Level Of System Complexity Research Articles

Microarray-based characterization of differential gene expression during vocal fold wound healing in rats.

The vocal fold (VF) mucosa confers elegant biomechanical function for voice production but is susceptible to scar formation following injury. Current understanding of VF wound healing is hindered by a paucity of data and is therefore often generalized from research conducted in skin and other mucosal systems. Here, using a previously validated rat injury model, expression microarray technology and an empirical Bayes analysis approach, we generated a VF-specific transcriptome dataset to better capture the system-level complexity of wound healing in this specialized tissue. We measured differential gene expression at 3, 14 and 60 days post-injury compared to experimentally naïve controls, pursued functional enrichment analyses to refine and add greater biological definition to the previously proposed temporal phases of VF wound healing, and validated the expression and localization of a subset of previously unidentified repair- and regeneration-related genes at the protein level. Our microarray dataset is a resource for the wider research community and has the potential to stimulate new hypotheses and avenues of investigation, improve biological and mechanistic insight, and accelerate the identification of novel therapeutic targets.

Architecture as a strategy for reduced energy consumption? An in-depth analysis of residential practices’ influence on the energy performance of passive houses

Purpose – The purpose of this paper is to discuss how architectural solutions may influence residential practice and energy consumption. Design/methodology/approach – The paper is part of a larger study based on qualitative investigations of six energy-efficient housing projects in Norway. Here, the authors examine one of these projects, Løvåshagen in Bergen, the first Norwegian passive house flat building. Based on a combination of 14 interviews with household members and energy consumption data for all flats, the authors show how residential practices influence energy consumption. In the discussion and conclusion, the authors focus on the role of the architecture in these practices. Findings – On the one hand, Løvåshagen reflects a mainstreaming approach to sustainable building, attracting a wide array of different occupants. On the other hand, the specific add-ons that are intended to make the buildings energy efficient require new definitions of comfort and new skills to achieve the promised energy savings. This combination can explain why Løvåshagen, after four years of occupation, has a large variation in actual energy consumption. Practical implications – In designing new energy-efficient housing, greater attention should be paid to the level of end-user control and adaptability, the level of system complexity, and the need for adequate information. An alternative to the mainstreaming approach would be to actively use architecture to influence residential practices towards reduced energy consumption. Originality/value – The use of qualitative methods to analyse quantitative energy data is original and provides promising opportunities to understand the significance of residential practices regarding actual energy consumption.

A 0.18-$\mu$m CMOS SoC for a 100-m-Range 10-Frame/s 200$\,\times\,$96-Pixel Time-of-Flight Depth Sensor

With the emerging need for high-resolution light detection and ranging (LIDAR) technologies in advanced driver assistance systems (ADAS), we introduce a system-on-a-chip (SoC) that performs time-correlated single-photon counting and complete digital signal processing for a time-of-flight (TOF) sensor. At the core of the 0.18- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu$</tex> </formula> m CMOS SoC, we utilize linear arrays of 16 TOF and 32 intensity-only macro-pixels based on single-photon avalanche diodes in an original look-ahead concept, thus acquiring active TOF and passive intensity images simultaneously. The SoC also comprises an array of circuits capable of generating precise triggers upon spatiotemporal correlation events, an array of 64 12-b time-to-digital converters, and 768 kb of SRAM memory. The SoC provides the system-level electronics with a serial and low-bit-rate digital interface for: 1) multi-echo distance; 2) distance reliability; 3) intensity; and 4) passive-only intensity, thus mitigating system-level complexity and cost. A proof-of-concept prototype that achieves depth imaging up to 100 m with a resolution of 202 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\,\times\,$</tex> </formula> 96 pixels at 10 frames/s has been implemented. Quantitative evaluation of the TOF sensor under strong solar background illuminance, i.e., 70 klux, revealed a repeatability error of 14.2 cm throughout the distance range of 100 m, thus leading to a relative precision of 0.14%. Under the same conditions, the relative nonlinearity error was 0.11%. In order to show the suitability of our approach for ADAS-related applications, experimental results in which the depth sensor was operated in typical traffic situations have also been reported.

