96 resultados para Fire performance
Resumo:
Abstract The neo-liberal capitalist ideology has come under heavy fire with anecdotal evidence indicating a link between these same values and unethical behavior. Academic institutions reflect social values and act as socializing agents for the young. Can this explain the high and increasing rates of cheating that currently prevail in education? Our first chapter examines the question of whether self-enhancement values of power and açhievement, the individual level equivalent of neo-liberal capitalist values, predict positive attitudes towards cheating. Furthermore, we explore the mediating role of motivational factors. Results of four studies reveal that self-enhancement value endorsement predicts the adoption of performance-approach goals, a relationship mediated by introjected regulation, namely desire for social approval and that self-enhancement value endorsement also predicts the condoning of cheating, a relationship mediated by performance-approach goal adoption. However, self-transcendence values prescribed by a normatively salient source have the potential to reduce the link between self-enhancement value endorsément and attitudes towards cheating. Normative assessment constitutes a key tool used by academic institutions to socialize young people to accept the competitive, meritocratic nature of a sociéty driven by a neo-liberal capitalist ideology. As such, the manifest function of grades is to motivate students to work hard and to buy into the competing ethos. Does normative assessment fulfill these functions? Our second chapter explores the reward-intrinsic motivation question in the context of grading, arguably a high-stakes reward. In two experiments, the relative capacity of graded high performance as compared to the task autonomy experienced in an ungraded task to predict post-task intrinsic motivation is assessed. Results show that whilst the graded task performance predicts post-task appreciation, it fails to predict ongoing motivation. However, perceived autonomy experienced in non-graded condition, predicts both post-task appreciation and ongoing motivation. Our third chapter asks whether normative assessment inspires the spirit of competition in students. Results of three experimental studies reveal that expectation of a grade for a task, compared to no grade, induces greater adoption of performance-avoidance, but not performance-approach, goals. Experiment 3 provides an explanatory mechanism for this, showing that reduced autonomous motivation experienced in previous graded tasks mediates the relationship between grading and adoption of performance avoidance goals in a subsequent task. The above results, when combined, provide evidence as to the deleterious effects of self enhancement values and the associated practice of normative assessment in school on student motivation, goals and ethics. We conclude by using value and motivation theory to explore solutions to this problem.
Resumo:
Several studies (on an inclined platform or with special shoes) have reported improved jump performance when the ankle was in a dorsiflexion (DF) position. The present study aims to test whether shoes inducing moderate DF modify vertical jump performance and energy cost. Twenty-one young, healthy female subjects (30 +/- 6 yr, 58 +/- 6 kg, O2max 45 +/- 3 mLxkg-1xmin-1, mean +/- SD) participated in the study. Jump performance was tested with subjects either wearing 4 degrees DF or standard (S) shoes. The jump tests (performed on a force platform) consisted of squat jump (SJ), countermovement jump (CMJ), and continuous jumps (CJ) during 15 seconds. Measured parameters were jump height, speed at take off, and maximal and average power. Oxygen uptake was measured on a treadmill while subjects ran at 95% of the anaerobic threshold during a 7-minute steady-state period. As compared with S shoes, DF shoes significantly improved the height of SJ (31 +/- 4 cm vs. 34 +/- 4 cm, p = 0.0001), CMJ (32 +/- 4 cm vs. 34 +/- 4 cm, p = 0.0004), and CJ (17.5 +/- 4.2 cm vs. 22.0 +/- 6.0 cm, p = 0.0001). Speed at take off was also significantly higher. Mean power significantly increased in SJ and CJ but not in CMJ. Oxygen uptake was not different between conditions (p = 0.40). Dorsiflexion shoes induce a significant increase in jump performance. These results are in accordance with the concept that a DF of the ankle may induce an increase of the length and strength of the triceps surae (higher torque). However, wearing DF shoes did not require more energy during running. Dorsiflexion shoes could be used to increase jump performance in several sports such as volleyball in which jump height is essential.
