Inherent Limitations (inherent + limitation)

Distribution by Scientific Domains


Selected Abstracts


Inherent limitations and control design for camless engine idle speed dynamics

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 11 2001
Yan Wang
Abstract The idle speed control problem of a spark-ignited engine equipped with a camless valvetrain is considered. The camless valvetrain allows control of the individual intake and exhaust valves of each cylinder and can be used to achieve unthrottled operation, and consequently, optimize the engine performance. We formulate the speed control problem for this engine and show that it exhibits unstable open-loop behaviour with a significant delay in the feedback loop. The instability is intrinsic to the unthrottled operation and specific to the camless actuation used to achieve the unthrottled operation. The delay is caused by the discrete combustion process and the sensor/computer/actuator interface. We demonstrate the inherent system limitations associated with the unstable dynamics and the delay and provide insight on the structural (plant) design that can alleviate these limitations. Finally, stabilizing controllers using classical and modern robust design techniques are presented and tested on a nonlinear simulation model. Copyright © 2001 John Wiley & Sons, Ltd. [source]


Single-molecule analysis of chromatin: Changing the view of genomes one molecule at a time

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2008
Santhi Pondugula
Abstract Wrapping DNA into chromatin provides a wealth of regulatory mechanisms that ensure normal growth and development in eukaryotes. Our understanding of chromatin structure, including nucleosomes and non-histone protein,DNA interactions, has benefited immensely from nuclease and chemical digestion techniques. DNA-bound proteins, such as histones or site-specific factors, protect DNA against nuclease cleavage and generate large nucleosomal or small regulatory factor footprints. Chromatin subject to distinct modes of regulation often coincides with sites of nuclease hypersensitivity or nucleosome positioning. An inherent limitation of cleavage-based analyses has been the inability to reliably analyze regions of interest when levels of digestion depart from single-hit kinetics. Moreover, cleavage-based techniques provide views that are averaged over all the molecules in a sample population. Therefore, in cases of occupancy of multiple regulatory elements by factors, one cannot define whether the factors are bound to the same or different molecules in the population. The recent development of DNA methyltransferase-based, single-molecule MAP-IT technology overcomes limitations of ensemble approaches and has opened numerous new avenues in chromatin research. Here, we review the strengths, limitations, applications and future prospects of MAP-IT ranging from structural issues to mechanistic questions in eukaryotic chromatin regulation. J. Cell. Biochem. 105: 330,337, 2008. © 2008 Wiley-Liss, Inc. [source]


The development of risk criteria for high severity low frequency events,

PROCESS SAFETY PROGRESS, Issue 1 2009
Fred Henselwood
Abstract Quantitative risk assessments (QRAs) are used within the field of process safety to decide the allocation of resources and risk reduction investments. Typically risk assessments involve the evaluation of probabilistic measures that estimate the average expected value for the situation being considered across a range of potential outcomes. The resulting expected value is then used to determine if a situation represents an acceptable or unacceptable risk based on a threshold value allotted to the risk. This approach often gives guidance that is at odds with the thoughts and behaviors of some stakeholders as illustrated by the "but what if it does happen?" type of question. This inconsistency results from the inherent limitation associated with expected value approaches in that the methodology is based on whether or not a mean assessed risk represents an acceptable risk while overlooking the possibility that a single scenario could represent an intolerable event. This article looks at an adjustment to traditional QRAs so as to assess both the acceptability of risk and the tolerability of the associated consequences relative to risk criteria. These adjustments have been found to better represent stakeholder perceptions of risk, more closely relate risk tolerance to corporate values and resources, and to better justify the use of various risk transfer strategies. © 2008 American Institute of Chemical Engineers Process Saf Prog, 2009 [source]


3D In-Vivo Optical Skin Imaging for Topographical Quantitative Assessment of Non-Ablative Laser Technology

