Problem Of Decay Research Articles

The role of nuclear reactions in the problem of 0νββ decay and the NUMEN project at INFN-LNS

An innovative technique to access the nuclear matrix elements entering the expression of the life time of the double beta decay by relevant cross sections of double charge exchange reactions is proposed. The basic point is the coincidence of the initial and final state wave-functions in the two classes of processes and the similarity of the transition operators, which in both cases present a superposition of Fermi, Gamow-Teller and rank-two tensor components with a relevant implicit momentum transfer. First pioneering experimental results obtained at the INFN-LNS laboratory for the 40Ca(18O,18Ne)40Ar reaction at 270 MeV, give encouraging indication on the capability of the proposed technique to access relevant quantitative information. A key aspect of the project is the use of the K800 Superconducting Cyclotron (CS) for the acceleration of the required high resolution and low emittance heavy- ion beams and of the MAGNEX large acceptance magnetic spectrometer for the detection of the ejectiles. The use of the high-order trajectory reconstruction technique, implemented in MAGNEX, allows to reach the high mass, angular and energy resolution required even at very low cross section. The LNS set-up is today an ideal one for this research even in a worldwide perspective. However a main limitation on the beam current delivered by the accelerator and the maximum rate accepted by the MAGNEX focal plane detector must be sensibly overcome in order to systematically provide accurate numbers to the neutrino physics community in all the studied cases. The upgrade of the LNS facilities in this view is part of this project.

Fast prediction of indoor pollutant dispersion based on reduced-order ventilation models

In order to provide realistic ventilation flow rates, it is of great importance to know indoor pollutant concentration field quickly and efficiently resulting from any type of indoor-pollutant-source distribution, further facilitating the design and control of indoor ventilation systems for practical application. This work introduces the development of reduced-order ventilation models for transient pollutant dispersion. In particular, we focus on transients resulting from a step change in pollutant source distributions. We further focus on the decay problem. A reduced-order ventilation model is the solution for this decay problem, which is derived from a large coupled system of Ordinary Differential Equations (ODEs) for concentration that can be cast in terms of a matrix exponential, that is accurately represented with only a few dominant eigenmodes. Using a 2D ventilation case, dominant eigenmodes with their physical relevance and pollutant concentration results are presented. We find that the first 4 eigenmodes are sufficient to predict the pollutant concentration decay for the current test case. We also find that the complex eigenmodes play an important role in the indoor recirculation processes.

Adaptive finite difference solutions of Liouville equations in computational uncertainty quantification

In the context of computational uncertainty quantification, we present a finite difference based solution of a Liouville equation that describes the evolution of a conditional probability density function depending on state variables and model input parameters. The efficiency of the numerical solution is enhanced through (i) a quadrature-based sampling of random variables corresponding to model input parameters and (ii) time-adaptive methods for determining the computational grid in the space of state or response variables. The proposed method, which allows for accurate and computationally efficient determination of the conditional density and resulting statistical moments, is applied to a decay problem and a problem which contains nonlinear deterministic dynamics with multiple equilibrium points. Through comparison with exact solutions and direct numerical simulation on a fixed time-invariant grid, it is demonstrated that the proposed methodology not only is able to accurately predict the large time behavior of the response density but also can significantly reduce the computational costs.

On dissociation in weakly doped ice

Currently, there is some ambiguity in the problem of decay of a single donor into charged fragments. Thus, in the well-known Ostwald approximation used for semiconductors (ice being one of them) the donor dissociation degree of tends to its maximum value (i.e., unity) as the doping impurity concentration approaches zero. At the same time, the statistical theory of atom reveals within the Thomas–Fermi (or Debye–Hückel) approximation the existence of a thermodynamically equilibrium state of a single multi-electron atom (donor) where charged nucleus keeps the number of counterions just necessary for its neutralization. These scenarios do not show the atom dissociation at all. Discussed in the present paper is the alternative between the full dissociation of a single donor (i.e., dissociation degree equals unity) in a semiconducting media (ice, water, semiconductor) and zero dissociation degree.

