On conditional diagnosability of the folded hypercubes

The n-dimensional folded hypercube FQ_n, a variation of the hypercube proposed by Ahmed et al. [A. El-Amawy, S. Latifi, Properties and performance of folded hypercubes, IEEE Transactions on Parallel and Distributed Systems 2(3) (1991) 31-42], is an (n + 1)-regular (n + 1)-connected graph. Conditional diagnosability, a new measure of diagnosability introduced by Lai et al. [Pao-Lien Lai, Jimmy J.M. Tan, Chien-Ping Chuang, Lih-Hsing Hsu, Conditional diagnosability measures for large multiprocessor systems, IEEE Transactions on Computers 54(2) (2005) 165-175] can better measure the diagnosability of regular interconnection networks. This paper determines that under PMC-model the conditional diagnosability of FQ_n (t_c(FQ_n)) is 4n − 3 when n = 5 or n ? 8; t_c(FQ₃) = 3, t_c(FQ₄) = 7.     

Testing the potential of multi-spectral remote sensing for retrospectively estimating fire severity in African Savannahs

The remote sensing of fire severity is a noted goal in studies of forest and grassland wildfires. Experiments were conducted to discover and evaluate potential relationships between the characteristics of African savannah fires and post-fire surface spectral reflectance in the visible to shortwave infrared spectral region. Nine instrumented experimental fires were conducted in semi-arid woodland savannah of Chobe National Park (Botswana), where fire temperature (T_max) and duration (dt) were recorded using thermocouples positioned at different heights and locations. These variables, along with measures of fireline intensity (FLI), integrated temperature with time (T_sum) and biomass (and carbon/nitrogen) volatilised were compared to post-fire surface spectral reflectance. Statistically significant relationships were observed between (i) the fireline intensity and total nitrogen volatilised (r² = 0.54, n = 36, p < 0.001), (ii) integrated temperature (T_sum−μ) and total biomass combusted (r² = 0.72, n = 32, p < 0.001), and (iii) fire duration as measured at the top-of-grass sward thermocouple (dt_T) and total biomass combusted (r² = 0.74, n = 34, p < 0.001) and total nitrogen volatilised (r² = 0.73, n = 34, p < 0.001). The post-fire surface spectral reflectance was found to be related to dt and T_sum via a quadratic relationship that varied with wavelength. The use of visible and shortwave infrared band ratios produced statistically significant linear relationships with fire duration as measured by the top thermocouple (dt_T) (r² = 0.76, n = 34, p < 0.001) and the mean of T_sum (r² = 0.82, n = 34, p < 0.001). The results identify fire duration as a versatile measure that relates directly to the fire severity, and also illustrate the potential of spectrally-based fire severity measures. However, the results also point to difficulties when applying such spectrally-based techniques to Earth Observation satellite imagery, due to the small-scale variability noted on the ground. Results also indicate the potential for surface spectral reflectance to increase following higher severity fires, due to the laying down of high albedo white mineral ash. Most current techniques for mapping burned area rely on the general assumption that surface albedo decreases following a fire, and so if the image spatial resolution was high enough such methods may fail. Determination of the effect of spatial resolution on a sensor's ability to detect white ash was investigated using a validated optical mixture modelling approach. The most appropriate mixing model to use (linear or non-linear) was assessed using laboratory experiments. A linear mixing model was shown most appropriate, with results suggesting that sensors having spatial resolutions significantly higher than those of Landsat ETM+ will be required if patches of white ash are to be used to provide EO-derived information on the spatial variation of fire severity.     

Remote sensing of water clarity in Tampa Bay

We examined the spatial and temporal variability of the Secchi Disk Depth (SDD) within Tampa Bay, Florida, using the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) satellite imagery collected from September 1997 to December 2005. SDD was computed using a two-step process, first estimating the diffuse light attenuation coefficient at 490 nm, K_d(490), using a semi-analytical algorithm and then SDD using an empirical relationship with K_d(490). The empirical SDD algorithm (SDD = 1.04 × K_d(490)^− 0.82, 0.9 < SDD < 8.0 m, r² = 0.67, n = 80) is based on historical SDD observations collected by the Environmental Protection Commission of Hillsborough County (EPCHC) in Tampa Bay. SeaWiFS derived SDD showed distinctive seasonal variability, attributed primarily to chlorophyll concentrations and color in the rainy season and to turbidity in the dry season, which are in turn controlled by river runoff and winds or wind-induced sediment resuspension, respectively. The Bay also experienced strong interannual variability, mainly related to river runoff variability. As compared to in situ single measurements, the SeaWiFS data provide improved estimates of the “mean” water clarity conditions in this estuary because of the robust, frequent, and synoptic coverage. Therefore we recommend incorporation of this technique for routine monitoring of water quality in coastal and large estuarine waters like Tampa Bay.     