Fractionated robotic architectures for planetary surface mobility systems

Planetary surface exploration missions are becoming increasingly complex and future missions promise to be even more ambitious than those that have occurred thus far. To deal with this complexity, this paper proposes a fractionated approach to planetary surface exploration. Fractionation involves splitting up large vehicles into several smaller ones that work together in order to achieve the science goals. It is believed that fractionation of rovers can lead to increased value delivery and productivity, as well as helping manage complexity. A science goal-driven methodology for generating a tradespace of multi-vehicle architectures in the early stages of mission design is detailed. A set of carefully designed metrics are then put forward as a way to help compare multi-vehicle architectures to each other and to the single vehicle (monolithic) equivalent. These include science value delivery, productivity, system- and vehicle-level complexity, and mass metrics. Through two Mars-based case studies, the advantages and limitations of fractionation are explored. Fractionation is found to be particularly advantageous when the science goals are broad, when there are competing requirements between goals, and when the exploration environment is particularly treacherous. Additionally, multi-vehicle systems entail simpler vehicles with lower vehicle-level complexity, lower mission risk and higher productivity over the mission duration, as well as being more easily upgradeable. On the other hand, they lead to higher system-level complexity, and can somewhat increase the overall mass of the system. Thus, through this methodology, it was demonstrated that the fractionation of planetary surface exploration systems leads to mass being traded for higher science return and lower risk during the mission, and to complexity being shifted from design complexity to operational complexity. Multi-vehicle systems involve more testing and on-board automation than single vehicles, but they also lend themselves more easily to collaboration between different agencies, and can benefit from several emergent properties that increase the overall functionality of the system.

Molecular-level understanding of WGS and reverse WGS reactions on Rh through hierarchical multiscale approach

Hierarchically combining semi-empirical methods and first-principles calculations we gain a novel and noteworthy picture of the molecular-level mechanisms that govern the water–gas-shift (WGS) and reverse water–gas-shift (r-WGS) reactions on Rh catalysts. Central to this picture is that the WGS and r-WGS follow two different dominant reaction mechanisms: WGS proceeds according to a carboxyl (COOH) mechanism, whereas r-WGS proceeds according to a redox (CO2→CO+O) mechanism.The obtained results furthermore underscore the danger of common first-principles analyses that focus on a priori selected dominant paths. Not restricted to such bias, our herein proposed hierarchical approach thus constitutes a promising avenue to properly transport and incorporate the ab initio predictive-quality to a new level of system complexity.

A 0.013 ${\hbox {mm}}^{2}$, 5 $\mu\hbox{W}$, DC-Coupled Neural Signal Acquisition IC With 0.5 V Supply

We present an area-efficient neural signal-acquisition system that uses a digitally intensive architecture to reduce system area and enable operation from a 0.5 V supply. The architecture replaces ac coupling capacitors and analog filters with a dual mixed-signal servo loop, which allows simultaneous digitization of the action and local field potentials. A noise-efficient DAC topology and an compact, boxcar sampling ADC are used to cancel input offset and prevent noise folding while enabling “per-pixel” digitization, alleviating system-level complexity. Implemented in a 65 nm CMOS process, the prototype occupies 0.013 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> while consuming 5 μW and achieving 4.9 μVrms of input-referred noise in a 10 kHz bandwidth.

