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Complex Phenomenon (complex + phenomenon)
Selected AbstractsNecrotizing vasculitis in a patient affected by autoimmune hyperthyroidism treated with propylthiouracilDERMATOLOGIC THERAPY, Issue 2010Angela Antonucci ABSTRACT Necrotizing vasculitis is a complex phenomenon because of an inflammation of small and larger vessels with polymorph infiltration within the vessel walls and leukocytoclasis, occurring in several autoimmune diseases. Propylthiouracil (PTU) is a medication commonly used to treat hyperthyroidism, but it is associated with various rare side effects, such as antineutrophil cytoplasm antibody-positive vasculitis. In the last decades, multiple cases of PTU causing antineutrophilic cytoplasmic antibody have been reported, some of them fatal. The present authors report the case of a 34-year-old Caucasian female affected by autoimmune hyperthyroidism treated with PTU, presenting an antineutrophil cytoplasm antibody-positive necrotizing vasculitis, with high levels of anticardiolipin antibodies that involved the upper arms and buttocks. The clinical manifestations improved after discontinuing of PTU and immunosuppressant treatment. [source] Persistent poor glycaemic control in adult Type 1 diabetes.DIABETIC MEDICINE, Issue 12 2004A closer look at the problem Abstract Around 25% of the adult Type 1 diabetes population is in persistent poor glycaemic control and thus at increased risk of developing microvascular complications. We here discuss correlates of long-standing poor glycaemic control and review the efficacy of clinical strategies designed to overcome persistent poor control. Only a few studies have identified determinants and correlates of long-standing poor glycaemic control in Type 1 diabetes. There is some evidence implicating genetic factors, as well as lower economic status, and psychological factors, including lack of motivation, emotional distress, depression and eating disorders. Ways of improving glycaemic control include strategies to enable self-management, e.g. motivational strategies, coping-orientated education, psychosocial therapies, and/or intensifying insulin injection therapy plus continuous subcutaneous insulin infusion. Long-standing poor glycaemic control appears to be a heterogeneous and complex phenomenon, for which there is no simple, single solution. Comprehensive psycho-medical assessment in diabetes care may prove useful in tailoring interventions. Further research is warranted, to increase our understanding how psychosocial and biomedical factors, separately and in interaction, determine poor outcomes in Type 1 diabetes. [source] Land-cover and land-use change and its contribution to the large-scale organization of Puerto Rico's bird assemblagesDIVERSITY AND DISTRIBUTIONS, Issue 1 2008Miguel A. Acevedo ABSTRACT Global biodiversity is changing rapidly driven by human alteration of habitat, and nowhere this is more dramatic than in insular habitats. Yet land-cover change is a complex phenomenon that not only involves habitat destruction but also forest recovery over different time scales. Therefore, we might expect species to respond in diverse ways with likely consequences for the reorganization of regional assemblages. These changes, however, may be different in tropical islands because of their low species richness, generalist habits and high proportion of endemics. Here, we focus on the island of Puerto Rico and ask how island-wide changes in land cover and land use has influenced the large-scale organization of bird assemblages. To address this question, we combined in a Geographical Information System (GIS) the first 6 years (1997,2002) of the Puerto Rican Breeding Bird Survey (PR-BBS) with land-cover and land-use data extracted from a published digital map derived from the classification of Landsat images. A Non-metric Multidimensional Scaling (NMS) ordination based on the composition and abundance of birds, and percentage land-use types showed that land use followed by climate could explain most of the variation observed among routes in terms of species composition and abundance. Moreover, endemic and exotic species were widely distributed throughout the island, but the proportion of endemic species is higher in closed forests while exotic species are more abundant in open habitats. However, historical accounts from the early 1900s indicate that endemic species were distributed across the entire island. Today, most of the land cover transformation in Puerto Rico occurs in the lowlands which may explain the high abundance of endemic species in cloud forests and the high abundance of exotic species in open habitats in the lowlands. [source] Bentazon triggers the promotion of oxidative damage in the Portuguese ricefield cyanobacterium Anabaena cylindrica: Response of the antioxidant systemENVIRONMENTAL TOXICOLOGY, Issue 5 2010Victor Galhano Abstract Rice fields are frequently exposed to environmental contamination by herbicides and cyanobacteria, as primary producers of these aquatic ecosystems, are adversely affected. Anabaena cylindrica is a cyanobacterium with a significantly widespread occurrence in Portuguese rice fields. This strain was studied throughout 72 h in laboratory conditions for its stress responses to sublethal concentrations (0.75,2 mM) of bentazon, a selective postemergence herbicide recommended for integrated weed management in rice, with special reference to oxidative stress, role of proline and intracellular antioxidant enzymes in herbicide-induced free radicals detoxification. Activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione S -transferase (GST) increased in a time- and herbicide dose-response manner and