Monitoring turbidity in Tampa Bay using MODIS/Aqua 250-m imagery

We developed an approach to map turbidity in estuaries using a time series (May 2003 to April 2006) of 250-m resolution images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite, using Tampa Bay as a case study. Cross-calibration of the MODIS 250-m data (originally designed for land use) with the well-calibrated MODIS 1-km ocean data showed that the pre-launch radiometric calibration of the 250-m bands was adequate. A simple single scattering atmospheric correction provided reliable retrievals of remote sensing reflectance at 645 nm (0.002 < R_rs(645) < 0.015 sr^− 1, median bias = − 7%, slope = 0.95, intercept = 0.00, r² = 0.97, n = 15). A more rigorous approach, using a multiple scattering atmospheric correction of the cross-calibrated at-sensor radiances, retrieved similar R_rs(645). R_rs(645) estimates, after stringent data quality control, showed a close correlation with in situ turbidity (turbidity = 1203.9 × R_rs(645)^1.087, 0.9 < turbidity < 8.0 NTU, r² = 0.73, n = 43). MODIS turbidity imagery derived using the developed approach showed that turbidity in Hillsborough Bay (HB) was consistently higher than that in other sub-regions except in August and September, when higher concentrations of colored dissolved organic matter seem to have caused underestimates of turbidity. In comparison, turbidity in Middle Tampa Bay (MTB) was generally lowest among the Bay throughout the year. Both Old Tampa Bay (OTB) and Low Tampa Bay (LTB) showed marked seasonal variations with higher turbidity in LTB during the dry season and in OTB during the wet season, respectively. This seasonality is linked to wind-driven bottom resuspension events in lower portion of the Bay and river inputs of sediments in the upper portion of the Bay. The Bay also experiences significant interannual variation in turbidity, which was attributed primarily to changes in wind forcing. Compared with the once-per-month, non-synoptic in situ surveys, synoptic and frequent sampling facilitated by satellite remote sensing provides improved assessments of turbidity patterns and thus a valuable tool for operational monitoring of water quality of estuarine and coastal waters such as in Tampa Bay.     

Asymptotic behavior and blow up of solutions for semilinear parabolic equations at critical energy level

In this paper we study the initial boundary value problem of semilinear parabolic equations with semilinear term f(u). By using the family of potential wells method we prove that if f(u) satisfies some conditions, J(u₀) ≤ d and I(u₀) > 0, then the solution decays to zero exponentially as t → ∞. On the other hand, if J(u₀) ≤ d, I(u₀) < 0, then the solution blows up in finite time.     

Evaluation of three methodologies to estimate the VO2max in people of different ages

Aging and gender are factors that affect the variation of physical work capacity. The present paper highlights the importance of the metabolism used by ergonomics to establish the appropriate limits of loads at work. This study compares the aerobic capacity of people from 20 to 71 years old split in 5 different groups. The laboratory experiment tested 33 volunteers (19 women and 14 men). A submaximal step test was used to measure the VO₂ using a portable breath by breath metabolic system and a telemetric heart rate monitor. Three methods to estimate the VO_2max were compared: 1) a direct measurement of VO₂, 2) estimation by heart rate, and 3) a step test method using predetermined charts. Significant difference was encountered among the estimation methods as well as among the age ranges (F_2,92 = 6.43, p < 0.05 y F_4,92 = 7.18, p < 0.05 respectively). The method of direct measurement and the method of predetermined charts were different for the estimation of the VO_2max with a confidence level of 95%. The method of predetermined charts is better adapted for males and people younger than 30 years. The estimation through non invasive heart rate apparatus was a good appraiser of the maximal oxygen consumption considering both genders and all the age groups.     