DERMATOLOGIC SURGERY, Issue 3 2002
Paul M. Friedman MD
background. A new method for treating facial rhytides and acne scars with nonablative laser and light source techniques has recently been introduced. Given the inherent limitations of photographic and clinical evaluation to assess subtle changes in rhytides and surface topography, a new noninvasive objective assessment is required to accurately assess the outcomes of these procedures. objective. The purpose of this study was to measure and objectively quantify facial skin using a novel, noninvasive, In-vivo method for assessing three-dimensional topography. This device was used to quantify the efficacy of five treatment sessions with the 1064 nm QS Nd:YAG laser for rhytides and acne scarring, for up to six months following laser treatment. methods. Two subjects undergoing facial rejuvenation procedures were analyzed before and after therapy using a 30-mm, three-dimensional microtopography imaging system (PRIMOS, GFM, Teltow, Germany). The imaging system projects light on to a specific surface of the skin using a Digital Micromirror Device (DMDÔ Texas Instruments, Irving, TX) and records the image with a CCD camera. Skin Surface microtopography is reconstructed using temporal phase shift algorithms to generate three-dimensional images. Measurements were taken at baseline, at various times during the treatment protocol, and then at three and six-month follow-up visits. Silicone skin replicas (FLEXICO, Herts, England) were also made before and after the laser treatment protocol for comparison to In-vivo acquisition. results. Skin roughness decreased by 11% from baseline after three treatment sessions in the wrinkles subject, while a 26% improvement of skin roughness was recorded by 3D In-vivo assessment six months following the fifth treatment session. The subject with acne scarring demonstrated a 33% decrease in roughness analysis after three treatment sessions by 3D In-vivo assessment. A 61% improvement in surface topography was recorded 3-months following the fifth treatment session, which was maintained at the 6-month follow-up. conclusion. Three-dimensional In-vivo optical skin imaging provided a rapid and quantitative assessment of surface topography and facial fine lines following multiple treatment sessions with a 1064-nm QS Nd:YAG laser, correlating with clinical and subjective responses. This imaging technique provided objective verification and technical understanding of nonablative laser technology. Wrinkle depth and skin roughness decreased at the three and six-month follow-up evaluations by 3D In-vivo assessment, indicating ongoing dermal collagen remodeling after the laser treatment protocol. Future applications may include comparison of nonablative laser technology, optimization of treatment regimens, and objective evaluation of other aesthetic procedures performed by dermatologists. [source]


Animal models of rheumatoid arthritis

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2009
Darren L. Asquith
Abstract Animal models have been used extensively in studies of rheumatoid arthritis pathogenesis. Despite the inherent limitations of all animal models, several rodent models have significantly progressed our understanding of the fundamental mechanisms underpinning rheumatoid arthritis and contributed to several current major advances in treatment. These models include the induced arthritis models such as collagen-induced arthritis, collagen-antibody-induced arthritis, zymosan-induced arthritis, and the methylated BSA model, and the genetically manipulated or spontaneous arthritis models such as the TNF-,-transgenic mouse, K/BxN mouse, and the Skg mouse. Here, we describe these animal models and discuss their advantages and limitations. [source]


Molecular investigations into a globally important carbon pool: permafrost-protected carbon in Alaskan soils

GLOBAL CHANGE BIOLOGY, Issue 9 2010
M. P. WALDROP
Abstract The fate of carbon (C) contained within permafrost in boreal forest environments is an important consideration for the current and future carbon cycle as soils warm in northern latitudes. Currently, little is known about the microbiology or chemistry of permafrost soils that may affect its decomposition once soils thaw. We tested the hypothesis that low microbial abundances and activities in permafrost soils limit decomposition rates compared with active layer soils. We examined active layer and permafrost soils near Fairbanks, AK, the Yukon River, and the Arctic Circle. Soils were incubated in the lab under aerobic and anaerobic conditions. Gas fluxes at ,5 and 5 °C were measured to calculate temperature response quotients (Q10). The Q10 was lower in permafrost soils (average 2.7) compared with active layer soils (average 7.5). Soil nutrients, leachable dissolved organic C (DOC) quality and quantity, and nuclear magnetic resonance spectroscopy of the soils revealed that the organic matter within permafrost soils is as labile, or even more so, than surface soils. Microbial abundances (fungi, bacteria, and subgroups: methanogens and Basidiomycetes) and exoenzyme activities involved in decomposition were lower in permafrost soils compared with active layer soils, which, together with the chemical data, supports the reduced Q10 values. CH4 fluxes were correlated with methanogen abundance and the highest CH4 production came from active layer soils. These results suggest that permafrost soils have high inherent decomposability, but low microbial abundances and activities reduce the temperature sensitivity of C fluxes. Despite these inherent limitations, however, respiration per unit soil C was higher in permafrost soils compared with active layer soils, suggesting that decomposition and heterotrophic respiration may contribute to a positive feedback to warming of this eco region. [source]


