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Specific Hypotheses (specific + hypothesis)
Selected AbstractsAn empirical analysis of engineers' information behaviorsJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 4 2010Mark A. Robinson The importance of the acquisition and provision of information within knowledge work such as engineering is widely acknowledged. This article reports an extensive empirical study of such information behaviors in engineers, using a novel and effective work sampling method. Seventy-eight design engineers each carried a portable handheld computer (PDA) for 20 working days. Once every hour, they were prompted to enter data concerning the task they were currently performing, including the information behaviors in which they were engaging. The resultant data represent a comprehensive picture of engineers' information behaviors and the percentage of their working time for which each of these behaviors accounts (55.75% in total). Specific hypotheses concerning the time spent engaged in these behaviors were also tested. Accordingly, it was found that participants spent substantially more time receiving information they had not requested than information they had, and this pattern was also reflected when they provided others with information. Furthermore, although there was no difference found between the time participants spent searching for information from other people compared with nonhuman sources, in the former case they spent relatively less time locating the information source and information within that source, and relatively more time engaged in problem solving and decision making. The results are discussed in terms of their implications for theory and organizational practice. [source] Emphasizing interpersonal factors: an extension of the Witkiewitz and Marlatt relapse modelADDICTION, Issue 8 2009Dorian Hunter-Reel ABSTRACT Aim Recently, Witkiewitz & Marlatt reformulated the Marlatt & Gordon relapse model to account for current research findings. The present paper aims to extend this model further to incorporate social variables more fully. Methods The social-factors and alcohol-relapse literatures were reviewed within the framework of the reformulated relapse model. Results The literature review found that the number of social network members, investment of the individual in the social network, levels of general and alcohol-specific support available within the social network and specific behaviors of network members all predict drinking outcomes. However, little is known about the mechanisms by which these social variables influence outcomes. The authors postulate that social variables influence outcomes by affecting intra-individual factors central to the reformulated relapse prevention model, including processes (e.g. self-efficacy, outcome expectancies, craving, motivation, negative affective states) and behaviors (e.g. coping and substance use). The authors suggest specific hypotheses and discuss methods that can be used to study the impact of social factors on the intra-individual phenomena that contribute to relapse. Conclusion The proposed extension of the relapse model provides testable hypotheses that may guide future alcohol-relapse research. [source] Does size matter for dispersal distance?GLOBAL ECOLOGY, Issue 4 2007David G. Jenkins ABSTRACT Aim, The aim of this study is to answer the questions: (1) do small organisms disperse farther than large, or vice versa; and (2) does the observed pattern differ for passive and active dispersers? These questions are central to several themes in biogeography (including microbial biogeography), macroecology, metacommunity ecology and conservation biology. Location, The meta-analysis was conducted using published data collected worldwide. Methods, We collected and analysed 795 data values in the peer-reviewed literature for direct observations of both maximal dispersal distance and mass of the dispersing organisms (e.g. seeds, not trees). Analysed taxa ranged in size from bacteria to whales. We applied macroecology analyses based on null models (using Monte Carlo randomizations) to test patterns relative to specific hypotheses. Results, Collected dispersal distance and mass data spanned 9 and 21 orders of magnitude, respectively. Active dispersers dispersed significantly farther (P < 0.001) and were significantly greater in mass (P < 0.001) than passive dispersers. Overall, size matters: larger active dispersers attained greater maximum observed dispersal distances than smaller active dispersers. In contrast, passive-disperser distances were random with respect to propagule mass, but not uniformly random, in part due to sparse data available for tiny propagules. Conclusions, Size is important to maximal dispersal distance for active dispersers, but not for passive dispersers. Claims that microbes disperse widely cannot be tested by current data based on direct observations of dispersal: indirect approaches will need to be applied. Distance,mass relationships should contribute to a resolution of neutral and niche-based metacommunity