Search

The interaction between corn particle size and feed additives as it pertains to broiler live performance has been overlooked. This study evaluated the effects of corn particle size and refined-functional carbohydrates (RFC; 100 g/MT) on live performance and Salmonella prevalence in coccidiosis-vaccinated broilers. The following treatments were applied: fine corn (FC), coarse corn (CC), FC+RFC, CC+RFC, and CC+SAL (salinomycin). A natural, non-experimental necrotic enteritis (NE) outbreak began at 12 D of age, and mortality was impacted by dietary treatments. The use of RFC was observed to increase NE-associated mortality compared to broilers fed CC+SAL (P ≤ 0.10). At 19 D, greater than 50% of all broilers were found to be Salmonella-positive; however, at 48 D the use of RFC was shown to decrease cecal Salmonella prevalence. Although differences in early mortality were observed, coccidiosis-vaccinated broilers fed CC or CC+RFC exhibited similar BW and FCR as broilers fed CC+SAL at 48 D (P ≤ 0.05). These data suggested that CC use after 10 D may provide value in a production system free of antibiotic growth promoters and coccidiostats by ameliorating live performance losses associated with coccidiosis vaccination. Further research is warranted to determine how RFC and CC specifically affect Eimeria cycling and the immune response following coccidiosis vaccination and an NE challenge.

We examine satellite-based measurements of solar-induced chlorophyll fluorescence (SIF) over the region impacted by the Russian drought and heat wave of 2010. Like the popular Normalized Difference Vegetation Index (NDVI) that has been used for decades to measure photosynthetic capacity, SIF measurements are sensitive to the fraction of absorbed photosynthetically-active radiation (fPAR). However, in addition, SIF is sensitive to PAR as well as the fluorescence yield that is related to the photosynthetic yield. Both SIF and NDVI from satellite data show drought-related declines early in the growing season in 2010 as compared to other years between 2007 and 2013 for areas dominated by crops and grasslands. This suggests an early manifestation of the dry conditions on fPAR. Using MODIS fPAR retrievals, we computed SIF/APAR which is related to light use efficiencies (LUEs) for fluorescence and photosynthesis. We found drought-related losses in fluorescence efficiency for all areas including those dominated by mixed forests. Unlike croplands and grasslands, areas of mixed forest did not show significant drought-related declines in fPAR. We also simulated SIF and Gross Primary Productivity (GPP) using a global land surface model driven by observation-based meteorological fields. The model provides a reasonable simulation of the drought and heat impacts on SIF in terms of the spatial extents of anomalies, but some differences were found in timing of the peak drought response between modeled and observed SIF. Model data also suggested that drought-related declines in LUE for fluorescence and photosynthesis in areas of mixed forest produce losses in SIF and GPP. SIF and GPP losses due to drought in croplands and grasslands result from both LUE and fPAR reductions. The combination of SIF and NDVI or fPAR data is shown to be an important source of information for evaluating model performance.

The time scales that characterize the variations of vegetation phenology are generally much longer than those that characterize atmospheric processes. The explicit modeling of phenological processes in an atmospheric forecast system thus has the potential to provide skill to subseasonal or seasonal forecasts. We examine this possibility here using a forecast system fitted with a dynamic vegetation phenology model. We perform three experiments, each consisting of 128 independent warm-season monthly forecasts: 1) an experiment in which both soil moisture states and carbon states (e.g., those determining leaf area index) are initialized realistically, 2) an experiment in which the carbon states are prescribed to climatology throughout the forecasts, and 3) an experiment in which both the carbon and soil moisture states are prescribed to climatology throughout the forecasts. Evaluating the monthly forecasts of air temperature in each ensemble against observations—as well as quantifying the inherent predictability of temperature within each ensemble—shows that dynamic phenology can indeed contribute positively to subseasonal forecasts, though only to a small extent, with an impact dwarfed by that of soil moisture.

