Early Evening Hours Research Articles

Ameliorative Strategies to Sustain Livestock Production during Heat Stress

Ameliorative Strategies to Sustain Livestock Production during Heat Stress In the changing climate scenario, heat stress is of major concern among livestock owners as it affects drastically livestock production which otherwise contributes 40% of world agriculture GDP (gross domestic product). Hence there is an urgent need for reviewing the various strategies to counter the heat stress impact on livestock production. THI (temperature humidity index) may not be the ideal index to quantify heat stress impact on livestock as it does not take into account solar radiation and wind velocity. Hence, more appropriate agro-ecological zone specific indices like Dairy Heat Load Index (DHLI) which takes into account all cardinal weather parameters is the need of hour. Development of appropriate heat abatement strategies depends on the type of dairy operation practiced in a particular livestock farm. During heat stress, management strategies such as providing shade, sprinklers, fans, cold water, minimum handling, grazing during early morning and late evening hours might be very beneficial to improve livestock production..

First results on low‐latitude E and F region irregularities obtained using the Gadanki Ionospheric Radar Interferometer

AbstractA 30 MHz radar has recently been established at Gadanki (13.5°N, 79.2°E; 6.5°N magnetic latitude) to make unattended observations of the ionospheric field‐aligned irregularities (FAI). This radar, called the Gadanki Ionospheric Radar Interferometer (GIRI), has been designed to have scanning capability of 100° in the east‐west plane perpendicular to Earth's magnetic field and interferometry/imaging system to study drifts and spatial distribution of plasma irregularities at both large and small scales. In this paper, we present the first results on the E and F region FAI made using the scanning capability of the GIRI. Daytime observations of E region FAI show type 2 echoes with velocities predominantly upward northward (downward‐southward) at altitudes >100 km (<100 km) and westward (eastward) in the forenoon (afternoon) with signature of tidal wind field. F region irregularities show bottom‐type, bottomside and plume structures with close resemblance to those observed over the magnetic equator. Observations made with the east‐west scanning capability have been used to study the origin, evolution, and drift of the FAI for the first time from Gadanki. Eastward drifts are estimated to be 90–210 m s−1 during 20–24 LT. Upward velocity as large as 500 m s−1 has been observed in the initial phase of the plume structures. Intriguingly, downward velocity as large as 60 m s−1 has also been observed in the plumes, displaying descending pattern, observed in the early evening hours. These results are presented and discussed in the light of current understanding of low‐latitude plasma irregularities, and future prospects of GIRI are outlined.

Enhancement of cloud-to-ground lightning activity over Taipei, Taiwan in relation to urbanization

Collecting the cloud-to-ground (CG) lightning flash data from Tai-Power Company of Taiwan, a long term study has been performed to investigate the enhancement of lightning activity in and around Taipei City, the largest metropolitan city of Taiwan, in relation to urbanization, for the period of 2005–2010. Results reveal that negative flash density is enhanced by approximately 64% while the positive flash density is enhanced by 48%, over and downwind of the city compared with other neighboring areas. On the other hand a decrease of nearly 24% in the percentage of positive flashes occurs over and downwind of Taipei compared to upwind values. We have also investigated the effect of urbanization on peak current of both polarities but no significant effect is noticed. Possible influence of urban particulate matter on the enhancement of CG lightning activity has been analyzed utilizing the annual averages of PM10 (particulate matter with aerodynamic diameter smaller than 10μm) and SO2 (sulfur dioxide) concentrations data. Interesting results are found, indicating the higher concentrations of PM10 and SO2 contributes to the CG lightning enhancement. Both the concentrations exhibit a positive linear correlation with the percent change in CG flashes from the upwind to the urban area and from the upwind to the downwind area. However, the correlation coefficient for PM10 concentrations is comparatively much lower than SO2 concentrations. Positive correlations of 0.55 and 0.68 are found for the PM10 and SO2 concentrations, respectively, when compared separately with the percent change in CG flashes from the upwind to the downwind area, indicating the influence of aerosols on urban CG lightning enhancement. Hourly variation of lightning flashes show that the urban effects on CG lightning is prominent in the afternoon and early evening hours. The results obtained from the present analysis corroborate the results reported in the literature by other researchers.