Resumo:
Many firms around the world are managed and partially owned by entrepreneurs. These entrepreneurs hold under diversified portfolios and, therefore, bear idiosyncratic risk in addition to systematic risk. To compensate the additional risk borne, they extract private benefits. In this paper, we analyse how an entrepreneur's overconfidence affects the market performance of the firm, through the channel of private benefits. We show that two dimensions of overconfidence, namely overestimation of future cash-flows and underestimation of idiosyncratic risk (called miscalibration), have opposite effects on the private benefits extracted by the entrepreneur. As a consequence, firms managed and partially owned by overconfident entrepreneurs can deliver overperformance or underperformance, depending on the prevalence of overestimation or miscalibration of the beliefs of the entrepreneur.
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ECG criteria for left ventricular hypertrophy (LVH) have been almost exclusively elaborated and calibrated in white populations. Because several interethnic differences in ECG characteristics have been found, the applicability of these criteria to African individuals remains to be demonstrated. We therefore investigated the performance of classic ECG criteria for LVH detection in an African population. Digitized 12-lead ECG tracings were obtained from 334 African individuals randomly selected from the general population of the Republic of Seychelles (Indian Ocean). Left ventricular mass was calculated with M-mode echocardiography and indexed to body height. LVH was defined by taking the 95th percentile of body height-indexed LVM values in a reference subgroup. In the entire study sample, 16 men and 15 women (prevalence 9.3%) were finally declared to have LVH, of whom 9 were of the reference subgroup. Sensitivity, specificity, accuracy, and positive and negative predictive values for LVH were calculated for 9 classic ECG criteria, and receiver operating characteristic curves were computed. We also generated a new composite time-voltage criterion with stepwise multiple linear regression: weighted time-voltage criterion=(0.2366R(aVL)+0.0551R(V5)+0.0785S(V3)+ 0.2993T(V1))xQRS duration. The Sokolow-Lyon criterion reached the highest sensitivity (61%) and the R(aVL) voltage criterion reached the highest specificity (97%) when evaluated at their traditional partition value. However, at a fixed specificity of 95%, the sensitivity of these 10 criteria ranged from 16% to 32%. Best accuracy was obtained with the R(aVL) voltage criterion and the new composite time-voltage criterion (89% for both). Positive and negative predictive values varied considerably depending on the concomitant presence of 3 clinical risk factors for LVH (hypertension, age >/=50 years, overweight). Median positive and negative predictive values of the 10 ECG criteria were 15% and 95%, respectively, for subjects with none or 1 of these risk factors compared with 63% and 76% for subjects with all of them. In conclusion, the performance of classic ECG criteria for LVH detection was largely disparate and appeared to be lower in this population of East African origin than in white subjects. A newly generated composite time-voltage criterion might provide improved performance. The predictive value of ECG criteria for LVH was considerably enhanced with the integration of information on concomitant clinical risk factors for LVH.
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Etant données la complexité et la redondance des réseaux de gènes influençant de nombreux phénotypes, l'étude des rares cas d'un locus unique ayant des effets importants sur de nombreux phénotypes peut fournir des informations cruciales sur l'évolution des traits complexes. Nous avons séquencé le génome de la fourmi de feu Solenopsis invicta pour étudier comment l'expression des gènes détermine les effets majeurs et étendus de deux loci uniques sur le phénotype. Le premier locus concerne la détermination du sexe par le modèle des allèles complémentaires. Ce locus est connu pour déterminer le sexe chez tous les hyménoptères mais n'a été caractérisé que chez les abeilles. Les hétérozygotes pour ce locus se développent en reines diploïdes (ou ouvrières stériles) alors que les homozygotes se développent en mâles diploïdes incapables de produire du sperme et les hémizygotes en mâles haploïdes fertiles. Nous avons comparé l'expression des gènes entre les reines et les deux types de mâles au stade pupe, ainsi que 1 et 11 jours après l'émergence. Nous avons trouvé un changement prononcé de l'expression des gènes chez les mâles diploïdes, passant de très proche de celle des reines au stade