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Complex Environment (complex + environment)
Selected AbstractsSimple Efficient Contracts in Complex EnvironmentsECONOMETRICA, Issue 3 2008Robert Evans This paper studies a general model of holdup in a setting encompassing the models of Segal (1999) and Che and Hausch (1999) among others. It is shown that if renegotiation is modeled as an infinite-horizon noncooperative bargaining game, then, with a simple initial contract, an efficient equilibrium will generally exist. The contract is robust in the sense that it does not depend on fine details of the model. The contract gives authority to one party to set the terms of trade and gives the other party a nonexpiring option to trade at these terms. The difference from standard results arises because the initial contract ensures that the renegotiation game has multiple equilibria; the multiplicity of continuation equilibria can be used to enforce efficient investment. [source] Project Development in Complex Environments: Assessing Safety in Design and Decision-MakingJOURNAL OF CONTINGENCIES AND CRISIS MANAGEMENT, Issue 3 2001Joop F. M. Koppenjan How can we be sure that safety risks are adequately dealt with in the design of complex, innovative projects? In The Netherlands, a number of recent innovative project initiatives have made this a relevant question. These initiatives include projects such as the construction of tunnels using new technologies, the construction of underground facilities that combine several functions, i.e. shopping, parking and transport, and the development of a transport corridor in which rail, road and waterway have been or will be combined. These projects combine several functions and have been, or will be, realised in densely built and populated areas. Although safety regulations for products and systems have been institutionalised through legislation and professional design practices, recent project proposals link systems and their environment in new and complex ways. The risks evolving from these links are unknown and the extent to which they are covered by existing safety approaches is uncertain. In this contribution, we examine how the attention paid to safety can be increased and maintained in the design process of infrastructural projects. First, we discuss the need to reorganise the safety focus in the design process. Then we describe the role of the design process in decision-making for major projects with regard to utility building, town planning and the construction of infrastructures. Third, we elaborate how the focus on safety can be organised within this context, given developments in the field of interactive decision-making and the design and management of interaction processes. We then outline a safety risk management method that can be used to achieve this and, finally, address the conditions that influence the use of this method. [source] Environmental complexity and central nervous system development and functionDEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 2 2004Mark H. Lewis Abstract Environmental restriction or deprivation early in development can induce social, cognitive, affective, and motor abnormalities similar to those associated with autism. Conversely, rearing animals in larger, more complex environments results in enhanced brain structure and function, including increased brain weight, dendritic branching, neurogenesis, gene expression, and improved learning and memory. Moreover, in animal models of CNS insult (e.g., gene deletion), a more complex environment has attenuated or prevented the sequelae of the insult. Of relevance is the prevention of seizures and attenuation of their neuropathological sequelae as a consequence of exposure to a more complex environment. Relatively little attention, however, has been given to the issue of sensitive periods associated with such effects, the relative importance of social versus inanimate stimulation, or the unique contribution of exercise. Our studies have examined the effects of environmental complexity on the development of the restricted, repetitive behavior commonly observed in individuals with autism. In this model, a more complex environment substantially attenuates the development of the spontaneous and persistent stereotypies observed in deer mice reared in standard laboratory cages. Our findings support a sensitive period for such effects and suggest that early enrichment may have persistent neuroprotective effects after the animal is returned to a standard cage environment. Attenuation or prevention of repetitive behavior by environmental complexity was associated with increased neuronal metabolic activity, increased dendritic spine density, and elevated neurotrophin (BDNF) levels in brain regions that are part of cortical,basal ganglia circuitry. These effects were not observed in limbic areas such as the hippocampus. MRDD Research Reviews 2004;10:91,95. © 2004 Wiley-Liss, Inc. [source] Development of Prototype Wireless Transmission Measurement for Glucose in Subcutaneous and Brain StriatumELECTROANALYSIS, Issue 9 2008Farook Ahmad Abstract Monitoring of glucose in subcutaneous and brain striatum have been extensively studied in the past. While biocompatibility was one of the limitations, others included the messy measuring equipments preclude monitoring in a complex environment. This study tried to establish an amperometric measurement of glucose in pre- and post-insulin-administration on diabetic and hyperglycemia rats via wireless. The results have indicated that the wireless sensing kit used was capable of monitoring glucose in both subcutaneous and brain. The physiological data have also shown a new insight on the fabrication of implantable glucose