Tornado Climatology of Turkey

Abstract A climatology of tornadoes in Turkey is presented using records from a wide variety of sources (e.g., the Turkish State Meteorological Service, European Severe Weather Database, newspaper archives, Internet searches, etc.). The climatology includes the annual, diurnal, geographical, and intensity distributions of both mesocyclonic and nonmesocyclonic tornadoes. From 1818 to 2013, 385 tornado cases were obtained. The tornadoes range from F0 to F3, with F1 being the most frequently reported or inferred intensity. Mesocyclonic tornadoes are most likely in May and June, and a secondary maximum in frequency is present in October and November. Nonmesocyclonic tornadoes (waterspouts) are most common in the winter along the (southern) Mediterranean coast and in the fall along the Black Sea (northern) coast. Tornadoes (both mesocyclonic and nonmesocyclonic) are most likely in the afternoon and early evening hours.

Observation of ionospheric irregularities around midnight and post-midnight near the northern crest of the Equatorial Ionization Anomaly in the Indian longitude sector: Case studies

Multistation and multi-technique observation of equatorial ionospheric irregularities from locations over the magnetic equator through the northern crest of the Equatorial Ionization Anomaly (EIA) and beyond is one of the important objectives of the Indian CAWSES program. For this purpose, multistation observational campaign was conducted during September 2011, April 2012 and September 2012 involving GPS TEC and S4 from Calcutta situated virtually underneath the northern crest of the EIA, and GPS S4 measurements from Siliguri, located beyond the northern crest of the EIA. Intense amplitude scintillation observations have been noted around midnight and post-midnight hours on certain GPS links located north of Siliguri with no scintillation patches during pre-midnight period. Satellite links experiencing scintillations from Siliguri were unaffected at Calcutta. Day-to-day variability has been noted in the maximum northern observation of GPS scintillations at different S4 levels from both Calcutta and Siliguri. Simultaneous observations from Siliguri and Calcutta indicate that post-midnight GPS amplitude scintillations are possibly associated with interaction of traveling ionospheric disturbances from mid-latitudes towards the equator, with transionospheric GPS links contrary to early evening hours when such movement are usually from over the magnetic equator towards the northern and southern crests of EIA. The present paper reports three cases of ionospheric irregularity tracking using the above stations on September 25, 2012, April 12, 2012 and September 11, 2011, all magnetically quiet days. Information related to the variabilities of latitudinal extent of scintillation observations along 88°E meridian at different times during 13–19UT and different levels of intensities of scintillation could provide useful information for transionospheric satellite link design and Satellite-based Augmentation System (SBAS).

Numerical simulation of "an American haboob"

