Reducing facet nucleation during algorithmic self-assembly

Algorithmic self-assembly, a generalization of crystal growth, has been proposed as a mechanism for bottom-up fabrication of complex nanostructures and autonomous DNA computation. In principle, growth can be programmed by designing a set of molecular tiles with binding interactions that enforce assembly rules. In practice, however, errors during assembly cause undesired products, drastically reducing yields. Here we provide experimental evidence that assembly can be made more robust to errors by adding redundant tiles that "proofread" assembly. We construct DNA tile sets for two methods, uniform and snaked proofreading. While both tile sets are predicted to reduce errors during growth, the snaked proofreading tile set is also designed to reduce nucleation errors on crystal facets. Using atomic force microscopy to image growth of proofreading tiles on ribbon-like crystals presenting long facets, we show that under the physical conditions we studied the rate of facet nucleation is 4-fold smaller for snaked proofreading tile sets than for uniform proofreading tile sets

IFU observations of luminous type II AGN - I. Evidence for ubiquitous winds

We present observations of 17 luminous (log(L[O III]/L_Sun) > 8.7) local (z < 0.11) type II AGN. Our aim is to investigate the prevalence and nature of AGN driven outflows in these galaxies by combining kinematic and ionization diagnostic information. We use non-parametric methods (e.g. W80, the width containing 80% of the line flux) to assess the line widths in the central regions of our targets. The maximum values of W80 in each galaxy are in the range 400 - 1600 km/s, with a mean of 790 +- 90 km/s. Such high velocities are strongly suggestive that these AGN are driving ionized outflows. Multi-Gaussian fitting is used to decompose the velocity structure in our galaxies. 14/17 of our targets require 3 separate kinematic components in the ionized gas in their central regions. The broadest components of these fits have FWHM = 530 - 2520 km/s, with a mean value of 920 +- 50 km/s. By simultaneously fitting both the H{\beta}/[O III] and H{\alpha}/[N II] complexes we construct ionization diagnostic diagrams for each component. 13/17 of our galaxies show a significant (> 95 %) correlation between the [N II]/H{\alpha} ratio and the velocity dispersion of the gas. Such a correlation is the natural consequence of a contribution to the ionization from shock excitation and we argue that this demonstrates that the outflows from these AGN are directly impacting the surrounding ISM within the galaxies.Comment: 37 pages, 30 figures. Accepted for publication in MNRA

Optimal content delivery with network coding

We present a unified linear program formulation for optimal content delivery in content delivery networks (CDNs), taking into account various costs and constraints associated with content dissemination from the origin server to storage nodes, data storage, and the eventual fetching of content from storage nodes by end users. Our formulation can be used to achieve a variety of performance goals and system behavior, including the bounding of fetch delay, load balancing, and robustness against node and arc failures. Simulation results suggest that our formulation performs significantly better than the traditional minimum k-median formulation for the delivery of multiple content, even under modest circumstances (small network, few objects, low storage budget, low dissemination costs)

Collaborative participatory research as a learning process: the case of CIP and CARE in Peru

Participatory research (PR) has been analyzed and documented from different points of view, but particularly taking into consideration the benefits that this process generates for farmers. Studies of the benefits of PR for other actors such as field staff, researchers and organizations have been limited, with organizational learning receiving the least attention. This paper analyzes the interaction between the International Potato Center (CIP) and CARE in Peru and makes the case that PR can also contribute to creating a collaborative learning environment that generates important lessons for the individuals and organizations involved. The paper describes the evolution of the collaborative environment of these two institutions for more than a decade. Three interactive learning periods are presented, namely the “information transfer period” (1993 –1996) the “action-learning period” (1997-2002), and the “social learning period” (on-going). Several lessons from each period, as well as changes in institutional contexts and perceptions, are described. The CIP-CARE case shows that research and developmentoriented organizations can interact fruitfully using PR as a mechanism to promote learning, as well as flexibility in interaction and innovativeness, and that a process of osmosis of information occurs between groups that use PR in a specific case to other groups within the organizations, influencing behavior. However, the paper also indicates that institutional learning should be promoted more specifically in order to extract guidelines from the lessons, which can influence the way organizations plan and implement their projects in a constantly changing environment

