Effect of vibrating steering on grip strength in heavy vehicle drivers.

The grip strength in both hands of thirty-two heavy vehicle drivers and twenty-two nondrivers ranging from 30 to 60 years of age was investigated. Blood pressure, heart rate and other physical parameters were also investigated. The subjects were drawn at random from the employees of the North Bengal State Transport Corporation and Civil Aviation. Heavy vehicle drivers perform their duties 8 hr per day with an average speed of 60-70 km hour for 4-5 hr of continuous driving at a time. The only significant difference in the physical characteristics of heavy vehicle drivers and nondrivers was their body weight (p less than 0.05). The right and left wrist power of heavy vehicle drivers was respectively 6% and 3% higher than that of nondrivers. The mean blood pressure, heart rate and wrist width were found to be almost same in heavy vehicle drivers and nondrivers. From our studies we concluded that vibrating steering probably has no influence on the grip strength and that performing 8 hr of driving daily does not affect the blood pressure and heart rate in heavy vehicle drivers. However, further studies are needed to determine the influence of vibrating steering on grip strength.     

Long-term survey data (1965-1972) on the occurrence of Anisakis larvae (Nematoda: Ascaridida) in herring, Clupea harengus L., from the North Sea

The occurrence of larval Anisakis in North Sea herring was examined during the period 1965-1972 using a sampling method which yielded comparable data for all eight years. Data on abundance of infestation in several herring stocks pointed to remarkable fluctuations over the study period with an increase in the period 1966-1968 followed by a decrease in the period 1968-1972. Of various hypotheses that may explain this situation, it is concluded that changes in the migration behaviour of the herring may be responsible. Other data and statistics are discussed with special reference to variations in infestation level in different samples and to the occurrence of adult nematodes in marine mammals.     

Psychophysiological reactivity of aggressive drivers: an exploratory study

In the United States, motor vehicle accidents are the leading cause of accidental death and injury. Aggressive driving, which has been identified as a major risk factor for motor vehicle accidents by transportation authorities, is thus an important topic of study. This study compared the physiological reactivity of self-referred aggressive and nonaggressive drivers. Heart rate, blood pressure, facial muscle activity, and skin resistance were monitored as participants listened to idiosyncratic vignettes of driving and fear-provoking scenarios, as well as during a standard stressor task (mental arithmetic). The results were that aggressive drivers exhibited significant increases in muscle tension and blood pressure during the driving vignettes, relative to controls. They also responded to the fear vignette and mental arithmetic in a qualitatively different fashion from that of controls. The aggressive drivers responded to these stimuli with less overall heart rate and electrodermal reactivity, but increased blood pressure and muscle tension. In contrast, the controls responded to the fear vignette and mental arithmetic primarily with increased heart rates and decreased skin resistance. The findings suggest that both physiological hyperarousal as well as differential responses to stressful stimuli may contribute to aggressive driving. Implications for interventions with this population are discussed.     

Driving and subsidiary behavior of taxi drivers working alternate-day shifts.

A field study on taxi drivers working alternate-day shifts of prescribed duration of 16 hr of work revealed that most of them actually worked longer for 16 hr 50 min on the average, starting from 7:00 and ending later than 2:00. The mean hourly income greatly increased in hours later than 22:00 due to the increased fare per hire and higher speed, so that these hours were regarded by the drivers as the most important period of the day. This resulted in retarded mean bedtime of 5:31 after the shift end and in reduced sleep. The total rate of subsidiary activities of the drivers decreased during the middle of the day, but increased towards the shift end. Those activities having a relatively low rate at the beginning, such as subsidiary lower limb movements, shoulder-neck movements, and yawning, remarkably increased in the late evening and midnight hours. These activities increased even during frequent driving operations and tended to relate with each other, often recurring in bursts especially while feeling drowsy. The incentive wage system of the drivers thus accounts not only for the extraordinarily long working hours but also for intensified night work.     