Abstract. A dust storm of fearful proportions hit Phoenix in the early evening hours of 5 July 2011. This storm, an American haboob, was predicted hours in advance because numerical, land–atmosphere modeling, computing power and remote sensing of dust events have improved greatly over the past decade. High-resolution numerical models are required for accurate simulation of the small scales of the haboob process, with high velocity surface winds produced by strong convection and severe downbursts. Dust productive areas in this region consist mainly of agricultural fields, with soil surfaces disturbed by plowing and tracks of land in the high Sonoran Desert laid barren by ongoing draught. Model simulation of the 5 July 2011 dust storm uses the coupled atmospheric-dust model NMME–DREAM (Non-hydrostatic Mesoscale Model on E grid, Janjic et al., 2001; Dust REgional Atmospheric Model, Nickovic et al., 2001; Pérez et al., 2006) with 4 km horizontal resolution. A mask of the potentially dust productive regions is obtained from the land cover and the normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The scope of this paper is validation of the dust model performance, and not use of the model as a tool to investigate mechanisms related to the storm. Results demonstrate the potential technical capacity and availability of the relevant data to build an operational system for dust storm forecasting as a part of a warning system. Model results are compared with radar and other satellite-based images and surface meteorological and PM10 observations. The atmospheric model successfully hindcasted the position of the front in space and time, with about 1 h late arrival in Phoenix. The dust model predicted the rapid uptake of dust and high values of dust concentration in the ensuing storm. South of Phoenix, over the closest source regions (~25 km), the model PM10 surface dust concentration reached ~2500 μg m−3, but underestimated the values measured by the PM10 stations within the city. Model results are also validated by the MODIS aerosol optical depth (AOD), employing deep blue (DB) algorithms for aerosol loadings. Model validation included Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), equipped with the lidar instrument, to disclose the vertical structure of dust aerosols as well as aerosol subtypes. Promising results encourage further research and application of high-resolution modeling and satellite-based remote sensing to warn of approaching severe dust events and reduce risks for safety and health.

Effects of Residential Wood-Burning Emissions during Winter Months in a Northern San Diego County Location

Ambient particulate matter (PM10 and PM2.5) and carbon monoxide (CO) due to domestic wood burning during the winter and summer months in the city of Escondido were investigated. The data collected from January 2000 to December 2010 from San Diego Air Pollution Control District's (SDAPCD's) collection station in Escondido were analyzed by both non-paired student's t-tests and Mann-Whitney U tests (significance of 0.05 for both tests). For all three pollutants, the significant differences in levels between the winter and summer months, the significant differences in levels during the days that were celebrated as holidays and normal days, and the significant differences in levels between weekends and weekdays were noted. Additionally, the significant differences in levels between night and daytime, early evening hours and night and during burning and smoldering fires were determined for hourly PM2.5 and CO data. For all emission types, traffic patterns did not match the levels of emissions on weekdays, weekends, evenings, or daytimes. Elemental and organic carbon species taken from PM2.5 data correlated with the original PM2.5 filter data. Results of our analysis suggest that wood burning is a source of PM10, PM2.5, and CO in the area.

Daily and annual patterns of thermoregulation in painted turtles (Chrysemys picta marginata) living in a thermally variable marsh in Northern Michigan

The capacity for an ectothermic reptile to thermoregulate has implications for many components of its life history. Over two years, we studied thermoregulation in a population of Midland painted turtles (Chrysemys picta marginata) in a shallow, thermally variable wetland during summer in Northern Michigan. Mean body temperature (Tb) of free-ranging turtles was greater in 2008 (25.8°C) than in 2010 (19.7°C). Laboratory determined thermoregulatory set point (Tset) ranged from 25°C (Tset-min) to 31°C (Tset-max) and was lower during the fall (17–26°C). Deviations of Tb distributions from field measured operative temperatures (Te) and indices of thermoregulation indicated that C. picta marginata were capable of a limited degree of thermoregulation. Operative temperatures and thermal quality (de=|Tset-min−Te| and |Te−Tset-max|) cycled daily with maximal thermal quality occurring during late morning and late afternoon. The accuracy of thermoregulation (db=|Tset-min−Tb| and |Tb−Tset-max|) was maximal (db values were minimal) as Tb declined and traversed Tset during the late afternoon–early evening hours and was higher on cloudy days than on sunny days because relatively low Te values decreased the number of Tb values that were above Tset. Our index of thermal exploitation (Ex=frequency of Tb observations within Tset) was 36%, slightly lower than that reported for an Ontario population of C. picta marginata. Regression of db (thermal accuracy) on de (thermal quality) indicated that turtles invested more in thermoregulation when thermal quality was low and when water levels were high than when they were low. There were no intersexual differences in mean Tb throughout the year but females had relatively high laboratory determined Tb values in the fall, perhaps reflecting the importance of maintaining ovarian development prior to winter.

