Activity modulation and allosteric control of a scaffolded DNAzyme using a dynamic DNA nanostructure.

Recognition of the fundamental importance of allosteric regulation in biology dates back to not long after its discovery in the 1960s. Our ability to rationally engineer this potentially useful property into normally non-allosteric catalysts, however, remains limited. In response we report a DNA nanotechnology-enabled approach for introducing allostery into catalytic nucleic acids. Specifically, we have grafted one or two copies of a peroxidase-like DNAzyme, hemin-bound G-quadruplex (hemin-G), onto a DNA tetrahedral nanostructure in such a manner as to cause them to interact, modulating their catalytic activity. We achieve allosteric regulation of these catalysts by incorporating dynamically responsive oligonucleotides that respond to specific "effector" molecules (complementary oligonucleotides or small molecules), altering the spacing between the catalytic sites and thus regulating their activity. This designable approach thus enables subtle allosteric modulation in DNAzymes that is potentially of use for nanomedicine and nanomachines

Extraction of pure components from overlapped signals in gas chromatography-mass spectrometry (GC-MS)

Gas chromatography-mass spectrometry (GC-MS) is a widely used analytical technique for the identification and quantification of trace chemicals in complex mixtures. When complex samples are analyzed by GC-MS it is common to observe co-elution of two or more components, resulting in an overlap of signal peaks observed in the total ion chromatogram. In such situations manual signal analysis is often the most reliable means for the extraction of pure component signals; however, a systematic manual analysis over a number of samples is both tedious and prone to error. In the past 30 years a number of computational approaches were proposed to assist in the process of the extraction of pure signals from co-eluting GC-MS components. This includes empirical methods, comparison with library spectra, eigenvalue analysis, regression and others. However, to date no approach has been recognized as best, nor accepted as standard. This situation hampers general GC-MS capabilities, and in particular has implications for the development of robust, high-throughput GC-MS analytical protocols required in metabolic profiling and biomarker discovery. Here we first discuss the nature of GC-MS data, and then review some of the approaches proposed for the extraction of pure signals from co-eluting components. We summarize and classify different approaches to this problem, and examine why so many approaches proposed in the past have failed to live up to their full promise. Finally, we give some thoughts on the future developments in this field, and suggest that the progress in general computing capabilities attained in the past two decades has opened new horizons for tackling this important problem

An experimental study of the use and effects of hypertext-based explanations in knowledge-based systems

Since MYCIN, explanation has become a fundamental feature of knowledge-based systems (KBS). Among the common deficiencies of KBS explanations, the most acute one is the lack of knowledge. This dissertation research investigates the use of explanations provided with hypertext for increasing the availability and accessibility of domain knowledge. The ultimate objective is to determine the behavioral and cognitive basis of the use of hypertext in providing KBS explanations. Two informationally equivalent KBS were comparatively studied in a laboratory setting: one used hypertext to provide explanations, while the other one used conventional lineartext. The experiment involved 26 experienced professionals, and 29 undergraduate and graduate students specializing in accounting. Subjects used the experimental KBS to work on a realistic problem of financial analysis. Both the process and outcomes of explanation use were assessed. Outcome variables included improvement in decision accuracy, trust in the KBS, and perceived usefulness of explanations. In addition to questionnaires used to measure decision accuracy and perceptions, computer logs were used to capture the number, type, and context of explanation use. Thinkingaloud procedures were used to assess the nature of explanation use. Results indicate that the use of hypertext for providing explanations significantly improved decision accuracy, and influenced users' preference for explanation types, and the number and context of explanation requests. Enhanced accessibility to deep explanations via the use of hypertext significantly increased the number of deep explanations requested by both novices and experts. Verbal protocol analysis shows that the lack of knowledge and means of accessing deep explanations could make it difficult to understand KBS recommendations, and that deep explanations could improve the understandability of KBS advice, especially in cases where unfamiliar domain concepts were involved. In the hypertext group, about 37% of the deep explanations were requested in the context of judgment making, rather than in the abstract. While only about 28% of the deep explanations requested by the lineartext group were the How type, 42% were the How type for the hypertext group. Experts and novices had different preferences for explanation types. Experts requested a much higher percentage of How, and lower percentages of Why and Strategic explanations, than novices. Verbal protocol analysis illustrates that experts and novices used explanations for different purposes.Business, Sauder School ofManagement Information Systems, Division ofGraduat