Effect of inspiratory resistance to prolonged exercise in a hot environment wearing protective clothing

The effects of inspiratory resistance on prolonged work in a hot environment wearing a nuclear, bacteriological and chemical warfare (NBCW) mask and overgarment were assessed in 10 males. Subjects walked on a treadmill at 5 km/hr, 2% gradient, until their core temperature reached 39° C or for a duration of 90 min. Rectal temperature, heart rate, ventilation, oxygen consumption and rate of perceived breathing were measured. There were no differences between break-point time without the canister (62.2 ± 21 min) and with the canister (58.9 ± 17 min). Regression analysis indicated that the mean core temperature increased by 0.02° C for every minute of work performed and heart rate by 6 beats/min for every increase of 0.2° C in core temperature. Reduction in heat transfer brought about by wearing the protective overgarment and mask with or without the canister will significantly increase core temperature and limit the performance of moderate work to approximately 1 h in a moderately fit individual.     

Further studies on the E blood group system in pigs

The blood group system E in pigs is similar to the B system in cattle, one of the most complicated of the hitherto known blood group systems.
Studies of Andresen (1957), Saison (1958), Andresen & Wroblewski (1959), Andresen et al. (1959), Andresen (1962, 1965), Rasmusen (1965), Hojný et al. (1966), Dinklage et al. (1966), Dinklage & Major (1968), Hradecký & Hojný (1972), Hojný & Hradeck (1972, 1973) lead to the determination of the various E alleles.
This report presents information of a new blood group factor E_p in pigs.     

The Influences of Seasonal Changes in Solar Radiation and Air Temperature on the Growth in the Early Vegetative Phase of Zea mays

At weekly intervals from May to September over 2 years the growthof separate batches of Zea mays (Swiss hybrid Orla 266) wasrecorded for individual plants in pot experiments, togetherwith the corresponding weekly means of solar radiation and themean, maximum, and minimum diurnal air temperatures. To reducesampling errors the plants were ranked on the bases of initialgrain size and leaf number. To minimize differences in stageof development at the end of 21 days from sowing the size wasadjusted in 1965 by switching the pots in and out of a glasshouse:in 1966 the plants were kept for the first 11 days in a controlledenvironment and then hardened off in the open. Between 21 and28 days when the second sample was taken half the plants weresubjected to light shade (0.65–0.70 daylight). Multiple regression analysis showed that the relative growthrate of the whole plant (RGR), the rate of increase in leafarea (RLGR), and the net assimilation rate (NAR) were positivelydependent on both radiation and mean air temperature. In 1965there were negative effects of minimum temperature on RGR andNAR and a positive response of RLGR to leaf number. In 1966an increase in leaf number led to a higher RGR and LAR but depressedRLGR, while minimal temperature had no significant effects.In all these regressions the variation accounted for was high,ranging from 80 to 89 per cent. At the second sampling occasion the leaf-area ratio (LAR_f) wasinversely related to radiation, negatively dependent on daytemperature, but positively linked with night temperature. Theorder of the initial LAR exerted no influence. The RGRs of theshoot and the root were positively associated with both radiationand mean temperature. In 1965 there were small negative responsesof the shoot to both minimum temperature and leaf number andfor the root only leaf number. The variation accounted for wasleast for LAR_f (59–62 per cent) and intermediate for RGR_aand RGR_r (77–89 per cent). For RGR, NAR, and RLGR the calculated partial regression coefficientsfor mean temperature in 1965 were larger than those for radiationbut in 1966, apart from RLGR, they were equalled by radiation.The discrepancies between years can be ascribed to a highercorrelation coefficient between radiation and temperature in1965 (0.53) as against 1966 (0.33). The value of multiple regression analysis in the evaluationof the environment by carefully designed field experiments isemphasized in relation to other investigations of light andtemperature undertaken under controlled conditions.     

