Improving the precision of the accumulated oxygen deficit using VO2-power regression points from below and above the lactate threshold

The accumulated oxygen deficit (AOD) method assumes a linear VO₂-power relationship for exercise intensities increasing from below the lactate threshold (BLT) to above the lactate threshold (ALT). Factors that were likely to effect the linearity of the VO₂-power regression and the precision of the estimated total energy demand (ETED) were investigated. These included the slow component of VO₂ kinetics (SC), a forced resting y-intercept and exercise intensities BLT and ALT. Criteria for linearity and precision included the Pearson correlation coefficient (PCC) of the VO₂-power relationship, the length of the 95% confidence interval (95% CI) of the ETED and the standard error of the predicted value (SEP), respectively. Eight trained male and one trained female triathlete completed the required cycling tests to establish the AOD when pedalling at 80 rev/min. The influence of the SC on the linear extrapolation of the ETED was reduced by measuring VO₂ after three min of exercise. Measuring VO₂ at this time provided a new linear extrapolation method consisting of ten regression points spread evenly from BLT and ALT. This method produced an ETED with increased precision compared to using regression equations developed from intensities BLT with no forced y-intercept value; (95%CI (L), 0.70±0.26 versus 1.85±1.10, P<0.01; SEP(L/Watt), 0.07±0.02 versus 0.28±0.17; P<0.01). Including a forced y-intercept value with five regression points either BLT or ALT increased the precision of estimating the total energy demand to the same level as when using 10 regression points, (5 points BLT + y-intercept versus 5 points ALT + y-intercept versus 10 points; 95%CI(l), 0.61±0.32, 0.87±0.40, 0.70±0.26; SEP(L/Watt), 0.07±0.03, 0.08±0.04, 0.07±0.02; p>0.05). The VO₂-power regression can be designed using a reduced number of regression points... ABSTRACT FROM AUTHOR

The need for a higher custody threshold for indigenous offenders in Victoria

Over-representation of indigenous persons in the criminal justice system has changed little since the Royal Commission into Aboriginal Deaths in Custody (RCIADIC) - claim by the Victorian Department of Justice that a key recommendation of RCIADIC had been implemented, namely that imprisonment should be a sentence of last resort for indigenous offenders - how to ensure that imprisonment is a sanction of last resort when indigenous prisoners present for sentence.

A complex relationship among chemical concentration, detection threshold and suprathreshold intensity of bitter compounds

Detection thresholds and psychophysical curves were established for caffeine, quinine-HCl (QHCl), and propylthiouracil (PROP) in a sample of 33 subjects (28 female mean age 24 ± 4). The mean detection threshold (±standard error) for caffeine, QHCl, and PROP was 1.2 ± 0.12, 0.0083 ± 0.001, and 0.088 ± 0.07 mM, respectively. Pearson product–moment analysis revealed no significant correlations between detection thresholds of the compounds. Psychophysical curves were constructed for each bitter compound over 6 concentrations. There were significant correlations between incremental points of the individual psychophysical curves for QHCl and PROP. Regarding caffeine, there was a specific concentration (6 mM) below and above which the incremental steps in bitterness were correlated. Between compounds, analysis of psychophysical curves revealed no correlations with PROP, but there were significant correlations between the bitterness of caffeine and QHCl at higher concentrations on the psychophysical curve (P < 0.05). Correlation analysis of detection threshold and suprathreshold intensity within a compound revealed a significant correlation between PROP threshold and suprathreshold intensity (r = 0.46–0.4, P < 0.05), a significant negative correlation for QHCl (r = –0.33 to –0.4, P < 0.05), and no correlation for caffeine. The results suggest a complex relationship between chemical concentration, detection threshold, and suprathreshold intensity.

The behaviour of US stock prices : evidence from a threshold autoregressive model

This paper investigates the behaviour of US stock prices using an unrestricted two-regime threshold autoregressive (TAR) model with an autoregressive unit root. The TAR model is applied to monthly stock price (NYSE Common Stocks) data for the US for the period 1964:06 to 2003:04. Amongst our main results, we find that the US stock price is a nonlinear series that is characterized by a unit root process, consistent with the efficient market hypothesis.

Are nominal exchange rates and price levels co-integrated? new evidence from threshold autoregressive and momentum-threshold autoregressive models

The goal of this paper is to examine evidence for co-integration between nominal exchange rates for Canada, the UK, Japan, Germany, Italy and France (G6) vis-à-vis the US dollar, and the relative price ratios using monthly data over the period 1973:01 to 1997:04. Motivated by the fact that exchange rate adjustment may be asymmetric, we allowed for asymmetric adjustment in exchange rates by using the threshold autoregressive model and the momentum threshold autoregressive model. We do not find any evidence of a co-integrating relationship; hence, we fail to establish long-run purchasing power parity.

