849 resultados para large sample distributions
Resumo:
Both predators and parasites can elicit behavioral and physiological responses in prey and hosts, respectively. These responses may involve the reallocation of resources and may thus limit each other. We investigated the effects of concurrent pre-laying exposure of great tit females (Parus major) to both a simulated predation risk and a nest-based ectoparasite, the hen flea (Ceratophyllus gallinae), on nestling growth and development. We manipulated perceived predation risk using models and vocalizations of sparrowhawks (Accipiter nisus). At the start of incubation, we swapped whole clutches between treated and untreated nests to separate pre-laying maternal effects from posthatching effects. Since costs and benefits of maternal responses to parasites need to be assessed under parasite pressure, we infested half of the rearing nests with hen fleas. Parasites had negative effects on mass gain and wing growth, both via maternal effects and via direct exposure of nestlings, whereas maternal predation risk had no significant effect. The interaction between predator and parasite treatments was not significant and, thus, suggests the absence of a trade-off between the 2 stressors operating at the level of maternal effects. Alternatively, the complexity of the design, despite a relatively large sample size, may have limited the power for detection of this expected trade-off.
Resumo:
INTRODUCTION Recent meta-analyses of the outcome of apical surgery using modern techniques including microsurgical principles and high-power magnification have yielded higher rates of healing. However, the information is mainly based on 1- to 2-year follow-up data. The present prospective study was designed to re-examine a large sample of teeth treated with apical surgery after 5 years. METHODS Patients were recalled 5 years after apical surgery, and treated teeth were classified as healed or not healed based on clinical and radiographic examination. (The latter was performed independently by 3 observers). Two different methods of root-end preparation and filling (primary study parameters) were to be compared (mineral trioxide aggregate [MTA] vs adhesive resin composite [COMP]) without randomization. RESULTS A total of 271 patients and teeth from a 1-year follow-up sample of 339 could be re-examined after 5 years (dropout rate = 20.1%). The overall rate of healed cases was 84.5% with a significant difference (P = .0003) when comparing MTA (92.5%) and COMP (76.6%). The evaluation of secondary study parameters yielded no significant difference for healing outcome when comparing subcategories (ie, sex, age, type of tooth treated, post/screw, type of surgery). CONCLUSIONS The results from this prospective nonrandomized clinical study with a 5-year follow-up of 271 teeth indicate that MTA exhibited a higher healing rate than COMP in the longitudinal prognosis of root-end sealing.
Resumo:
This study analyzed the influence of the occupational context on the conceptualization of career satisfaction measured by the career satisfaction scale (CSS). In a large sample of N ¼ 729 highly educated professionals, a cross-occupational (i.e., physicians, economists, engineers, and teachers) measurement invariance analysis showed that the CSS was conceptualized according to occupational group membership, that is, 4 of the 5 items of the scale showed measurement noninvariance. More specifically, the relative importance, the response biases, and the reliabilities associated with different career satisfaction content domains measured by the CSS (i.e., achieved success, overall career goals, goals for advancement, goals for income, and goals for development of new skills) varied by occupational context. However, results of a comparison between manifest and latent mean differences between the occupational groups revealed that the observed measurement noninvariance did not affect the estimation of mean differences.
Resumo:
BACKGROUND Patients requiring anticoagulation suffer from comorbidities such as hypertension. On the occasion of INR monitoring, general practitioners (GPs) have the opportunity to control for blood pressure (BP). We aimed to evaluate the impact of Vitamin-K Antagonist (VKA) monitoring by GPs on BP control in patients with hypertension. METHODS We cross-sectionally analyzed the database of the Swiss Family Medicine ICPC Research using Electronic Medical Records (FIRE) of 60 general practices in a primary care setting in Switzerland. This database includes 113,335 patients who visited their GP between 2009 and 2013. We identified patients with hypertension based on antihypertensive medication prescribed for ≥6 months. We compared patients with VKA for ≥3 months and patients without such treatment regarding BP control. We adjusted for age, sex, observation period, number of consultations and comorbidity. RESULTS We identified 4,412 patients with hypertension and blood pressure recordings in the FIRE database. Among these, 569 (12.9 %) were on Phenprocoumon (VKA) and 3,843 (87.1 %) had no anticoagulation. Mean systolic and diastolic BP was significantly lower in the VKA group (130.6 ± 14.9 vs 139.8 ± 15.8 and 76.6 ± 7.9 vs 81.3 ± 9.3 mm Hg) (p < 0.001 for both). The difference remained after adjusting for possible confounders. Systolic and diastolic BP were significantly lower in the VKA group, reaching a mean difference of -8.4 mm Hg (95 % CI -9.8 to -7.0 mm Hg) and -1.5 mm Hg (95 % CI -2.3 to -0.7 mm Hg), respectively (p < 0.001 for both). CONCLUSIONS In a large sample of hypertensive patients in Switzerland, VKA treatment was independently associated with better systolic and diastolic BP control. The observed effect could be due to better compliance with antihypertensive medication in patients treated with VKA. Therefore, we conclude to be aware of this possible benefit especially in patients with lower expected compliance and with multimorbidity.
