Reliability and validity of physical fitness field tests for adults aged 55 to 70 years

The aim of this study was to examine the reliability and validity of field tests for assessing physical function in mid-aged and young-old people (55–70 y). Tests were selected that required minimal space and equipment and could be implemented in multiple field settings such as a general practitioner's office. Nineteen participants completed 2 field and 1 laboratory testing sessions. Intra-class correlations showed good reliability for the tests of upper body strength (lift and reach, R= .66), lower body strength (sit to stand, R= .80) and functional capacity (Canadian Step Test, R= .92), but not for leg power (single timed chair rise, R= .28). There was also good reliability for the balance test during 3 stances: parallel (94.7% agreement), semi-tandem (73.7%), and tandem (52.6%). Comparison of field test results with objective laboratory measures found good validity for the sit to stand (cf 1RM leg press, Pearson r= .68, p< .05), and for the step test (cf PWC140, r= −.60, p< .001), but not for the lift and reach (cf 1RM bench press, r= .43, p> .05), balance (r= −.13, −.18, .23) and rate of force development tests (r= −.28). It was concluded that the lower body strength and cardiovascular function tests were appropriate for use in field settings with mid-aged and young-old adults.

Control of vector-borne disease by genetic manipulation of insect populations: technological requirements and research priorities

The possibility of controlling vector-borne disease through the development and release of transgenic insect vectors has recently gained popular support and is being actively pursued by a number of research laboratories around the world. Several technical problems must be solved before such a strategy could be implemented: genes encoding refractory traits (traits that render the insect unable to transmit the pathogen) must be identified, a transformation system for important vector species has to be developed, and a strategy to spread the refractory trait into natural vector populations must be designed. Recent advances in this field of research make it seem likely that this technology will be available in the near future. In this paper we review recent progress in this area as well as argue that care should be taken in selecting the most appropriate disease system with which to first attempt this form of intervention. Much attention is currently being given to the application of this technology to the control of malaria, transmitted by Anopheles gambiae in Africa. While malaria is undoubtedly the most important vector-borne disease in the world and its control should remain an important goal, we maintain that the complex epidemiology of malaria together with the intense transmission rates in Africa may make it unsuitable for the first application of this technology. Diseases such as African trypanosomiasis, transmitted by the tsetse fly, or unstable malaria in India may provide more appropriate initial targets to evaluate the potential of this form of intervention.

The critical power function is dependent on the duration of the predictive exercise tests chosen

The linear relationship between work accomplished (W-lim) and time to exhaustion (t(lim)) can be described by the equation: W-lim = a + CP.t(lim). Critical power (CP) is the slope of this line and is thought to represent a maximum rate of ATP synthesis without exhaustion, presumably an inherent characteristic of the aerobic energy system. The present investigation determined whether the choice of predictive tests would elicit significant differences in the estimated CP. Ten female physical education students completed, in random order and on consecutive days, five art-out predictive tests at preselected constant-power outputs. Predictive tests were performed on an electrically-braked cycle ergometer and power loadings were individually chosen so as to induce fatigue within approximately 1-10 mins. CP was derived by fitting the linear W-lim-t(lim) regression and calculated three ways: 1) using the first, third and fifth W-lim-t(lim) coordinates (I-135), 2) using coordinates from the three highest power outputs (I-123; mean t(lim) = 68-193 s) and 3) using coordinates from the lowest power outputs (I-345; mean t(lim) = 193-485 s). Repeated measures ANOVA revealed that CPI123 (201.0 +/- 37.9W) > CPI135 (176.1 +/- 27.6W) > CPI345 (164.0 +/- 22.8W) (P < 0.05). When the three sets of data were used to fit the hyperbolic Power-t(lim) regression, statistically significant differences between each CP were also found (P < 0.05). The shorter the predictive trials, the greater the slope of the W-lim-t(lim) regression; possibly because of the greater influence of 'aerobic inertia' on these trials. This may explain why CP has failed to represent a maximal, sustainable work rate. The present findings suggest that if CP is to represent the highest power output that an individual can maintain for a very long time without fatigue then CP should be calculated over a range of predictive tests in which the influence of aerobic inertia is minimised.

Predicting sprint running times from isokinetic and squat lift tests: A regression analysis

This study examined the relationship between isokinetic hip extensor/hip flexor strength, 1-RM squat strength, and sprint running performance for both a sprint-trained and non-sprint-trained group. Eleven male sprinters and 8 male controls volunteered for the study. On the same day subjects ran 20-m sprints from both a stationary start and with a 50-m acceleration distance, completed isokinetic hip extension/flexion exercises at 1.05, 4.74, and 8.42 rad.s(-1), and had their squat strength estimated. Stepwise multiple regression analysis showed that equations for predicting both 20-m maximum velocity nm time and 20-m acceleration time may be calculated with an error of less than 0.05 sec using only isokinetic and squat strength data. However, a single regression equation for predicting both 20-m acceleration and maximum velocity run times from isokinetic or squat tests was not found. The regression analysis indicated that hip flexor strength at all test velocities was a better predictor of sprint running performance than hip extensor strength.