A new selective fluorescent probe based on tamoxifen

© 2016 Elsevier Ltd. Developing targeted validation probes that can interrogate biology is of interest for both chemists and biologists. The synthesis of suitable compounds provides a means for avoiding the costly labeling of cells with specific antibodies and the bias associated with the interpretation of biological validation experiments. The chemotherapeutic agent, tamoxifen has been routinely used in the treatment of breast cancer for decades. Once metabolized, the active form of tamoxifen (4-hydroxytamoxifen) competes with the binding of estrogens to the estrogen receptors (ER). Its selectivity in ER modulation makes it an ideal candidate for the development of materials to be used as chemical probes. Here we report the synthesis of a fluorescent BODIPY®FL conjugate of tamoxifen linked through an ethylene glycol moiety, and present proof-of-principle results in ER positive and ER negative cell lines. Optical microscopy indicates that the fluorescent probe binds selectively to tamoxifen sensitive breast cancer cell lines. The compound showed no affinity for the tamoxifen resistant breast cancer lines. The specificity of the new compound make it a valuable addition to the chemical probe tool kit for estrogen receptors

Numerical simulation of shock/cavitation-structure interaction

Master'sMASTER OF ENGINEERIN

Neighborhood Safety and Attractiveness Influence Physical Activity among African American and Hispanic or Latina Women

Introduction: Although the benefits of adopting physical activity (PA) are well publicized, physical inactivity rates remain high, and African American and Hispanic or Latina women do less PA compared to white women. Many interventions have begun to focus on conveniently performed lifestyle PA, such as walking. The purpose of this study was to investigate the relationship between neighborhood safety and attractiveness and PA in a sample of African American (AA) and Hispanic or Latina (HL) women participating in Health Is Power (1R01CA109403). Method: Women (AA N=202 and HL N=107) who enrolled in the study were middle-aged (M=45.8 years), overweight (M BMI=34.2 kg/m2) and largely sedentary (M accelerometer measured PA=19.6 min/day). Self-reported PA was measured by the International Physical Activity Questionnaire (IPAQ) long form and objectively measured PA was collected using an accelerometer at baseline (T1) and post intervention (T2). Neighborhood safety and attractiveness were measured by trained observers using the Pedestrian Environment Data Scan (PEDS). Results: At T1, African American women did more moderate intensity PA (M=24.3 vs. 10.9 minutes of moderate PA per day) and reported doing more walking (M=867.7 vs. 432.2 MET-minutes per day) than Hispanic or Latina women. At T2, African American still did more PA than Hispanic or Latina women (M=25.0 vs. 11.7 minutes of moderate PA per day), but there were no differences in self-reported PA. Bivariate associations showed that as safety (r=-0.144) and attractiveness (r=-0.149) for bicycling increased, self-reported walking decreased (ps\u3c0.05). Linear regression analyses indicated attractiveness for bicycling predicted increased T2 accelerometer measured PA (p=0.025), after adjusting for ethnicity, site, socioeconomic status (SES) and age. Conclusions: Neighborhood safety and attractiveness may influence PA. Community leaders and policy makers should consider the relationship between the built environment, PA and obesity in communities where African American and Hispanic or Latina reside when passing and/or enforcing public policies and amendments

A Comparison of the Effect of Intermittent and Continuous Infusion of Meropenem on the Prevalence of Nausea in Pediatric Cystic Fibrosis Patients

Cystic Fibrosis (CF) is a genetic disease, leading to changes of membrane secretions causing obstruction of smaller airways. CF patients often develop pulmonary infections and require antibiotic treatment. Meropenem is a broad spectrum beta lactam that acts by lysing microbes through interfering with bacterial cell wall synthesis. Although a safe and effective treatment, data on pediatric patients is limited