Flat Grass Research Articles

A New Species of Comones Noyes and Woolley (Hymenoptera: Encyrtidae), A Parasitoid of Flat Grass Scale, Aclerda takahashii Kuwana (Hemiptera: Aclerdidae), A New Pest on Sugarcane in Florida

Comones dulcis Mottern new species is described from specimens reared from flat grass scale, Aclerda takahashii Kuwana, on sugarcane in Palm Beach County, Florida. The new species exhibits considerable size variation and apparent allometric scaling of body parts that are often used for encyrtid species diagnosis. Therefore, both morphological and molecular data are presented to describe and diagnose the species. Photographs of the congeners C. ferrierei (Burks) and C. gastron (Walker)_ are included for comparison. Prospects for incorporating C. dulcis into a biological control program targeting flat grass scale are discussed.

The Economic Impact and Dynamical Fluctuations Caused by The Flat Grass Scale Population, Aclerda Takahashii Kuwana (Hemiptera, Coccomorpha: Aclerdidae) Infesting Sugarcane in Alexandria, Egypt

The flat grass scale, Aclerda takahashii Kuwana, (Hemiptera, Coccomorpha: Aclerdidae) since its record for the first time in 1990 infesting sugarcane in Alexandria, Egypt, very little is known or published about the economic impact caused by this species, its seasonal fluctuation and assessed damage in sugarcane crop. Thus, the adopted study is focused in the palatability and impact caused by this pest as well as its annual dynamical fluctuation. Data obtained revealed that the estimated fluctuating densities of A. takahashii individuals on the stem of sugarcane plant, throughout both the following growing seasons of 2014-2015 and 2015-2016 proved two overlapping peaks for each. The obtained results also clarified that Aclerda takahashii mainly prefer the internodes of lower and medium parts of the sugarcane stem, compared with its upper part. Regarding the impact of Aclerda takahashii on the TSS% (Brix), the obtained results showed that A. takahashii infestation reduce the Brix mean value (TSS%) according to its incidence level which could be of economic concern.

Affective Outcomes of Group versus Lone Green Exercise Participation.

‘Green exercise’ (being physically active within a natural environment) research has examined the influence of environmental setting on health and wellbeing-related exercise outcomes. However, it is not known whether social exercise settings influence green exercise-associated changes in mood, self-esteem, and connection to nature. This study directly compared outcomes of participating in green exercise alone compared to in a group. Using repeated measures, counterbalanced and randomized-crossover design, participants (n = 40) completed two 3 km runs around sports fields. These fields had a relatively flat grass terrain, predominant view of trees, and open grassland. On one occasion participants ran alone and on the other they ran in a group of 4–5 participants. Questionnaire measures of mood, self-esteem, and connection to nature were completed immediately pre- and post-run. Across all of the measures, two-way mixed ANOVAs found that there were statistically significant effects for time but not for time-by-condition interactions. The simplest interpretation of this finding is that social setting does not influence individuals’ attainment of the psychological outcomes of green exercise participation. However, we discuss the possibility that more complex processes might underpin this finding.

A key to the flat grass scale genus Nipponaclerda (Hemiptera, Coccomorpha, Aclerdidae).

The flat grass scale genus Nipponaclerda comprises four species, native to Central and East Asia. Nipponaclerdabiwakoensis has been introduced to the United States and is considered a serious pest of Phragmitesaustralis, the common reed. Heavy infestations of N.biwakoensis in coastal marshes of Louisiana have coincided with extensive die-off of reeds. In this article, dichotomous identification keys to the genera of Aclerdidae and to the species of Nipponaclerda are provided, allowing for accurate identification of species found in the native and invasive range.

Measurement and Analysis of Near-Ground Propagation Models under Different Terrains for Wireless Sensor Networks.

The propagation model is an essential component in the design and deployment of a wireless sensor network (WSN). Although much attention has been given to near-ground propagation models, few studies place the transceiver directly on the ground with the height of antennas at the level of a few centimeters, which is a more realistic deployment scenario for WSNs. We measured the Received Signal Strength Indication (RSSI) of these truly near-ground WSNs at 470 MHz under four different terrains, namely flat concrete road, flat grass and two derived scenarios, and obtained the corresponding path loss models. By comprehensive analysis of the influence of different antenna heights and terrain factors, we showed the limit of existing theoretical models and proposed a propagation model selection strategy to more accurately reflect the true characteristics of the near-ground wireless channels for WSNs. In addition, we implemented these models on Cooja simulator and showed that simplistic theoretical models would induce great inaccuracy of network connectivity estimation.