Cosmology with a decaying vacuum energy parametrization derived from quantum mechanics

Within the quantum mechanical treatment of the decay problem one finds that at late times tthe survival probability of an unstable state cannot have the form of an exponentially decreasing function of time t but it has an inverse power-like form. This is a general property of unstable states following from basic principles of quantum theory. The consequence of this property is that in the case of false vacuum states the cosmological constant becomes dependent on time: Λ — Λbare ≡ Λ(t) — Λbare ∼ 1/t2. We construct the cosmological model with decaying vacuum energy density and matter for solving the cosmological constant problem and the coincidence problem. We show the equivalence of the proposed decaying false vacuum cosmology with the Λ(t) cosmologies (the Λ(t)CDM models). The cosmological implications of the model of decaying vacuum energy (dark energy) are discussed. We constrain the parameters of the model with decaying vacuum using astronomical data. For this aim we use the observation of distant supernovae of type Ia, measurements of H(z), BAO, CMB and others. The model analyzed is in good agreement with observation data and explain a small value of the cosmological constant today.

Efficient heat transfer in a regime of elastic turbulence

By systematic measurements of the statistics of temperature fluctuations at various positions within a viscoelastic von Karman flow driven at a Reynolds number at which no inertial instability is observed with the pure solvent and cooled from below it is found that within an elastic turbulent flow regime the heat transfer efficiency may locally increase up to 4 times (as compared to the purely conductive state) which is comparable to the efficiency increase observed in the case of inertial turbulence at Re≈1600. In spite of the inhomogeneous rheological properties induced by the temperature gradient, several similarities with the decay of a low diffusivity tracer in a random smooth flow (Batchelor regime) are found: exponential tails of the probability distribution functions, algebraic decay of the power spectra, P∝f-β with β≈-1.1, exponential decay of the second order moment of the fluctuations. The similarity with the passive scalar decay problem is reinforced by a comparative analysis of the isothermal and non-isothermal flow patterns which reveals no significant effect of the heat transfer process on the flow topology.

State or market: the role of the government in urban village regeneration in China

Urban regeneration is a natural response of recycling resources in our urban development strategy to the problem of urban decay. Since urban regeneration invariably involves property rights as well as wealth redistribution, it usually lends itself to a tight scrutiny by the society even though some actors in the process may claim that renewal of old and obsolete physical structures is merely a normal economic activity that can be accommodated effectively within the market mechanism. Urban regeneration therefore becomes a complex process that involves intriguing interaction among various stakeholders in dealing with spatial reorganization due to urban physical and economic decay. In this paper, we will first examine the literature on the state–market dynamics, followed by a general discussion of urban regeneration against the backdrop of the interaction between the state and the market. Finally, the discussion of such state–market interaction will be channelled to a more focused spatial context of regenerating urban villages in China. In doing so, we hope to contribute to the current literature on how the state, stakeholders and the market interact during this complex process of regeneration.

Rehearsal in serial recall: An unworkable solution to the nonexistent problem of decay.

We examine the explanatory roles that have been ascribed to various forms of rehearsal or refreshing in short-term memory (STM) and working memory paradigms, usually in conjunction with the assumption that memories decay over time if they are not rehearsed. Notwithstanding the popularity of the rehearsal notion, there have been few detailed examinations of its underlying mechanisms. We explicitly implemented rehearsal in a decay model and explored its role by simulation in several benchmark paradigms ranging from immediate serial recall to complex span and delayed recall. The results show that articulatory forms of rehearsal often fail to counteract temporal decay. Rapid attentional refreshing performs considerably better, but so far there is scant empirical evidence that people engage in refreshing during STM tasks. Combining articulatory rehearsal and refreshing as 2 independent maintenance processes running in parallel leads to worse performance than refreshing alone. We conclude that theoretical reliance on articulatory rehearsal as a causative agent in memory may be unwise and that explanatory appeals to rehearsal are insufficient unless buttressed by quantitative modeling.