sensors. [source] An Epidemiologic Study of Closed Emergency Department Malpractice Claims in a National Database of Physician Malpractice InsurersACADEMIC EMERGENCY MEDICINE, Issue 5 2010Terrence W. Brown MD Abstract Objectives:, The objective was to perform an epidemiologic study of emergency department (ED) medical malpractice claims using data maintained by the Physician Insurers Association of America (PIAA), a trade association whose participating malpractice insurance carriers collectively insure over 60% of practicing physicians in the United States. Methods:, All closed malpractice claims in the PIAA database between 1985 and 2007, where an event in an ED was alleged to have caused injury to a patient 18 years of age or older, were retrospectively reviewed. Study outcomes were the frequency of claims and average indemnity payments associated with specific errors identified by the malpractice insurer, as well as associated health conditions, primary specialty groups, and injury severity. Indemnity payments include money paid to claimants as a result of settlement or court adjudication, and this financial obligation to compensate a claimant constitutes the insured's financial liability. These payments do not include the expenses associated with resolving a claim, such as attorneys' fees. The study examined claims by adjudicatory outcome, associated financial liability, and expenses of litigation. Adjudicatory outcome refers to the legal disposition of a claim as it makes its way into and through the court system and includes resolution of claims by formal verdict as well as by settlement. The study also investigated how the number of claims, average indemnity payments, paid-to-close ratios (the percentage of closed claims that resolved with a payment to the plaintiff), and litigation expenses have trended over the 23-year study period. Results:, The authors identified 11,529 claims arising from an event originating in an ED, representing over $664 million in total liability over the 23-year study period. Emergency physicians (EPs) were the primary defendants in 19% of ED claims. The largest sources of error, as identified by the individual malpractice insurer, included errors in diagnosis (37%), followed by improper performance of a procedure (17%). In 18% of claims, no error could be identified by the insurer. Acute myocardial infarction (AMI; 5%), fractures (6%), and appendicitis (2%) were the health conditions associated with the highest number of claims. Over two-thirds of claims (70%) closed without payment to the claimant. Most claims that paid out did so through settlement (29%). Only 7% of claims were resolved by verdict, and 85% of those were in favor of the clinician. Over time, the average indemnity payments and expenses of litigation, adjusted for inflation, more than doubled, while both the total number of claims and number of paid claims decreased. Conclusions:, Emergency physicians were the primary defendants in a relatively small proportion of ED claims. The disease processes associated with the highest numbers of claims included AMI, appendicitis, and fractures. The largest share of overall indemnity was attributed to errors in the diagnostic process. The financial liability of medical malpractice in the ED is substantial, yet the vast majority of claims resolve in favor of the clinician. Efforts to mitigate risk in the ED should include the diverse clinical specialties who work in this complex environment, with attention to those health conditions and potential errors with the highest risk. ACADEMIC EMERGENCY MEDICINE 2010; 17:553,560 © 2010 by the Society for Academic Emergency Medicine [source] Yeast responses to stresses associated with industrial brewery handlingFEMS MICROBIOLOGY REVIEWS, Issue 5 2007Brian R. Gibson Abstract During brewery handling, production strains of yeast must respond to fluctuations in dissolved oxygen concentration, pH, osmolarity, ethanol concentration, nutrient supply and temperature. Fermentation performance of brewing yeast strains is dependent on their ability to adapt to these changes, particularly during batch brewery fermentation which involves the recycling (repitching) of a single yeast culture (slurry) over a number of fermentations (generations). Modern practices, such as the use of high-gravity worts and preparation of dried yeast for use as an inoculum, have increased the magnitude of the stresses to which the cell is subjected. The ability of yeast to respond effectively to these conditions is essential not only for beer production but also for maintaining the fermentation fitness of yeast for use in subsequent fermentations. During brewery handling, cells inhabit a complex environment and our understanding of stress responses under such conditions is limited. The advent of techniques capable of determining genomic and proteomic changes within the cell is likely vastly to improve our knowledge of yeast stress responses during industrial brewery handling. [source] Environmental complexity affects contextual fear conditioning following hippocampal lesions in ratsHIPPOCAMPUS, Issue 5 2007Sandra N. Moses Abstract Contextual fear conditioning has become a benchmark measure for hippocampal function, even though several studies report successful acquisition in hippocampal-damaged rodents. The current study examined whether environmental complexity may account for these discrepancies. We directly compared single-session contextual fear conditioning in rats in a simple vs. complex environment. Hippocampal lesions led to reduced fear conditioning in both contexts, as measured by freezing, but the effect was significantly greater in the complex context. As well, lesions led to generalized fear when the complex context