The effect of speech and speech intelligibility on task performance

The aim of this study was to find out what are the effects of three different sound environments on performance of cognitive tasks of varying complexity. These three sound environments were ‘speech’, ‘masked speech’ and ‘continuous noise’. They corresponded to poor, acceptable and perfect acoustical privacy in an open-plan office, respectively. The speech transmission indices were 0.00, 0.30 and 0.80, respectively. Sounds environments were presented at 48 dBA. The laboratory experiment on 36 subjects lasted for 4 h for each subject. Proofreading performance deteriorated in the ‘speech’ (p < 0.05) compared to the other two sound environments. Reading comprehension and computer-based tasks (simple and complex reaction time, subtraction, proposition, Stroop and vigilance) remained unaffected. Subjects assessed the ‘speech’ as the most disturbing, most disadvantageous and least pleasant environment (p < 0.01). ‘Continuous noise’ annoyed the least. Subjective arousal was highest in ‘masked speech’ and lowest in ‘continuous noise’ (p < 0.05). Performance in real open-plan offices could be improved by reducing speech intelligibility, e.g. by attenuating speech level and using an appropriate masking environment.     

Subjective evaluation of running footwear depends on country and assessment method: a bi-national study

This study examined (1) the perception of running shoes between China (Beijing) and Singapore and (2) whether running shoe preference depended on assessment methods. One hundred (n = 50 each country) Chinese males subjectively evaluated four shoe models during running by using two assessment procedures. Procedure 1 used a visual analogue scale (VAS) to assess five perception variables. Procedure 2 was a ‘head-to-head’ comparison of two shoes simultaneously (e.g. left foot: A and right foot: B) to decide which model was preferred. VAS scores were consistently higher in Beijing participants (p < .001), indicating a higher degree of liking. Singapore participants used the lower end but a wider range of the 15 cm scale for shoe discrimination. Moderate agreement was seen between the VAS and ‘head-to-head’ procedures, with only 14 out of 100 participants matched all 6 pairwise comparisons (median = 4 matches). Footwear companies and researchers should be aware that subjective shoe preference may vary with assessment methods.

Practitioner Summary: Footwear preference depends on country and assessment methods. Running shoe perception differed between Beijing and Singapore Chinese, suggesting that footwear recommendation should be country-specific. Individuals' shoe preference measured by visual analogue scale when wearing complete pairs may not reflect that when directly comparing different models in left and right feet.     

Low power highly sensitive platform for gas sensing application

This paper reports a low power miniaturized MEMS based integrated gas sensor with 36.84 % sensitivity (ΔR/R₀) for as low as 4 ppm (NH₃) gas concentration. Micro-heater based gas sensor device presented here consumes very low power (360 °C at 98 mW/mm²) with platinum (Pt) micro-heater. Low powered micro-heater is an essential component of the metal oxide based gas sensors which are portable and battery operated. These micro-heaters usually cover less than 5 % of the gas sensor chip area but they need to be thermally isolated from substrate, to reduce thermal losses. This paper elaborates on design aspects of micro fabricated low power gas sensor which includes ‘membrane design’ below the microheater; the ‘cavity-to-active area ratio’; effect of silicon thickness below the silicon dioxide membrane; etc. using FEM simulations and experimentation. The key issues pertaining to process modules like fragile wafer handling after bulk micro-machining; lift-off of platinum and sensing films for the realization of heater, inter-digitated-electrodes (IDE) and sensing film are dealt with in detail. Low power platinum microheater achieving 700 °C at 267 mW/mm² are fabricated. Temperature calculations are based on experimentally calculated thermal coefficient of resistance (TCR) and IR imaging. Temperature uniformity and localized heating is verified with infrared imaging. Reliability tests of the heater device show their ruggedness and repeatability. Stable heater temperature with standard deviation (σ) of 0.015 obtained during continuous powering for an hour. Cyclic ON–OFF test on the device indicate the ruggedness of the micro-heater. High sensitivity of the device for was observed for ammonia (NH₃), resulting in 40 % response for ~4 ppm gas concentration at 230 °C operating temperature.     

