A lossless DNA data hiding approach for data authenticity in mobile cloud based healthcare systems

We present a lossless Deoxyribonucleic Acid (DNA) sequence hiding method that can be used for ensuring authenticity of DNA sequence in the context of Mobile Cloud based healthcare systems. Hiding data within DNA sequence results in permanent information loss in DNA sequence. Therefore, providing DNA sequence authenticity using data hiding is challenging. Moreover, existing works on DNA data hiding require a reference DNA sequence data to retrieve hidden data. Hence, current methods are not blind approaches and inappropriate for ensuring authenticity of DNA sequence in the Mobile Cloud. The proposed method hides authentication data within DNA sequence, extracts authentication data, and reconstructs the DNA sequence without any loss of information. From there, our proposed approach guarantees DNA sequence authenticity and integrity in Mobile Cloud based healthcare systems. We present a security analysis of our method to show that the method is secured. We conduct several experiments to demonstrate the performance of our proposed method.     

“互联网+”对中国文化贸易创新发展的影响研究

运用SWOT分析法分析我国现阶段"互联网+文化贸易"的优势、劣势、机遇、挑战;通过构建多元回归模型并实证分析得出,互联网对中国文化贸易的发展总体呈现促进作用,但对文化产业中某些行业不具有影响或具有负影响作用。根据结果,提出进一步促进文化贸易创新发展的对策建议。     

Unique-order interpolative coding for fast querying and space-efficient indexing in information retrieval systems

This paper presents a size reduction method for the inverted file, the most suitable indexing structure for an information retrieval system (IRS). We notice that in an inverted file the document identifiers for a given word are usually clustered. While this clustering property can be used in reducing the size of the inverted file, good compression as well as fast decompression must both be available. In this paper, we present a method that can facilitate coding and decoding processes for interpolative coding using recursion elimination and loop unwinding. We call this method the unique-order interpolative coding. It can calculate the lower and upper bounds of every document identifier for a binary code without using a recursive process, hence the decompression time can be greatly reduced. Moreover, it also can exploit document identifier clustering to compress the inverted file efficiently. Compared with the other well-known compression methods, our method provides fast decoding speed and excellent compression. This method can also be used to support a self-indexing strategy. Therefore our research work in this paper provides a feasible way to build a fast and space-economical IRS.     

Enhanced electrohydrodynamic collapse of DNA due to dilute polymers

We experimentally demonstrate that addition of small, charge-neutral polymers to a buffer solution can promote compression of dilute solutions of single electrophoresing DNA. This phenomenon contrasts with the observed extension of DNA during capillary electrophoresis in dilute solutions of high molecular weight polymers. We propose these discrepancies in micron-scale DNA configurations arise from different nano-scale DNA-polymer collision events, controlled by solute polymer properties. We build upon theories previously proposed for intermolecular DNA aggregation in polymer-free solutions to develop scaling theories that describe trends seen in our data for intramolecular DNA compaction in dilute polymer solutions.     

科技园“温床”与“围城”效应对企业创新的影响研究

作为技术创造和技术转移的社会实验,建立科技园区可能成功也可能失败。本研究利用国内8个科技园内457家高技术企业的问卷调查数据,对科技园的"温床效应"、"围城效应"以及高技术企业组织战略对创新效果的调节作用进行了考察和实证检验,研究发现:科技园的"温床效应"和"围城效应"并存,而且其对创新的主效应作用明显,但是高技术企业采取合理的组织战略可以促进"温床效应"对创新的正向作用,并且合理的组织战略可以负向调节科技园"围城效应"对企业创新的抑制性作用。基于研究结论,本文也为政府相关部门和入驻科技园的高技术企业提出具有针对性的政策建议。     

Simulations of DNA stretching by flow field in microchannels with complex geometry

Recently, we have reported the experimental results of DNA stretching by flow field in three microchannels (C. H. Lee and C. C. Hsieh, Biomicrofluidics 7(1), 014109 (2013)) designed specifically for the purpose of preconditioning DNA conformation for easier stretching. The experimental results do not only demonstrate the superiority of the new devices but also provides detailed observation of DNA behavior in complex flow field that was not available before. In this study, we use Brownian dynamics-finite element method (BD-FEM) to simulate DNA behavior in these microchannels, and compare the results against the experiments. Although the hydrodynamic interaction (HI) between DNA segments and between DNA and the device boundaries was not included in the simulations, the simulation results are in fairly good agreement with the experimental data from either the aspect of the single molecule behavior or from the aspect of ensemble averaged properties. The discrepancy between the simulation and the experimental results can be explained by the neglect of HI effect in the simulations. Considering the huge savings on the computational cost from neglecting HI, we conclude that BD-FEM can be used as an efficient and economic designing tool for developing new microfluidic device for DNA manipulation.     

