Nocturnal Conditions Research Articles

Effects of Different Sleeping Postures on Intraocular Pressure and Ocular Perfusion Pressure in Healthy Young Subjects

To investigate the effects of different sleeping positions of head and body on intraocular pressure (IOP) and ocular perfusion pressure (OPP) in healthy, young subjects. Prospective, comparative case series. Twenty healthy young Korean subjects. We measured IOP and blood pressure (BP) with the subjects seated and recumbent, including supine, right lateral decubitus, left lateral decubitus, prone with right head turn, and prone with left head turn positions. We measured IOP using an Icare tonometer in both eyes 5 minutes after assuming each position in a randomized sequence. We calculated the OPP using the formulas based on the mean BP adjusted for the height of the eye over the heart. The eye on the lower side in the lateral decubitus or prone with head turn position was termed the dependent eye. Difference in IOP and OPP of the dependent and nondependent eyes during changes of sleeping positions of body and head. Mean IOP of right and left eyes while sitting was significantly lower than that measured in each recumbent position (all P<0.001). The OPPs in both eyes were significantly higher in all recumbent positions than in a sitting position (all P<0.001). Mean IOP of the dependent eyes was higher than that of the nondependent eyes in the lateral decubitus positions and in the prone positions with head turns (all P<0.001). No significant intereye difference in OPP was found for any position. Among IOPs measured in the recumbent positions, mean IOP of the dependent eye in the lateral decubitus position or in the prone position with head turn was significantly higher than that of the ipsilateral eye in the supine position (all P<0.0001). All sleeping positions of head and body resulted in an elevation of IOP and an increase in the calculated OPP compared with the sitting position in healthy, young subjects. The postural change from supine to lateral decubitus or prone with head turn position increased the IOP of the dependent eyes without significant alteration in OPP in healthy awake subjects. Further research is needed under nocturnal conditions in a sleep laboratory. The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Strong similarities between night-time deposition velocities of carbonyl sulphide and molecular hydrogen inferred from semi-continuous atmospheric observations in Gif-sur-Yvette, Paris region

We investigated the diurnal variations of atmospheric carbonyl sulphide (COS) during 2011 at Gif-sur-Yvette, a suburban atmospheric measurement site in France. These data were collected semi-continuously in parallel with hydrogen (H2), carbon monoxide (CO) and 222Radon (222Rn) measurements. Fluxes and deposition velocities were calculated for nocturnal situations of low boundary layer height using the Radon-Tracer Method. Contrary to CO and H2, the diurnal cycles of COS are not impacted by emissions from nearby automobile traffic. In the absence of local anthropogenic combustion sources, COS and H2 mole fractions generally show similar temporal variations with night-time depletion coinciding with 222Rn accumulation during stable nocturnal conditions. Nocturnal COS deposition velocities range from 0.07 to 0.40 mm s−1, with an annual mean of 0.18±0.12 mm s−1 (n=14). We found strong similarities between COS and H2 dry deposition velocities in terms of annual mean and ranges of variation, and data showed linear correlation between the two. This study provides new evidence of the loss of COS near the ground via non-photosynthetic processes. Although the dominant sink of atmospheric H2 is diffusion and subsequent destruction in soils, it is not all certain that COS is taken up at night solely by soils.

Estimation of frost occurrence and duration of frost for a short-grass surface

The estimation of frost duration (FD) was investigated using dielectric, infrared surface temperature and grass temperature subhourly measurements. Near real-time FD data and information displays and alerts were also made available via a web-based system. FD was estimated using a dielectric leaf wetness sensor (LWS) method, for which the sensor voltage was between 274 and 284 mV with a voltage rate of change less than 10 mV h−1 for a 4 min period, and two temperature methods for which infrared thermometer (IRT) and grass temperatures were compared with 0 °C. FD estimation using the LWS method ensured that most of the transitional dry-to-wet and wet-to-dry events were not included in the FD count. Generally, the IRT method yielded the largest estimate of FD, grass temperature method lower and LWS method lowest. Micrometeorological measurements showed consistent air temperature gradients of 2.25 °C m−1 for cloudless nocturnal frosted conditions with few air temperature measurements at 1 m and none above indicating frost occurrence. At the very least, automatic weather station systems should contain a grass thermometer or preferably an IRT for determination of FD with near real-time data and graphics displayed, including timeous alerts of frost occurrence and FD, using the Internet.