Forest inventory stand height estimates from very high spatial resolution satellite imagery calibrated with lidar plots

Many areas of forest across northern Canada are challenging to monitor on a regular basis as a result of their large extent and remoteness. Although no forest inventory data typically exist for these northern areas, detailed and timely forest information for these areas is required to support national and international reporting obligations. We developed and tested a sample-based approach that could be used to estimate forest stand height in these remote forests using panchromatic Very High Spatial Resolution (VHSR, < 1 m) optical imagery and light detection and ranging (lidar) data. Using a study area in central British Columbia, Canada, to test our approach, we compared four different methods for estimating stand height using stand-level and crown-level metrics generated from the VHSR imagery. ‘Lidar plots’ (voxel-based samples of lidar data) are used for calibration and validation of the VHSR-based stand height estimates, similar to the way that field plots are used to calibrate photogrammetric estimates of stand height in a conventional forest inventory or to make empirical attribute estimates from multispectral digital remotely sensed data. A k-nearest neighbours (k-NN) method provided the best estimate of mean stand height (R ² = 0.69; RMSE = 2.3 m, RMSE normalized by the mean value of the estimates (RMSE-%) = 21) compared with linear regression, random forests, and regression tree methods. The approach presented herein demonstrates the potential of VHSR panchromatic imagery and lidar to provide robust and representative estimates of stand height in remote forest areas where conventional forest inventory approaches are either too costly or are not logistically feasible. While further evaluation of the methods is required to generalize these results over Canada to provide robust and representative estimation, VHSR and lidar data provide an opportunity for monitoring in areas for which there is no detailed forest inventory information available.     

Lumbar posture and trunk muscle activation during a typing task when sitting on a novel dynamic ergonomic chair

Low back pain (LBP) is a common musculoskeletal disorder and prolonged sitting often aggravates LBP. A novel dynamic ergonomic chair (‘Back App’), which facilitates less hip flexion while sitting on an unstable base has been developed. This study compared lumbar posture and trunk muscle activation on this novel chair with a standard backless office chair. Twelve painfree participants completed a typing task on both chairs. Lumbar posture and trunk muscle activation were collected simultaneously and were analysed using paired t-tests. Sitting on the novel dynamic chair significantly (p < 0.05) reduced both lumbar flexion and the activation of one back muscle (Iliocostalis Lumborum pars Thoracis). The discomfort experienced was mild and was similar (p > 0.05) between chairs. Maintaining lordosis with less muscle activation during prolonged sitting could reduce the fatigue associated with upright sitting postures. Studies with longer sitting durations, and in people with LBP, are required.

Practitioner Summary: Sitting on a novel dynamic chair resulted in less lumbar flexion and less back muscle activation than sitting on a standard backless office chair during a typing task among pain-free participants. Facilitating lordotic sitting with less muscle activation may reduce the fatigue and discomfort often associated with lordotic sitting postures.     

Spatio-temporal distribution of skipjack in relation to oceanographic conditions in the west-central Pacific Ocean

The skipjack tuna, Katsuwonus pelamis, is an economically important oceanic species widely distributed in the west-central Pacific Ocean (WCPO). The spatio-temporal distribution of Katsuwonus pelamis with respect to oceanographic and climatic variables during 1995–2010 in the west-central Pacific was examined in this study using purse seine fishery data from South Pacific Fisheries Commission (SPC). ‘Gravitational centre’ of two temporal scales (i.e. monthly and yearly) of catch per unit effort (CPUE) was calculated to represent the variability of local stock abundance on fishing grounds. Significant inter-annual and seasonal variabilities were observed. Monthly longitudinal ‘centres of gravity’ were correlated with sea surface temperature anomaly (SSTA) in Niño 3.4 region and monthly latitudinal ‘centres of gravity’ reflect a ‘South–North’ migration pattern of Katsuwonus pelamis. The distribution–habitat associations were quantitatively evaluated including SST between 28–30°C, sea surface height (SSH)in the range 90–100 cm, gradient SST between 0.1 and 0.7°C 10 km^?1,and chlorophyll-a(chl-a) between 0.1 and 0.6 mg m^?3 by an empirical cumulative distribution function (ECDF). Four clusters of yearly ‘gravitational centres’ were classified using the k-means method, which could be defined as warmpool fishing ground (WFG) and cold-tongue fishing ground (CFG) according to their oceanographic habitat. The integrated environmental distribution map combined with the developed model (R² = 0.28, p < 0.0001) provides an approach for predicting hotspots of Katsuwonus pelamis. This study improves our understanding of the spatio-temporal dynamics of skipjack tuna, which is critical for sustainable management of this important fisheries resources.     