was paired with shock, but not when the simple context was paired. We suggest that the representation of the simple context formed by rats with hippocampal lesions was adequate to support associative learning, but the representation of the complex context, which depended to a greater extent on relational learning, was not. The results were interpreted as consistent with theories of hippocampal function that emphasize its role in integrating multiple stimulus elements in a memory trace. © 2007 Wiley-Liss, Inc. [source] Enhancing technology development through integrated environmental analysis: Toward sustainable nonlethal military systemsINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 2 2010Oral S. Saulters Abstract New technologies are not only critical in supporting traditional industrial and military success but also play a pivotal role in advancing sustainability and sustainable development. With the current global economic challenges, resulting in tighter budgets and increased uncertainty, synergistic paradigms and tools that streamline the design and dissemination of key technologies are more important than ever. Accordingly, a proactive and holistic approach can facilitate efficient research, design, testing, evaluation, and fielding for novel and off-the-shelf products, thereby assisting developers, end users, and other diverse stakeholders in better understanding tradeoffs in the defense industry and beyond. By prioritizing mechanisms such as strategic life-cycle environmental assessments (LCEA); programmatic environment, safety, and occupational health evaluations (PESHE); health hazard assessments (HHA); and other innovative platforms and studies early within systems engineering, various nonlethal military technologies have been successfully developed and deployed. These efforts provide a framework for addressing complex environment, safety, and occupational health risks that affect personnel, infrastructure, property, socioeconomic, and natural/cultural resources. Moreover, integrated, comprehensive, multidisciplinary, and iterative analyses involving flexible groups of specialists/subject matter experts can be applied at various spatiotemporal scales in support of collaborations. This paper highlights the Urban Operations Laboratory process utilized for inclusive and transformative environmental analysis, which can translate into advantages and progress toward sustainable systems. Integr Environ Assess Manag 2010;6:281,286. © 2009 SETAC [source] Alternatives to pilot plant experiments in cheese-ripening studiesINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 4 2001Shakeel-ur-rehman Experimental studies on cheese have several objectives, from assessing the influence of the microflora and enzymes indigenous to milk to evaluating starters and adjuncts. Several studies have been undertaken to evaluate the influence of an individual ripening agent in the complex environment of cheese. Cheesemaking experiments, even on a pilot scale, are expensive and time-consuming, and when controlled bacteriological conditions are needed, pilot plant experiments are difficult to perform. Cheese curd slurries are simple models that can be prepared under sterile conditions in the laboratory and can be used as an intermediate between test tubes and cheese trials, but probably cannot replace the latter. Miniature model cheeses are similar to pilot plant cheeses and can be manufactured under sterile conditions. Several approaches to assess the role of cheese-ripening agents are reviewed in this paper. [source] Tracking a partially occluded target with a cluster of Kalman filtersINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 6 2002Dae-Sik Jang Tracking moving objects is one of the most important techniques in motion analysis and understanding, and it has many difficult problems to solve. Estimating and identifying moving objects, when the background and moving objects vary dynamically, are especially difficult. It is possible under such a complex environment that targets might disappear totally or partially due to occlusion by other objects. The Kalman filter has been used to estimate motion information and use the information in predicting the appearance of targets in succeeding frames. In this article, we propose another version of the Kalman filter, to be called the structural Kalman filter, which can successfully accomplish its role of estimating motion information under such a deteriorating condition as occlusion. Experimental results show that the suggested approach is very effective in estimating and tracking non-rigid moving objects reliably. © 2002 Wiley Periodicals, Inc. [source] Activation of caspase 3 during shear stress-induced neutrophil apoptosis on biomaterialsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2002Matthew S. Shive Abstract Within the complex environment of an implanted cardiovascular device comprised of dynamic flow and foreign materials, phagocytic neutrophils may be ineffective in combating infection due to cellular responses to shear stress. This may be explained, in part, by our recent reports of apoptosis of biomaterial-adherent leukocytes induced through exposure to shear stress. Here we utilize a rotating disk system to generate physiologically relevant shear stress levels (0,18 dynes/cm2) at the surface of a polyetherurethane urea (PEUU) and investigate neutrophil intracellular pathways involved in shear-induced apoptosis. In situ detection of activated caspases, the enzymatic mediators of the apoptosis cascade, showed qualitatively that these proteases participate in shear-induced apoptosis and are activated in a shear-dependent manner. The involvement of caspase 3 was confirmed through immunoprecipitation and