were higher than those in the control samples after 72 h. A time- and concentration-dependent increase of malondialdehyde (MDA) levels and the enhanced cell membrane leakage following bentazon exposure are indicative of lipid peroxidation, free radicals formation, and oxidative damage, while increased amounts of SOD, CAT, APX, GST, and proline indicated their involvement in free radical scavenging mechanisms. The appreciable decline in the reduced glutathione (GSH) pool after 72 h at higher bentazon concentrations could be explained by the reduction of the NADPH-dependent glutathione reductase (GR) activity. The obtained results suggested that the alterations of antioxidant systems in A. cylindrica might be useful biomarkers of bentazon exposure. As the toxic mechanism of bentazon is a complex phenomenon, this study also adds relevant findings to explain the oxidative stress pathways of bentazon promoting oxidative stress in cyanobacteria. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010. [source] Probabilistic risk modeling at the wildland urban interface: the 2003 Cedar FireENVIRONMETRICS, Issue 6 2009D. R. Brillinger Abstract The October 2003 Cedar Fire in San Diego County was a tragedy involving 15 deaths, the burning of some 280,000,acres of land, the destruction of approximately 2227 homes, and costs of suppression near $30 million. It was the largest fire in California history. The data associated with the fire, however, do provide an opportunity to carry out probabilistic risk modeling of a wildland-urban interface (WUI) event. WUI's exist where humans and their development interface with wildland fuel. As home building expands from urban areas to nearby forest areas, these homes become more likely to burn. Wildfires are an exceedingly complex phenomenon with uncertainty and unpredictability abounding, hence a statistical approach to gaining insight appears useful. In this research, spatial stochastic models are developed. These relate risk probabilities and losses measures to a variety of available explanatory quantities. There is a consideration of economic aspects and a discussion of the difficulties that arose in developing the data and of carrying out the analyses. Purposes of the work include highlighting a statistical method, developing variates associated with a destruction probability and employing the fitted risk probability to estimate future and possible losses. Copyright © 2008 John Wiley & Sons, Ltd. [source] 7-Ketocholesterol-induced apoptosisFEBS JOURNAL, Issue 12 2005Involvement of several pro-apoptotic but also anti-apoptotic calcium-dependent transduction pathways Oxysterols, and particularly 7-ketocholesterol, appear to be strongly involved in the physiopathology of atherosclerosis. These molecules are suspected to be cytotoxic to the cells of the vascular wall and monocytes/macrophages, particularly by inducing apoptosis. Previous studies have demonstrated that 7-ketocholesterol-induced apoptosis is triggered by a sustained increase of cytosolic-free Ca2+, which elicits the mitochondrial pathway of apoptosis by activation of the calcium-dependent phosphatase calcineurin, leading to dephosphorylation of the ,BH3 only' protein BAD. However, thorough study of the results suggests that other pathways are implicated in 7-ketocholesterol-induced cytotoxicity. In this study, we demonstrate the involvement of two other calcium-dependent pathways during 7-ketocholesterol-induced apoptosis. The activation of the MEK,ERK pathway by the calcium-dependent tyrosine kinase PYK 2, a survival pathway which delays apoptosis as shown by the use of the MEK inhibitor U0126, and a pathway involving another pro-apoptotic BH3 only protein, Bim. Indeed, 7-ketocholesterol treatment of human monocytic THP-1 cells induces the release of Bim-LC8 from the microtubule-associated dynein motor complex, and its association with Bcl-2. Therefore, it appears that 7-ketocholesterol-induced apoptosis is a complex phenomenon resulting from calcium-dependent activation of several pro-apoptotic pathways and also one survival pathway. [source] Porins of Pseudomonas fluorescens MFO as fibronectin-binding proteinsFEMS MICROBIOLOGY LETTERS, Issue 1 2002J. Rebière-Huët Abstract Bacterial adherence is a complex phenomenon involving specific interactions between receptors, including matricial fibronectin, and bacterial ligands. We show here that fibronectin and outer membrane proteins of Pseudomonas fluorescens were able to inhibit adherence of P. fluorescens to fibronectin-coated wells. We identified at least six fibronectin-binding proteins with molecular masses of 70, 55, 44, 37, 32 and 28 kDa. The presence of native (32 kDa) and heat-modified forms (37 kDa) of OprF was revealed by immuno-analysis and the 44-kDa band was composed of three proteins, their N-terminal sequences showing homologies with Pseudomonas aeruginosa porins (OprD, OprE1 and OprE3). [source] Identifying interacting predictors of falling among hospitalized elderly in Japan: A signal detection approachGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 2 2007Atsuko Nabeshima Falling is a complex phenomenon that involves interaction of multiple risk factors. The authors analyzed factors related to falls in a geriatric hospital to elucidate interaction of multiple risk factors for falls in elderly inpatients. Subjects were 364 patients (mean age, 81.7; women 76.7%) who were aged 60 years and over and had been hospitalized for more than 6 months between April 2000 and March 2001. A signal detection model was used to identify baseline variables that best divided the sample into subgroups using incidence of falling as an outcome variable. During a follow-up period, 91 patients (25%) had at least one incident of fall. Out of 14 independent variables, a higher-order interaction consisting of six significant variables was identified. Consequently, the subjects were categorized into seven subgroups whose fall rate varied 5.7,80.9%. We found that the combination of non-bedridden state, dementia, and medication of tranquilizers or sleeping drugs was the highest fall rate (80.9%). Signal detection analysis is useful to identify the combination of multiple risk factors of falling, and applicable to develop prevention programs for each subgroups. [source] Structure,Property,Function Relationships in Nanoscale Oxide Sensors: A Case Study Based on Zinc Oxide,ADVANCED FUNCTIONAL MATERIALS, Issue 8 2007S. Polarz Abstract Chemical sensing on oxide sensors is a complex phenomenon involving catalytic activity as well as electronic properties. Thus, the properties of oxide sensors are highly sensitive towards structural changes. Effects like surface area, grain size, and, in addition, the occurrence of defects give separate contributions to the current. Structure,property,function relationships can be elucidated using a combination of state-of-the-art analytical techniques. It is shown, that impurity atoms in the oxide lattice influence the performance of ZnO sensors more strongly than the other factors. [source] A micromechanical study of rolling and sliding contacts in assemblies of oval granulesINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 5 2003Hossein M. Shodja Abstract The evolution of the microstructure of an assembly of cohesionless granular materials with associated pores, which carry the overall applied stresses through frictional contacts is a complex phenomenon. The macroscopic flow of such materials take place by the virtue of the relative rolling and sliding of the grains on the micro-scale. A new discrete element method for biaxial compression simulations of random assemblies of oval particles with mixed sizes is introduced. During the course of deformation, the new positions of the grains are determined by employing the static equilibrium equations. A key aspect of the method is that, it is formulated for ellipse cross-sectional particles, hence desirable inherent anisotropies are possible. A robust algorithm for the determination of the contact points between neighbouring grains is given. Employing the present methodology, many aspects of the behaviour of two-dimensional assemblies of oval cross-sectional rods have been successfully addressed. The effects of initial void ratio, interparticle friction angle, aspect ratio, and bedding angle on the rolling and sliding contacts are examined. The distribution of normals to the rolling and sliding contacts have different patterns and are concentrated along directions, which are approximately perpendicular to one another. On the other hand, the distribution of all contact normals (combined rolling and sliding) are close to that of rolling contacts, which confirm that rolling is the dominant mechanism. This phenomenon becomes more pronounced for higher intergranular friction angle. Characteristics of the rolling and sliding contacts are also discussed in the context of the force angle, which is the inclination of contact force with respect to the contact normal. Copyright © 2003 John Wiley & Sons, Ltd. [source] Adaptive through-thickness integration for accurate springback predictionINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2008I. A. Burchitz Abstract Accurate numerical prediction of springback in sheet metal forming is essential for the automotive industry. Numerous factors influence the accuracy of prediction of this complex phenomenon by using the finite element method. One of them is the numerical integration through the thickness of shell elements. It is known that the traditional numerical schemes are very inefficient in elastic,plastic analysis and even for simple problems they require up to 50 integration points for an accurate springback prediction. An adaptive through-thickness integration strategy can be a good alternative. The main characteristic feature of the strategy is that it defines abscissas and weights depending on the integrand's properties and, thus, can adapt itself to improve the accuracy of integration. A concept of an adaptive through-thickness integration strategy for shell elements is presented in this paper. Its potential is demonstrated using two examples. Calculations of a simple test,bending a beam under tension,show that for a similar set of material and process parameters the adaptive rule with seven integration points performs significantly better than the traditional trapezoidal rule with 50 points. Simulations of an unconstrained cylindrical bending problem demonstrate that the adaptive through-thickness integration strategy for shell elements can guarantee an accurate springback prediction at minimal costs. Copyright © 2007 John Wiley & Sons, Ltd. [source] Suffering related to health care: A study of breast cancer patients' experiencesINTERNATIONAL JOURNAL OF NURSING PRACTICE, Issue 6 2004Maria Arman RNM PhD A previous study indicated that patient narratives include experiences of suffering caused or increased by health-care encounters. The aim of this study was to interpret and understand the meaning of patients' experiences of suffering related to health care from an ethical, existential and ontological standpoint. Sixteen women with breast cancer in Sweden and Finland took part in qualitative interviews analysed with a hermeneutic, interpretive approach. The outcome showed that suffering related to health care is a complex phenomenon and constitutes an ethical challenge to health-care personnel. The women's