Resumo:
The identification of quantitative trait loci (QTL) such as height and their underlying causative variants is still challenging and often requires large sample sizes. In humans hundreds of loci with small effects control the heritable portion of height variability. In domestic animals, typically only a few loci with comparatively large effects explain a major fraction of the heritability. We investigated height at withers in Shetland ponies and mapped a QTL to ECA 6 by genome-wide association (GWAS) using a small cohort of only 48 animals and the Illumina equine SNP70 BeadChip. Fine-mapping revealed a shared haplotype block of 793 kb in small Shetland ponies. The HMGA2 gene, known to be associated with height in horses and many other species, was located in the associated haplotype. After closing a gap in the equine reference genome we identified a non-synonymous variant in the first exon of HMGA2 in small Shetland ponies. The variant was predicted to affect the functionally important first AT-hook DNA binding domain of the HMGA2 protein (c.83G>A; p.G28E). We assessed the functional impact and found impaired DNA binding of a peptide with the mutant sequence in an electrophoretic mobility shift assay. This suggests that the HMGA2 variant also affects DNA binding in vivo and thus leads to reduced growth and a smaller stature in Shetland ponies. The identified HMGA2 variant also segregates in several other pony breeds but was not found in regular-sized horse breeds. We therefore conclude that we identified a quantitative trait nucleotide for height in horses.
Resumo:
Purpose – A growing body of literature provides evidence for the efficacy of workplace health promotion (WHP). However, little is known about effective dissemination strategies for WHP interventions. The purpose of this paper is to describe how a WHP agency in Zurich, Switzerland, used bulk mailings, information events, telephone marketing and free initial consultations for the large-scale geographic marketing of WHP services, with a focus on tobacco prevention (TP). Design/methodology/approach – To analyze the number of companies responding positively to solicitation, examine the predictors of positive responses and explore the reasons for negative responses, the authors used both quantitative (e.g. a standardized questionnaire) and qualitative (telephone interviews) methods. Findings – The results show that except for telephone marketing (69 percent), the success rates of dissemination activities were very low (3-9 percent). Predictors for a positive response were institutionalization of WHP, the representative’s personal concern about TP, and problems with environmental tobacco smoke within the company. The most prominent reason for a negative Response was that the companies had already implemented TP measures by themselves and needed no further external support. Practical implications – It is suggested that TP was the wrong emphasis for a WHP program to be disseminated at that particular time, because a law on protection from passive smoking was introduced in Switzerland shortly afterwards. Originality/value – The study examines dissemination strategies under real-life Consulting conditions. It builds on on a large sample of companies and uses both quantitative and qualitative research methods. It reports specific numbers and success rates of marketing activities and thereby contributes to the knowledge about an important issue for intervention planning in the field of WHP.
