Internet use, videogame playing and cell phone use as predictors of children’s body mass index (BMI), body weight, academic performance, and social and overall self-esteem

In this research we examined the prediction of children’s body mass index (BMI), body weight, academic performance, social self-esteem and overall self-esteem from their IT (information technology) use, specifically, their Internet use, cell phone use and videogame playing, after controlling for the effects of gender, race, age and household income on these measures. Participants were 482 children whose average age was 12 years old. One-third was African American and two-thirds were Caucasian American. Results indicated that IT use did not predict BMI or body weight, contrary to one previous survey and the widespread belief that screen time is responsible for the obesity epidemic among our nation’s children. Instead, BMI and body weight were higher for African Americans, older children and children from lower income households. The sole and strong positive predictor of visual-spatial skills was videogame playing, which also predicted lower grade point averages (GPAs). Gender and Internet use predicted standardized test scores in reading skills. Females and children who used the Internet more had better reading skills than did males and children who used the Internet less, respectively. Implications of these findings for future research on the benefits and liabilities of IT use are discussed.     

An efficient tabu search algorithm to the cell formation problem with alternative routings and machine reliability considerations

Cell formation is the first step in the design of cellular manufacturing systems. In this study, an efficient tabu search algorithm based on a similarity coefficient is proposed to solve the cell formation problem with alternative process routings and machine reliability considerations. In the proposed algorithm, good initial solutions are first generated and later on improved by a tabu search algorithm combining the mutation operator and an effective neighborhood solution searching mechanism. Computational experiences from test problems show that the proposed approach is extremely effective and efficient. When compared with the mathematical programming approach which took three hours to solve problems, the proposed algorithm is able to produce optimal solutions in less than 2 s.     

DRIE based technology for 3D silicon barcodes fabrication

Microworld barcoding has become a promising tool for cell biology. Individual and subpopulation cell tracking is of great interest to evaluate cell behaviour. Nowadays, many micrometer and even nanometer size silicon structures can be fabricated using microelectronics techniques. In this work we report for first time the development of 3D barcodes based on silicon substrate. The proposed silicon micromachining technology based on deep reactive ion etching (DRIE) allows to obtain micrometer-sized cylindrical structures with vertical etch profile that defines a bit = 1 and non-vertical etch profile that defines a bit = 0. Although this technology will allow more than 15 bits representation, only 4-8 bits are necessary for cell labelling. The results of this work show that DRIE has become a versatile technique to produce high aspect 3D biocompatible silicon-based barcodes structures for cell studies.     

Development of high throughput microfluidic cell culture chip for perfusion 3-dimensional cell culture-based chemosensitivity assay

This study reports a microfluidic cell culture chip encompassing 36 microbioreactors for high throughput perfusion 3-dimensional (3D) cell culture-based chemosensitivity assays. Its advantages include the capability for multiplexed medium delivery, and the function for both efficient and high throughput micro-scale 3D culture construct preparation and loading. The results showed that the proposed medium pumping mechanism was able to provide a uniform pumping rates ranging from 1.2 to 3.9 μl h⁻¹. In addition, the simple cell/hydrogel loading scheme has been proven to be able to carry out 3D cell culture construct preparation and loading precisely and efficiently. Furthermore, a chemosensitivity assay was successfully demonstrated using the proposed cell culture chip. The results obtained were also compared with the same evaluation based on a conventional 2D monolayer cell culture. It can be concluded that the choice of cell culture format can result in different chemosensitivity evaluation results. Overall, because of the nature of miniaturized perfusion 3D cell culture, the cell culture chip not only can provide stable, well-defined and more biologically relevant culture environments, but it also features low consumption of research resources. All these traits are found particularly useful for high-precision and high-throughput 3D cell culture-based assays.     

Surface plasmon resonance (SPR) sensors for the rapid, sensitive detection of the cellular response to osmotic stress

Cells regulate their volume in response to changes in osmolarity of both, their extracellular and intracellular environments. As stability of the cell volume is a compelling exigency for cellular integrity, techniques for a sensitive, time-resolved volume measurement of adherently grown mammalian cells attract considerable interest, especially in the field of cell physiology and biology. In this study we apply a surface plasmon resonance (SPR) based biosensor for the comparative analysis of the volume responses of two renal epithelial cell types to non-isotonic challenges. The on-line, label-free and non-invasive biosensor format shows distinct similarities and differences in the reaction kinetics of the two cell types. Furthermore regulatory volume responses to the osmotic stimuli as well as their inhibition by Gd³⁺ ions can be observed with a high time-resolution. Limit-of-detection measurements indicate the high sensitivity of the sensor capable of detecting cellular volume responses of adherently grown mammalian cells to osmotic stimuli well below a bioanalytical relevant value of 5 mOsm/kg.     

Recognition and analysis of cell nuclear phases for high-content screening based on morphological features

Automated analysis of molecular images has increasingly become an important research in computational life science. In this paper some new and efficient algorithms for recognizing and analyzing cell phases of high-content screening are presented. The conceptual frameworks are based on the morphological features of cell nuclei. The useful preprocessing includes: smooth following and linearization; extraction of morphological structural points; shape recognition based morphological structure; issue of touching cells for cell separation and reconstruction. Furthermore, the novel detecting and analyzing strategies of feed-forward and feed-back of cell phases are proposed based on gray feature, cell shape, geometrical features and difference information of corresponding neighbor frames. Experiment results tested the efficiency of the new method.     