experiences of suffering related to health care tended to be of similar seriousness as their experiences of suffering in relation to having cancer. In an ethical, existential and ontological sense, suffering related to health care is basically a matter of neglect and uncaring where the patient's existential suffering is not seen and she is not viewed as a whole human being. [source] International perspectives on workplace bullying among nurses: a reviewINTERNATIONAL NURSING REVIEW, Issue 1 2009S.L. Johnson rn Purpose:, This article examines the nursing literature on workplace bullying with the aim of reaching a better understanding of the phenomenon. Background:, Workplace bullying occurs in many occupations and workplaces, including nursing. Methods:, The following databases were used for the literature review: CINAHL, PubMed, Pro Quest and EBSCO host. Only articles in English were used. Articles from outside the nursing literature were also examined to gain a broader understanding of workplace bullying. Findings:, Workplace bullying is more than a simple conflict between two individuals. It is a complex phenomenon that can only be understood through an examination of social, individual and organizational factors. Workplace bullying has been shown to impact the physical and psychological health of victims, as well as their performance at work. Workplace bullying impacts the organization through decreased productivity, increased sick time and employee attrition. Conclusions:, More nurse-specific research is needed in this area. Research needs to be conducted in a systematic and uniform manner so that generalizations across studies can be made. The ultimate goal of this research should be to generate an understanding of this phenomenon so that solutions can be found. [source] The Reliability, Validity and Practical Utility of Measuring Supports using the I-CAN Instrument: Part IIJOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES, Issue 4 2009Vivienne C. Riches Background, There is an urgent need for developing reliable, valid and practical instruments that assess and classify the support needed by persons with disability to function in their chosen living, working and social environments. I-CAN is an instrument that addresses the frequency and level of support needed (not individual skills or deficits) for each individual with a disability. Method, Studies were conducted to assess the test,retest reliability and inter-rater reliability. Concurrent validity was investigated by exploring the relationship between the I-CAN domain scales and the Inventory for Client and Agency Planning (ICAP) (Bruininks et al. 1986) and the Quality of Life Questionnaire (QOL-Q) (Schalock & Keith 1993). Predictive validity studies were undertaken using day- and night-time support hours. Regression analyses were run using these measures with I-CAN domain scales. Two independent studies were also conducted to ascertain the practical utility of the instrument. Results, The I-CAN instrument demonstrated excellent inter-rater and test,retest reliability in the Activities and Participation domains. Low-to-moderate test,retest results in Physical Health, Mental Emotional Health and Behaviour domains were tracked to actual change in support needs in these areas. Validity proved acceptable. The relationships between I-CAN domain scales and adaptive behaviour were mixed but in the expected direction. Low-to-moderate correlation coefficients were evident between the I-CAN scales and the QOL-Q Total, but greater support needed in certain domains was associated with less empowerment and independence, and less community integration and social belonging. Attempts to explain current support hours against the I-CAN scales were disappointing and suggest that a number of other factors apart from individual support need to play a significant role. There was general satisfaction with the assessment process from stakeholders and participant groups. Conclusions, I-CAN is a reliable, valid and user-friendly instrument for assessing the support needs of people with disabilities. It uses a process that involves the persons with disability, their family and friends and staff as appropriate. It is also apparent that the current provision of paid support hours by agencies is a complex phenomenon that is not based solely on individual support needs. Further research is warranted on the influence of the environment and the perceptions of need for support based on negotiable and non-negotiable support needs. [source] Indices for studying urinary incontinence and levator ani function in primiparous womenJOURNAL OF CLINICAL NURSING, Issue 4 2003Cathy L. Antonakos PhD Summary ,,Urinary incontinence (UI) is a complex phenomenon that is prevalent in pregnant and parous women and requires the use of sophisticated measures to adequately reflect functioning of the continence system. ,,The purpose of this study was to develop reliable and valid measures of UI and levator ani function for use in research and clinical settings. ,,A Leakage Index (LI) and a Levator Ani Function Index (LAFI) were developed using data from a longitudinal study of primiparous women. Reliability and validity tests were conducted to: (i) estimate the internal consistency reliability of each index, (ii) determine whether the indices captured change in continence status and pelvic floor function during pregnancy through 1 year postpartum, and (iii) estimate association between the indices as a test of predictive validity. ,,Cronbach's alpha ranged from 0.72 to 0.84 for the LI and from 0.53 to 0.79 for the LAFI across the six data collection time points of the study. Average LI scores increased late in pregnancy and decreased