Threshold effects of glucose transporter-4 (GLUT4) deficiency on cardiac glucose uptake and development of hypertrophy

The aim of this study was to investigate the metabolic and structural consequences of a decrease in glucose transporter-4 (GLUT4) levels on the heart. The CreLoxP system was utilised to delete GLUT4 in muscle tIssue including heart. The presence of the PGK-neoR cassette in the GLUT4-Lox mice resulted in reduced expression in all tIssues to levels 15-30% of wild-type control mice. In mice expressing Cre recombinase, there was a further reduction of GLUT4 in cardiac tIssue to almost undetectable levels. Cardiac glucose uptake was measured basally and during a uglycaemic/hyperinsulinaemic clamp using 2-deoxy-[1-(14)C]glucose. Insulin-stimulated glucose uptake was normal in hearts expressing 15% of normal GLUT4 levels but markedly reduced in mice with more profound reduction in GLUT4. Cardiac enlargement occurred only when GLUT4 levels were less than 5% of normal values. In heart there is a threshold level of GLUT4 above which insulin-stimulated glucose uptake is maintained. As little as 5% of normal GLUT4 levels expressed in heart is sufficient to prevent the development of cardiac hypertrophy. 2-deoxy-[1-14C]glucose. Insulin-stimulated glucose uptake was normal in hearts expressing 15% of normal GLUT4 levels but markedly reduced in mice with more profound reduction in GLUT4. Cardiac enlargement occurred only when GLUT4 levels were less than 5% of normal values. In heart there is a threshold level of GLUT4 above which insulin-stimulated glucose uptake is maintained. As little as 5% of normal GLUT4 levels expressed in heart is sufficient to prevent the development of cardiac hypertrophy.

An in vivo cytotoxicity threshold for influenza A virus-specific effector and memory CD8+ T cells

Influenza A virus infection of C57BL/6 (B6) mice is characterized by prominent CD8 T cell responses to H2Db complexed with peptides from the viral nucleoprotein (NP366, ASNENMETM) and acid polymerase (PA224, SSLENFRAYV). An in vivo cytotoxicity assay that depends on the adoptive transfer of peptide-pulsed, syngeneic targets was used in this study to quantitate the cytotoxic potential of DbNP366- and DbPA224-specific acute and memory CD8 T cells following primary or secondary virus challenge. Both T cell populations displayed equivalent levels of in vivo effector function when comparable numbers were transferred into naive B6 hosts. Cytotoxic activity following primary infection clearly correlated with the frequency of tetramer-stained CD8 T cells. This relationship looked, however, to be less direct following secondary exposure, partly because the numbers of CD8DbNP366 T cells were greatly in excess. However, calculating the in vivo E:T ratios indicated that in vivo lysis, like many other biological functions, is threshold dependent. Furthermore, the capacity to eliminate peptide-pulsed targets was independent of the differentiation state (i.e., primary or secondary effectors) and was comparable for the two T cell specificities that were analyzed. These experiments provide insights that may be of value for adoptive immunotherapy, where careful consideration of both the activation state and the number of effector cells is required.

The end of economic growth? A contracting threshold hypothesis

This paper argues that GDP growth in both developed and developing countries has associated costs that can outweigh the benefits and thus reduce sustainable well-being. This conclusion is based upon the findings of empirical applications of the Genuine Progress Indicator (GPI) to a range of countries in the Asia-Pacific region. The studies conducted on seven Asia-Pacific countries indicate that, in the case of five of the seven nations, more recent GDP growth has reduced the sustainable well-being experienced by the average citizen residing within them. Moreover, the threshold point at which the costs of GDP growth outweigh the benefits appears to be contracting (i.e., occurring at a much lower per capita level of GDP). This paper therefore introduces a new contracting threshold hypothesis: as the economies of the Asia-Pacific region and the world collectively expand in a globalised economic environment, there is a contraction over time in the threshold level of per capita GDP. As a consequence, the threshold point confronting growth late-comers (i.e., developing countries) occurs at a much lower level of sustainable welfare than what wealthy nations currently enjoy. The consequences of this for developing countries are clearly significant and require a new approach to economic development.

Dynamic threshold determination by local and global edge evaluation

In this paper we consider two methods for automatically determining values for thresholding edge maps. In contrast to most other related work they are based on the figural rather than statistical properties of the edges. The first approach applies a local edge evaluation measure based on edge continuity and edge thinness to determine the threshold on edge magnitude. The second approach is more global and considers complete connected edge curves. The curves are mapped onto an edge curve length/average magnitude feature space, and a robust technique is developed to partition this feature space into true and false edge regions. A quantitative assessment of the results on synthetic data shows that the global method performs better than the local method. Furthermore, a qualitative assessment of its application to a variety of real images shows that it reliably produces good results.

Threshold dynamic time warping for spatial activity recognition

Non-invasive spatial activity recognition is a difficult task, complicated by variation in how the same activities are conducted and furthermore by noise introduced by video tracking procedures. In this paper we propose an algorithm based on dynamic time warping (DTW) as a viable method with which to quantify segmented spatial activity sequences from a video tracking system. DTW is a widely used technique for optimally aligning or warping temporal sequences through minimisation of the distance between their components. The proposed algorithm threshold DTW (TDTW) is capable of accurate spatial sequence distance quantification and is shown using a three class spatial data set to be more robust and accurate than DTW and the discrete hidden markov model (HMM). We also evaluate the application of a band dynamic programming (DP) constraint to TDTW in order to reduce extraneous warping between sequences and to reduce the computation complexity of the approach. Results show that application of a band DP constraint to TDTW improves runtime performance significantly, whilst still maintaining a high precision and recall.

Dynamic threshold determination by local and global edge evaluation

In this paper we consider two methods for automatically determining values for thresholding edge maps. Rather than use statistical methods they are based on the figural properties of the edges. Two approaches are taken. We investigate applying an edge evaluation measure based on edge continuity and edge thinness to determine the threshold on edge strength. However, the technique is not valid when applied to edge detector outputs that are one-pixel wide. In this case, we use a measure based on work by Lowe for assessing edges. This measure is based on length and average strength of complete linked edge lists.