immunoblotting of extracted neutrophil proteins. Comparative studies with neutrophils adherent under static conditions demonstrated time-dependent activation of caspases in TNF-,/cycloheximide-induced apoptosis, for which caspase-3 also was implicated. These findings are the first steps toward elucidation of the mechanisms behind the inappropriate induction of apoptosis by adhesion to biomaterials, which may contribute to the development and persistence of device-related infections. ©2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 163,168, 2002 [source] Ammonia in estuaries and effects on fishJOURNAL OF FISH BIOLOGY, Issue 6 2005F. B. Eddy This review aims to explore the biological responses of fish in estuaries to increased levels of environmental ammonia. Results from laboratory and field studies on responses of fish to varying salinity and their responses increased ammonia will be evaluated, although studies which examine responses to ammonia, in relation to varying salinity, pH and temperature together are rare. In a survey of British estuaries the continuous measurement of total ammonia showed values that ranged from background levels increasing up to c. 10 mg N l,1 although higher values have been noted sporadically. In outer estuaries pH values tended to stabilize towards sea water values (e.g. c. pH 8). Upper reaches of estuaries are influenced by the quality of their fresh waters sources which can show a wide range of pH and water quality values depending on geological, climatic and pollution conditions. In general the ammonia toxicity (96 h LC50) to marine species (e.g. 0·09,3·35 mg l,1 NH3) appears to be roughly similar to freshwater species (e.g. 0·068,2·0 mg l,1 NH3). Ammonia toxicity is related to differences between species and pH rather than to the comparatively minor influences of salinity and temperature. In the marine environment the toxicity of ionized ammonia should be considered. The water quality standard for freshwater salmonids of 21 ,g l,1 NH3,N was considered to be protective for most marine fish and estuarine fish although the influence of cyclical changes in pH, salinity and temperature were not considered. During ammonia exposures, whether chronic or episodic, estuarine fish may be most at risk as larvae or juveniles, at elevated temperatures, if salinity is near the seawater value and if the pH value of the water is decreased. They are also likely to be at risk from ammonia intoxication in waters of low salinity, high pH and high ammonia levels. These conditions are likely to promote ammonia transfer from the environment into the fish, both as ionized and unionized ammonia, as well as promoting ammonia retention by the fish. Fish are more likely to be prone to ammonia toxicity if they are not feeding, are stressed and if they are active and swimming. Episodic or cycling exposures should also be considered in relation to the rate at which the animal is able to accumulate and excrete ammonia and the physiological processes involved in the transfer of ammonia. In the complex environment of an estuary, evaluation of ammonia as a pollutant will involve field and laboratory experiments to determine the responses of fish to ammonia as salinity and temperature vary over a period of time. It will also be necessary to evaluate the responses of a variety of species including estuarine residents and migrants. [source] Environmental enrichment and prior experience of live prey improve foraging behaviour in hatchery-reared Atlantic salmonJOURNAL OF FISH BIOLOGY, Issue 2003C. Brown Atlantic salmon salmo salar L. parr were reared for 3 months under standard hatchery conditions or in a structurally enriched tank (containing plants, rocks and novel objects). Half of each of these fish had prior exposure to live prey in the form of live bloodworm while the other half were fed hatchery-pellets. After 12 days all fish were tested on a novel live prey item (brine shrimp). A significant interaction between the two factors (prior exposure to live prey and rearing condition) revealed that foraging performance was only enhanced in fish that had been reared in a complex environment and exposed to live prey. It appears that the ability to generalize from one live prey type to another is only enhanced in fish that had been reared in an enriched environment. The findings support the assertion that the provision of enriched environments in combination with exposure to live prey prior to release may significantly improve the post-release survival rates of hatchery-reared fishes. As both the environmental enrichment and the prior foraging experience procedures were comparatively simple, the provision of such pre-release experiences are likely to prove cost effective to hatcheries. [source] Toward implementing distributed scaffolding: Helping students learn science from designJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 2 2005Sadhana Puntambekar In this article, we present two studies that helped us understand the kinds of support that students need to learn science successfully from design activities. Both were enacted in the context of an approach to learning science from design called learning by design (LBD). In our first study, we designed and integrated a paper-and-pencil scaffolding tool, the design diary, into an LBD unit to support students' design-related activities. We learned two important lessons from the first study. First, we refined our understanding of the processes involved in designing and the ways we might present those processes to students. Second, and more important, we observed that in the dynamic, complex environment of the classroom, not all of the scaffolding could be provided with any one tool or agent. We found that students need multiple forms of support and multiple learning opportunities to learn science successfully from design activities. In our next study, we provided additional support through an organized system of tools and agents. Our analysis of data from the second study leads us to believe that supporting multiple students in a classroom requires us to rethink the notion of scaffolding as it applied to groups of learners in a classroom. We put forth the notion of distributed scaffolding as an approach to supporting hands-on inquiry learning in a classroom. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 185,217, 2005 [source] Principles in quality assurance.QUALITY ASSURANCE JOURNAL, Issue 4 2002Part 1. Abstract The regulated pharmaceutical industry is an ocean of complexity and detail through which Quality Assurance (QA) professionals must steer the best course, playing a crucial role in the profitability of the industry and the well-being of patients. How best to keep the 'good ship' QA stable and effective while being battered by the numerous changing priorities, last-minute demands, or unforeseen events, is a challenge to us all, and the subject of this paper. The ideas presented here are simple, perhaps simplistic, and stem from the idea that, in order to be effective in this complex environment, we have to find some fundamental unifying concepts that can be applied consistently to our work. Semantics aside, we will consider these unifying concepts to be 'principles' and this paper will describe their definition and application within a bioanalytical Contract Research Organization (CRO). Copyright © 2002 John Wiley & Sons, Ltd. [source] Older people's assets: a contested site,AUSTRALASIAN JOURNAL ON AGEING, Issue 2005Cheryl Tilse The management of the financial assets of older people is increasingly important in the current policy context. Competing interests from the state, the market and the family regarding the appropriate use of these assets suggest that non-professional managers are assisting older people in a complex environment. This paper, based on a national prevalence study and an in-depth study, explores the nature and extent of asset management on behalf of older people. It examines the role of legal provision for substitute decision-making in these processes and concludes that the current provision is insufficient to protect older people from financial abuse and support carers to manage assets well. This paper proposes that more broadly based interventions are required in a complex environment of competing interests. Such interventions include attitudinal change, improved financial literacy, information and support for older people and informal asset managers and improved monitoring and support for substitute decision makers. [source] The challenge of interdisciplinary collaboration in acute psychiatry: Impacts on the occupational milieuAUSTRALIAN OCCUPATIONAL THERAPY JOURNAL, Issue 2 2009Tracy Fortune This paper, based on a larger ethnographic exploration of the acute inpatient environment for older people with mental illness, describes and provides interpretations of staff perceptions and actions in order to highlight tensions between professional groups which adversely affect opportunities for patients to engage in meaningful occupations. Fieldwork conducted in 1999,2000, supplemented by 20 in-depth interviews with a range of mental health professionals, provides the foundation for suggesting that the extent and nature of occupational engagement is significantly impacted by interdisciplinary relations. The skill of occupational therapists to collaborate with their nursing colleagues in a socially complex environment, and the importance of personal leadership skills among our new graduates are discussed. [source] Windows to cell function and dysfunction: Signatures written in the boundary layersBIOESSAYS, Issue 6 2010Peter J. S. Smith Abstract The medium surrounding cells either in culture or in tissues contains a chemical mix varying with cell state. As solutes move in and out of the cytoplasmic compartment they set up characteristic signatures in the cellular boundary layers. These layers are complex physical and chemical environments the profiles of which reflect cell physiology and provide conduits for intercellular messaging. Here we review some of the most relevant characteristics of the extracellular/intercellular space. Our initial focus is primarily on cultured cells but we extend our consideration to the far more complex environment of tissues, and discuss how chemical signatures in the boundary layer can or may affect cell function. Critical to the entire essay are the methods used, or being developed, to monitor chemical profiles in the boundary layers. We review recent developments in ultramicro electrochemical sensors and tailored optical reporters suitable for the task in hand. [source] The radiation of the Cape flora, southern AfricaBIOLOGICAL REVIEWS, Issue 4 2003H. P. LINDER ABSTRACT The flora of the south-western tip of southern Africa, the Cape flora, with some 9000 species in an area of 90 000 km2 is much more speciose than can be expected from its area or latitude, and is comparable to that expected from the most diverse equatorial areas. The endemism of almost 70%, on the other hand, is comparable to that found on islands. This high endemism is accounted for by the ecological and geographical isolation of the Cape Floristic Region, but explanations for the high species richness are not so easily found. The high species richness is accentuated when its taxonomic distribution is investigated: almost half of the total species richness of the area is accounted for by 33,Cape floral clades'. These are clades which may have initially diversified