Relationship between oviposition preference and offspring performance in Australian Helicoverpa armigera (Hubner) (Lepidoptera : Noctuidae)

We investigated the oviposition preference and larval performance of Helicoverpa armigera under laboratory conditions to determine if the oviposition preference of individual females on maize, cowpea and cotton correlates with offspring performance on the leaves of the same host plants. The host-plant preference hierarchy of females did not correlate with their offspring performance. Female moths chose host plants that contributed less to their offspring fitness. Plant effects accounted for the largest amount of variation in offspring performance, while the effects of female (family) was low. The offspring of most females (80%, n = 10) were broadly similar, but 20% (two out of 10), showed marked difference in their offspring performance across the host-plant species. Similarly, there was no relation between larval feeding preference and performance. However, like most laboratory experiments, our experi-mental design does not allow the evaluation of ecological factors (for example, natural enemies, host abundance, etc.) that can play an important role in larval performance in the field. Overall, the results highlight the importance of carrying out preference performance analysis on the individual or family level, rather than pooling individuals to obtain average population data.

The JK three-product cyclone - performance and potential applications

In spite of their wide application in comminution circuits, hydrocyclones have at least one significant disadvantage in that their operation inherently tends to return the fine denser liberated minerals to the grinding mill. This results in unnecessary overgrinding which adds to the milling cost and can adversely affect the efficiency of downstream processes. In an attempt to solve this problem, a three-product cyclone has been developed at the Julius Kruttschnitt Mineral Research Centre (JKMRC) to generate a second overflow in which the fine dense liberated minerals can be selectively concentrated for further treatment. In this paper, the design and operation of the three-product cyclone are described. The influence of the length of the second vortex finder on the performance of a 150-mm unit treating a mixture of magnetite and silica is investigated. Conventional cyclone tests were also conducted under similar conditions. Using the operational performance data of the three-product and conventional cyclones, it is shown that by optimising the length of the second vortex finder, the amount of fine dense mineral particles that reports to the three-product cyclone underflow can be reduced. In addition, the three-product cyclone can be used to generate middlings stream that may be more suitable for flash flotation than the conventional cyclone underflow, or alternatively, could be classified with a microscreen to separate the valuables from the gangue. At the same time, a fines stream having similar properties to those of the conventional overflow can be obtained. Hence, if the middlings stream was used as feed for flash flotation or microscreening, the fines stream could be used in lieu of the conventional overflow without compromising the feed requirements for the conventional flotation circuit. Some of the other potential applications of the new cyclone are described. (C) 2003 Elsevier Science B.V. All rights reserved.

Cognitive style factors affecting database query performance

As end-user computing becomes more pervasive, an organization's success increasingly depends on the ability of end-users, usually in managerial positions, to extract appropriate data from both internal and external sources. Many of these data sources include or are derived from the organization's accounting information systems. Managerial end-users with different personal characteristics and approaches are likely to compose queries of differing levels of accuracy when searching the data contained within these accounting information systems. This research investigates how cognitive style elements of personality influence managerial end-user performance in database querying tasks. A laboratory experiment was conducted in which participants generated queries to retrieve information from an accounting information system to satisfy typical information requirements. The experiment investigated the influence of personality on the accuracy of queries of varying degrees of complexity. Relying on the Myers–Briggs personality instrument, results show that perceiving individuals (as opposed to judging individuals) who rely on intuition (as opposed to sensing) composed queries more accurately. As expected, query complexity and academic performance also explain the success of data extraction tasks.

An electromyographic analysis of the deep cervical flexor muscles in performance of craniocervical flexion