Influence of photoperiod on carbon dioxide and methane emissions from two pilot-scale stabilization ponds

Greenhouse gas (GHG) emissions (CO(2), CH(4)) from pilot-scale algal and duckweed-based ponds (ABP and DBP) were measured using the static chamber methodology. Daylight and nocturnal variations of GHG and wastewater characteristics (e.g. chemical oxygen demand (COD), pH) were determined via sampling campaigns during midday (12:30-15:30) and midnight (00:30-03:30) periods. The results showed that under daylight conditions in ABP median emissions were -232 mg CO(2) m(-2) d(-1) and 9.9 mg CH(4) m(-2) d(-1), and in DBP median emissions were -1,654.5 mg CO(2) m(-2) d(-1) and 71.4 mg CH(4) m(-2) d(-1), respectively. During nocturnal conditions ABP median emissions were 3,949.9 mg CO(2) m(-2) d(-1), 12.7 mg CH(4) m(-2) d(-1), and DBP median emissions were 5,116 mg CO(2) m(-2) d(-1), 195.2 mg CH(4) m(-2) d(-1), respectively. Once data measured during daylight were averaged together with nocturnal data the median emissions for ABP were 1,566.8 mg CO(2) m(-2) d(-1) and 72.1 mg CH(4) m(-2) d(-1), whilst for DBP they were 3,016.9 mg CO(2) m(-2) d(-) and 178.9 mg CH(4) m(-2) d(-1), respectively. These figures suggest that there were significant differences between CO(2) emissions measured during daylight and nocturnal periods (p < 0.05). This shows a sink-like behaviour for both ABP and DBP in the presence of solar light, which indicates the influence of photosynthesis in CO(2) emissions. On the other hand, the fluxes of CH(4) indicated that DBP and ABP behave as net sources of CH(4) during day and night, although higher emissions were observed from DBP. Overall, according to the compound average (daylight and nocturnal emissions) both ABP and DBP systems might be considered as net sources of GHG.

Evaluation of a Closed Tunnel for Field‐Scale Measurements of Nitrous Oxide Fluxes from an Unfertilized Grassland Soil

Emissions of the major greenhouse gas NO from soils are characterized by huge spatial variability. An upscaling based on conventional small-scale chamber measurements is thus questionable and may involve a considerable amount of uncertainty. In this feasibility study, we evaluated the applicability of a large, closed tunnel for field-scale measurements of NO fluxes from an unfertilized grassland soil. The tunnel, coupled to an open-path Fourier transform infrared spectrometer, covered 500 m. During a 2-yr campaign, concurrent closed-chamber measurements (area of 0.045 m) were performed at the tunnel plot. The tunnel system enabled high-density and precise NO concentration measurements under dry, stable, nocturnal atmospheric conditions, but higher wind speeds and rain limited its application. To calculate an unbiased, predeployment NO flux from the increase of NO concentrations during tunnel deployment, we propose a novel approach based on inverse modeling (IMQ0). We show that IMQ0 is appropriate for the specific non-steady state tunnel setup. Compared with conventional models, which were developed for gas flux calculation from concentration gradients measured in vented closed chambers, IMQ0 is most accurate. Whereas NO fluxes obtained from the tunnel measurements were generally small and at a typical background level, the chamber measurements revealed high spatial and temporal variability of NO emissions, including slight NO uptake and precipitation-triggered emission peaks. The cumulative NO fluxes of both methods differed by one order of magnitude and were smaller for the tunnel measurements. We argue that the chambers were occasionally susceptible to detection of hotspots and hot moments of NO emission. However, these emissions were evidently not representative for the field scale. Compared with available greenhouse gas measurement techniques, we conclude that the tunnel may serve as a gap-filling method between small-scale chamber and ecosystem-level micrometeorological techniques, particularly during stable nocturnal conditions.