国际化与中国本土企业“以弱胜强”的创新战略

以中国经济高度国际化对中国本土企业创新实践的影响为出发点,在文献评述的基础上,通过科学的案例研究方法,研究了中国电信设备企业"以弱胜强"的创新战略,并讨论了这一战略对中国本土企业的普遍适用性。探索了"以弱胜强"的创新战略是国际化条件下中国本土企业生存和发展的核心问题。     

Simulation guided design of a microfluidic device for electrophoretic stretching of DNA

We have used Brownian dynamics-finite element method (BD-FEM) to guide the optimization of a microfluidic device designed to stretch DNA for gene mapping. The original design was proposed in our previous study [C. C. Hsieh and T. H. Lin, Biomicrofluidics 5(4), 044106 (2011)] for demonstrating a new pre-conditioning strategy to facilitate DNA stretching through a microcontraction using electrophoresis. In this study, we examine the efficiency of the original device for stretching DNA with different sizes ranging from 48.5 kbp (λ-DNA) to 166 kbp (T4-DNA). The efficiency of the device is found to deteriorate with increasing DNA molecular weight. The cause of the efficiency loss is determined by BD-FEM, and a modified design is proposed by drawing an analogy between an electric field and a potential flow. The modified device does not only regain the efficiency for stretching large DNA but also outperforms the original device for stretching small DNA.     

以市场换技术战略成效不佳的原因辨析及我国的对策

针对主客观多方面的原因造成我国“以市场换技术”战略成效不佳的现象,提出随着我国经济技术实力的增强,应适时调整和丰富“以市场换技术”的内涵,加强管理,增强我国研发能力,鼓励跨国公司与我国企业合作、合资设立研发机构,加强知识产权保护等措施,促进发达国家对我国的技术转移。     

Size-dependent trajectories of DNA macromolecules due to insulative dielectrophoresis in submicrometer-deep fluidic channels

In this paper, we demonstrate for the first time that insulative dielectrophoresis can induce size-dependent trajectories of DNA macromolecules. We experimentally use λ (48.5 kbp) and T4GT7 (165.6 kbp) DNA molecules flowing continuously around a sharp corner inside fluidic channels with a depth of 0.4 μm. Numerical simulation of the electrokinetic force distribution inside the channels is in qualitative agreement with our experimentally observed trajectories. We discuss a possible physical mechanism for the DNA polarization and dielectrophoresis inside confining channels, based on the observed dielectrophoresis responses due to different DNA sizes and various electric fields applied between the inlet and the outlet. The proposed physical mechanism indicates that further extensive investigations, both theoretically and experimentally, would be very useful to better elucidate the forces involved at DNA dielectrophoresis. When applied for size-based sorting of DNA molecules, our sorting method offers two major advantages compared to earlier attempts with insulative dielectrophoresis: Its continuous operation allows for high-throughput analysis, and it only requires electric field strengths as low as ∼10 V∕cm.     

Structural and dynamic properties of linker histone H1 binding to DNA

Found in all eukaryotic cells, linker histones H1 are known to bind to and rearrange nucleosomal linker DNA. In vitro, the fundamental nature of H1∕DNA interactions has attracted wide interest among research communities-from biologists to physicists. Hence, H1∕DNA binding processes and structural and dynamical information about these self-assemblies are of broad importance. Targeting a quantitative understanding of H1 induced DNA compaction mechanisms, our strategy is based on using small-angle x-ray microdiffraction in combination with microfluidics. The usage of microfluidic hydrodynamic focusing devices facilitates a microscale control of these self-assembly processes, which cannot be achieved using conventional bulk setups. In addition, the method enables time-resolved access to structure formation in situ, in particular, to transient intermediate states. The observed time dependent structure evolution shows that the H1∕DNA interaction can be described as a two-step process: an initial unspecific binding of H1 to DNA is followed by a rearrangement of molecules within the formed assemblies. The second step is most likely induced by interactions between the DNA and the H1's charged side chains. This leads to an increase in lattice spacing within the DNA∕protein assembly and induces a decrease in the correlation length of the mesophases, probably due to a local bending of the DNA.     