in the region, and of which at least half the species are still found in the Cape Floristic Region. Such a high contribution by a very small number of clades is typical of island floras, not of mainland floras. The start of the radiation of these clades has been dated by molecular clock techniques to between 18 million years ago (Mya)(Pelargonium) and 8 Mya (Phylica), but only six radiations have been dated to date. The fossil evidence for the dating of the radiation is shown to be largely speculative. The Cenozoic environmental history of southern Africa is reviewed in search of possible triggers for the radiations, climatic changes emerge as the most likely candidate. Due to a very poor fossil record, the climatic history has to be inferred from larger scale patterns, these suggest large-scale fluctuations between summer wet (Palaeocene, Early Miocene)and summer dry climates (Oligocene, Middle Miocene to present). The massive speciation in the Cape flora might be accounted for by the diverse limitations to gene flow (dissected landscapes, pollinator specialisation, long flowering times allowing much phenological specialisation), as well as a richly complex environment providing a diversity of selective forces (geographically variable climate, much altitude variation, different soil types, rocky terrain providing many micro-niches, and regular fires providing both intermediate disturbances, as well as different ways of surviving the fires). However, much of this is based on correlation, and there is a great need for (a)experimental testing of the proposed speciation mechanisms, (b)more molecular clock estimates of the age and pattern of the radiations, and (c)more fossil evidence bearing on the past climates. [source] Computational study of conformational and chiroptical properties of (2R,3S,4R)-(+)-3,3,,4,4,,7-flavanpentolCHIRALITY, Issue 9 2005Chiara Cappelli Abstract Conformational analysis of (2R,3S,4R)-(+)-3,3,,4,4,,7-flavanpentol, a flavonoid compound displaying both antioxidant and pro-oxidant properties, is performed by molecular mechanics and density functional theory calculations both in the gas phase and in methanol solution by using the Polarizable Continuum Model. Nine different conformations are identified. Absorption (UV) and circular dichroism (CD) spectra and optical rotations are calculated by means of time dependent density functional theory (TDDFT) and compared with experiments. The effects of a complex environment formed by water and proline-rich peptide molecules on the conformational characteristics of (2R,3S,4R)-(+)-3,3,,4,4,,7-flavanpentol and therefore on its UV and CD spectra are investigated by atomistic molecular dynamics simulations. © 2005 Wiley-Liss, Inc. Chirality 17:577,589, 2005. [source] Newborn human brain identifies repeated auditory feature conjunctions of low sequential probabilityEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2004Timo Ruusuvirta Abstract Natural environments are usually composed of multiple sources for sounds. The sounds might physically differ from one another only as feature conjunctions, and several of them might occur repeatedly in the short term. Nevertheless, the detection of rare sounds requires the identification of the repeated ones. Adults have some limited ability to effortlessly identify repeated sounds in such acoustically complex environments, but the developmental onset of this finite ability is unknown. Sleeping newborn infants were presented with a repeated tone carrying six frequent (P = 0.15 each) and six rare (P ,0.017 each) conjunctions of its frequency, intensity and duration. Event-related potentials recorded from the infants' scalp were found to shift in amplitude towards positive polarity selectively in response to rare conjunctions. This finding suggests that humans are relatively hard-wired to preattentively identify repeated auditory feature conjunctions even when such conjunctions occur rarely among other similar ones. [source] Cooperative forms of governance: Problems of democratic accountability in complex environmentsEUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 4 2003YANNIS PAPADOPOULOS Various schools of research in public policy (the literature on ,governance' and its continental counterparts) are converging to focus on the growth of policy styles based on cooperation and partnership in networks, instead of on vertical control by the state. This article focuses on issues of democratic accountability and responsiveness with these governance arrangements. It argues that until recently the legitimacy of governance networks was not at the forefront of theoretical developments, even though the ,democratic deficit' of governance is problematic both for normative and for pragmatic reasons. There is now increased sensitivity to this problem, but the remedies presented in the literature are unsatisfactory, and critiques of governance presuppose a somewhat idealised image of representative democracy in terms of accountability or responsiveness of decision-makers. They also fail to offer adequate solutions to some of the central legitimacy problems of policy-making in complex societies. [source] Progress towards understanding the fate of plasmids in bacterial communitiesFEMS MICROBIOLOGY ECOLOGY, Issue 1 2008Frances R. Slater Abstract Plasmid-mediated horizontal gene transfer influences bacterial community structure and evolution. However, an understanding of the forces which dictate the fate of plasmids in bacterial populations remains elusive. This is in part due to the enormous diversity of plasmids, in terms of size, structure, transmission, evolutionary history and accessory phenotypes, coupled with the lack of a standard theoretical framework within which to