Assessment of system level complexity: Practicality at the bedside

Assessment of system level complexity: Practicality at the bedside

Agent-based organizational structures for ambient intelligence scenarios

In a society where Information and Communication Technology (ICT) becomes a key component to improve the quality of our daily-life, systems' complexity dramatically increases to better accommodate to an inherent complexity of users' requirements, especially when dealing with pervasive computing. This poses demanding architectural requirements such as massive decentralization and disintermediation along with self-organizing properties. This higher level of system complexity has triggered the birth of several software engineering methodologies that adopt the agent paradigm. Design patterns are a well known approach for capturing and reusing knowledge related to known solution for recurrent architectural problems. Even though the importance of patterns is growing as systems become more and more complex, their development does not keep up with the evolving requirements, as traditional agent patterns are unable to support the majority of current complex social scenarios. This work motivates the need for new agent-based organizational structures that are more flexible than traditional agent patterns such as, Broker and Matchmaker. The newly suggested structure supports the dynamic nature of “Active Environment” where groups of agents are formed for service delivery and then dissolved with no central coordinating mechanism—i.e., gaining the disintermediation property. Serving as a case study, the PEACH and PIL projects have paved the way for experimenting with the new agent-based organizational structures that are more flexible and more suitable than traditional agent patterns for coping with ambient intelligence scenarios.

Intercellular Coupling Confers Robustness against Mutations in the SCN Circadian Clock Network

Molecular mechanisms of the mammalian circadian clock have been studied primarily by genetic perturbation and behavioral analysis. Here, we used bioluminescence imaging to monitor Per2 gene expression in tissues and cells from clock mutant mice. We discovered that Per1 and Cry1 are required for sustained rhythms in peripheral tissues and cells, and in neurons dissociated from the suprachiasmatic nuclei (SCN). Per2 is also required for sustained rhythms, whereas Cry2 and Per3 deficiencies cause only period length defects. However, oscillator network interactions in the SCN can compensate for Per1 or Cry1 deficiency, preserving sustained rhythmicity in mutant SCN slices and behavior. Thus, behavior does not necessarily reflect cell-autonomous clock phenotypes. Our studies reveal previously unappreciated requirements for Per1, Per2, and Cry1 in sustaining cellular circadian rhythmicity and demonstrate that SCN intercellular coupling is essential not only to synchronize component cellular oscillators but also for robustness against genetic perturbations.

The Effect of Heterogeneous Displays, Awareness Tools and Audio-Chat Communication on Team Collaboration

Advances in technology and connectivity have led to the development of sophisticated portable devices incorporating functional versatility and reduced sizes. Such devices add another level of complexity in systems which are designed to support communication and collaborative work. This study researched potential problems that arise when map-reading tasks were assigned to teams of two using various modalities of communication coupled with different display sizes and interface tools. Ninety-six participants, 6 pairs in 8 conditions, performed the experiment. Results indicate that large-large screen participants were more accurate than large-small screen size and took less time than small-small screen size in the audio condition. Chat participants took longer than audio participants in the large-small screen condition. The highlighter was most frequently used in the large-large screen condition and the pointer was most frequently used in the large-small screen condition.

Civilisational Models of Politogenesis ed. by Dmitri M. Bondarenko, Andrey V. Korotayev (review)