A common deficiency of many cloud-physics parameterizations including the NASA's microphysics of clouds with aerosol-cloud interactions (hereafter called McRAS-AC) is that they simulate lesser (larger) than the observed ice cloud particle number (size). A single column model (SCM) of McRAS-AC physics of the GEOS4 Global Circulation Model (GCM) together with an adiabatic parcel model (APM) for ice-cloud nucleation (IN) of aerosols were used to systematically examine the influence of introducing ammonium sulfate (NH4)2SO4 aerosols in McRAS-AC and its influence on the optical properties of both liquid and ice clouds. First an (NH4)2SO4 parameterization was included in the APM to assess its effect on clouds vis-à-vis that of the other aerosols. Subsequently, several evaluation tests were conducted over the ARM Southern Great Plain (SGP) and thirteen other locations (sorted into pristine and polluted conditions) distributed over marine and continental sites with the SCM. The statistics of the simulated cloud climatology were evaluated against the available ground and satellite data. The results showed that inclusion of (NH4)2SO4 into McRAS-AC of the SCM made a remarkable improvement in the simulated effective radius of ice cloud particulates. However, the corresponding ice-cloud optical thickness increased even more than the observed. This can be caused by lack of horizontal cloud advection not performed in the SCM. Adjusting the other tunable parameters such as precipitation efficiency can mitigate this deficiency. Inclusion of ice cloud particle splintering invoked empirically further reduced simulation biases. Overall, these changes make a substantial improvement in simulated cloud optical properties and cloud distribution particularly over the Intertropical Convergence Zone (ITCZ) in the GCM.

The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence of an "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summer, as a result of large-scale atmospheric feedback triggered by absorbing dust aerosols, rainfall and cloudiness are enhanced over the West Africa/Eastern Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while longwave has the opposite response. The elevated dust layer warms the air over West Africa and the eastern Atlantic. As the warm air rises, it spawns a large-scale onshore flow carrying the moist air from the eastern Atlantic and the Gulf of Guinea. The onshore flow in turn enhances the deep convection over West Africa land, and the eastern Atlantic. The condensation heating associated with the ensuing deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in a northward shift of the West Africa precipitation over land, increased low-level westerly flow over West Africa at the southern edge of the dust layer, and a near surface westerly jet underneath the dust layer over the Sahara. The dust radiative forcing also leads to significant changes in surface energy fluxes, resulting in cooling of the West African land and the eastern Atlantic, and warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at 0.95 or higher.

The direct effects of aerosols on global and regional climate during boreal spring are investigated based on numerical simulations with the NASA Global Modeling and Assimilation Office finite-volume general circulation model (fvGCM) with Microphyics of Clouds with the Relaxed–Arakawa Schubert Scheme (McRAS), using aerosol forcing functions derived from the Goddard Ozone Chemistry Aerosol Radiation and Transport model (GOCART). The authors find that anomalous atmospheric heat sources induced by absorbing aerosols (dust and black carbon) excite a planetary-scale teleconnection pattern in sea level pressure, temperature, and geopotential height spanning North Africa through Eurasia to the North Pacific. Surface cooling due to direct effects of aerosols is found in the vicinity and downstream of the aerosol source regions, that is, South Asia, East Asia, and northern and western Africa. Significant atmospheric heating is found in regions with large loading of dust (over northern Africa and the Middle East) and black carbon (over Southeast Asia). Paradoxically, the most pronounced feature in aerosol-induced surface temperature is an east–west dipole anomaly with strong cooling over the Caspian Sea and warming over central and northeastern Asia, where aerosol concentrations are low. Analyses of circulation anomalies show that the dipole anomaly is a part of an atmospheric teleconnection pattern driven by atmospheric heating anomalies induced by absorbing aerosols in the source regions, but the influence was conveyed globally through barotropic energy dispersion and sustained by feedback processes associated with the regional circulations. The surface temperature signature associated with the aerosol-induced teleconnection bears striking resemblance to the spatial pattern of observed long-term trend in surface temperature over Eurasia. Additionally, the boreal spring wave train pattern is similar to that reported by Fukutomi et al. associated with the boreal summer precipitation seesaw between eastern and western Siberia. The results of this study raise the possibility that global aerosol forcing during boreal spring may play an important role in spawning atmospheric teleconnections that affect regional and global climates.

