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If an organic chemistry student explains that she represents a mechanistic step because ''it's a productive part of the mechanism,'' what meaning could the professor teaching the class attribute to this statement, what is actually communicated, and what does it mean for the student? The professor might think that the explanation is based on knowledge of equilibria of alternative steps. The professor might also assume that the student implies information about how one of the alternatives influences the energetics of subsequent steps or how subsequent steps influence the equilibria of the alternatives. Meanwhile, the student might literally mean that the step is represented simply because it leads to the product. Reasoning about energetic influences has much greater explanatory power than teleological reasoning taking the consequence of mechanistic steps as the reason for their prediction. In both cases, however, the same backward-oriented reasoning is applied. Information about subsequent parts in the mechanism is used to make a decision about prior parts. To qualitatively compare the reasoning patterns and the causality employed by students and expected by their professor, we used a mechanistic approach from philosophy of science that mirrors the directionality of a mechanism and its components: activities, entities, and their properties. Our analysis led to the identification of different reasoning patterns involving backward-oriented reasoning. Participants' use of properties gave additional insight into the students' reasoning and their professor's expectations, which supports the necessity for clear expectations in mechanistic reasoning in organic chemistry classrooms. We present a framework that offers a lens to clarify these expectations and discuss implications of the framework for improving student mechanistic reasoning in organic chemistry.

Students often struggle with solving mechanism problems in organic chemistry courses. They frequently focus on surface features, have difficulty attributing meaning to symbols, and do not recognize tasks that are different from the exact tasks practiced. To be more successful, students need to be able to extract salient features, map similarities to problems seen previously, and extrapolate while solving problems. In short, students must be able to recognize and generate abstractions. To help students in learning to solve problems, we need a better understanding of the nature of students' capacity for abstraction. Building upon an exploratory study (Sevian H., Bernholt S., Szteinberg G. A., Auguste S. and Pérez L. C., (2015), "Use of representation mapping to capture abstraction in problem solving in different courses in chemistry," "Chem. Educ. Res. Pract.," 16(3), 429-446), we applied the representation mapping model of Hahn and Chater (1998a) to characterize the abstraction employed by students while solving mechanistic problems in organic chemistry, and to measure students' growth in abstraction capacity across a semester. This model operationalizes abstraction by considering (a) the ways in which students match existing knowledge to new instances (abstracting) and (b) the level of abstractness of students' representations. We describe characteristic indicators of abstracting and abstractness. Trends were observable in the abstraction present in the reasoning of successful and unsuccessful problem solvers. Students who proposed plausible solutions used both strict or partial matching, but students who proposed implausible solutions tended to use strict matching. Students who proposed plausible solutions utilized higher levels of abstractness. This indicates that flexibility in abstraction processes may be important to successfully solve problems. The findings have implications for developing instructors' assessment practices in ways that build students' abstraction capacity.

The central goal of this study was to analyze the complexity of students' explanations about how and why chemical reactions happen in terms of the types of causal connections students built between expressed concepts and ideas. We were particularly interested in characterizing differences in the types of reasoning applied by students with different levels of training in the chemistry, from college to graduate school. Using a qualitative research approach, we identified diverse modes of reasoning expressed by students when engaged in the analysis of different sets of chemical reactions selected to produce a targeted compound. Main findings indicate that dominant modes of reasoning varied with educational level and the nature of the task. Although participants applied diverse modes of reasoning, linear causal reasoning was prevalent across educational levels and types of tasks. Many students tended to generate explanations based on the identification of a single agent that caused a sequential chain of events. Advanced undergraduate students in our sample generated the most complex explanations. The results of our study have important implications for the development of causal mechanistic reasoning in chemistry.

The central goal of this qualitative research study was to uncover major implicit assumptions that students with different levels of training in the discipline apply when thinking and making decisions about chemical reactions used to make a desired product. In particular, we elicited different ways of conceptualizing why chemical reactions happen (chemical causality), how these processes occur (chemical mechanism), and how they can be controlled (chemical control). In each of these areas we characterized conceptual modes with different explanatory power and explored how they were applied by participants when facing different types of questions. Our findings suggest potential paths in the development of understanding about chemical reactions in the context of making specific substances. Our study also highlights the benefits of analyzing students' understanding not only by focusing on implicit cognitive elements, but by using disciplinary crosscutting concepts as lenses of analysis. This articles contains notes and references.

Examines whether demographic and life-history traits are correlated with genetic structure based on mitochondrial (mt) DNA lineages of humpback whales in the Gulf of Maine. Factors that can affect population structure; Importance of mtDNA in identifying population structure; Development of oligonucleotide primers in the study.

