226 research outputs found

    Mean-field Study of Charge, Spin, and Orbital Orderings in Triangular-lattice Compounds ANiO2 (A=Na, Li, Ag)

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    We present our theoretical results on the ground states in layered triangular-lattice compounds ANiO2 (A=Na, Li, Ag). To describe the interplay between charge, spin, orbital, and lattice degrees of freedom in these materials, we study a doubly-degenerate Hubbard model with electron-phonon couplings by the Hartree-Fock approximation combined with the adiabatic approximation. In a weakly-correlated region, we find a metallic state accompanied by \sqroot3x\sqroot3 charge ordering. On the other hand, we obtain an insulating phase with spin-ferro and orbital-ferro ordering in a wide range from intermediate to strong correlation. These phases share many characteristics with the low-temperature states of AgNiO2 and NaNiO2, respectively. The charge-ordered metallic phase is stabilized by a compromise between Coulomb repulsions and effective attractive interactions originating from the breathing-type electronphonon coupling as well as the Hund's-rule coupling. The spin-orbital-ordered insulating phase is stabilized by the cooperative effect of electron correlations and the Jahn-Teller coupling, while the Hund's-rule coupling also plays a role in the competition with other orbital-ordered phases. The results suggest a unified way of understanding a variety of low-temperature phases in ANiO2. We also discuss a keen competition among different spin-orbital-ordered phases in relation to a puzzling behavior observed in LiNiO2

    Unique Phase Transition on Spin-2 Triangular Lattice of Ag2MnO2

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    Ag2MnO2 is studied as a possible candidate compound for an antiferromagnetic XY spin model on a triangular lattice. In spite of the large Curie-Weiss temperature of -430 K found in magnetic susceptibi-lity, Mn3+ spins with S = 2 do not undergo a conventional long-range order down to 2 K probably owing to the geometrical frustration and two dimensionality in the system. Instead, a unique phase transition is found at 80 K, where specific heat exhibits a clear sign of a second-order phase transition, while magnetic susceptibility changes smoothly without a distinct anomaly. We think that this transition is related to the chirality degree of freedom associated with a short-range order, which has been expected for the classical XY spin model on a triangular lattice. On further cooling, spin-glass-like behavior is observed below 22 K, possibly corresponding to a quasi-long-range order.Comment: to appear in J. Phys. Soc. Jpn, Vol. 77, No.

    Making sense of joint commissioning: three discourses of prevention, empowerment and efficiency

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    Background: In recent years joint commissioning has assumed an important place in the policy and practice of English health and social care. Yet, despite much being claimed for this way of working there is a lack of evidence to demonstrate the outcomes of joint commissioning. This paper examines the types of impacts that have been claimed for joint commissioning within the literature. Method: The paper reviews the extant literature concerning joint commissioning employing an interpretive schema to examine the different meanings afforded to this concept. The paper reviews over 100 documents that discuss joint commissioning, adopting an interpretive approach which sought to identify a series of discourses, each of which view the processes and outcomes of joint commissioning differently. Results: This paper finds that although much has been written about joint commissioning there is little evidence to link it to changes in outcomes. Much of the evidence base focuses on the processes of joint commissioning and few studies have systematically studied the outcomes of this way of working. Further, there does not appear to be one single definition of joint commissioning and it is used in a variety of different ways across health and social care. The paper identifies three dominant discourses of joint commissioning – prevention, empowerment and efficiency. Each of these offers a different way of seeing joint commissioning and suggests that it should achieve different aims. Conclusions: There is a lack of clarity not only in terms of what joint commissioning has been demonstrated to achieve but even in terms of what it should achieve. Joint commissioning is far from a clear concept with a number of different potential meanings. Although this ambiguity can be helpful in some ways in the sense that it can bring together disparate groups, for example, if joint commissioning is to be delivered at a local level then more specificity may be required in terms of what they are being asked to deliver

    The NHXM observatory

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    Protection Induced by Plasmodium falciparum MSP142 Is Strain-Specific, Antigen and Adjuvant Dependent, and Correlates with Antibody Responses

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    Vaccination with Plasmodium falciparum MSP142/complete Freund's adjuvant (FA) followed by MSP142/incomplete FA is the only known regimen that protects Aotus nancymaae monkeys against infection by erythrocytic stage malaria parasites. The role of adjuvant is not defined; however complete FA cannot be used in humans. In rodent models, immunity is strain-specific. We vaccinated Aotus monkeys with the FVO or 3D7 alleles of MSP142 expressed in Escherichia coli or with the FVO allele expressed in baculovirus (bv) combined with complete and incomplete FA, Montanide ISA-720 (ISA-720) or AS02A. Challenge with FVO strain P. falciparum showed that suppression of cumulative day 11 parasitemia was strain-specific and could be induced by E. coli expressed MSP142 in combination with FA or ISA-720 but not with AS02A. The coli42-FVO antigen induced a stronger protective effect than the bv42-FVO antigen, and FA induced a stronger protective effect than ISA-720. ELISA antibody (Ab) responses at day of challenge (DOC) were strain-specific and correlated inversely with c-day 11 parasitemia (r = −0.843). ELISA Ab levels at DOC meeting a titer of at least 115,000 ELISA Ab units identified the vaccinees not requiring treatment (noTx) with a true positive rate of 83.3% and false positive rate of 14.3 %. Correlation between functional growth inhibitory Ab levels (GIA) and cumulative day 11 parasitemia was weaker (r = −0.511), and was not as predictive for a response of noTx. The lowest false positive rate for GIA was 30% when requiring a true positive rate of 83.3%. These inhibition results along with those showing that antigen/FA combinations induced a stronger protective immunity than antigen/ISA-720 or antigen/AS02 combinations are consistent with protection as ascribed to MSP1-specific cytophilic antibodies. Development of an effective MSP142 vaccine against erythrocytic stage P. falciparum infection will depend not only on antigen quality, but also upon the selection of an optimal adjuvant component

    The solar WIND and suprathermal ion composition investigation on the WIND spacecraft

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    The Solar Wind and Suprathermal Ion Composition Experiment (SMS) on WIND is designed to determine uniquely the elemental, isotopic, and ionic-charge composition of the solar wind, the temperatures and mean speeds of all major solar-wind ions, from H through Fe, at solar wind speeds ranging from 175 kms −1 (protons) to 1280 kms −1 (Fe +8 ), and the composition, charge states as well as the 3-dimensional distribution functions of suprathermal ions, including interstellar pick-up He + , of energies up to 230 keV/e. The experiment consists of three instruments with a common Data Processing Unit. Each of the three instruments uses electrostatic analysis followed by a time-of-flight and, as required, an energy measurement. The observations made by SMS will make valuable contributions to the ISTP objectives by providing information regarding the composition and energy distribution of matter entering the magnetosphere. In addition SMS results will have an impact on many areas of solar and heliospheric physics, in particular providing important and unique information on: (i) conditions and processes in the region of the corona where the solar wind is accelerated; (ii) the location of the source regions of the solar wind in the corona; (iii) coronal heating processes; (iv) the extent and causes of variations in the composition of the solar atmosphere; (v) plasma processes in the solar wind; (vi) the acceleration of particles in the solar wind; and (vii) the physics of the pick-up process of interstellar He as well as lunar particles in the solar wind, and the isotopic composition of interstellar helium.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43776/1/11214_2004_Article_BF00751327.pd

    Metal oxide semiconducting interfacial layers for photovoltaic and photocatalytic applications

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