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Interaction Terms (interaction + term)
Selected AbstractsBond Strength of Two Resin Cements on Dentin Using Different Cementation StrategiesJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 4 2010RENATA MARQUES MELO MS ABSTRACT Purpose:, This study evaluated the microtensile bond strength of two resin cements to dentin either with their corresponding self-etching adhesives or employing the three-step "etch-and-rinse" technique. The null hypothesis was that the "etch-and-rinse" adhesive system would generate higher bond strengths than the self-etching adhesives. Materials and Methods:, Thirty-two human molars were randomly divided into four groups (N = 32, n = 8/per group): G1) ED Primer self-etching adhesive + Panavia F; G2) All-Bond 2 "etch-and-rinse" adhesive + Panavia F; G3) Multilink primer A/B self-etching adhesive + Multilink resin cement; G4) All-Bond 2 + Multilink. After cementation of composite resin blocks (5 × 5 × 4 mm), the specimens were stored in water (37°C, 24 hours), and sectioned to obtain beams (±1 mm2 of adhesive area) to be submitted to microtensile test. The data were analyzed using 2-way analysis of variance and Tukey's test (, = 0.05). Results:, Although the cement type did not significantly affect the results (p = 0.35), a significant effect of the adhesive system (p = 0.0001) was found on the bond strength results. Interaction terms were not significant (p = 0.88751). The "etch-and-rinse" adhesive provided significantly higher bond strength values (MPa) with both resin cements (G2: 34.4 ± 10.6; G4: 33.0 ± 8.9) compared to the self-etching adhesive systems (G1: 19.8 ± 6.6; G3: 17.8 ± 7.2) (p < 0.0001). Pretest failures were more frequent in the groups where self-etching systems were used. Conclusion:, Although the cement type did not affect the results, there was a significant effect of changing the bonding strategy. The use of the three-step "etch-and-rinse" adhesive resulted in significantly higher bond strength for both resin cements on dentin. CLINICAL SIGNIFICANCE Dual polymerized resin cements tested could deliver higher bond strength to dentin in combination with "etch-and-rinse" adhesive systems as opposed to their use in combination with self-etching adhesives. (J Esthet Restor Dent 22:262,269, 2010) [source] Employment and quality of life in liver transplant recipientsLIVER TRANSPLANTATION, Issue 9 2007Sammy Saab The purposes of liver transplantation (LT) include the extension of survival, improvement in quality of life, and the return of the recipient as a contributing member of society. Employment is one measure of the ability to return to society. The aim of this study is to determine the factors affecting employment/subemployment after LT. A total of 308 adult liver transplant recipients who were seen at the University of California, Los Angeles were administered the Medical Outcomes Short Form 36 (SF-36) and a questionnaire regarding work history and insurance coverage. Multivariate analysis were used to identify independent variables associated with posttransplantation employment. Interaction terms were used to examine effect modification. Of 308 transplant recipients, 218 (70.8%) worked prior to transplantation, and 78 (27%) worked posttransplantation. Pretransplant variables that were independently associated with posttransplantation employment included the following: lack of disability income (odds ratio [OR] = 1.86; 95% confidence interval [CI], 1.32-7.18; P = 0.36); health maintenance organization (HMO)/preferred provider organization (PPO) insurance (OR = 3.08; 95% CI, 1.32-7.18; P < 0.01); the number of hours worked (OR = 1.17; 95% CI, 1.08-1.28; P < 0.01); and the lack of diabetes mellitus (OR = 0.23; 95% CI, 0.70-0.73; P < 0.01). An interaction term between disability income and hours worked prior to transplantation (OR = 0.16; 95 % CI, 0.03-0.83; P = 0.03) was independently associated with posttransplantation employment. In a separate regression model of SF-36 responses, posttransplantation physical functioning (OR = 1.17; 95% CI, 1.10-1.26; P < 0.01) and role-physical (OR = 1.1; 95% CI, 1.02-1.16; P < 0.01) were independently associated with employment after transplantation. In conclusion, HMO or PPO insurance, lack of disability income coverage prior to transplant, the absence of diabetes mellitus, the number of hours worked prior to transplantation, and high physical functioning were associated with posttransplantation employment. Liver Transpl 13:1330,1338, 2007. © 2007 AASLD. [source] Variable carbon recovery of Walkley-Black analysis and implications for national soil organic carbon accountingEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2007S. Lettens Summary There is considerable interest in the computation of national and regional soil carbon stocks, largely as the result of the provisions of the Kyoto Protocol. Such stocks are often calculated and compared without proper reference to the uncertainties induced by different analytical methodologies. We illustrate the nature and magnitude of these uncertainties with the present soil organic carbon (SOC) study in Belgium. The SOC recovery of the Walkley-Black method was investigated based on a database of 475 samples of silt loam and sandy soils, which cover different soil depths and vegetation types in northern Belgium. The organic carbon content of the soil samples was measured by the original Walkley-Black method and by a total organic carbon analyser. The recovery was computed as the ratio of these two results per soil sample. Land use, texture and soil sampling depth had a significant influence on the recovery as well as their three-way interaction term (land use × texture × sampling depth). The impact of a land use, texture and sampling depth dependent Walkley-Black correction on the year 2000 SOC inventory of Belgium was determined by regression analysis. Based on new correction factors, the national SOC stocks increased by 22% for the whole country, ranging from 18% for cropland to 31% for mixed forest relative to the standard corrected SOC inventory. The new recovery values influenced therefore not only C stocks in the year 2000, but also the expected SOC change following land use change. Adequate correction of Walkley-Black measurements is therefore crucial for the absolute and comparative SOC assessments that are required for Kyoto reporting and must be computed to take into account the regional status of soil and land use. ,Universal' corrections are probably an unrealistic expectation. [source] Trends in aquatic macrophyte species turnover in Northern Ireland , which factors determine the spatial distribution of local species turnover?GLOBAL ECOLOGY, Issue 5 2004Einar Heegaard ABSTRACT Aim, The study examined qualitative predictions of ecological theories in relation to the spatial distribution of species turnover of aquatic macrophytes, through the following parameters: (1) distance between lakes (2) chemical conditions of the lakes (3) chemical differences between the lakes, and (4) the lake size. Location, 