Using MODIS time series data to estimate aboveground biomass and its spatio-temporal variation in Inner Mongolia’s grassland between 2001 and 2011

It is critical to understanding grassland biomass and its dynamics to study regional carbon cycles and the sustainable use of grassland resources. In this study, we estimated aboveground biomass (AGB) and its spatio-temporal pattern for Inner Mongolia’s grassland between 2001 and 2011 using field samples, Moderate Resolution Imaging Spectroradiometer normalized difference vegetation index (MODIS-NDVI) time series data, and statistical models based on the relationship between NDVI and AGB. We also explored possible relationships between the spatio-temporal pattern of AGB and climatic factors. The following results were obtained: (1) AGB averaged 19.1 Tg C (1 Tg = 10¹² g) over a total area of 66.01 × 10⁴ km² between 2001 and 2011 and experienced a general fluctuation (coefficient of variation = 9.43%), with no significant trend over time (R² = 0.05, p > 0.05). (2) The mean AGB density was 28.9 g C m^?2 over the whole study area during the 11 year period, and it decreased from the northeastern part of the grassland to the southwestern part, exhibiting large spatial heterogeneity. (3) The AGB variation over the 11 year period was closely coupled with the pattern of precipitation from January to July, but we did not find a significant relationship between AGB and the corresponding temperature changes. Precipitation was also an important factor in the spatial pattern of AGB over the study area (R² = 0.41, p < 0.001), while temperature seemed to be a minor factor (R² = 0.14, p < 0.001). A moisture index that combined the effects of precipitation and temperature explained more variation in AGB than did precipitation alone (R² = 0.45, p < 0.001). Our findings suggest that establishing separate statistical models for different vegetation conditions may reduce the uncertainty of AGB estimation on a large spatial scale. This study provides support for grassland administration for livestock production and the assessment of carbon storage in Inner Mongolia.     

Thermal imaging of Nisyros volcano (Aegean Sea) using ASTER data: estimation of radiative heat flux

A time series of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images (AST08) have been processed to allow radiative heat flux estimations of the Nisyros volcano. ASTER night-time images were acquired on four different dates: 7 April 2001, 13 June 2002, 26 October 2002 and 23 July 2005. The results show a steady state energy release with heat fluxes ranging from 15 to 30 W m^?2 over the craters of Kaminakia, Polyvotis and Stefanos, respectively. It is suggested that this range of values indicates a background heat flux of this volcano following the unrest of 1995–1997, and that the volcano has entered again into the quiet phase. Also, on the basis of the average spatial extent of the thermal anomaly a total radiative heat flux of 36 MW was estimated at the moment of ASTER overpass. Heat flux values for Nisyros are in good agreement with other published estimates derived from low-temperature fumarolic volcanoes (Stromboli and Vulcano, Italy) using Landsat TM data. It is also evidenced that the ASTER radiometer can be used as an important imaging tool for the monitoring of geophysical properties associated to volcanic activity, as is the volcanic heat flux.     