Variation in chemical composition of the River Frome, England, from 1965 to 1972

This study covers a 7-year period from 1965 to 1972, and shows the variation in flow, water chemistry and throughput of nutrients. The annual discharge of the River Frome varied considerably from year to year, ranging from a mean value of 4.48 m³ sec⁻¹ in 1971 to one of 8.38 m³ sec⁻¹ in 1966. The mean annual nutrient losses calculated over all 7 years of study from the River Frome catchment were: Nitrate 11.4 kg ha⁻¹, phosphorus 0.49 kg ha⁻¹ and potassium 8.4 kg ha⁻¹. There has been an increase in annual throughput (in years of similar flow) of 21% in phosphate and 41% in nitrate from 1965 to 1972.     

An unexpected role for visual feedback in vehicle steering control

Some motor tasks can be completed, quite literally, with our eyes shut. Most people can touch their nose without looking or reach for an object after only a brief glance at its location. This distinction leads to one of the defining questions of movement control: is information gleaned prior to starting the movement sufficient to complete the task (open loop), or is feedback about the progress of the movement required (closed loop)? One task that has commanded considerable interest in the literature over the years is that of steering a vehicle, in particular lane-correction and lane-changing tasks. Recent work has suggested that this type of task can proceed in a fundamentally open loop manner, with feedback mainly serving to correct minor, accumulating errors. This paper reevaluates the conclusions of these studies by conducting a new set of experiments in a driving simulator. We demonstrate that, in fact, drivers rely on regular visual feedback, even during the well-practiced steering task of lane changing. Without feedback, drivers fail to initiate the return phase of the maneuver, resulting in systematic errors in final heading. The results provide new insight into the control of vehicle heading, suggesting that drivers employ a simple policy of "turn and see," with only limited understanding of the relationship between steering angle and vehicle heading.     

Performance enhancement in rally car drivers via heat acclimation and race simulation

To investigate the combined use of an interactive racecar simulator and heat acclimation on psychomotor (driving) performance, eight rally drivers underwent 4 days of repeated heat (50 degrees C) exposure (1 h x day(-1)) during which they performed a simulated rally drive (3x12-min stages each separated by a 2-min break), after first cycling for 15 min at 125 W to induce some degree of fatigue and heat storage prior to beginning the rally. During the rally stages, a generic set of pace notes were read to the subject by a co-driver. In each simulation, sweat loss, heart rate, core (rectal) and skin temperatures were recorded and driving and psychomotor performance were assessed by recording stage times and time to complete a psychomotor test. Levels of physiological and perceived thermal strain were also recorded. Significant decreases in rally stage times (88 s; P<0.005), psychomotor test time (18 s; P<0.01), final core (0.25 degrees C; P<0.001) and skin (0.44 degrees C; P<0.005) temperatures, heart rate (16 beats x min(-1); P<0.05) and physiological (15 W x m(-2); P<0.005) and perceived thermal (3.7 units; P<0.01) strain were evident by the end of the final simulation, and a significant (P<0.05) increase in sweat sensitivity (+0.33 g x h(-1) x degrees C(-1)) was also recorded. These results suggest that both heat acclimation and race simulation can improve the psychomotor performance of rally drivers, although the relative contribution of each factor was not determined here. However, in a practical setting, these factors would not be used in isolation. After performing the acclimation and simulation protocol prior to an actual rally, drivers subjectively reported improvements in tolerating a high thermal load and in their ability to control the rally vehicle.     

