“想”多快，时间就多慢

正我们的宇宙是从"无"到"有"的,宇宙不可能凭空存在。"无"宇宙状态和"有"宇宙状态是宇宙的两种相互独立而又相互纠缠的存在形式。从理论上讲,"无"状态为虚量子场状态,"有"状态为实量子场状态。量子场是量子所存在的空间,     

The 2010 Benjamin Franklin medal in chemistry presented to Joanne Stubbe

For pioneering studies demonstrating that ribonucleotide reductases transform ribonucleotides into deoxyribonucleotides by an astonishing free-radical mechanism and for her unprecedented achievements in the study of complex biological systems through innovative chemical and spectroscopic methods.     

Microfluidics-based devices: New tools for studying cancer and cancer stem cell migration

Cell movement is highly sensitive to stimuli from the extracellular matrix and media. Receptors on the plasma membrane in cells can activate signal transduction pathways that change the mechanical behavior of a cell by reorganizing motion-related organelles. Cancer cells change their migration mechanisms in response to different environments more robustly than noncancer cells. Therefore, therapeutic approaches to immobilize cancer cells via inhibition of the related signal transduction pathways rely on a better understanding of cell migration mechanisms. In recent years, engineers have been working with biologists to apply microfluidics technology to study cell migration. As opposed to conventional cultures on dishes, microfluidics deals with the manipulation of fluids that are geometrically constrained to a submillimeter scale. Such small scales offer a number of advantages including cost effectiveness, low consumption of reagents, high sensitivity, high spatiotemporal resolution, and laminar flow. Therefore, microfluidics has a potential as a new platform to study cell migration. In this review, we summarized recent progress on the application of microfluidics in cancer and other cell migration researches. These studies have enhanced our understanding of cell migration and cancer invasion as well as their responses to subtle variations in their microenvironment. We hope that this review will serve as an interdisciplinary guidance for both biologists and engineers as they further develop the microfluidic toolbox toward applications in cancer research.     

A microdevice for the creation of patent, three-dimensional endothelial cell-based microcirculatory networks

Microvascular network formation is a significant and challenging goal in the engineering of large three-dimensional artificial tissue structures. We show here the development of a fully patent, 3D endothelial cell (microvascular) microfluidic network that has a single inlet and outlet, created in only 28 h in a microdevice involving fluid flow equivalent to natural vasculature. Our microdevice features a tailored "multi-rung ladder" network, a stylized mimic of an arterial-to-venous pedicle, designed to also allow for systematic and reproducible cell seeding. Immunofluorescence staining revealed a highly contiguous endothelial monolayer (human umbilical vein endothelial cells) throughout the whole network after 24 h of continuous perfusion. This network persisted for up to 72 h of culture, providing a useful template from which the effects of surface chemistry, fluid flow, and environmental conditions on the development of artificial vascular networks ex vivo may be rapidly and robustly evaluated.     

Foot strike patterns of recreational and sub-elite runners in a long-distance road race

Although the biomechanical properties of the various types of running foot strike (rearfoot, midfoot, and forefoot) have been studied extensively in the laboratory, only a few studies have attempted to quantify the frequency of running foot strike variants among runners in competitive road races. We classified the left and right foot strike patterns of 936 distance runners, most of whom would be considered of recreational or sub-elite ability, at the 10 km point of a half-marathon/marathon road race. We classified 88.9% of runners at the 10 km point as rearfoot strikers, 3.4% as midfoot strikers, 1.8% as forefoot strikers, and 5.9% of runners exhibited discrete foot strike asymmetry. Rearfoot striking was more common among our sample of mostly recreational distance runners than has been previously reported for samples of faster runners. We also compared foot strike patterns of 286 individual marathon runners between the 10 km and 32 km race locations and observed increased frequency of rearfoot striking at 32 km. A large percentage of runners switched from midfoot and forefoot foot strikes at 10 km to rearfoot strikes at 32 km. The frequency of discrete foot strike asymmetry declined from the 10 km to the 32 km location. Among marathon runners, we found no significant relationship between foot strike patterns and race times.     

The effects of formative reading assessments closely linked to classroom texts on high school reading comprehension

Older student reading of informational texts like those found in most high school classrooms continue to be a concern. College entrance exams scores attest to the fact that this age group of readers remain largely unprepared for the rigorous, discipline area reading and comprehension demands of higher education. In response to this issue content area teachers have been encouraged to teach reading skills for their subject matter. Standard reading instruction tools have included reading guides and summative reading assessments. This study sought to compare the effects of standard reading pedagogy with computerized, formative reading assessments given to students as they read. The largest publisher of high school textbooks, Pearson Prentice-Hall, and the publisher of the high school government text used in this study currently does not have in place digital, formative reading assessments tracking section by chapter section. High school seniors in nine sections of American Government under two different instructors participated in this mixed method, quasiexperimental study. Results indicate a significant difference in content comprehension with the formative assessment pedagogy. Survey and questionnaire responses suggest students thought they read better and were more motivated to read responding to computerized formative assessments (CBA’s) that closely tracked their subject matter textbooks.     

He may not be a liberal,but he plays one on TV: Imagining the ideology of president Clinton*

This study focuses on questions of knowledge and belief in terms of public assumptions about President Clinton. Data from a national survey reveal the widespread assumption that Clinton is more liberal than his record would indicate. The data suggest that while people may not structure their own beliefs along conventional ideological lines, many interpret contemporary politics in terms of broad ideological frameworks, even if those frameworks lead to misleading conclusions. Thus while Clinton's liberal side is well‐known (or correctly assumed), his conservative side is not: indeed, most respondents associate him with liberal indicators in nearly every area. This point is explored in the context of the relation between traditional indicators of political knowledge and ideological assumptions. The authors conclude by speculating how the notion of a uniformly “liberal” Clinton may have its origins in media coverage.     

When Words Collide Online: How Writing Style and Video Intensity Affect Cognitive Processing of Online News

This experiment explored how the writing style of online news, defined as inverted pyramid versus narrative, affects the cognitive processing of accompanying video clips. Forty seven participants read 4 online news stories and viewed the accompanying video clips. Results suggested that reading inverted pyramid stories may require allocation of more cognitive resources to encoding a related video clip. Recognition for story details was more accurate for stories in narrative than inverted pyramid style. Results are discussed in terms of a distinction between cognitive processing involved in “getting there” versus “being there” during exposure to online news.     

The Sinclair Effect: Comparing Ownership Influences on Bias in Local TV News Content

Sinclair Broadcast Group, the largest owner of U.S. local television stations, has received recent attention due to its apparent political lean and journalistic practices. This study compared the content and quality of national political news stories at Sinclair and non-Sinclair stations in three television markets. Results indicated evidence of a “Sinclair Effect,” whereby Sinclair-owned affiliate stories exhibited more cable news-style elements. Stations generally adhered to traditional journalistic principles, regardless of ownership, but Sinclair stations produced more stories with dramatic elements, commentary, and partisan sources.