The sensitivity of tropical atmospheric hydrologic processes to cloud microphysics is investigated using the NASA Goddard Earth Observing System (GEOS) general circulation model (GCM). Results show that a faster autoconversion rate leads to (a) enhanced deep convection in the climatological convective zones anchored to tropical land regions; (b) more warm rain, but less cloud over oceanic regions; and (c) an increased convective-to-stratiform rain ratio over the entire Tropics. Fewer clouds enhance longwave cooling and reduce shortwave heating in the upper troposphere, while more warm rain produces more condensation heating in the lower troposphere. This vertical differential heating destabilizes the tropical atmosphere, producing a positive feedback resulting in more rain and an enhanced atmospheric water cycle over the Tropics. The feedback is maintained via secondary circulations between convective tower and anvil regions (cold rain), and adjacent middle-to-low cloud (warm rain) regions. The lower cell is capped by horizontal divergence and maximum cloud detrainment near the freezing–melting (0°C) level, with rising motion (relative to the vertical mean) in the warm rain region connected to sinking motion in the cold rain region. The upper cell is found above the 0°C level, with induced subsidence in the warm rain and dry regions, coupled to forced ascent in the deep convection region. It is that warm rain plays an important role in regulating the time scales of convective cycles, and in altering the tropical large-scale circulation through radiative–dynamic interactions. Reduced cloud–radiation feedback due to a faster autoconversion rate results in intermittent but more energetic eastward propagating Madden–Julian oscillations (MJOs). Conversely, a slower autoconversion rate, with increased cloud radiation produces MJOs with more realistic westward-propagating transients embedded in eastward-propagating supercloud clusters. The implications of the present results on climate change and water cycle dynamics research are discussed.

Four different Atmospheric Radiation Measurement Program Cloud and Radiation Test Bed (ARM–CART) Single-Column Model (SCM) datasets were used to force an SCM in a number of simulations performed to study the influence of land surface fluxes on precipitation. The SCM employed Goddard Earth Observing System (GEOS-2) GCM physics, which includes a recent version of prognostic cloud scheme (Microphysics of Clouds with Relaxed Arakawa–Schubert), and a land model (Simplified Simple Biosphere Model) coupled to a highly resolved soil hydrological description in the vertical. The four ARM–CART datasets employed in these studies are referred as case 1, case 3, case 4, and case 8. The SCM simulation results broadly confirm the previous findings that an increase in the solar absorption and surface evaporation helps to increase the local rainfall, but they also reveal that the magnitude of the rainfall increase is strongly affected by the ability of the background circulation to promote moist convection. The s...

Walker-Smith, G.K. and Poore, G.C.B., 2001. A phylogeny of the Leptostraca (Crustacea) with keys to families and genera. Memoirs of Museum Victoria 58(2): 383–410. A phylogenetic analysis of the Leptostraca Claus, 1880 is undertaken using 32 of the 41 known species (including 4 undescribed species). The value of outgroups for deriving a plausible phylogeny in a group whose affinities remain contentious is discussed. A hypothetical ancestor is considered the best solution to the problem and states were scored based on general principles of crustacean evolution as evidenced by a wide variety of taxa. States of the 43 characters used in the analysis are detailed. The new phylogenetic hypothesis is compared with those of Olesen (1999). We conclude that a phylogeny based on species-level taxa and many informative characters is more likely to represent true evolutionary relationships than one based solely on genera and few characters. A new classification based on the phylogeny is derived with a new family, Paranebaliidae, being erected for Paranebalia Claus, 1880 and Levinebalia Walker-Smith, 2000. Nebaliopsididae Hessler, 1984 is supported for Nebaliopsis Sars, 1887. A restricted Nebaliidae Samouelle, 1819 for the remaining genera (Speonebalia Bowman, Yager and Iliffe, 1985, Nebaliella Thiele, 1904, Dahlella Hessler, 1984 and Nebalia Leach, 1814). Sarsinebalia Dahl, 1985 is synonomised with Nebalia. New keys and family and generic diagnoses are presented. All known species are listed with notes on distribution.