Examining duration of binge eating episodes in binge eating disorder

The primary goal of this article is to examine and clarify characteristics of binge eating in individuals with binge eating disorder (BED), particularly the duration of binge eating episodes, as well as potential differences between individuals with shorter compared to longer binge eating episodes. Two studies exploring binge eating characteristics in BED were conducted. Study 1 examined differences in clinical variables among individuals (N = 139) with BED who reported a short (<2 h) versus long (≥ 2 h) average binge duration. Study 2 utilized an ecological momentary assessment design to examine the duration and temporal pattern of binge eating episodes in the natural environment in a separate sample of nine women with BED. Participants in Study 1 who were classified as having long duration binge eating episodes displayed greater symptoms of depression and lower self-esteem, but did not differ on other measures of eating disorder symptoms, compared to those with short duration binge eating episodes. In Study 2, the average binge episode duration was approximately 42 min, and binge eating episodes were most common during the early afternoon and evening hours, as well as more common on weekdays versus weekends. Past research on binge episode characteristics, particularly duration, has been limited to studies of binge eating episodes in bulimia nervosa. This study contributes to the existing literature on characteristics of binge eating in BED.

Glucose-Reducing Effect of the ORMD-0801 Oral Insulin Preparation in Patients with Uncontrolled Type 1 Diabetes: A Pilot Study

The unpredictable behavior of uncontrolled type 1 diabetes often involves frequent swings in blood glucose levels that impact maintenance of a daily routine. An intensified insulin regimen is often unsuccessful, while other therapeutic options, such as amylin analog injections, use of continuous glucose sensors, and islet or pancreas transplantation are of limited clinical use. In efforts to provide patients with a more compliable treatment method, Oramed Pharmaceuticals tested the capacity of its oral insulin capsule (ORMD-0801, 8 mg insulin) in addressing this resistant clinical state. Eight Type I diabetes patients with uncontrolled diabetes (HbA1c: 7.5–10%) were monitored throughout the 15-day study period by means of a blind continuous glucose monitoring device. Baseline patient blood glucose behavior was monitored and recorded over a five-day pretreatment screening period. During the ensuing ten-day treatment phase, patients were asked to conduct themselves as usual and to self-administer an oral insulin capsule three times daily, just prior to meal intake. CGM data sufficient for pharmacodynamics analyses were obtained from 6 of the 8 subjects. Treatment with ORMD-0801 was associated with a significant 24.4% reduction in the frequencies of glucose readings >200 mg/dL (60.1±7.9% pretreatment vs. 45.4±4.9% during ORMD-0801 treatment; p = 0.023) and a significant mean 16.6% decrease in glucose area under the curve (AUC) (66055±5547 mg/dL/24 hours vs. 55060±3068 mg/dL/24 hours, p = 0.023), with a greater decrease during the early evening hours. In conclusion, ORMD-0801 oral insulin capsules in conjunction with subcutaneous insulin injections, well tolerated and effectively reduced glycemia throughout the day.Trial RegistrationClinicaltrials.gov NCT00867594.

Diurnal patterns in lightning activity in northern tropical Africa

The study analyzes summertime lightning incidence data across northern tropical Africa from the TRMM satellite sensor during 1998–2011. It uses harmonic analyses to detect the spatial patterns in diurnal variations of lightning activity across the study area. The results are in conformity with previous studies examining diurnal patterns of convective weather processes in this region, with most lightning activity concentrated over land areas. The peak time of lightning activity over most of the study area was during late afternoon hours, from around 1700 to 1900 local standard time. The peak time of lightning activity was observed during early morning hours in some coastal areas, such as Cameroon, which can be a result of local-level convergence between the land and sea breeze. A general progression in the time of lightning activity from late afternoon to early evening hours was observed throughout the interior of the study area, which may be attributed to land-surface heating and associated mesoscale convective systems, and to upper-level circulation in the form of the African Easterly Jet Stream.