Coronary heart diseases: Assessment of risk associated with work exposure to ultralow-frequency magnetic fields

The present analysis was stimulated by previous findings on the possible influence of natural ultralow-frequency (ULF; 0.001–10 Hz) geomagnetic field variations on the cardiovascular system and indications of an effect of man-made ULF magnetic fields on the rate of myocardial infarction. In the present study, we considered the occupational health hazards of the strongest ULF magnetic fields in densely populated urban areas. Measurements of ULF magnetic field fluctuations produced by trains powered by DC electricity were performed by means of a computer-based, highly sensitive, three-component magnetometer. We found that the magnitude of magnetic field pulses inside the driver's cab of electric locomotives (ELs) could be ≥ 280 μT in the horizontal component perpendicular to the rails and up to approximately 130 μT in the vertical component, and, in the driver's compartment of electric motor unit (EMU) trains, they were approximately 50 and 35 μT, respectively. We have investigated the relationships between the occupational exposure to ULF magnetic field fluctuations produced by electric trains and cardiovascular diseases (CVDs) among railroad workers in the former Soviet Union. We have analyzed medical statistical data for a period of 3 years for approximately 45,000 railroad workers and 4,000 engine drivers. We have also analyzed 3 years of morbidity data for three subgroups of engine drivers (∼4,000 in each group) operating different types of trains. We find that EL drivers have a twofold increase in risk (2.00 ± 0.27) of coronary heart diseases (CHDs) compared with EMU drivers. Because our analysis of major CVDs shows that the examined subpopulations of drivers can be considered to have had equal exposure to all known risk factors, the elevated CHD risk among EL drivers could be attributed to the increased occupational exposure to ULF magnetic fields. © 1996 Wiley-Liss, Inc.     

Cardiac vagal modulation of heart rate during prolonged submaximal exercise in animals with healed myocardial infarctions: effects of training

The present study investigated the effects of long-duration exercise on heart rate variability [as a marker of cardiac vagal tone (VT)]. Heart rate variability (time series analysis) was measured in mongrel dogs (n = 24) with healed myocardial infarctions during 1 h of submaximal exercise (treadmill running at 6.4 km/h at 10% grade). Long-duration exercise provoked a significant (ANOVA, all P < 0.01, means +/- SD) increase in heart rate (1st min, 165.3 +/- 15.6 vs. last min, 197.5 +/- 21.5 beats/min) and significant reductions in high frequency (0.24 to 1.04 Hz) power (VT: 1st min, 3.7 +/- 1.5 vs. last min, 1.0 +/- 0.9 ln ms(2)), R-R interval range (1st min, 107.9 +/- 38.3 vs. last min, 28.8 +/- 13.2 ms), and R-R interval SD (1st min, 24.3 +/- 7.7 vs. last min 6.3 +/- 1.7 ms). Because endurance exercise training can increase cardiac vagal regulation, the studies were repeated after either a 10-wk exercise training (n = 9) or a 10-wk sedentary period (n = 7). After training was completed, long-duration exercise elicited smaller increases in heart rate (pretraining: 1st min, 156.0 +/- 13.8 vs. last min, 189.6 +/- 21.9 beats/min; and posttraining: 1st min, 149.8 +/- 14.6 vs. last min, 172.7 +/- 8.8 beats/min) and smaller reductions in heart rate variability (e.g., VT, pretraining: 1st min, 4.2 +/- 1.7 vs. last min, 0.9 +/- 1.1 ln ms(2); and posttraining: 1st min, 4.8 +/- 1.1 vs. last min, 2.0 +/- 0.6 ln ms(2)). The response to long-duration exercise did not change in the sedentary animals. Thus the heart rate increase that accompanies long-duration exercise results, at least in part, from reductions in cardiac vagal regulation. Furthermore, exercise training attenuated these exercise-induced reductions in heart rate variability, suggesting maintenance of a higher cardiac vagal activity during exercise in the trained state.     

Winter-spring sport fishery in the heated discharge of a nuclear power plant

A substantial winter-spring sport fishery has developed along the 1.83 km heated discharge canal of a nuclear power plant. An estimated 3166 fishermen caught an estimated 11 090 fish, representing 18 species, during a creel survey conducted from January through June, 1972. Eighty-seven per cent of the canal fishermen were successful in catching one or more fish, and averaged 2.07 fish per rod-hour of effort. Fishermen averaged 1.08 fish per rod-hour and had a 61 % success rate at other areas in the vicinity of the plant from April through November, 1965–1969. There was a correlation between the water temperature of the canal and the number of fish caught per rod-hour of effort.     