theories by helping scale expectations for dispersal limitation. Also, distance,mass relationships should inform analyses of latitudinal species richness and conservation biology topics such as fragmentation, umbrella species and taxonomic homogenization. [source] Cue reactivity as a predictor of outcome with bulimia nervosaINTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 3 2002Frances A. Carter Abstract The present study sought to evaluate specific hypotheses concerning the relation between cue reactivity and outcome among women with bulimia nervosa. Participants were 135 women aged between 17 and 45 years with a current, primary diagnosis of bulimia nervosa who participated in a randomized clinical trial evaluating the additive efficacy of exposure and nonexposure-based behavior therapy, to a core of cognitive behavior therapy (CBT). Physiological, self-report, and behavioral measures of cue reactivity to individualized high-risk binge foods were obtained at pretreatment and posttreatment. Primary, secondary, and tertiary outcome measures are reported for posttreatment and six-month follow-up. Self-report measures of cue reactivity at posttreatment were significantly positively associated with symptomatology at posttreatment. Cue reactivity at posttreatment was significantly positively associated with symptomatology at 6-month follow-up. However, cue reactivity at posttreatment did not contribute to the prediction of outcome at follow-up over and above posttreatment outcome. The notion that pretreatment cue reactivity may predict which treatment modality will be most beneficial (exposure or nonexposure-based treatment), as measured by reductions in symptomatology at posttreatment could not be supported. Implications for future research are discussed. © 2002 by Wiley Periodicals, Inc. Int J Eat Disord 31: 240,250, 2002; DOI 10.1002/eat.10041 [source] Return Migration by German Guestworkers: Neoclassical versus New Economic TheoriesINTERNATIONAL MIGRATION, Issue 4 2002Amelie Constant Neoclassical economics and the new economics of labour migration posit very different motivations for international migration. The former assumes that people move abroad permanently to maximize lifetime earnings whereas the latter assumes they leave temporarily to overcome market deficiencies at home. As a result, the two models yield very different conceptualizations of return migration. We draw upon each theoretical model to derive predictions about how different variables are likely to influence the probability of return migration. We use data from the German Socio,economic Panel to test specific hypotheses derived from each model. Finding some support for both perspectives, we suggest that migrants may be heterogeneous with respect to their migratory motivations. If so, then parameters associated with the determinants of return migration in any population of international migration will reflect a blending of parameters associated with two distinct economic rationales. Equations estimated separately for remitting and non,remitting migrants lend support to this interpretation, meaning there may not be one unitary process of return migration, but several. [source] Consumer stress-handling strategies: theory and research findingsJOURNAL OF CONSUMER BEHAVIOUR, Issue 3 2006Anil Mathur Although stress research has received increased attention in the behavioral and social sciences, it has been virtually ignored by marketing and consumer researchers. This paper attempts to advance the concept of stress as a viable construct in consumer studies. A conceptual model is developed based on theory and research, and cross-sectional and longitudinal data are used to test specific hypotheses, producing results consistent with the general stress model. Copyright © 2006 John Wiley & Sons, Ltd. [source] Preferences for Third-Party Help in Workplace Conflict: A Cross-Cultural Comparison of Chinese and Dutch EmployeesNEGOTIATION AND CONFLICT MANAGEMENT RESEARCH, Issue 4 2009Ellen Giebels Abstract This study examines conflict parties' preferences for different types of third-party help and how this may be influenced by cultural differences in terms of individualism/collectivism. We focus our analysis on process-related nonsubstantive help and identify three types of third-party help in interpersonal conflict situations: relational help, procedural help, and emotional help. In a pilot study with Chinese and Dutch students (N = 93), we first developed and validated three new scales to measure preferences for the three types of third-party help. To further test specific hypotheses we used another sample of Dutch and Hong Kong Chinese bank employees (N = 71). In line with our expectations, Chinese employees report a higher preference for relational help, while Dutch employees report a higher preference for emotional help. In terms of procedural help, there was no significant difference between Dutch and Chinese employees. Furthermore, additional analyses revealed a gender effect on the preference for emotional help, showing that,regardless of their cultural background,females prefer this type of third-party help more, presumably because they experience more conflict stress. [source] Why Does head form change in children of immigrants?AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2010A reappraisal Objectives: We test two specific hypotheses that explain the cranial changes Boas observed in Hebrews and Sicilians, namely that Hebrew change results from abandoning cradling of infants in America, while in Sicilians it results from impaired growth in America. Methods: Boas's (1928) data were used to test these hypotheses. The role of cradling in cranial shape was examined by comparing cranial indices of U.S.