Supplemental Material for Rehearsal in Serial Recall: An Unworkable Solution to the Nonexistent Problem of Decay

Supplemental Material for Rehearsal in Serial Recall: An Unworkable Solution to the Nonexistent Problem of Decay

Perspectives on Seminal Achievements and Challenges in the Field of Emotional and Behavioral Disorders

This commentary for a special issue of Remedial and Special Education (RASE) on the perspectives of senior scholars (a) opens with some comments regarding the role of measures we use in behavioral science to pursue scientific truth and then (b) discusses the three most impactful developments in emotional and behavioral disorders over the past several decades, followed by commentary on three problems or issues that need addressing going forward. In the author’s view, the three most impactful developments have been the advent of school-wide positive behavior supports, the growth in approaches to conduct universal behavioral disorder screenings in schools, and the acceptance of teacher judgment in the appraisal of student behavior. Challenges going forward are the need to contextualize school interventions, solve the problem of decay of achieved intervention effects over time, and plan/manage school transitions better.

‘The cunning of their ground’: The Relevance of <i>Sejanus</i> to Renaissance Tragedy

Modelled on contemporary metatheatrical tragedies such as Tamburlaine and Richard III, Sejanus is Jonson’s riposte to these rebellious innovations to tragedy illustrating that his peers have failed to resolve substantially the problem of generic decay. Sejanus, modelled on the anarchic heroes of Marlowe and Shakespeare, satirizes these figures, while the play’s rigid decorum demonstrates the structural discipline necessary to produce tragedy’s moral function. Sejanus enacts Jonson’s criticism of the ‘corrupt’ context of early modern tragedy, its characters and argument the result of a decayed ethos in which the use of performance has corroded both gesture and interpretation into cynicism, and in which true heroism, and true tragedy, are impossible.

Zeno and anti-Zeno effects on dephasing

Quantum Zeno and anti-Zeno effects on pure dephasing are studied using exactly solvable microscopic models. The crossover between these two opposite effects is investigated. The case of a single two-level system undergoing dephasing is already different from the previously studied population decay problem, even without taking into account any back action from the environment. For many two-level systems interacting with a common environment, multiple transitions between Zeno and anti-Zeno regimes are predicted. Finally, if the system-environment coupling strength is not weak, we show that the nontrivial evolution of the environment between measurements can considerably alter the quantum Zeno and anti-Zeno effects.

Escape dynamics of a Bose-Hubbard dimer out of a trap

We consider a potential scattering of Bose-Hubbard dimer in 1D optical lattice. A numerical approach based on effective non-Hermitian Hamiltonian has been developed for solving the scattering problem. It allows to compute the tunneling and dissociation probabilities for arbitrary shape of the potential barrier and arbitrary kinetic energy of the dimer. The developed approach has been used to address the problem of two-particle decay out of a trap. In particular, it is shown that the presence of dissociation channels significantly decreases non-escape probability due to single-particle escape to those channels.

The nonlinear decay of vortex flows in a rotating fluid

The manifestations of the cyclone-anticyclone asymmetry effect, which is observed in nature [1–3] and in laboratory experiments with a rotating fluid [4–6], have been studied in the scope of the vorticity evolution generalized equation. Under laboratory conditions, asymmetry is observed as a faster decay of cyclonic vortices as compared to anticyclonic ones. This effect has been analytically described simply based on the problem of the vortex spot decay and spatially periodic vortex lattice. It has been indicated that anticyclonic vortices compress and cyclonic ones expand when a lattice damps. Examples of exact solutions of the vorticity equation [7] (describing, specifically, collapsing of an axisymmetric vortex core with anticyclonic vorticity) have been constructed. The effect of the Ekman friction on the interaction between singular vortices is discussed.

B(E2) Evaluation for [formula omitted] Transitions in Even-Even Nuclei

A collaborative study by Brookhaven-McMaster-Central Michigan is underway to evaluate B(E2)↑ for 01+→21+ transitions. This work is a continuation of a previous USNDP evaluation and has been motivated by a large number of recent measurements and nuclear theory developments. It includes an extended compilation, data evaluation procedures and shell model calculations. The subset of B(E2)↑ recommended values for nuclei of relevance to the double-beta decay problem is presented, and evaluation policies of experimental data and systematics are discussed. Future plans for completion of the B(E2;01+→21+) evaluation project are also described.

