Cooling slope casting to obtain thixotropic feedstock

Thixoforming, and related semi-solid processing routes for metallic alloys, require feedstock with a non-dendritic microstructure in the semi-solid state. The material then behaves in a thixotropic way in that, when it is sheared it flows and can be forced to fill a die and, when it is allowed to stand it thickens again. The New Rheocasting (the NRC process) is a recently developed semi-solid processing route. There are two versions of this route. In one, molten alloy is poured directly into a tilted mould and, through careful temperature control during cooling, a spheroidal semi-solid microstructure is achieved. The material in the mould is then upended into a shot sleeve and hence forced into a die. Alternatively, the molten alloy is poured onto a cooling slope and thence into a mould before processing. The aim of the work described in this paper was to develop understanding of the microstructural development during the initial stages of this process. The results for pouring A356 aluminium alloy via a cooling slope into a mould are presented

Testing strong gravity with gravitational waves and Love numbers

The LIGO observation of GW150914 has inaugurated the gravitational-wave astronomy era and the possibility of testing gravity in extreme regimes. While distorted black holes are the most convincing sources of gravitational waves, similar signals might be produced also by other compact objects. In particular, we discuss what the gravitational-wave ringdown could tell us about the nature of the emitting object, and how measurements of the tidal Love numbers could help us in understanding the internal structure of compact dark objects

The holographic RG flow in a field theory on a curved background

As shown by Freedman, Gubser, Pilch and Warner, the RG flow in ${\cal N}=4$ super-Yang-Mills theory broken to an ${\cal N}=1$ theory by the addition of a mass term can be described in terms of a supersymmetric domain wall solution in five-dimensional ${\cal N}=8$ gauged supergravity. The FGPW flow is an example of a holographic RG flow in a field theory on a flat background. Here we put the field theory studied by Freedman, Gubser, Pilch and Warner on a curved $AdS_4$ background, and we construct the supersymmetric domain wall solution which describes the RG flow in this field theory. This solution is a curved (non Ricci flat) domain wall solution. This example demonstrates that holographic RG flows in supersymmetric field theories on a curved $AdS_4$ background can be described in terms of curved supersymmetric domain wall solutions.Comment: 14 pages, LaTe

Entanglement versus mixedness for coupled qubits under a phase damping channel

Quantification of entanglement against mixing is given for a system of coupled qubits under a phase damping channel. A family of pure initial joint states is defined, ranging from pure separable states to maximally entangled state. An ordering of entanglement measures is given for well defined initial state amount of entanglement.Comment: 9 pages, 2 figures. Replaced with final published versio

Late-Time Tails of Wave Propagation in Higher Dimensional Spacetimes

We study the late-time tails appearing in the propagation of massless fields (scalar, electromagnetic and gravitational) in the vicinities of a D-dimensional Schwarzschild black hole. We find that at late times the fields always exhibit a power-law falloff, but the power-law is highly sensitive to the dimensionality of the spacetime. Accordingly, for odd D>3 we find that the field behaves as t^[-(2l+D-2)] at late times, where l is the angular index determining the angular dependence of the field. This behavior is entirely due to D being odd, it does not depend on the presence of a black hole in the spacetime. Indeed this tails is already present in the flat space Green's function. On the other hand, for even D>4 the field decays as t^[-(2l+3D-8)], and this time there is no contribution from the flat background. This power-law is entirely due to the presence of the black hole. The D=4 case is special and exhibits, as is well known, the t^[-(2l+3)] behavior. In the extra dimensional scenario for our Universe, our results are strictly correct if the extra dimensions are infinite, but also give a good description of the late time behaviour of any field if the large extra dimensions are large enough.Comment: 6 pages, 3 figures, RevTeX4. Version to appear in Rapid Communications of Physical Review

MANNA FROM HEAVEN: THE EXUBERANCE OF FOOD AS A TOPIC FOR RESEARCH IN MANAGEMENT AND ORGANIZATION

Organizations have, in the past, often been discussed as if they were Cartesian mentalities, planning agendas, learning from doing, processing information, reducing equivocality, mimicking and copying, floating disembodiedly apart from the actors who work in these organizations. We are offered representations of organizations as organically grounded metaphors that minimize the biological facticity of employees: namely, their need for food. While the inputs to organizations conceived as if they were quasi-systems are well explored, and the emotional and ‘irrational’ side of organizations is increasingly explored, the necessity of inputs to the biological systems that staff them is not. Nonetheless, despite the lack of explicit scholarly attention to food at work, its importance guarantees its hidden presence in the organizational literature, often in the context of more “serious” themes. We identify four approaches to the relationship between food, work and organization. For dessert, we propose a research menu that aims to uncover several possibilities for making the role of food in organizational life more explicit.

COPD and cardiovascular disease

COPD is one of the major public health problems in people aged 40 years or above. It is currently the 4th leading cause of death in the world and projected to be the 3rd leading cause of death by 2020. COPD and cardiac comorbidities are frequently associated. They share common risk factors, pathophysiological processes, signs and symptoms, and act synergistically as negative prognostic factors. Cardiac disease includes a broad spectrum of entities with distinct pathophysiology, treatment and prognosis. From an epidemiological point of view, patients with COPD are particularly vulnerable to cardiac disease. Indeed, mortality due to cardiac disease in patients with moderate COPD is higher than mortality related to respiratory failure. Guidelines reinforce that the control of comorbidities in COPD has a clear benefit over the potential risk associated with the majority of the drugs utilized. On the other hand, the true survival benefits of aggressive treatment of cardiac disease and COPD in patients with both conditions have still not been clarified. Given their relevance in terms of prevalence and prognosis, we will focus in this paper on the management of COPD patients with ischemic coronary disease, heart failure and dysrhythmia.Novartis Portugal Novartisinfo:eu-repo/semantics/publishedVersio

Automatic speaker segmentation using multiple features and distance measures: a comparison of three approaches

This paper addresses the problem of unsupervised speaker change detection. Three systems based on the Bayesian Information Criterion (BIC) are tested. The first system investigates the AudioSpectrumCentroid and the AudioWaveformEnvelope features, implements a dynamic thresholding followed by a fusion scheme, and finally applies BIC. The second method is a real-time one that uses a metric-based approach employing the line spectral pairs and the BIC to validate a potential speaker change point. The third method consists of three modules. In the first module, a measure based on second-order statistics is used; in the second module, the Euclidean distance and T2 Hotelling statistic are applied; and in the third module, the BIC is utilized. The experiments are carried out on a dataset created by concatenating speakers from the TIMIT database, that is referred to as the TIMIT data set. A comparison between the performance of the three systems is made based on t-statistics

Supermassive black holes or boson stars? Hair counting with gravitational wave detectors

The evidence for supermassive Kerr black holes in galactic centers is strong and growing, but only the detection of gravitational waves will convincingly rule out other possibilities to explain the observations. The Kerr spacetime is completely specified by the first two multipole moments: mass and angular momentum. This is usually referred to as the ``no-hair theorem'', but it is really a ``two-hair'' theorem. If general relativity is the correct theory of gravity, the most plausible alternative to a supermassive Kerr black hole is a rotating boson star. Numerical calculations indicate that the spacetime of rotating boson stars is determined by the first three multipole moments (``three-hair theorem''). LISA could accurately measure the oscillation frequencies of these supermassive objects. We propose to use these measurements to ``count their hair'', unambiguously determining their nature and properties.Comment: 8 pages. This essay received an honorable mention in the Gravity Research Foundation Essay Competition, 200