Ionospheric response to the 2009 sudden stratospheric warming over the equatorial, low, and middle latitudes in the South American sector

The present study investigates the ionospheric total electron content (TEC) and F-layer response in the Southern Hemisphere equatorial, low, and middle latitudes due to major sudden stratospheric warming (SSW) event, which took place during January-February 2009 in the Northern Hemisphere. In this study, using 17 ground-based dual frequency GPS stations and two ionosonde stations spanning latitudes from 2.8°N to 53.8°S, longitudes from 36.7°W to 67.8°W over the South American sector, it is observed that the ionosphere was significantly disturbed by the SSW event from the equator to the midlatitudes. During day of year 26 and 27 at 14:00 UT, the TEC was two times larger than that observed during average quiet days. The vertical TEC at all 17 GPS and two ionosonde stations shows significant deviations lasting for several days after the SSW temperature peak. Using one GPS station located at Rio Grande (53.8°S, 67.8°W, midlatitude South America sector), it is reported for the first time that the midlatitude in the Southern Hemisphere was disturbed by the SSW event in the Northern Hemisphere.Fil: Fagundes, P. R.. Universidade do Vale do Paraíba; BrasilFil: Goncharenko, L. P.. Massachusetts Institute of Technology; Estados UnidosFil: De Abreu, A. J.. Universidade do Vale do Paraíba; BrasilFil: Venkatesh, K.. Universidade do Vale do Paraíba; BrasilFil: Pezzopane, M.. Istituto Nazionale Di Geofisica E Vulcanologia; ItaliaFil: De Jesus, R.. Universidade do Vale do Paraíba; BrasilFil: Gende, Mauricio Alfredo. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coster, A. J.. Massachusetts Institute of Technology; Estados UnidosFil: Pillat, V. G.. Universidade do Vale do Paraíba; Brasi

Spiral Chain O4 Form of Dense Oxygen

Oxygen is in many ways a unique element: the only known diatomic molecular magnet and the capability of stabilization of the hitherto unexpected O8 cluster structure in its solid form at high pressure. Molecular dissociations upon compression as one of the fundamental problems were reported for other diatomic solids (e.g., H2, I2, Br2, and N2), but it remains elusive for solid oxygen, making oxygen an intractable system. We here report the theoretical prediction on the dissociation of molecular oxygen into a polymeric spiral chain O4 structure (\theta-O4) by using first-principles calypso method on crystal structure prediction. The \theta-O4 stabilizes above 2 TPa and has been observed as the third high pressure phase of sulfur (S-III). We find that the molecular O8 phase remains extremely stable in a large pressure range of 0.008 - 2 TPa, whose breakdown is driven by the pressure-induced instability of a transverse acoustic phonon mode at zone boundary, leading to the ultimate formation of \theta-O4. Remarkably, stabilization of \theta-O4 turns oxygen from a superconductor into an insulator with a wide band gap (approximately 5.9 eV) originating from the sp3-like hybridized orbitals of oxygen and the localization of valence electrons. (This is a pre-print version of the following article: Li Zhu et al, Spiral chain O4 form of dense oxygen, Proc. Natl. Acad. Sci. U.S.A. (2011), doi: 10.1073/pnas.1119375109, which has been published online at http://www.pnas.org/content/early/2011/12/27/1119375109 .)Comment: 13 apages, 3 figure

Ionospheric response to the 2009 sudden stratospheric warming over the equatorial, low, and middle latitudes in the South American sector

