Multiple Regression Analysis In Order Research Articles

The association between alcohol consumption patterns and health-related quality of life in a nationally representative sample of South Korean adults.

This study examined the relationship between alcohol consumption and health-related quality of life (HRQOL) in a nationally representative sample of middle-aged to older South Koreans. Data collected from 3,408 men and 3,361 women aged ≥ 40 years were obtained from the 2010 and 2011 Korea National Health and Nutrition Examination Survey. Based on the World Health Organization guidelines, the participants were categorized into zones I (0–7), II (8–15), III (16–19), or IV (20–40) according to their Alcohol Use Disorders Identification Test (AUDIT) scores, with a higher zone indicating a higher level of alcohol consumption. Data collected from the AUDIT and EuroQol 5-Dimension (EQ-5D) test were subjected to multiple regression analysis in order to examine the relationship between alcohol consumption patterns and health-related quality of life, and to identify intersex and interzone differences. Significant intersex differences were found for the mean total AUDIT and EQ-5D scores and the proportion of participants rating their pain/discomfort and impairment in mobility and usual activities as “moderate” or “severe” (p < 0.001). The analysis of the EQ-5D scores by alcohol consumption pattern and sex suggested the existence of an inverted U-shaped relationship between the total AUDIT and EQ-5D scores. The HRQOL of moderate alcohol drinkers was higher than that of non-drinkers and heavy drinkers. The results of this study will be valuable in designing appropriate interventions to increase the HRQOL impaired by the harmful use of alcohol, in comparing HRQOL among different countries, and in implementing alcohol-related health projects.

Role of Exploratory Factor Analysis Applicability of TQM Practices on the Items of Quality Culture in the Kingdom of Saudi Arabia

This study aims to investigate the relationship between Total Quality Management (TQM) practices and quality culture in Kingdom of Saudi Arabia. The samples comprised 388 samples and data was collected through a questionnaire from the managers of leading construction companies in the Kingdom of Saudi Arabia. The respondents were requested to answer self-administered questionnaires, and send their feedback to the researcher, where 5 points rating scale was used to elaborate on varying responses. Additionally, this study employed multiple regression analysis in order to test the relationship between independent variables (TQM practices namely, education and training, customers focus, information and analysis, continuous improvement, process management and top management commitment) and dependent variable (quality culture). The results of this study revealed a positive relationship between education and training and quality culture. In the same path, the results revealed a positive association between customer focus and quality culture and a positive association between information and analysis and quality culture. Additionally, the results also revealed a positive relationship between continuous improvement and quality culture and a positive relationship between process management and quality culture. Finally, the study results showed a positive top management commitment-quality culture relationship. The study provided recommendations and directions for future research.

An investigation on green attitudes and demographics: Understanding the intention of international tourists in Malaysia to pay a premium for green hotels

Lodging industry is one of the most crucial segments that consume a large amount of non-renewable resources. The extant literature shows that a large number of hotels are conducting green performances to offset the shift in customers’ buying behaviour from conventional hotels towards green hotels. Thus, an empirical investigation on hotel customers’ demographic as well as eco-friendly attitudes and intentions can help hotel operators better predict green buying behaviour of their potential/current customers. In this regard, the author conducts a series of multiple regression analyses in order to find any relationships between green attitudes and the intention to pay a premium for green hotels in Malaysia. A total of usable responses were used for data analysis. In general, findings reveal that except for seriousness of environmental problems (SEP), all other green attitudes, applied in this study, have a significant impact on the intention to pay a premium for green hotels. In addition, results of ANOVA indicate a variety of differences in intention to pay a premium for green hotels across different demographic characteristics. Finally, findings of this study not only affirm the Theory of Reasoned Action (TRA) by Ajzen (1975), but also provide managerial implications for hoteliers, marketers, and tourism ministries for better sustainability, segmentation, positioning, and resource allocation.