postpartum, though not significantly. Average LAFI scores decreased significantly at 35 weeks gestation (t = 4.84, P = 0.000) and increased significantly at 12 months postpartum (t = ,3.51, P = 0.002) relative to baseline. The LI and LAFI were significantly associated at 20 weeks gestation (Pearson r = ,0.40, P = 0.007) and at 6 weeks postpartum (Pearson r = ,0.33, P = 0.029). ,,The findings suggest the LI and LAFI are reliable and valid measures of UI and levator ani function in primiparous women, which can be used with confidence in clinical and research settings. [source] Lived experiences of eating problems for patients with head and neck cancer during radiotherapyJOURNAL OF CLINICAL NURSING, Issue 4 2003Maria Larsson MNSc Summary ,,Only a small proportion of cancer patients undergo radical radiotherapy to the head and neck, but their needs are particularly complex. Although extensive research describes the side-effects of radiotherapy to the head and neck, few studies focus on patients' subjective experiences of eating problems and the impact these have on the patients' daily life. ,,In this study a phenomenological approach was used, as the purpose was to acquire deeper understanding of head and neck cancer patients' lived experiences of eating problems, their consequences in daily life and patients' strategies of coping with these problems. ,,Eight patients from two radiation therapy departments in mid-Sweden were interviewed in an open dialogue. Data analysis was based on Colaizzi's method. ,,Eating problems experienced were captured in two interrelated main themes: ,Ability to chew and swallow' and ,Will and desire to eat'. The eating problems were found to cause a number of severe consequences in daily life. These are incorporated into one main theme: ,The way of life is disturbed'. Ways to cope with this disturbance were captured in one main theme: ,Trying to see the end , To survive'. ,,This study identifies the need to view eating problems as a complex phenomenon in a specific context including the individual patient's life situation. The findings create the opportunity to develop nursing interventions based on patients' own needs. To facilitate this, a specialist nurse should be responsible for reviewing patients regularly throughout radiation therapy. Intervention studies are needed to provide optimal clinical guidelines. [source] Towards a sustainable theory of health-related stigma: lessons from the HIV/AIDS literatureJOURNAL OF COMMUNITY & APPLIED SOCIAL PSYCHOLOGY, Issue 6 2006Harriet Deacon Abstract Stigma has been identified as a major barrier to health care and quality of life in illness management. But unfortunately there is no common theoretical perspective on stigma. We need a sustainable theory of health-related stigma. This would start with a coherent definition of stigma that brings together both individual and social dimensions of this complex phenomenon. It would reassesses the existence of ,types' of stigma and explain how stigma relates to disadvantage. A sustainable theory would help researchers to move from theory into practice: to develop a comprehensive measurement tool for stigma and related disadvantage, and inform design, monitoring and evaluation of anti-stigma interventions. This paper draws on two recent literature reviews on HIV/AIDS stigma to introduce several key issues in developing a sustainable theory of stigma. We suggest limiting the definition of stigma to the process of othering, blaming and shaming (often called symbolic stigma). We argue that there is value in analytically separating stigma from discrimination in order to better understand the relationship between them. We also suggest the need to understand discrimination caused by stigma as only one element of stigma-related disadvantage. Copyright © 2006 John Wiley & Sons, Ltd. [source] Ab initio computational study of positron emission tomography ligands interacting with lipid molecule for the prediction of nonspecific bindingJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 14 2008Lula Rosso Abstract Nonspecific binding is a poorly understood biological phenomenon of relevance in the study of small molecules interactions in vivo and in drug development. Nonspecific binding is thought to be correlated in part to a molecule's lipophilicity, typically estimated by measuring (or calculating) octanol,water partition coefficient. This is, however, a gross simplification of a complex phenomenon. In this article, we present a computational method whose aim is to help identify positron emission tomography (PET) ligands with low nonspecific binding characteristics by investigating the molecular basis of ligand,membrane interaction. We considered a set consisting of 10 well-studied central nervous system PET radiotracers acting on a variety of molecular targets. Quantum mechanical calculations were used to estimate the strength of the interaction between each drug molecule and one phospholipid molecule commonly present in mammalian membranes. The results indicate a correlation between the computed drug,lipid interaction energy and the in vivo nonspecific distribution volume relative to the free tracer plasma concentration, calculated using standard compartmental modeling for the analysis of PET data. Significantly, the drugs whose interaction with the lipid molecule more favorably possessed, in general, a higher nonspecific binding value, whereas for the drugs taken in consideration in this study, the water-octanol partition coefficient, log P, did not show good predictive power of the nonspecific binding. This study also illustrates how ab initio chemical methods may offer meaningful and unbiased insights for the understanding of the underlying chemical mechanisms in biological systems. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] Tissue-specific dysregulation of DNA methylation in agingAGING CELL, Issue 4 2010Reid F. Thompson Summary The normal aging process is a complex phenomenon associated with physiological alterations in the function of cells and organs over time. Although an attractive candidate for mediating transcriptional dysregulation, the contribution of epigenetic dysregulation to these progressive changes in cellular physiology remains unclear. In this study, we employed the genome-wide HpaII tiny fragment enrichment by ligation-mediated PCR assay to define patterns of cytosine methylation throughout the rat genome and the luminometric methylation analysis assay to measure global levels of DNA methylation in the same samples. We studied both liver and visceral adipose tissues and demonstrated significant differences in DNA methylation with age at > 5% of sites analyzed. Furthermore, we showed that epigenetic dysregulation with age is a highly tissue-dependent phenomenon. The most distinctive loci were located at intergenic sequences and conserved noncoding elements, and not at promoters nor at CG-dinucleotide-dense loci. Despite this, we found that there was a subset of genes at which cytosine methylation and gene expression changes were concordant. Finally, we demonstrated that changes in methylation occur consistently near genes that are involved in metabolism and metabolic regulation, implicating their potential role in the pathogenesis of age-related diseases. We conclude that different patterns of epigenetic dysregulation occur in each tissue over time and may cause some of the physiological changes associated with normal aging. [source] Polymerization Contraction Stress of Resin Composite Restorations in a Model Class I Cavity Configuration Using Photoelastic AnalysisJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 6 2000YOSHIFUMI KINOMOTO DDS ABSTRACT Purpose: An important factor that contributes to deterioration of resin composite restorations is contraction stress that occurs during polymerization. The purpose of this article is to familiarize the clinician with the characteristics of contraction stress by visualizing the stresses associated with this invisible and complex phenomenon. Materials and Methods: Internal residual stresses generated during polymerization of resin composite restorations were determined using micro-photoelastic analysis. Butt-joint preparations simulating Class I restorations (2.0 mm ± 5.0 mm, 2.0 mm in depth) were prepared in three types of substrates (bovine teeth, posterior composite resin, and transparent composite resin) and were used to examine contraction stress in and around the preparations. Three types of composite materials (a posterior composite, a self-cured transparent composite, and a light-cured transparent composite) were used as the restorative materials. The self-cured composite is an experimental material, and the others are commercial products. After treatment of the preparation walls with a bonding system, the preparations were bulk-filled with composite. Specimens for photo-elastic analysis, were prepared by cutting sections perpendicular to the long axis of the preparation. Fringe patterns for directions and magnitudes of stresses were obtained using transmitted and reflected polarized light with polarizing microscopes. Then, the photoelastic analysis was performed to examine stresses in and around the preparations. Results: When cavity preparations in bovine teeth were filled with light-cured composite, a gap was formed between the dentinal wall and the composite restorative material, resulting in very low stress within the restoration. When cavity preparations in the posterior composite models were filled with either self-cured or light-cured composite, the stress distribution in the two composites was similar, but the magnitude of the stress was greater in the light-cured material. When preparations in the transparent composite models were filled with posterior composite and light-cured transparent composite material, significant stress was generated in the preparation models simulating tooth structure, owing to the contraction of both restorative materials. CLINICAL SIGNIFICANCE Polymerization contraction stress is an undesirable and inevitable characteristic of adhesive restorations encountered in clinical dentistry that may compromise restoration success. Clinicians must understand the concept of polymerization contraction stress and realize that the quality of composite resin restorations depends on successful management of these stresses. [source] Pre-mRNA splicing modulations in senescenceAGING CELL, Issue 1 2002Eran Meshorer Summary Aging and associated diseases involve multilevel changes in the complex phenomenon of alternative splicing. Here, we review the potential genomic and environmental origins of such changes and discuss the research implications of these findings. [source] Cloning and expression profile of FLT3 gene during progenitor cell-dependent liver regenerationJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 12 2007Iraz T Aydin Abstract Background and Aim:, The liver has a unique capacity to regenerate upon exposure to viral infections, toxic reactions and cancer formation. Liver regeneration is a complex phenomenon in which several factors participate during its onset. Cellular proliferation is an important component of this process and the factors that regulate this proliferation have a vital role. FLT3, a well-known hematopoietic stem cell and hepatic lineage surface marker, is involved in proliferative events of hematopoietic stem cells. However, its