БИОЛОГИЧЕСКИ АКТИВНЫЕ ВЕЩЕСТВА НЕКОТОРЫХ ВИДОВ РОДА LATHYRUS L.

Background . Many of perennial and annual Lathyrus species have economic significance and are used of the world's agriculture. They are often cultivated as forage crops. An important role in developing new forage crops is given to selection for an increased quality of green biomass. Studying biologically active substances (BAS) in green matter of different Lathyrus varieties is needed to search for accessions with as high nutritional value as possible that can serve as sources of BAS. Materials and methods . Thirty-five accessions representing 6 species (L. sativus L., L. vernus (L.) Bernh., L. latifolius L., L. tuberosus L., L. linifolius (Reichard) Bassler, L. sylvestris L.) of the genus Lathyrus L. from the VIR collection were studied. BAS were detected in the green biomass of the accessions in an early phase of bean ripening. The accessions were analyzed by VIR-approved methods (Ermakov et al., 1987). The qualitative and quantitative analyses of phenolic compounds was performed by means of gas chromatography with mass spectrometry (GC-MS Agilent 6850, USA). Results. The content of ascorbic acid, carotenoids, carotenes, в-carotene, chlorophylls a and b, phenolic compounds in the Lathyrus species was studied for the first time. Significant interspecific and intervarietal differences were identified in the BAS content of green matter. The range of variability was as follows: ascorbic acid: 39.0-133.0; chlorophylls a and b: 55.5-365.5; carotenoids: 10.6-44.5; carotenes: 3.630.0; в-carotene: 2.6-24.8; phenols: 4.4-199.4 mg/100g of raw material. The highest rates were observed in L. linifolius and L. latifolius accessions. Conclusion. Green biomass of the studied Lathyrus accessions was balanced in the BAS content and showed high nutritive value. All studied species are of interest for forage crop breeding. The accessions of flat pea (L. sylvestris) and grass pea (L. sativus) are promising for practical use in feed production. L. linifolius and L. latifolius have good prospects as sources of biologically active substances.

Unsupervised Fine Land Classification Using Quaternion Autoencoder-Based Polarization Feature Extraction and Self-Organizing Mapping

We propose an unsupervised polarimetric synthetic aperture radar (PolSAR) land classification system consisting of a series of two unsupervised neural networks, namely, a quaternion autoencoder and a quaternion self-organizing map (SOM). Most of the existing PolSAR land classification systems use a set of feature information that humans designed beforehand. However, such methods will face limitations in the near future when we expect classification into a large number of land categories recognizable to humans. By using a quaternion autoencoder, our proposed system extracts feature information based on the natural distribution of PolSAR features. In this paper, we confirm that the information necessary for land classification is extracted as the features while noise is filtered. Then, we show that the extracted features are classified by the quaternion SOM in an unsupervised manner. As a result, we can discover even new and more detailed land categories. For example, town areas are divided into residential areas and factory sites, and grass areas are subcategorized into furrowed farmlands and flat grass areas. We also examine the realization of topographic mapping of the features in the SOM space.

Short and flat grass preferred by adults of the endangered dragonfly Sympetrum pedemontanum elatum (Odonata: Libellulidae)

Sympetrum pedemontanum (Muller in Allioni) (Odonata: Libellulidae) is widely distributed across the Eurasian continent and its neighboring islands. However, the populations of its subspecies S. pedemontanum elatum (Selys) in Japan have been rapidly decreasing with the loss of habitats in rural and suburban areas since the 1970s. For the conservation of this subspecies, which is now listed as endangered in many prefectures, it is important to understand the habitat preferences of the adults. Previous studies indicate that adult males of this species tend to fly on the flat surface of rice paddy fields. Thus, we hypothesized that they preferred short and flat grass. Field experiments in the Sakasegawa River, Hyogo Prefecture, Japan, showed that adult S. p. elatum significantly preferred the trimmed grass of Phragmites japonicus to untreated shaggy grass, regardless of sex. Our results indicate the importance of grass management for the conservation of this species, not only in and around paddy fields but also in fluvial habitats, which are abundant in Japan.