Superior virological response to boosted protease inhibitor-based highly active antiretroviral therapy in an observational treatment programme

HIV MEDICINE, Issue 2 2007
E Wood
Background The use of boosted protease inhibitor (PI)-based antiretroviral therapy has become increasingly recommended in international HIV treatment consensus guidelines based on the results of randomized clinical trials. However, the impact of this new treatment strategy has not yet been evaluated in community-treated cohorts. Methods We evaluated baseline characteristics and plasma HIV RNA responses to unboosted and boosted PI-based highly active antiretroviral therapy (HAART) among antiretroviral-naïve HIV-infected patients in British Columbia, Canada who initiated HAART between August 1997 and September 2003 and who were followed until September 2004. We evaluated time to HIV-1 RNA suppression (<500 HIV-1 RNA copies/mL) and HIV-1 RNA rebound (,500 copies/mL), while stratifying patients into those that received boosted and unboosted PI-based HAART as the initial regimen, using Kaplan,Meier methods and Cox proportional hazards regression. Results During the study period, 682 patients initiated therapy with unboosted PI and 320 individuals initiated HAART with a boosted PI. Those who initiated therapy with a boosted PI were more likely to have a CD4 cell count <200 cells/,L and to have a plasma HIV RNA>100 000 copies/mL, and to have AIDS at baseline (all P<0.001). However, when we examined virological response rates, those who initiated HAART with a boosted PI achieved more rapid virological suppression [relative hazard 1.26, 95% confidence interval (CI) 1.06,1.51, P=0.010]. Conclusions Patients prescribed boosted PIs achieved superior virological response rates despite baseline factors that have been associated with inferior virological responses to HAART. Despite the inherent limitations of observational studies which require this study be interpreted with caution, these findings support the use of boosted PIs for initial HAART therapy. [source]


Emotional Intelligence: Toward Clarification of a Concept

INDUSTRIAL AND ORGANIZATIONAL PSYCHOLOGY, Issue 2 2010
CARY CHERNISS
There has been much confusion and controversy concerning the concept of emotional intelligence (EI). Three issues have been particularly bothersome. The first concerns the many conflicting definitions and models of EI. To address this issue, I propose that we distinguish between definitions and models and then adopt a single definition on which the major theorists already seem to agree. I further propose that we more clearly distinguish between EI and the related concept of emotional and social competence (ESC). The second issue that has generated concern is the question of how valid existing measures are. After reviewing the research on the psychometric properties of several popular tests, I conclude that although there is some support for many of them, they all have inherent limitations. We need to rely more on alternative measurement strategies that have been available for some time and also develop new measures that are more sensitive to context. The third area of contention concerns the significance of EI for outcomes such as job performance or leadership effectiveness. Recent research, not available to earlier critics, suggests that EI is positively associated with performance. However, certain ESCs are likely to be stronger predictors of performance than EI in many situations. Also, EI is likely to be more important in certain kinds of situations, such as those involving social interaction or significant levels of stress. Context makes a difference. [source]


Biopolitical Management, Economic Calculation and "Trafficked Women"

INTERNATIONAL MIGRATION, Issue 4 2010
Jacqueline Berman PhD
Narratives surrounding human trafficking, especially trafficking in women for sex work, employ gendered and racialized tropes that have among their effects, a shrouding of women's economic decision-making and state collusion in benefiting from their labour. This paper explores the operation of these narratives in order to understand the ways in which they mask the economics of trafficking by sensationalizing the sexual and criminal aspects of it, which in turn allows the state to pursue political projects under the guise of a benevolent concern for trafficked women and/or protection of its own citizens. This paper will explore one national example: Article 18 of Italian Law 40 (1998). I argue that its passage has led to an increase in cooperation with criminal prosecution of traffickers largely because it approaches trafficked women as capable of making decisions about how and what they themselves want to do. This paper will also consider a more global approach to trafficking embedded in the concept of "migration management", an International Organization for Migration (IOM) framework that is now shaping EU, US and other national immigration laws and policies that impact trafficking. It will also examine the inherent limitations of both the national and global approach as an occasion to unpack how Article 18 and Migration Management function as forms of biopolitical management that participate in the production of "trafficking victims" into a massified population to be managed, rather than engender a more engaged discussion of what constitutes trafficking and how to redress it. [source]