Effect of red and far-red illuminations at the end of short days and their interaction with night-break illuminations, on flowering of Chrysanthemum morifolium plants

Flowering of chrysanthemum plants grown for 8 hr in sunlightwas delayed by 20 min of FR given prior to 16 hr dark periods.These FR illuminations increased the inhibition caused by thresholdamounts of night-break illuminations. On the other hand, 20min of R at the start of the dark period alleviated some ofthe inhibitory effects of the threshold of night-break illuminations. ¹Contribution from The Volcani Center, Agricultural ResearchOrganization, Bet Dagan, Israel, 1972 Series No. 2184 E. (Received August 26, 1972; )     

Carnitine worsens both injury and recovery of contractile function after transient ischemia in perfused rat heart

While carnitine overload appears to have therapeutic effects in pathological situations such as heart recovery after ischemia, its benefits as dietary supplementation for aerobic exercise have been questioned. We studied the effect of carnitine supplementation on the response of perfused rat heart to ischemia and reperfusion. Supplementation of the perfusion medium with 1 mM carnitine had no effect on cardiac performance in normoxic hearts, although it lowered lactate production by nearly 80%. Carnitine did not affect the amount of lactate accumulated during 30 min of ischemia, which was recovered in the perfusate immediately after reperfusion. However, carnitine worsened tissue injury, as shown by the 70% increase in creatine kinase release. Carnitine also worsened the recovery of contractile function, as revealed by the slower increase in heart rate and contractile force. In addition, carnitine supplementation increased contracture of the heart shortly after reperfusion. Therefore, in conditions where it does not increase glucose oxidation, carnitine supplementation worsens both injury and recovery of contractile function after transient ischemia in perfused rat heart.     

The effect of weather on the concentration of pollen within sugar-beet seed crops

The concentration of pollen in the air within diploid open-pollinated sugar-beet seed crops at Broom's Barn Experimental Station increased between 05.00 and 09.00 G.M.T. as relative humidity became less than 90%, was greatest between 09.00 and 11.00, when relative humidity was c. 75%, and gradually decreased towards evening. The average pollen concentration during 24 h periods ranged from 170 to 12400/m³ being greatest on fine, windy, dry days after periods of cooler weather. Rain during the morning washed pollen out of the air and damaged developing anthers, but rain in the late afternoon following a sunny morning seemed hardly to affect the pollen catch, while rain at night sometimes caused an immediate temporary increase in pollen concentration. Most pollen was released between 27 June and 31 July in all years (1965-7); more in the first than in the second half of July. 1965 was cool and damp, 1967 warm and dry, 1966 warm and dry early, and cool and wet late. The total pollen catch in 1965 was 83% and in 1966 31% of that in 1967 but the percentage germination of seed harvested in the 3 years was similar. The total pollen catch on a trap 230 m east of the 1965 crop was c. 1% of the catch within the crop on days with gusty westerly winds and the catch on a trap c. 46 cm above the 1966 crop averaged 78.6% of that at the level of most flowers.     

Predation Risk Drives Habitat‐Specific Sex Ratio in a Monomorphic Species,the Brown Hare (Lepus europaeus)