611 Ab Imperio, 3/2004 to historical information. See, for instance, entries on Bokhara (pp. 40-42); Schahrokh, or present day Khojand (pp. 80-83); Otrar (p. 74) and Turkestan (pp. 95-97). Conspicuously missing is an entry on Samarkand. The present selection also offers entries on Tatar, Turk, Turkestani, Turkmen, and Uzbek nations. This publication has a largely symbolic value, for it was designed to commemorate a historic contribution and to mark the establishment of scholarly exchanges between French and Central Asian academics . In the preface, Vincent Fourniau points out that Central Asia remains a region not fully accessed or explored by Europeans; this situation is aggravated further by the fact that only few know about similar works in Central Asia. With the emergence of a new generation of French and other European researchers on CentralAsia, the rising need to bring these people closer has made it necessary to have a greater exchange of knowledge and ideas. This volume would have enriched its academic value had the project attracted regional scholars to offer their impressions and evaluations about French and European contributions and their impact toward understanding Central Asia. Emilian KAVALSKI Dmitri M. Bondarenko and Andrey V. Korotayev (Eds.), Civilisational Models of Politogenesis (Moscow : Russian Academy of Sciences, 2000). 318 p. ISBN 5-201-05100-6. Increasingly researchers tend to heed and adopt what are perceived as “non-western” approaches. In its current form, this inclination has been spurred by Samuel Huntington ’s memorable provocation.1 In a similar fashion, although in a much more sophisticated and judicious manner, this suggestion has been elaborated recently by the venerable Donald Puchala.2 Thereby, one is tempted to gauge the gumption of the volume edited by Dmitry Bondarenko and Andrey Korotayev along the lines of this intellectual tradition. Civilisational Models of Politogenesis shares many of the features of this literature, especially in its presentation of views of “subaltern ” and “marginalized” groups. However, the volume indicates a number of methodological problems : mainly it fails to present a convincing structure for the discussion of its topic and as a result undertakes a markedly unqualified approachdriven , rather than problem-driven research. This shortcoming effec1 S. Huntington. The Clash of Civilisations // Foreign Affairs. 1993. Vol. 72. Pp. 22-49. 2 D. Puchala. Theory and History in International Relations. New York, 2003. 612 Рецензии/Reviews tively prevents Civilisational Models of Politogenesis to ask some of the main questions at the center of its analysis: how do individuals organize themselves in social groups? How do they establish control and power-relations? How is compliance with social rules achieved? The bulk of those deficiencies stems from the theoretical section of the volume, comprising the first three chapters. In their introduction , Bondarenko and Korotayev explain that the term “politogenesis” defines not merely the process of state-formation, but the dynamics of production of “complex political organization” (pp. 16-17). However, this elaboration is obscured by the subsequent analysis, which fails to indicate the significance of such a distinction. The contradiction is made apparent in the chapter by Denis Vorobyov, who proffers the understanding that politogenesis suggests not only the formation (as the editors insist), but also the “change and development of a society ’s political structure”, which “is also possible” on the “stateless” level (p. 157). As the volume makes apparent, the aim of the editors and most of the contributors is not so much to study “politogenesis”, but rather to unpack the notion of statehood and suggest the exegetical value of non-state-centric research. Regrettably, in their attempt they have been let down by their method. As Bondarenko and Korotayev indicate , the volume adopts an evolutionary process-tracing approach to the achievement of the “same level of system complexity through different pathways of evolution, which appeared simultaneously” (p. 5). Marina Butovskaya engages in this mode of analysis in her chapter on the “biosocial preconditions for socio-political alternativity” (p. 35). In effect what she attempts is a re-conceptualization of the “socioecological ” perspective of human organization as an outcome of the patterns of relations existing among primates. Thereby, Butovskaya claims that “social relationships are outcomes of ecological pressures on individuals” (p. 36). Such an assertion is perhaps refreshing...

Effects of drought on fish across axes of space, time and ecological complexity

SummaryWe evaluate the position of 50 previously published studies of fish and drought with respect to spatial scale of study (individual stream pools to subcontinents), length of the dry period (weeks to centuries), and level of system complexity (individual fish to ecosystems). Most papers address short (months to a year) droughts or dry periods, in local reaches of streams, and impacts on populations or local assemblages. In these 50 papers, the most frequently demonstrated effects of drought were population declines, loss of habitat, changes in the community, negative effects from changes in water quality, movement within catchments, and crowding of fish in reduced microhabitats. Thirteen other less frequent effects also were identified.Gaps in knowledge exist on effects of long‐term droughts (decades to centuries), influence of drought on fish effects in ecosystems, and at the spatial scale of river basins to subcontinents. However, some of these gaps have recently been addressed, particularly additive effects of repeated drying episodes and whole‐lake or basin‐wide effects of drought, and in using molecular techniques to seek signals of drought at wide geographic scales because of events in the deep past. Gaps in knowledge remain for effects of very short dry periods, on drought effects on higher levels of complexity, and on the manner in which droughts at the scale of decades affect fish.Data from streams in Oklahoma and elsewhere in the south‐western U.S.A. suggest that most droughts may leave little persistent signal in the existing fish fauna, i.e. that recovery from drought by fish populations or assemblages in the region can be rapid. However, species that are vulnerable to drought or water loss in streams may have disappeared from some basins in the region before the mid‐1900s, and recent evidence also suggests that extreme droughts do sometimes alter fish assemblages.Little is known about mechanisms by which droughts have direct or indirect effects on fish, the roles of droughts in the evolution of fish species, and the ways droughts alter effects of fish in ecosystems. Global climate changes may have serious consequences for future local or regional fish faunas, but ongoing studies of fish experiencing drought may aid in future conservation of what will become species at risk under climate‐change scenarios.