562 lakes dispersed throughout Northern Ireland were analysed. Methods, To obtain species turnover estimates independent of richness, the average distance between focal lakes and their five nearest neighbours in ordination space (DCA) was standardized by the species richness in a Generalized Additive Model (GAM). The relationships between species turnover and ecological (chemical condition, chemical difference, distance between lakes, and lake-size) and geographical parameters (latitude, longitude, and altitude) were analysed using GAM. Results, The results indicate that the pattern in species turnover is a combination of the chemical conditions and the distance between the lakes, including the interaction term. The effects of chemical heterogeneity and lake size parameters were both positive but weak. In general, increased distance and decreased ionic concentration contribute to increased turnover. The influence of distance on species turnover is strongest at low and high altitude, and at mid-elevation the species turnover is mainly driven by the chemical conditions. Towards the north there is an increasing influence of distance, whereas in the south the chemical conditions have their strongest influence. Conclusions, There is a need for components from several established ecological theories to explain the spatial trends in species turnover within Northern Ireland. Central theories in this particular study are the population/metapopulation dynamics, the continuum concept, and the species-pool concept. [source] The Impact of Welfare Reform on Insurance Coverage before Pregnancy and the Timing of Prenatal Care InitiationHEALTH SERVICES RESEARCH, Issue 4 2007Norma I. Gavin Objective. This study investigates the impact of welfare reform on insurance coverage before pregnancy and on first-trimester initiation of prenatal care (PNC) among pregnant women eligible for Medicaid under welfare-related eligibility criteria. Data Sources. We used pooled data from the Pregnancy Risk Assessment Monitoring System for eight states (AL, FL, ME, NY, OK, SC, WA, and WV) from 1996 through 1999. Study Design. We estimated a two-part logistic model of insurance coverage before pregnancy and first-trimester PNC initiation. The impact of welfare reform on insurance coverage before pregnancy was measured by marginal effects computed from coefficients of an interaction term for the postreform period and welfare-related eligibility and on PNC initiation by the same interaction term and the coefficients of insurance coverage adjusted for potential simultaneous equation bias. We compared the estimates from this model with results from simple logistic, ordinary least squares, and two-stage least squares models. Principal Findings. Welfare reform had a significant negative impact on Medicaid coverage before pregnancy among welfare-related Medicaid eligibles. This drop resulted in a small decline in their first-trimester PNC initiation. Enrollment in Medicaid before pregnancy was independent of the decision to initiate PNC, and estimates of the effect of a reduction in Medicaid coverage before pregnancy on PNC initiation were consistent over the single- and two-stage models. Effects of private coverage were mixed. Welfare reform had no impact on first-trimester PNC beyond that from reduced Medicaid coverage in the pooled regression but separate state-specific regressions suggest additional effects from time and income constraints induced by welfare reform may have occurred in some states. Conclusions. Welfare reform had significant adverse effects on insurance coverage and first-trimester PNC initiation among our nation's poorest women of childbearing age. Improved outreach and insurance options for these women are needed to meet national health goals. [source] Initial evidence on whether use of professional fundraising services increases fundraising effectivenessINTERNATIONAL JOURNAL OF NONPROFIT & VOLUNTARY SECTOR MARKETING, Issue 1 2010Nicholas P. Marudas We provide initial evidence on whether use of professional fundraising services by US nonprofit organizations (NPOs) increases the effectiveness of NPOs' fundraising efforts. To a well-tested model of organization-level donations, we add an interaction term that captures the impact that professional fundraising fees an NPO incurs has on the effectiveness of an NPOs' spending on fundraising in raising donations. We find that professional fundraising fees has a significant positive impact on the effectiveness of fundraising efforts in raising donations for NPOs in the full, education, and health samples, but no impact for NPOs in the arts and human services samples. For NPOs in the full sample and NPOs in the education sample, one quarter of the effect of fundraising on donations stems from the positive impact of professional fundraising services on the effectiveness of fundraising in raising donations. For NPOs in the health sample, one half of the effect of fundraising on donations stems from the positive impact of professional fundraising services on the effectiveness of fundraising in raising donations. These results suggest that professional fundraising services significantly enhance the effectiveness of fundraising for these types of NPOs. While the results of this study seem to confirm the decisions of managers of education and health NPOs to utilize professional fundraising services, the results also suggest that managers of arts and human services NPOs may want to reconsider using professional fundraising services, at least the types of services they currently purchase and the way they currently utilize such services. Copyright © 2009 John Wiley & Sons, Ltd. [source] Cognitive Status, Muscle Strength, and Subsequent Disability in Older Mexican AmericansJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 9 2005Mukaila A. Raji MD Objectives: To examine the association between Mini-Mental State Examination (MMSE) score and subsequent muscle strength (measured using handgrip strength) and to test the hypothesis that muscle strength will mediate any association between impaired cognition and incident activity of daily living (ADL) disability over a 7-year period in elderly Mexican Americans who were initially not disabled. Design: A 7-year prospective cohort study (1993,2001). Setting: Five southwestern states (Texas, New Mexico, Colorado, Arizona, and California). Participants: Two thousand three hundred eighty-one noninstitutionalized Mexican-American men and women aged 65 and older with no ADL disability at baseline. Measurements: In-home interviews in 1993/1994, 1995/1996, 1998/1999, and 2000/2001 assessed social and demographic factors, medical conditions (diabetes mellitus, stroke, heart attack, and arthritis), body mass index (BMI), depressive symptomatology, handgrip muscle strength, and ADLs. MMSE score was dichotomized as less than 21 for poor cognition and 21 or greater for good cognition. Main outcomes measures were mean and slope of handgrip muscle strength over the 7-year period and incident disability, defined as new onset of any ADL limitation