Influencing factors on carbon reporting: an empirical study in Spanish companies

PurposeThe Carbon Disclosure Project (CDP) has become an international instrument for carbon reporting of companies. The purpose of this paper is to analyze the influence of some factors of the institutional environment of organizations (regulatory pressure, sustainability normative demands and interconnectedness) on the evaluation obtained by Spanish companies in this project.Design/methodology/approachThis paper has proceeded to make a multiple regression analysis in order to analyze the relationship between the dependent variable (“Carbon Disclosure” qualification) and independent variables (regulatory pressure, sustainability normative demands and interconnectedness) supported on the computer programStatistical Package for the Social Sciences(SPSS).FindingsThe results show that the interconnectedness of companies through their participation in associations that fight against climate change is the analyzed factor with a higher predictive power and statistical significance. Also, the regulatory pressure and normative demands from sustainability indexes, such as Dow Jones Sustainability Index, influence the carbon reporting of organizations participating in the CDP.Research limitations/implicationsThe main limitation of this paper is the reduced number of Spanish companies participating in the CDP.Originality/valueThis paper highlights the importance of the role developed by the associations fighting against climate change, since they allow the members to belong to a network through which they share resources, norms and values that positively and significantly influence their behaviour related to carbon reporting.

Use of Health-Related Quality-of-Life Measurements to Estimate Individuals’ Health on Screening

Objectives : to investigate the utility of assessing Health-Related Quality of Life (HRQoL) in a large group of subjects participating in a screening program for aneurysm and the relationship between HRQoL, diagnosis of aneurysm and related risk factors.Methods : subjects involved in this screening program were submitted the EQ-5D questionnaire to report their own HRQoL. HRQoL was reported also a second time by the subjects who were diagnosed with aneurysm during screening and who returned for a monitoring follow up visit a few months later. We evaluated compliance with HRQoL data collection and performed multiple regression analyses in order to investigate the possible relationship between demographic and clinical data with HRQoL.Results : 1,633 subjects screened (6.1% diagnosed with aneurysm) and 125 subjects diagnosed with aneurysm and attending a follow-up visit reported their HRQoL. Completion of the EQ-5D questionnaire was well accepted by both physicians and subjects undergoing screening. HRQoL was not significantly different between the screening and follow - up visits, on adjusting for age and sex. At the screening visit, HRQoL was associated with ASA class, heart condition, BMI and respiratory diseases. No associations were found at the follow-up visit.Conclusion : Assessing HRQoL in screening programs is feasible and well accepted and add useful information on health of large numbers of subjects from general population. This could be considered as a routine approach to optimizing the informative role of screening programs in guiding other investigations or interventions.

Pinpointing outliers in experimental data: the Hat matrix in Anova for fixed and mixed effects models

The Hat (H) matrix and in particular the elements of its principal diagonal (leverages) have a paramount importance in multiple regression analysis in order to pinpoint possible outliers and/or influential points as components of several regression diagnostics. This note presents some features of the H matrix and residuals for ANOVA models of experimental designs. For fixed effects models, the values of the elements of H are discussed in completely randomized, randomized complete block and Latin squares designs. The increasing complexity of the design structure leads to different patterns, with increasing values of the corresponding leverages (hii). For mixed effects models, developments on leverage and residuals for marginal and conditional estimates are illustrated. The application of H matrix and residuals in fixed effects and mixed effects model is shown in a worked example. It is concluded that for H matrix in mixed models, an important role is played by the values of the variances of the random effects and the error term, and, consequently, by their method of estimation. Marginal and conditional studentized residuals provide different information about the data, and thus should be both used for model checking.

Anatomical Distribution of First VTE Event and Risk of VTE Recurrence: Long Term Follow-up and Retrospective Analysis of 346 Patients. Experience From a Single Center