Simulation study of the large-scale modification of the mid-latitude F-layer by HF radio waves with different powers

Abstract. A mathematical model of the ionosphere, developed earlier, is applied to investigate the large-scale mid-latitude F-layer modification by HF radio waves with different powers. Simulations are performed for the point with geographic coordinates of the "Sura" heating facility (Nizhny Novgorod, Russia) for autumn conditions. The calculations are made for distinct cases, in which the effective absorbed power has different values belonging to the 5–100 MW range, both for nocturnal and daytime conditions. The frequency of powerful HF waves is chosen to be close to the most effective frequency for the large-scale F2-layer modification. The results of modeling indicate that the effective absorbed power can influence considerably the F-layer response to high-power radio waves in the mid-latitude ionosphere.

Anthropogenic radiative forcing of marine stratocumulus clouds under different thermodynamic conditions—An LES model study

A LES model with bin microphysics was used to investigate the aerosol indirect effects of marine stratocumulus clouds that develop under different thermodynamic conditions. The diurnal contrasts of cloud development were also examined in detail. Three observed CCN spectra that represent maritime, continental and polluted air masses were used as input CCN spectra. Two observed thermodynamic soundings and two derived ones from the observed soundings to vary the inversion altitude were used as initial thermodynamic conditions. With these initial conditions the model was run for the daytime and nocturnal conditions to make the total number of model runs to be 24. For both daytime and nocturnal conditions, the cloud depth and liquid water path (LWP) varied with the thermodynamic soundings. For a given thermodynamic sounding, LWP tended to be similar or slightly smaller for polluted. However, cloud top radiative cooling is stronger for polluted due to smaller sizes of cloud droplets and therefore turbulent mixing is stronger for polluted. However, there were significant differences in LWP between the daytime and nocturnal clouds. For the daytime condition, the cloud became decoupled from the surface layer and moisture supply was limited for all soundings. In contrast, with the absence of solar radiation, cloud top radiative cooling was much stronger, turbulent mixing was also much stronger and therefore no decoupling occurred and clouds were thicker with greater LWP in the nocturnal runs. To note is the derived thermodynamic sounding (named MH) that produced the thickest clouds: the clouds were too thick to be maintained as a single layer cloud and became multi-layered for the daytime condition while the maritime stratocumulus cloud broke up into a cumuliform cloud due to heavy drizzle for the nocturnal condition. From the daytime run results, the anthropogenic cloud radiative forcing was calculated by subtracting the net cloud radiative forcing for maritime from that for polluted. It amounted to be −21.6Wm−2 for MH but was more than a factor of two larger for all three other soundings, −56.4, −55.4 and −55.7Wm−2. For the MH sounding, the LWP was noticeably smaller for polluted than for maritime, the relative difference of the effective radii between maritime and polluted was small and therefore albedo difference between the two was also small, compared to those for the other three soundings. Notable is the similar magnitude of the anthropogenic cloud radiative forcing for these three soundings despite the significant differences in cloud depths among the clouds produced by these soundings. This may imply that there may be an optimal range of cloud depth that can produce a strong anthropogenic cloud radiative forcing. The cloud depths were smaller than 150m for the thermodynamic sounding that produced the shallowest clouds but it seemed to be within the optimal range.

Altered Prey Responses in Round Goby from Contaminated Sites

Although prey must move to forage, escape predation or gain information about predation risk, movement itself enhances the risk of predation by increasing visibility of prey and encounter rates with predators. Animals subjected to stressors often show altered behaviour; a widely cited effect of contaminant exposure is an increase in vulnerability to predation, which may be mediated by an increase in risky behaviour. Round goby are invasive fish that typically rely on crypsis and sheltering (low-activity behaviours) to avoid predators. We collected round goby from contaminated sites and tested whether they showed signs of altered risk-taking compared with fish from a less contaminated reference site. We subjected the fish to a simulated predation event (a motor-operated model bass) under both diurnal and nocturnal conditions. Fish from contaminated sites showed lower overall activity levels, but also failed to reduce activity following an attack, unlike fish from the reference site. The intensity of effects varied with diel period. Males, but not females, from contaminated sites showed reduced likelihood of darting during an attack, while females, but not males, from contaminated sites were less likely to approach the predator. Sex differences in round goby risk-taking may reflect sex-specific selection pressures on activities promoting predation risk. With the exception of post-attack activity, round goby from contaminated sites generally showed signs of reduced risk-taking. If contaminant exposure increases goby vulnerability to predators, it may be occurring through behavioural mechanisms other than impacts on risky prey responses.