A prognostic cloud scheme named the Microphysics of Clouds with the Relaxed Arakawa–Schubert Scheme (McRAS) and the Simple Biosphere Model have been implemented in a version of the Goddard Earth Observing System (GEOS) II GCM at a 4° latitude × 5° longitude × 20 sigma-layer resolution. The McRAS GCM was integrated for 50 months. The integration was initialized with the European Centre for Medium-Range Weather Forecasts analysis of observations for 1 January 1987 and was forced with the observed sea surface temperatures and sea-ice distribution; on land, the permanent ice and vegetation properties (biomes and soils) were climatological, while the soil moisture and snow cover were prognostic. The simulation shows that the McRAS GCM yields realistic structures of in-cloud water and ice, and cloud-radiative forcing (CRF) even though the cloudiness has some discernible systematic errors. The simulated intertropical convergence zone (ITCZ) has a realistic time mean structure and seasonal cycle. The sim...

A prognostic cloud scheme named McRAS (Microphysics of Clouds with Relaxed Arakawa–Schubert Scheme) has been designed and developed with the aim of improving moist processes, microphysics of clouds, and cloud–radiation interactions in GCMs. McRAS distinguishes three types of clouds: convective, stratiform, and boundary layer. The convective clouds transform and merge into stratiform clouds on an hourly timescale, while the boundary layer clouds merge into the stratiform clouds instantly. The cloud condensate converts into precipitation following the autoconversion equations of Sundqvist that contain a parametric adaptation for the Bergeron–Findeisen process of ice crystal growth and collection of cloud condensate by precipitation. All clouds convect, advect, as well as diffuse both horizontally and vertically with a fully interactive cloud microphysics throughout the life cycle of the cloud, while the optical properties of clouds are derived from the statistical distribution of hydrometeors and i...

Scientific basis for the emergence of deep convection in the tropics at or above 28°C sea-surface temperature (SST), and its proximity to the highest observed SST of about 30°C, is explained from first principles of moist convection and TOGA-COARE data. Our calculations show that SST of 28-29°C is needed for charging the cloud-base airmass with the required moist static energy for clouds to reach the upper troposphere (i.e., 200 hPa). Besides reducing solar irradiation by cloud-cover, moist convection also produces cool and dry downdrafts, which promote oceanic cooling by increased sensible and latent heat fluxes at the surface. Consequently, the tropical ocean seesaws between the states of net energy absorber before, and net energy supplier after, the deep moist convection, which causes the SST to vacillate between 28° and 30°C. While dynamics of the large-scale circulation embodying the easterly waves and Madden-Julian Oscillations (MJOs) modulate moist convection, we show that the quasi-stationary vertical profile of moist static energy of the tropics is the ultimate cause of the upper limit on tropical SSTs.

Two 3-year (1979–1982) integrations were carried out with a version of the GLA GCM that contains the Simple Biosphere Model (SiB) for simulating land-atmosphere interactions. The control case used the usual SiB vegetation cover (comprising 12 vegetation types), while its twin, the deforestation case, imposed a scenario in which all tropical rainforests were entirely replaced by grassland. Except for this difference, all other initial and prescribed boundary conditions were kept identical in both integrations. An intercomparison of the integrations shows that tropical deforestation • decreases evapotranspiration and increases land surface outgoing longwave radiation and sensible heat flux, thereby warming and drying the planetary boundary layer. This happens despite the reduced absorption of solar radiation due to higher surface albedo of the deforested land. • produces significant and robust local as well as global climate changes. The local effect includes significant changes (mostly reductions)...