contribution to liver regeneration is not known. Therefore, the aim of this study was to clone and examine the role of FLT3 during liver regeneration in rats. Methods:, Partial cDNA of rat homolog of FLT3 gene was cloned from thymus and the tissue specific expression of this gene at mRNA and protein levels was examined by RT-PCR and Western blot. After treating with 2-AAF and performing hepatectomy in rats to induce progenitor-dependent liver regeneration, the mRNA and protein expression profile of FLT3 was investigated by real-time PCR and Western blot during liver regeneration. In addition, cellular localization of FLT3 protein was determined by immunohistochemistry. Results:, The results indicated that rat FLT3 cDNA has high homology with mouse and human FLT3 cDNA. It was also found that FLT3 is expressed in most of the rat tissues and during liver regeneration. In addition, its intracellular localization is altered during the late stages of liver regeneration. Conclusion:, The FLT3 receptor is activated at the late stages of liver regeneration and participates in the proliferation response that is observed during progenitor-dependent liver regeneration. [source] Colloid-Associated contaminant transport in porous media: 1.AICHE JOURNAL, Issue 10 2002Experimental studies Many studies have identified colloid-associated transport of contaminants as an important mechanism of contaminant migration through groundwater. It is a complex phenomenon in porous media involving several basic processes such as adsorption of contaminants, release and migration of colloidal fines, and entrapment of fines at the pore constrictions. The effects of these basic processes on the contaminant transport are studied. Column experiments are conducted to study the effects of the mobilization and migration of colloidal fines, kaolin on the transport of contaminant, and Ni2+ metal ion through the sand beds containing kaolin particles under both nonplugging and plugging conditions. As reported in literature, colloidal fines can facilitate the contaminant transport when they migrate with the flow. In the absence of migration, kaolin-sand beds retard Ni2+ transport in comparison to sand beds due to their higher adsorption capacity, but the sand-kaolin composite bed acts like an inefficient adsorption column with percentage saturation (which is in general below 25%). It is interesting to note that under plugging conditions, which can be induced by using a lower bead size to particle-size ratio, the breakthrough curves are more flattened and delayed at a higher kaolin content of the bed. [source] Early cinematographic studies of generalized dystoniaMOVEMENT DISORDERS, Issue 10 2006Christopher G. Goetz MD Abstract Among movement disorders, dystonia is a particularly complex phenomenon and difficult to describe. For this reason, cinematographic documents were particularly important to the establishment of this disorder within the neurological nosology. The seminal 1944 article on dystonia by E. Herz anchored its arguments in moving film documentation, published with frame-by-frame demonstrations of dystonic patients. Although the original films that comprised the basis of this article have not been located, two related contemporaneous films, one by Herz in association with T.J. Putnam, and one by S.P. Goodhart and B.H. Balser, have been located. Incorporating standard and several innovative filming techniques, these films and their accompanying text material capture the particular movements of dystonia, revealing the anatomical patterns of the twisting spasms, and emphasize their action exacerbation. The films demonstrate the variety of dystonic movements appreciated during this period, consider psychogenic, postencephalitic, and hereditary forms, and refer to the treatment of dystonia by surgery and plaster casts. © 2006 Movement Disorder Society [source] Web-based Health Survey Systems in Outcome Assessment and Management of PainPAIN MEDICINE, Issue 2007Vinod K. Podichetty MD ABSTRACT Pain is a complex phenomenon lacking a well-defined paradigm for diagnosis and management across medical disciplines. This is due in part to inconsistencies in the assessment of pain as well as in the measurement of related social and psychological states. Efforts to evaluate and measure pain through objective tests have been hindered by challenges such as methodological differences in data acquisition, and the lack of common, universally accepted information systems. Physicians and hospital administrators have expressed mixed reactions to the costs that inevitably accompany advances in medical technology. Nonetheless, computer systems are currently being developed for use in the quantitative assessment and management of pain, which can advance our understanding of the public health impact of pain, improve the care individual patients receive, and educate providers. The description of an interdisciplinary, integrated, health survey system illustrates the approach and highlights the advantages of using information technology in pain evaluation and management. [source] Relative viscosity models and their application to capillary flow data of highly filled hard-metal carbide powder compoundsPOLYMER COMPOSITES, Issue 1 2005Tomas Honek The rheological behavior of highly filled polymer systems used in powder injection molding (PIM) technology strongly influences the final properties of the products. In this study, the capillary flow data of multi-component polymer binders,based on polyethylene, paraffin, ethylene-based copolymers, and polyethylene glycol,compounded with three various hard-metal carbide powders were employed. The rheology of such highly filled (up to 50 vol%) multiphase