呼叫准入约束下Macro-Femto小区选择GSPN模型研究

随着数据业务快速增长,仅靠宏蜂窝网络已无法满足流量需求;飞蜂窝网络可以有效分流宏蜂窝流量, 近年来 所构成的Macro-Femto架构得到了较广泛的部署。Macro-Femto网络部署的关键问题之一是小区选择,由于飞蜂窝网络频谱资源有限,进行小区选择时仍需考虑呼叫准入控制(Call Admission Control,CAC)。图形化的广义随机Petri网(Generalized Stochastic Petri Nets,GSPN)具有并行性、不确定性和异步特性以及强大的分析复杂系统的功能。针对Macro-Femto网络的呼叫准入约束机制,通过分析呼叫对信道的占用情形,在改进呼叫重审机制的基础上,建立了呼叫准入控制策略GSPN模型。利用建立的GSPN模型,分析了不同呼叫准入控制策略对新呼叫和切换呼叫阻塞率的影响,给出了部分重审机制的呼叫准入控制策略。在分析飞蜂窝的高速服务特性和宏蜂窝的高负载能力的基础上,结合部分重审呼叫准入策略和GSPN方法,提出了基于负载的飞蜂窝优先选择方案(Load-Based Femto-Priority Selection Scheme,LFP)。仿真结果表明,较典型的飞蜂窝优先选择方案,所提出的LFP方案对新呼叫的阻塞率和切换呼叫的掉线率分别降低了2.7%和4.6%。     

Mobile phone use among college students is a sedentary leisure behavior which may interfere with exercise

Research suggests that cell phone use is related to sedentary behavior, that cell phone use during exercise reduces intensity, and that high frequency cell phone users are less fit than other users. Thus, cell phone use appears connected to health and fitness behaviors and should be better understood within this context. The present study investigated the sedentary nature of cell phone use, and examined the likelihood of cellphone use interfering with exercise behavior.DesignA validated survey was administered to a random sample of students from a public US university (N = 226).ResultsMean self-reported cell phone use was 380 min day⁻¹, 87% reported cell phone use primarily occurs while sitting, and 70% of use was for leisure. Cell phone use was positively related to sedentary behavior (β = 0.30, p < 0.001). It was not related to physical activity. However, the likelihood of cell phone use during moderate (p = 0.006) and mild (p < 0.001) intensity exercise increased as cell phone use increased.ConclusionLike other screens (e.g., TVs), cell phone use appears to be a sedentary leisure behavior. Furthermore, high frequency use increases the likelihood that it will occur during exercise, likely lowering exercise intensity.     

基于RGD多肽掺杂聚吡咯-铟锡氧化物的仿生微电极构建及用于细胞生物学行为的电化学阻抗谱检测

构建一种基于RGD多肽分子掺杂聚吡咯膜修饰的铟锡氧化物微电极(PPy/RGD-ITO),并以此作为传感电极实现细胞生物学行为的电化学阻抗谱检测.采用光刻技术蚀刻感光干膜绝缘层制备ITO微电极;以含RGD模体的多肽分子作为吡咯电聚合唯一的掺杂阴离子,通过电化学共聚合方式在ITO微电极表面沉积PPy/RGD复合膜形成PPy/RGD-ITO微电极;原子力显微镜(AFM)、接触角测量仪和傅里叶变换红外光谱仪(FTIR)分别表征PPy/RGD复合膜的表面拓扑形貌、湿润性和组成成分;人肺癌细胞株A549铺展、粘附及增殖实验考察了PPy/RGD复合膜与细胞间的相互作用;以构建的PPy/RGD-ITO微电极作为传感电极,通过电化学阻抗谱技术对A549细胞粘附增殖行为及天然抗癌药物分子重楼皂苷I的细胞毒性进行了分析.结果显示,通过简单的电化学共聚合成功将RGD分子掺杂进PPy膜内,且PPy/RGD复合膜具有优异的表面物理性能;PPy基质膜内掺杂的RGD分子保留其生物活性,相比裸ITO电极和聚4-苯乙烯磺酸钠(PSS)掺杂的PPy膜,PPy/RGD复合膜能更好地促进A549细胞的铺展、粘附和增殖;由于PPy/RGD-ITO微电极表面A549细胞形态学变化可改变电极系统的阻抗谱特征,因此通过电化学阻抗谱技术可解析A549细胞粘附增殖行为学信息,同时可定量分析重楼皂苷I细胞毒性.因此,通过简单的电化学共聚合方法将生物活性RGD分子掺杂进PPy膜内制备出的PPy/RGD膜具有优良的生物相容性,可作为一种重要的仿生电极修饰材料用于构建电子系统和细胞生物学系统的耦合界面,未来可应用于细胞生物学行为及药物筛选研究.     

基于标准CMOS工艺太阳能电池的微电源管理系统

文章基于CMOS太阳能电池设计了一款微电源管理系统。此电源管理系统适用于传感器网络节点和半有源电子标签之类的需要周期性短时间供电的电路。电源管理系统中包含一个电荷泵,一个片外储能电容,控制电路和一个线性稳压器。控制电路采用一种全新的结构,静态功耗基本为零。采用UMC 0.18μm CMOS工艺,当输出电流为30uA,储能电容为1uF时,一个周期可达到大于20ms的供电时间,输出电压1.8V,电源管理系统的静态电流小于1.5uA。