In dimorphic species, sexual habitat segregation is generally explained by the differences in nutritional needs or by a trade‐off between fulfilling food requirements and avoiding predation. However, it remains unclear whether predation risk is strong enough to drive the differences in habitat use between sexes as predicted by the predation sensitivity hypothesis. Here we test in a monomorphic species, the brown hare (Lepus europaeus), the prediction that abundance of the gender more sensitive to predation is higher in safer habitat. We used data on 1645 individually marked hares in western Poland during autumn–winter seasons of 1966/1967–1978/1979 to estimate sex‐specific annual survival rates. We analyzed the stomach contents of 134 foxes shot in 1965/1966–1994/1995 to evaluate fox predation on hares. Finally, we employed data on 26 790 hares live‐trapped in 1965/1966–1994/1995 to analyze hare sex ratio across habitats. We found that male annual survival rate was lower than that of females and that the predation risk by foxes on hares was lower in agricultural than forest habitat. Our finding, that males were more often trapped by nets in agricultural than the forest habitat, provides indirect evidence for the predation sensitivity hypothesis. We conclude that predation risk can be a driving force for habitat‐specific sex ratio in a monomorphic species such as the brown hare.     

Leukoaraiosis Significantly Worsens Driving Performance of Ordinary Older Drivers

Background

Leukoaraiosis is defined as extracellular space caused mainly by atherosclerotic or demyelinated changes in the brain tissue and is commonly found in the brains of healthy older people. A significant association between leukoaraiosis and traffic crashes was reported in our previous study; however, the reason for this is still unclear.

Method

This paper presents a comprehensive evaluation of driving performance in ordinary older drivers with leukoaraiosis. First, the degree of leukoaraiosis was examined in 33 participants, who underwent an actual-vehicle driving examination on a standard driving course, and a driver skill rating was also collected while the driver carried out a paced auditory serial addition test, which is a calculating task given verbally. At the same time, a steering entropy method was used to estimate steering operation performance.

Results

The experimental results indicated that a normal older driver with leukoaraiosis was readily affected by external disturbances and made more operation errors and steered less smoothly than one without leukoaraiosis during driving; at the same time, their steering skill significantly deteriorated.

Conclusions

Leukoaraiosis worsens the driving performance of older drivers because of their increased vulnerability to distraction.     

Cardiovascular effects of intravenous and intracoronary administration of atrial natriuretic peptide in halothane anesthetized dogs

Cardiovascular actions of synthetic 1-28 human natriuretic peptides (hANP) were examined in dogs anesthetized with halothane. In seven closed-chest dogs a Swan-Ganz catheter was inserted for measurement of cardiac output. Intravenous infusion of increasing doses of hANP (0.1, 0.3, 0.9 microgram/kg/min) lowered mean aortic pressure without affecting heart rate significantly. Cardiac output and pulmonary wedge pressure were markedly decreased while total peripheral resistance was increased significantly. All these parameters returned to control levels after 1 hr of recovery with an 100-150ml of saline infusion to increase pulmonary capillary wedge pressure to the preinfusion value. Intracoronary infusion of hANP (0.05 and 0.1 microgram/kg/min) did not cause any significant changes in coronary flow and regional contraction. These results indicate that the hypotensive action of hANP is due to a decrease in cardiac output mediated by reduced preload but not by negative inotropic action.     

Measurements of volume changes and venous pressure in the human lower leg during walking and running.

This study investigates whether walking or running prevents the formation of edema in the lower leg. In 18 volunteers changes in calf volume were measured using strain gauge plethysmography during slow (3 km/h) and fast (6 km/h) walking or running (10 km/h) on a treadmill for 20 min each. Venous pressure was measured in a superficial vein near the ankle. Low-pass filtering removed motion artifacts from the signals. Slow walking reduced the calf volume in a biphasic manner: a rapid decrease was followed by a slow decline, lasting from about minute 2 to minute 20, its mean rate being -0.073%/min. Besides a rapid initial decrease, no significant change was observed during fast walking. During running, the calf volume first increased within 7 min to a maximum of 2.5% and subsequently decreased with a mean rate of -0.096%/min. The medians of venous pressure were 84.0, 23.5, 30.4, and 29.5 mmHg during quiet standing, slow and fast walking, and running, respectively. The experimental results prove the hypothesis that walking prevents dependent edema formation. This effect, however, cannot be fully explained by the lowered venous pressures.