Facilitating Transactions on a Crowdsourcing Platform: A Cognitive Frame Perspective

Whereas prior studies have examined crowdsourcing platforms’ function as transforming distant search into local search, exactly how to do so remains unclear. Drawing upon the cognitive frame theory as the theoretical lens, we conducted an exploratory case study on Z Inc. (pseudonym), which was one of the largest labor-market crowdsourcing platforms in the world. Despite the challenges for matchmaking between seekers and vendors of creative design, known as “the most difficult business in the world” to Z Inc. staff, the platform has made remarkable progress. A three-phase process model is inductively developed consisting of frame preparation, negotiation, and consolidation. The model reveals the underlining matchmaking mechanisms in each phase, such as building a common lexicon and coaching in the frame preparation phase. These findings contribute to both the crowdsourcing literature and cognitive frame theory, with practical implications for managing crowdsourcing platforms

“Bei Dou” Shining: Preliminary Exploration on the Development “Dao” of China’s Satellite Navigation Industry

 In recent years, China has been able to adopt a state-led national strategy for using BeiDou domestically, while expanding its global reach through a market-driven approach. The development of global navigation satellite systems (GNSS) has become an important part of the "One Belt and One Road" Initiative, and it is an important measure to deepen the strategic partnership between China and the Arab world and to realize the "mutual connectivity and communication" between the two sides. This paper attempts to analyze the structural features of China's frontier technology strategy and its impact on the global influence of China. The authors use BeiDou as a case study to analyze the structural features of China's frontier technology strategy and its impact on its global influence. The paper will show that China has achieved a high-tech innovation strategy for the development of the navigation satellite system (BDS)

Enhancing explanations in knowledge-based systems with hypertext

This article investigates the use of hypertext to enhance explanations in knowledge-based systems (KBS). Three fundamental issues are addressed: (1) why is hypertext suited for enhancing explanations in KBS? (2) what kind of knowledge needs to be added to KBS to provide effective explanations? and (3) how should such knowledge be represented efficiently and made accessible naturally and conveniently to users? The central idea is to develop a hypertext deep knowledge base to supplement KBS conclusions and explanations, so that users are provided with a rich context for understanding and interpreting KBS conclusions and reasoning. Explanations in KBS can be made more intelligible and relevant to users, and more interactive by (1) representing deep knowledge needed for explanations with hypertext in a way consistent with learning and educational theories, and (2) providing access to domain knowledge from KBS output with hypertext links, thus integrating domain knowledge into the KBS output in a manner conducive to contextualized learning

Use of hypertext to provide explanations in knowledge-based systems: A conceptual model and an implementation

This paper discusses how hypertext can be used to provide explanations in knowledge-based systems (KBS), from both conceptual and implementation perspectives. To this end, it proposes a generic approach to providing hypertext-based explanations, which is based on the functional match between hypertext and explanations in KBS. A simulated KBS for financial analysis (Hyper-FINALYZER) is also described, to demonstrate the approach. First, deep knowledge can be linked to KBS output with referential links. Second, various concepts and procedures involved in problem solving can be linked to each other with both referential links and organizational links to reflect the interdependence among domain constructs and the complexity of the task domain

The Influence of Data Analytics Capabilities on Organizational Performance: The Mediating Role of Exploitative and Exploratory Innovation