The present study investigates the ionospheric total electron content (TEC) and F-layer response in the Southern Hemisphere equatorial, low, and middle latitudes due to major sudden stratospheric warming (SSW) event, which took place during January-February 2009 in the Northern Hemisphere. In this study, using 17 ground-based dual frequency GPS stations and two ionosonde stations spanning latitudes from 2.8°N to 53.8°S, longitudes from 36.7°W to 67.8°W over the South American sector, it is observed that the ionosphere was significantly disturbed by the SSW event from the equator to the midlatitudes. During day of year 26 and 27 at 14:00 UT, the TEC was two times larger than that observed during average quiet days. The vertical TEC at all 17 GPS and two ionosonde stations shows significant deviations lasting for several days after the SSW temperature peak. Using one GPS station located at Rio Grande (53.8°S, 67.8°W, midlatitude South America sector), it is reported for the first time that the midlatitude in the Southern Hemisphere was disturbed by the SSW event in the Northern Hemisphere.Facultad de Ciencias Astronómicas y Geofísica

Multidirectional sexual dimorphism for the live weight in domestic pigs

In mammals, males are typically larger and heavier than females. In particular, the average weight of wild boar females is about 80% of that of the males. In a vast majority of domestic swine populations (breeds, populations of breeding groups), this value varies from 70 to 91% (the central value of the range of variation of 81%). However, there are three genealogically continuous groups of domestic pigs (Vietnamese Masked breed MY, minisibs and Svetlogorsk mini-pigs) that make exceptions. Their specific feature is the reverse sexual dimorphism in weight – mature females are heavier than males. This phenomenon, not typical of the species Sus scrofa, was the reason for the present study. Although this research is preliminary, some assumptions can be made. Firstly, the ratio of the weight of mature females to the weight of mature males is obviously characteristic of the species, deviations from which repressed stabilizing selection. Second, in domestic pigs, normal and reverse sexual dimorphism in weight may be different in nature: in the former case, it is a great length of the period of intensive growth in males, in the latter, a large growth rate of females during the first year of life. The third characteristic of domestic pigs in Southeast Asia, early puberty, may be due to a consistent use of young and therefore small-sized males for reproduction purposes; however, the small size due to their youth, cannot be a target of artificial selection – nor can they be the cause of reverse sexual dimorphism in weight. Finally, reverse sexual dimorphism may be due to a tendency towards early obesity in females, which might be to a single mutation as its genetic cause

On micro-structural effects in dielectric mixtures

The paper presents numerical simulations performed on dielectric properties of two-dimensional binary composites on eleven regular space filling tessellations. First, significant contributions of different parameters, which play an important role in the electrical properties of the composite, are introduced both for designing and analyzing material mixtures. Later, influence of structural differences and intrinsic electrical properties of constituents on the composite's over all electrical properties are investigated. The structural differences are resolved by the spectral density representation approach. The numerical technique, without any {\em a-priori} assumptions, for extracting the spectral density function is also presented.Comment: 24 pages, 8 figure and 7 tables. It is submitted to IEEE Transactions on Dielectrics and Electrical Insulatio

Quasi-molecular and atomic phases of dense solid hydrogen

The high-pressure phases of solid hydrogen are of fundamental interest and relevant to the interior of giant planets; however, knowledge of these phases is far from complete. Particle swarm optimization (PSO) techniques were applied to a structural search, yielding hitherto unexpected high-pressure phases of solid hydrogen at pressures up to 5 TPa. An exotic quasi-molecular mC24 structure (space group C2/c, stable at 0.47-0.59 TPa) with two types of intramolecular bonds was predicted, providing a deeper understanding of molecular dissociation in solid hydrogen, which has been a mystery for decades. We further predicted the existence of two atomic phases: (i) the oC12 structure (space group Cmcm, stable at > 2.1 TPa), consisting of planar H3 clusters, and (ii) the cI16 structure, previously observed in lithium and sodium, stable above 3.5 TPa upon consideration of the zero-point energy. This work clearly revised the known zero-temperature and high-pressure (>0.47 TPa) phase diagram for solid hydrogen and has implications for the constituent structures of giant planets.Comment: accepted in The Journal of Physical Chemistr