One Size Does Not Fit All Projects: Exploring Classical Contingency Domains

Not many authors have attempted to classify projects according to any specific scheme, and those who have tried rarely offered extensive empirical evidence. From a theoretical perspective, a traditional distinction between radical and incremental innovation has often been used in the literature of innovation, and has created the basis for many classical contingency studies. Similar concepts, however, did not become standard in the literature of projects, and it seems that theory development in project management is still in its early years. As a result, most project management literature still assumes that all projects are fundamentally similar and that “one size fits all.” The purpose of this exploratory research is to show how different types of projects are managed in different ways, and to explore the domain of traditional contingency theory in the more modern world of projects. This two-step research is using a combination of qualitative and quantitative methods and two data sets to suggest a conceptual, two-dimensional construct model for the classification of technical projects and for the investigation of project contingencies. Within this framework, projects are classified into four levels of technological uncertainty, and into three levels of system complexity, according to a hierarchy of systems and subsystems. The study provides two types of implications. For project leadership it shows why and how management should adapt a more project-specific style. For theory development, it offers a collection of insights that seem relevant to the world of projects as temporary organizations, but are, at times, different from classical structural contingency theory paradigms in enduring organizations. While still exploratory in nature, this study attempts to suggest new inroads to the future study of modern project domains.

Computational experiments using distributed tools in a web-based electronic notebook environment

Scientific computational environments should provide high-level support for the integrated and systematic use of tools familiar in the laboratory setting, including lab notebooks, instruments, experiments, and analysis tools. Further, they should shield the user from the complexities of the underlying computational platform. We report here on the Virtual Notebook Environment, ViNE, which provides the web-based equivalent of the standard (paper) lab notebook, adding features for sharing, security, and collaboration. More significantly, ViNE allows scientists to represent, manage, and execute computational experiments that involve the sequenced use of data, computational tools, and programs distributed across the World Wide Web. ViNE hides system-level complexities, freeing the scientist from concerns about inter-tool connectivity, data distribution, data management, and machine idiosyncrasies. It thus extends the notebook abstraction to support a broad range of scientific computational activities in a uniform manner.

Information Technology Research

In a recent editorial ( Science 's Compass, 6 Aug., p, [833][1]), D. Allan Bromley comments on “appropriate” information technology (IT) research. I agree fully with the importance he attaches to fundamental research and to continued support of basic sciences that would lead to new advances that would have an impact on IT. However, contrary to some of his comments, that is also what the President's Information Technology Advisory Committee (PITAC) report recommended. That committee simply had a different (broader and, I believe, sounder) view of basic IT research than what Bromley presents. Bromley draws far too narrow a boundary around the sciences that are basic to research in IT, identifying them largely with the physical sciences underlying IT hardware. Without denigrating the importance of continuing development of faster and more reliable hardware, I believe that the most critical and fundamental research questions in IT for the coming decades, as PITAC argued correctly, concern the basic principles of the organization of complex information-processing systems, at both hardware and software levels. These are not primarily physical-science problems, but arise wherever high levels of system complexity are found. These organizational problems are, for example, central to understanding the evolution of biological systems and adaptive and learning systems in general, including IT systems. There is a whole history of disaster in IT research that ignored such organizational problems (for example, research on the design of parallel general-purpose systems), and the computer industry lagged for decades in recognizing the importance of relevant basic software research. Theory and design of the organization of both hardware and software are crucial to the success of the enormous, highly decentralized systems that are already becoming an integral part of our whole industrial, governmental, military, and social communication structure and which are today given real-world tasks that are way beyond their capabilities for rapid, accurate, intelligent, and safe performance. Bromley is mistaken in saying that House bill H.R. 2086 is simply supporting competitive industries. Solutions to fundamental software problems of designing ultra-complex systems are extremely important for the future security and competitiveness of the nation, they are not of burning interest to industry today, and they are largely pursued in universities. The PITAC report also recommended a study of the social implications of IT. These equally basic and important research problems must also be addressed vigorously by the public sector. [1]: /lookup/doi/10.1126/science.285.5429.833