Resumo:
Old captains at the helm: Chairman age and firm performance Urs Waelchli and Jonas Zeller December, 2012 This paper examines whether the chairmen of the board (COBs) impose their life-cycles on the firms over which they preside. Using a large sample of unlisted firms we find a robust negative relation between COB age and firm performance. COBs age much like ‘ordinary’ people. Their cognitive abilities deteriorate and they experience significant shifts in motivation. Deteriorating cognitive abilities are the main driver of the performance effect that we observe. The results imply that succession planning problems in unlisted firms are real. Mandatory retirement age clauses cannot solve these problems. Corporate Aging around the World Jonas Zeller January, 2014 This paper examines whether firms internationally age as US firms do (Loderer, Stulz, and Wälchli, 2013). Using a large panel, I find that Tobin’s Q monotonically falls with firm Age across all nineteen countries in the sample. The decrease varies across countries but is generally extremely robust and economically significant. ROA, sales growth, and market share decrease over a firm’s lifetime in most countries as well. Furthermore, older firms reduce their capital expenditures and R&D outlays. Instead, they distribute more cash to their shareholders. Overall, the results suggest that corporate aging is not confined to the US but is a genuine phenomenon that affects listed firms worldwide. This evidence supports the hypothesis that corporate aging is driven by managers who optimally focus on managing their assets in place and neglect the development of growth opportunities. I finally ask whether the managers’ choice and with it the magnitude of the decline in Tobin’s Q is a function of country-level institutional settings. I find that most notably firms age faster in countries where employees are relatively well protected by labor regulation. Is employment protection the fountain of corporate youth? Claudio Loderer, Urs Wälchli, Jonas Zeller* September 2014 Acharya, Baghai, and Subramanian (2012, 2013) find that employment protection legislation (EPL) encourages innovation. We argue that this effect should be particularly strong in mature firms. We would therefore also expect EPL to boost growth opportunities. Using the natural Experiment created by the staggered passage of changes in EPL across seventeen countries, we find evidence that employment protection legislation does indeed stimulate Innovation efforts, especially in mature firms. The effect is stronger in countries in which patents are owned by the firm and in the context of regular contracts. Consistent with that, EPL encourages risk taking. Overall, however, there is Little evidence that the effect of EPL on innovation effort translates into higher firm value, not even in mature firms. EPL does motivate employees in those firms to put in a greater effort, as evidenced by stronger sales growth. Yet it also increases costs, reduces profitability, and depresses Tobin’s Q ratios in all firms, especially the mature ones, possibly because of the rigidities that characterize these firms [Loderer, Stulz, and Waelchli (2014)].
Resumo:
During intertemporal decisions, the preference for smaller, sooner reward over larger-delayed rewards (temporal discounting, TD) exhibits substantial inter-subject variability; however, it is currently unclear what are the mechanisms underlying this apparently idiosyncratic behavior. To answer this question, here we recorded and analyzed mouse movement kinematics during intertemporal choices in a large sample of participants (N = 86). Results revealed a specific pattern of decision dynamics associated with the selection of “immediate” versus “delayed” response alternatives, which well discriminated between a “discounter” versus a “farsighted” behavior—thus representing a reliable behavioral marker of TD preferences. By fitting the Drift Diffusion Model to the data, we showed that differences between discounter and farsighted subjects could be explained in terms of different model parameterizations, corresponding to the use of different choice mechanisms in the two groups. While farsighted subjects were biased toward the “delayed” option, discounter subjects were not correspondingly biased toward the “immediate” option. Rather, as shown by the dynamics of evidence accumulation over time, their behavior was characterized by high choice uncertainty.
Resumo:
The most commonly used method for formally assessing grapheme-colour synaesthesia (i.e., experiencing colours in response to letter and/or number stimuli) involves selecting colours from a large colour palette on several occasions and measuring consistency of the colours selected. However, the ability to diagnose synaesthesia using this method depends on several factors that have not been directly contrasted. These include the type of colour space used (e.g., RGB, HSV, CIELUV, CIELAB) and different measures of consistency (e.g., city block and Euclidean distance in colour space). This study aims to find the most reliable way of diagnosing grapheme-colour synaesthesia based on maximising sensitivity (i.e., ability of a test to identify true synaesthetes) and specificity (i.e., ability of a test to identify true non-synaesthetes). We show, applying ROC (Receiver Operating Characteristics) to binary classification of a large sample of self-declared synaesthetes and non-synaesthetes, that the consistency criterion (i.e., cut-off value) for diagnosing synaesthesia is considerably higher than the current standard in the field. We also show that methods based on perceptual CIELUV and CIELAB colour models (rather than RGB and HSV colour representations) and Euclidean distances offer an even greater sensitivity and specificity than most currently used measures. Together, these findings offer improved heuristics for the behavioural assessment of grapheme-colour synaesthesia.