Foundational Value of Statistics Education for Management Curriculum

INTERNATIONAL STATISTICAL REVIEW, Issue 3 2007
Hirokuni Tamura
Traitement humain de l'information; Education/Enseignement; Prise de décision; Prévision; Modèles statistiques Summary The purpose of this paper is to propose a unique and distinct value of statistics education for management. The 1986 inaugural conference on Making Statistics More Effective in Schools of Business (MSMESB) proposed valuable guidelines for reforming statistics education in schools of business. However, a survey conducted by McAlevey & Everett (2001) identified that their impact has been minimal, and argued that structural problems many business schools have are the potential cause. We argue these structural problems exist because the value of the body of statistical tools for management is ambiguous and has not been made explicit. The unique and distinct value of statistics for management can be identified as the body of tools necessary to meet the inherent needs of a manager charged with making predictive judgments facing data. The need arises because human information-processing capacity is quite limited, as the findings of researchers in cognitive psychology testify. These findings also affirm that the basic statistical concepts needed for processing data cannot be learned from management experiences. The model of a manager faced with data, while considering the evidence of inherent limitations of human information-processing capacity, establishes the foundational value of statistics training in the management curriculum. Statistics education in business schools will be made more effective when management educators recognize such value of the discipline, lend their support and reward the ownership commitment for continuous improvement and innovations of the business statistics curriculum. Résumé Le but de cet article est de proposer une valeur unique et particulière de l'enseignement des statistiques dans le domaine de la gestion. La conférence inaugurale de 1986 traitant des moyens d'améliorer l'efficacité de cet enseignement dans les écoles de gestion a proposé des lignes directrices valables pour la réforme de l'enseignement des statistiques dans les écoles de gestion. Néanmoins, un sondage effectué par McAlevey & Everett (2001), a identifié leur impact comme étant minimal et en attribue la cause probable aux problèmes structurels des écoles de gestion. Nous considérons que ces problèmes existent parce que la valeur du corpus statistique de gestion est ambigüe et n'a pas été mise en lumière. La valeur unique et distincte des statistiques de gestion peut être identifiée comme un corpus d'outils nécessaires pour répondre aux besoins inhérents d'un gestionnaire chargé de faire des prévisions au moyen d'informations brutes. Ce besoin vient du fait que la capacité humaine de traitement de l'information est limitée ainsi qu'en témoignent les recherches en psychologie cognitive. Ces résultats affirment également que les concepts statistiques basiques nécessaires pour le traitement de l'information ne peuvent être acquis par l'expérience de la gestion. Le modèle du gestionnaire confronté de l'information, une fois l'évidence des limites des capacités humaines en matière de traitement de l'information est prise en compte, établi la valeur fondatrice de l'entrainement aux statistiques dans un curriculum de gestion. L'enseignement des statistiques dans les écoles de commerce sera plus efficace quand les responsables de l'éducation reconnaitront cette valeur de la discipline, y apporteront leur soutien et récompenseront les actions visant à l'amélioration et l'innovation constante au sein du curriculum statistique de gestion. [source]


Origin of cardiac progenitor cells in the developing and postnatal heart

JOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2010
Elizabeth N. Kuhn
The mammalian heart lacks the capacity to replace the large numbers of cardiomyocytes lost due to cardiac injury. Several different cell-based routes to myocardial regeneration have been explored, including transplantation of cardiac progenitors and cardiomyocytes into injured myocardium. As seen with cell-based therapies in other solid organ systems, inherent limitations, such as host immune response, cell death and long-term graft instability have hampered meaningful cardiac regeneration. An understanding of the cell biology of cardiac progenitors, including their developmental origin, lineage markers, renewal pathways, differentiation triggers, microenvironmental niche, and mechanisms of homing and migration to the site of injury, will enable further refinement of therapeutic strategies to enhance clinically meaningful cardiac repair. J. Cell. Physiol. 225: 321,325, 2010. © 2010 Wiley-Liss, Inc. [source]