Automated,high temporal resolution,thermal analysis of Kilauea volcano,Hawai'i,using GOES satellite data

Thermal data are directly available from the Geostationary Operational Environmental Satellites (GOES) every 15 minutes at existing or inexpensively installed receiving stations. This data stream is ideal for monitoring high temperature features such as active lava flows and fires. To provide a near-real-time hot spot monitoring tool, we have developed, tested and installed software to analyse GOES data on-reception and then make results available in a timely fashion via the web. Our software automatically: (1) produces hot spot images and movies; (2) uses a thresholding procedure to generate a hot spot map; (3) updates hot spot radiance and cloud index time series; and (4) issues a threshold-based e-mail alert. Results are added to http://volcano1.pgd.hawaii.edu/goes/ within ～12 minutes of image acquisition and are updated every 15 minutes. Analysis of GOES data acquired for effusive activity at Kilauea volcano (Hawai'i) during 1997-98 show that short (<1 hour long) events producing 100m long (10² to 10³ m²) lava flows are detectable. This means that time constraints can be placed on sudden, rapidly evolving efflusive events with an accuracy of 7.5 minutes. Changes in activity style and extent can also be documented using hot spot size, intensity and shape. From radiance time series we distinguish (1) tube-fed activity (low radiance, <10 MW m² m^-1); (2) activity pauses (no radiance); (3) lava lake activity (low radiance, <5 MW m² m^-1); (4) short (<3 km long) flow extension (moderate radiance, 10-20 MW m² m ¹ ); and (5) 12 km long flow extension (high radiance, 15-30 MW m² m^-1). The ability of GOES to detect short-lived effusive events, coupled with the speed with which GOES-based hot spot information can be processed and disseminated, means that GOES offers a valuable additional volcano monitoring tool.     

Evaluation of the MODIS-Aqua Sea-Surface Temperature product in the inner and mid-shelves of southwest Buenos Aires Province,Argentina

Validation of sea-surface temperature (SST) provided by the MODIS-Aqua sensor (Moderate Resolution Imaging Spectroradiometer) for the inner and mid-shelves of the southwest of Buenos Aires Province (Argentina), is presented for the first time. In situ data obtained with a multi-parametric sonde YSI-6600 and a CTD SBE91 between 2002 and 2011 are used for comparison with the satellite SST product. The match-up exercise was established after comparing different spatial boxes, time difference windows, wind speeds, and also a coefficient of variation. The comparison exercise was made in the coastal zone and the rest of the inner and mid-shelves separately. In the coastal zone, applying a 3 × 2 pixel box and a time window of ±3 hours led to the most accurate results, with a coefficient of determination (R²) of 0.99, a bias of 0.62°C, and a root-mean-square-error (RMSE) of 0.79°C. In the inner-mid-shelves when applying a coefficient of variability <0.3, a time window of ±3 hours, and taking only values of wind speed > 6 m s^?1, R² is 0.97, bias is 0.46°C, and RMSE is 0.95°C. Wind speed plays a major role in the inner-mid-shelves as the SST product is affected by stratification and formation of a diurnal thermocline in the ‘skin and sub-skin layer’ when wind speed is below 6 m s^?1. The results for the two shelves are very similar. Finally, the spatial and temporal variability of the SST satellite product was analysed in the study area for the period August 2002–December 2010. The results show that inter-annual variability is not significant and that there is no positive or negative trend for the 9 years of the study. Seasonality is the main component of temporal variability, with variation in amplitude signal depending on bathymetry changes, physical forcing, stability of the water column, and presence of flood plains.     

Sensitivity of large-scale vegetation greenup and dormancy dates to climate change in the north−south transect of eastern China

Phenology event responses, based on vegetation types, are strong indicators of climate variability and the ability of the vegetation to adapt to future climate changes. However, the sensitivity of phenology events to climate change along either environmental or vegetation type gradients is rarely examined. Phenological curves of major vegetation types along the North?South Transect of Eastern China (NSTEC) have been developed using wavelet and smooth-spline methods based on the normalized difference vegetation index from 1982 to 2006. Spatial?temporal patterns, trends of greenup-onset dates, dormancy dates, and growing season lengths (GSLs) during the period of 1982?2006 are presented.