Background and Purpose. This study evaluated an electromyographic technique for the measurement of muscle activity of the deep cervical flexor (DCF) muscles. Electromyographic signals were detected from the DCF, sternocleidomastoid (SCM), and anterior scalene (AS) muscles during performance of the craniocervical flexion (CCF) test, which involves performing 5 stages of increasing craniocervical flexion range of motion-the anatomical action of the DCF muscles. Subjects. Ten volunteers without known pathology or impairment participated in this study. Methods. Root-mean-square (RMS) values were calculated for the DCF, SCM, and AS muscles during performance of the CCF test. Myoelectric signals were recorded from the DCF muscles using bipolar electrodes placed over the posterior oropharyngeal wall. Reliability estimates of normalized RMS values were obtained by evaluating intraclass correlation coefficients and the normalized standard error of the mean (SEM). Results. A linear relationship was evident between the amplitude of DCF muscle activity and the incremental stages of the CCF test (F=239.04, df=36, P<.0001). Normalized SEMs in the range 6.7% to 10.3% were obtained for the normalized RMS values for the DCF muscles, providing evidence of reliability for these variables. Discussion and Conclusion. This approach for obtaining a direct measure of the DCF muscles, which differs from those previously used, may be useful for the examination of these muscles in future electromyographic applications.

Effect of type of grain and oil supplement on the performance, blood lipoproteins, egg cholesterol and fatty ccids of laying hens

The effects of type of grain (wheat vs. sorghum) and oil supplement/kg diet [0, 20g olive oil (OL), 20g safflower oil (SO), 10 g OL plus 10 g SO (OLSO)], over a 12-week period on the performance, plasma and lipoproteins lipids [cholesterol (C), triglycerides (TG), phospholipid (P)], and yolk C and fatty acids concentrations of laying hens were studied. Hens fed on the sorghum diet had significantly (P

Do expertise and the degree of perception-action coupling affect natural anticipatory performance?

Two experiments using a temporal occlusion paradigm (the first with expert and novice participants and the second with participants of intermediate skill) were conducted to examine the capability of tennis players to predict the direction of an opponent's service in situ. In both experiments two different response conditions, reflecting differing degrees of perception-action coupling, were employed. In a coupled condition players were required to make a movement-based response identical to that which they would use to hit a return of service in a game situation, whereas in an uncoupled condition a verbal prediction of service direction was required. Experiment 1 provided clear evidence of superior prediction accuracy under the coupled response condition when ball flight was available, plus some limited evidence to suggest that superior prediction accuracy under uncoupled response conditions might hold true if only advance (pre-contact) information was available. Experiment 2 showed the former finding to be a robust one, but was unable to reveal any support for the latter. Experiment 1 also revealed that expert superiority is more apparent for predictions made under natural (coupled) than uncoupled response-mode conditions. Collectively, these findings suggest that different perceptual processes may be in operation in anticipatory tasks which depend on skill level, the type of information presented, and degree of perception-action coupling inherent in the task requirements.

Sustained swimming performance in crocodiles (Crocodylus porosus): Effects of body size and temperature

We examined effects of body size and temperature on swimming performance in juvenile estuarine crocodiles, Crocodylus porosus, over the size range of 30-110 cm total body length. Swimming performance, expressed as maximum sustainable swimming speed, was measured in a temperature- and flow-controlled swimming flume. Absolute sustainable swimming speed increased with body length, but length-specific swimming performance decreased as body length increased. Sustained swimming speed increased with temperature between 15degreesC and 23degreesC, remained constant between 23degrees and 33degreesC, and decreased as temperature rose above 33degreesC. Q(10)-values of swimming speed were 2.60 (+/- 0.091 SE) between 18degreesC and 23degreesC, and there were no differences in Q(10) between crocodiles of different sizes. The broad plateau of thermal independence in swimming speed observed in C. porosus may be of adaptive significance by allowing dispersal of juvenile animals at suboptimal body temperatures.

Reproducibility of a laboratory-based 40-km cycle time-trial on a stationary wind-trainer in highly trained cyclists