Monitoring thickness and volume changes of the Dongkemadi Ice Field on the Qinghai-Tibetan Plateau (1969–2000) using Shuttle Radar Topography Mission and map data

This paper presents the first measurement of multi-decadal thickness and volume changes (1969–2000) of the Dongkemadi Ice Field (DIF) in the Tanggula Mountains, central Qinghai-Tibetan Plateau, China, using multi-source remote sensing data. These include the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) acquired in February, 2000, a DEM generated by digitising analogue topographic maps from 1969, and Landsat ETM+ imagery from 2000. Digital glacier outlines and GIS-based processing were used to calculate an elevation difference map to evaluate the relative elevation error of these two DEMs over ice-free areas. This method was also used to identify regions of glacier elevation thinning and thickening corresponding to glacier mass loss and gain. Analysis of 67,520 points on flat grass and rock terrain surrounding the DIF, with a slope less than 25°, showed a mean elevation difference of –0.90 m and a standard deviation of 5.58 m. A thickness change error within ±6 m was estimated. Between 1969 and 2000, 76.51% of the whole DIF area appeared to be thinning while 23.49% showed thickening. The average glacier surface thinning was –12.58 m with a standard deviation of 18.29 m and the estimated volume loss was 1.17 km3. The standard deviation of volume change was 0.0006 km3 over the DIF. A thinning rate up to 0.41±0.194 m a−1 or 0.038 km3 a−1 for the volume loss was observed for the whole ice field, which seems to be evidence for the ongoing retreat of glaciers on the Qinghai-Tibetan Plateau. It was found that the spatial thickness change pattern derived from the remote sensing method was consistent with the thickness change results of the Small Dongkemadi Glacier (SDG) from field measurements. The estimated error of the annual thickness change rate was on the order of 5%. The relationship between elevation change and absolute glacier elevation over typical glaciers was also analysed, showing considerable variability. These changes have possibly resulted from increased temperature and decreased precipitation in this region.

Inaccurate Representation of the Ground Surface beyond a Texture Boundary

The sequential-surface-integration-process (SSIP) hypothesis was proposed to elucidate how the visual system constructs the ground-surface representation in the intermediate distance range (He et al, 2004 Perception 33 789-806). According to the hypothesis, the SSIP constructs an accurate representation of the near ground surface by using reliable near depth cues. The near ground representation then serves as a template for integrating the adjacent surface patch by using the texture gradient information as the predominant depth cue. By sequentially integrating the surface patches from near to far, the visual system obtains the global ground representation. A critical prediction of the SSIP hypothesis is that, when an abrupt texture-gradient change exists between the near and far ground surfaces, the SSIP can no longer accurately represent the far surface. Consequently, the representation of the far surface will be slanted upward toward the frontoparallel plane (owing to the intrinsic bias of the visual system), and the egocentric distance of a target on the far surface will be underestimated. Our previous findings in the real 3-D environment have shown that observers underestimated the target distance across a texture boundary. Here, we used the virtual-reality system to first test distance judgments with a distance-matching task. We created the texture boundary by having virtual grass- and cobblestone-textured patterns abutting on a flat (horizontal) ground surface in experiment 1, and by placing a brick wall to interrupt the continuous texture gradient of a flat grass surface in experiment 2. In both instances, observers underestimated the target distance across the texture boundary, compared to the homogeneous-texture ground surface (control). Second, we tested the proposal that the far surface beyond the texture boundary is perceived as slanted upward. For this, we used a virtual checkerboard-textured ground surface that was interrupted by a texture boundary. We found that not only was the target distance beyond the texture boundary underestimated relative to the homogeneous-texture condition, but the far surface beyond the texture boundary was also perceived as relatively slanted upward (experiment 3). Altogether, our results confirm the predictions of the SSIP hypothesis.

Effects of microenvironment on net photosynthetic rate and growth of four tropical species in the La Mesa watershed

Seedlings of four tree species (Bischofia javanica, Dracontomelon dao, Erythrina orientalis, and Pterocarpus indicus) were planted in flat and sloping grassland in plantation sites established in May 2002 in the La Mesa watershed, Philippines. Tree growth and net photosynthetic rate (PN) were monitored. The height, diameter at the root collar, and PN of the four species grown in the sloping grass site were larger than those of seedlings grown in the flat grass site. In addition, soil moisture contents in the sloping grass site were higher than those of the flat grass site. Growth of the four species was probably strongly associated with microenvironments (e.g. air temperature) in both tested sites.

