We report the appearance of magnetization jumps in the magnetic hysteresis curves of the spinel oxide FeV2O4, in which two different magnetic transition ions appeared, both of them having orbital degrees of freedom. The spin-glass-like transition was observed from ac magnetic susceptibilities and the transition temperature was estimated to be Tg=85.5 K. The magnetization jumps appear below 90 K at B=0. In addition, jumps at B=±1.2 T appear below 4.6 K. The magnetization jumps at B=0 may be correlated with spin-glass-like behaviors.

A B S T R A C TThe abundance, sex ratio, growth, sexual maturity, morphological sex dimorphism, and reproduction of the portunid crab Charybdis bimaculata was studied in Tokyo Bay, Japan, between November 2002 and October 2003. Relative abundance [inferred from catch-perunit-effort (CPUE)] was higher and lower during summer and winter months, respectively. The proportion of males varied between 0.2-0.5 throughout the year and the overall sex ratio was greatly biased toward females. The population had a unimodal size frequency distribution and the life-span was estimated to be about one year. Growth was not depressed in winter and was adequately described by the von Bertalanffy growth equation. The puberty molt in males brought about changes in the relative size of the chelipeds and gonopods and was estimated to occur within a carapace length (CL) range of 12.50-16.00 mm. Puberty in females was evidenced by a sharp increase in the pleon width and was estimated to occur at CLs between 11.34 and 16.74 mm. Morphological sexual dimorphism was observed in all features which showed secondary sexual development (cheliped dimensions, carapace and pleon width, and body weight). Ovarian development was uniformly arrested only during winter but began developing in early spring, and mating (insemination) increased in frequency between spring and summer. Ovigerous females were found in all seasons except for winter, but were more common during the warmer months. Batch fecundity ranged from 8,300 to 38,400 eggs per female and was positively correlated with body size. C. bimaculata displays the typical reproductive features and spawning pattern of temperate portunid crabs in spite of its short life-span.

We investigated neuronal response to repetitive transcranial magnetic stimulation (rTMS) and electroconvulsive shock (ECS) in terms of c-Fos expression. In rats at postnatal day 49, six rTMS sessions induced widespread nuclear c-Fos-like immunoreactivity in frontal cortex, lateral orbital cortex, striatum, lateral septal nucleus, piriform cortex, dentate gyrus, Ammon's horn, cingulate cortex, parietal cortex, thalamus, occipital cortex, and amygdala; this reactivity was greater than with two sessions of rTMS or sham rTMS. ECS produced even stronger c-Fos expression than six sessions of rTMS in all regions except thalamus (no difference) and striatum (stronger with rTMS). Thus, functional modification of neuroanatomic substrates as demonstrated by c-Fos expression may partially differ between rTMS and ECS.

T o determine whether there are metabolite changes in the left medial temporal and frontal lobes with agng, we performed proton magnetic resonance spectroscopy in 36 normal subjects. The N-acetylaspartatel creatine-phosphocreatine ratio in the medial temporal lobe tended to be decreased in subjects over 60 years of age. The ratio decrease in the frontal lobe related to aging was lower than that in the medial temporal lobe. There were no significant differences in the metabolite ratios between males and females. These findings suggest that structures in the medial temporal lobe may be more susceptible to neuronal dysfunction associated with aging than those in the frontal lobe.

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