at the 2-, 5-, or 7-year follow-up interview periods. Results: In mixed model analyses, there was a significant cross-sectional association between having poor cognition (MMSE<21) and lower handgrip strength, independent of age, sex, and time of interview (estimate=,1.41, standard error (SE)=0.18; P<.001). With the introduction of a cognition-by-time interaction term into the model, there was also a longitudinal association between poor cognition and change in handgrip strength over time (estimate=,0.25, SE=0.06; P<.001), indicating that subjects with poor cognition had a significantly greater decline in handgrip strength over 7 years than those with good cognition, independent of age, sex, and time. This longitudinal association between poor cognition and greater muscle decline remained significant (P<.001) after controlling for age, sex, education, and time-dependent variables of depression, BMI, and medical conditions. In general estimation equation models, having poor cognition was associated with greater risk of 7-year incident ADL disability (odds ratio=2.01, 95% confidence interval (CI)=1.60,2.52); the magnitude of the association decreased to 1.66 (95% CI=1.31,2.10) when adjustment was made for handgrip strength. Conclusion: Older Mexican Americans with poor cognition had steeper decline in handgrip muscle strength over 7 years than those with good cognition, independent of other demographic and health factors. A possible mediating effect of muscle strength on the association between poor cognition and subsequent ADL disability was also indicated. [source] Patterns of woody plant species richness in the Iberian Peninsula: environmental range and spatial scaleJOURNAL OF BIOGEOGRAPHY, Issue 10 2008Ole R. Vetaas Abstract Aim, Climate-based models often explain most of the variation in species richness along broad-scale geographical gradients. We aim to: (1) test predictions of woody plant species richness on a regional spatial extent deduced from macro-scale models based on water,energy dynamics; (2) test if the length of the climate gradients will determine whether the relationship with woody species richness is monotonic or unimodal; and (3) evaluate the explanatory power of a previously proposed ,water,energy' model and regional models at two grain sizes. Location, The Iberian Peninsula. Methods, We estimated woody plant species richness on grid maps with c. 2500 and 22,500 km2 cell size, using geocoded data for the individual species. Generalized additive models were used to explore the relationships between richness and climatic, topographical and substrate variables. Ordinary least squares regression was used to compare regional and more general water,energy models in relation to grain size. Variation partitioning by partial regression was applied to find how much of the variation in richness was related to spatial variables, explanatory variables and the overlap between these two. Results, Water,energy dynamics generate important underlying gradients that determine the woody species richness even over a short spatial extent. The relationships between richness and the energy variables were linear to curvilinear, whereas those with precipitation were nonlinear and non-monotonic. Only a small fraction of the spatially structured variation in woody species richness cannot be accounted for by the fitted variables related to climate, substrate and topography. The regional models accounted for higher variation in species richness than the water,energy models, although the water,energy model including topography performed well at the larger grain size. Elevation range was the most important predictor at all scales, probably because it corrects for ,climatic error' due to the unrealistic assumption that mean climate values are evenly distributed in the large grid cells. Minimum monthly potential evapotranspiration was the best climatic predictor at the larger grain size, but actual evapotranspiration was best at the smaller grain size. Energy variables were more important than precipitation individually. Precipitation was not a significant variable at the larger grain size when examined on its own, but was highly significant when an interaction term between itself and substrate was included in the model. Main conclusions, The significance of range in elevation is probably because it corresponds to several aspects that may influence species diversity, such as climatic variability within grid cells, enhanced surface area, and location for refugia. The relative explanatory power of energy and water variables was high, and was influenced by the length of the climate gradient, substrate and grain size of the analysis. Energy appeared to have more influence than precipitation, but water availability is also determined by energy, substrate and topographic relief. [source] Should we use proportional sampling for species,area studies?JOURNAL OF BIOGEOGRAPHY, Issue 8 2004José H. Schoereder Abstract Aim, In this paper we aim to show that proportional sampling can detect species,area relationships (SARs) more effectively than uniform sampling. We tested the contribution of alpha and beta diversity in ant communities as explanations for the SAR. Location, Tropical forest remnants in Viçosa, Minas Gerais, Brazil (20 °45, S, 42 °50, W). Methods, We sampled 17 forest remnants with proportional sampling. To disentangle sampling effects from other mechanisms, species richness was fitted in a model with remnant size, number of samples (sampling effects) and an interaction term. Results, A SAR was observed independent of the number of samples, discarding sampling effects. Alpha diversity was not influenced by remnant size, and beta diversity increased with remnant size; evidence to the fact that habitat diversity within remnants could be the dominant cause of the SAR. Such a relationship between beta diversity and remnant area may have also arisen due to the combined effects of territoriality and aggregation of ant species. Main conclusions, The proposed model, together with proportional sampling, allowed the distinction between sampling effects and other mechanisms. [source] Who benefits from learning with 3D models? the case of spatial abilityJOURNAL OF COMPUTER ASSISTED LEARNING, Issue 6 2006T. Huk Abstract Empirical studies that focus on the impact of three-dimensional (3D) visualizations on learning are to date rare and inconsistent. According to the ability-as-enhancer hypothesis, high spatial ability learners should benefit particularly as they have enough cognitive capacity left for mental model construction. In contrast, the ability-as-compensator hypothesis proposes that low spatial ability learners should gain particular benefit from explicit graphical representations as they have difficulty mentally constructing their own visualizations. This study examines the impact that interactive 3D models implemented within a hypermedia-learning environment have on understanding of cell biology. Test scores in a subsequent knowledge acquisition test demonstrated a significant interaction term between