Two sets of 5-year long integrations were performed with the GLA GCM with a simple biosphere model (SiB) to delineate the influence of Amazonian deforestation on the local as well as basin wide circulation and rainfall. The control case invoked a normally forested Amazonia, while the deforestation case distinguished the partially deforested Amazonia (until the year 1988) as savanna. Except for this one difference, all other initial and the prescribed boundary conditions were identical in both integrations. A differential analysis of these two simulations revealed the following. (1) There was a large decrease in evapotranspiration (1.15 mm d−1, roughly 33%) in the deforested region, while the basinwide decrease was only 0.24 mm d−1 (roughly 8%). (2) The associated decrease of precipitation in the deforested (basinwide) regions was about 0.30 (0.168) mm d−1. A precipitation decrease that is smaller than evapotranspiration decrease reflects a mitigating influence of increased moisture convergence, particularly within the boundary layer that gets warmed by the increased surface fluxes of sensible heat and longwave radiation. This implies that precipitation decrease in response to the 1988-level of Amazonian deforestation could be reversed, i.e., reforestation is likely to emerge if the anthropogenic pressures were eliminated and deforestation were forestalled. (3) The changes in the surface wind and rainfall patterns together with increased runoff and surface temperature indicate potential hydrological as well as ecological consequences of deforestation. In our simulations, only small regions of the Amazon basin produced precipitation and circulation changes at 90% or better statistical significance level. This is a consequence of a more realistic deforestation in Amazonia as compared to the total deforestation scenario used in previous studies.

The four major biophysical controls of vegetation which govern land-atmosphere interaction emanate from the ability or vegetation to. (a) evapotranspire (b) trap solar radiation within leaf organizations. (c) regulate evapotranspiration by stomatal control and (d) modify (generally increase) the surface roughness on the scale of turbulent eddies, Simulation studies with General Circulation Models together with a few observational analyses have provided a rational understanding of vegetation-precipitation interaction. In studies with artificially enhanced vegetation-related processes a strong dependence of rainfall on vegetation has been inferred. For Sahelian and other tropical desert-border regions, where evapotranspiration is small, increasing the surface-albedo (desertification) decreases rainfall. When evaportranspiration and or land-surface roughness are increased in some selected regions - a potential effect of vegetation an increase in local rainfall is produced. The above effects both individually and jointly have simulated increased monsoon rainfall over the Indian subcontinent. Modelling studies directed at understanding the relationship between tropical forests and rainfall with realistic models of the biosphere have simulated a warmer and drier climate in response to Amazonian deforestation. Since forests absorb more solar energy and produce much larger evaportranspiration, as well as moisture convergence through the surface-roughness effect, positive feedback effect of forests on precipitation can be expected naturally. Our new simulation experiments not only reaffirmed the above results but also suggested potential global consequences due to the ongoing deforestation. From a synthesis of modeling results of the last decade, it if further inferred that variations in the biosphere-atmospheric interactions play an important role in redistributing continental precipitation to fulfill the survival and growth requirements of different biomes: forests, pasture, agricultural lands, and deserts.