Abstract 1224▪▪This icon denotes a clinically relevant abstractVenous thromboembolism (VTE) is a chronic disease with recurrence risk that persists over the years. Predicting the chance of recurrence on an individual basis is of paramount importance for the appropriate tailoring of anticoagulant therapy. Recurrence risk is affected by thrombophilia and is lower in patients with provoked VTE than in patients with unprovoked thrombosis. Up to date there are no studies focused on the recurrence risk according to the anatomical distribution of the 1st VTE event.In order to evaluate the risk factors of VTE recurrence, after a review of relevant literature we set specific laboratory and clinical variables, which could be associated with VTE recurrence. Moreover, we evaluated retrospectively 346 patients of the Haemostasis Unit, who had already had an episode of VTE concerning the risk of VTE recurrence. Data statistical analysis was done with SPSS package 15.0. At first a monovariable statistical model was used with significance levels set at p= 0.05. For the multivariable statistical analysis model we used all variables with p< 0.1 from the previous model and those mentioned at recent medical literature as significantly related with VTE recurrence.The 346 patients enrolled had already suffered a first episode of VTE and are being followed up regarding VTE recurrence. The study population, 169 (48.7%) male and 178 (51.3%) female, had a mean age at first VTE of 41.54 years. The exclusion criteria of our study were: high risk patients for VTE recurrence who received indefinite anticoagulation (n=72), patients who have suffered VTE and had a follow up period after discontinuation of anticoagulation shorter than 2 years (n=73) and patients who were lost at follow up (n=15). Among 194 patients who were enrolled 108 (55.7%) were women and 86 (44.3%) men, with a mean age at 1st VTE of 40.10 years. 114 patients had only one VTE episode, 59 suffered two, 16 patients had tree episodes and 5 patients had >= 4 episodes.Based on previously published data we tried to define whether the following variables are high risk factors for VTE recurrence in our population: gender, age of diagnosis, thrombophilic factors (FVLeiden, FII, HCY, VIII, AT, PrC, PrS, PAI1, Lp(a), XII), the presence of unprovoked VTE episode and VTE location (DVT, PE, CNS Thrombosis). Male gender p=0,038, FVLeiden homozygous p=0.036, the presence of unprovoked VTE p=0.029, and VTE location p= 0.05 reached statistical significance on a monovariable analysis.Based on the previous analysis and on previously published data we applied gender, age at the time of diagnosis, presence of unprovoked VTE episode and VTE location on a multiple regression analysis in order to define independent risk factors concerning VTE recurrence (Table 1).Table 1Independent Risk factors concerning VTE recurrenceRisk FactorORCI 95%FVLeiden9.7931.07–89.62Unprovoked VTE9.7571.404–5.414Pulmonary embolism11.5321.419–93.746Deep Venus Thrombosis (DVT)17.7932.232–141.841Concerning VTE location, CNS thrombosis has the lowest risk for VTE recurrence and Pulmonary embolism and DVT are independent risk factors compared to the first one.Among VTE events CNS thrombosis and DVT/PE share similarities regarding the transient risk factors and the presence of predisposing thrombophilias. As far as the recurrence risk after a first VTE our study demonstrates ( in agreement with current literature) that CNS thrombosis carries recurrence risk statistically lesser than PE and the highest recurrence risk carry the patients after a first DVT event. Our study is the first observational study regarding recurrence risk after VTE coming from Greece. Disclosures:No relevant conflicts of interest to declare.

Group Factors and its Relationship with Job and Life Satisfaction in Diverse Organizations

This research focuses upon understanding whether the group factors will serve as predictors and explain the variance in individual's job and life satisfaction. A purposive sampling was adopted for the selection of 475 employees from the four different firms having global operations. A structured questionnaire was distributed amongst respondents and data were analyzed with hierarchical stepwise multiple regression analysis in order to assess the extent of variance in job satisfaction and life satisfaction. The results of the analysis indicate that the dimensions of group factors emerged as significant predictors of job satisfaction and life satisfaction in the diverse organizations.