Effects of the past and the present on species distribution: land-use history and demography of wintergreen

JOURNAL OF ECOLOGY, Issue 2 2000
Kathleen Donohue
Summary 1,Past land use can have long-term effects on plant species' distributional patterns if alterations in resources and environmental conditions have persistent effects on population demography (environmental change) and/or if plants are intrinsically limited in their colonization ability (historical factors). 2,We evaluated the role of environmental alteration vs. historical factors in controlling distributional patterns of Gaultheria procumbens, a woody, clonal understorey species with a pronounced restriction to areas that have never been ploughed, and near absence from adjoining areas that were ploughed in the 19th century. The demographic study was conducted in scrub oak and hardwood plant communities on an extensive sand plain, where it was possible to control for the effect of variation in environment prior to land use. 3,The observed demographic effects were contrary to the hypothesis that persistent environmental alteration depressed demographic performance and limited the distribution of G. procumbens. We observed no overall effect of land-use history on stem density, stem recruitment or flower production. In fact, some aspects of performance were enhanced in previously ploughed areas. Populations in previously ploughed areas exhibited less stem mortality in scrub oak transitions, an increase in germination, seedling longevity and proportion of potentially reproductive stems in both plant communities, a trend for slower observed rates of population decline in both plant communities, and a higher projected rate of population growth in the scrub oak transitions. Thus, particularly in scrub oak communities, the lower abundance of G. procumbens in formerly ploughed than in unploughed areas contrasted with its performance. 4,The limited occurrence of G. procumbens in formerly farmed areas was explained instead by its slow intrinsic growth rate, coupled with limited seedling establishment. Lateral population extension occurred exclusively through vegetative growth, allowing a maximum expansion of 43 cm year,1. 5,We conclude that inherent limitations in the colonizing ability of some plant species may present a major obstacle in the restoration or recovery of plant communities on intensively disturbed sites, even in the absence of persistent environmental effects that depress population growth. [source]


Fault-tolerant control of process systems using communication networks

AICHE JOURNAL, Issue 6 2005
Nael H. El-Farra
Abstract A methodology for the design of fault-tolerant control systems for chemical plants with distributed interconnected processing units is presented. Bringing together tools from Lyapunov-based nonlinear control and hybrid systems theory, the approach is based on a hierarchical architecture that integrates lower-level feedback control of the individual units with upper-level logic-based supervisory control over communication networks. The local control system for each unit consists of a family of control configurations for each of which a stabilizing feedback controller is designed and the stability region is explicitly characterized. The actuators and sensors of each configuration are connected, via a local communication network, to a local supervisor that orchestrates switching between the constituent configurations, on the basis of the stability regions, in the event of failures. The local supervisors communicate, through a plant-wide communication network, with a plant supervisor responsible for monitoring the different units and coordinating their responses in a way that minimizes the propagation of failure effects. The communication logic is designed to ensure efficient transmission of information between units, while also respecting the inherent limitations in network resources by minimizing unnecessary network usage and accounting explicitly for the effects of possible delays due to fault-detection, control computations, network communication and actuator activation. The proposed approach provides explicit guidelines for managing the various interplays between the coupled tasks of feedback control, fault-tolerance and communication. The efficacy of the proposed approach is demonstrated through chemical process examples. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source]


Limitations of amorphous content quantification by isothermal calorimetry using saturated salt solutions to control relative humidity: Alternative methods

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2010
Nawel Khalef
Abstract Despite the high sensitivity of isothermal calorimetry (IC), reported measurements of amorphous content by this technique show significant variability even for the same compound. An investigation into the reasons behind such variability is presented using amorphous lactose and salbutamol sulfate as model compounds. An analysis was carried out on the heat evolved as a result of the exchange of water vapor between the solid sample during crystallization and the saline solution reservoir. The use of saturated salt solutions as means of control of the vapor pressure of water within sealed ampoules bears inherent limitations that lead in turn to the variability associated with the IC technique. We present an alternative IC method, based on an open cell configuration that effectively addresses the limitations encountered with the sealed ampoule system. The proposed approach yields an integral whose value is proportional to the amorphous content in the sample, thus enabling reliable and consistent quantifications. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2080,2089, 2010 [source]