Resumo:
UNLABELLED We previously showed that close relatives of human coronavirus 229E (HCoV-229E) exist in African bats. The small sample and limited genomic characterizations have prevented further analyses so far. Here, we tested 2,087 fecal specimens from 11 bat species sampled in Ghana for HCoV-229E-related viruses by reverse transcription-PCR (RT-PCR). Only hipposiderid bats tested positive. To compare the genetic diversity of bat viruses and HCoV-229E, we tested historical isolates and diagnostic specimens sampled globally over 10 years. Bat viruses were 5- and 6-fold more diversified than HCoV-229E in the RNA-dependent RNA polymerase (RdRp) and spike genes. In phylogenetic analyses, HCoV-229E strains were monophyletic and not intermixed with animal viruses. Bat viruses formed three large clades in close and more distant sister relationships. A recently described 229E-related alpaca virus occupied an intermediate phylogenetic position between bat and human viruses. According to taxonomic criteria, human, alpaca, and bat viruses form a single CoV species showing evidence for multiple recombination events. HCoV-229E and the alpaca virus showed a major deletion in the spike S1 region compared to all bat viruses. Analyses of four full genomes from 229E-related bat CoVs revealed an eighth open reading frame (ORF8) located at the genomic 3' end. ORF8 also existed in the 229E-related alpaca virus. Reanalysis of HCoV-229E sequences showed a conserved transcription regulatory sequence preceding remnants of this ORF, suggesting its loss after acquisition of a 229E-related CoV by humans. These data suggested an evolutionary origin of 229E-related CoVs in hipposiderid bats, hypothetically with camelids as intermediate hosts preceding the establishment of HCoV-229E. IMPORTANCE The ancestral origins of major human coronaviruses (HCoVs) likely involve bat hosts. Here, we provide conclusive genetic evidence for an evolutionary origin of the common cold virus HCoV-229E in hipposiderid bats by analyzing a large sample of African bats and characterizing several bat viruses on a full-genome level. Our evolutionary analyses show that animal and human viruses are genetically closely related, can exchange genetic material, and form a single viral species. We show that the putative host switches leading to the formation of HCoV-229E were accompanied by major genomic changes, including deletions in the viral spike glycoprotein gene and loss of an open reading frame. We reanalyze a previously described genetically related alpaca virus and discuss the role of camelids as potential intermediate hosts between bat and human viruses. The evolutionary history of HCoV-229E likely shares important characteristics with that of the recently emerged highly pathogenic Middle East respiratory syndrome (MERS) coronavirus.
Resumo:
Aims. The main goal of this work is to study element ratios that are important for the formation of planets of different masses. Methods. We study potential correlations between the existence of planetary companions and the relative elemental abundances of their host stars. We use a large sample of FGK-type dwarf stars for which precise Mg, Si, and Fe abundances have been derived using HARPS high-resolution and high-quality data. Results. A first analysis of the data suggests that low-mass planet host stars show higher [Mg/Si] ratios, while giant planet hosts present [Mg/Si] that is lower than field stars. However, we found that the [Mg/Si] ratio significantly depends on metallicity through Galactic chemical evolution. After removing the Galactic evolution trend only the difference in the [Mg/Si] elemental ratio between low-mass planet hosts and non-hosts was present in a significant way. These results suggest that low-mass planets are more prevalent around stars with high [Mg/Si]. Conclusions. Our results demonstrate the importance of Galactic chemical evolution and indicate that it may play an important role in the planetary internal structure and composition. The results also show that abundance ratios may be a very relevant issue for our understanding of planet formation and evolution.
Resumo:
Parasites and pathogens are apparent key factors for the detrimental health of managed European honey bee subspecies, Apis mellifera. Apicultural trade is arguably the main factor for the almost global distribution of most honey bee diseases, thereby increasing chances for multiple infestations/infections of regions, apiaries, colonies and even individual bees. This imposes difficulties to evaluate the effects of pathogens in isolation, thereby creating demand to survey remote areas. Here, we conducted the first comprehensive survey for 14 honey bee pathogens in Mongolia (N = 3 regions, N = 9 locations, N = 151 colonies), where honey bee colonies depend on humans to overwinter. In Mongolia, honey bees, Apis spp., are not native and colonies of European A. mellifera subspecies have been introduced ~60 years ago. Despite the high detection power and large sample size across Mongolian regions with beekeeping, the mite Acarapis woodi, the bacteria Melissococcus plutonius and Paenibacillus larvae, the microsporidian Nosema apis, Acute bee paralysis virus, Kashmir bee virus, Israeli acute paralysis virus and Lake Sinai virus strain 2 were not detected, suggesting that they are either very rare or absent. The mite Varroa destructor, Nosema ceranae and four viruses (Sacbrood virus, Black queen cell virus, Deformed wing virus (DWV) and Chronic bee paralysis virus) were found with different prevalence. Despite the positive correlation between the prevalence of V. destructor mites and DWV, some areas had only mites, but not DWV, which is most likely due to the exceptional isolation of apiaries (up to 600 km). Phylogenetic analyses of the detected viruses reveal their clustering and European origin, thereby supporting the role of trade for pathogen spread and the isolation of Mongolia from South-Asian countries. In conclusion, this survey reveals the distinctive honey bee pathosphere of Mongolia, which offers opportunities for exciting future research.