The greenup-onset dates were most significantly and negatively related to the temperature in cold and humid areas, but insignificantly and positively in semi-arid regions. However, dormancy date showed a positive correlation with temperature. In populations of the same vegetation type, distributed along thermal gradients of NSTEC, the phenology sensitivities to warming were different. Greenup sensitivities of cold temperate coniferous forest (CTCF) and temperate meadow steppe (TMS) increased significantly from??6.0 to 0 days °C^?1 (p < 0.001) and from about??2.0 to 2.0 days °C^?1 (p < 0.001), respectively. In contrast, temperate grass steppe (TGS) and temperate deciduous shrubland (TDS) showed a decreased trend of greenup sensitivity from 2.0 to??4.0 days °C^?1 (p < 0.001) and from 2.0 to??6.0 days °C^?1 (p < 0.001), respectively. For the dormancy date sensitivity, CTCF showed a decreasing trend from about 6.0 to 0 days °C^?1 (p < 0.001), and subtropical evergreen-broadleaved forest (SEBF) decreased from 5.0 to??5.0 days °C^?1 (p < 0.05).     

Mapping soil moisture in the central Ebro river valley (northeast Spain) with Landsat and NOAA satellite imagery: a comparison with meteorological data

This paper analyses and maps the spatial distribution of soil moisture using remote sensing: National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) and Landsat-Enhanced Thematic Mapper (ETM+) images. The study was carried out in the central Ebro river valley (northeast Spain), and examines the spatial relationships between the distribution of soil moisture and several meteorological and geographical variables following a long, intense dry period (winter 2000). Soil moisture estimates were obtained using thermal, visible and near-infrared data and by applying the ‘triangle method’, which describes relationships between surface temperature (T_s ) and fractional vegetation cover (F_r ). Low differences were found between the soil moisture estimates obtained using AVHRR and ETM+ sensors. Soil moisture estimated using remote sensing is close to estimations obtained from climate indices. This fact, and the high similarity between estimations of both sensors, suggests the reasonable reliability of soil moisture remote sensing estimations. Moreover, in estimations from both sensors the spatial distribution of soil moisture was largely accounted for by meteorological variables, mainly precipitation in the dry period. The results indicate the high reliability of remote sensing for determining areas affected by water deficits and for quantifying drought intensity.     

Use of portable ladders – field observations and self-reported safety performance in the cable TV industry

Abstract

Portable ladders incidents remain a major cause of falls from heights. This study reported field observations of environments, work conditions and safety behaviour involving portable ladders and their correlations with self-reported safety performance. Seventy-five professional installers of a company in the cable and other pay TV industry were observed for 320 ladder usages at their worksites. The participants also filled out a questionnaire to measure self-reported safety performance. Proper setup on slippery surfaces, correct method for ladder inclination setup and ladder secured at the bottom had the lowest compliance with best practices and training guidelines. The observation compliance score was found to have significant correlation with straight ladder inclined angle (Pearson’s r = 0.23, p < 0.0002) and employees’ self-reported safety participation (r = 0.29, p < 0.01). The results provide a broad perspective on employees’ safety compliance and identify areas for improving safety behaviours.

Practitioner Summary: A checklist was used while observing professional installers of a cable company for portable ladder usage at their worksites. Items that had the lowest compliance with best practices and training guidelines were identified. The results provide a broad perspective on employees’ safety compliance and identify areas for improving safety behaviours.     

Evaluation of a dynamic arm support for seated and standing tasks: a laboratory study of electromyography and subjective feedback

The goal of this study was to determine whether a new dynamic arm support system reduced shoulder and arm muscle load for seated and standing hand/arm tasks. The new system provides support for both horizontal and vertical arm motion. A total of 11 participants performed ten tasks (five seated and five standing) both with and without the arm support. Outcomes were assessed with electromyography and subjective feedback. Muscle activity was measured over the dominant side supraspinatus, triceps and forearm extensor muscles. Significant (p < 0.01) reductions in static muscle activity were observed in one of ten tasks performed with the support device for the supraspinatus muscle, in five tasks for the triceps and in one task for forearm extensor muscles. Likewise, a significant improvement in subjective measures was reported with the support device for ‘ease of task’ for two of ten tasks, for ‘forearm comfort’ for three of ten tasks and for ‘shoulder effort’ for six of ten tasks. The results suggest that a dynamic forearm support may improve subjective comfort and reduce static muscle loads in the upper extremity for tasks that involve horizontal movement of the arms. For rapid motions, the value of the support is limited due to internal inertia and friction.     