Diurnal variations in summertime lightning activity in Tropical Asia

ABSTRACTMany meteorological phenomena exhibit distinctive diurnal variations that vary substantially from place to place. In this investigation, we use Tropical Rainfall Measuring Mission data to assess spatial patterns in the diurnal variations of summertime lightning activity throughout tropical Asia. Harmonic analysis of the dataset reveals strong diurnal patterns in lightning activity with most locations exhibiting an afternoon maximum and a late‐night, early morning minimum. Notable exceptions include the eastern coastal areas of the Indian subcontinent and China, with the peak activity occurring in the early evening hours. We generally find that the diurnal patterns are related to orographic interactions as well as the seasonal wind circulation of onshore winds along the coastal areas. The strength of the cycle was relatively stronger in the interior of the continent particularly over northwestern India and the Tibetan plateau. Copyright © 2013 Royal Meteorological Society

Malaria transmission intensity and dynamics of clinical malaria incidence in a mountainous forest region of Ghana.

Malaria transmission is heterogeneous. Villages close to each other may have very different transmission characteristics. The presence and abundance of malaria vectors is governed by local ecology and microclimate. Knowledge of the dynamics of transmission is important for planning and evaluation of malaria control strategies. This study investigated the heterogeneity of malaria transmission in preparation for a vaccine trial and offers insights into dynamics of malaria incidence in the forest zone of Ghana. Malaria transmission was assessed in four villages with different micro-ecological features in the forest zone of the Akwapim-Mampong Range in Ghana, water shed with rivers flowing north to Lake Volta in the south. Human landing catches (HLC) of mosquitoes were conducted and Plasmodium falciparum circumsporozoite rates were assessed by ELISA. Sporozoite prevalence, annual biting rates (ABR) and entomological inoculation rates (EIR) from the four study sites were compared with climatological and ecological data. Regression analysis was used to compare transmission data and blood parasite prevalence, parasite density (PD) and malaria episodes from children in the study area. Additionally we examined trends in confirmed clinical malaria incidence from 2005 -2012. In total 1307 Anopheles gambiae s.l. and 54 An. funestus females were caught by HLC from November 2003 to August 2005. Sporozoites in Anopheles vectors in four villages ranged from 4.0 to 10.2%, ABR from 371 to 1890 and EIR from 40 to 158. Linear regression on parasitological and clinical data of children from the villages revealed that the ABR significantly influenced the parasite density (PD) of P. falciparum. Malaria transmission was intense and heterogeneous and corresponded to the micro-ecological differences. Malaria transmission in the early evening hours before people went to sleep was enough to sustain stable malaria. Scaling up preventive measures to reduce exposure to vectors will be effective in reducing parasitemia in children. Variations in transmission intensity must be considered when evaluating impact of control strategies and interventions such as the vaccine trials.

Black carbon aerosol variations over Patiala city, Punjab, India—A study during agriculture crop residue burning period using ground measurements and satellite data

In the present study, we have analyzed the variations in black carbon (BC) aerosol mass concentration over Patiala city, Punjab, India, during October/November-2008 associated with agriculture crop residue burning activities. BC mass concentration, observed to be very high (above 20μgm−3) on certain days during November-2008, was closely associated with intensive agriculture crop residue burning practices over the region. Higher values (>1.0) of ground-measured aerosol optical depth (AOD) together with increase (>1.2) in angstrom exponent (α) values suggested dominance of fine mode aerosols over the region. Satellite observations clearly define the fire spot areas and the enhanced aerosol burden over the region. BC absorption coefficient calculated from seven channels aethalometer exhibits a pronounced diurnal variation with higher values during early morning and evening hours and lower during noon and early afternoon associated with biomass-burning activities and boundary-layer dynamics over the region.

