Orchestrating semiotic resources in explicit strategy instruction

Research and pedagogical information provided to teachers on implementing explicit strategy instruction has primarily focused on teachers’ speech, with limited attention to other modes of communication, such as gesture and artefacts. This interpretive case study investigates two teachers’ use of different semiotic resources when introducing second-grade readers to specific reading strategies. We analysed two teachers’ use of speech, gesture and artefacts in their introductory explanation of the declarative, procedural and conditional knowledge necessary to be strategic readers. The importance of this article lies in reconciling the narrow focus on what teachers say during explicit strategy instruction with the repertoire of semiotic resources that the teachers actually use to enact multimodal communication during their explanation of the strategy.     

Do Latino Youth Really Want to Get Pregnant?: Assessing Pregnancy Wantedness

Despite recent declines, Latinas bear a disproportionate burden of teen births. Understanding social, cultural, and demographic factors underlying pregnancy desire among Latino adolescents is needed to design effective teen pregnancy prevention interventions.

A questionnaire was completed by 794 Latino youth including a “pregnancy wantedness scale” (PWS) to assess attitudes toward an early pregnancy and socio-demographic variables. Regression analyses examined the association between these variables and PWS score. PWS scores for all groups were below but near the midpoint, suggesting ambivalence toward an early pregnancy. Being female, older, acculturated, using hormonal contraception, living with parents, and having an educated mother were significantly associated with lower PWS scores, but impacted youth differently depending on their sex and sexual experience. Multi-component Latino teen pregnancy prevention strategies should address behavioral and attitudinal differences based on sex and sexual experience and acknowledge the contribution of social determinants on pregnancy intentions.     

Participation patterns of Korean adolescents in school-based career exploration activities

Variations in the school-based career exploration activities of Korean high school students were examined. Data represented 5,227 Korean adolescents in Grade 11 contained in the Korean Education Longitudinal Study of 2005, a nationally representative longitudinal database administered by the Korean Educational Development Institute. Latent class analysis identified four classes or approaches reflecting some combination of school availability and student use of career-related activities, including minimal-, limited-, moderate-, and high-activity groups. Multiple-group analysis revealed that curriculum track (i.e., vocational or academic emphasis) was an important determinant in classification.     

The PS-BCJR Algorithm for Joint Frequency Synchronization and Data Decoding in TCM systems

This study proposes a per-survivor based BCJR algorthm for joint frequency synchronization and data decoding in trellis coded modulation (TCM) systems. The proposed algorithm uses two probing signals and a carrier frequency offset (CFO) tracker to calculate the modified gamma factor involved in the BCJR algorithm. To track the CFO, a state-time process recursively updates the CFO tracker using the soft-information provided by the modified gamma factor. The state-time process consists of a state-process and a time-process. The state-process takes advantage of the state-diversity in the TCM signals to choose the most probable CFO update corresponding to the state with the maximal modified gamma factor. Based on this CFO value, and in conjunction with the tentatively selected probing signals, the succeeding time-process can iteratively track the CFO using the trellis structure of the TCM signals. This study also develops a least-square-linear-fitting (LSLF) approach based on the CFO trace to dynamically adjust the step-size for the CFO tracker. Computer simulations show that unlike the conventional augmented a posteriori probability (A²P²) method having a small CFO tracking range, the proposed approach can handle a significantly larger CFO because of its ML-based CFO estimate. In addition, the proposed LSLF step-size determination ensures the PS-BCJR a higher accuracy in CFO estimation than the A²P².     

Estimation fusion of nonlinear cost functions with application to multisensory Kalman filtering

This paper focuses on four fusion algorithms for the estimation of nonlinear cost function (NCF) in a multisensory environment. In multisensory filtering and control problems, NCF represents a nonlinear multivariate functional of state variables, which can indicate useful information of the target systems for automatic control. To estimate the NCF using multisensory information, we propose one centralized and three decentralized estimation fusion algorithms. For multivariate polynomial NCFs, we propose a simple closed-form computation procedure. For general NCFs, the most popular procedure for the evaluation of their estimates is based on the unscented transformation. The effectiveness and estimation accuracy of the proposed fusion algorithms are demonstrated with theoretical and numerical examples.     

General solution to the losses estimation for multifractal traffic

In this work, we present a new approach for loss probability estimation in a single server link. We show how to get the estimates analytically once we assume multifractal input traffic. In order to make the estimation procedure numerically tractable without losing the accuracy, we propose the use of a Gaussian mixture model to represent the heavy tail distribution of modern network traffic trace. The adopted evaluation procedure is based on two performance measures: empirical traffic arrival load distribution and loss probability at connection. Extensive experimental tests validate the efficiency and accuracy of the proposed loss probability estimation approach against the results obtained by simulations with real traffic and by comparing with other multifractal approaches suggested in the literature.     