Determination of Ralstonia (Pseudomonas) solanacearum rDNA subgroups by PCR tests

Rapid and sensitive polymerase chain reaction (PCR) methods ape described for determination of the two 16 S rDNA subgroups of Ralstonia solanacearum, the causal agent of bacterial wilt. A third subgroup consisting of Indonesian R. solanacearum isolates belonging to Division II, the blood disease bacterium and Pseudomonas syzygii can also be identified. Primers were designed to sequences within R, solanacearum 16 S rDNA (equivalent to Escherichia coli 16 S rDNA positions 74-97, 455-475, 1454-1474), and the internal transcribed spacer region between the 16 S and 23 S rDNA genes. Different combinations of forward and reverse primers allowed selective PCR amplification of (a) R. solanacearum Division I (biovars 3, 4 and 5), (b) Division TI (biovars 1, N2, and 2) including the blood disease bacterium and P. syzygii, or (c) amplification of Division II only except for five biovar 1, 2 or N2 isolates of R. solanacearum from Indonesia, P. syzygii and the BDB. A total of 104 R. solanacearum, 14 blood disease bacterium and 10 P. syzygii isolates were tested. Simultaneous detection of species and subdivision was achieved by designing a multiplex PCR test in which a 288-base pair (bp) band is produced by all R. solanacearum isolates, and an additional 409-bp band in Division I strains.

Swapping space for time and unfair tests of ecological models

Testing ecological models for management is an increasingly important part of the maturation of ecology as an applied science. Consequently, we need to work at applying fair tests of models with adequate data. We demonstrate that a recent test of a discrete time, stochastic model was biased towards falsifying the predictions. If the model was a perfect description of reality, the test falsified the predictions 84% of the time. We introduce an alternative testing procedure for stochastic models, and show that it falsifies the predictions only 5% of the time when the model is a perfect description of reality. The example is used as a point of departure to discuss some of the philosophical aspects of model testing.

A technological and organisational explanation for the size distribution of firms

This paper combines insights from the literature on the economics of organisation with traditional models of market structure to construct a theory of equilibrium firm size heterogeneity under the assumption of a homogenous product industry. It is possible that configurations consisting entirely of small firms (run by entrepreneurs with limited attention) and with larger firms (using managerial techniques to substitute away these limits to allow increasing returns technologies to become profitable) can arise in equilibrium. However, there also exist equilibrium configurations with the co-existence of large and small firms. The efficiency properties of these respective equilibria are discussed. Finally, the implications of an expanding market size are considered.

Investigating the influence of achievement on self-concept using an intra-class design and a comparison of the PASS and SDQ-1 self-concept tests

Background. The formation and measurement of self-concept were the foci of this research. Aims. The study aimed to investigate the influence of achievement on academic self-concept and to compare the Perception of Ability Scale for Students (PASS, Boersma & Chapman, 1992) with the Self-Description Questionnaire-1 (SDQ-1, Marsh, 1988). Sample. The participants were 479 grade 5 (mean age 126.6 months) coeducational Australian students, located in 18 schools. Method. An intra-class research design was used to investigate the influence of frame-of-reference on self-concept development. Results. As students' academic scores rose above their class mean their self-concepts increased and as students' academic scores fell below their class mean their self-concepts decreased. Students' difference from class mean predicted their self-concept scores. This finding was consistently shown across the reading, spelling, and mathematics domains using test and teaching rating data. A comparison between the PASS and the SDQ-1 demonstrated concurrent validity across self-concept domains. Conclusion. The findings support the notions that the social environment is a significant agent that influences self-concept, and that teacher ratings and standardised tests of achievement and the PASS and the SDQ-1 are valid measures for self-concept research.

Performance on tests sensitive to impaired executive ability in schizophrenia, mania and well controls: acute and subacute phases

Aims: To compare the performance of schizophrenia, mania and well control groups on tests sensitive to impaired executive ability, and to assess the within-group stability of these measures across the acute and subacute phases of psychoses. Method: Recently admitted patients with schizophrenia (n=36), mania (n=18) and a well control group (n=20) were assessed on two occasions separated by 4 weeks. Tests included: the Controlled Oral Word Association Test, the Stroop Test, the Wisconsin Card Sort Test, and the Trail Making Test. Results: The two patient groups were significantly impaired on the Stroop Test at both time points compared to the control group. Significant group differences were also found for the Trail Making Test at Time 1 and for the Wisconsin Card Sort Test at Time 2. When controlled for practice effect, significant improvements over time were found on the Stroop and Trail Making tests in the schizophrenia group and on WCST Categories Achieved in the mania group. Discussion: Compared to controls, the patient groups were impaired on measures related to executive ability. The pattern of improvement on test scores between the acute and subacute phases differed between patients with schizophrenia versus patients with mania. (C) 1997 Elsevier Science B.V.