investigate them. This review discusses how ecological factors, such as spatial structure and temporal fluctuations, shape both the population dynamics and the physical features of plasmids. Novel data indicate that larger plasmids are more likely to be harboured by hosts in complex environments. Plasmid size may therefore be determined by environmentally mediated fitness trade-offs. As the correlation between replicon size and complexity of environment is similar for plasmids and chromosomes, plasmids could be used as tractable tools to investigate the influence of ecological factors on chromosomes. Parallels are drawn between plasmids and bacterial facultative symbionts, including the evolution of some members of both groups to a more obligate relationship with their host. The similarity between the influences of ecological factors on plasmids and bacterial symbionts suggests that it may be appropriate to study plasmids within a classical ecological framework. [source] The relationship between busyness and research utilization: it is about timeJOURNAL OF CLINICAL NURSING, Issue 4 2008David S Thompson MN Aims and objectives., To explore the concept of busyness in nursing and to understand the relationship between busyness and nurses' research utilization better. Background., Lack of time and busyness are consistently reported as barriers to research utilization. Current literature fails to identify the dimensions of busyness and offers little insight into the relationship between busyness and nurses' research utilization. Design/Methods., We performed a secondary analysis of qualitative data and created a conceptual map of busyness in nursing. Results., Our results suggested that busyness consists of physical and psychological dimensions. Interpersonal and environmental factors influenced both dimensions. Cultural and intrapersonal factors contributed to psychological elements. The effects of busyness reported included missed opportunities, compromised safety, emotional and physical strain, sacrifice of personal time, incomplete nursing care and the inability to find or use resources. Conclusions., Our beginning description of busyness contributes to a greater understanding of the relationship between busyness and research utilization. Our findings suggest that lack of time as a barrier to research utilization is more complex than depicted in the literature. Instead, the mental time and energy required to navigate complex environments and a culture of busyness more accurately reflect what may be meant by ,lack of time' as a barrier to research utilization. Relevance to clinical practice., Future interventions aimed at increasing research utilization may be more effective if they focus on factors that contribute to a culture of busyness in nursing and address the mental time and energy required for nurses to use research in practice. [source] Computational screening of biomolecular adsorption and self-assembly on nanoscale surfacesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 7 2010Hendrik Heinz Abstract The quantification of binding properties of ions, surfactants, biopolymers, and other macromolecules to nanometer-scale surfaces is often difficult experimentally and a recurring challenge in molecular simulation. A simple and computationally efficient method is introduced to compute quantitatively the energy of adsorption of solute molecules on a given surface. Highly accurate summation of Coulomb energies as well as precise control of temperature and pressure is required to extract the small energy differences in complex environments characterized by a large total energy. The method involves the simulation of four systems, the surface-solute,solvent system, the solute,solvent system, the solvent system, and the surface-solvent system under consideration of equal molecular volumes of each component under NVT conditions using standard molecular dynamics or Monte Carlo algorithms. Particularly in chemically detailed systems including thousands of explicit solvent molecules and specific concentrations of ions and organic solutes, the method takes into account the effect of complex nonbond interactions and rotational isomeric states on the adsorption behavior on surfaces. As a numerical example, the adsorption of a dodecapeptide on the Au {111} and mica {001} surfaces is described in aqueous solution. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] State space sampling of feasible motions for high-performance mobile robot navigation in complex environmentsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 6-7 2008Thomas M. Howard Sampling in the space of controls or actions is a well-established method for ensuring feasible local motion plans. However, as mobile robots advance in performance and competence in complex environments, this classical motion-planning technique ceases to be effective. When environmental constraints severely limit the space of acceptable motions or when global motion planning expresses strong preferences, a state space sampling strategy is more effective. Although this has been evident for some time, the practical question is how to achieve it while also satisfying the severe constraints of vehicle dynamic feasibility. The paper presents an effective algorithm for state space sampling utilizing a model-based trajectory generation approach. This method enables high-speed navigation in highly constrained and/or partially known environments such as trails, roadways, and dense off-road obstacle fields. © 2008 Wiley Periodicals, Inc. [source] A New Navigation Method for an Automatic Guided VehicleJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 3 2004Chen Wuwei This paper presents a new navigation method for an automatic guided vehicle (AGV). This method utilizes a new navigation and control scheme based on searching points on an arc. Safety measure indices are defined and are generated from the output of a fuzzy neural network which define the actions the AGV is to take when in the presence of obstacles. The proposed algorithm integrates several functions required for automatic guided vehicle navigation and tracking control and it exhibits satisfactory performance when maneuvering in complex environments. The automatic guided vehicle with this navigation control system not only can quickly process environmental information, but also can efficiently avoid dynamic or static obstacles, and reach targets safely and reliably. Extensive simulation and experimental results demonstrate the effectiveness and correct behavior of this scheme. © 2004 Wiley Periodicals, Inc. [source] Quantifying habitat structure: surface convolution and living space for species in complex environmentsOIKOS, Issue 12 2008D. M. Warfe Habitat complexity is often used to explain the distribution of species in environments, yet the ability to predict outcomes of structural differences between habitats remains elusive. This stems from the difficulty and lack of consistency in measuring and quantifying habitat structure, making comparison between different habitats and systems problematic. For any measure of habitat structure to be useful it needs to be applicable to a range of habitats and have relevance to their associated fauna. We measured three differently-shaped macrophyte analogues with nine indices of habitat structure to determine which would best distinguish between their shape and relate to the abundance and rarefied species richness of their associated macroinvertebrate assemblages. These indices included the physical, whole-plant attributes of surface area (SA) and plant volume (PV), the interstitial space attributes of average space size and frequency (ISI), average refuge space from predation (Sp/Pr), and total refuge space (FFV), and the degree of surface convolution at a range of scales (i.e. the fractal dimension at four spatial scales: 7.5×, 5×, 2.5× and 1× magnification). We found a high degree of inter-correlation between the structural indices such that they could be organised into two suites: one group describing interstitial space and surface convolution at coarse scales, the other describing whole-plant attributes and surface convolution at fine scales. Two of these indices fell into both suites: the average refuge space from predation (Sp/Pr) and the fractal dimension at 5× magnification. These two measures were also strongly related to macroinvertebrate abundance and rarefied species richness, which points to their usefulness in quantifying habitat structure and illustrates that habitat structure depends not just on shape, but on the space associated with shape. [source] On the elastic contribution to crystal growth in complex environmentsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2005A. Gadomski Abstract Based on a number of experimental studies, we propose to consider how elastic interactions between a crystal and its surroundings change crystal growing conditions. To aim to do this, we analyze the influence of some nonequilibrium modification of the Gibbs,Thomson thermodynamic condition, prescribed at the crystal boundary, on some properties of a kinetic model of protein crystal growth in a mass-convection regime. Next, to draw the physical picture more realistically, we study the influence of a certain stochastic perturbation on the crystal growth rate. To fulfill the task we apply the description of crystal growth in terms of nonequilibrium thermodynamics at a mesoscopic level. The proposed model offers a quite comprehensive picture of the formation of modern organic crystalline materials such as non-Kossel crystals. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Advanced tilt correction from flow distortion effects on turbulent CO2 fluxes in complex environments using large eddy simulationTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 643 2009F. Griessbaum Abstract Measurement of the turbulent fluxes of gases, momentum and heat can be biased by obstacles such as buildings or instrument platforms distorting the flow of air to the flux instruments. Standard methods have long been used to account for non-horizontal mean flows. Here we demonstrate a novel approach to correct for the effects of flow distortion which combines numerical flow modelling with eddy covariance measurements of the fluxes. This approach applies a flow distortion correction to the data prior to the application of the standard planar-fit and double-rotation methods. This new direction-dependent flow correction allows the determination of the correct orthogonal wind vector components and hence the vertical turbulent fluxes. We applied the method to a 10 Hz dataset of 3D wind components, temperature, and the concentrations of carbon dioxide and water vapour, as measured on top of a military tower above the city of Münster in northwest Germany during spring and summer 2007. Significant differences appeared between the fluxes that were calculated with the standard rotation methods alone and those that underwent flow distortion correction prior to the application of the rotation methods. The highest deviations of 27% were obtained for the momentum flux. Pronounced differences of 15% and 8% were found for the diurnal net fluxes of carbon dioxide and water vapour, respectively. The flow distortion correction for the carbon dioxide fluxes yielded the same magnitude as the WPL (Webb,Pearman,Leuning) correction for density fluctuations. Copyright © 2009 Royal Meteorological Society [source] | |||||||||||||||||||||||||||||||