students' spatial ability and presence/absence of 3D models. Only students with high spatial ability benefited from the presence of 3D models, while low spatial ability students got fewer points when learning this way. When using 3D models, high spatial ability students perceived their cognitive load to be low whereas the opposite was true for low spatial ability students. The data suggest that students with low spatial ability became cognitively overloaded by the presence of 3D models, while high spatial ability students benefited from them as their total cognitive load remained within working memory limits. [source] Antifungal Activity Stability of Flaxseed Protein Extract Using Response Surface MethodologyJOURNAL OF FOOD SCIENCE, Issue 1 2008Y. Xu ABSTRACT:, The stability of the antifungal activity of flaxseed (Linum usitatissimum) protein extract was evaluated in this study. Response surface methodology (RSM) using Box,Behnken factorial design was used to evaluate the effects of treatment variables, that is, temperature (50 to 90 °C), time (1 to 29 min), and pH (2 to 8), on the residual antifungal activity (RAA) against Penicillium chrysogenum, Fusarium graminearum, Aspergillus flavus, and a Penicillium sp. isolated from moldy noodles. Regression analyses suggested that the linear terms of the temperature and time had significant (P < 0.05) negative effects on the RAA against all test fungi, whereas that of pH had a significant (P < 0.1) positive role on the RAA of all 3 fungi. In addition, the RAA was significantly (P < 0.05) affected by the quadratic terms of time for all fungi, and the quadratic term of temperature played a significant (P < 0.1) role on RAA against F. graminearum. One interaction term (temperature-pH) was found to significantly (P < 0.1) affect the RAA against both Penicillium strains tested. The results indicated that , 90% antifungal activity was lost after the protein extracts were heated at 90 °C for 8 min except for F. graminearum. At pasteurization condition, , 50% activity was retained except for P. chrysogenum. The results also suggested that neutral and alkaline pH favored the antifungal activity stability of the protein extracts. Thus, flaxseed protein might be promising if used as a preservative in foods with neutral or alkaline pH requiring mild heat treatments. [source] Nonmarital Fertility and the Effects of Divorce Rates on Youth Suicide RatesJOURNAL OF MARRIAGE AND FAMILY, Issue 4 2006Steven F. Messner Using pooled, time-series data for a sample of 15 developed nations, we assess the effect of divorce rates on gender-specific suicide rates for youths aged 15 , 19 with models of relative cohort size, lagged nonmarital fertility, and an interaction term for divorce rates and nonmarital fertility. The results reveal that, for young men, relative cohort size is positively related to suicide rates, and divorce rates interact with lagged nonmarital fertility. The interaction effect indicates that increases in divorces are especially consequential for suicide cohorts of male youths who were born in periods of high nonmarital fertility. For female youths, only divorce rates exert a significant effect on suicide rates, and it is a positive, main effect. [source] Occupational stress in (inter)action: the interplay between job demands and job resourcesJOURNAL OF ORGANIZATIONAL BEHAVIOR, Issue 5 2005Natasja van Vegchel The present study addresses theoretical issues involving different interaction effects between job demands and job resources, accompanied by a thorough empirical test of interaction terms in the demand,control (DC) model and the effort,reward imbalance (ERI) model in relation to employee health and well-being (i.e., exhaustion, psychosomatic health complaints, company-registered sickness absence). Neither the DC model nor the ERI model gives a clear theoretical rationale or preference for a particular interaction term. Hierarchical regression analyses were conducted among 405 nursing home employees and cross-validated in a comparable sample (N,=,471). Results including cross-validation showed that only a multiplicative interaction term yielded consistent results for both the DC model and the ERI model. Theoretical as well as empirical results argue for a multiplicative interaction term to test the DC model and the ERI model. Future job stress research may benefit from the idea that there should be a theoretical preference for any interaction form, either in the DC model or in the ERI model. However, more research on interactions is needed to address this topic adequately. Copyright © 2005 John Wiley & Sons, Ltd. [source] Employment and quality of life in liver transplant recipientsLIVER TRANSPLANTATION, Issue 9 2007Sammy Saab The purposes of liver transplantation (LT) include the extension of survival, improvement in quality of life, and the return of the recipient as a contributing member of society. Employment is one measure of the ability to return to society. The aim of this study is to determine the factors affecting employment/subemployment after LT. A total of 308 adult liver transplant recipients who were seen at the University of California, Los Angeles were administered the Medical Outcomes Short Form 36 (SF-36) and a questionnaire regarding work history and insurance coverage. Multivariate analysis were used to identify independent variables associated with posttransplantation employment. Interaction terms were used to examine effect modification. Of 308 transplant recipients, 218 (70.8%) worked prior to transplantation, and 78 (27%) worked posttransplantation. Pretransplant variables that were independently associated with posttransplantation employment included the following: lack of disability income (odds ratio [OR] = 1.86; 95% confidence interval [CI], 1.32-7.18; P = 0.36); health maintenance organization (HMO)/preferred provider organization (PPO) insurance (OR = 3.08; 95% CI, 1.32-7.18; P < 0.01); the number of hours worked (OR = 1.17; 95% CI, 1.08-1.28; P < 0.01); and the lack of diabetes mellitus (OR = 0.23; 95% CI, 0.70-0.73; P < 0.01). An interaction term between disability income and hours worked prior to transplantation (OR = 0.16; 95 % CI, 0.03-0.83; P = 0.03) was independently associated with posttransplantation employment. In a separate regression model of SF-36 responses, posttransplantation physical functioning (OR = 1.17; 95% CI, 1.10-1.26; P < 0.01) and role-physical (OR = 1.1; 95% CI, 1.02-1.16; P < 0.01) were independently associated with employment after transplantation. In conclusion, HMO or PPO insurance, lack of disability income coverage prior to transplant, the absence of diabetes mellitus, the number of hours worked prior to transplantation, and high physical functioning were associated with posttransplantation employment. Liver Transpl 13:1330,1338, 2007. © 2007 AASLD. [source] Noninvasive assessment of energy expenditure in childrenAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2006Isabelle Sarton-Miller This study establishes an affordable, simple, and noninvasive method to assess energy expenditure (EE) in children, an underrepresented group. The method is based on regression modeling, where prediction of oxygen consumption (VO2), a proxy of EE, was deduced from heart rate (HR) and several variables that adjusted for interindividual variability. Limb activities (arms vs. legs) and posture (sitting vs. standing) were represented in the regression as dichotomous covariates. The order of activities and intensities was randomized. Seventy-four children (aged 7,10 years), raised at sea-level (Seattle, WA), comprised the sample. Anthropometric measures were taken, and VO2 and HR were measured for activities using the arms in sitting and standing positions (mixing and punching), as well as walking at different velocities on a treadmill. Repeated measures and least square regression estimation were used. HR, body mass, number of hours of physical activity per week (HPA), an interaction term between sitting and standing resting HR, and the two dichotomous variables, sex and limbs, were significant covariates; posture was not. Several equations were developed for various field uses. The equations were built from sea-level data, but ultimately this method could serve as a baseline for developing a similar approach in other populations, where noninvasive estimation of EE is imperative in order to gain a better understanding of children's energetic issues. Am. J. Hum. Biol. 18:600,609, 2006. © 2006 Wiley-Liss, Inc. [source] Genotype and temperature influence pea aphid resistance to a fungal entomopathogenPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2003David A. Stacey Abstract. The influence of temperature on life history traits of four Acyrthosiphon pisum clones was investigated, together with their resistance to one genotype of the fungal entomopathogen Erynia neoaphidis. There was no difference among aphid clones in development rate, but they did differ in fecundity. Both development rate and fecundity were influenced by temperature, but all clones showed similar responses to the changes in temperature (i.e. the interaction term was nonsignificant). However, there were significant differences among clones in susceptibility to the pathogen, and this was influenced by temperature. Furthermore, the clones differed in how temperature influenced susceptibility, with susceptibility rankings changing with temperature. Two clones showed changes in susceptibility which mirrored changes in the in vitro vegetative growth rate of E. neoaphidis at different temperatures, whereas two other clones differed considerably from this expected response. Such interactions between genotype and temperature may help maintain heritable variation in aphid susceptibility to fungal pathogen attack and have implications for our understanding of disease dynamics in natural populations. This study also highlights the difficulties of drawing conclusions about the efficacy of a biological control agent when only a restricted range of pest genotypes or environmental conditions are considered. [source] Baseline 6-Min Walk Distance Predicts Survival in Lung Transplant CandidatesAMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2008T. Martinu In a large, prospectively followed, two-center cohort of patients listed for lung transplantation (n = 376), we used Cox proportional hazards models to determine the importance of baseline 6-min walk distance (6MWD) in predicting patient survival. 6MWD used as a continuous variable was a significant predictor of survival after adjusting for other important covariates when transplant was considered as a time-varying covariate (HR for each 500 ft increase in 6MWD = 0.57, 95% CI: 0.43,0.77, p = 0.0002). 6MWD remained an important predictor of survival in models that considered only survival to transplant (HR for each 500 ft increase in 6MWD = 0.41, 95% CI: 0.27,0.62, p < 0.0001) or survival only after transplant (HR for each 500 ft increase in 6MWD = 0.40, 95% CI: 0.22,0.72, p = 0.002). Unadjusted Kaplan-Meier analysis demonstrates significantly different survival by 6MWD tertiles (<900, 900,1200, or >1200 ft, p-value = 0.0001). In the overall model, 6MWD prediction of survival was relatively homogeneous across disease category (6MWD by disease interaction term, p-value = 0.63). Our results demonstrate a significant relationship between baseline 6MWD and survival among patients listed for lung transplantation that exists across all native disease categories and extends through transplantation. The 6MWD is thus a useful measure of both urgency and utility among patients awaiting lung transplantation. [source] Structure solution of the basic decagonal Al,Co,Ni phase by the atomic surfaces modelling methodACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2002Antonio Cervellino The atomic surfaces modelling technique has been used to solve the structure of the basic Ni-rich Al,Co,Ni decagonal phase. Formula Al70.6Co6.7Ni22.7, space group , five-dimensional unit-cell parameters: d1 = d4 = 4.752,(3),Å, d2 = d3 = 3.360,(2),Å, d5 = 8.1710,(2),Å; ,12 = ,34 = 69.295°, ,13 = ,24 = 45°, ,14 = 41.410°, ,23 = ,i5 = 90° (i = 1,4), V = 291.2,(7),Å5; Dx = 3.887,Mg,m,3. Refinement based on |F|; 2767 unique reflections (|F| > 0), 749 parameters, R = 0.17, wR = 0.06. Describing the structure of quasicrystals embedded in n -dimensional superspace in principle takes advantage of n -dimensional periodicity to select the minimal set of degrees of freedom for the structure. The method of modelling of the atomic surfaces yielded the first fully detailed structure solution of this phase. Comparison with numerous former, less accurate models confirms several features already derived, but adds a new essential insight of the structure and its complexity. The atoms fill the space forming recurrent structure motifs, which we will (generically) refer to as clusters. However, no unique cluster exists, although differences are small. Each cluster shows a high degree of structural disorder. This gives rise to a large configurational entropy, as much as expected in a phase which is stable at high temperature. On the other side, the cluster spatial arrangement is perfectly quasiperiodic. These considerations, corroborated by analysis of the structural relationship with neighbouring periodic phases, strongly suggest the existence of a non-local, long-range interaction term in the total energy which may be essential to the stability. [source] The effect of the CYP1A2 *1F mutation on CYP1A2 inducibility in pregnant womenBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 5 2002Anna Nordmark Aims, To investigate the influence of the CYP1A2*1F mutation on CYP1A2 activity in smoking and nonsmoking pregnant women. Methods Pregnant women (n = 904) who served as control subjects in a case-control study of early fetal loss were investigated. They were phenotyped for CYP1A2 using dietary caffeine and the urinary ratio AFMU + 1X + 1 U/1,7 U. An assay for CYP1A2*1F using 5,-nuclease assay (Taqman) was developed to genotype the population. Results, The frequencies of *1 A and *1F alleles among Swedish women were 0.29 and 