Mobile information retrieval with search results clustering: Prototypes and evaluations

JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 5 2009
Claudio Carpineto
Web searches from mobile devices such as PDAs and cell phones are becoming increasingly popular. However, the traditional list-based search interface paradigm does not scale well to mobile devices due to their inherent limitations. In this article, we investigate the application of search results clustering, used with some success for desktop computer searches, to the mobile scenario. Building on CREDO (Conceptual Reorganization of Documents), a Web clustering engine based on concept lattices, we present its mobile versions Credino and SmartCREDO, for PDAs and cell phones, respectively. Next, we evaluate the retrieval performance of the three prototype systems. We measure the effectiveness of their clustered results compared to a ranked list of results on a subtopic retrieval task, by means of the device-independent notion of subtopic reach time together with a reusable test collection built from Wikipedia ambiguous entries. Then, we make a cross-comparison of methods (i.e., clustering and ranked list) and devices (i.e., desktop, PDA, and cell phone), using an interactive information-finding task performed by external participants. The main finding is that clustering engines are a viable complementary approach to plain search engines both for desktop and mobile searches especially, but not only, for multitopic informational queries. [source]


The promise and challenges of bioengineered recombinant clotting factors

JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2005
S. W. PIPE
Summary., The past 10 years of clinical experience have demonstrated the safety and efficacy of recombinant clotting factors. With the adoption of prophylactic strategies, there has been considerable progress in avoiding the complications of hemophilia. Now, insights from our understanding of clotting factor structure and function, mechanisms of hemophilia and inhibitors, gene therapy advances and a worldwide demand for clotting factor concentrates leave us on the brink of embracing targeted bioengineering strategies to further improve hemophilia therapeutics. The ability to bioengineer recombinant clotting factors with improved function holds promise to overcome some of the limitations in current treatment, the high costs of therapy and increase availability to a broader world hemophilia population. Most research has been directed at overcoming the inherent limitations of rFVIII expression and the inhibitor response. This includes techniques to improve rFVIII biosynthesis and secretion, functional activity, half-life and antigenicity/immunogenicity. Some of these proteins have already reached commercialization and have been utilized in gene therapy strategies, while others are being evaluated in pre-clinical studies. These novel proteins partnered with advances in gene transfer vector design and delivery may ultimately achieve persistent expression of FVIII leading to an effective long-term treatment strategy for hemophilia A. In addition, these novel FVIII proteins could be partnered with new advances in alternative recombinant protein production in transgenic animals yielding an affordable, more abundant supply of rFVIII. Novel rFIX proteins are being considered for gene therapy strategies whereas novel rVIIa proteins are being evaluated to improve the potency and extend their plasma half-life. This review will summarize the status of current recombinant clotting factors and the development and challenges of recombinant clotting factors bioengineered for improved function. [source]


New attempts to quantify concentric needle electromyography

MUSCLE AND NERVE, Issue S11 2002
Masahiro Sonoo MD, PhDArticle first published online: 4 JUN 200
Abstract Quantitative motor unit potential (MUP) analysis, which is a leading method of quantitative evaluation of concentric needle electromyography, has several inherent limitations. First, the most essential features of neurogenic or myogenic changes manifest as recruitment abnormalities, rather than as changes in MUP morphology. Second, two factors related to MUP sampling, focusing and level of contraction, greatly influence the parameters of sampled MUPs. Third, the MUP duration, considered to be the cardinal parameter in MUP analysis, has several drawbacks, including low stability and low discriminant sensitivity. We developed a new MUP parameter, the size index (SI), which is calculated from the MUP amplitude and area/amplitude ratio (thickness). The SI remained almost constant during electrode movements, as demonstrated by manual scanning of MUPs. It is a stable and robust parameter and achieved an extremely high ability to discriminate between normal and large neurogenic MUPs. It identifies features related to the sound produced by the MUP on the audio monitor, which is often used by trained electromyographers for qualitative assessments of MUPs. © 2002 Wiley Periodicals, Inc. Muscle Nerve Supplement 11: S98,S102, 2002 [source]


Conundrums of competitive ability in plants: what to measure?