066 Correlates of digital Pulse Amplitude Tonometry (PAT) in middle-aged men and postmenopausal women

Endothelial dysfunction is recognized as an important step in the pathogenesis of cardiovascular disease and in this regard, the assessment of endothelial function is considered an accurate marker of whole-body vascular health status. Among the non-invasive techniques available to evaluate endothelial function, digital pulse amplitude tonometry (PAT) has gained popularity in recent years considering it is an easy to use and reproducible technique. The aim of our study was to investigate the differences in the digital PAT hyperemic response in middle-aged men and postmenopausal women. We measured digital PAT (EndoPAT2000, Itamar Medical, Caesarea, Israel) in a group of 55 men (mean ±SD: 54.7 ± 7.7 years; 29.2 ± 4.3 kg/m2) and 92 postmenopausal women (59.2 ± 4.8 years; 27.5 ± 3.9 kg/m2). Anthropometric measures as well as a fasting plasma lipoprotein-lipid profile were obtained from all participants. We found that the digital reactive hyperemic index (RHI) was significantly lower in men compared to postmenopausal women (2.03 ± 0.59 vs. 2.29 ± 0.69 respectively, P = 0.0194). We also noted that the RHI was negatively correlated with body weight (r = −0.18, P = 0.0253), waist circumference (r = −0.17, P = 0.0388) as well as with the cholesterol/HDL ratio (r = −0.23, P = 0.0061) and positively with circulating HDL-cholesterol levels (r = 0.24, P = 0.0030). Finally, we conducted multiple regression analyses in order to quantify the independent contributions of anthropometric and metabolic variables to the variance of RHI values and found that the latter was best predicted by circulating HDL-cholesterol levels (R2 = 5.9%, P < 0.003). In summary, we found that middle-aged men have a deteriorated digital PAT hyperemic response indicative of an impaired endothelial function compared to postmenopausal women. Furthermore, abdominal obesity and low HDL-cholesterol concentrations were both associated with endothelial dysfunction and HDL-cholesterol was identified as the best predictor of the RHI, although its independent contribution remained of limited extent. Further studies are needed to better understand the role of low HDL-cholesterol levels in endothelial dysfunction as well as to identify other metabolic and nutritional determinants of the RHI in overweight men and women.McCormick Canada Endothelial dysfunction is recognized as an important step in the pathogenesis of cardiovascular disease and in this regard, the assessment of endothelial function is considered an accurate marker of whole-body vascular health status. Among the non-invasive techniques available to evaluate endothelial function, digital pulse amplitude tonometry (PAT) has gained popularity in recent years considering it is an easy to use and reproducible technique. The aim of our study was to investigate the differences in the digital PAT hyperemic response in middle-aged men and postmenopausal women. We measured digital PAT (EndoPAT2000, Itamar Medical, Caesarea, Israel) in a group of 55 men (mean ±SD: 54.7 ± 7.7 years; 29.2 ± 4.3 kg/m2) and 92 postmenopausal women (59.2 ± 4.8 years; 27.5 ± 3.9 kg/m2). Anthropometric measures as well as a fasting plasma lipoprotein-lipid profile were obtained from all participants. We found that the digital reactive hyperemic index (RHI) was significantly lower in men compared to postmenopausal women (2.03 ± 0.59 vs. 2.29 ± 0.69 respectively, P = 0.0194). We also noted that the RHI was negatively correlated with body weight (r = −0.18, P = 0.0253), waist circumference (r = −0.17, P = 0.0388) as well as with the cholesterol/HDL ratio (r = −0.23, P = 0.0061) and positively with circulating HDL-cholesterol levels (r = 0.24, P = 0.0030). Finally, we conducted multiple regression analyses in order to quantify the independent contributions of anthropometric and metabolic variables to the variance of RHI values and found that the latter was best predicted by circulating HDL-cholesterol levels (R2 = 5.9%, P < 0.003). In summary, we found that middle-aged men have a deteriorated digital PAT hyperemic response indicative of an impaired endothelial function compared to postmenopausal women. Furthermore, abdominal obesity and low HDL-cholesterol concentrations were both associated with endothelial dysfunction and HDL-cholesterol was identified as the best predictor of the RHI, although its independent contribution remained of limited extent. Further studies are needed to better understand the role of low HDL-cholesterol levels in endothelial dysfunction as well as to identify other metabolic and nutritional determinants of the RHI in overweight men and women. McCormick Canada

The Impacts of Structural and Psychological Empowerment on Burnout:A Research on Staff Nurses in Turkish State Hospitals

The aim of this study is to examine the relationship between the level of perceived structural and psychological empowerment and the level of burnout among nurses in health service organizations. Data for the present study were taken from the survey of state hospital nurses. This study employs a series of multiple regression analyses in order to address the effect of the level of empowerment on the level of burnout—as well as the effect of the level of each dimension of structural empowerment and psychological empowerment on the each dimension of burnout. The results indicate that nurses who perceive higher level psychological empowerment and lower level structural empowerment and burnout. In addition to the effect of empowerment or the dimensions of empowerment, it was found that various background factors influence the level of burnout perceived by nurses in the workplace.Keywords: Structural Empowerment; Psychological Empowerment; Burnout; Nurses; State Hospital; Turkey

PW01-197 - Social support in patients with chronic combat related PTSD in Croatia

