Reasoning Instruction and Writing Strategy Mastery in Culturally and Academically Diverse Middle School Classrooms.

Seventy 8th-grade students (including talented writers, those with average ability, and students in need of special education services) participated in an integrated social studies and language arts unit designed to promote historical understandings and argumentative writing skills. The historical reasoning instruction lasted 12 days, and the writing instruction lasted 10 days. Students applied historical inquiry strategies when reading documents related to westward expansion and learned to plan argumentative essays related to each historical event. Results indicate that in comparison to 62 students in a control group who did not receive either form of instruction, students who demonstrated mastery of the target strategies during instruction wrote historically more accurate and more persuasive essays regardless of their initial learning profile. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of uncontrolled factors in a validated liquid chromatography-tandem mass spectrometry method question its use as a reference method for marine toxins: major causes for concern

Chromatographic techniques coupled to mass spectrometry is the method of choice to replace the mouse bioassay (MBA) to detect marine toxins. This paper evaluates the influence of different parameters such as toxin solvents, mass spectrometric detection method, mobile-phase-solvent brands and equipment on okadaic acid (OA), dinophysistoxin-1 (DTX-1), and dinophysistoxin-2 (DTX-2) quantification. In addition, the study compares the results obtained when a toxin is quantified against its own calibration curve and with the calibration curve of the other analogues. The experiments were performed by liquid chromatography (LC) and ultraperformance liquid chromatography (UPLC) with tandem mass spectrometry detection (MS/MS). Three acetonitrile brands and two toxin solvents were employed, and three mass spectrometry detection methods were checked. One method that contains the transitions for azaspiracid-1 (AZA-1), azaspiracid-2 (AZA-2), azaspiracid-3(AZA-3), gimnodimine (GYM), 13-desmethyl spirolide C (SPX-1), pectenotoxin-2 (PTX-2), OA, DTX-1, DTX-2, yessotoxin (YTX), homoYTX, and 45-OH-YTX was compared in both instruments. This method operated in simultaneous positive and negative ionization mode. The other two mass methods operated only in negative ionization mode, one contains transitions to detect DTX-1, OA DTX-2, YTX, homoYTX, and 45-OH-YTX and the other only the transitions for the toxins under study OA, DTX-1, and DTX-2. With dependence on the equipment and mobile phase used, the amount of toxin quantified can be overestimated or underestimated, up to 44% for OA, 46% for DTX-1, and 48% for DTX-2. In addition, when a toxin was quantified using the calibration curve of the other analogues, the toxin amount obtained is different. The maximum variability was obtained when DTX-2 was quantified using either OA or a DTX-1 calibration curve. In this case, the overestimation was up to 88% using the OA calibration curve and up to 204% using the DTX-1 calibration curve. In summary, the correct quantification of DSP toxins by MS detection depends on multiple factors. Since these factors are not taken into account in a validated protocol, these results question the convenience of having MS/MS as a reference method for protecting consumers of marine toxins, moreover if toxicity of each group is considered independently and total toxicity is not summed anymore as it is in the MBA.     

Health status measurement in Toxic Oil Syndrome

Toxic Oil Syndrome (TOS) is a previously unreported condition which affected more than 20,000 people in Spain in 1981 and whose natural history is unknown. In 1993-94, a stratified random sample of 1400 survivors was drawn to measure their health status through clinical examination and their self-perception of well-being through the Nottingham Health Profile Questionnaire (NHPQ). Two-thirds of the sample population responded; indirect estimates suggest that selection bias was limited. Clear and intermediate signs of neuropathy were found in one-fifth and one-half of the patients, respectively. One-fourth and one-sixth showed some degree of scleroderma and contractures. All conditions were more frequent in women than in men and in age >50 than in younger ages. Although no concurrent control group was included in the study, prevalences of these conditions are well above expectations and are largely attributable to TOS. NHPQ scores increased with age in both sexes up to age 50, after which they reached a plateau (with values around 48 in men and 62 in women). Scores were associated to the occurrence of peripheral neurological changes, contractures, and scleroderma-like conditions. A multivariate analysis indicated age, sex, and severity of neurological conditions as major determinants of the NHPQ scores. This overall pattern of findings is peculiar to TOS and differs from the typical post-disaster nonspecific syndrome.