systems is necessarily a complex phenomenon characterized by strain dependent, non-Newtonian properties complicated by flow instabilities and yield. Over 15 mathematical models proposed for highly filled systems were tested, some of them calculating the maximum filler loading. Due to the complex structure of the filler (irregular shape, particle size distribution) and a multi-component character of the binder, the applicability of these models varied with the powder-binder systems studied. However, the particular values of maximum loadings are in good accordance with the predictions based on powder characteristics. Simple modification of Frankel-Acrivos model to the systems containing unimodal hard-metal carbide powders with particles of an irregular shape and broad particle size distribution gave precise agreement between experimental data and model prediction. POLYM. COMPOS., 26:29,36, 2005. © 2004 Society of Plastics Engineers. [source] Working toward consensus: Providers' strategies to shift patients from curative to palliative treatment choicesRESEARCH IN NURSING & HEALTH, Issue 4 2001Sally A. Norton Abstract End-of-life decision making is a complex phenomenon and providers, patients, and families often have different views about the appropriateness of treatment choices. The results presented here are part of a larger grounded-theory study of reconciling decisions near the end of life. In particular, we examined how providers (N,=,15) worked near the end of patients' lives toward changing the treatment decisions of patients and families from those decisions that providers described as unrealistic (i.e., curative) to those that providers described as more realistic (i.e., palliative). According to providers, shifting patients' and families' choices from curative to palliative was usually accomplished by changing patients' and families' understanding of the patient's overall "big picture" to one that was consistent with the providers' understanding. Until patients and families shifted their understanding of the patient's condition,the big picture,they continued to make what providers judged as unrealistic treatment choices based on an inaccurate understanding of what was really going on. These unrealistic choices often precluded possibilities for a "good death." According to providers, the purpose of attempting to shift the patient or proxy's goals was that realistic goals lead to realistic palliative treatment choices that providers associated with a good death. In this article we review strategies used by providers when they believed a patient's death was imminent to attempt to shift patients' and families' understandings of the big picture, thus ultimately shifting their treatment decisions. © 2001 John Wiley & Sons, Inc. Res Nurs Health 24:258,269, 2001 [source] The RYR1 g.1843C>T mutation is associated with the effect of the IGF2 intron3-g.3072G>A mutation on muscle hypertrophyANIMAL GENETICS, Issue 1 2007A. Stinckens Summary Muscle growth is a complex phenomenon regulated by many factors, whereby net growth results from the combined action of synthesis and turnover. In pigs, two quantitative trait nucleotides (QTN) are known to have an important influence on muscle growth and fat deposition: one QTN is located in the ryanodine receptor 1 (RYR1) gene (RYR1 g.1843C>T) and the other, a paternally expressed QTN, is in the insulin-like growth factor 2 (IGF2) gene (IGF2 intron3-g.3072G>A). The mutation in IGF2 abrogates in vitro interaction with a repressor, which leads to a threefold increase of IGF2 expression in post-natal muscle. The family of the calpains, a family of Ca2+ -sensitive muscle endopeptidases, and their specific inhibitor calpastatin play an important role in post-natal protein degradation, also influencing muscle and carcass traits. This study investigated the possible interactions between the genotypes of the RYR1 and IGF2 QTN on IGF2 expression. Samples were taken from several muscles and from pigs at several ages, and messenger RNA expression levels were measured using a real-time quantification assay. IGF2 expression in m. longissimus dorsi of animals with mutations in both IGF2 and RYR1 was significantly lower than in animals that inherited the IGF2 mutation but were homozygous wildtype for RYR1. [source] Developing a global approach to the theory and practice of young people leaving state careCHILD & FAMILY SOCIAL WORK, Issue 3 2006John Pinkerton ABSTRACT This paper argues that globalization, although needing to be recognized as a highly complex phenomenon and a contested concept, should become part of the debate about improving the life chances of young people leaving care. Understanding globalization is essential to developing the effective strategies of engagement and resistance needed to address the social exclusion of these young people. Consideration is given to the considerable difficulties faced in moving from that general recognition to a sufficiently nuanced view of the impact of globalization on care leaving required as the basis for action. Existing approaches to promoting international exchange and understanding are discussed and a conceptual model presented as the means to start the work of identifying how the needs of care leavers are assessed and met in different national contexts. It is suggested that by identifying patterns of cross-national similarities and differences, it will become possible to understand and to engage with the processes and institutions of globalization. An international theoretical and practice agenda are proposed appropriate to the present early stage in ensuring that globalization works for and not against the interests of care leavers. [source] | |||||||||||||||||||||||||