ObjectiveThe main aim of this research is to evaluate the connection of various components of social support with chronic posttraumatic stress disorder (PTSD). We set up hypothesis that the level of the perceived social support mediates beneficial effects on various PTSD symptoms. Second hypothesis states that perceived social support is in positive connection with quality of life.Methods246 outpatients with chronic combat related PTSD participated in this study. On the base of different questionnaires we examined social support, quality of life and PTSD symptomatology (Multidimensional Scale of Perceived Social Support- MSPSS, Trauma symptoms inventory -TSI-A, World Health Organization Quality Of Life-BREF). We tried to identify three main factors of social support by factor analysis of MSPSS. Those factors were used in logistic and multiple regression analysis in order to prove our hypothesis.ResultsIn contrast to other researchers, we defined only two factors in MSPSS: “family support” explaining 52.9% of total variability and “peer support” explaining 18.5% of total variability. These factors used as predictors were not shown significant in multiple regression analysis predicting the PTSD symptoms defined by TSI-A. However, the levels of perceived social support were positively correlated with all four domains of quality of life.ConclusionOur research shows that role of social support in chronic course of PTSD is questionable, possibly due to personality changes and secondary traumatization, which is being supported by other researchers emphasizing it's importance in the early course of PTSD.

Determinants of House Prices in New Zealand

Residential house prices in New Zealand (NZ) have experienced substantial increases even as the rate of house transactions began to slow down in 2007. This paper develops house price forecasting models using multiple regression analysis in order to analyse the main determinants of house prices in the New Zealand market. Quarterly time series data for the period from March 1980 to December 2007 were collected from the Department of Statistics and the Reserve Bank New Zealand for the model development. The estimated model suggests that house prices will fall after 2007 and will continue to fall in 2008 and 2009, and that migration plays an important role in determining house price fluctuation, so that a one-percent increase in migration arrivals is associated with approximately a 10 percent change in house prices with a one-year lag. Investment expectations, unemployment, mortgage rate and building permits are also the main determinants of price variations. The model shows that even before the sub-prime crisis hit NZ, the prices had been on the way down.

Resource allocation analysis for international cooperation program for HIV/AIDS prevention and control

To provide evidence for resource allocation and cooperation between domestic and international HIV/AIDS programs in China by analyzing the needs and current levels of resource input in provinces. National and provincial international cooperation program investment and allocation data from 2000 to 2006 were collected. Several factors in each province were analyzed through multiple regression analysis in order to determine whether they had a statistical correlation to the distribution of international HIV/AIDS program resources in China, including: the Gross Domestic Product (GDP), the number of accumulated people living with HIV/AIDS, and the number of accumulated people living with AIDS. Then the Z values were calculated at each provincial level and compared with related international investment. The resource allocation in different program areas were compared with the level of resource input by international and central government HIV/AIDS prevention and control programs through Chi-square test. The international cooperation program investment at local level from 2000 to 2006 were 4893, 24 669, 50 567, 52 950, 112 143, 363 396 and 247 045 thousand RMB respectively, and at national level were 3007, 19 726, 29 035, 37 530, 77 500, 105 786 and 77 035 thousand RMB respectively. There was a statistical correlation between international HIV/AIDS program resource input and the accumulated number of people living with AIDS (R is 0.56 and 0.69 accordingly, and P < 0.01 both). However, there was no statistical correlation between international resource input and the GDP of each province. International HIV/AIDS cooperation programs did not invest in each province according to its practical needs (R = 0.066, P = 0.725). The international cooperation program investments and needs in different province could not meet completely. The ranks of Z value in Guangdong, Shandong and Jiangsu were 3, 5 and 6, but the ranks of international cooperation program in those provinces were 18, 13 and 28 respectively. The investment proportion for national investment in surveillance and testing, advocacy education and intervention, care and support, and others were 22.4%, 19.7%, 36.8% and 21.1% respectively in 2005, and for international cooperation program were 11.5%, 20.8%, 10.4% and 57.4%. For national investment in 2006 were 18.6%, 23.8%, 32.6% and 25.0%, and international cooperation program were 14.0%, 34.3%, 17.1% and 34.6% respectively. The Chinese government and international programs therefore had different priorities in 2005 (chi(2) = 35.09, P < 0.01) and 2006 (chi(2) = 9.26, P = 0.026). International HIV/AIDS cooperation programs should be better integrated with national programs and combined with epidemic situation and GDP to decide the amount and areas of the investment in order to ensure that they supplement Chinese HIV/AIDS prevention and control activities effectively. The advantages that can be gained from technical support provided by international programs should be further emphasized in line with China's HIV/AIDS prevention and control priorities.