Minimum drift architectures for 3-layer scalable DTV decoding

This paper describes new techniques for implementing a low-cost video decoder that can decode an HDTV bitstream and display the signal at lower resolutions. Two key algorithms are discussed: downconversion and low-resolution motion compensation. In the proposed scheme, incoming blocks are subject to a down-conversion process within the decoding loop, hence motion compensation is performed from the downconverted images. The filters used for down-conversion are based on the concept of frequency synthesis, and the filters used to perform the low-resolution motion compensation are determined by an optimal least squares solution. Using these algorithms, three different architectures that provide equal quality with varying system level complexity are presented; the first is directly derived from the initial model of the low-resolution decoder, another attempts to reduce the amount of computation for the IDCT, while another addresses the concerns regarding the amount of interface with an existing decoder structure. All of the above systems are hierarchical with regard to the logic used for filtering and scalable in the amount of memory which is required to reconstruct each output layer. Our simulation results demonstrate that high quality video can be provided at lower-resolutions with significant memory savings.

Reliable online human signature verification systems

Online dynamic signature verification systems were designed and tested. A database of more than 10,000 signatures in (x(t), y(t))-form was acquired using a graphics tablet. We extracted a 42-parameter feature set at first, and advanced to a set of 49 normalized features that tolerate inconsistencies in genuine signatures while retaining the power to discriminate against forgeries. We studied algorithms for selecting and perhaps orthogonalizing features in accordance with the availability of training data and the level of system complexity. For decision making we studied several classifiers types. A modified version of our majority classifier yielded 2.5% equal error rate and, more importantly, an asymptotic performance of 7% false acceptance rate at zero false rejection rate, was robust to the speed of genuine signatures, and used only 15 parameter features.

The effects of feedback on performance and retention of skill for a natural language interface

Abstract This study investigated the effectiveness of different types of on-line feedback following user errors for informing users of the information and functions available in a system with a natural language interface. Twenty-four individuals performed a task based on an industry cost savings program, in which they were given general goals to pursue with regard to the task. Three feedback levels which differed according to the type and amount of feedback provided, along with two levels of system complexity, were examined. In addition, subjects performed the task again after one week to determine the effects of feedback on retention. Results indicated that the subjects in the second level of feedback generally performed better with respect to accessing system functions and information than those in the first level. Although there was some performance improvement from the second to third level, it was not significant. However, the third level of feedback did significantly improve the efficiency with whic...

Multidisciplinary Research and Sustainable Agriculture

ABSTRACT Multidisciplinary research takes many forms, according to how strongly the disciplines interact and whether the purpose is to address a broader question or to get a better answer to the original question. The appropriate type depends on the purpose of the research, such as developing a new technique, identifying farmers' innovations that deserve further attention, evaluating a production system, or discovering principles on which future systems can be based. Although sustainable agriculture has many characteristics that make multidisciplinary research particularly appropriate, this does not rule out an important role for a single-discipline research. Nor does it imply that multidisciplinary approaches are not also suitable for many other research areas. Some people regard multidisciplinarity as essential for sustainable agriculture research because they consider that prevailing scientific thought is too dominated by reductionism and too lacking in imagination to deal with system-level complexities, especially those that seem to defy common sense. However, we can see from the evolution of several areas of physics, induding quantum mechanics, relativity theory and statistical mechanics, that even within the confines of a single discipline, scientific thought need not be exclusively reductionist and that it can deal with complex, large-scale phenomena even if their behavior is extremely counterintuitive.

Assessing an Office Chemistry Instrument

Selection of appropriate testing systems depends on the characteristics and needs of the office. Clinical practice needs, work flow needs, and the analyst's ability must be balanced against the level of system complexity, automation, quality characteristics, and cost.