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Objectives: Physiological and behavioral circadian rhythmicities are exhibited by all mammals and are generated by intracellular levels of circadian oscillators, which are composed of transcriptional/translational feedback loops involving a set of circadianclock genes, such as Clock, Per1-3, Cry1-2, Bmal1, Dbp, E4BP4 and CK1e. These circadian-clock genes play important roles in regulating circadian rhythms and also energy homeostasis and metabolism. Determining whether obesity induced by high-fat diet affected the expressions of circadian-clock genes and their related genes in peripheral tissues, was the main focus of this study. To address this issue, we fed male C57BL/6 mice a high-fat diet for 11 months to induce obesity, hyperglycemic, hypercholesterolemic and hyperinsulinemic symptoms, and used quantitative real-time reverse transcription-PCR to measure gene expression levels. Results: We found that the expressions of circadian-clock genes and circadian clock-controlled genes, including Per1-3, Cry1-2, Bmal1, Dbp, E4BP4, CK1e, PEPCK, PDK4 and NHE3, were altered in the livers and/or kidneys. Conclusions: These results indicate that obesity induced by high-fat diet alters the circadian-clock system, and obesity and metabolic syndrome are highly correlated with the expressions of circadian-clock genes and their downstream, circadian clockcontrolled genes.

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We find that Ni L2 edge x-ray magnetic linear dichroism is fully reversed for NiO(001) films on materials with reversed lattice mismatch. We relate this phenomenon to a preferential stabilization of magnetic S domains with main spin component either in or out of the plane, via dipolar interactions. This suggests a way to selectively control spin structures in 3d systems with small spin-orbit coupling.

Based on measurements of soft x-ray magnetic scattering and symmetry considerations, we demonstrate that the magnetoelectric effect in TbMn2O5 arises from an internal field determined by S q × S − q with S q being the magnetization at modulation vector q, whereas the magneto-elastic effect in the exchange energy governs the response to external electric fields. Our results set fundamental symmetry constraints on the microscopic mechanism of multiferroicity in frustrated magnets. PACS numbers: 75.25.+z, 78.70.Ck Materials which exhibit coexistence of magnetism and ferroelectricity with cross coupling, termed multiferroicity, are attractive because they offer the possibility for realizing mutual control of electric and magnetic properties. The key phenomenon behind such mutual control lies on the capability for the induction of magnetization by an electric field or of electric polarization by a magnetic field, known as the magnetoelectric (ME) effect [1,2]. The ME effect is an important characterization of multiferroicity but has been poorly understood. The effect could be largely enhanced by the presence of internal fields. However, such enhancement requires the coexistence and strong coupling of magnetism and ferroelectricity (FE), which rarely happen in real materials. Recent discoveries of giant magnetoelectric couplings in frustrated magnets [3,4] thus offer new opportunities for a thorough scientific understanding of multiferroicity as well as multiferroic applications.In frustrated magnets, such as RMnO 3 and RMn 2 O 5 (R = Tb, Dy, and Ho) [3,4,5,6,7,8,9,10,11,12,13], the spontaneous electric polarization ( P ) appears in certain antiferromagnetic (AF) phases. Unlike old examples of multiferroics, the magnetoelectric couplings exhibited by these materials are gigantic, and the magnetic phases involved are complicated and commonly incommensurate with lattice. The magnetic transition temperature is higher than the ferroelectric one, suggesting that the ferroelectricity is induced by magnetic order. Furthermore, the inversion symmetry in the magnetic phases with ferroelectricity is broken [11,12], implying that the magnetic order couples to odd orders of P . In addition, these magnets show anomalies in the temperature dependence of dielectric constant ε. For RMnO 3 , the ferroelectric transition is accompanied by a magnetic transition from incommensurate sinusoidal to spiral AF order [11,12]. Kenzelmann et al. have applied the GinzburgLandau theory to understand the multiferroic behavior [11]. In contrast, although Chapon et al. [13] found that the ferroelectricity in YMn 2 O 5 results from acentric spin-density waves, little is known about the underlying mechanism of multiferroicity in RMn 2 O 5 because of their structural complexity. The exact relation and interplay between AF order and ferroelectricity in frustrated magnets are unknown and remain controversial [12,13,14,15,16].The presence of internal fields is the simplest origin of the cross coupling between magnetism and ferroelectricity. Microscopica...