Comparison of MODIS, eddy covariance determined and physiologically modelled gross primary production (GPP) in a Douglas-fir forest stand

Quantification of the magnitude of net terrestrial carbon (C) uptake, and how it varies inter-annually, is an important question with future potential sequestration influenced by both increased atmospheric CO₂ and changing climate. However the assessment of differences in measured and modeled C accumulation is a challenging task due to the significant fine scale variation occurring in terrestrial productivity due to soil, climate and vegetation characteristics as well as difficulties in measuring carbon accumulation over large spatial areas. The Moderate Resolution Imaging Spectroradiometer (MODIS) offers a means of monitoring gross primary production (GPP), both spatially and temporally, routinely from space. However it is critical to compare and contrast the temporal dynamics of the C and water fluxes with those measured from ground-based networks, or estimated using physiological models. In this paper, using a number of approaches, our objective is to determine if any systematic biases exists in either the MODIS, or the modeled estimates of fluxes, relative to the measurements made over an evergreen, needleleaf temperate rainforest on Vancouver Island, Canada. Results indicate that 8-day GPP as predicted with a simple physiological model (3PGS), forced using local meteorology and canopy characteristics, matched measured fluxes very well (r² = 0.86, p < 0.001) with no significant difference between eddy covariance (EC) and modeled GPP (p < 0.001). In addition, modeled water supply closely matched measured relative available soil water content at the site. Using canopy characteristics from the MODIS fraction of photosynthetically active radiation (fPAR) algorithm, slightly reduced the correspondence of the predictions due to a large number of unsuccessful retrievals (83%) due to sun angle, snow and cloud. Predictions of GPP based on the MODIS GPP algorithm, forced using local meteorology and canopy characteristics, were also highly correlated with EC measurements (r² = 0.89, p < 0.001) however these estimates were biased under predicting GPP. Estimates of GPP based on the most recent MODIS reprocessing (collection 4.5) remained highly correlated (r² = 0.88, p < 0.001) yet were also the most biased with the estimates being 30% less than the EC-measured GPP. Most of the variance in GPP at the site was explained by the absorbed photosynthetically active radiation. We also compared the nighttime respiration as measured over 2 years at the site with the minimum 8-day MODIS land surface temperature and found a significant relationship (r² = 0.57), similar to other studies.     

Diagnosable evaluation of DCC linear congruential graphs under the PMC diagnostic model

A DCC (disjoint consecutive cycles) linear congruential graph G(F, n) consists of n nodes and is generated by a set of linear functions F with special properties. It was proved that G(F, n) is a 2t-regular graph and has connectivity 2t, where t=|F| and 1?t?p-1 (n=2^p for some integer p). For a multiprocessor system, its diagnosability is critical to measure the performance. In this paper, we study the diagnosability of G(F,2^p) under the precise and pessimistic diagnosis strategies based on the PMC (Preparata, Metze, and Chien) diagnostic model. It is proved that G(F,2^p) is 2t-diagnosable and (4t-5)/(4t-5)-diagnosable under the two diagnosis strategies, respectively, where p?3 and 2?t?p-1. In addition, the diagnosability of DCC linear congruential graphs is compared with that of BC (bijective connection) graphs.     

Small deviations for two classes of Gaussian stationary processes and <Emphasis Type="Italic">L</Emphasis><Superscript><Emphasis Type="Italic">p</Emphasis></Superscript>-functionals, 0 < <Emphasis Type="Italic">p</Emphasis> ≤ ∞

Let w(t) be a standard Wiener process, w(0) = 0, and let η _a (t) = w(t + a) − w(t), t ≥ 0, be increments of the Wiener process, a > 0. Let Z _a (t), t ∈ [0, 2a], be a zeromean Gaussian stationary a.s. continuous process with a covariance function of the form E Z _a (t)Z _a (s) = 1/2[a − |t − s|], t, s ∈ [0, 2a]. For 0 < p < ∞, we prove results on sharp asymptotics as ɛ → 0 of the probabilities

The effects of video on cognitive load and social presence in multimedia-learning