A generalized form of the second-order van Leer transport scheme is derived. Several constraints to the implied subgrid linear distribution are discussed. A very simple positive-definite scheme can be derived directly from the generalized form. A monotonic version of the scheme is applied to the Goddard Laboratory for Atmospheres (GLA) general circulation model (GCM) for the moisture transport calculations, replacing the original fourth-order center-differencing scheme. Comparisons with the original scheme are made in idealized tests as well as in a summer climate simulation using the full GLA GCM. A distinct advantage of the monotonic transport scheme is its ability to transport sharp gradients without producing spurious oscillations and unphysical negative mixing ratio. Within the context of low-resolution climate simulations, the aforementioned characteristics are demonstrated to be very beneficial in regions where cumulus convection is active. The model-produced precipitation pattern using the new transport scheme is more coherently organized both in time and in space, and correlates better with observations. The side effect of the filling algorithm used in conjunction with the original scheme is also discussed, in the context of idealized tests. The major weakness of the proposed transport scheme with a local monotonic constraint is its substantial implicit diffusion at low resolution. Alternative constraints are discussed to counter this problem.

A rain evaporation and downdraft parameterization is designed to complement the cumulus convection scheme of the Goddard Laboratory for Atmospheres General Circulation Model (GLA GCM). The scheme invokes (i) a diagnostic determination of the commencement level of rain-evaporation-induced downdrafts, (ii) a method for calculating downdraft mass fluxes emanating from different levels of the atmosphere, and (iii) an explicitly prescribed overall fraction of rain evaporation within the downdraft. The parameterization was tested with the GATE [GARP (Global Atmospheric Research Program) Atlantic Tropical Experiment] phase III data in a fully prognostic mode and with the entire atmospheric and surface forcings prescribed with data. It was found that the near-surface downdraft cooling largely mitigates the observed surface sensible heating. In the absence of this cooling, the boundary layer must get rid of the surface heat flux by spurious turbulent transport, which becomes significant in simulations tha...

The influence of a cumulus convection scheme on the simulated atmospheric circulation and hydrologic cycle is investigated by means of a coarse version of the GCM. Two sets of integrations, each containing an ensemble of three summer simulations, were produced. The ensemble sets of control and experiment simulations are compared and differentially analyzed to determine the influence of a cumulus convection scheme on the simulated circulation and hydrologic cycle. The results show that cumulus parameterization has a very significant influence on the simulation circulation and precipitation. The upper-level condensation heating over the ITCZ is much smaller for the experiment simulations as compared to the control simulations; correspondingly, the Hadley and Walker cells for the control simulations are also weaker and are accompanied by a weaker Ferrel cell in the Southern Hemisphere. Overall, the difference fields show that experiment simulations (without cumulus convection) produce a cooler and less energetic atmosphere.

The roles of the Critical Cloud Work Function (CCWF) data set and the upper and lower bounds on entrainment by cumulus plumes in the Arakawa-Schubert cumulus parameterization (ASCP) in the GLA GCM (Geller et al., 1988) were investigated in two sets of experiments. It was found that the horizontal and vertical distribution of cumulus heating can be altered in ASCP by adjusting these parameters. These changes can have a strong influence on the vertical structure of condensation heating, water vapor distribution, temperature, and rainfall. The CCWF is an important limiting parameter that controls the onset of different cloud types; increasing the threshold values of CCWF for all clouds tends to concentrate the rainfall into a narrower ITCZ and affects the rainfall during the initial adjustment period.

A new version of the Goddard Laboratory for Atmospheres GCM is utilized to simulate the influence of an observed sea surface temperature anomaly on rainfall and atmospheric circulation. The model can reproduce many essential features of the observed tropical rainfall and circulation anomalies during January-February 1983. Particularly, the model simulates realistic patterns of tropical anomalies of sea level pressure, 200 mb geopotential heights, and horizontal winds at the 200 and 850 mb levels. The model-simulated tropical precipitation anomaly patterns appear realistic, although the precipitation is rather excessive and the atmosphere is too energetic.