Head oscillations in response to whole body oscillation of Parkinsonian patients before and after administration of levodopa were compared with those of normal subjects. Parkinsonian patients developed large increases in the amplitude of their head movements while fixating a stationary target after administration of levodopa. This increase was proportional to disease severity and was maximal in stage IV patients with levodopa induced dyskinesias. These findings indicate a fundamental yet reversible change in the strategy of eye-head coordination in Parkinsonian patients after administration of levodopa which may be due to release of normally inhibited visuo-vestibular reflexes. [ABSTRACT FROM AUTHOR]

Many Asian subjects were seen in London in the early 1970s with megaloblastic anaemia; in a majority of cases, this was dietary in origin. Pernicious anaemia occurs in Asians, but the incidence is probably lower than in Caucasians. Megaloblastic anaemia is now less common in this group, but a population survey in Punjabi females in the late 1970's showed anaemia in 32%, and one or more features of iron deficiency in 76%. [ABSTRACT FROM PUBLISHER]

A population-based survey of female Punjabi Indians aged 11 and over now living in Southall, a district in west London, showed a steady and significant increase in blood pressure with increasing age. The crude population prevalence of hypertension, defined according to the criteria of the World Health Organisation, was 16%; for women over the age of 40 it was 62%. About two-thirds of those in the hypertensive range did not know of their high blood pressure. Among those who did know, up to 75% were receiving medical treatment for the condition. [ABSTRACT FROM PUBLISHER]

Abstract Background The objective of this study was to examine the extent of surgical procedures, pathological findings, complications and outcome of patients treated in the last 12 years for gallbladder cancer. Methods The impact of a standardized more aggressive approach compared with historical controls of our center with an individual approach was examined. Of 53 patients, 21 underwent resection for cure and 32 for palliation. Results Overall hospital mortality was 9% and procedure related mortality was 4%. The standardized approach in UICC stage IIa, IIb and III led to a significantly improved outcome compared to patients with an individual approach (Median survival: 14 vs. 7 months, mean+/-SEM: 26+/-7 vs. 17+/-5 months, p = 0.014). The main differences between the standardized and the individual approach were anatomical vs. atypical liver resection, performance of systematic lymph dissection of the hepaticoduodenal ligament and the resection of the common bile duct. Conclusion Anatomical liver resection, proof for bile duct infiltration and, in case of tumor invasion, radical resection and lymph dissection of the hepaticoduodenal ligament are essential to improve outcome of locally advanced gallbladder cancer.

This study investigated the effects of an adaptive physical activity (APA) program on mobility function and quality of life (QOL) in chronic stroke patients. Twenty subjects with chronic hemiparesis completed a 2-month, combined group, class-home exercise regimen that emphasized mobility training. APA improved Berg Balance Scale scores (35 +/- 2 vs 45 +/- 2, p = 0.001), 6-minute walk distances (114 +/- 15 vs 142 +/- 7 m, p < 0.001), and Short Physical Performance Battery scores (3.2 +/- 0.4 vs 5.2 +/- 0.6, p < 0.001). Barthel Index scores increased (75 +/- 4 vs 84 +/- 4, p < 0.001), but Lawton scores were unchanged. Geriatric Depression Scale (p < 0.01) and Stroke Impact Scale (SIS), Mobility, Participation, and Recovery improved with APA (p < 0.03). APA has the potential to improve gait, balance, and basic but not instrumental activities of daily living profiles in individuals with chronic stroke. Improved depression and SIS scores suggest APA improves stroke-specific outcomes related to QOL. [ABSTRACT FROM AUTHOR]

The rapid pace of recent advances in development and application of electrical stimulation of the nervous system and in neural regeneration has created opportunities to combine these two approaches to restoration of function. This manuscript relates the discussion on this topic from a workshop at the International Functional Electrical Stimulation Society. The goals of this workshop were to discuss the current state of interaction between the fields of neural regeneration and neural prostheses and to identify potential areas of future research that would have the greatest impact on achieving the common goal of restoring function after neurological damage. Identified areas include enhancement of axonal regeneration with applied electric fields, development of hybrid neural interfaces combining synthetic silicon and biologically derived elements, and investigation of the role of patterned neural activity in regulating various neuronal processes and neurorehabilitation. Increased communication and cooperation between the two communities, and recognition by each field that the other has something to contribute to their efforts are needed to take advantage of these opportunities. In addition, creative grants combining the two approaches and more flexible funding mechanisms to support the convergence of their perspectives are necessary to achieve common objectives. [ABSTRACT FROM AUTHOR]