Observed Characteristics of the Afternoon–Evening Boundary Layer Transition Based on Sodar and Surface Data

AbstractThe early-evening boundary layer transition has been defined in the past using a variety of criteria, the most popular of which is the onset of a negative surface heat flux. According to this definition, the transition is an almost-instantaneous event that occurs when the positive daytime heat flux switches to the negative nighttime heat flux. This definition is simplistic, however, because the stable boundary layer does not form instantaneously over a deep layer. Other factors are involved, and many changes occur aloft during the transition period that this definition does not account for—for example, a more gradual reduction in turbulence and an increase in wind speed. The combined use of sodar data, as well as 915-MHz wind profiler, surface temperature, dewpoint, and wind data, provides a more-comprehensive definition of the early-evening boundary layer transition. Sodar backscatter is sensitive to temperature fluctuations, and therefore as the heat flux decreases, the sodar return power exhibits changes from a time-varying convective structure to a more-stratified and steady structure. A relative minimum in intensity and height of the sodar backscatter is one indication that the transition is occurring. As the boundary layer evolves from the unstable convective afternoon conditions to the more stable nocturnal conditions, the finescale temporal variations in many parameters, including temperature, the 10–2-m temperature difference, dewpoint, and wind speed, decrease. There is often a distinct steplike shape in the temperature/wind decrease or dewpoint increase within 30 min of the sodar minimum. In this paper, an analysis of sodar and surface data is presented for low-wind cases to demonstrate the efficacy of this combined sensor technique, and to illustrate the average physical characteristics of the transition period for 21 cases during the summer months (June–August) and 9 cases during the autumn months (November–December) in Huntsville, Alabama.

Turbulence in the nocturnal boundary layer with light and variable winds

AbstractTurbulence quantities are analyzed from nine months of data collected on the floor of a valley where nocturnal cold pools are frequent. Often the speed of the vector‐averaged wind over the night is less than 0.5 m s−1 (near‐calm winds) with no preference for wind direction. The quantity of such near‐calm data is sufficiently large to allow new types of analyses as well as the opportunity to examine statistics of the previously ignored near‐neutral subclass of near‐calm winds.For near‐calm weak winds and strong stratification, the turbulence can be difficult to isolate from wave‐like motions and more complex small‐scale structures. The smallest scale perturbations on time‐scales less than 5 s behave most like turbulence. Larger‐scale perturbations are characterized by very weak vertical velocity fluctuations and large temperature fluctuations, but lead to systematic downward heat flux after extensive averaging.For near‐calm nocturnal conditions, significant turbulence is mainly generated by short‐term (minutes) accelerations of unknown origin. The turbulence between such infrequent mixing events is extremely weak, but not zero. While the turbulence in the events approximately follows similarity theory, the extremely weak turbulence scales neither with stratification nor bulk shear, and its inferred vertical length‐scale is small compared to the distance from the ground, even at the 2 m level. Copyright © 2012 Royal Meteorological Society

Driver drowsiness detection system under infrared illumination for an intelligent vehicle

Statistics on traffic accidents reveal that human error is the main cause of deaths and injuries on roads worldwide every day. In order to reduce the amount of such fatalities, a module for an advanced driver assistance system, which caters for automatic driver drowsiness detection and also driver distraction, is presented. Artificial intelligence algorithms are used to process the visual information in order to locate, track and analyse both the driver's face and eyes to compute the drowsiness and distraction indexes. This real-time system works during nocturnal conditions as a result of a near-infrared lighting system. Finally, examples of different driver images taken in a real vehicle at nighttime are shown to validate the proposed algorithms.

