829 research outputs found
Widely Extended [OIII] 88 um Line Emission around the 30 Doradus Region Revealed with AKARI FIS-FTS
We present the distribution map of the far-infrared [OIII] 88um line emission
around the 30 Doradus (30 Dor) region in the Large Magellanic Cloud obtained
with the Fourier Transform Spectrometer of the Far-Infrared Surveyor onboard
AKARI. The map reveals that the [OIII] emission is widely distributed by more
than 10' around the super star cluster R136, implying that the 30 Dor region is
affluent with interstellar radiation field hard enough to ionize O^{2+}. The
observed [OIII] line intensities are as high as (1-2) x 10^{-6} W m^{-2}
sr^{-1} on the peripheral regions 4'-5' away from the center of 30 Dor, which
requires gas densities of 60-100 cm^{-3}. However the observed size of the
distribution of the [OIII] emission is too large to be explained by massive
stars in the 30 Dor region enshrouded by clouds with the constant gas density
of 10^2 cm^{-3}. Therefore the surrounding structure is likely to be highly
clumpy. We also find a global correlation between the [OIII] and the
far-infrared continuum emission, suggesting that the gas and dust are well
mixed in the highly-ionized region where the dust survives in clumpy dense
clouds shielded from the energetic photons.Comment: 17 pages, 9 figures, accepted for publication in Publications of the
Astronomical Society of Japan (PASJ
±Genetic structure of the oak wilt vector beetle Platypus quercivorus: inferences toward the process of damaged area expansion
<p>Abstract</p> <p>Background</p> <p>The ambrosia beetle, <it>Platypus quercivorus</it>, is the vector of oak wilt, one of the most serious forest diseases in Japan. Population genetics approaches have made great progress toward studying the population dynamics of pests, especially for estimating dispersal. Knowledge of the genetic structuring of the beetle populations should reveal their population history. Using five highly polymorphic microsatellite loci, 605 individuals from 14 sampling sites were assessed to infer the ongoing gene flow among populations as well as the processes of expansion of damaged areas.</p> <p>Results</p> <p>Population differentiation (<it>F</it><sub>ST </sub>= 0.047, <it>G'</it><sub>ST </sub>= 0.167) was moderate and two major clusters were detected by several methods, dividing the samples into north-eastern and south-western populations, a similar genetic divergence was reported in host oak trees. Within the north-eastern populations, the subgroups mostly corresponded to differences in the collection period. The genetic characteristics of the population might have changed after 2 years due to the mixing of individuals between populations with enhanced migration related to population outbreaks. Because isolation by distance was detected for whole populations and also within the north-eastern populations, migration was considered to be limited between neighbouring populations, and most populations were suggested to be in genetic equilibrium of genetic drift and gene flow. Recent bottlenecks were found in some populations with no geographical bias; however, they were all from newly emerged oak wilt forests. The emergence of oak wilt should have induced intense fluctuations in the beetle population size.</p> <p>Conclusions</p> <p>Because the genetic boundaries coincide, we suggest that the geographical structuring of the beetle was formed by co-evolution with the host species. Our findings indicate the oak wilt expansion process.</p
Neuroethology of the Waggle Dance: How Followers Interact with the Waggle Dancer and Detect Spatial Information
Since the honeybee possesses eusociality, advanced learning, memory ability, and information sharing through the use of various pheromones and sophisticated symbol communication (i.e., the "waggle dance"), this remarkable social animal has been one of the model symbolic animals for biological studies, animal ecology, ethology, and neuroethology. Karl von Frisch discovered the meanings of the waggle dance and called the communication a "dance language." Subsequent to this discovery, it has been extensively studied how effectively recruits translate the code in the dance to reach the advertised destination and how the waggle dance information conflicts with the information based on their own foraging experience. The dance followers, mostly foragers, detect and interact with the waggle dancer, and are finally recruited to the food source. In this review, we summarize the current state of knowledge on the neural processing underlying this fascinating behavior
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