Nitrous acid formation in the urban atmosphere: Gradient measurements of NO2 and HONO over grass in Milan, Italy

The source of nitrous acid, HONO, in the troposphere remains uncertain, even after two decades of research. It is currently believed that HONO is formed by heterogeneous conversion of NO2 on either the ground or the aerosol surface. While this conversion has been studied in the laboratory, few atmospheric studies have been reported. Here we present the first simultaneous determination of the vertical gradients and fluxes of HONO, its precursor NO2, and SO2 over a flat grass surface in the polluted atmosphere. The measurements were performed in Milan, Italy, during the Limitation of Oxidant Production/Pianura Padana Produzione di Ozono (LOOP/PIPAPO) study in summer 1998, using differential optical absorption spectroscopy. While deposition of NO2 onto the ground was frequently observed, heterogeneous HONO formation was much smaller than expected. We can explain our observation by a mechanism that consists of a combination of NO2 and HONO deposition, and a heterogeneous conversion of NO2 to HONO on the ground. The compensation point for deposition and formation of HONO is characterized by a HONO/NO2 ratio of ∼0.03, indicating that only one HONO molecule is released into the gas phase for every 33 NO2 molecules deposited. Our measurements also show that direct emission of HONO is an important source in strongly polluted areas.

Stable Atmospheric Boundary-Layer Experiment in Spain (SABLES 98): A Report

This paper describes the Stable Atmospheric Boundary Layer Experiment in Spain (SABLES 98), which took place over the northern Spanish plateau comprising relatively flat grass- land, in September 1998. The main objectives of the campaign were to study the properties of the mid-latitude stable boundary layer (SBL). Instrumentation deployed on two meteorological masts (of heights 10 m and 100 m) included five sonic anemometers, 15 thermocouples, five cup anemometers and three propeller anemometers, humidity sensors and radiometers. A Sensitron mini-sodar and a tethered balloon were also operated continuously. A triangular array of cup anemometers was installed to allow the detection of wave events. Two nocturnal periods analysed on 14-15 and 20-21 September are used to illustrate the wide-ranging characteristics of the SBL.

Seasonal variability of ozone dry deposition under southern European climate conditions, in Portugal

Ozone dry deposition measurements were carried out during approximately one year over a flat grass field in Portugal. The results show prominent diurnal and seasonal patterns in deposition flux, dry deposition velocity and surface resistance, especially for the daytime period. Dry deposition velocities vary diurnally from a minimum of 0.1 cm s −1, during the night to a maximum of 0.2–0.5 cm s −1 during the day. The observed canopy resistance ( R c) varies from values higher than 500 s m −1, at night, to a minimum of 200 s m −1, around noon. Seasonal variation is characterised by daytime R c values much larger in summer than in winter and spring, while nighttime values do not show any evident seasonal pattern. This behaviour can be ascribed to the stomatal intake, which represents the most important controlling factor on ozone dry deposition. The Wesely parameterisation scheme of surface resistance predicts R c diurnal cycles reasonably well. However, the observed canopy resistance seasonal cycle is completely different from Wesely predictions, since season parameters in Wesely's parameterisation were defined for a vegetation growing cycle different from that prevailing in our conditions.

Turbulence in a Katabatic Flow

Turbulence measurements performed in a stable boundary layer over the sloping ice surface of the Vatnajokull in Iceland are described. The boundary layer, in which katabatic forces are stronger than the large-scale forces, has a structure that closely resembles that of a stable boundary layer overlying a flat land surface, although there are some important differences. In order to compare the two situations the set-up of the instruments on an ice cap in Iceland was reproduced on a flat grass surface at Cabauw, the Netherlands. Wind speed and temperature gradients were calculated and combined with flux measurements made with a sonic anemometer in order to obtain the local stability functions φm and φh as a function of the local stability parameter z/L. Unlike the situation at Cabauw, where φm was linear as a function of z/L, in the katabatically forced boundary layer, the dependence of φm on stability was found to be non-linear and related to the height of the wind maximum. Thermal stratification and the depth of the stable boundary layer however seem to be rather similar under these two different forcing conditions.

Sudden Change of Surface Inversion of Air Temperature on Suburban Area in the Chiba Prefecture

Vertical profile of air temperature is measured by radiosonde set on anchored balloon at a winter night, 3-4 December 1979, under the condition of clear sky and gentle wind. The observations were made at four points distributed in about 15km distance, in northwestern Chiba Prefecture (Fig. 1).Surface inversion appeared before sunset (about 15:30JST). Intensity of inversion increased to midnight and the depth of inversion layer reached 50-75m at midnight. Between 0 to 1JST temperature profile showed sudden change; strong inversion layer is elevated to 50-100m hight and ground based isothermal layer appeared under 50m bight (Fig. 2, 3). The similer change of temperature profile appeared at three suburban observation points except at one point placed in flat grass field. Concentration of NO and NO2 are high within the inversion layer and their vertical profile show simultaneous change with that of inversion (Fig. 4, 5).It is shown by wind field analysis, that the cold northern wind causes the change of temperature profile. The wind is a part of land breeze from Kanto Plain to the Tokyo Bay (Fig. 6, 7). These phenomena appeared at 34 nights during December of 1975-1979 (Table 1, 2 and Fig. 8), which correspond to the occurence frequency of about a half number of nights with clear sky and gentle wind.