Two studies examined the use of video in multimedia learning environments. In Study 1, participants (N = 26) viewed one of two versions of a computer-based multimedia presentation: video, which included a video of a lecture with synchronized slides, or no video, which included the slides but only an audio narration of the lecture. Learning, cognitive load and social presence were assessed, but a significant difference was found only for cognitive load, with video experiencing greater cognitive load, t (24) = 2.45, p < .05. In Study 2, students (N = 25) were randomly assigned to either video or no video condition. Background knowledge and visual/verbal learning preference were assessed before viewing the presentation, and learning, cognitive load, and social presence were assessed after viewing. No significant differences were found for learning or social presence. However, a significant visual/verbal learning preference by condition interaction was found for cognitive load, F (1,21) = 4.51, p < .05: low visual-preference students experienced greater cognitive load in the video condition, while high visual-preference students experienced greater cognitive load in the no video condition.     

Impact of test-driven development on productivity, code and tests: A controlled experiment

Context

Test-driven development is an approach to software development, where automated tests are written before production code in highly iterative cycles. Test-driven development attracts attention as well as followers in professional environment; however empirical evidence of its superiority regarding its effect on productivity, code and tests compared to test-last development is still fairly limited. Moreover, it is not clear if the supposed benefits come from writing tests before code or maybe from high iterativity/short development cycles.

Objective

This paper describes a family of controlled experiments comparing test-driven development to micro iterative test-last development with emphasis on productivity, code properties (external quality and complexity) and tests (code coverage and fault-finding capabilities).

Method

Subjects were randomly assigned to test-driven and test-last groups. Controlled experiments were conducted for two years, in an academic environment and in different developer contexts (pair programming and individual programming contexts). Number of successfully implemented stories, percentage of successful acceptance tests, McCabe’s code complexity, code coverage and mutation score indicator were measured.

Results

Experimental results and their selective meta-analysis show no statistically significant differences between test-driven development and iterative test-last development regarding productivity (χ²(6) = 4.799, p = 1.0, r = .107, 95% CI (confidence interval): −.149 to .349), code complexity (χ²(6) = 8.094, p = .46, r = .048, 95% CI: −.254 to .341), branch coverage (χ²(6) = 13.996, p = .059, r = .182, 95% CI: −.081 to .421), percentage of acceptance tests passed (one experiment, Mann-Whitney U = 125.0, p = .98, r = .066) and mutation score indicator (χ²(4) = 3.807, p = .87, r = .128, 95% CI: −.162 to .398).

Conclusion

According to our findings, the benefits of test-driven development compared to iterative test-last development are small and thus in practice relatively unimportant, although effects are positive. There is an indication of test-driven development endorsing better branch coverage, but effect size is considered small.     

A portable device for the assessment of dynamic visual acuity

Dynamic visual acuity (DVA) thresholds are among the few visual functions predictive of automobile crashes. DVA is also sensitive to alcohol and aging. However, measuring DVA is awkward because there is no standardized, efficient, flexible apparatus for DVA assessment. In this project, we developed a prototype of an automated, portable DVA system using a low-energy laser, and we compared this laser DVA with the traditional device in two within-subjects, repeated measures designs. The two studies included 48 participants (22 males and 26 females with an average age of 18.33 years). The most important findings were that: (1) retest reliabilities of the two DVA devices were comparable and higher with the laser; (2) average correlations between the two devices were r = 0.62 (p < 0.01) and r = 0.65 (p < 0.01) for the two designs respectively; and (3) after correction for reliability attenuation these improved to r = 0.92 and r = 0.78. These findings indicate that a flexible DVA laser device can be developed to measure the same construct as the more traditional bulky DVA device.     

Remote sensing of photosynthetic light-use efficiency across two forested biomes: Spatial scaling