A primary concern of CO2-induced warming is the associated rise of tropical (10S-10N) seasurface temperatures (SSTs). GISS Model-E was used to produce two sets of simulations-one with the present-day and one with doubled CO2 in the atmosphere. The intrinsic usefulness of model guidance in the tropics was confirmed when the model simulated realistic convective coupling between SSTs and atmospheric soundings and that the simulated-data correlations between SSTs and 300 hPa moiststatic energies were found to be similar to the observed. Model predicted SST limits: (i) one for the onset of deep convection and (ii) one for maximum SST, increased in the doubled C02 case. Changes in cloud heights, cloud frequencies, and cloud mass-fractions showed that convective-cloud changes increased the SSTs, while warmer mixed-layer of the doubled CO2 contained approximately 10% more water vapor; clearly that would be conducive to more intense storms and hurricanes.

[1] The influence of ice-phase physics (IPP) of hydrometeors was isolated using three 3-year long simulations with the FvGCM employing parameterized cloud microphysics. The Control Case CC had no IPP, whereas the two experiments E1 and E2 invoked IPP with two different hydrometeor-freezing assumptions. Case E1 froze liquid hydrometeors at subfreezing temperatures at detrainment. Case E2 also froze new condensate generated at subfreezing temperatures of the cumulus updrafts. However, melting of falling frozen hydrometeors occurred at the very first encounter with above freezing temperatures in both simulations. Comparative analysis showed discernible differences in cloud and condensation heating climatologies of these simulations. Specifically, IPP influenced convective detrainment at mid- and deep-levels in accord with TOGA-COARE observations. The study suggests that IPP can mitigate less-than-observed mid-level clouds and over-abundance of deep clouds and might invigorate cumulus-induced downdrafts.

In all the atmospheric general circulation models (GCMs) at the Goddard Laboratory for Atmospheres (GLA), the influence of oceanic salinity on the saturation vapor pressure of seawater is ignored. Since the relative humidity in the oceanic boundary layer is generally high while the saturation vapor pressure of seawater is lowered by salinity, its neglect could have a nontrivial influence on the near-surface specific humidity gradient, a primary determinant of oceanic evaporation. Such an approximation might effect the simulated circulation and rainfall systematically. To evaluate this idea, we carried out a 5-yr-long salinity simulation (S) with the GLA GCM in which the influence of salinity on the saturation vapor pressure of seawater was included. Corresponding to this, a control simulation (C) with the GLA GCM in which the salinity effect was ignored was also available. Analyses of S-minus-C fields have shown some evidence of discernible systematic errors in the global evaporation, boundary la...

Experiments were conducted from 1983 to 1985 to test the hypothesis that rate of dry matter accumulation by maize (Zea mays L.) during grain filling can be enhanced by an increase in assimilate demand for grain filling (i.e., sink strength).The sink strength of maize plants grown in an outdoor hydroponic system was varied independently of the source strength by manipulating the plant spacing during the period in which final kernel number is established. The crop growth rate during grain filling, the dry matter of leaves, stems, ears and roots, and grain yield components were determined. In all 3 yr the crop growth rate during grain filling of plants that had been growing at a 20 000 plants ha−1 spacing for variable periods and were returned to the control density of 80 000 plants ha−1 at the start of the grain-filling period was lower than that of plants grown continuously at a spacing of 80 000 plants ha−1. In 1985, plants grown at 20 000 plants ha−1 from 3 wk preanthesis until 2 wk postanthesis and at 80 000 plants ha−1 thereafter had 50% more kernels per plant than the control plants. However, the net photosynthesis during grain filling was not increased; in fact it was somewhat lower. Final grain yield was not significantly different, mainly due to greater translocation from the stems to the grain in the spaced plants than in the controls. These studies indicate that maize growing in a nonlimiting below-ground environment is not sink limited. Hence adding sink capacity by maintaining kernel number while increasing plant density or by adding more kernels per plant would not appear to be a promising route for raising the yield potential.Key words: Sink strength, hydroponics, plant spacing, kernel number, yield components

Otter faeces were collected at monthly intervals from around two lakes near the River Dee in Aberdeenshire in 1975 and 1976. They were analysed to show the frequency of occurrence of identifiable undigested items and also the relative bulk of these different items. Statistical differences were recorded in frequency of occurrence. The main food was eel in both years with small perch also important in January to June and amphibia in the spring. A reduction in the frequency of eel in the faeces was associated with fewer observations of otters.

