Structural-demographic analysis of the Qing Dynasty (1644-1912) collapse in China.

This paper analyzes the collapse of the Qing dynasty (1644-1912) through the lens of the Structural Demographic Theory (SDT), a general framework for understanding the drivers of socio-political instability in state-level societies. Although a number of competing ideas for the collapse have been proposed, none provide a comprehensive explanation that incorporates the interaction of all the multiple drivers involved. We argue that the four-fold population explosion peaking in the 19th century, the growing competition for a stagnant number of elite positions, and increasing state fiscal stress combined to produce an increasingly disgruntled populace and elite, leading to significant internal rebellions. We find that while neither the ecological disasters nor the foreign incursions during the 19th century were sufficient on their own to bring down the Qing, when coupled with the rising internal socio-political stresses, they produced a rapid succession of triggering events that culminated in the Qing collapse.

"Big Ideas" of Introductory Chemistry and Biology Courses and the Connections between Them.

Introductory courses are often designed to cover a range of topics with the intent to offer students exposure to the given discipline as preparation to further their study in the same or related disciplines. Unfortunately, students in these courses are often presented with an overwhelming amount of information that may not support their formation of a usable coherent network of knowledge. In this study we conducted a mixed-method sequential exploratory study with students co-enrolled in General Chemistry II and Introductory Biology I to better understand what students perceived to be the "take-home" messages of these courses (i.e., core ideas) and the connections between these courses. We found that students identified a range of ideas from both courses; further analysis of students' explanations and reasoning revealed that, when students talked about their chemistry ideas, they were more likely to talk about them as having predictive and explanatory power in comparison with reasons provided for their biology big ideas. Furthermore, students identified a number of overlapping ideas between their chemistry and biology courses, such as interactions, reactions, and structures, which have the potential to be used as a starting place to support students building a more coherent network of knowledge.

Connecting Structure-Property and Structure-Function Relationships across the Disciplines of Chemistry and Biology: Exploring Student Perceptions.

While many university students take science courses in multiple disciplines, little is known about how they perceive common concepts from different disciplinary perspectives. Structure-property and structure-function relationships have long been considered important explanatory concepts in the disciplines of chemistry and biology, respectively. Fourteen university students concurrently enrolled in introductory chemistry and biology courses were interviewed to explore their perceptions regarding 1) the meaning of structure, properties, and function; 2) the presentation of these concepts in their courses; and 3) how these concepts might be related. Findings suggest that the concepts of structure and properties were interpreted similarly between chemistry and biology, but students more closely associated the discussion of structure-property relationships with their chemistry courses and structure-function with biology. Despite receiving little in the way of instructional support, nine students proposed a coherent conceptual relationship, indicating that structure determines properties, which determine function. Furthermore, students described ways in which they connected and benefited from their understanding. Though many students are prepared to make these connections, we would encourage instructors to engage in cross-disciplinary conversations to understand the shared goals and disciplinary distinctions regarding these important concepts in an effort to better support students unable to construct these connections for themselves.

Preoperative dobutamine stress echocardiography in patients undergoing orthotopic liver transplantation.

BACKGROUND: Coronary artery disease (CAD) is associated with increased mortality in patients who undergo orthotopic liver transplantation (OLT). Chronic vasodilatory state and poor exercise tolerance in patients with end-stage liver disease make dobutamine stress echocardiography (DSE) preferred for preoperative evaluation of CAD prior to OLT. We studied the incidence of positive DSE results and the association between DSE results and perioperative and longer-term events. HYPOTHESIS: DSE results pre-OLT will predict short and long term outcomes. METHODS: We studied 460 patients who underwent DSE within 1 year prior to OLT between 2004 and 2011. Primary events included death and MI at 30 days post-OLT. We also recorded longer-term deaths. RESULTS: Four patients (0.9%) had an ischemic response to DSE, 360 (78%) were normal, and 96 (21%) were nondiagnostic. Fourteen patients (3%) had a primary event at 30 days following OLT (13 deaths and 1 NSTEMI), and there were 108 (24%) deaths at 4.6±2 years of follow-up. No patient with ischemia on DSE had a 30-day event. The accuracy, sensitivity, specificity, and positive and negative predictive values of DSE that was not normal (ie, ischemic or nondiagnostic response) to predict 30-day post-OLT events were 76%, 14%, 78%, 2%, and 97%, respectively. On Cox survival analysis, only baseline left ventricular ejection fraction (HR: 0.90, 95% CI: 0.85-0.96, P < 0.001) was associated with longer-term deaths. CONCLUSIONS: Patients undergoing pre-OLT DSE have very low incidence of an ischemic response on DSE, and it has no association with 30-day events.

Energy Connections and Misconnections across Chemistry and Biology.

Despite the number of university students who take courses in multiple science disciplines, little is known about how they connect concepts between disciplines. Energy is a concept that underlies all scientific phenomena and, as such, provides an appropriate context in which to investigate student connections and misconnections across disciplines. In this study, university students concurrently enrolled in introductory chemistry and biology were interviewed to explore their perceptions of the integration of energy both within and across the disciplines, and how they attempted to accommodate and reconcile different disciplinary approaches to energy, to inform future, interdisciplinary course reform. Findings suggest that, while students believed energy to be important to the scientific world and to the disciplines of biology and chemistry, the extent to which it was seen as central to success in their courses varied. Differences were also apparent in students' descriptions of the molecular-level mechanisms by which energy transfer occurs. These findings reveal a disconnect between how energy is understood and used in introductory science course work and uncovers opportunities to make stronger connections across the disciplines. We recommend that instructors engage in interdisciplinary conversations and consider the perspectives and goals of other disciplines when teaching introductory science courses.