1,157 research outputs found
Synchronous and Non-Synchronous Semelparity in Sibling Species of Pulmonates
Diverse life histories have been documented in terrestrial pulmonates, which inhabit different regions in climate. Life history traits are often phenotypically plastic and vary depending on the environment. Thus, surveys using designs that control for the confounding effects of environment are needed to evaluate the evolutionary differences between populations of closely related species in the wild. We examined the life histories of sibling species of terrestrial pulmonate within two regions of similar climates. Bradybaena pellucida (BP) is endemic to Japanese islands, and has recently been expanding its distribution northeastward, whereas B. similaris (BS) has been introduced by humans into temperate and tropical regions worldwide. We found that these species exhibit discrete differences in population dynamics and life cycle, despite their close relatedness. The annual life cycle of BP is synchronized among individuals in a population. Thus, BP is univoltine with discontinuous generation. In contrast, BS individuals do not synchronize their growth or reproduction, and thus exhibit overlapping generations. Our results indicate that synchronized and non-synchronized population dynamics diverge relatively rapidly in semelparous pulmonates. This type of difference has not been documented in pulmonate life history, and may have been overlooked because only a few studies have explicitly compared life cycles of closely related species within the same climate. Our results provide a basis for further studies of life history evolution in pulmonates.ArticleZOOLOGICAL SCIENCE. 32(4):372-377 (2015)journal articl
XPS Determination of Compositions of Alloy Surfaces and Surface Oxides on Mechanically Polished Iron-Chromium Alloys(Metallurgy)
Using the XPS technique, the compositions of the alloy surface and the surface oxide on mechanically polished iron-chromium alloys were studied. For quantitative analysis, the ratio of photo-ionization cross section of Fe 2p_ electrons to that of Cr 2p_ electrons was estimated as 1.35 for Al Kα_ radiation. Assuming a homogeneous oxide layer, the thickness of the oxide layer and compositions of the alloy surface and the surface oxide were simultaneously determined. The results showed no enrichment of chromium or iron either in the oxide layer or the alloy surface. Results on binding energies were also given
Theory of ac electrokinetic behavior of spheroidal cell suspensions with an intrinsic dispersion
The dielectric dispersion, dielectrophoretic (DEP) and electrorotational (ER)
spectra of spheroidal biological cell suspensions with an intrinsic dispersion
in the constituent dielectric constants are investigated. By means of the
spectral representation method, we express analytically the characteristic
frequencies and dispersion strengths both for the effective dielectric constant
and the Clausius-Mossotti factor (CMF). We identify four and six characteristic
frequencies for the effective dielectric spectra and CMF respectively, all of
them being dependent on the depolarization factor (or the cell shape). The
analytical results allow us to examine the effects of the cell shape, the
dispersion strength and the intrinsic frequency on the dielectric dispersion,
DEP and ER spectra. Furthermore, we include the local-field effects due to the
mutual interactions between cells in a dense suspension, and study the
dependence of co-field or anti-field dispersion peaks on the volume fractions.Comment: accepted by Phys. Rev.
ESCA Study of the Passive Film on an Extremely Corrosion-Resistant Amorphous Iron Alloy
X-ray photoelectron spectroscopy was applied to study the composition of the passive film formed on an extremely corrosion resistant amorphous Fe-10at.%Cr-13at.%P-7at.%C alloy in 1 N HCl. The passive film consists mainly of hydrated chromium oxyhydroxide which is a common major constituent of passive films on crystalline stainless steels. The extremely high corrosion resistance of the amorphous alloy can only in part be attributed to the formation of a protective hydrated chromium oxyhydroxide film
SuprimeCam Observation of Sporadic Meteors during Perseids 2004
We report the serendipitous findings of 13 faint meteors and 44 artificial
space objects by Subaru SuprimeCam imaging observations during 11-16 August
2004. The meteors, at about 100km altitude, and artificial satellites/debris in
orbit, at 500km altitude or higher, were clearly discriminated by their
apparent defocused image sizes. CCD photometry of the 13 meteors, including 1
Perseid, 1 Aquarid, and 11 sporadic meteors, was performed. We defined a peak
video-rate magnitude by comparing the integrated photon counts from the
brightest portion of the track traversed within 33ms to those from a 0-mag star
during the same time duration. This definition gives magnitudes in the range
4.0< V_{vr} <6.4 and 4.1< I_{vr}<5.9 for these 13 meteors. The corresponding
magnitude for virtual naked-eye observers could be somewhat fainter especially
for the V-band observation, in which the [OI] 5577 line lasting about 1 sec as
an afterglow could contribute to the integrated flux of the present 5-10 min
CCD exposures. Although the spatial resolution is insufficient to resolve the