Determinants of burden in those who care for someone with dementia

Caregiver burden is a key measure in caregiver research and is frequently used as a baseline measure in intervention studies. Previous research has found numerous factors associated with caregiver burden such as the relationship quality between carer and patient, the patient's cognitive ability, behavioural and psychological symptoms displayed by the patient, caregiver gender, adverse life events to name a few. Many studies have investigated these factors singularly however current thought suggests a multi-factorial role and inter-dependence of these factors. Based on this it was decided to investigate factors associated with caregiver burden using a multiple regression analysis in order to ascertain the predictive quality of these factors of caregiver burden. Cross-sectional study using validated measures of a patient's cognitive ability, ability to carry out day-to-day tasks and behavioural and psychological symptoms. Caregiver outcomes used are caregiver burden, relationship quality, caregiver confidence, experience of adverse life events, neuroticism, age and gender. Interviews and questionnaires were carried out on 74 patients diagnosed with dementia and their main caregivers from the Midlands of England. Multiple regression analysis showed that caregiver overload, carer-patient relationship quality, the experience of adverse life events, caregiver gender, caregivers' level of neuroticism, caregiver role captivity and the level of caregiver confidence accounted for over 80% of the variance in caregiver burden. These results confirm previous correlational research on caregiver burden. Furthermore, due to the use of multiple regression analysis the findings also show factors that are clear predictors of caregiver burden and we offer possible suggestions from these findings on future clinical practice interventions on caregiver burden.

Alcohol use and abuse in adolescence: proposal of an alternative analysis

A national, representative, school-based sample of Portuguese youths was used to examine the prevalence of alcohol use in this population and to analyse differences between demographic variables such as gender and age, as well as to propose a statistical procedure that optimally quantifies categorical variables. Data on 6109 state school students from Portugal, in the 6th, 8th and 10th grades, aged 11-18, who participated in the 2002 (Health Behaviour in School-aged Children/WHO) survey of adolescent health, were analysed. Adolescents aged between 11 and 14 were placed in the younger group, and those 15-18 years old were placed in the older group. Optimal scaling was used to optimize the computation of factor scores, which were subsequently submitted to multiple regression analysis in order to analyse the impact of gender and age on alcohol use. The results of this study show that the majority of Portuguese school-aged adolescents attending regular school at 6th, 8th and 10th grades do not drink alcoholic beverages (beer, wine or spirits) on a regular basis (at least once a month). However, about 8% of these adolescents do drink beer, 3% do drink wine and 12% do drink spirits on a regular basis. With regard to age and gender, about a quarter of the older boys stated that they drink beer or spirits regularly. The multiple regression analysis showed that age and gender had a significant impact on alcohol use. Alcohol - in particular spirits - is a substance used by some Portuguese adolescents. Alcohol use and abuse is more frequent in boys and increases with age. The importance of these findings for health promotion strategies is discussed.

地域熱供給システムの省エネルギー性評価に関する研究 : 全国123プラントのデータを基にした要因分析とCGS評価手法の検討

In this study the energy performance data of District Heating and Cooling (DHC) plants all over Japan are analyzed with factor analysis and multiple regression analysis in order to verify statistically the factors that effect energy efficiency of DHC plants. In addition, the evaluation methods of Co-Generation System (CGS) are examined to reveal how the discrepancy in the definition of waste heat value from CGS affects energy efficiency. The results lead to the following three conclusions. 1. The operation of heat source equipment is an important factor in all systems. 2. The heat load characteristic affects energy efficiency especially in plants which uses gas as main energy source. 3. The energy efficiency of plants utilizing CGS varies greatly according to evaluation method and actual operation condition of CGS.