OIKOS, Issue 3 2002
LonnieW.
A survey of recent literature indicates that competitive ability in plants has been measured, in most studies, only in terms of the relative intensity of size suppression experienced by competitors within one growing season. Far fewer studies have recorded relative success in terms of survival and even fewer studies have recorded fecundity under competition. Differences in size suppression are usually assumed to reflect differences in relative abilities to deny resources to competitors. However, most previous studies have failed to control or account for other sources of variation in the size suppression that plants experience under competition, i.e. variation between mixtures in the resource supply/demand ratio (approach to carrying capacity), or variation in the degree of niche overlap between competitors, or variation in the intensity of concurrent facilitative interactions between competitors. For future studies, much greater caution is required in recognizing these inherent limitations of traditional measures of competitive ability and, hence, guarding against unfounded conclusions or predictions about potential for competitive success that are based on these measures. There is also a significant challenge for future studies to adopt empirical approaches for minimizing these limitations. Some initial recommendations are considered here based on an emerging view of competitive ability measured in terms of traits associated with all three conventional components of Darwinian fitness, i.e. not just growth (plant size) but also survival and fecundity allocation (offspring production per unit plant size per unit time). According to this model, differences in competitive ability imply differences in the ability, despite intense competition (i.e. low resource supply/demand ratio), to recruit offspring into the next generation and thereby limit offspring recruitment by other plants. The important traits of competitive ability, therefore, are not only those that allow a plant to deny resources to competitors, suppress their sizes and hence, maximize the plant's own size, but also those traits that allow the plant to withstand suppression from competition enough to persist, both as an individual (through survival) and across generations (through descendants). [source]


Phased-Array Intracardiac Echocardiography for Guiding Transseptal Catheter Placement: Utility and Learning Curve

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2002
SUSAN B. JOHNSON
JOHNSON, S.B., et al.: Phased-Array Intracardiac Echocardiography for Guiding Transseptal Catheter Placement: Utility and Learning Curve. The utility of a new intracardiac 64-element, phased-array, longitudinal ultrasound imaging system for guiding transseptal catheterization was assessed during 69 crossing attempts in 45 dogs because of the inherent limitations of fluoroscopy and mechanical ultrasound. Multifrequency (7.5,8.5 MHZ) imaging of the membranous fossa ovalis, posterior left atrium, and left atrial appendage was conducted from the right atrium. Contact of the Brockenbrough needle with the interatrial septum as reflected by membranous fossa ovalis "tenting" was uniformly identified. Transseptal crossing and advancement of the dilator and sheath were adequately imaged because of deeper ultrasound tissue penetration. Transseptal catheterization was successfully accomplished in 44 of 45 dogs: on the first attempt in 40 and with additional attempts in 4 and confirmed by direct far-field imaging of nonagitated saline injection via the sheath. Total transseptal catheterization time was 3.0 ± 1.8 minutes. Unsuccessful first attempts and/or subsequent sheath pullback into the right atrium with catheter manipulation were also readily recognized. Insertion of the transseptal needle beyond the ultrasound imaging plane resulted in perforation of the posterior left atrial wall in three attempts. Accompanying effusions in these animals and three others related to subsequent intracardiac ablation catheter manipulation were readily identified and monitored echocardiographically. In conclusion, phased-array intracardiac imaging provides a highly reliable means of guiding transseptal access to the left atrium. In addition, inadvertent complications such as perforation and pericardial effusion development can be readily recognized. [source]


Quantum dot-tagged microspheres for fluid-based DNA microarrays

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003
K. E. Meissner
Abstract Quantum dot-embedded microspheres offer a promising technology for the development of a fluid-based DNA microarray to replace current biochip microarray technology. The narrow emission and long lifetime from the quantum dots (QD's) is ideal for dense spectral multiplexing. Also, the QD's may all be excited by a single source. To implement this solution, we have fabricated CdSe quantum dots following published procedures and embedded them in polystyrene microspheres. As a first step in this development, we have investigated the use of a flow cytometer in analyzing the encoded microspheres. We demonstrate the use of a microsphere-based DNA detection system and investigate the readout of quantum dot-tagged microspheres. We also discuss some of the inherent limitations and difficulties of using such a system to address the need for a high-throughput readout for spectral multiplexing for fluid-based DNA microarrays. [source]