Analysis of relative factors of tumble among senile cerebrovascular diseases patients

Objective To study the related factors of tumble among senile cerebrovascular diseases patients,so as to effectively prevent it happening.Methods A total of 102 senile cerebrovascular diseases patients with the history of tumble within 12 months were investigated with self-designed questionnaire.Results The incidence of tumble among male patients was 42.16％,while female patients was6.86％ ;living alone patients was 37.25％,while cohabit patients was 16.67％ ;balance ability abnormal patients was 38.24％,while that normal patients was 22.55％.There was significantly difference between them(x2 =4.95,8.45,5.13 ;P ＜0.05 or P ＜ 0.01).The tumble incidence among patients with different ages,medicine or not,nocturnal enuresis condition,eyesight,intelligence and different chronic diseases was significantly difference(P ＜0.05 or P ＜0.01).Conclusions The incidence of tumble among senile cerebrovascular diseases patients are related to many factors,so it is important to assessment their health condition and establish effective preventive measures to reduce the ratio of tumble. Key words: Cerebrovascular disease; Senile; Tumble; Relative factors

Management of hypophosphatemia in nocturnal hemodialysis with phosphate-containing enema: A technical study

Hypophosphatemia is observed in patients undergoing nocturnal hemodialysis. Phosphate is commonly added to the dialysate acid bath, but systematic evaluation of the safety and reliability of this strategy is lacking. The objectives of this study were 4-fold. First, we determined whether predictable final dialysate phosphate concentrations could be achieved by adding varying amounts of Fleet® enema. Second, we assessed the stability of calcium (Ca) and phosphate dialysate levels under simulated nocturnal hemodialysis conditions. Third, we assessed for Ca-phosphate precipitate. Finally, we evaluated whether dialysate containing Fleet® enema met the current sterility standards. We added serial aliquots of enema to 4.5 L of dialysate acid concentrate and proportioned the solution on Gambro and Althin/Baxter dialysis machines for up to 8 hours. We measured dialysate phosphate, Ca, pH, and bicarbonate concentrations at baseline, and after simulated dialysis at 4 and 8 hours. We evaluated for precipitation visually and by assessing optical density at 620 nm. We used inoculation of agar to detect bacteria and Pyrotell reaction for endotoxin. For every 30 mL of Fleet® (1.38 mmol/mL of phosphate) enema added, the dialysate phosphate concentration increased by 0.2 mmol/L. There were no significant changes in dialysate phosphate, Ca, pH, and bicarbonate concentrations over 8 hours. No precipitate was observed in the dialysate by optical density measures at 620 nm for additions of up to 90 mL of enema. Bacterial and endotoxin testing met sterility standards. The addition of Fleet® enema to dialysate increases phosphate concentration in a predictable manner, and no safety problems were observed in our in vitro studies.

Forecasting urban PM10 and PM2.5 pollution episodes in very stable nocturnal conditions and complex terrain using WRF–Chem CO tracer model

This study presents a system to predict high pollution events that develop in connection with enhanced subsidence due to coastal lows, particularly in winter over Santiago de Chile. An accurate forecast of these episodes is of interest since the local government is entitled by law to take actions in advance to prevent public exposure to PM10 concentrations in excess of 150 μg m−3 (24 h running averages). The forecasting system is based on accurately simulating carbon monoxide (CO) as a PM10/PM2.5 surrogate, since during episodes and within the city there is a high correlation (over 0.95) among these pollutants. Thus, by accurately forecasting CO, which behaves closely to a tracer on this scale, a PM estimate can be made without involving aerosol-chemistry modeling. Nevertheless, the very stable nocturnal conditions over steep topography associated with maxima in concentrations are hard to represent in models. Here we propose a forecast system based on the WRF–Chem model with optimum settings, determined through extensive testing, that best describe both meteorological and air quality available measurements. Some of the important configurations choices involve the boundary layer (PBL) scheme, model grid resolution (both vertical and horizontal), meteorological initial and boundary conditions and spatial and temporal distribution of the emissions. A forecast for the 2008 winter is performed showing that this forecasting system is able to perform similarly to the authority decision for PM10 and better than persistence when forecasting PM10 and PM2.5 high pollution episodes. Problems regarding false alarm predictions could be related to different uncertainties in the model such as day to day emission variability, inability of the model to completely resolve the complex topography and inaccuracy in meteorological initial and boundary conditions. Finally, according to our simulations, emissions from previous days dominate episode concentrations, which highlights the need for 48 h forecasts that can be achieved by the system presented here. This is in fact the largest advantage of the proposed system.