This study empirically investigates the impact of data analytics capabilities (DAC) on organizational performance, and the moderating role of exploitative and exploratory innovation. Based on a slightly revised Delphi study and interviews, this study specifies DAC as a second-order reflective-formative construct, consisting of four first-order constructs such as data collection ability, analytical ability, business knowledge of the IT department, and analytics maturity. As a result, a 15-item scale is developed for DAC. This study plans to test the hypothesized main effect and moderating relationships with a survey of business and IT managers in matched pairs. This study is expected to contribute to the literature in the following two ways: First, the empirical results will shed new light on whether and when DAC can enhance organizational performance (i.e., operational excellence, customer satisfaction, financial returns). Second, the specification and newly developed measure of DAC can facilitate future empirical research related to DAC

Curved Polycyclic Aromatic Molecules That Are π‑Isoelectronic to Hexabenzocoronene

Reported here are two types of curved π-molecules that are π-isoelectronic to planar hexabenzocoronene (HBC) but are forced out of planarity either by an embedded seven-membered ring or by atom crowding at the fjord region. Embedding a heptagon in HBC leads to a novel saddle-shaped molecule <b>1</b>, whose π-backbone is slightly less curved than the previously reported [7]­circulene in terms of the average Gauss curvature, but surprisingly much more rigid than [7]­circulene. Overcrowded fjord regions in novel derivatives of hexabenzoperylene (HBP) <b>2a</b>,<b>b</b> lead to both chiral twisted and antifolded conformers. The successful synthesis of <b>1</b> and <b>2a</b>,<b>b</b> is related to introducing alkoxyl groups to unprecedented positions of hexaphenylbenzenes. It is found that the red twisted isomer of <b>2b</b> isomerizes at elevated temperature to the yellow <i>anti</i>-folded conformer. This finding along with the study on the thermodynamics and kinetics of the thermal isomerization has improved the early understandings on the conformation of HBP. In the crystals, <b>1</b> lacks π–π interactions between neighboring molecules, while twisted-<b>2a</b> exhibits both face-to-face and edge-to-face π–π interactions. Twisted-<b>2b</b> is found to function as a p-type semiconductor in thin film transistors, but the thin films of <b>1</b> appear insulating presumably due to lacking π–π interactions. By exploring three different types of curvatures in <b>1</b> and the two isomers of <b>2b</b>, this study has revealed that the curvature of π-face plays a role in determining the frontier molecular orbital energy levels and π–π interactions and thus needs to be considered when one designs new organic semiconductors

Curved Polycyclic Aromatic Molecules That Are π‑Isoelectronic to Hexabenzocoronene

Reported here are two types of curved π-molecules that are π-isoelectronic to planar hexabenzocoronene (HBC) but are forced out of planarity either by an embedded seven-membered ring or by atom crowding at the fjord region. Embedding a heptagon in HBC leads to a novel saddle-shaped molecule <b>1</b>, whose π-backbone is slightly less curved than the previously reported [7]­circulene in terms of the average Gauss curvature, but surprisingly much more rigid than [7]­circulene. Overcrowded fjord regions in novel derivatives of hexabenzoperylene (HBP) <b>2a</b>,<b>b</b> lead to both chiral twisted and antifolded conformers. The successful synthesis of <b>1</b> and <b>2a</b>,<b>b</b> is related to introducing alkoxyl groups to unprecedented positions of hexaphenylbenzenes. It is found that the red twisted isomer of <b>2b</b> isomerizes at elevated temperature to the yellow <i>anti</i>-folded conformer. This finding along with the study on the thermodynamics and kinetics of the thermal isomerization has improved the early understandings on the conformation of HBP. In the crystals, <b>1</b> lacks π–π interactions between neighboring molecules, while twisted-<b>2a</b> exhibits both face-to-face and edge-to-face π–π interactions. Twisted-<b>2b</b> is found to function as a p-type semiconductor in thin film transistors, but the thin films of <b>1</b> appear insulating presumably due to lacking π–π interactions. By exploring three different types of curvatures in <b>1</b> and the two isomers of <b>2b</b>, this study has revealed that the curvature of π-face plays a role in determining the frontier molecular orbital energy levels and π–π interactions and thus needs to be considered when one designs new organic semiconductors