pupe à identique aux mâles haploïdes 11 jours après l'émergence. Cela signifie que les mâles diploïdes sont condamnés à être stériles parce que les effets après émergence du locus de détermination du sexe ne per¬mettent pas d'effacer les effets de la ploïdie sur l'expression des gènes pendant le stade pupe, quand la spermatogénèse prend place. Le second locus aux effets majeurs que nous avons étudié est le supergène dit "green beard", qui consiste en 616 gènes couvrant 55% d'un chromosome (13 Mb) et est caractérisé par une absence de recombinaison entre les deux variants du supergène : "Social B" et "Social b" (SB et Sb). Au travers de l'effet "green beard", par lequel les ouvrières avec le supergène Sb discriminent favorablement les reines qui partagent ce supergène de façon perceptible, le génotype des reines fondatrices au niveau de ce supergène détermine l'organisation de la colonie : soit elle contient une seule reine SB/SB, soit plusieurs reines SB/Sb. Nous avons montré que le chromosome Sb a évolué comme le chromosome Y, accumulant probablement des allèles favorables dans des colonies avec plusieurs reines mais défavorables dans des colonies avec une seule reine (cf. gènes sexuellement antagonistes), ainsi que des transposons et des séquences répéti¬tives. Nous avons également montré que le polymorphisme du supergène cause de grandes différences d'expression chez les ouvrières et particulièrement les reines mais pas chez les mâles. Pour comprendre comment le polymorphisme du supergène chez les reines peut affecter l'organisation de la colonie, nous avons comparé l'expression entre les génotypes SB/SB et SB/Sb chez des reines vierges (1 et 11 jours) et des reines matures. Nous avons montré que les reines SB/SB sur-régulent des gènes impliqués dans la reproduction, expli-quant pourquoi elle grandissent plus rapidement et peuvent fonder des colonies de façon indépendante, tandis que les reines SB/Sb (qui ne peuvent fonder une nouvelle colonie) sur-régulent des gènes de signalement chimique qui affectent l'organisation des colonies par l'effet "green beard". - Given the complexity and redundancy of the gene networks that underlie many pheno- types, the study of rare cases of a single locus having major effects on many phenotypes can give powerful insights into the evolution of complex traits. We sequenced the genome of Solenopsis invicta fire ants to study how gene expression mediates the widespread major effects of two single loci on phenotype. The first is the complementary sex-determining locus, which is known to exist in most Hymenoptera despite being characterized only for honeybees. Heterozygotes at this locus become diploid queens (or sterile workers), homozy¬gotes become aspermic diploid males, and hemizygotes become fertile haploid males. We compared gene expression between queens and both types of males in pupae and 1 and 11 days after eclosion. We found a pronounced shift in gene expression in diploid males, from being nearly identical to queens as pupae to identical to haploid males 11 days after eclosion. This means that diploid males are condemned to sterility because the overriding effects of the sex locus after eclosion cannot undo the ploidy effects on expression during the pupal stage, when spermatogenesis must be completed. The second locus with major ef¬fects that we studied was the so-called "green beard" supergene, which consists of 616 genes encompassing 55% of one chromosome (13 Mb), without recombination between the two variants "Social B" and "Social b" (SB and Sb) supergene. Through the green beard effect, i.e. workers with the Sb supergene discriminating in favor of queens who perceptibly share this supergene, the founding queen's genotype at the supergene determines colony organi¬zation: either headed by a single SB/SB queen or many SB/Sb queens. We show that the Sb chromosome evolved like a Y-chromosome, probably accumulating alleles beneficial in multi-queen colonies but disadvantageous in single-queen colonies (cf. sexually antagonistic genes), as well as transposons and repetitive sequences. We also show that the polymor¬phism of the supergene causes widespread expression differences in workers and especially queens but not in males. To understand how the polymorphism at the supergene in queen can transform colony organization, we compared the expression between SB/SB and SB/Sb virgin queens (1 and 11 days) and mother queens. We show that SB/SB queens up-regulate genes involved in reproduction, explaining why they mature faster and can found colonies independently, while SB/Sb queens (which cannot found colonies) up-regulate chemical signaling genes that can transform colonies through the green beard effect.