Modeling the relaxation time of DNA confined in a nanochannel

Using a mapping between a Rouse dumbbell model and fine-grained Monte Carlo simulations, we have computed the relaxation time of λ-DNA in a high ionic strength buffer confined in a nanochannel. The relaxation time thus obtained agrees quantitatively with experimental data [Reisner et al., Phys. Rev. Lett. 94, 196101 (2005)] using only a single O(1) fitting parameter to account for the uncertainty in model parameters. In addition to validating our mapping, this agreement supports our previous estimates of the friction coefficient of DNA confined in a nanochannel [Tree et al., Phys. Rev. Lett. 108, 228105 (2012)], which have been difficult to validate due to the lack of direct experimental data. Furthermore, the model calculation shows that as the channel size passes below approximately 100 nm (or roughly the Kuhn length of DNA) there is a dramatic drop in the relaxation time. Inasmuch as the chain friction rises with decreasing channel size, the reduction in the relaxation time can be solely attributed to the sharp decline in the fluctuations of the chain extension. Practically, the low variance in the observed DNA extension in such small channels has important implications for genome mapping.     

Technological competition and patent strategy: Protecting innovation,preempting rivals and defending the freedom to operate

Drawing on the resource-based view of the firm, we examine the effect of technological competition over a patent on the firm's choice of patenting strategy. We claim that technological competition makes the traditional strategy of protecting focal innovations from imitation less likely and increases the likelihood of a play strategy — i.e. using patents to avoid the risk of hold-up by other patent owners, or as a bargaining chip in litigation and cross-licensing. However, we claim also that technological competition over a target close to the firm's core technology should lead to use of a fence strategy i.e. to blocking the commercial endeavors of rivals and preempting substitute inventions. We find support for our hypotheses using data from a large-scale survey of European patent applications.     

Focusing and trapping of DNA molecules by head-on ac electrokinetic streaming through join asymmetric polarization

In this work, invoking join asymmetric ac polarization using double half-quadrupole electrodes in a symmetric arrangement, we demonstrate a head-on ac electro-osmotic streaming capable of focusing and trapping DNA molecules efficiently. This is manifested by the observation that picomolar DNA molecules can be trapped into a large crosslike spot with at least an order of magnitude concentration enhancement within just half a minute. We identify that the phenomenon is a combined result of the formation of two prefocused DNA jets flowing toward each other, dipole-induced attraction between focused DNA molecules, and dielectrophoretic trap on the spot. With an additional horizontal pumping, we observe that the trap can transform into a peculiar pitchfork streaming capable of continuous collection and long-distance transport of concentrated DNA molecules. We also show that the same electrode design can be used to direct assembly of submicrometer particles. This newly designed microfluidic platform not only has potentials in enhancing detection sensitivity and facilitating functional assembly for on-chip analysis but also provides an added advantage of transporting target molecules in a focused and continuous manner.     

基于pair copula-GARCH模型的多资产组合VaR分析

提出了多资产组合风险分析的pair copula-GARCH 模型.相比于以往的copula-GARCH模型,它能够更好描述投资组合中两两资产间的尾部相关性的差异,从而更好地度量多资产组合间的相依结构.在此基础上,还探讨了pair copula-GARCH 模型下的多资产线性组合的VaR的计算方法.最后给出模型的实证分析.     

Measuring follow-on innovation

How patents affect follow-on innovation is a key question for the patent system. We disaggregate follow-on innovation into activities that infringe patents and others that do not infringe but can be indirectly affected by patents. Replicating an important study using our disaggregated measure, we find that 87 percent of follow-on scientific publications describing patented genes do not constitute patent infringement. Supplementing our empirical strategy with data on patent expiration dates, we find that gene patents which are not close to expiration cause an increase in noninfringing follow-on research, but the effect disappears for patents close to expiration. Our nuanced measure helps better identify the mechanisms of patents’ effect, reconcile disparate results in the literature, and evaluate policy reform.     