The purpose of the present study was to examine the reproducibility of laboratory-based 40-km cycle time-trial performance on a stationary wind-trainer. Each week, for three consecutive weeks, and on different days, forty-three highly trained male cyclists ((x) over bar +/- SD; age = 25 +/- 6 y; mass = 75 +/- 7 kg; peak oxygen uptake [(V) over dot O-2 peak] = 64.8 +/- 5.2 ml x kg(-1) x min(-1)) performed: 1) a (V) over dot O-2 peak test, and 2) a 40-km time-trial on their own racing bicycle mounted to a stationary wind-trainer (Cateye - Cyclosimulator). Data from all tests were compared using a one-way analysis of variance. Performance on the second and third 40-km time-trials were highly related (r = 0.96; p < 0.001), not significantly different (57:21 +/- 2:57 vs. 57:12 +/- 3:14 min:s), and displayed a low coefficient of variation (CV) = 0.9 +/- 0.7%. Although the first 40-km time-trial (58:43 +/- 3:17min:s) was not significantly different from the second and third tests (p = 0.06), inclusion of the first test in the assessment of reliability increased within-subject CV to 3.0 +/- 2.9%. 40-km time-trial speed (km x h(-1)) was significantly (p < 0.001) related to peak power output (W; r = 0.75), (V) over dot O-2 peak (1 x min(-1); r = 0.53), and the second ventilatory turnpoint (1 x min(-1); r = 0.68) measured during the progressive exercise tests. These data demonstrate that the assessment of 40-km cycle time-trial performance in well-trained endurance cyclists on a stationary wind-trainer is reproducible, provided the athletes perform a familiarization trial.

Physiological responses to repeated bouts of high-intensity ultraendurance cycling - a field study case report

The present study aimed to 1) examine the relationship between laboratory-based measures and high-intensity ultraendurance (HIU) performance during an intermittent 24-h relay ultraendurance mountain bike race (similar to20 min cycling, similar to60min recovery), and 2) examine physiological and performance based changes throughout the HIU event. Prior to the HIU event, four highly-trained male cyclists (age = 24.0 +/- 2.1 yr; mass = 75.0 +/- 2.7 kg; (V)over dot O-2peak = 70 +/- 3 ml.kg(-1).min(-1)) performed 1) a progressive exercise test to determine peak Volume of oxygen uptake ((V)over dot O-2peak), peak power output (PPO), and ventilatory threshold (T-vent), 2) time-to-fatigue tests at 100% (TF100) and 150% of PPO (TF150), and 3) a laboratory simulated 40-km time trial (TT40). Blood lactate (Lac(-)), haematocrit and haemoglobin were measured at 6-h intervals throughout the HIU event, while heart rate (HR) was recorded continuously. Intermittent HIU performance, performance HR, recovery HR, and Lac declined (P < 0.05), while plasma volume expanded (P < 0.05) during the HIU event. TF100 was related to the decline in lap time (r = -0.96; P < 0.05), and a trend (P = 0.081) was found between TF150 and average intermittent HIU speed (r = 0.92). However, other measures (V)over dot O-2peak, PPO, T-vent, and TT40) were not related to HIU performance. Measures of high-intensity endurance performance (TF100, TF150) were better predictors of intermittent HIU performance than traditional laboratory-based measures of aerobic capacity.

Relationship of ventricular longitudinal function to contractile reserve in patients with mitral regurgitation

Background Latent left ventricular (LV) dysfunction in patients with valvular or myocardial disease may be identified by loss of contractile reserve (CR) at exercise echocardiography. Contraction in the LV longitudinal axis may be more sensitive than radial contraction to minor disturbances of LV function. We sought to determine whether tissue Doppler measurement of longitudinal function could be used to identify CR. Methods Exercise echocardiography was performed in 86 patients (20 women, age 53 +/- 18 years), 72 with asymptomatic or minimally symptomatic mitral regurgitation, and 14 normal controls. Pulsed-wave tissue Doppler imaging (DTI) was used to measure maximum annular systolic velocity at rest and stress. Inducible ischemia was excluded by analysis of wall motion by an experienced observer. CR was defined by greater than or equal to5% improvement of stress compared with rest ejection fraction (EF). Exercise capacity was assessed from expired gas analysis. Results CR was present in 34 patients with mitral regurgitation (47%); peak EF in patients with and without CR was 74% +/- 11% versus 54% +/- 15% (P

Effect of lifter design on drying performance in rotary dryers

Lifter use in dryers improves mass transfer by increasing the amount of surface area available for transfer and also by increasing the velocity of gas over the particle surface. An even cross-sectional distribution of particles in a dryer improves the efficiency of operation by ensuring that evaporation from falling particles is taking place for the maximum fraction of the rotation period of the drier. Studies on lifter design to improve the cross-sectional particle distribution were performed on angled lifters. A single lifter was used and the mass-transfer rate examined as a function of angular lifter displacement. Analysis of the mass transfer characteristics of single lifters allowed performance comparisons and recommendations for lifter design.