Resumo:
BACKGROUND: Surgeons' personalities have been described as different from those of the general population, but this was based on small descriptive studies limited by the choice of evaluation instrument. Furthermore, although the importance of the human factor in team performance has been recognized, the effect of personality traits on technical performance is unknown. This study aimed to compare surgical residents' personality traits with those of the general population and to evaluate whether an association exists between their personality traits and technical performance using a virtual reality (VR) laparoscopy simulator. METHODS: In this study, 95 participants (54 residents with basic, 29 with intermediate laparoscopic experience, and 12 students) underwent personality assessment using the NEO-Five Factor Inventory and performed five VR tasks of the Lap Mentor? basic tasks module. The residents' personality traits were compared with those of the general population, and the association between VR performance and personality traits was investigated. RESULTS: Surgical residents showed personality traits different from those of the general population, demonstrating lower neuroticism, higher extraversion and conscientiousness, and male residents showed greater openness. In the multivariable analysis, adjusted for gender and surgical experience, none of the personality traits was found to be an independent predictor of technical performance. CONCLUSIONS: Surgical residents present distinct personality traits that differ from those of the general population. These traits were not found to be associated with technical performance in a virtual environment. The traits may, however, play an important role in team performance, which in turn is highly relevant for optimal surgical performance.
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The purpose of this study was to examine the relationship between skeletal muscle monocarboxylate transporters 1 and 4 (MCT1 and MCT4) expression, skeletal muscle oxidative capacity and endurance performance in trained cyclists. Ten well-trained cyclists (mean +/- SD; age 24.4 +/- 2.8 years, body mass 73.2 +/- 8.3 kg, VO(2max) 58 +/- 7 ml kg(-1) min(-1)) completed three endurance performance tasks [incremental exercise test to exhaustion, 2 and 10 min time trial (TT)]. In addition, a muscle biopsy sample from the vastus lateralis muscle was analysed for MCT1 and MCT4 expression levels together with the activity of citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HAD). There was a tendency for VO(2max) and peak power output obtained in the incremental exercise test to be correlated with MCT1 (r = -0.71 to -0.74; P < 0.06), but not MCT4. The average power output (P (average)) in the 2 min TT was significantly correlated with MCT4 (r = -0.74; P < 0.05) and HAD (r = -0.92; P < 0.01). The P (average) in the 10 min TT was only correlated with CS activity (r = 0.68; P < 0.05). These results indicate the relationship between MCT1 and MCT4 as well as cycle TT performance may be influenced by the length and intensity of the task.
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A selective and sensitive method was developed for the simultaneous quantification of seven typical antipsychotic drugs (cis-chlorprothixene, flupentixol, haloperidol, levomepromazine, pipamperone, promazine and zuclopenthixol) in human plasma. Ultra-high performance liquid chromatography (UHPLC) was used for complete separation of the compounds in less than 4.5min on an Acquity UPLC BEH C18 column (2.1mm×50mm; 1.7μm), with a gradient elution of ammonium formate buffer pH 4.0 and acetonitrile at a flow rate of 400μl/min. Detection was performed on a tandem quadrupole mass spectrometer (MS/MS) equipped with an electrospray ionization interface. A simple protein precipitation procedure with acetonitrile was used for sample preparation. Thanks to the use of stable isotope-labeled internal standards for all analytes, internal standard-normalized matrix effects were in the range of 92-108%. The method was fully validated to cover large concentration ranges of 0.2-90ng/ml for haloperidol, 0.5-90ng/ml for flupentixol, 1-450ng/ml for levomepromazine, promazine and zuclopenthixol and 2-900ng/ml for cis-chlorprothixene and pipamperone. Trueness (89.1-114.8%), repeatability (1.8-9.9%), intermediate precision (1.9-16.3%) and accuracy profiles (<30%) were in accordance with the latest international recommendations. The method was successfully used in our laboratory for routine quantification of more than 500 patient plasma samples for therapeutic drug monitoring. To the best of our knowledge, this is the first UHPLC-MS/MS method for the quantification of the studied drugs with a sample preparation based on protein precipitation.
