No abstract

The phonon spectrum of hcp He4 has been measured along the three principal symmetry axes by inelastic neutron scattering from a single crystal with a molar volume of 16.00 cm3 at 4. 2 K.The results are in fair agreement with the theoretical calculations of Gillis, Koehler, and Werthamer, the maximum discrepancy heing about 30%. Considerable phonon damping has been observed for the +{LO) and Z&(TO&) branches. A modified axia1ly symmetric forceconstant model has been fitted to the dispersion curves and used as an interpolation scheme to calculate the frequency distribution function and other thermodynamic functions.

The nuclear magnetic resonance and Mossbauer effect of Sn119 have been studied in the cubic intermetallic compounds RSn, (R = La, Ce, Pr, Nd, Sm, and Yb). Both the isotropic and anisotropic components of the Knight shift were determined in the temperature range 77 to 400 OK. In the cases of l'rSn, and NdSn, in which the shift measurements are proportional to the magnetic susceptibility, the results may be understood in terms of the Ruderman-Kittel-Kasuya-Yosida t,heory, with an exchange interaction, I' ; = -0.2 eV. The cases of CeSn, and SmSn, do not appear to be interpretable in terms of the RKKY theory. For PrSn,, NdSn,, and SmSn, the Miissbarier effect of the Sn119 yielded a resolved quadrupole splitting of approximately 1.1 mm/s, independent of temperature in the range 4.2 to 300 OK. The isomer shift was + 0.70 mm/s, relative t o Mg,Gn, also independent of temperature. The measured quadrupole coupling has been compared with that expected on the basis of the ionic model. No magnetic splitting was ever unambiguously observed, even a t 1.5 OK. Assuming that the magnetic splitting remains masked by the quadrupole interaction leads t o an estimate of H,ff 5 9 x lo3 Oe in PrSn, and NdSn,.Kernresonanzuntemochungen und Untersuchungen des MoDbauereffekts an Sn119 wurden in kubischen, intcrmetallischen Verbindungen RSn, (11 = La, Ce, Pr, Nd, Sm und Yb) untersucht. Es werden sowohl dcr isotrope als auch der anisotrope Anteil des Knight Shift im Temperaturbereich 77 bis 400 O K untersucht. Fur PrSn, und NdSn,, in denen die Verschiebung proportional ziir magnetischen Suszeptibilitat ist, konnen die Ergebnisse im Rahmen der Itudermann-Kittel-Kasuya-Yosida-Theorie verstanden werden, wobei als Bustauschwechselwirkung r = -0,2 eV angenommen wird. Die Falle CRSn, und SmSn, scheinen durch die RKKY-Theorie nicht interpretierbar zu sein. FBr l'rSn,. NdSn, und SmSn, ergibt der MoObauereffekt von Sn1l9 eine anfgeloste Quadrupolaufspaltung von ungefahr 1,l mm/s unabhangig von der Teinperatur im .Bereich 4,2 bis 300 OK. Die isomere Verschiebung betragt = 0,70 mm/s, relativ zu Mg,Sn. ebenfalls unabhangig von der Temperatur. Die gemessene Quadrupolkopplung wird mit der a u s dem Ionenmodell erwarteten verglichen. Magnetische Aufspaltung wurde unzweideutig nicht beobachtet, sogar nicht bei 1,5 OK. Unter der Annahme, da13 dic Magnetaufspalt,ung diirch Quadrupolwechselwirkung vcrdeckt bleibt, wird Heff 5 9 x lo3 C)e in PrSn, rind NdSn, abgeschstzt. Introduct,ionIt is well known that whenever an atom or ion possessing a permanent magnetic moment (e.g., a rare-earth ion) is immersed in a metallic matrix, an oscillatory unpaired spin density will be induced in the conduction electron distribution, l ) Work was performed in the Ames Laboratory of the Atomic Energy Commission.Contribution No. 1984.

Transfer pricing and intra-firm trade have been somewhat neglected in the agricultural economics literature. As multinational agribusiness firms (MNFs) gain importance as sources of foreign direct investment in developing countries and as players in international agricultural markets, the need for understanding the motives for and consequences of MNF practices also grows. The first part of this review identifies the practices and issues associated with MNF transfer pricing. The second section reviews survey results on the objectives and influences affecting MNF transfer pricing decisions. The final section then summarizes the theoretical development of transfer pricing analysis in the economics literature.