Deformability of discs in turbulence

The aim of this study is to investigate experimentally the transition from a rigid regime to a deformed regime for flexible discs freely advected in turbulent flows. For a given disc, the amplitude of the deformation is expected to increase when its bending modulus decreases or when the turbulent kinetic energy increases. To quantify this qualitative argument, experiments are performed where the deformation of flexible discs is measured using three cameras. The amplitude of the deformation has been characterised by the eigenvalues of the moment of inertia tensor. Experimental results exhibit a transition from a rigid regime to a deformed regime that depends on the size, the density and the flexibility of the disc and the turbulent kinetic energy. The modelling of this transition is a generalisation and an extension of the previous models used to characterise the deformation of flexible fibres in turbulent flows.

Which is a Better Method for Reporting Cash Flows from Operating Activities-Direct or Indirect Method?

This paper is a response to the ongoing debate in the accounting profession on whether the direct method is better than the indirect method when reporting cash flows from operating activities. The debate has its roots from the standard setters who prefer the direct method and are even debating on whether to make the direct method mandatory. The contention being that the direct method is a better method than the indirect method when reporting cash flows from operating activities since the disaggregation of its components suggests more disclosure. More disclosure in financial statements has been a cry from the financial statement users such as the creditors and investors. This qualitative argument will therefore show the merits of both the direct and the indirect method before getting to a conclusion on which method is better than the other. Further, it is a contribution to the ongoing debate in the accounting profession that can guide the standard setters as they deliberate on the possibility of making the direct method mandatory. In addition, a contention map and an argument map are used as roadmaps of the ideas being discussed in this study.

Whenever a quantum environment emerges as a classical system, it behaves like a measuring apparatus

We study the dynamics of a quantum system Γ with an environment Ξ made of N elementary quantum components. We aim at answering the following questions: can the evolution of Γ be characterized by some general features when N becomes very large, regardless of the specific form of its interaction with each and every component of Ξ? In other terms: should we expect all quantum systems with a macroscopic environment to undergo a somehow similar evolution? And if yes, of what type? In order to answer these questions we use well established results from large-N quantum field theories, particularly referring to the conditions ensuring a large-N quantum model to be effectively described by a classical theory. We demonstrate that the fulfillment of these conditions, when properly imported into the framework of the open quantum systems dynamics, guarantees that the evolution of Γ is always of the same type of that expected if Ξ were a measuring apparatus, no matter the details of the actual interaction. On the other hand, such details are found to determine the specific basis w.r.t. which Γ undergoes the decoherence dictated by the dynamical description of the quantum measurement process. This result wears two hats: on the one hand it clarifies the physical origin of the formal statement that, under certain conditions, any channel from ρΓ to ρΞ takes the form of a measure-and-prepare map, as recently shown in Ref. \cite{BrandaoPH15}; on the other hand, it formalizes the qualitative argument that the reason why we do not observe state superpositions is the continual measurement performed by the environment.

The emergence of the principle of symmetry in physics

ABSTRACT: In 1894 Pierre Curie formulated rules for relations between physical phenomena and their symmetry. The symmetry concept originated in the geometrical study of crystals, which it served as a well-defined concept from the 1830s. Its extension as a rule for all physics was a gradual and slow process in which applications, though often partial, preceded the formulation and clear conceptualization of the rules. Two traditions that involved ““interdisciplinary”” study were prominent in applying consideration of symmetry to physics. One is a French tradition of physical crystallography that linked crystalline structure and form to their physical, chemical and even biological qualities, which drew back to Haüüy, and included Delafosse, Pasteur, Senarmont, and Curie. This tradition (until Curie) employed qualitative argument in deducing physical properties. A mathematical approach characterizes the second tradition of Franz Neumann and his students. During the 1880s two members of this tradition, Minnigerode and Voigt, formulated rules of symmetry and implicitly recognized their significance. Yet, until 1894 both traditions studied only crystalline or other asymmetric matter. Then, Curie, who drew on the two traditions, extended the rules of symmetry to any physical system including fields and forces. Although originated in a specific idealistic ontological context, symmetry served also adherents of molecular materialism and was eventually found most effective for a phenomenological approach, which avoided any commitment to a specific view of nature or causal processes. Therefore, the rule of symmetry resembles the principles of thermodynamics. Its emergence suggests parallels to the history of energy conservation.

FACTORIZATION IN EXCLUSIVE AND SEMI-INCLUSIVE HEAVY FLAVOR DECAYS AND EFFECTIVE THEORIES FOR MASSLESS PARTICLES

We prove factorization in the semi-inclusive decay B → D(*) + jet using the Large Energy Effective Theory (LEET). It is also shown that the LEET is unable to consistently describe exclusive processes, such as the decay B → D(*) + π(ρ), and therefore also related properties such as factorization. The reason is an oversimplification of transverse momentum dynamics. We present a variant of the LEET, i.e. a new effective theory for massless particles, the [Formula: see text], which properly takes into account transverse momentum dynamics and is the natural framework to study exclusive nonleptonic decays. The transition from the LEET to the [Formula: see text] is analogous to the replacement of geometrical optics with physical optics, the latter taking into account diffraction to a first approximation. A qualitative argument is presented in favor of factorization in the exclusive nonleptonic decays using the [Formula: see text]. Finally, it is shown that the collinear instability of the LEET disappears when semi-inclusive observables are considered.

QUANTUM CORRECTIONS TO ENTROPY OF CHARGED DILATONIC BLACK HOLES IN ARBITRARY DIMENSIONS

The quantum contribution of a scalar field to entropy of a dilatonic black hole is calculated in the brick wall model by the WKB method and analyzed by a high-temperature expansion. If the cutoff distance from the horizon approaches zero, the leading divergent piece of entropy turns out to be proportional to the “area” of the horizon surface (which has (N−1)-dimensional extension in (N+1)-dimensional space-time) and independent of other properties of black holes even in the case of general dilaton coupling. There is also qualitative argument with the known result of subleading divergence for N=3.

Cyclic AMP oscillations in suspensions of Dictyostelium discoideum

A model developed previously for signal relay and adaptation in the cellular slime mould Dictyostelium discoideum is shown to account for the observed oscillations of calcium and cyclic AMP in cellular suspensions. A qualitative argument is given which explains how the oscillations arise, and numerical computations show how characteristics such as the period and amplitude of the periodic solutions depend on parameters in the model. Several extensions of the basic model are investigated, including the effect of cell aggregation and the effect of time delays in the activation and adaptation processes. The dynamics of mixed cell populations in which only a small fraction of the cells are capable of autonomous oscillation are also studied.

Sharp edges of planetary rings

The ring systems of Saturn and Uranus exhibit a number of sharp edges across which the optical depth drops from order unity to near zero. At least two and perhaps all of these features are associated with the location of orbital resonances between a satellite and a ring particle. It is remarkable that the optical depth varies on a distance scale which is much finer than that over which angular momentum can be transferred between a satellite and the ring material. We illustrate here with qualitative argument the results of a numerical simulation concerning the outer edge of the B ring. More details can be found in Borderies, Goldreich and Tremaine (1982).