On concentration footprints for a tall tower in the presence of a nocturnal low-level jet

This paper reports on the location of sources contributing to a point concentration measurement in the stable boundary layer. Concentration footprints for sensors located at different heights during the night are examined using a backward-in-time Lagrangian stochastic dispersion model. Simulations of air parcel transport in a non-steady-state atmospheric boundary layer above a bare surface and a forest under different insolation suggest that sources located as far as several hundred kms away contribute to a concentration measurement made at levels as high as 500 m. The origin of the maximal contribution area shifts during the night depending on the wind direction at the sensor location, a feature most prominent in the presence of decoupling between sensor levels and surface sources. Simulations suggest that atmospheric static stability alone is not a sufficient criterion to trigger flow decoupling. The presence of the low-level jet provides vertical mixing of air parcels even for stable boundary layers with Richardson numbers higher than the critical. This finding is in agreement with earlier observations suggesting that the level of the low-level jet nose acts as a strong lid prohibiting vertical gas propagation. These findings have important implications in the interpretation of eddy-flux measurements in nocturnal conditions.

Vehicular Ad Hoc Networks

With vehicular ad hoc networks gaining an ever-increasing interest to serve a diverse variety of applications in today’s intelligent transportation systems, it was not at all surprising for the guest editorial team to receive a handful of submissions for this special issue addressing different aspects and test-beds of vehicular networks. In sum, 8 papers were accepted to be published in the special issue. An interesting note to make is that 5 of the accepted papers had an actual experimental implementation carried out in the road and under real-world conditions. This certainly helps to justify their application and usefulness for future deployment by the industry and authorities.While all papers address enhancing the safety and efficiency of driving, each of them addresses a certain aspect of this issue. The paper by M. J. Flores et al., “Driver Drowsiness Warning System Using Visual Information for Both Diurnal and Nocturnal Illumination Conditions,” seeks to locate, track, and analyze both the drivers face and eyes to compute a drowsiness index under varying light conditions (diurnal and nocturnal). In their paper “Multiobjective Reinforcement Learning for Traffic Signal Control Using Vehicular Ad Hoc Network,” D. Houli et al. propose a new multiobjective control algorithm based on reinforcement learning for urban traffic signal control, named, multi-RL. M. Tsukada et al. in “Design and Experimental Evaluation of a Vehicular Network Based on NEMO and MANET,” present a policy-based solution to distribute traffic among multiple paths to improve the overall performance of a vehicular network. The paper “Traffic Data Collection for Floating Car Data Enhancement in V2I Networks” by D. F. Llorca et al. presents a complete vision-based vehicle detection system for floating car data (FCD) enhancement in the context of vehicular ad hoc networks. S. Miyata et al. in “Improvement of Adaptive Cruise Control Performance” propose a more accurate method for detecting the preceding vehicle by radar while cornering. The paper “Reducing Congestion in Obstructed Highways with Traffic Data Dissemination Using Ad hoc Vehicular Networks” by T. D. Hewer et al. presents a message-dissemination procedure that uses vehicular wireless protocols to influence vehicular flow, reducing congestion in road networks. M. Koubek et al., in “Reliable Delay ConstrainedMultihop Broadcasting in VANETs,” focus onmechanisms that improve the reliability of broadcasting protocols, where the emphasis is on satisfying the delay requirements for safety applications. Finally, M. G. Cinsdikici and K. Memis in “Traffic Flow Condition Classification for Short Sections Using Single Microwave Sensor” seek to identify the current traffic condition by examining the traffic measurement parameters and taking into account occupancy as another important parameter of classification. We hope this special issue can help the research community further its understanding of this emerging field.

Hearing is not necessarily believing in nocturnal anurans

The recent discovery of the use of visual cues for mate choice by nocturnal acoustic species raises the important, and to date unaddressed, question of how these signals affect the outcome of mate choice predicted by female preference for male calls. In order to address this question, we presented female Hyla arborea tree frogs with a series of choices between combinations of acoustic and visual cues of varying quality in nocturnal conditions. While females exhibited the expected preference for a combination of attractive values for visual and acoustic signals over combinations of unattractive values for both signals, when presented with conflicting acoustic and visual cues, they equally adopted one of two strategies, preferring either attractive calls or intense vocal sac coloration. This constitutes novel evidence that the outcome of mate choice, as predicted on the basis of male calling quality, can be drastically different when additional communication modalities--in this case vision--are taken into account. These results also highlight the possible existence of individual variation in female rules for cue prioritization. The implications of these results for the study of mate choice in nocturnal acoustic species are discussed.