Equatorial plasma bubble zonal velocity using 630.0 nm airglow observations and plasma drift modeling over Ascension Island

We present OI (630.0 nm) airglow image data from Ascension Island (geographic: 7.9°S, 14.4°W; dip latitude: 16°S) in the southern Atlantic Ocean taken with the Utah State University all‐sky CCD camera during 20 March to 7 April 1997 in order to study plasma bubbles occurring in the low‐latitude nighttime ionosphere. The initial plasma bubble onset occurs in the early evening hours at ∼19:15–20:00 LST and is followed by eastward propagation with an average speed of ∼90–120 m/s prior to local midnight, rapidly decreasing around the midnight and postmidnight periods. The Ascension results are compared with similar observations from Christmas Island in order to examine the longitudinal variations of EPB development and propagation. The observed EPB velocities from Ascension Island are also compared with the results of a plasma drift model. In a case study during the night of 4–5 April, the velocity reveals unusual latitudinal shear, up to 0.12 m/s/km, with a reversal to westward flow at low latitudes while eastward flow is maintained at higher latitudes. Consequently, the bubble rotates counterclockwise and tilts eastward, significantly away from alignment with the geomagnetic field lines. The westward reversal of the drift motion near the geomagnetic equator is most likely the result of a reversal in the F region dynamo or from a large increase in the altitude of the shear node in the F region plasma drift at the geomagnetic equator.

Comparison of nighttime zonal neutral winds and equatorial plasma bubble drift velocities over Brazil

We present results from the first extended period of coincident observations of thermospheric zonal neutral winds and equatorial plasma bubble (EPB) zonal drift velocities over northeastern Brazil during the October to December months of 2009 and 2010. The EPB zonal drift velocities are estimated utilizing images of the O I 630.0 nm emissions recorded by a wide‐angle imaging system at Cajazeiras. Thermospheric neutral wind estimates are based upon common volume observations made by a bistatic Fabry‐Perot interferometer (FPI) experiment using FPIs located at Cajazeiras and Cariri in Brazil observing the Doppler shift of the O I 630.0 nm emission. The results illustrate a similar pattern of nighttime and night‐to‐night variations in the zonal neutral winds and EPB zonal drift velocities. In general, the geomagnetic zonal neutral winds and the EPB velocities show an excellent agreement illustrating that the F region dynamo is fully developed. However, in the early evening hours the EPB zonal speed is slower than that of the background winds on several occasions. We conclude that this indicates that during the bubble evolution period in the early evening the F region dynamo is not fully activated.

Diurnal pattern of seizures outside the hospital

To evaluate whether the distribution of seizures throughout the day is the same in ambulatory outpatient conditions as observed in inpatient conditions. We analyzed records from consecutive patients who had ambulatory EEG monitoring for 24 to 72 hours using Digitrace™ EEG recording system. The participants maintained a log of symptoms and signaled the time when symptoms occurred by pushing an event button. Additionally, automatic seizure and spike detection was performed on each record using Persyst detection software. Of 831 reports analyzed, 44 unique patients had definite ictal events. There were a total of 129 electrographic seizures (34 subclinical) with timing as follows: frontal (31), temporal (71), and generalized, posterior, or central (27). Frontal lobe seizures occurred more frequently between 12 am and 12 pm as compared to temporal lobe seizures, which occurred more frequently between 12 pm and 12 am (p = 0.017). Analysis of frontal lobe seizures revealed a cluster of 10 seizures centered at 6:33 am (range 5:15-7:30 am) with p = 0.0064. Temporal lobe seizures had a cluster of 24 seizures centered at 8:49 pm (range 6:45-11:56 pm) with p = 0.0437. In ambulatory outpatient conditions, electrographic seizures follow day/night patterns similar to those observed in hospital conditions. Frontal seizures occur preferentially in the early morning hours and temporal lobe seizures occur in the early evening hours.