-born and foreign children between 1.5 and 5 years of age. Age changes in cranial index of Hebrew and Sicilian children ages five to eighteen were examined to demonstrate differing patterns of age changes, which could be explained by environmental differences. Statistical methods employed were t -tests, least squares, and loess regression. Results: The difference between American and foreign-born Hebrew children arose prior to five years of age, after which it remained constant. American and foreign-born Sicilians, on the other hand, had similar cranial indices at age five, and diverged during the growing years, primarily because American-born children did not exhibit the reduction in cranial index with age seen in the other groups. Conclusions: The results support the two hypotheses tested. Change in Hebrew cranial indices resulted from abandoning the practice of cradling infants in America. U.S.-born Sicilian children experienced an environment worse than the one in Europe, and consequently experienced impaired growth. We conclude that the changes Boas observed resulted from specific behavioral and economic conditions unique to each group, rather than a homogeneous American environment. Am. J. Hum. Biol. 22:702-707, 2010. © 2010Wiley-Liss, Inc. [source] The obligatory role of the kidney in long-term arterial blood pressure control: extending Guyton's model of the circulationANAESTHESIA, Issue 11 2009K. L. Dorrington Summary We describe a model for the essential role of the kidney in long-term blood pressure regulation. We begin with a simple hydraulic model for the circulation, with a constant circulating volume. We show, with the help of a modification of Guyton's classic diagram, that cardiac output and mean arterial pressure are functions of circulating volume, peripheral resistance, venous and arterial compliances, and the cardiac Starling curve. This approach models only acute changes in a ,closed' circulation , one where there is no intake or excretion of fluid. The model is then adapted to ,open' the circulation, include a role for the kidney, and represent more chronic changes. Arterial pressure is then a sole function of renal behaviour and daily sodium (and liquid) intake, and becomes independent of other cardiovascular variables. As well as generating specific hypotheses for further investigation, these models can be used for the purpose of education in cardiovascular control and the treatment of hypertension. [source] Are Statistical Contributions to Medicine Undervalued?BIOMETRICS, Issue 1 2003Norman E. Breslow Summary. Econometricians Daniel McFadden and James Heckman won the 2000 Nobel Prize in economics for their work on discrete choice models and selection bias. Statisticians and epidemiologists have made similar contributions to medicine with their work on case-control studies, analysis of incomplete data, and causal inference. In spite of repeated nominations of such eminent figures as Bradford Hill and Richard Doll, however, the Nobel Prize in physiology and medicine has never been awarded for work in biostatistics or epidemiology. (The "exception who proves the rule" is Ronald Ross, who, in 1902, won the second medical Nobel for his discovery that the mosquito was the vector for malaria. Ross then went on to develop the mathematics of epidemic theory,which he considered his most important scientific contribution,and applied his insights to malaria control programs.) The low esteem accorded epidemiology and biostatistics in some medical circles, and increasingly among the public, correlates highly with the contradictory results from observational studies that are displayed so prominently in the lay press. In spite of its demonstrated efficacy in saving lives, the "black box" approach of risk factor epidemiology is not well respected. To correct these unfortunate perceptions, statisticians would do well to follow more closely their own teachings: conduct larger, fewer studies designed to test specific hypotheses, follow strict protocols for study design and analysis, better integrate statistical findings with those from the laboratory, and exercise greater caution in promoting apparently positive results. [source] Birth Defects Cluster Study: A national approach to birth defects cluster investigations,,BIRTH DEFECTS RESEARCH, Issue 11 2008James E. Kucik Abstract BACKGROUND: Investigations of clusters of birth defects have been challenging endeavors that have had