Going beyond journal classification for evaluation of research outputs

PurposeSeeks to characterise world astronomy research during the last decade by an analysis of papers in the Science Citation Index identified with a special filter and to study Indian output in order to identify the leading institutions and authors.Design/methodology/approachLists of specialist journals and title words of papers were selected to create a filter giving high precision and recall for astronomy papers. Some biology papers were erroneously retrieved because of ambiguous title words. Potential citation impact was determined from journal citation scores, and multiple regression was used to evaluate leading countries.FindingsTitle words added almost a quarter to the list of papers in specialist journals, and the final file contained over 96,000 papers. Potential impact increased with more authors per paper and more addresses; it was greater for papers from Canada, the UK and the USA, and less for papers from China, India and Russia; for other countries the effects of the author's location on potential impact were not statistically significant. Indian astronomy output has increased in potential impact, partly through greater international co‐authorship, but also through indigenous papers.Research limitations/implicationsThe study was confined to one subject area, and impact was determined on the basis of journals, not of individual papers.Practical implicationsUse of title words in addition to journal lists is essential to sub‐field definition in order to have high precision and recall. Because of the confounding effects of authorship numbers, it is necessary to use multiple regression analysis in order to see whether research from a given country is significantly better or worse than average.Originality/valueCharacterises world astronomy research during the last decade by an analysis of papers in the Science Citation Index identified with a special filter.

Optimisation of a pressurised liquid extraction method for haloanisoles in cork stoppers

Cork taint is a musty off-flavour in wines mainly caused by 2,4,6-trichloroanisole, but other haloanisoles can contribute. In this work, a method for the extraction of 2,4,6-trichloroanisole, 2,4,6-tribromoanisole and 2,6-dichloroanisole has been developed. The procedure involves the extraction of the haloanisoles from cork by pressurised liquid extraction and the analysis of the extracts by both GC–μECD and GC–MS–MS. A central composite design was used to investigate the dependence of the recoveries of the analytes on the temperature, percentage pentane–diethyl ether ratio and the extraction time. Experimental data were then processed by using the multiple regression analysis in order to calculate a mathematical model representing the relationship between factors and responses and to determine the best experimental conditions for PLE method. These conditions corresponded to a temperature of 176 °C, an extraction time between 2.8 and 4 min and an 80:20 pentane:diethyl ether ratio.

Dental age estimation and third molars: a preliminary study

The aim of the present investigation was to reconstruct the chronological age based on the dental developmental stages of third molars evaluated on orthopantomograms. A total of 1175 orthopantomograms were assembled from patients of Caucasian origin between 16 and 22 years of age. Each third molar present was scored by two observers according to a 10-stage developmental scale. The κ statistics measured the intra- and inter-observer reliability. The general statistical analysis was based on multiple regression analysis in order to obtain multiple regression formulas for dental age estimation based on the number of third molars present on the evaluated orthopantomogram. No regression models were statistically significant when there was only one-third molar present because of the relatively small number of orthopantomograms that fitted this criterion. A strong agreement was found between the intra- and inter-observer measurements. The statistical analysis revealed both for males and females high Pearson correlation coefficients between contralateral third molars and smaller coefficients between antimeres. The obtained multiple regression formulas are only applicable in certain specified conditions, for instance when four third molars are present the following formulas should be used in a Caucasian male “age=10.2000+0.5122UL+0.5273LL” (developmental stage of upper and lower left third molars) or in case of a female “age=13.6206+0.1933UR+0.5080LR” (developmental stage of upper and lower right third molars). This investigation revealed that the chronological age of a Caucasian individual may be estimated based on regression formulas with a S.D. of 1.52 or 1.56 years for males and females, respectively, when all four third molars are present.

The distribution of estuarine fish larvae: Nutritional condition andco-occurrence with predators and prey

Fish larvae were collected monthly between March and September 1997 in the Mira and Guadiana estuaries (southern Portugal). Hydrological parameters were registered and zooplankton samples were obtained simultaneously. Densities of fish larvae (ind·100 m -3 ) were calculated from 211 samples and larval nutritional condition measured as RNA/DNA ratios were obtained for 346 individuals, using a fluorimetric method for nucleic acid quantification. Correlating variables were further studied using multiple regression analysis in order to assess the relative importance of abiotic and biotic factors affecting within-year trends in abundance and nutritional condition of estuarine fish larvae. Results indicated that: 1) the abundance of fish larvae seems conditioned by temperature and predation; and 2) their nutritional condition is dependent on temperature and prey availability. Temperature is an important variable structuring estuaries and therefore conditions the behaviour and physiology of fish larvae. Furthermore, the co-occurrence of predators and larvae might be related to similar feeding patterns or comensalism. Whenever feeding conditions are suitable, they usually determine enhanced growth and nutritional condition. However, predation seems to control this latter relationship through its effect on larval mortality. © 2000 Editions scientifiques et medicales Elsevier SAS