0.71, respectively. There was no statistically significant difference in CYP1A2 activity between the genotypes, although a trend towards enhanced activity was observed in *1F/*1F (log MRc 0.77) and *1F/*1 A (log MRc 0.82) genotypes compared with the *1 A/*1 A genotype (log MRc 0.71) (anovaP = 0.07). The mean difference between the *1 A homozygotes and the heterozygotes was 0.11 [95% confidence interval of the difference: (,0.21, ,0.01)] and that between the *1 A and *1F homozygotes was 0.05 [95% confidence interval of the difference: (,0.13, 0.03)]. No significant effect (P = 0.22) of the *1F on CYP1A2 activity was observed in smokers, tested using an interaction term (smoking * genotype) in the anova model (*1F/*1F log MRc 0.79, *1F/*1 A log MRc 0.86, and *1 A/*1 A log MRc 0.73). In smokers, there was no difference in ratio between homozygotes for the *1 A and *1F alleles [mean difference ,0.06; 95% confidence interval of the difference: ,0.22, 0.11] or between *1 A/*1 A and *1 A/*1F genotypes [mean difference ,0.13; 95% confidence interval of the difference: ,0.29, 0.04]. Conclusions, The effect of the CYP1A2*1F mutation on CYP1A2 activity in smoking pregnant women could not be confirmed. [source] Race modifies the association between breast carcinoma pathologic prognostic indicators and the positive status for HER-2/neuCANCER, Issue 10 2005Azadeh T. Stark Ph.D. Abstract BACKGROUND Inferences about the variations in the biology of breast carcinoma between African-Americans and Caucasians have been reported. The difference in the prevalence of positive HER-2/neu breast carcinoma was evaluated and the race-specific risk was assessed for positive HER-2/neu among a cohort of women diagnosed with their first primary breast carcinoma, given the accepted prognostic pathologic indicators for positive HER-2/neu status. METHODS Demographic, clinical, and pathologic data were collected from existing databases. The status of HER-2/neu was considered positive if the immunohistochemistry score was 3+ or if the fluorescent in situ hybridization indicated a ratio greater than 2. Multivariable logistic regression was used to determine the race-specific risk for HER-2/neu positive breast carcinoma. RESULTS The difference in the prevalence of HER-2/neu -positive status between African-American and Caucasian women was not statistically significant (P = 0.46). For Caucasian women the likelihood for positive HER-2/neu was statistically significant and increased almost linearly within each stage with nuclear grade dedifferentiation relative to the reference group, women with Stage 1, Grade 1 carcinomas. For African-American women, this risk was not significantly associated with stage, nuclear grade, their interaction term, or other pathologic prognostic indicators. CONCLUSIONS The findings suggest that race modifies the association between the pathologic prognostic indicators of breast carcinoma and the likelihood of HER-2/neu -positive carcinoma. So far, clinical correlative studies of HER-2/neu have not included race as an independent variable. Concerns about the limited generalizability and the need for validation of the findings across racial lines have been expressed previously. Cancer 2005. © 2005 American Cancer Society. [source] The transferability of distribution models across regions: an amphibian case studyDIVERSITY AND DISTRIBUTIONS, Issue 3 2009Flavio Zanini ABSTRACT Aim, Predicting species distribution is of fundamental importance for ecology and conservation. However, distribution models are usually established for only one region and it is unknown whether they can be transferred to other geographical regions. We studied the distribution of six amphibian species in five regions to address the question of whether the effect of landscape variables varied among regions. We analysed the effect of 10 variables extracted in six concentric buffers (from 100 m to 3 km) describing landscape composition around breeding ponds at different spatial scales. We used data on the occurrence of amphibian species in a total of 655 breeding ponds. We accounted for proximity to neighbouring populations by including a connectivity index to our models. We used logistic regression and information-theoretic model selection to evaluate candidate models for each species. Location, Switzerland. Results, The explained deviance of each species' best models varied between 5% and 32%. Models that included interactions between a region and a landscape variable were always included in the most parsimonious models. For all species, models including region-by-landscape interactions had similar support (Akaike weights) as models that did not include interaction terms. The spatial scale at which landscape variables affected species distribution varied from 100 m to 1000 m, which was in agreement with several recent studies suggesting that land use far away from the ponds can affect pond occupancy. Main conclusions, Different species are affected by different landscape variables at different spatial scales and these effects may vary geographically, resulting in a generally low transferability of distribution models across regions. We also found that connectivity seems generally more important than landscape variables. This suggests that metapopulation processes may play a more important role in species distribution than habitat characteristics. [source] Early intervention with second-generation antipsychotics in first-episode psychosis: results of an 8-week naturalistic studyEARLY INTERVENTION IN PSYCHIATRY, Issue 1 2010Richard C. Josiassen Abstract Objective: The objective was to compare short-term effectiveness of aripiprazole with three other second-generation antipsychotics (SGAs) in the treatment of first-episode psychosis. Method: In a naturalistic, ,single-blind' design, 60 subjects experiencing their first psychotic episode were treated for 8 weeks with aripiprazole (n = 19), risperidone (n = 16), olanzapine (n = 14) or quetiapine (n = 11). Medication and dosing decisions were made by treating psychiatrists, constrained to once-a-day dosing, low initial doses and no clozapine. Weekly ratings were obtained using the Positive and Negative Syndrome Scale (PANSS), Simpson-Angus Rating Scale and Barnes Akathasia Rating Scale. Weight and vital signs were also collected weekly. Results: The group presented with severe psychotic symptoms (mean baseline PANSS total score of 105.2), which were reduced rapidly (P < 0.0005). The between-group and group by time interaction terms were non-significant. Similar reductions were seen across all PANSS sub-scales. At Week 1 the mean PANSS Activation Scale score was reduced more with olanzapine than in the other groups (P < 0.002). Few instances of extrapyramidal symptoms occurred; all were sporadic and did not require treatment. Group body weight increased by 7.3% over the study. Vital signs remained unchanged. Conclusions: Early intervention with low doses of four SGAs led to rapid symptom reduction in first-episode psychotic patients with severe psychopathology. Although no clear medication