Effect of homogeneous and heterogeneous surface roughness on heavier-than-air gas dispersion

The effect of homogenous and heterogenous roughness on entrainment and dispersion rates was assessed by collecting experimental data in a boundary-layer wind tunnel. Point and area sources were simulated at a 1:100 model scale with homogenous surface roughness configurations ranging from flat grass land to an urban area. Heterogenous roughness was simulated in the form of a typical refinery tank farm and typical process unit. Relative gas densities (source gas to ambient air) varied from 1 to 4. Concentrations of a tracer gas were measured and analyzed to determine the horizontal and vertical plume spread rates, rate of air entrainment as well as the variation of maximum ground-level concentration with roughness size. The results of the study demonstrated that large roughness elements can significantly reduce the concentrations and that the entrainment relations presently in use for homogenous roughness configurations do adequately model the process. For heterogenous roughness configurations, the entrainment and dispersion rates appeared to be site specific and not well modeled using existing techniques.

Effect of homogeneous and heterogeneous surface roughness on heavier-than-air gas dispersion

The effect of homogenous and heterogenous roughness on entrainment and dispersion rates was assessed by collecting experimental data in a boundary-layer wind tunnel. Point and area sources were simulated at a 1:100 model scale with homogenous surface roughness configurations ranging from flat grass land to an urban area. Heterogenous roughness was simulated in the form of a typical refinery tank farm and typical process unit. Relative gas densities (source gas to ambient air) varied from 1 to 4. Concentrations of a tracer gas were measured and analyzed to determine the horizontal and vertical plume spread rates, rate of air entrainment as well as the variation of maximum ground-level concentration with roughness size. The results of the study demonstrated that large roughness elements can significantly reduce the concentrations and that the entrainment relations presently in use for homogenous roughness configurations do adequately model the process. For heterogenous roughness configurations, the entrainment and dispersion rates appeared to be site specific and not well modeled using existing techniques.

Wear striation direction on primate teeth: A scanning electron microscope examination

Two experimental methods were used to produce wear striations in one direction on unworn teeth. These include: (1) sliding 22 American Indian (Juntunen site, Michigan; Late Woodland) newly erupted incisors, by hand, across a flat grass surface covered with fine loose sand; and (2) using a unidirectional motor driven mechanical wear machine to draw 56 modern human dental extractions across a flat glass surface covered with silicon carbide powder of different grit sizes. A scanning electron microscope examination of individual wear striation morphology indicates that these wear striations begin with broad pits and have extending grooves that become narrower; characteristics that indicate the motion of wear. Patterns of wear striations on the worn dentitions of American Indians (Juntunen site) and the paleocene primate Phenacolemur pagei show similar characteristics and correspond to the buccal phase of mastication when the mandible is drawn upward, forward and slightly medially into centric occlusion. The data provided by this study can be used to test competing hypotheses concerning the direction of mandibular movement during mastication and food preparation.

The deposition of particles on moss and grass surfaces

Measurements have been made in a large wind tunnel of transport of particles of various sizes to the surface of the moss Hypnum cupressiforme and Italian rye grass. The particles were selected to cover the range in size which is likely to be encountered in natural and pollution conditions in the field. Advantage was taken of radioactive counting techniques to measure the small concentrations of particles both in the gas phase and deposited on surfaces. The methods of radioactive tagging of the particles are outlined and the sampling techniques used to measure deposition onto flat grass and moss surfaces and suspended moss bags are described. The measurement of the effect of particle size and wind speed on the deposition of particles to moss bags showed that in the range of wind speeds normally encountered, the larger particles in the atmosphere are much more efficiently collected than the smaller fraction. However, change in wind speed or particle size has almost the same proportional effect on the collection characteristics of moss bags and extended flat surfaces of moss or grass. The results show that moss bags can be used as a monitor of dry particulate input to extended crop and soil surfaces. It is an unsatisfactory monitor of the particulate content of air because its efficiency is very dependent on particle size and wind velocity.