Using query logs to establish vocabularies in distributed information retrieval

Users of search engines express their needs as queries, typically consisting of a small number of terms. The resulting search engine query logs are valuable resources that can be used to predict how people interact with the search system. In this paper, we introduce two novel applications of query logs, in the context of distributed information retrieval. First, we use query log terms to guide sampling from uncooperative distributed collections. We show that while our sampling strategy is at least as efficient as current methods, it consistently performs better. Second, we propose and evaluate a pruning strategy that uses query log information to eliminate terms. Our experiments show that our proposed pruning method maintains the accuracy achieved by complete indexes, while decreasing the index size by up to 60%. While such pruning may not always be desirable in practice, it provides a useful benchmark against which other pruning strategies can be measured.     

Cost-effectiveness analysis of acute kidney injury biomarkers in pediatric cardiac surgery

Introduction

Acute kidney injury (AKI) is significant problem in children with congenital heart disease (CHD) who undergo cardiac surgery. The economic impact of a biomarker-based diagnostic strategy for AKI in pediatric populations undergoing CHD surgery is unknown. The aim of this study was to perform the cost effectiveness analysis of using serum cystatin C (sCysC), urine neutrophil gelatinase-associated lipocalin (uNGAL) and urine liver fatty acid-binding protein (uL-FABP) for the diagnosis of AKI in children after cardiac surgery compared with current diagnostic method (monitoring of serum creatinine (sCr) level).

Materials and methods

We developed a decision analytical model to estimate incremental cost-effectiveness of different biomarker-based diagnostic strategies compared to current diagnostic strategy. The Markov model was created to compare the lifetime cost associated with using of sCysC, uNGAL, uL-FABP with monitoring of sCr level for the diagnosis of AKI. The utility measurement included in the analysis was quality-adjusted life years (QALY). The results of the analysis are presented as the incremental cost-effectiveness ratio (ICER).

Results

Analysed biomarker-based diagnostic strategies for AKI were cost-effective compared to current diagnostic method. However, uNGAL and sCys C strategies yielded higher costs and lower effectiveness compared to uL-FABP strategy. uL-FABP added 1.43 QALY compared to current diagnostic method at an additional cost of $8521.87 per patient. Therefore, ICER for uL-FABP compared to sCr was $5959.35/QALY.

Conclusions

Our results suggest that the use of uL-FABP would represent cost effective strategy for early diagnosis of AKI in children after cardiac surgery.Key words: acute kidney injury, cardiac surgery, children, biomarkers, cost effectiveness analysis     

经费规模与科研产出——基于NSFC资助政策“净效应”的分析

科学研究离不开稳定持续的经费投入,科学合理的科研经费配置对提高科学基金资助成效尤为重要。采用双重差分（DID）方法,对NSFC面上项目2011年资助政策变化进行分析,检验了剔除项目不相关产出后经费增加对科研产出的影响,从而验证经费变化的政策“净效应”。研究发现：科学基金经费增加显著提升了科研产出数量和质量。而剔除不相关产出考虑政策“净效应”后,经费增加对项目产出质量提升更显著。通过异质性分析发现：经费规模增加对科研产出影响的政策“净效应”存在着“强者恒强”的作用,且中等规模团队在经费增加政策中受益更多。为进一步提高科研经费配置成效,可适当增加经费规模,引导科研人员“重质而非冲量”学术发表行为;科学基金针对不同人群实行精细化、差异化资助,提高资助政策精准化程度;进一步完善科学基金成果管理,应更加关注项目的实际产出。     

Dangerous Darwinism

We are concerned with a particular rhetorical narrative that appeared in the early stages of the Darwin debate but that has been fiercely resurgent in the past two decades. Freud wrote of Darwin's theory as one of three major blows to which human vanity had been submitted at the hands of science. Assertions that "Darwin's dangerous idea" came as a horrible shock to the Victorians and that it is still a profound psychological threat, and therefore widely resisted, remain current. When such assertions are offered as the premise on which Darwin is to be approached by the general reader they call for some detailed scrutiny, with regard both to the bases on which they are made, and the effect they have on the terms of public debate. This paper offers a critique of the culture-shock myth based on a re-examination of Victorian reactions to Darwin's work, and on an analysis of the ways in which the myth functions as a rhetorical strategy in our own time.