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The fundamental properties of valleys are recently attracting growing attention due to electrons in new and topical materials possessing this degree-of-freedom and recent proposals for valleytronics devices. In silicon MOSFETs, the interest has a longer history since the valley degree of freedom had been identified as a key parameter in the observation of the controversial "metallic behaviour" in two dimensions. However, while it has been recently demonstrated that lifting valley degeneracy can destroy the metallic behaviour, little is known about the role of intervalley scattering. Here, we show that the metallic behaviour can be observed in the presence of strong intervalley scattering in silicon on insulator (SOI) quantum wells. Analysis of the conductivity in terms of quantum corrections reveals that interactions are much stronger in SOI than in conventional MOSFETs, leading to the metallic behaviour despite the strong intervalley scattering. [ABSTRACT FROM AUTHOR]

Abstract.

Rat stomach carcinomas induced by N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) are widely used as a model for differentiated-type human stomach carcinomas. Here, we analyzed expression profiles in five MNNG-induced rat stomach carcinomas by the high-density oligonucleotide microarray containing ∼8000 probe sets. 244 and 208 genes were up- and down-regulated, respectively, by 3-fold and over in four or five carcinomas. Up-regulated genes included those involved in the extracellular matrix remodeling (i.e. Collagen types I, III, V, MMP3), immune response (i.e. lysozyme, complements) and in ossification (i.e. Osteoblast-specific factor). Genes down-regulated included those related to hydrocarbon metabolism (i.e. aldose A, aldehyde dehydrogenase), gastric juice (ion transporter genes) and mucous production (Mucin 5) and gastric hormones (gastrin and somatostatin). The expression profile of the MNNG-induced rat stomach carcinomas shared many features with human stomach carcinomas while cyclin D1 was down-regulated in rat stomach carcinomas but up-regulated in human stomach carcinomas. When the expression profile of the MNNG-induced rat stomach carcinomas was compared with those of two kinds of rat mammary carcinomas, only 13 genes were commonly altered. These results showed that MNNG-induced stomach carcinomas possessed infiltrating capacity and had lost differentiated phenotypes of the stomach, in the same way as human stomach carcinomas, and could be used as a good model for them from the viewpoint of molecular expression profile. [ABSTRACT FROM AUTHOR]

In GaAs quantum Hall (QH) systems, electrons are coupled with nuclear spins through the hyperfine interaction, which is normally not strong enough to change the dynamics of electrons and nuclear spins. The dynamics of the QH systems, however, may drastically change when the nuclear spins interact with low-energy collective excitation modes of the electron spins. We theoretically investigate the nuclear-electron spin interaction in the QH systems as hybrid quantum systems driven by the hyperfine interaction. In particular, we study the interaction between the nuclear spins and the Nambu–Goldstone (NG) mode with the linear dispersion relation associated with the U(1) spin rotational symmetry breaking. We show that such an interaction is described as nuclear spins collectively coupled to the NG mode, and can be effectively described by the Dicke model. Based on the model we suggest that various collective spin phenomena realized in quantum optical systems can also emerge in the QH systems. [ABSTRACT FROM AUTHOR]

Recently piglets have been produced from morulae and early blastocysts vitrified by using methods such as open pulled straw and microdroplet. However, a problem of pollution, such as contamination of embryos with pathological microorganisms from the liquid nitrogen (LN), to the embryos is possible, because embryos must be exposed directly to LN in these methods. Therefore, we designed a new device in which the embryo is vitrified on the stainless steel chip inserted into a 0.25-mL straw without direct contact with LN. To serve as a stainless steel chip, a part of the body of a 19 G needle was cut to reveal its inner surface as the loading site for embryos, and 2 to 15 embryos in a small amount of a vitrification solution were placed on the inner surface of the needle. Then the needle with the embryos was inserted into the 0.25-mL straw which was pre-cooled in LN. This study was conducted to determine the efficiency of vitrification using the new device for porcine embryos at early developmental stages. In Experiment 1, embryos at the compact morula to early blastocyst stages were collected from 7 gilts. The embryos were equilibrated in 20 mM HEPES-buffered PZM (Yoshioka et al. 2003 Biol. Reprod. 69, 2092–2099) (H-PZM) supplemented with 1.8 M ethylene glycol (EG), and then in 1.8 M EG, 0.3 M sucrose, and 2% (w/v) bovine serum albumin (BSA) for 5 min. After equilibration, the embryos were vitrified using H-PZM supplemented with 0.6 M sucrose, 2% (w/v) BSA, and 4 M, 5 M, 6 M, or 7 M EG (ESB). The vitrified embryos were thawed, diluted by directly plunging the needle of the device into H-PZM supplemented with 1.8 M EG and 0.6 M sucrose for 5 min at 38C, and subsequently cultured in PZM supplemented with 10% fetal bovine serum for 48 h; fresh embryos were cultured as a control group. In Experiment 2, embryos were vitrified using 5 M EG ESB, and then 56 vitrified embryos (collected from 4 gilts) were transferred to 4 recipient gilts (12 to 15 embryos per recipient). In Experiment 1, the survival rates of vitrified embryos after 48 h of culture in 4 M, 5 M, 6 M, 7 M, and control groups were 72.7, 86.4, 90.0, 87.0, and 100% (n = 20 to 23), respectively. The 4 M group showed a significantly lower survival rate than the control group (P < 0.05; chi-square test). The expanding and hatching rates of the vitrified embryos in these groups after 48 h of culture were 68.2, 77.3, 70.0, 65.2, and 95.0%, respectively. The 7 M group had a significantly lower expanding and hatching rate than the control group (P < 0.05). In Experiment 2, 3 recipients showed estrus at 19, 29, and 44 days after their previous estrus. One recipient became pregnant and 6 normal live piglets were born. These results indicated that porcine embryos at the compact morula to early blastocyst stages can survive after vitrification using our new device, which can prevent embryos from direct exposure to LN, and that piglets can be obtained from vitrified embryos without fear of pollution from LN. [ABSTRACT FROM AUTHOR]

Objective. Auto-antibodies to signal recognition particle (SRP) are known to be specific to PM among rheumatic disorders, but the specificity in myopathic diseases remains unclear. The clinical utility of anti-SRP antibody in the differential diagnosis of myopathies has not been studied. The aim of the present study was to elucidate whether detection of anti-SRP antibody can discriminate of PM from muscular dystrophy (MD). Methods. We report a patient with a childhood onset myopathy, in whom it was clinically difficult to make a differential diagnosis of PM or MD for 21 yrs, despite repeated muscle biopsies. Myositis-specific auto-antibodies to RNA-associated antigens were screened in this particular case as well as in 105 serum samples from various types of MD and 84 from PM patients using RNA immunoprecipitation. The MD and PM serum samples were obtained from different institutions. The presence of anti-SRP antibody was confirmed by RNA immunoprecipitation combined with immunodepletion of SRP from the antigen. Results. Anti-SRP antibody was positive in the present patient, supporting the diagnosis of PM. Anti-SRP antibody was detected in seven (8.3%) patients with PM, but in none of the patients with MD. Myositis-specific auto-antibodies were not detected in any of the patients with MD. Conclusion. Anti-SRP antibody is useful for discriminating PM from MD among patients with myopathies. [ABSTRACT FROM AUTHOR]