Structure, magnetism, and magnetocaloric properties of MnFeP1−xSix compounds

MnFeP1-xSix compounds with x=0.10,0.20,0.24,0.28,...,0.80,1 were prepared by high-energy ball milling and solid-state reaction. The structural, magnetic, and magnetocaloric properties are investigated as a function of temperature and magnetic field. X-ray diffraction studies show that the samples in the range from x=0.28 to 0.64 adopt the hexagonal Fe2P-type structure with a small amount of second phase which increases with increasing Si content. The samples with lower Si content show the orthorhombic Co2P-type structure. Magnetic measurements show that the paramagnetic-ferromagnetic transition temperatures range from 214 to 377 K. Of much importance is the fact that these compounds do not contain any toxic components and exhibit excellent magnetocaloric properties

Schwinger-Keldysh Propagators from AdS/CFT Correspondence

We demonstrate how to compute real-time Green's functions for a class of finite temperature field theories from their AdS gravity duals. In particular, we reproduce the two-by-two Schwinger-Keldysh matrix propagator from a gravity calculation. Our methods should work also for computing higher point Lorentzian signature correlators. We elucidate the boundary condition subtleties which hampered previous efforts to build a Lorentzian-signature AdS/CFT correspondence. For two-point correlators, our construction is automatically equivalent to the previously formulated prescription for the retarded propagator.Comment: 16 pages, 1 figure, references added; to appear in JHE

Priorities for Pig Research in Southeast Asia and the Pacific to 2010

Livestock Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Holographic Flavor Transport in Arbitrary Constant Background Fields

We use gauge-gravity duality to compute a new transport coefficient associated with a number Nf of massive N=2 supersymmetric hypermultiplet fields propagating through an N=4 SU(Nc) super-Yang-Mills theory plasma in the limits of large Nc and large 't Hooft coupling, with Nf << Nc. We introduce a baryon number density as well as arbitrary constant electric and magnetic fields, generalizing previous calculations by including a magnetic field with a component parallel to the electric field. We can thus compute all components of the conductivity tensor associated with transport of baryon number charge, including a component never before calculated in gauge-gravity duality. We also compute the contribution that the flavor degrees of freedom make to the stress-energy tensor, which exhibits divergences associated with the rates of energy and momentum loss of the flavor degrees of freedom. We discuss two currents that are free from these divergences, one of which becomes anomalous when the magnetic field has a component parallel to the electric field and hence may be related to recent study of charge transport in the presence of anomalies.Comment: 27 page

Novel store–carry–forward scheme for message dissemination in vehicular ad-hoc networks

To improve traffic safety in intelligent transportation systems, vehicles formed by vehicular ad-hoc networks (VANETs) conventionally disseminate warning messages to their nearby vehicles as soon as a dangerous situation occurs. In this paper, we propose a novel scheme employing a novel story–carry–forward (SCF) mechanism to tackle the network partition and broadcast storm problems, which are two major challenges in VANETs. The experimental result in the Veins simulation framework shows that the proposed SCF scheme significantly mitigates broadcast storms relative to other schemes, and maintains good coverage across various traffic densities

On The Determination Of The Magnetic Entropy Change In Materials With First-order Transitions

An accurate method to determine the magnetic entropy change in materials with hysteretic first-order transitions is presented, which is needed to estimate their potential for applications. We have investigated the effect of the maximal entropy change derived from magnetization measurements performed in different measurement processes. The results show that the isothermal entropy change can be derived from the Maxwell relations even for samples with large thermal hysteresis. In the temperature region with hysteresis, overestimating the entropy change can be avoided by measuring the isothermal magnetization of the sample after it is cooled from the paramagnetic state to the measurement temperature. In this way the so-called peak effect is not observed as shown here for a few compounds. © 2009 Elsevier B.V. All rights reserved.3212135593566Gschneidner, K.A., Pecharsky, V.K., Tsokol, A.O., (2005) Reports on Progress in Physics, 68, pp. 1479-1539Brück, E., (2005) Journal of Physics D-Applied Physics, 38, pp. R381-R391Pecharsky, V.K., Gschneidner, K.A., (1997) Physical Review Letters, 78, pp. 4494-4497Pecharsky, V.K., Gschneidner, K.A., (1997) Journal of Magnetism and Magnetic Materials, 167, pp. L179-L184Tegus, O., Brück, E., Buschow, K.H.J., de Boer, F.R., (2002) Nature, 415, pp. 150-152Wada, H., Tanabe, Y., (2001) Applied Physics Letters, 79, pp. 3302-3304Hu, F.X., Shen, B.G., Sun, J.R., Cheng, Z.H., Rao, G.H., Zhang, X.X., (2001) Applied Physics Letters, 78, pp. 3675-3677Terashita, H., Garbe, J.J., Neumeier, J.J., (2004) Physical Review B, 70, p. 094403Gama, S., Coelho, A.A., de Campos, A., Carvalho, A.M.G., Gandra, F.C.G., von Ranke, P.J., de Oliveira, N.A., (2004) Physical Review Letters, 93, p. 237202de Campos, A., Rocco, D.L., Carvalho, A.M.G., Caron, L., Coelho, A.A., Gama, S., Da Silva, L.M., de Oliveira, N.A., (2006) Nature Materials, 5, pp. 802-804Rocco, D.L., de Campos, A., Carvalho, A.M.G., Caron, L., Coelho, A.A., Gama, S., Gandra, F.C.G., de Oliveira, N.A., (2007) Applied Physics Letters, 90, p. 242507Xu, C., Li, G.D., Wang, L.G., (2006) Journal of Applied Physics, 99, p. 123913Giguere, A., Foldeaki, M., Gopal, B.R., Chahine, R., Bose, T.K., Frydman, A., Barclay, J.A., (1999) Physical Review Letters, 83, pp. 2262-2265Sun, J.R., Hu, F.X., Shen, B.G., (2000) Physical Review Letters, 85, p. 4191Liu, G.J., Sun, R., Shen, J., Gao, B., Zhang, H.W., Hu, F.X., Shen, B.G., (2007) Applied Physics Letter, 90, p. 032507de Oliveira, N.A., von Ranke, P.J., (2008) Physical Review B, 77, p. 214439Tegus, O., Brück, E., Zhang, L., Dagula, Buschow, K.H.J., de Boer, F.R., (2002) Physica B, 319, pp. 174-192Thanh, D.T.C., Brück, E., Tegus, O., Klaasse, J.C.P., Gortenmulder, T.J., Buschow, K.H.J., (2006) Journal of Applied Physics, 99, pp. 08Q107Hermann, R.P., Tegus, O., Brück, E., Buschow, K.H.J., de Boer, F.R., Long, G.J., Grandjean, F., (2004) Physical Review B, 70, p. 214425Liu, D., Yue, M., Zhang, J., McQueen, T.M., Lynn, J.W., Wang, X., Chen, Y., Huang, Q., (2009) Physical Review B, 79, p. 014435Wada, H., private communicatio