低碳发展方案编制指南(第四部分)——实现低碳增长的政策和行动之建筑行业的行动

实现低碳增长的政策和行动将对每个行业的政策和行动、政策表述、衡量标准、温室气体减排潜力以及政策和行动的成本效益进行介绍。本节介绍建筑行业的行动。建筑行业基于目标的政策有三类:新建建筑、改造现有建筑的能源和/或碳排放目标、范围广泛的自愿或协商的协议。     

Cell-cell proximity effects in multi-cell electroporation

We report a fundamental study of how the electropermeabilization of a cell is affected by nearby cells. Previous researchers studying electroporation of dense suspensions of cells have observed, both theoretically and experimentally, that such samples cannot be treated simply as collections of independent cells. However, the complexity of those systems makes quantitative modeling difficult. We studied the change in the minimum applied electric field, the threshold field, required to affect electropermeabilization of a cell due to the presence of a second cell. Experimentally, we used optical tweezers to accurately position two cells in a custom fluidic electroporation device and measured the threshold field for electropermeabilization. We also captured video of the process. In parallel, finite element simulations of the electrostatic potential distributions in our systems were generated using the 3-layer model and the contact resistance methods. Reasonably good agreement with measurements was found assuming a model in which changes in a cell''s threshold field were predicted from the calculated changes in the maximum voltage across the cell''s membrane induced by the presence of a second cell. The threshold field required to electroporate a cell is changed ∼5%–10% by a nearby, nearly touching second cell. Cells aligned parallel to the porating field shield one another. Those oriented perpendicular to the field enhance the applied field''s effect. In addition, we found that the dynamics of the electropermeabilization process are important in explaining observations for even our simple two-cell system.     

Migration and vascular lumen formation of endothelial cells in cancer cell spheroids of various sizes

We developed a microfluidic device to culture cellular spheroids of controlled sizes and suitable for live cell imaging by selective plane illumination microscopy (SPIM). We cocultured human umbilical vein endothelial cells (HUVECs) within the spheroids formed by hepatocellular carcinoma cells, and studied the distributions of the HUVECs over time. We observed that the migration of HUVECs depended on the size of spheroids. In the spheroids of ∼200 μm diameters, HUVECs migrated outwards to the edges within 48 h; while in the spheroids of ∼250 μm diameters, there was no outward migration of the HUVECs up to 72 h. In addition, we studied the effects of pro-angiogenic factors, namely, vascular endothelial growth factor (VEGF) and fibroblast growth factor (β-FGF), on the migration of HUVECs in the carcinoma cell spheroid. The outward migration of HUVECs in 200 μm spheroids was hindered by the treatment with VEGF and β-FGF. Moreover, some of the HUVECs formed hollow lumen within 72 h under VEGF and β-FGF treatment. The combination of SPIM and microfluidic devices gives high resolution in both spatial and temporal domains. The observation of HUVECs in spheroids provides us insight on tumor vascularization, an ideal disease model for drug screening and fundamental studies.     

A microfluidic platform for quantitative analysis of cancer angiogenesis and intravasation

Understanding the mechanism behind cancer metastasis is a major challenge in cancer biology. Several in vitro models have been developed to mimic a cancer microenvironment by engineering cancer–endothelial cell (EC) and cancer-stromal cell interactions. It has been challenging to realistically mimic angiogenesis, intravasation, and extravasation using macro-scale approaches but recent progress in microfluidics technology has begun to yield promising results. We present a metastasis chip that produce microvessels, where EC and stromal cells can be patterned in close proximity to tumor cells. The vessels are formed following a natural morphogenic process and have smooth boundaries with proper cell-cell junctions. The engineered microvessels are perfusable and have well-defined openings toward inlet and outlet channels. The ability to introduce cancer cells into different locations bordering to the microvessel wall allowed generation and maintenance of appropriate spatial gradients of growth factors and attractants. Cancer angiogenesis and its inhibition by anti-vascular endothelial growth factor (bevacizumab) treatment were successfully reproduced in the metastasis chip. Cancer intravasation and its modulation by treatment of tumor necrosis factor-α were also modeled. Compared to other models, the unique design of the metastasis chip that engineers a clear EC-cancer interface allows precise imaging and quantification of angiogenic response as well as tumor cell trans-endothelial migration. The metastasis chip presented here has potential applications in the investigation of fundamental cancer biology as well as in drug screening.