Observations of Thin Layers in Coastal Hawaiian Waters

Thin layers of plankton have been documented in a wide variety of environments. The growing body of observations indicates that these features are a critical component of marine ecosystem dynamics and functioning. In the past two decades, much of the research on thin layers was undertaken in temperate coastal waters. Here, we report the first known observations of thin layers of phytoplankton in tropical Hawaiian waters. We conducted an overnight shipboard study during which time we made high-resolution observations of physical and optical structure in the water column. During the overnight cruise, we observed the greatest number of thin layers in the early evening hours when thermal stratification was strongest and most persistent due to a combination of warm air and surface water, as well as light winds. A comparison of these observations with those from temperate regions leads us to hypothesize that the nature and persistence of the physical structure is very important in determining the persistence of thin layered structures. Because plankton biomass is generally lower in tropical regions, the heterogeneous aggregation of food in thin subsurface layers may be more critical to the marine ecosystem than it is in temperate regions where plankton are generally more abundant.

Particulate matter emission rates from beef cattle feedlots in Kansas—Reverse dispersion modeling

Open beef cattle feedlots emit various air pollutants, including particulate matter (PM) with equivalent aerodynamic diameter of 10 μm or less (PM10); however, limited research has quantified PM10 emission rates from feedlots. This research was conducted to determine emission rates of PM10 from large cattle feedlots in Kansas. Concentrations of PM10 at the downwind and upwind edges of two large cattle feedlots (KS1 and KS2) in Kansas were measured with tapered element oscillating microbalance (TEOM) PM10 monitors from January 2007 to December 2008. Weather conditions at the feedlots were also monitored. From measured PM10 concentrations and weather conditions, PM10 emission rates were determined using reverse modeling with the American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model (AERMOD). The two feedlots differed significantly in median PM10 emission flux (1.60 g/m2-day for KS1 vs. 1.10 g/m2-day for KS2) but not in PM10 emission factor (27 kg/1000 head-day for KS1 and 30 kg/1000 head-day KS2). These emission factors were smaller than published U.S. Environmental Protection Agency (EPA) emission factor for cattle feedlots. Implications This work determined PM10 emission rates from two large commercial cattle feedlots in Kansas based on extended measurement period for PM10 concentrations and weather conditions, and reverse dispersion modeling, providing baseline information on emission rates for cattle feedlots in the Great Plains that could be used for improving emissions estimates. Within the day, PM emission rates were generally highest during the afternoon period; PM emission rates also increased during early evening hours. In addition, PM emission rates were highest during warm season and prolonged dry periods. Particulate control measures should target those periods with high emission rates.

Effects of prior light exposure on early evening performance, subjective sleepiness, and hormonal secretion.

In sighted humans, light intensity, timing, exposure duration, and spectral composition of light are important to entrain the endogenous circadian pacemaker to the 24-h day-night cycle. We tested the impact of two realistic office lighting conditions during the afternoon on subjective sleepiness, hormonal secretion, and cognitive performance in the early evening hours. Twenty-nine young subjects came twice and spent 8 h (12:00-20:00) in our laboratory, where they were exposed for 6 h to either artificial light (AL) or to mainly daylight (DL). In the early evening, we assessed their salivary cortisol and melatonin secretion, subjective sleepiness, and cognitive performance (n-back test) under dim light conditions. Subjects felt significantly more alert at the beginning of the evening after the DL condition, and they became sleepier at the end of the evening after the AL condition. For cognitive performance we found a significant interaction between light conditions, mental load (2- or 3-back task) and the order of light administration. On their first evening, subjects performed with similar accuracy after both light conditions, but on their second evening, subjects performed significantly more accurately after the DL in both n-back versions and committed fewer false alarms in the 2-back task compared to the AL group. Lower sleepiness in the evening was significantly correlated with better cognitive performance (p < .05). In summary, even short-term lighting conditions during the afternoon had an impact on cognitive task performance in the evening. This rapid effect was only distinguishable on the second day of training, when a difficult task had been sufficiently practiced.