Elastic cavitation, tube hollowing, and differential growth in plants and biological tissues

Elastic cavitation is a well-known physical process by which elastic materials under stress can open cavities. Usually, cavitation is induced by applied loads on the elastic body. However, growing materials may generate stresses in the absence of applied loads and could induce cavity opening. Here, we demonstrate the possibility of spontaneous growth-induced cavitation in elastic materials and consider the implications of this phenomenon to biological tissues and in particular to the problem of schizogenous aerenchyma formation

Interpersonal prosodic correlation in frontotemporal dementia.

Communication accommodation describes how individuals adjust their communicative style to that of their conversational partner. We predicted that interpersonal prosodic correlation related to pitch and timing would be decreased in behavioral variant frontotemporal dementia (bvFTD). We predicted that the interpersonal correlation in a timing measure and a pitch measure would be increased in right temporal FTD (rtFTD) due to sparing of the neural substrate for speech timing and pitch modulation but loss of social semantics. We found no significant effects in bvFTD, but conversations including rtFTD demonstrated higher interpersonal correlations in speech rate than healthy controls

Using Theory to Develop Healthy Choices in Motion, a Comprehensive, Experiential Physical Activity Curriculum.

Background: Research has shown that engaging in regular physical activity supports physiologic, metabolic, and immunologic processes, as well as quality of life. However, few youth in the United States meet the U.S. Department of Health and Human Services recommendation of 60 min of moderate-to-vigorous physical activity every day. School-based programs can be an effective avenue for engaging youth in physical activity, particularly when the design of the health education is based on theory, research, and practice. The purpose of this study was to design, implement, and evaluate a theory-driven physical activity curriculum for the Shaping Healthy Choices Program (SHCP) using a systematic approach. Methods: The experiential, inquiry-based physical activity curriculum, Healthy Choices in Motion (HCIM), was developed with an optional technology enhancement using Backward Design. A questionnaire to assess the curriculum's effect on physical activity knowledge was developed and assessed for content validity, internal consistency (α = 0.84), and test-retest reliability (r = 0.73). The curriculum was piloted in two phases among upper elementary-aged youth: to ensure the learning goals were met (Pilot I) and to determine the curriculum's impact on physical activity knowledge, behavior, and self-efficacy (Pilot II). Pilot II was implemented among eight 4th and 5th-grade classrooms participating in the UC CalFresh Nutrition Education Program: (1) Comparison (no intervention) (n = 25); (2) SHCP only (n = 22); (3) SHCP + HCIM (n = 42); (4) SHCP + HCIM with technology enhancement (n = 47). Analyses included unadjusted ANOVA and Bonferroni for multiple comparisons and paired t-test (p < 0.05). Results: Through the use of a methodical design approach, a comprehensive physical activity curriculum, called HCIM, was developed. Youth participating in HCIM improved physical activity knowledge compared to youth receiving no intervention (+2.8 points, p = 0.009) and youth only in the SHCP (+3.0 points, p = 0.007). Youth participating in HCIM with technology enhancement demonstrated improvements compared to youth only in the SHCP (+2.3 points, p = 0.05). Conclusion: Improvements in physical activity knowledge in youth participating in HCIM may contribute to improvements in physical activity and should be further explored in conjunction with behavioral measurements

A Droplet within the Spherical Model

Various substances in the liquid state tend to form droplets. In this paper the shape of such droplets is investigated within the spherical model of a lattice gas. We show that in this case the droplet boundary is always diffusive, as opposed to sharp, and find the corresponding density profiles (droplet shapes). Translation-invariant versions of the spherical model do not fix the spatial location of the droplet, hence lead to mixed phases. To obtain pure macroscopic states (which describe localized droplets) we use generalized quasi-averaging. Conventional quasi-averaging deforms droplets and, hence, can not be used for this purpose. On the contrary, application of the generalized method of quasi-averages yields droplet shapes which do not depend on the magnitude of the applied external field.Comment: 22 pages, 2 figure

Methsnotrophic Biodegradation of Trichloroethylene in a Hollow Fiber Membrane Bioreactor