only modest success identifying causes or risk factors. Some of the challenges to individual cluster investigations have been small sample size and limited data collection. We describe a novel approach for investigating and analyzing pooled information from a series of birth defects cluster investigations. METHODS: The Birth Defects Cluster Study uses a case-control study design with standardized methods, including a case definition, control selection, data collection methods, and data collected (e.g., maternal interviews, blood samples, and environmental samples). Analyses of pooled data from several clusters of the same defect are conducted for specific hypotheses once a sufficient sample size has been achieved. The feasibility of conducting individual birth defect investigations was evaluated on a cluster of gastroschisis. RESULTS: The pilot investigation of a cluster of gastroschisis demonstrated success in recruiting participants and in collecting data and specimens for eventual inclusion in a pooled analysis. CONCLUSIONS: The Birth Defects Cluster Study offers a unique and effective approach to cluster investigations that improves the likelihood of identifying genetic and environmental causes of birth defects and provides a model for cluster investigations of other noninfectious health outcomes. Birth Defects Research (Part A), 2008. Published 2008 Wiley-Liss, Inc. [source] How do mothers' childrearing histories, stress and parenting affect children's behavioural outcomes?CHILD: CARE, HEALTH AND DEVELOPMENT, Issue 5 2002M. A. Assel Abstract Background Information is needed to understand the role of low to moderate levels of mothers' emotional stress and child characteristics (i.e. prematurity) on parenting behaviours and their impact on children's behaviour that might be deemed ,challenging' but not ,disordered'. Methods The direct and indirect relations of maternal childrearing history and emotional stress, and observed parenting practices when children were 3 years of age on 4-year child behavioural outcomes was examined in a sample of low-income families with a term (n = 112) or preterm (n = 180) child. Parenting practices included displays of warmth and restrictiveness when interacting with their children. Child outcomes at 4 years included observation of social initiations with their mothers and maternal report of social and attentional problems. Results A Structural Equation Model building approach guided by specific hypotheses indicated that preterm as compared to full-term children had more maternal reported social and attentional problems but did not differ in observed social initiating skills. Greater negative maternal childrearing history indirectly influenced social initiating skills through its direct influence on maternal emotional stress. Greater maternal emotional stress directly influenced mothers' parenting that, in turn, directly influenced social initiating. Prematurity and a more negative childrearing history had a direct negative influence on the maternal report of social and attentional behavioural outcomes. Conclusions These findings delineate the effects of prematurity and maternal parenting on the behaviour of 4-year-old-children and extend current knowledge of the influence of parental emotional stress on parenting. Even milder levels can negatively influence parenting, and in turn, contribute to children's less well developed social skills. The issues raised in this study could help with the identification and prioritization of medical and psychological services. [source] Resource and non-resource root competition effects of grasses on early- versus late-successional treesJOURNAL OF ECOLOGY, Issue 3 2009Christian Messier Summary 1This study assessed the effects of resource (i.e. nutrients) and non-resource (i.e. interference for space) competition from fine roots of competing grasses on the growth, morphology and architecture of fine roots of four tree species of varying successional status: Populus deltoides ¥ P. balsamifera (a hybrid), Betula papyrifera, Acer saccharum and Fraxinus americana. We tested the general hypothesis that tree fine-roots are affected by both below-ground resource and non-resource competition from non-self plants, and the more specific hypothesis that this effect is stronger in early-successional tree species. 2The experiment was conducted in split-containers where half of the roots of tree seedlings experienced either below-ground resource competition or non-resource competition, or both, by grasses while the other half experienced no competition. 3The late-successional tree species A. saccharum and F. americana were mostly affected by resource competition, whereas the early-successional P. deltoides¥balsamifera and B. papyrifera were strongly affected by both resource and non-resource competition. Non-resource competition reduced fine-root growth, root branching over root length (a measure of root architecture) and specific root length (a measure of root morphology) of both early-successional species. 