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BACKGROUND: The diagnosis of hypertension in children is difficult because of the multiple sex-, age-, and height-specific thresholds to define elevated blood pressure (BP). Blood pressure-to-height ratio (BPHR) has been proposed to facilitate the identification of elevated BP in children. OBJECTIVE: We assessed the performance of BPHR at a single screening visit to identify children with hypertension that is sustained elevated BP. METHOD: In a school-based study conducted in Switzerland, BP was measured at up to three visits in 5207 children. Children had hypertension if BP was elevated at the three visits. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) for the identification of hypertension were assessed for different thresholds of BPHR. The ability of BPHR at a single screening visit to discriminate children with and without hypertension was evaluated with receiver operating characteristic (ROC) curve analyses. RESULTS: The prevalence of systolic/diastolic hypertension was 2.2%. Systolic BPHR had a better performance to identify hypertension compared with diastolic BPHR (area under the ROC curve: 0.95 vs. 0.84). The highest performance was obtained with a systolic BPHR threshold set at 0.80 mmHg/cm (sensitivity: 98%; specificity: 85%; PPV: 12%; and NPV: 100%) and a diastolic BPHR threshold set at 0.45 mmHg/cm (sensitivity: 79%; specificity: 70%; PPV: 5%; and NPV: 99%). The PPV was higher among tall or overweight children. CONCLUSION: BPHR at a single screening visit had a high performance to identify hypertension in children, although the low prevalence of hypertension led to a low PPV.
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OBJECTIVE: Transthoracic echocardiography (TTE) has been used clinically to disobstruct venous drainage cannula and to optimise placement of venous cannulae in the vena cava but it has never been used to evaluate performance capabilities. Also, little progress has been made in venous cannula design in order to optimise venous return to the heart lung machine. We designed a self-expandable Smartcanula (SC) and analysed its performance capability using echocardiography. METHODS: An epicardial echocardiography probe was placed over the SC or control cannula (CTRL) and a Doppler image was obtained. Mean (V(m)) and maximum (V(max)) velocities, flow and diameter were obtained. Also, pressure drop (DeltaP(CPB)) was obtained between the central venous pressure and inlet to venous reservoir. LDH and Free Hb were also compared in 30 patients. Comparison was made between the two groups using the student's t-test with statistical significance established when p<0.05. RESULTS: Age for the SC and CC groups were 61.6+/-17.6 years and 64.6+/-13.1 years, respectively. Weight was 70.3+/-11.6 kg and 72.8+/-14.4 kg, respectively. BSA was 1.80+/-0.2 m(2) and 1.82+/-0.2 m(2), respectively. CPB times were 114+/-53 min and 108+/-44 min, respectively. Cross-clamp time was 59+/-15 min and 76+/-29 min, respectively (p=NS). Free-Hb was 568+/-142 U/l versus 549+/-271 U/l post-CPB for the SC and CC, respectively (p=NS). LDH was 335+/-73 mg/l versus 354+/-116 mg/l for the SC and CC, respectively (p=NS). V(m) was 89+/-10 cm/s (SC) versus 63+/-3 cm/s (CC), V(max) was 139+/-23 cm/s (SC) versus 93+/-11 cm/s (CC) (both p<0.01). DeltaP(CPB) was 30+/-10 mmHg (SC) versus 43+/-13 mmHg (CC) (p<0.05). A Bland-Altman test showed good agreement between the two devices used concerning flow rate calculations between CPB and TTE (bias 300 ml+/-700 ml standard deviation). CONCLUSIONS: This novel Smartcanula design, due to its self-expanding principle, provides superior flow characteristics compared to classic two stage venous cannula used for adult CPB surgery. No detrimental effects were observed concerning blood damage. Echocardiography was effective in analysing venous cannula performance and velocity patterns.
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We examine the relationship between structural social capital, resource assembly, and firm performance of entrepreneurs in Africa. We posit that social capital primarily composed of kinship or family ties helps the entrepreneur to raise resources, but it does so at a cost. Using data drawn from small firms in Kampala, Uganda, we explore how shared identity among the entrepreneur's social network moderates this relationship. A large network contributed a higher quantity of resources raised, but at a higher cost when shared identity was high. We discuss the implications of these findings for the role of family ties and social capital in resource assembly, with an emphasis on developing economies.