Biodegradation of Trichloroethlyene (TCE) in a Hollow Fiber Membrane Bioreactor Was Investigated using a Mutant of the Methanotrophic Bacteria, Methylosinus Trichosporium 0B3b. Contaminated Water Flowed through the Lumen (I.e., Fiber Interior), and the Bacteria Circulated through the Shell Side of the Membrane Module and an External Growth Reactor. in Mass Transfer Studies with a Radial Cross-Flow Membrane Module, 78.3-99.9% of the TCE Was Removed from the Lumen at Hydraulic Residence Times of 3-15 Min in the Lumen and the Shell. in Biodegradation Experiments, 80-95% of the TCE Was Removed from the Lumen at Hydraulic Residence Times of 5-9 Min in the Lumen. the TCE Transferred to the Shell Was Rapidly Biodegraded, with Rate Constants Ranging from 0.16 to 0.9 L (Mg of TSS)-1 Day-1. Radiochemical Data Showed that over 75% of the Transferred TCE Was Biodegraded in the Shell, with the Byproducts Being Approximately Equally Divided between Carbon Dioxide and Nonvolatiles. This Study Shows that a Hollow Fiber Membrane Bioreactor System Coupled with the Mutant Strain PP358 of M. Trichosporium 0B3b is a Very Promising Technology for Chlorinated Solvent Biodegradation. © 1995, American Chemical Society. All Rights Reserved

Collaborative multidisciplinary learning : quantity surveying students’ perspectives

The construction industry is highly fragmented and is known for its adversarial culture, culminating in poor quality projects not completed on time or within budget. The aim of this study is thus to guide the design of QS programme curricula in order to help students develop the requisite knowledge and skills to work more collaboratively in their multi-disciplinary future workplaces. A qualitative approach was considered appropriate as the authors were concerned with gathering an initial understanding of what students think of multi-disciplinary learning. The data collection method used was a questionnaire which was developed by the Behaviours4Collaboration (B4C) team. Knowledge gaps were still found across all the key areas where a future QS practitioner needs to be collaborative (either as a project contributor or as a project leader) despite the need for change instigated by the multi-disciplinary (BIM) education revolution. The study concludes that universities will need to be selective in teaching, and innovative in reorienting, QS education so that a collaborative BIM education can be effected in stages, increasing in complexity as the students’ technical knowledge grows. This will help students to build the competencies needed to make them future leaders. It will also support programme currency and delivery

Scale-free Networks from Optimal Design

A large number of complex networks, both natural and artificial, share the presence of highly heterogeneous, scale-free degree distributions. A few mechanisms for the emergence of such patterns have been suggested, optimization not being one of them. In this letter we present the first evidence for the emergence of scaling (and smallworldness) in software architecture graphs from a well-defined local optimization process. Although the rules that define the strategies involved in software engineering should lead to a tree-like structure, the final net is scale-free, perhaps reflecting the presence of conflicting constraints unavoidable in a multidimensional optimization process. The consequences for other complex networks are outlined.Comment: 6 pages, 2 figures. Submitted to Europhysics Letters. Additional material is available at http://complex.upc.es/~sergi/software.ht

Linearly Parameterized Bandits

We consider bandit problems involving a large (possibly infinite) collection of arms, in which the expected reward of each arm is a linear function of an $r$-dimensional random vector $\mathbf{Z} \in \mathbb{R}^r$, where $r \geq 2$. The objective is to minimize the cumulative regret and Bayes risk. When the set of arms corresponds to the unit sphere, we prove that the regret and Bayes risk is of order $\Theta(r \sqrt{T})$, by establishing a lower bound for an arbitrary policy, and showing that a matching upper bound is obtained through a policy that alternates between exploration and exploitation phases. The phase-based policy is also shown to be effective if the set of arms satisfies a strong convexity condition. For the case of a general set of arms, we describe a near-optimal policy whose regret and Bayes risk admit upper bounds of the form $O(r \sqrt{T} \log^{3/2} T)$.Comment: 40 pages; updated results and reference

How do cities approach policy innovation and policy learning? A study of 30 policies in Northern Europe and North America

This paper reports on a study of current practice in policy transfer, and ways in which its effectiveness can be increased. A literature review identifies important factors in examining the transfer of policies. Results of interviews in eleven cities in Northern Europe and North America investigate these factors further. The principal motivations for policy transfer were strategic need and curiosity. Local officials and politicians dominated the process of initiating policy transfer, and local officials were also the leading players in transferring experience. A range of information sources are used in the search process but human interaction was the most important source of learning for two main reasons. First, there is too much information available through the Internet and the search techniques are not seen to be wholly effective in identifying the necessary information. Secondly, the information available on websites, portals and even good practice guides is not seen to be of mixed quality with risks of focussing only on successful implementation and therefore subject to some bias. Officials therefore rely on their trusted networks of peers for lessons as here they can access the ‘real implementation’ story and the unwritten lessons. Organisations which have a culture that is supportive of learning from elsewhere had strong and broad networks of external contacts and resourced their development whilst others are more insular or inward looking and reluctant to invest in policy lessons from elsewhere. Solutions to the problems identified in the evidence base are proposed