Resumo:
Background. The prevalence of obesity and overweight children has been an ongoing health epidemic in the US for the last several decades. The problem has consistently worsened and has disproportionately been the most prevalent among low socioeconomic status (SES) populations. Food availability in the home has been suggested to be a potential factor related to overweight and obesity, as availability is likely associated with intake. Food availability of low SES preschool aged children has not been well examined. The purpose of this study was to explore the food environment of the Harris County Department of Education (HCDE) Head Start population, and describe reported frequency of intake of particular food groups. The effect of food availability on reported intake was also examined.^ Methods. This was a cross-sectional study of secondary data analysis. Data obtained from 17 HCDE Head Start Centers was analyzed using PASW 18 Statistical Software. Demographic analyses included population, age, gender, race, parent occupation, type of home, and language spoken in the home. Descriptive statistics included reported availability of foods in the home as well as frequency of intake.^ Regression analysis examined the relationship of availability of foods on intake. The food categories included were: dark leafy green and orange vegetables, other vegetables, fruits, soda, salty snacks, and sweet snacks. For both vegetable categories reported intake of fresh, frozen, and canned vegetables were included. For the fruit category, intake of fresh, frozen, canned, and dried fruits were reported.^ Results. Results showed that 90-95% of parents reported having vegetables and fruits available in the home. However, the only significant relationship between availability and intake was for fresh fruit and dried fruit. No associations were seen among the vegetable groups. Other vegetables (bell peppers, eggplant, tomatoes, onions, iceberg lettuce, asparagus) that were frozen, approached significance for availability on intake, however once adjusted for confounders the relationship was no longer present. Among soda, salty snacks, and sweet snacks the only significant relationship was seen for soda availability and intake. Salty snacks and sweet snacks presence in the home was not a predictor of increased frequency of intake.^ Conclusions. This research supported the hypothesis that availability of foods has an impact on intake for fresh fruits, dried fruits and soda. No associations were seen for vegetables, salty snacks and sweet snacks. Additionally, most of the parents reported having fruits and vegetables in the home, but reported intakes were not meeting the Dietary Guidelines for Americans recommendations. Strengths of the study included the large sample size taken from numerous HCDE Head Start Centers. Limitations included questionable reliability of participant’s responses, ability to generalize to other populations, and the use of secondary data rather than prospectively collected data.^
Resumo:
In Part One, the foundations of Bayesian inference are reviewed, and the technicalities of the Bayesian method are illustrated. Part Two applies the Bayesian meta-analysis program, the Confidence Profile Method (CPM), to clinical trial data and evaluates the merits of using Bayesian meta-analysis for overviews of clinical trials.^ The Bayesian method of meta-analysis produced similar results to the classical results because of the large sample size, along with the input of a non-preferential prior probability distribution. These results were anticipated through explanations in Part One of the mechanics of the Bayesian approach. ^
Resumo:
This study was designed to identify some of the factors related to patterns of physician visits to nursing home residents. The relationship of ten resident and organizational characteristics to patterns of physician visits was investigated through secondary analysis of data abstracted from the 1973-74 National Nursing Home Survey of the National Center for Health Statistics. The study sample was composed of 11,135 of the 19,013 nursing home residents who participated in the survey.^ The analytic results revealed that all ten variables had a statistically significant relationship to patterns of physician visits, mainly due to the large sample size. The degrees of association between the variables, measured by the Cramer's V statistic, ranged from moderate to very weak.^ Certification status of the nursing home under Medicare and/or Medicaid was shown to be most strongly related to patterns of physician visits, followed by primary source of payment for nursing home care, and residence prior to nursing home admission. Several variables thought to be related to patterns of physician visits were found to have a very weak relationship: age of the resident, marital status, length of stay, primary diagnosis, number of chronic conditions, activities of daily living status, and levels of care.^ In order to get a more precise picture of the relative influence of certification status and primary source of payment when the other variables were statistically controlled, these two variables were combined into a single variable. The results revealed that the combined effects of certification status and primary source of payment were sustained, regardless of differences in the residents' personal, utilization, and health status characteristics, and the levels of care that they received. The results also indicated that the five groups created by combining the two variables differed in patterns of physician visits. For example, private pay residents in intermediate care facilities (ICF's) and non-certified facilities were more likely to receive unscheduled visits than private pay residents in skilled nursing homes (SNH's), residents in SNH's supported by Medicare or Medicaid, and residents in ICF's supported by Medicaid. ^