4Synthesis. This study suggests that early-successional tree species have been selected for root avoidance or segregation and late-successional tree species for root tolerance of competition as mechanisms to improve below-ground resource uptake in their particular environments. It also contradicts recent studies showing perennial and annual grasses tend to overproduce roots in the presence of non-self conspecific plants. Woody plants, required to grow and develop for long periods in the presence of other plants, may react differently to non-self root competition than perennial or annual grasses that have much shorter lives. [source] Compressive compared with tensile loading of medial collateral ligament scar in vitro uniquely influences mRNA levels for aggrecan, collagen type II, and collagenaseJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2000Tokifumi Majima To test the hypothesis that loading conditions can be used to engineer early ligament scar behaviors, we used an in vitro system to examine the effect that cyclic hydrostatic compression and cyclic tension applied to 6-week rabbit medial collateral ligament scars had on mRNA levels for matrix molecules, collagenase, and the proto-oncogenes c-fos and c-jun. Our specific hypothesis was that tensile stress would promote more normal mRNA expression in ligament whereas compression would lead to higher levels of mRNA for cartilage-like molecules. Femur (injured medial collateral ligament)-tibia complexes were subjected to a hydrostatic pressure of 1 MPa or a tensile stress of 1 MPa of 0.5 Hz for 1 minute followed by 14 minutes of rest. On the basis of a preliminary optimization experiment, this 15-minute testing cycle was repeated for 4 hours. Semiquantitative reverse transcription-polymerase chain reaction analysis was performed for mechanically treated medial collateral ligament scars with use of rabbit specific primer sets for types I, II, and III collagen, decorin, biglycan, fibromodulin, versican, aggrecan, collagenase, c-fos, c-jun, and a housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase. Cyclic hydrostatic compression resulted in a statistically significant increase in mRNA levels of type-II collagen (171% of nonloaded values) and aggrecan (313% of nonloaded values) but statistically significant decreases in collagenase mRNA levels (35% of nonloaded values). Cyclic tension also resulted in a statistically significant decrease in collagenase mRNA levels (66% of nonloaded values) and an increase in aggrecan mRNA levels (458% of nonloaded values) but no significant change in the mRNA levels for the other molecules. The results show that it is possible to alter mRNA levels for a subset of genes in scar tissue by supplying unique mechanical stimuli in vitro and thus that further investigation of scar engineering for potential reimplantation appears feasible. [source] Antenatal home blood pressure monitoring: a pilot randomised controlled trialBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 2 2000H. Ross-McGill Research Midwife Objective To measure recruitment to, compliance with, and the acceptability of a trial designed to test whether a reduced schedule of antenatal visits combined with training in self-measurement of blood pressure at home may improve hypertension screening and save money. To test the specific hypothesis that even after taking into account extra unscheduled visits, the reduced schedule with ambulatory monitoring reduces total visits. Design A pilot randomised controlled trial. Setting Four urban and four rural general practices in Yorkshire and Lancashire. Population One hundred and five low risk women in the third trimester of pregnancy. Eighty women participated. Intervention Women were invited to participate at 24,28 weeks. Those who accepted were allocated either to a standard nine subsequent visit schedule (30, 32, 34, 36, 37, 38, 39, 40, 41 weeks) or to a reduced schedule (34, 38, 41 weeks). Those in the latter group measured their blood pressure weekly using a portable sphygmomanometer at home. Main outcome measures Recruitment, total number of clinic visits, frequency of blood pressure measurement, schedule preference, and anxiety. Results Although there were more unscheduled visits in the home monitoring group, this did not outweigh the reduction in scheduled visits, (total visits reduced from 7.4 to 4.5, P < 0.001), and blood pressure was measured during more weeks (9 vs 7 weeks, P < 0.001) in the experimental group. Most women expressed a preference for the reduced schedule both when the idea was first suggested, and after they had experienced it, and there were no significant differences in anxiety. Conclusion Replacement of antenatal screening visits with home blood pressure monitoring is acceptable to women. The reduction in clinic visits is not compensated by an increase in visits for other reasons and overall blood pressure measurement is omitted less often. Whether it reduces adverse outcomes or has any rare side effects will require a larger trial, but this pilot study indicates that it is likely to be safe, and that such a large trial would be feasible. [source] | |||||||||||||||||||