Eddy covariance (EC) measurements have greatly advanced our knowledge of carbon exchange in terrestrial ecosystems. However, appropriate techniques are required to upscale these spatially discrete findings globally. Satellite remote sensing provides unique opportunities in this respect, but remote sensing of the photosynthetic light-use efficiency (ε), one of the key components of Gross Primary Production, is challenging. Some progress has been made in recent years using the photochemical reflectance index, a narrow waveband index centered at 531 and 570 nm. The high sensitivity of this index to various extraneous effects such as canopy structure, and the view observer geometry has so far prevented its use at landscape and global scales. One critical aspect of upscaling PRI is the development of generic algorithms to account for structural differences in vegetation. Building on previous work, this study compares the differences in the PRI: ? relationship between a coastal Douglas-fir forest located on Vancouver Island, British Columbia, and a mature Aspen stand located in central Saskatchewan, Canada. Using continuous, tower-based observations acquired from an automated multi-angular spectro-radiometer (AMSPEC II) installed at each site, we demonstrate that PRI can be used to measure ? throughout the vegetation season at the DF-49 stand (r² = 0.91, p < 0.00) as well as the deciduous site (r² = 0.88, p < 0.00). It is further shown that this PRI signal can be also observed from space at both sites using daily observations from the Moderate Resolution Imaging Spectro-radiometer (MODIS) and a multi-angular implementation of atmospheric correction (MAIAC) (r² = 0.54 DF-49; r² = 0.63 SOA; p < 0.00). By implementing a simple hillshade model derived from airborne light detection and ranging (LiDAR) to approximate canopy shadow fractions (α_s), it is further demonstrated that the differences observed in the relationship between PRI and ε at DF-49 and SOA can be attributed largely to differences in α_s. The findings of this study suggest that algorithms used to separate physiological from extraneous effects in PRI reflectance may be more broadly applicable and portable across these two climatically and structurally different biome types, when the differences in canopy structure are known.     

Self-regulated learning through writing on computers: Consequences for reading comprehension

The overall aim for the present study was to analyze the consequences for reading ability among the children of a computer supported self-regulated learning environment in grade two. By means of a quasi-experimental design in a natural setting, an experimental group (n = 39) was compared to a control group from a national sample (n = 3409) on reading comprehension. The statistical analyses showed that the experimental group achieved better on reading comprehension both as a group (p < .001) as well as girls (p < .001) and boys (p < .05) separately. The proportion of high achievers was higher, and the proportion of low achievers was lower in the experimental group. In order to explain the level of reading comprehension in the experimental group Structural Equation Modelling (SEM) was used. The main explanatory factor for reading comprehension was writing with β = .44. As a tentative conclusion it was suggested that the extended writing in combination with the self-regulated learning environment can promote reading comprehension in grade two, whereas home literacy had no impact on reading comprehension in this context.     

Evaluation of lifestyle risk factors and job status associated with back injuries among employees at a mid-western university

For decades the literature has shown an association between work-related risk factors and back injuries among employees. However, only recently, there is a growing body of literature that suggests lifestyle risk factors may also be associated with back injuries. The purpose of this research was to determine if selected lifestyle risk factors are associated with a greater risk of back injuries. Further, there may be an association between job status and incident reporting, lost workdays cases and workers' compensation (WC) paid for back injuries among university employees. Aggregate data from a Health Risk Assessment (HRA) questionnaire were used to analyze 6053 university employees for lifestyle risk factors associated with back injuries. Of the total sample, 57% (n = 3471) were female; 46% (n = 2778) worked as clerical or service staff; and the mean age was 45 years. Pearson chi-square (χ²) analyses indicate that job status (χ² = 307.07, df = 4, p < .001) and gender (χ² = 40.14, df = 2, p < .001) were associated with high risk back score. An ordinal regression analysis predicted that participants who exercised vigorously for at least 20 min, 3 or more days per week, or 3 or more days per week of combined vigorous exercise and moderate-intensity physical activity are almost 30 times less likely to have a high back risk score compared to participants who do not exercise vigorously or participate in less than 3 days per week of moderate-intensity physical activity (OR = 29.68, 95% CI = 25-35.25, p < .001). Participants who have a low risk score for BMI are three times less likely (OR = 3.20, 95% CI = 2.74-3.75, p < .001) to have a high back risk score when compared to participants who have a high risk score for BMI. A regression tree predicted high back risk scores were participants who: (1) receive an adequate amount of physical activity or vigorous exercise and is a male service or clerical staff; (2) do not receive an adequate amount of physical activity or vigorous exercise, and is not overweight; or (3) who do not receive an adequate amount of physical activity or vigorous exercise, and is overweight. Six years of Occupational Safety and Health Administration (OSHA) 300 logs and WC claims data paid for back injuries supported the finding that clerical or service staff had the greatest risk of back injuries. Based on the results of this study, there appears to be an association between lifestyle risk factors, job status and back injuries among university employees. We believe our evaluation approach may be used to study other work populations to verify the outcomes observed in this study.     

