3,097 research outputs found
The Cultural Legacy of Communism in Entrepreneurship: Entrepreneurial Perceptions and Activity in Central and Eastern Europe
Using data from the Global Entrepreneurship Monitor, this paper examines differences in entrepreneurial perceptions (fear of failure, opportunity perception, self-efficacy, public opinion) between CEE and non-CEE countries, before and after the 2008 recession, as well as the effects of these perceptions on entrepreneurial motivation and overall levels of activity. The results suggest that CEE countries have systematically more pessimistic outlooks in terms of fear of failure and opportunity perception, but no difference from non-CEE countries in self-efficacy and public opinion. Additionally, most of the difference in fear of failure and opportunity perception, along with an increase in necessity-motivated entrepreneurship, comes after the recession, suggesting less durability and resilience of optimistic entrepreneurial perceptions in CEE countries. Finally, there is evidence of a higher threshold for a perceived opportunity to become a business reality in these post-socialist CEE countries
Control Systems Approach to Balance Stabilization during Human Standing and Walking.
Humans rely on cooperation from multiple sensorimotor processes to navigate a complex world. Poor function of one or more components can lead to reduced mobility or increased risk of falls, particularly with age. At present, quantification and characterization of poor postural control typically focus on single sensors rather than the ensemble and lack methods to consider the overall function of sensors, body dynamics, and actuators. To address this gap, I propose a controls framework based on simple mechanistic models to characterize and understand normative postural behavior. The models employ a minimal set of components that typify human behavior and make quantitative predictions to be tested against human data.
This framework is applied to four topics relevant to daily living: sensory integration for standing balance, limb coordination for one-legged balance, momentum usage in sit-to-stand maneuvers, and the energetic trade-offs of foot-to-ground clearance while walking. First, I demonstrate that integration of information from multiple physiological sensors can be modeled by an optimal state estimator. I show how such a model can predict human responses to conflict between visual, vestibular, and other sensors and use visual perturbation experiments to test this model. Second, I demonstrate that feedback control can model multi-limb coordination strategies during one-legged balance. I empirically identify a control law from human subjects and investigate how reducing stance ankle function necessitates greater gains from other limbs. Third, I show the advantages of momentum usage in sit-to-stand maneuvers. Counter to many human movements, this strategy is not performed with energetic economy, requiring excess mechanical work. However, with optimization models, I demonstrate that momentum serves to balance effort between knee and hip. Fourth, I propose a cost model for preferred ground clearance during swing phase of walking. Walking with greater foot lift is costly, but inadvertent ground contact is also costly. Therefore the tradeoff between these costly measures, modulated by movement variability, can explain expected cost of ground clearance. These controls-based models demonstrate the mechanisms behind normative behavior and enables predictions under novel situations. Thus these models may serve as diagnostic tools to identify poor postural control or aid design of intervention procedures.PhDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116654/1/amyrwu_1.pd
‘May I speak Cantonese?’ – Co-constructing a scientific proof in an EFL junior secondary science classroom
In this paper, an excerpt of teacher–student interaction in an EFL junior secondary science classroom in Hong Kong is analysed using the conversation analytic method of sequential analysis. The fine-grained analysis reveals that in the teacher's effort to engage her students in the co-construction of a scientific proof, the students' familiar everyday discourses (e.g. students' examples and experiences as expressed in their familiar language) need to be allowed to play a significant role. It also shows how translanguaging can be well-coordinated with multimodal practices (using blackboard drawings, gestures) to facilitate students' meaning-making in the inquiry-based teacher–student dialogue.postprin
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Deterministic Separation of Cancer Cells from Blood at 10 mL/min
Circulating tumor cells (CTCs) and circulating clusters of cancer and stromal cells have been identified in the blood of patients with malignant cancer and can be used as a diagnostic for disease severity, assess the efficacy of different treatment strategies and possibly determine the eventual location of metastatic invasions for possible treatment. There is thus a critical need to isolate, propagate and characterize viable CTCs and clusters. Here, we present a microfluidic device for mL/min flow rate, continuous-flow capture of viable CTCs from blood using deterministic lateral displacement arrays. We show here that a deterministic bump array can be designed such that it will isolate with efficiency greater than 85% CTCs over a large range in sizes from millimeter volume clinical blood samples in minutes, with no effect on cell vitality so that further culturing and analysis of the cells can be carried out
The Biology of Climate Change: The effects of changing climate on migrating and over-wintering species at a high-elevation field station
Students engage with long-term environmental and phenology data sets (spanning over 40 years) collected at the Rocky Mountain Biological Laboratory, a high-elevation field station in Colorado, to explore the effects of climate change on the phenology of migrating and hibernating species. After becoming familiar with the geographic context, people involved with the data collection, and organisms studied through background readings and videos, students explore the raw data set in Excel or using an interactive data visualization tool. In small groups, students reproduce figures and regressions from Inouye et al. (2000) based on those data, then expand their analyses with data collected during the subsequent decade. By comparing analyses that encompass different time spans, students evaluate the original interpretations from Inouye et al. (2000), explain possible discrepancies, and generate predictions for future patterns. Finally, students build upon their initial analyses by developing and testing hypotheses about patterns found in other organisms in the data set, and combine these to discuss the ecological consequences of shifting plant and animal phenology in group presentations
Biclustering random matrix partitions with an application to classification of forensic body fluids
Classification of unlabeled data is usually achieved by supervised learning
from labeled samples. Although there exist many sophisticated supervised
machine learning methods that can predict the missing labels with a high level
of accuracy, they often lack the required transparency in situations where it
is important to provide interpretable results and meaningful measures of
confidence. Body fluid classification of forensic casework data is the case in
point. We develop a new Biclustering Dirichlet Process (BDP), with a
three-level hierarchy of clustering, and a model-based approach to
classification which adapts to block structure in the data matrix. As the class
labels of some observations are missing, the number of rows in the data matrix
for each class is unknown. The BDP handles this and extends existing
biclustering methods by simultaneously biclustering multiple matrices each
having a randomly variable number of rows. We demonstrate our method by
applying it to the motivating problem, which is the classification of body
fluids based on mRNA profiles taken from crime scenes. The analyses of
casework-like data show that our method is interpretable and produces
well-calibrated posterior probabilities. Our model can be more generally
applied to other types of data with a similar structure to the forensic data.Comment: 45 pages, 10 figure
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