source size of anything smaller than about 1 m, we developed a new estimate of
the collisionally excited column diameter of these meteors. A diameter as small
as a few mm was derived from their collisionally excited photon rates, meteor
speed, and the volume density of the oxygen atoms at the 100km altitude. The
actual column diameter of the radiating zone, however, could be as large as few
100m because the excited atoms travel that distance before they emit forbidden
lines in 0.7 sec of its average lifetime. Among the 44 artificial space
objects, we confirmed that 17 were cataloged satellites/space debris.Comment: 14 pages, 13 figures, 5 tables, submitted to PAS
Optical to Near-IR Spectrum of a Massive Evolved Galaxy at z = 1.26
We present the optical to near-infrared (IR) spectrum of the galaxy TSPS
J1329-0957, a red and bright member of the class of extremely red objects
(EROs) at z = 1.26. This galaxy was found in the course of the Tokyo-Stromlo
Photometry Survey (TSPS) which we are conducting in the southern sky. The
spectroscopic observations were carried out with the Gemini Multi-Object
Spectrograph (GMOS) and the Gemini Near Infra-Red Spectrograph (GNIRS) mounted
on the Gemini-South telescope. The wide wavelength coverage of 0.6 - 2.3 um
provides useful clues as to the nature of EROs while most published spectra are
limited to a narrower spectral range which is dictated by the need for
efficient redshift determination in a large survey. We compare our spectrum
with several optical composite spectra obtained in recent large surveys, and
with stellar population synthesis models. The effectiveness of using near-IR
broad-band data, instead of the spectral data, in deriving the galaxy
properties are also investigated. We find that TSPS J1329-0957 formed when the
universe was 2 - 3 Gyr old, and subsequently evolved passively to become one of
the most massive galaxies found in the z = 1 - 2 universe. Its early type and
estimated stellar mass of M* = 10^{11.5} Msun clearly point to this galaxy
being a direct ancestor of the brightest elliptical and spheroidal galaxies in
the local universe.Comment: 18 pages, 4 figures. Accepted for publication in Ap
First-Principles Approach to Electrorotation Assay
We have presented a theoretical study of electrorotation assay based on the
spectral representation theory. We consider unshelled and shelled spheroidal
particles as an extension to spherical ones. From the theoretical analysis, we
find that the coating can change the characteristic frequency at which the
maximum rotational angular velocity occurs. The shift in the characteristic
frequency is attributed to a change in the dielectric properties of the
bead-coating complex with respect to those of the uncoated particles. By
adjusting the dielectric properties and the thickness of the coating, it is
possible to obtain good agreement between our theoretical predictions and the
assay data.Comment: 17 pages, 4 eps figures; minor revisions, accepted for publications
by J. Phys.: Condens. Matte
Electrorotation of a pair of spherical particles
We present a theoretical study of electrorotation (ER) of two spherical
particles under the action of a rotating electric field. When the two particles
approach and finally touch, the mutual polarization interaction between the
particles leads to a change in the dipole moment of the individual particle and
hence the ER spectrum, as compared to that of the well-separated particles. The
mutual polarization effects are captured by the method of multiple images. From
the theoretical analysis, we find that the mutual polarization effects can
change the characteristic frequency at which the maximum angular velocity of
electrorotation occurs. The numerical results can be understood in the spectral
representation theory.Comment: Minor revisions; accepted by Phys. Rev.
Left-right asymmetric expression of dpp in the mantle of gastropods correlates with asymmetric shell coiling
This is the final version of the article. Available from BMC via the DOI in this record.BACKGROUND: Various shapes of gastropod shells have evolved ever since the Cambrian. Although theoretical analyses of morphogenesis exist, the molecular basis of shell development remains unclear. We compared expression patterns of the decapentaplegic (dpp) gene in the shell gland and mantle tissues at various developmental stages between coiled-shell and non-coiled-shell gastropods. RESULTS: We analyzed the expression patterns of dpp for the two limpets Patella vulgata and Nipponacmea fuscoviridis, and for the dextral wild-type and sinistral mutant lineage of the pond snail Lymnaea stagnalis. The limpets had symmetric expression patterns of dpp throughout ontogeny, whereas in the pond snail, the results indicated asymmetric and mirror image patterns between the dextral and sinistral lineages. CONCLUSION: We hypothesize that Dpp induces mantle expansion, and the presence of a left/right asymmetric gradient of the Dpp protein causes the formation of a coiled shell. Our results provide a molecular explanation for shell, coiling including new insights into expression patterns in post-embryonic development, which should aid in understanding how various shell shapes are formed and have evolved in the gastropods.This study was supported by the JSPS Grants-in-Aid for Scientific Research 15104009
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