Improved crystalline structure and H2S sensing performance of CuO-Au-SnO2 thin film using SiO2 additive concentration

In situ SiO₂-doped SnO₂ thin films were successfully prepared by liquid phase deposition. The influence of SiO₂ additive as an inhibitor on the surface morphology and the grain size for the thin film has been investigated. These results show that the morphology of SnO₂ film changes significantly by increasing the concentration of H₂SiF₆ solution which decreases the grain size of SnO₂. The stoichiometric analysis of Si content in the SnO₂ film prepared from various Si/Sn molar ratios has also been estimated. For the sensing performance of H₂S gas, the SiO₂-doped Cu-Au-SnO₂ sensor presents better sensitivity to H₂S gas compared with Cu-Au-SnO₂ sensor due to the fact that the distribution of SiO₂ particles in grain boundaries of nano-crystallines SnO₂ inhibited the grain growth (<6 nm) and formed a porous film. By increasing the Si/Sn molar ratio, the SiO₂-doped Cu-Au-SnO₂ gas sensors (Si/Sn = 0.5) exhibit a good sensitivity (S = 67), a short response time (t_90% < 3 s) and a good gas concentration characteristic (α = 0.6074). Consequently, the improvement of the nano-crystalline structures and high sensitivity for sensing films can be achieved by introducing SiO₂ additive into the SnO₂ film prepared by LPD method.     

Load-sharing system model and its application to the real data set

This study deals with the classical and Bayesian estimation of the parameters of a k-components load-sharing parallel system model in which each component's lifetime follows Lindley distribution. Initially, the failure rate of each of the k components in the system is h(t,θ₁) until the first component failure. However, upon the first failure within the system, the failure rates of the remaining (k − 1) surviving components change to h(t,θ₂) and remain the same until next failure. After second failure, the failure rates of (k − 2) surviving components change to h(t,θ₃) and finally when the (k − 1)th component fails, the failure rate of the last surviving component becomes h(t,θ_k). In classical set up, the maximum likelihood estimates of the load share parameters, system reliability and hazard rate functions along with their standard errors are computed. 100 × (1 − γ)% confidence intervals and two bootstrap confidence intervals for the parameters have also been constructed. Further, by assuming Jeffrey's invariant and gamma priors of the unknown parameters, Bayes estimates along with their posterior standard errors and highest posterior density credible intervals of the parameters are obtained. Markov Chain Monte Carlo technique such as Metropolis–Hastings algorithm has been utilized to generate draws from the posterior densities of the parameters.     

Exact solution of mixed problems for variable coefficient one-dimensional diffusion equation

This paper deals with diffusion problems modeled by the equation a(t)u_xx = u_t, x > 0, t > 0, u(x, 0) = c(x) together with the boundary condition u(0, t) = b(t) or u_x(0, t) = b(t). By using Fourier transforms, existence conditions and exact solutions of the above mixed problems are given.     

Über einen Ordnungsbegriff bei Einbettungsalgorithmen zur Lösung nichtlinearer Gleichungen

For solving the nonlinear systemF(x)=0 by using a continuation method a functionz implicitly defined byH(z, t)=0 has to be determined. In order to obtain approximationsz ^k toz(t _k ) the algorithmz ^k+1:=z ^k ?τ _k p(z ^k ,t _k , τ _k ),t _k+1:=t _k +τ _k , is used. The order of such a functionp is defined in this paper, and for certain classes of algorithms the corresponding orders are determined.     

Cyclic codes over R = Fp + uFp +?+ uFp with length pn

In this paper, all cyclic codes with length p^sn, (n prime to p) over the ring R = F_p + uF_p +?+ u^k−1F_p are classified. It is first proved that Tor_j(C) is an ideal of , so that the structure of ideals over extension ring S_u^k(m,ω)=GR(u^k,m)[ω]/〈ω^ps-1〉 is determined. Then, an isomorphism between R[X]/〈X^N − 1〉 and a direct sum ⊕_h∈IS_u^k(m_h,ω) can be obtained using discrete Fourier transform. The generator polynomial representation of the corresponding ideals over F_p + uF_p +?+ u^k−1F_p is calculated via the inverse isomorphism. Moreover, torsion codes, MS polynomial and inversion formula are described.