Local heating of human skin by millimeter waves: a kinetics study

Heating rates of human skin exposed locally to 42.25 GHz mm waves, coming from a waveguide (WG) opening or a YAV device designed for therapeutic application, were studied in vivo using infrared (IR) thermography. For both radiators, the power density distribution was described by a circularly symmetrical Gaussian type function on the exposed skin surface. Insertion of a small thermocouple (d = 0.1 mm) in the exposed area did not produce any significant artifact, either in the power density distribution or kinetics measurement, providing it was perpendicular to the E vector. The heating kinetics in the skin exposed with either the WG opening or the YAV device were well fitted to solutions of the 2-D bio-heat transfer equation for homogeneous tissue. Changes in irradiating beam size (1-8 mm) had no detectable effect on the initial (0.3-3.0 s) phase of the heating kinetics. However, the amplitude of the kinetics decreased substantially with decreasing the beam size. As the temperature rise in the time interval necessary for reliable measurement of the initial temperature rise rate was very small, an accurate experimental determination of specific absorption rate (SAR) becomes practically impossible at the low intensities normally used in our experiments. The correct SAR values may be found from fitting of the model to the heating kinetics. Bioelectromagnetics 24:571-581, 2003.     

A four coil exposure system (tetracoil) producing a highly uniform magnetic field

We propose a magnetic field exposure system (tetracoil) for in vitro and in vivo experiments, composed of two couples of circular coils satisfying a spherical constraint, whose characteristics are chosen in order to maximize the uniformity region of the magnetic field. Analytical calculations and computer simulations show that our system, as compared to the other most largely used magnetic field exposure systems, represents an optimal compromise in terms of field uniformity, accessibility for biological experiments, and ratio between overall dimension and uniformity region.     

Mass distributions of a macromolecular assembly based on electrospray ionization mass spectrometric masses of the constituent subunits

Macromolecular assemblies containing multiple protein subunits and having masses in the megadalton (MDa) range are involved in most of the functions of a living cell. Because of variation in the number and masses of subunits, macromolecular assemblies do not have a unique mass, but rather a mass distribution. The giant extracelular erythrocruorins (Ers), ∼ 3.5 MDa, comprized of at least 180 polypeptide chains, are one of the best characterized assemblies. Three-dimensional reconstructions from cryoelectron microscopic images show them to be hexagonal bilayer complexes of 12 subassemblies, each comprised of 12 globin chains, anchored to a subassembly of 36 nonglobin linker chains. We have calculated the most probable mass distributions forLumbricus andRiftia assemblies and their globin and linker subassemblies, based on theLumbricus Er stoichiometry and using accurate subunit masses obtained by electrospray ionization mass spectrometry. The expected masses ofLumbricus andRiftia Ers are 3.517 MDa and 3.284 MDa, respectively, with a possible variation of ∼ 9% due to the breadth of the mass distributions. TheLumbricus Er mass is in astonishingly good agreement with the mean of 23 known masses, 3.524 ± 0.481 MDa.     

Spatial distribution of Culicoides species in Portugal in relation to the transmission of African horse sickness and bluetongue viruses

Surveillance of Culicoides (Diptera: Ceratopogonidae) biting midge vectors was carried out at 87 sites within a 50 x 50 km grid distributed across Portugal, using light trap collections at the time of peak midge abundance. Culicoides imicola (Kieffer) made up 66% of the 55 937 Culicoides in these summer collections. It was highly abundant in the central eastern portion of Portugal, between 37 degrees 5' N and 41 degrees 5' N, and in a band across to the Lisbon peninsula (at around 38 degrees 5' N). Of all the complexes, its distribution was most consistent with that of previous outbreaks of Culicoides-borne disease, suggesting that it may remain the major vector in Portugal. Its distribution was also broadly consistent with that predicted by a recent climate-driven model validating the use of remote sensing datasets for modelling of Culicoides distribution. Adult C. imicola were found to have overwintered at 12 of 20 sites re-surveyed in winter but it did so in very low numbers. Culicoides obsoletus (Meigen) and Culicoides pulicaris (Linnaeus) complex midges were widespread despite their low summer abundance. The observed coincidence of high abundances of C. imicola and high abundances of C. pulicaris in summer lead us to suggest that C. imicola could bring African horse sickness virus or bluetongue virus into contact with C. pulicaris and the latter complex, together with C. obsoletus, could then transmit these viruses across much wider areas of Europe. The fact that adult C. pulicaris are present in high abundances in winter may provide a mechanism by which these viruses can overwinter in these areas.     

Importance of topography and soil texture in the spatial distribution of two sympatric dipterocarp trees in a Bornean rainforest

Relationships between spatial distributions and site conditions, namely topography and soil texture, were analyzed for two congeneric emergent trees, Dryobalanops aromatica and Dryobalanops lanceolata (Dipterocarpaceae), in a tropical rainforest in Sarawak, East Malaysia. A 52-ha permanent plot was divided into 1300 quadrats measuring 20m×20m; for each Dryobalanops species, the number and total basal area of trees 1cm in d.b.h. were compared among groups of quadrats with different site conditions. Because spatial distributions of both Dryobalanops and site-condition variables were aggregated, Monte-Carlo permutation tests were applied to analyze the relationships. Both single and multifactor statistical tests showed that the density and basal area distributions of the two species were significantly non-random in relation to soil texture and topographic variables. D.aromatica was significantly more abundant at higher elevations, in sandy soils, and on convex and steep slopes. In contrast, D.lanceolata preferred lower elevations and less sandy soils. In the study plot, there were very few sites (3 of 1150 quadrats tested) where the models of Hayashis method predicted the co-occurrence of the two species. These results suggest that between-species differences in habitat preferences are so large that they alone explain the spatially segregated distributions of these two species within the 52-ha study plot.     