advantages were observed in the short term, longer duration studies with larger samples will be required for determining efficacy, rates of compliance, relapse prevention and diminished incidence of extrapyramidal signs and symptoms. [source] A comparison of the effectiveness of group-based and pharmacy-led smoking cessation treatment in GlasgowADDICTION, Issue 2 2009Linda Bauld ABSTRACT Aim To compare the characteristics and outcomes of users accessing pharmacy and group-based smoking treatment. Design Observational study of administrative information linked with survey data. Setting Glasgow, Scotland. Participants A total of 1785 service users who set a quit date between March and May 2007. Intervention Smoking treatment services based in pharmacies providing one-to-one support, and in the community offering group support. Measurements Routine monitoring data included information about basic demographic characteristics, deprivation category of residence, nature of intervention and smoking status at 4-week follow-up determined by carbon monoxide (CO) readings ,10. These data were supplemented by information about socio-economic status and smoking-related behaviours obtained from consenting service recipients by treatment advisers. Findings In the pharmacy-based service 18.6 % of users (n = 1374) were CO-validated as a quitter at 4 weeks, compared with 35.5 % (n = 411) in the group-based service. In a multivariate model, restricted to participants (n = 1366) with data allowing adjustment for socio-demographic and behavioural characteristics and including interaction terms, users who accessed the group-based services were almost twice as likely (odds ratio 1.980; confidence interval 1.50,2.62) as those who used pharmacy-based support to have quit smoking at 4-week follow-up. Conclusions Specialist-led group-based services appear to have higher quit rates than one-to-one services provided by pharmacies but the pharmacy services treat many more smokers. More research is needed to determine what can be done to bring the success rates of pharmacy services up to those of specialist-led groups and how to expand access to group-based services. [source] Personality, gender, and cryingEUROPEAN JOURNAL OF PERSONALITY, Issue 1 2001Mathell Peter This study examined gender differences in crying as well as associations between basic personality traits and self-reported indices of crying. Forty-eight men and 56 women completed the Five-Factor Personality Inventory and the Adult Crying Inventory. Substantial gender differences were demonstrated in crying frequency and crying proneness, but not with respect to mood changes after crying. As predicted, women reported a higher frequency of crying and more proneness to cry both for negative and positive reasons. For women, all these crying indices were negatively associated with Emotional Stability. For men, only a significant negative relationship between Emotional Stability and crying for negative reasons emerged. No clear links were found between personality and mood changes after crying. Multiple regression analysis revealed a significant predictive role of gender for crying proneness, even when controlling for personality differences, but not for crying frequency. Adding personality by gender interaction terms resulted in a disappearance of the main effect of sex, while significant interactions with personality factors showed up for crying frequency and general crying proneness. It is suggested that future research on the relationship between personality and crying should focus more on the underlying mechanisms of observed relationships. Furthermore, it is recommended that future research should examine the role of different emotion regulation strategies. In addition, biological factors, temperament, upbringing measures, and socio-demographic variables should be taken into account. Copyright © 2001 John Wiley & Sons, Ltd. [source] An ultraviolet-finite Hamiltonian approach on the noncommutative Minkowski spaceFORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 6-7 2004D. Bahns This is an exposition of joint work with S. Doplicher, K. Fredenhagen, and G. Piacitelli on field theory on the noncommutative Minkowski space [1]. The limit of coinciding points is modified compared to ordinary field theory in a suitable way which allows for the definition of so-called regularized field monomials as interaction terms. Employing these in the Hamiltonian formalism results in an ultraviolet finite S -matrix. [source] Effects of hydrogeomorphic region, catchment storage and mature forest on baseflow and snowmelt stream water quality in second-order Lake Superior Basin tributariesFRESHWATER BIOLOGY, Issue 5 2003Naomi E. Detenbeck SUMMARY 1. In this study we predict stream sensitivity to non-point source pollution based on the non-linear responses of hydrological regimes and associated loadings of non-point source pollutants to catchment properties. We assessed two hydrologically based thresholds of impairment, one for catchment storage (5,10%) and one for mature forest (<50% versus >60% of catchment in mature forest cover) across two different hydrogeomorphic regions within the Northern Lakes and Forest (NLF) ecoregion: the North Shore [predominantly within the North Shore Highlands Ecological Unit] and the South Shore (predominantly within the Lake Superior Clay Plain Ecological Unit). Water quality samples were collected and analysed during peak snowmelt and baseflow conditions from 24 second-order streams grouped as follows: three in each region × catchment storage × mature forest class. 2. Water quality was affected by a combination of regional influences, catchment storage and mature forest. Regional differences were significant for suspended solids, phosphorus, nitrogen: phosphorus ratios, dissolved organic carbon (DOC) and alkalinity. Catchment storage was significantly correlated with dissolved silica during the early to mid-growing season, and with DOC, specific conductance and alkalinity during all seasons. Total nitrogen and dissolved nitrogen were consistently less in low mature forest than in high mature forest catchments. Catchment storage interacted with the influence of mature forest for only two metrics: colour and the soluble inorganic nitrogen : phosphorus ratio. 3. Significant interaction terms (region by mature forest or region by storage) suggest differences in regional sensitivity for conductance, alkalinity, total organic carbon, and colour, as well as possible shifts in thresholds of impact across region or mature forest class. 