Design and evaluation of a curved computer keyboard

Conventional, straight keyboards remain the most popular design among keyboards sold and used with personal computers despite the biomechanical benefits offered by alternative keyboard designs. Some typists indicate that the daunting medical device-like appearance of these alternative ‘ergonomic’ keyboards is the reason for not purchasing an alternative keyboard design. The purpose of this research was to create a new computer keyboard that promoted more neutral postures in the wrist while maintaining the approachability and typing performance of a straight keyboard. The design process created a curved alphanumeric keyboard, designed to reduce ulnar deviation, and a built-in, padded wrist-rest to reduce wrist extension. Typing performance, wrist postures and perceptions of fatigue when using the new curved keyboard were compared to those when using a straight keyboard design. The curved keyboard reduced ulnar deviation by 2.2° ± 0.7 (p < 0.01). Relative to the straight keyboard without a built-in wrist-rest, the prototype curved keyboard with the built-in padded wrist-rest reduced wrist extension by 6.3° ± 1.2 (p < 0.01). There were no differences in typing speed or accuracy between keyboards. Perceived fatigue ratings were significantly lower in the hands, forearms and shoulders with the curved keyboard. The new curved keyboard achieved its design goal of reducing discomfort and promoting more neutral wrist postures while not compromising users' preferences and typing performance.     

What is the preferred number of consecutive night shifts? results from a crossover intervention study among police officers in Denmark

Among police officers in Denmark, we studied (i) how many consecutive night shifts participants preferred at baseline; (ii) preferences regarding three intervention conditions (two, four, and seven consecutive night shifts followed by the same number of days off/day shifts: ‘2 + 2’, ‘4 + 4’, ‘7 + 7’) at follow-up; (iii) characteristics of participants preferring each of these intervention conditions. Questionnaire data from a crossover intervention study were used (baseline: n = 73; follow-up: n = 68). At baseline, 49% preferred four consecutive night shifts. At follow-up, 57% preferred ‘4 + 4’, 26% preferred ‘2 + 2’ and 26% preferred ‘7 + 7’. Participants, who preferred longer spells of night work experienced that night work was less demanding, found it easier to sleep at different times of the day, and were more frequently evening types compared with participants who preferred shorter spells of night work. The participants’ preferences are likely to be influenced by their previous shift work experience.

Practitioner Summary: We investigated police officers’ preferences regarding the number of consecutive night shifts. The majority preferred four consecutive night shifts. Those who preferred the longer spells of night work found night work less demanding, found it easier to sleep at different times of the day, and were more frequently evening types.     

Development of real-time reference evapotranspiration at the regional scale using satellite-based observations

Real-time data of reference evapotranspiration (ET₀) at different space-time scales are essential to regional agricultural drought assessment, water accounting at the watershed to basin scale, and provide irrigation advisory to farmers. Here, we present a data-fusion approach that integrates satellite-based insolation product (8 km) from an Indian geostationary satellite (Kalpana-1) sensor (VHRR; Very High Resolution Radiometer) and high-resolution (~ 5 km) short-range weather forecast into an FAO56 model based on the classical Penman–Monteith (P-M) formulation. Five year (2009–2013) mean monthly estimates from the daily ET₀ product over the Indian landmass were found to vary between 10 and 350 mm. It increased from January to May (70–350 mm), followed by a decrease to reach the lowest in November (10–140 mm), thus typically showing unimodal distribution. The comparison of daily space-based and station-based estimates (at six ground stations) produced a root mean square deviation (RMSD) ranging from 21% to 38% for 977 paired data sets with the correlation coefficient (r) varying from 0.32 to 0.82. The error was reduced from 25% to 10% with an increase in ‘r’ from 0.43 to 0.98 for daily to 10 day summation period. Spatial grid-to-grid comparison of monthly ET₀ estimates with Global Data Assimilation System (GDAS) potential evapotranspiration (PET) showed RMSD within a range of 1.4–18.4% for most of the months, except for two. Further ET₀ analysis over normal and drought years showed that it could be used for comprehensive drought assessment with other existing indicators.     

