Loading atom lasers by collectivity-enhanced optical pumping

The effect of collectivity on the loading of an atom laser via optical pumping is discussed. In our model, atoms in a beam are laser-excited and subsequently spontaneously decay into a trapping state. We consider the case of sufficiently high particle density in the beam such that the spontaneous emission is modified by the particle interaction. We show that the collective effects lead to a better population of the trapping state over a wide range of system parameters, and that the second order correlation function of the atoms can be controlled by the applied laser field.Comment: 5 pages, 7 figure

The Relationship Between the Sociology of Christian Religion and the Metaphysics of Morality

The objective reality of the moral Christian act is composed of four structural elements of social organization: 1. the individual human subject; 2. its manifestation as a concrete act; 3. the moral rules of the Scripture and 4. the Holy Spirit, the informational energy of Divinity, which binds the first three structural elements into a unitary whole through the mediation of the individual human consciousness.The implementation of the social moral act in the religious experience can be achieved by adopting a paradigmatic model whereby an attempt is made at an empirical match between the practical social aspects of morality and the objective existence of the real social system of humanity, integrated in the structure of the universe as a whole, through the intermediary of the uncreated informational energy of the Holy Spirit

Algorithm Developments for Discrete Adjoint Methods

This paper presents a number of algorithm developments for adjoint methods using the 'discrete' approach in which the discretisation of the non-linear equations is linearised and the resulting matrix is then transposed. With a new iterative procedure for solving the adjoint equations, exact numerical equivalence is maintained between the linear and adjoint discretisations. The incorporation of strong boundary conditions within the discrete approach is discussed, as well as a new application of adjoint methods to linear unsteady flow in turbomachinery

Mandatory multidisciplinary approach for the evaluation of the lymph node status in rectal cancer

Colorectal cancer is the third most frequently reported malignancy and also the third leading cancer-related cause of death worldwide. Lymph node evaluation, both preoperatively and postoperatively, represents an important aspect of the diagnosis and therapeutic strategy in colorectal cancer, such that an accurate preoperative staging is required for a correct therapeutic strategy. Treatment of rectal cancer with positive lymph nodes, a very important predictive prognostic parameter, is currently based on neoadjuvant chemoradiotherapy followed by total/ surgical mesorectal excision and adjuvant regimen. Preoperative evaluation of the lymph node status in rectal cancer is based on endoscopic ultrasound and magnetic resonance imaging, but their accuracy, specificity, and sensitivity still require improvement. Postoperative evaluation also presents points of debate, especially related to the role of sentinel lymph node mapping and their final implication, represented by detection of micrometastases and isolated tumor cells. The pathologic interpretation of tumor deposits represents other points in discussion. From a surgical perspective, extended lateral lymph node dissection vs. abstinence and (neo)adjuvant therapeutic approach represent another unresolved issue. This review presents the major controversies existing today in the treatment and pathologic interpretation of the lymph nodes in rectal cancer, the role/ indication and value of the lateral pelvic lymph node dissection, and the postoperative interpretation of the value of the micrometastatic disease and tumor deposits

Positivity and optimization for semi-algebraic functions

We describe algebraic certificates of positivity for functions belonging to a finitely generated algebra of Borel measurable functions, with particular emphasis to algebras generated by semi-algebraic functions. In which case the standard global optimization problem with constraints given by elements of the same algebra is reduced via a natural change of variables to the better understood case of polynomial optimization. A collection of simple examples and numerical experiments complement the theoretical parts of the article.Comment: 20 page

A micromechanics based constitutive model for fibre reinforced cementitious composites

A new constitutive model for fibre reinforced cementitious composites based on micromechanical solutions is proposed. The model employs a two-phase composite based on the Eshelby matrix-inclusion solution and the Mori-Tanaka homogenization scheme and also simulates directional microcracking. An exterior point Eshelby based criterion is employed to model crack-initiation in the matrix-inclusion interface. Microcrack surfaces are assumed to be rough and able to regain contact under both normal and shear displacements. Fibres are included into the formulation in both cracked and uncracked conditions. Once cracks start to develop, the crack-bridging action of fibres is simulated using a local constitutive equation that accounts for the debonding and pull-out of fibre groups with different orientations. It is shown that the combination of the rough microcrack and fibre-bridging sub-models allows microcracking behaviour deriving from both tensile and compressive loads to be modelled in a unified manner. This ability to model tensile and compressive behaviour using the same micromechanical mechanisms is considered to be a particularly attractive feature of the formulation, which removes the need for multi-parameter triaxial yield surfaces and evolution functions that bedevil many competitor models. The model is successfully validated using a series of examples based on experimental test data

Sound propagation in a solid through a screen of cylindrical scatterers

The propagation of SH waves in a solid containing a screen of line-like scatterers is investigated. When the scatterers are uniformly distributed, the amplitudes of the coherent waves inside and outside the screen are evaluated in closed form. In the analysis, multiple scattering effects are taken into account within the context of a first-order approximation. A Global Closure Assumption is proposed, which yields an effective wavenumber identical to that of Waterman and Truell. The scatterers can be fibers of circular or elliptical cross-sections; they can also be two-dimensional cracks with slit-like or elliptical cross-sections. Specific analytical and numerical results are presented for flat cracks and empty cavities of circular cross-sections. In those two cases, figures are presented to illustrate the variations of the reflection and transmission coefficients as functions of frequency and of scatterer concentration. The crack and cavity results, respectively, are compared with those of earlier works