Detection of sequences in the cerebellar cortex: numerical estimate of the possible number of tidal-wave inducing sequences represented

The two major cortices of the brain--the cerebral and cerebellar cortex--are massively connected through intercalated nuclei (pontine, cerebellar and thalamic nuclei). We suggest that the two cortices co-operate by generating precise temporal patterns in the cerebral cortex that are detected in the cerebellar cortex as temporal patterns assembled spatially in the mossy fibers. We will begin by showing that the tidal-wave mechanism works in the cerebellar cortex as a read-out mechanism for such spatio-temporal patterns due to the synchronous activity they generate in the parallel fiber system which drives the Purkinje cells--the output neurons of the cerebellar cortex--to fire action potentials. We will review the anatomy of the mossy fibers and show that within a "beam", or "row" of cerebellar cortex the mossy fibers in principle could embed a vast number of tidal-wave generating sequences. Based on anatomical data we will argue that the cerebellar mossy fiber-granule cell-Purkinje cell system can potentially detect and--through learning--select from an enormous number of spatio-temporal patterns.     

Characteristics and conservation priority of threatened plants in the Yangtze valley

One hundred and twenty-seven threatened species listed in the ChinaPlant Red Data Book were found in the Yangtze valley. One-third of them belongedto four families with high economic value, including Pinaceae, Magnoliaceae,Lauraceae and Ranuculaceae. Of all the plants, 66.9% grew in forests and 71.7%were threatened with damage to habitats. The threatened plants in the studiedregion formed a geographical pattern with two large and six small distributioncenters. The two large centers were in the high mountains in western Sichuan andnorthern Yunnan or around the Sichuan Basin. The six small centers were situatedin fragmented montane forests in the eastern part of the Yangtze valley. Todetermine a plant's threat category, the number of populations 10 wasused as the basic criterion as accorded with the China Plant Red Data Book. Thethreatened plants in the valley could be divided into five ranks of priority forconservation. The plants in the first rank comprised eight species endemic tothe valley, with only one population, which should be first preserved. It wasconcluded that human activity was the main factor threatening the survival ofplants, and protecting forests had been the most effective approach in savingthe threatened plants in the valley.     

Environmental factors influencing the distribution of rRNA from Verrucomicrobia in soil

The Verrucomicrobia constitute a newly discovered division of the Bacteria identified as a numerically abundant component of soil microbial communities in numerous sites around the world. The relative abundance of rRNA from Verrucomicrobia was investigated in the soil to examine the influence of specific environmental factors on the distribution of Verrucomicrobia and to better understand the distribution of this group in terrestrial ecosystems. The abundance of the verrucomicrobial rRNA was determined by using a novel oligonucleotide probe that is specific for verrucomicrobial 16S rRNA. The abundance of verrucomicrobial 16S rRNA in soil microbial communities was determined in relation to plant community composition and soil management history over a period of 2 years. Additional samples were analyzed to determine if verrucomicrobial rRNA relative abundance changes in relation to either soil depth or soil moisture content. The Verrucomicrobia composed 1.9+/-0.2% of the microbial community rRNA present in the 85 soil samples examined. The distribution of verrucomicrobial rRNA in the soil reveals that Verrucomicrobia are significantly affected by environmental characteristics that change in relation to time, soil history, and soil depth, and reveals that a statistically significant amount of the variation in verrucomicrobial rRNA abundance can be explained by changes in soil moisture content.     

Comparative Biogeography of Grasshoppers (Orthoptera: Acrididae) in North America and Siberia: Applications to the Conservation of Biodiversity

The objective of this study was to apply knowledge of holarctic grasshopper biogeography in representative, temperate ecosystems (Russia, South Siberia, Sayans region; 685,000km² and USA, Wyoming; 272,000km²) to develop a comparative basis for understanding and conserving insect biodiversity. Maps of species distributions and vegetation zones were digitized, and a Geographic Information System was used to identify habitats with the greatest biodiversity and to characterize this diversity as a function of selected attributes. With respect to subfamilies, the greatest differences were in cold, mesic zones, where gomphocerines and melanoplines were dominant in Sayans and Wyoming, respectively. In terms of mobility, the Sayans has more flightless species and individuals, with the taiga supporting the greatest frequency of flightless acridids in both countries. With regard to feeding types, the diversity and richness of graminivores and forbivores were similar in the two regions, but mixed feeders were much more frequent in Wyoming. In the Sayans and Wyoming, pest species were most common in boreal and prairie zones, respectively. Ecoregions with a high diversity of pests also supported a high diversity of rare species. Shrub and desert zones supported many rare species in both countries. Thus, in terms of conservation, the Sayans' acridofauna appears to be at greater risk in terms of ecological vulnerability; acridid biodiversity is dispersed among habitats, with high frequencies of flightless and oligophagous species. The acridofauna of Wyoming could be conserved in fewer habitats than in the Sayans, but these habitats are subject to considerable human disturbance.     

西双版纳人工林林窗光照剖线分布特征

以林窗北缘为中心,研究了西双版纳地区橡胶林林窗及周边Ｎ－Ｓ样带上光照水平梯度分布。结果表明：林窗的发生导致光照明显增加,从林内到林窗中央,光强呈明显增大趋势,上午雾末消退时,相对光照强度水平梯度变化曲线峰值出现于林窗中央,午后雾消退后,林窗边缘为相对光强梯度变化最甚的地段,峰值由林窗中央向林窗北缘移进。林窗边缘,林窗中央及林内光照强度日变化曲线均为不对称的单峰型,但峰值出现和振幅不同。在太阳高度角