Study of Electrical Conductance of Pressed Chemically Pure MnO2 Powder†

Variation of electrical conductance and capacity of chemically pure MnO₂ in pressed powder form under a stress 6·0 × 10¹¹ dynes/sq. cm has been studied within the temperature range 26^°c to 110^°c at 1 MC/s, Electrical conductance of samples in tablet, form (3 mm thick and 15 mm in diameter) was measured between 26^° C and 110^° before and after heat treatment at 300^°c for 36 hours. Capacitance values were also measured simultaneously within the above temperature range. Electrical conductance was found to attain a maximum at about 78^°c. There is a marked hysteresis in ‘; ln conductance’ ? 1 / T graph when measurements are made while temperature is rising and while falling.

Differential thermal analysis of the samo MnO₂ powder was also carried out. Measurements were made while heating and also while cooling. Two marked changes are clearly seen, one at mean temperature of 56^°c and the other at mean temperature of 80^°c, suggesting some second-order solid to solid phase changes at these temperatures. Corresponding breaks occur in the ‘ln conductance ’ ? 1/T and capacity-temperature graphs at the above-mentioned temperatures.     

The energetics of walking on sand and grass at various speeds

This study investigated the energetics of walking on sand and grass. Fourteen adult males, participated in the study. Participants had a mean age of 34.6 years old, 72.6 kg in mass and 172.5 cm in stature, who walked at 3, 4, 5, 6 and 7 km per h on sand and grass surfaces. Physiological measures included heart rate, O₂ uptake, CO₂ exhalation, ventilation and relative O₂ uptake using a MetaMax Ergospirometer. Speed was controlled in a methodology similar to the ‘Multistage 20-m Shuttle Run Test’. Data were collected during physiological steady rate at each determined speed. A minimum of 2 h rest was enforced between randomized conditions. Results indicate that there was a significant increase (p < 0.01) in all measured physiological indices indicative of energy expenditure when walking on sand compared to grass at 3–7 km per h, with the greatest disparity between the surfaces (ratio = 1.63) in relative O₂ consumption at 5 km per h.     

GeoEye-1 satellite versus ground-based multispectral data for estimating nitrogen status of turfgrasses

Satellite remote sensing of leaf nitrogen (N) content is an interesting technique for agricultural crops for both economic and environmental reasons since it allows the monitoring of fertilization, and hence can potentially reduce the application of N according to real plant needs. The objective of this trial was to compare the N status in different turfgrasses using both remote multispectral data acquired by GeoEye-1 satellite and two ground-based instruments. The study focused on creating a N content gradient on three warm-season turfgrasses, (Cynodon dactylon × transvaalensis ‘Patriot’, Paspalum vaginatum ‘Salam’, Zoysia matrella ‘Zeon’), and two cool-season (Festuca arundinacea ‘Grande’, Lolium perenne ‘Regal 5’). The linear gradient of applied N ranged from 0 to 342 kg ha^?1 for the warm-season and from 0 to 190 kg ha^?1 for the cool-season turfgrasses. Proximity and remote-sensed reflectance measurements were acquired and used to determine the normalized difference vegetation index (NDVI). Our results proved that proximity-sensed NDVI is highly correlated with data acquired from satellite imagery. The correlation coefficients between data from the satellite and the other sensors ranged from 0.90 to 0.99 for the warm-season and from 0.83 to 0.97 for the cool-season species. ‘Patriot’ had a clippings N content ranging from 1.20% to 4.1%, thus emerging as the most reactive species to N fertilization. As such, the GeoEye-1 satellite can adequately assess the N status of different turfgrass species and its spatial variability within a field, depending on the N rates applied. In future, information obtained from satellites could allow precision fertilizer management on sports fields, golf courses, or other extended green areas.