Polymorphic loci of coat color in mini-pigs

The present work is phenomenological and purely descriptive. It shows polymorphism of colors in a breeding group of mini-pig in the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences (ICG SB RAS) and makes some assumptions about the nature of this genetic diversity. In the ICG SB RAS mini-pig herd, wild-type coloration (agouti), black-spots, black and white color are present. All these options have variants, including previously undescribed, with genetically determined differences. In addition, the ICG SB RAS mini-pigs have variants inherent only to heterozygous individuals and archaic gray color described only in primitive domestic pig. Comparison of the observed color phenotypes in the breeding with literature data showed that EDNRB, KIT, KITLG and the MC1R are polymorphic loci, while ASIP, OCA2 and TYRP1 are monomorphic loci. Thus, the loci that control the most common coat colors in domestic pigs are polymorphic, while those controlling rare or relatively rare colors and monomorphic. The research allowed us to put forward some assumptions concerning the genetic determination of the phenotypic characteristics of color seen in the study group selection. Among these assumptions is one about the genetic control of juvenile colors in domestic pigs. Observations made in the ICG SB RAS mini-pig breeding group allowed us to examine and describe the features of age-related changes of an embodiment of black-motley suit, when newborn piglets originally have black-and-motley fur color on the brick-red background and at an age of one year, a gray roan background formed by a mixture of white and black hairs. In addition, it was shown that with the help of technical means black spots can also be detected on a black background

Juvenile coat colours in mini-pigs at ICG

This article continues a previous study colors in minipigs at ICG. It also has a phenomenological character, but it consideres juvenile colour, which is an integral element of the ontogenetic formation of the suit, wild type agouti pigs of the species Sus scrofa L. However, in ICG mini pigs, in addition to individuals with the suit of the wild type, juvenile colour is a feature of pigs with the black spotted suit. It should be noted that data about a similar phenomenon in pigs with black spotted colour were not found in the literature. We proposed that a unique juvenile colour of black spotted mini-pigs ICG is a consequence of increased synthesis of pigments of hair, the intensity of which obviously exceeds the performance by the wild boar and domestic pigs. Newborn piglets of mini pigs ICG of the colour of the wild type typically have too little or too much yellow (orange, brown) pigment, which makes the figure of juvenile livery blurry – low contrast, or the lack of it, with the result that they are gray or gray-blue color with dark gray longitudinal stripes. The pattern of juvenile livery piglets of mini pigs ICG is disrupted. As a rule, instead of a longitudinal stripe, a mesh pattern livery is observed. Therefore, the agouti like colour observed in mini-pigs ICG should rather be called more properly pseudowild type. It was suggested that the specially planned crosses were able to “reveal” the genetic load of mutations in the complex of alleles involved in the formation of the suit of the wild type and accumulated in the population, not exposed to stabilizing selection on this archaic for domestic pigs’ colour. The accumulation of this genetic cargo at the mini-pigs was made possible by gipostatic suit wild type relative to epistatic colour standard for modern commercial plant breeds

Matter-Wave Solitons in an F=1 Spinor Bose-Einstein Condensate

Following our previous work [J. Ieda, T. Miyakawa, M. Wadati, cond-mat/0404569] on a novel integrable model describing soliton dynamics of an F=1 spinor Bose--Einstein condensate, we discuss in detail the properties of the multi-component system with spin-exchange interactions. The exact multiple bright soliton solutions are obtained for the system where the mean-field interaction is attractive (c_0 < 0) and the spin-exchange interaction is ferromagnetic (c_2 < 0). A complete classification of the one-soliton solution with respect to the spin states and an explicit formula of the two-soliton solution are presented. For solitons in polar state, there exists a variety of different shaped solutions including twin peaks. We show that a "singlet pair" density can be used to distinguish those energetically degenerate solitons. We also analyze collisional effects between solitons in the same or different spin state(s) by computing the asymptotic forms of their initial and final states. The result reveals that it is possible to manipulate the spin dynamics by controlling the parameters of colliding solitons.Comment: 12 pages, 9 figures, to appear in J. Phys. Soc. Jpn. Vol.73 No.11 (2004