Evaporation rates beneath maize canopies were measured using an intact soil core technique. Early in the growing season evaporation rates were periodically high (4.0 mm∙day−1) following rain, but declined rapidly. At full crop cover, when energy supply normally limits evaporation, significant differences in evaporation were detected between canopies with leaf area indices of 3.0 and 4.0. Key words: Evaporation measurement, energy supply, Zea mays L., leaf area, soil evaporimeter, lysimeter

Maize (Zea mays L.) was grown outdoors hydroponically and in soil to compare yields in the two systems and to determine the extent to which soil temperature and plant nutrition limit yield of soil-grown plants. The hydroponic system consisted of 22.5-L plastic pails filled with "Turface" to which nutrient solution was added at least twice daily. In all 3 yr dry-matter accumulation throughout the growing season was greater on the hydroponic system than in well-fertilized, irrigated sandy-loam soil when planting pattern and density were the same. Maximum aboveground dry matter and grain dry matter on the hydroponic system were 25.8 and 12.2 Mg ha−1, respectively. It is apparent that there is a soil-based constraint that limits aboveground dry-matter production to 75–85% of the potential with the aboveground environment in the region. Grain yield appears to be limited to a lesser extent. To determine the effect of root-medium temperature, growth in pails buried in the soil was compared to that in soil and in pails placed on the soil surface. Although the temperature of the buried pails was consistently lower than that in the aboveground pails and in the soil, dry matter accumulation was similar to that in the aboveground pails indicating that soil temperature was not a cause of the lower yield of the soil-grown plants. There was no evidence that plants growing on the highly fertilized soil were nutrient limited at any growth stage. Other studies have indicated that transient water stress on soil-grown plants will not explain the difference in growth on the two systems. Key words: Maize, hydroponics, soil limitations, soil temperature, nutrition

Determination de la conductance totale de la vapeur d'eau pour une culture, application a la prevision de rendement. Etude theorique et etude au champ sur haricots par mesures thermometriques IR

The diffusion of 59Fe in a commercial 3% silicon iron alloy has been measured over the temperature range 967 to 1416°c by the residual activity method. The results are summarized by the equation: These results agree favourably with previous low temperature measurements made on an alloy of slightly different composition.

A simple procedure is reported for the rapid dehydration of light microscopy specimens using 2,2 dimethoxypropane (DMP). This procedure offers the advantages of economy and reduction in dehydration time without a loss of staining or morphological quality when compared to conventionally prepared light microscopy tissues.

A theoretical treatment is given of the sintering of cavities by grain-boundary diffusion, assuming vacancies to be annihilated at randomly distributed sinks. Satisfactory agreement is obtained with previously published experimental data.

Legionella micdadei is a recently described opportunistic pulmonary pathogen that produces an acute, suppurative pneumonia in patients receiving steroid therapy. Most prospective diagnoses have been made by open lung biopsy. We present a case in which the diagnosis was made from cytologic material. The clinicopathologic features of L. micdadei pneumonia are discussed, and criteria for diagnosis from cytologic specimens are presented.

Thoracic manifestations of extramedullary hematopoiesis (EMH) are well known clinically, radiologically and pathologically; it is generally confirmed histologically by open biopsy or postmortem examination. We report a case of EMH diagnosed by percutaneous fine needle aspiration (FNA) in a patient with long-standing, acquired, sideroblastic anemia. The aspirate was very cellular and composed of normal bone marrow elements with an erythroid to myeloid cell ratio of 3 to 1. Megakaryocytes were abundant but constituted less than 1% of the total cell population. This case illustrates that the diagnosis of EMH is possible by FNA and that thoracotomy for diagnostic purposes can be circumvented.