Raman scattering through surfaces having biaxial symmetry

Magnetic Raman scattering in two-leg spin ladder materials and the relationship between the anisotropic exchange integrals are analyzed by P. J. Freitas and R. R. P. Singh in Phys. Rev. B, {\bf 62}, 14113 (2000). The angular dependence of the two-magnon scattering is shown to provide information for the magnetic anisotropy in the Sr_14Cu_24O_41 and La_6Ca_8Cu_24O_41 compounds. We point out that the experimental results of polarized Raman measurements at arbitrary angles with respect to the crystal axes have to be corrected for the light ellipticity induced inside the optically anisotropic crystals. We refer quantitatively to the case of Sr_14Cu_24O_41 and discuss potential implications for spectroscopic studies in other materials with strong anisotropy.Comment: To be published as a Comment in Phys. Rev.

A model of gravitation with global U(1)-symmetry

It is shown that an embedding of the general relativity $4-$space into a flat $12-$space gives a model of gravitation with the global $U(1)-$symmetry and the discrete $D_{1}-$one. The last one may be transformed into the $SU(2)-$symmetry of the unified model, and the demand of independence of $U(1)-$ and $SU(2)-$transformations leads to the estimate $\sin^{2}\theta_{min}=0,20$ where $\theta_{min}$ is an analog of the Weinberg angle of the standard model.Comment: 7 page

2D Fractional Supersymmetry for Rational Conformal Field Theory. Application for Third-Integer Spin States

A 2D- fractional supersymmetry theory is algebraically constructed. The Lagrangian is derived using an adapted superspace including, in addition to a scalar field, two fields with spins 1/3,2/3. This theory turns out to be a rational conformal field theory. The symmetry of this model goes beyond the super Virasoro algebra and connects these third-integer spin states. Besides the stress-momentum tensor, we obtain a supercurrent of spin 4/3. Cubic relations are involved in order to close the algebra; the basic algebra is no longer a Lie or a super-Lie algebra. The central charge of this model is found to be 5/3. Finally, we analyse the form that a local invariant action should take.Comment: LaTex, 20 pages. Revised in response to referees' Comment

Physical Acoustics

Contains reports on two research projects.U. S. Navy (Office of Naval Research) under Contract Nonr-1841(42)National Aeronautics and Space Administratio

Organic farming to preserve water quality?Comparison of three emblematic cases of successful management of drinking water catchment area

Protecting water resources from pollutants generated by agricultural activities is becoming more strictly regulated in Europe today, with an obligation to achieveresults. This means that towns willing to improve quality of their domestic water supply are required to regulate farmers’ practices in the water catchment areas. In this paper, we studied three cases (Munich and Augsburg in Germany, and Lons-le-Saunier in France) often listed as successful initiatives/ experiences of preservation of water quality by local authorities that have developed coordination with farmers. In this paper, we carried out a comparative analysis of the construction of city-farmer agreements, based on in-depth surveys and with a particular focus on the role of conversion to organic farming in these agreements. We highlighted several significant differences between these three case studies, with regard to the delimitation of the city’s field of action, the nature of compensation proposed to the farmers, the direct involvement of the city council in the acquisition of land in the vulnerable zone, and the importance granted to organic farming. However, in all three cases we also found similarities, such as the importance, for successful city-farmer coordination, of a facilitator as an intermediary between the two parties, as well as dialogue and contracts that span sufficiently long periods. When these conditions are met, which is the case in the two German cities, the results on the water quality are positive. From this point of view, the German water utilities’ status as “private companies owned by the city” seems to be highly conducive to the introduction of truly environment-friendly practices by farmers. In contrast, in the French case, the greater weight of regulatory constraints on the establishment of direct relations with farmers tends to prevent any fluidity in modes of action and to trigger tensions. Finally, the specific study of the role of conversion to organic farming in the solutions proposed and accepted by the farmers highlights a number of factors needed for the territorial development of this typeof farming: a strong political will that translates into high financial incentives, guaranteed local markets for organic products, and necessary technical support. These factors nevertheless remain insufficient in two of the three case studies, and only the city of Munich, starting off with a particularly favourable situation, has been able to achieve a territorial development of organic farming in tandem with the preservation of its water resources

Dobiński relations and ordering of boson operators

We introduce a generalization of the Dobiński relation, through which we define a family of Bell-type numbers and polynomials. Such generalized Dobiński relations are coherent state matrix elements of expressions involving boson ladder operators. This may be used in order to obtain normally ordered forms of polynomials in creation and annihilation operators, both if the latter satisfy canonical and deformed commutation relations

Goldstone-Mode Phonon Dynamics in the Pyrochlore Cd2Re2O7

We have measured the polarized Raman scattering spectra of Cd2Re2O7, the first superconducting pyrochlore, as a function of temperature. For temperatures below the cubic-to-tetragonal structural phase transition (SPT) at 200K, a peak with B1 symmetry develops at zero frequency with divergent intensity. We identify this peak as the first observation of the Goldstone phonon in a crystalline solid. The Goldstone phonon is a collective excitation that exists due to the breaking of the continuous symmetry with the SPT. Its emergence coincides with that of a Raman-active soft mode. The order parameter for both features derives from an unstable doubly-degenerate vibration (with Eu symmetry) of the O1 atoms which drives the SPT.Comment: 4+ pages, 4 figures. Updated figures and text. Accepted to PR

Efficiency of the lausanne clinical pathway for proximal femoral fractures.

Purpose/Introduction: The number of hip fractures is rising, due to increases in life expectancy. In such cases, patients are at risk from post-operative complications and subsequently the average length of hospitalization may be extended. In 2011, we established a clinical pathway (CP), a specific model of care for patient-care management, to improve the clinical and economic outcomes of proximal femoral fracture management in elderly patients. The goal was to evaluate the CP using clinical, process, and financial indicators. METHODS: We included all surgical patients aged 65 and over, admitted to the emergency department with a fracture of the proximal femur following a fall. Assessment parameters included three performance indicators: clinical, process, and financial. The clinical indicators were the presence or absence of acute delirium on the third post-operative day, diagnosis of nosocomial pneumonia, and the number of patients fulfilling at least 75% of their nutritional requirements at the end of the hospitalization period. The process indicator was the time interval between arrival at the emergency department and surgery. The financial indicator was based on the number of days spent in hospital. RESULTS: From 2011 to 2013, 669 patients were included in the CP. We observed that the average length of stay in hospital decreased as soon as the CP was implemented and stabilized afterwards. The goal of 90% of patients undergoing surgery within 48 h of arrival in the emergency department was surpassed in 2013 (93.1%). Furthermore, we observed an improvement in the clinical indicators. CONCLUSION: The application of a CP allowed an improvement in the qualitative and quantitative efficiency of proximal femoral fracture management in elderly patients, in terms of clinical, process, and financial factors