八丈島における｀２２２´Ｒｎ散逸率の評価とその大気中濃度への影響

222Rn fluxes from the ground surface and 226Ra contents in soil were measured on Hachijo-jima Island, which is a solitary island in the Pacific Ocean located about 200 km to the south of the main island of Japan, to evaluate fractional contributions of the locally exhaled 222Rn and the long-range transported one to the surface air concentration measured on this island. Averages of 222Rn flux and 226Ra content in dry soil were evaluated to be 0.9 ± 0.4 mBq m-2 s-1 and 6.8 ± 0.2 Bq kg-1, respectively. These are considerably smaller than the respective values of 9.7 ± 0.8 mBq m-2 s-1 and 23.2 ± 0.4 Bq kg-1 measured at Nagoya as a reference. The lower value of the 226Ra content and the even lower 222Rn flux on this island can be attributed to the basaltic geology and the soil's coarse texture and high moisture, respectively. A simple model calculation assuming a typical nocturnal condition showed that the measured 222Rn flux would cause only a small increase in the surface air concentration by 0.035 to 0.072 Bq m-3 (relative contribution of 1 to 12%) in addition to the long-range transported 222Rn under a typical nocturnal condition. The contribution of the local flux would be smaller than that under nocturnal condition. This local 222Rn component is negligible as compared with the concentration of the long-range transported 222Rn (0.6 to 3.6 Bq m-3). It is, therefore, concluded that Hachijo-jima Island is suitable for measuring the long-range transported atmospheric 222Rn in East Asia region.

Visual cues and parental favouritism in a nocturnal bird

Visual signals are crucial for parent-offspring communication, although their functioning has been neglected for nocturnal birds. Here, we investigated parental preference for nestling coloration in nocturnal conditions--a question hitherto unexplored--in a nocturnal raptor, the scops owl (Otus scops). We assessed how parents allocated food during the night in relation to a manipulation of ultraviolet (UV) reflectance of the cere (skin above the beak) of their offspring. Reflectance of the cere shows a marked peak in the UV part of the spectrum, and location of the UV peak is related to nestling body mass (i.e. heavier nestlings have a UV peak at lower wavelengths). We found evidence of parental bias in favour of lighter offspring: UV-reduced nestlings gained more weight during the night than their control siblings. This study provides the first experimental evidence of the use of visual cues for parent-offspring communication in a nocturnal bird.

Comparison of indirect methods for the estimation of Boundary Layer height over flat-terrain in a coastal site

In this paper an analysis of different indirect methods for the calculation of the boundary layer height (BLH) using sodar, ultrasonic anemometer and a prognostic model based on single point surface measurements is presented. In particular the automatic spectral routine developed for Remtech sodar is compared with the results obtained with the parameterization of the vertical velocity variance of a minisodar, with the calculation of a prognostic model, with a parameterization based on horizontal velocity spectra and with the BLH evaluated from the intensity of minisodar echoes in stable conditions. The data of a radiosonde system taken in a nearby site was also analysed to get an independent evaluation of BLH for comparison. There is a significant scatter in the data for both the evaluation through the variance of vertical wind speed and the spectral analysis of the horizontal wind velocity although created by different effects. In unstable conditions the different methods give a similar pattern even if the prognostic model in some days predicts a significantly higher BLH with respect to the other methods. In stable nocturnal conditions the performances of the Remtech routine are worse than those in unstable conditions with an evident overestimation of the BLH that it is likely related to the overestimation of vertical turbulence and to the use of multiple range gates in the algorithm. Taking as reference the evaluation of BLH of the sodar, the spectral method applied to ultrasonic anemometer data seems to be affected by the lowest biases and it is a possible candidate, for the development of automatic routines for operational evaluation of BLH possibly with a different parameterisation for stable and unstable cases.