4. Use of the NLF Ecoregion alone as a basis for setting regional water quality criteria would lead to the misinterpretation of reference condition and assessment of condition. There were pronounced differences in background water quality between the North and South Shore streams, particularly for parameters related to differences in soil parent material and glacial history. A stratified random sampling design for baseflow and snowmelt stream water quality based on both hydrogeomorphic region and catchment attributes improves assessments of both reference condition and differences in regional sensitivity. [source] Modelling the species richness distribution of French dung beetles (Coleoptera, Scarabaeidae) and delimiting the predictive capacity of different groups of explanatory variablesGLOBAL ECOLOGY, Issue 4 2002Jorge M. Lobo Abstract Aim To predict French Scarabaeidae dung beetle species richness distribution, and to determine the possible underlying causal factors. Location The entire French territory has been studied by dividing it into 301 grid cells of 0.72 × 0.36 degrees. Method Species richness distribution was predicted using generalized linear models to relate the number of species with spatial, topographic and climate variables in grid squares previously identified as well sampled (n = 66). The predictive function includes the curvilinear relationship between variables, interaction terms and the significant third-degree polynomial terms of latitude and longitude. The final model was validated by a jack-knife procedure. The underlying causal factors were investigated by partial regression analysis, decomposing the variation in species richness among spatial, topographic and climate type variables. Results The final model accounts for 86.2% of total deviance, with a mean jack-knife predictive error of 17.7%. The species richness map obtained highlights the Mediterranean as the region richest in species, and the less well-explored south-western region as also being species-rich. The largest fraction of variability (38%) in the number of species is accounted for by the combined effect of the three groups of explanatory variables. The spatially structured climate component explains 21% of variation, while the pure climate and pure spatial components explain 14% and 11%, respectively. The effect of topography was negligible. Conclusions Delimiting the adequately inventoried areas and elaborating forecasting models using simple environmental variables can rapidly produce an estimate of the species richness distribution. Scarabaeidae species richness distribution seems to be mainly influenced by temperature. Minimum mean temperature is the most influential variable on a local scale, while maximum and mean temperature are the most important spatially structured variables. We suggest that species richness variation is mainly conditioned by the failure of many species to go beyond determined temperature range limits. [source] Methylenetetrahydrofolate reductase gene and risk of Alzheimer's disease in KoreansINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 5 2008Jae-Min Kim Abstract Background The association between methylenetetrahydrofolate reductase (MTHFR) c.677C,>,T (A222V) polymorphism and Alzheimer's disease (AD) is controversial. The objectives of the study were to investigate the association between MTHFR c.677C,>,T polymorphism and AD in Korean elders and to the extent to which it is modified by the major components of one-carbon metabolism and apolipoprotein E (APOE) genotype. Methods Seven hundred and thirty-two community residents aged 65 or over were clinically assessed for AD. Genotyping was performed for MTHFR c.677C,>,T and APOE; serum levels of folate, vitamin B12, and homocysteine were assayed. Age, gender and education were included as covariates. Results A trend of association between TT genotype of MTHFR c.677C,>,T and AD was found [adjusted OR (95% CI): 1.73 (0.80,3.74)]. The association was significant in the presence of below-median vitamin B12 level [3.66 (1.14,11.71)] and in APOE e4 non-carriers [2.97 (1.00,8.55)] with significant interaction terms, and bordered on significance in the presence of above-median homocysteine level [2.73 (0.94,7.90)]. Conclusions These findings suggest gene-environment and gene-gene interactions on the risk of AD in Koreans. Copyright © 2007 John Wiley & Sons, Ltd. [source] Immigration Policy and Employment Conditions of US Immigrants from Mexico, Nicaragua, and the Dominican Republic1INTERNATIONAL MIGRATION, Issue 5 2005Katharine M. Donato ABSTRACT Prior studies suggest that the passage of the Immigration Reform and Control Act (IRCA) in 1986 signalled a deterioration in the labour market conditions of Mexican migrants. In this paper, we examine whether and how labour market conditions worsened for Dominicans and Nicaraguans after 1986, and the extent to which these shifts were comparable to those experienced by Mexicans. Our analysis relies on a new source of data that offers comparable data across the three national origins. We estimate multivariate models that capture the effects of demographic attributes, human and social capital, migration-specific human and social capital, legal status, period of trip, national origin, and other controls on the hourly wages earned by household heads and whether they received cash wages on their last US trip. Models with interaction terms reveal significant pre- and post-1986 wage effects, but few differences in these effects between Mexicans and Dominicans or Nicaraguans. In contrast, group differences appear in the risk of cash receipt of wages. Dominicans and Nicaraguans experienced a greater increase in this risk relative to Mexicans pre- and post-1986. Together, these findings depict a broader, negative impact of IRCA on Latino migrant wages than has been documented elsewhere. [source] New energy terms for reduced protein models implemented in an off-lattice force fieldJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 12 2001Tommi Hassinen Abstract Parameterization and test calculations of a reduced protein model with new energy terms are presented. The new energy terms retain the steric properties and the most significant degrees of freedom of protein side chains in an efficient way using only one to three virtual atoms per amino acid residue. The energy terms are implemented in a force field containing predefined secondary structure elements as constraints, electrostatic interaction terms, and a solvent-accessible surface area term to include the effect of solvation. In the force field the main-chain peptide units are modeled as electric dipoles, which have constant directions in ,-helices and ,-sheets and variable conformation-dependent directions in loops. Protein secondary structures can be readily modeled using these dipole terms. Parameters of the force field were derived using a large set of experimental protein structures and refined by minimizing RMS errors between the experimental structures and structures generated using molecular dynamics simulations. The final average RMS error was 3.7 Å for the main-chain virtual atoms (C, atoms) and 4.2 Å for all virtual atoms for a test set of 10 proteins with 58,294 amino acid residues. The force field was further tested with a substantially larger test set of 608 proteins yielding somewhat lower accuracy. The fold recognition capabilities of the force field were also evaluated using a set of 27,814 misfolded decoy structures. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1229,1242, 2001 [source] | |||||||||||||||||||||||||||||||||||||