Agrobacterium -mediated transformation of cereals: a promising approach crossing barriers

PLANT BIOTECHNOLOGY JOURNAL, Issue 6 2006
Ashok Kumar Shrawat
Summary Cereal crops have been the primary targets for improvement by genetic transformation because of their worldwide importance for human consumption. For a long time, many of these important cereals were difficult to genetically engineer, mainly as a result of their inherent limitations associated with the resistance to Agrobacterium infection and their recalcitrance to in vitro regeneration. The delivery of foreign genes to rice plants via Agrobacterium tumefaciens has now become a routine technique. However, there are still serious handicaps with Agrobacterium -mediated transformation of other major cereals. In this paper, we review the pioneering efforts, existing problems and future prospects of Agrobacterium -mediated genetic transformation of major cereal crops, such as rice, maize, wheat, barley, sorghum and sugarcane. [source]


Virtual team concepts in projects: A case study

PROJECT MANAGEMENT JOURNAL, Issue 2 2009
Palitha R. Kuruppuarachchi
Abstract This article uses a case study to demonstrate the application of virtual team concepts in a virtual project team formed from existing personnel within an organization. The article is presented as a literature review followed by a case study of a virtual team project entitled the "Country Capital Works Program" undertaken within the New South Wales Police Force, Australia. The case confirms the appropriateness of existing virtual team concepts in a virtual project team formed from existing personnel for a specific purpose. The study has the inherent limitations of any case study in terms of the generalization of the findings. [source]


Strategic Human Resource Practices: Introducing Alternatives for Organizational Performance Improvement in the Public Sector

PUBLIC ADMINISTRATION REVIEW, Issue 1 2010
Jungin Kim
Can public sector organizations increase productivity through competition in spite of inherent limitations, such as budget constraints? This study addresses that question by examining the impact of four factors that contribute to employees' expectations regarding competitive work environments on organizational performance in terms of overall quality of work and client satisfaction. The four factors measured include rewards for merit such as salary and benefits, opportunities, organizational rules, and the capacity to deal with risks as perceived by employees. Using data on public and nonprofit sector employees, expectations for merit rewards were positively related to employees' perception of organizational performance when the conditions of performance-based organizational rules and risk-taking behaviors were also satisfied. Moreover, employees' perceptions of organizational performance tended to increase when they felt that organizational rules were oriented toward performance plus organizational members and top leaders exhibited greater risk-taking behaviors. However, no correlation was evident between employees' expectations of opportunities and perceived organizational performance. [source]


Estimating tobacco consumption in remote Aboriginal communities using retail sales data: some challenges and opportunities

AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 2010
David MacLaren
Abstract Objective: To describe and discuss challenges and opportunities encountered when estimating tobacco consumption in six remote Aboriginal communities using tobacco sales data from retail outlets. Approach: We consider tobacco sales data collected from retail outlets selling tobacco to six Aboriginal communities in two similar but separate studies. Despite challenges , including: not all outlets provided data; data not uniform across outlets (sales and invoice data); change in format of data; personnel change or management restructures; and anomalies in data and changes in community populations , tobacco consumption was estimated and returned through project newsletters and community feedback sessions. Amounts of tobacco sold were returned using graphs in newsletters and pictures of items common to the community in community feedback sessions. Conclusions: Despite inherent limitations of estimating tobacco consumption using tobacco sales data, returning the amount of tobacco sold to communities provided an opportunity to discuss tobacco consumption and provide a focal point for individual and community action. Using this method, however, may require large and sustained changes be observed over time to evaluate whether initiatives to reduce tobacco consumption have been effective. Implications: Estimating tobacco consumption in remote Aboriginal communities using tobacco sales data from retail outlets requires careful consideration of many logistical, social, cultural and geographic challenges. [source]