DYNAMICAL FRICTION IN CUSPY GALAXIES

In this paper we treat the problem of the dynamical friction decay of a massive object moving in an elliptical galaxy with a cuspidal inner distribution of the mass density. We present results obtained by both self-consistent, direct summation, N-body simulations, as well as by a new semi-analytical treatment of dynamical friction valid in such cuspy central regions of galaxies. A comparison of these results indicates that the proposed semi-analytical approximation is the only reliable in cuspy galactic central regions, where the standard Chandrasekhar's local approximation fails, and, also, gives estimates of decay times that are correct at 1% respect to those given by N-body simulations. The efficiency of dynamical friction in cuspy galaxies is found definitively higher than in core galaxies, especially on more radially elongated satellite orbits. As another relevant result, we find a proportionality of the dynamical friction decay time to the -0.67 power of the satellite mass, M, shallower than the standardly adopted 1/M dependence.

SOLAR SYSTEM TESTS OF f(R) GRAVITY

In this paper, we revisit the solar system tests of f(R) gravity. When the sun sits in a vacuum, the field f′ is light, which leads to a metric different from the observations. We reobtain this result in a simpler way by directly focusing on the equations of motion for f(R) gravity in the Jordan frame (JF). The discrepancy between the metric in the f(R) gravity and the observations can be alleviated by the chameleon mechanism. The implications from the chameleon mechanism on the functional form f(R) are discussed. Considering the analogy of the solar system tests to the false vacuum decay problem, the effective potentials in different cases are also explored. The combination of analytic and numerical approaches enables us to ascertain whether an f(R) model can pass the solar system tests or not.

Smart design of lithium-rich layered oxide cathode compositions with suppressed voltage decay

The lithium-rich layered oxide cathodes offer a high capacity of ∼250 mA h g−1, but their commercialization is prevented by the problem of voltage decay during cycling, originating from a phase transformation to a 3 V spinel-like phase. With an aim of understanding the factors that govern the voltage decay, the effect of the length of the plateau region during first charge and the octahedral-site stabilization energy of the transition metal (TM) ions has been investigated by designing various compositions of lithium-rich layered oxides. Charge–discharge profile and dQ/dV plot variations during cycling confirm that the length of the plateau region during first charge is the primary governing factor in the voltage decay process. The voltage decay is enhanced by a lengthened plateau region that increases the kinetics of the phase transformation to the spinel-like phase due to the (i) formation of Litet–V(TM)Li–Litet dumbbells (Litet refers to the lithium ion in a tetrahedral site and V(TM)Li refers to the lithium-ion vacancy in the TM layer) because of the increased lithium-ion extraction from the TM layer and (ii) TM migration to the lithium layer assisted by a higher oxygen vacancy concentration. Based on this understanding, a new series of compositions Li1.2−xMn0.54Ni0.13+2xCo0.13−xO2 have been designed to minimize the plateau region during first charge without sacrificing the energy density. The optimized composition Li1.15Mn0.54Ni0.23Co0.08O2 exhibits superior electrochemical performance with a marked decrease in voltage decay during cycling compared to the well-known composition Li1.2Mn0.54Ni0.13Co0.13O2.

Riots, Restraint and the New Cultural Politics of Wanting

In the aftermath of the 2011 English riots, many political elites, journalists and public commentators obscured the material, sociological and economic factors which contributed to the unrest and instead connected the riots to a problematic kind of ‘wanting’ – wanting the wrong kinds of things, in a manner and degree that was constructed as illegitimate and vulgar in a time of austerity – and thus constructing the riots as a problem of excessive greed, rampant materialism and social decay. This article reflects upon how the riots played a key role in the political production of a new cultural politics of wanting, whereby wanting is made problematic, suspect, a sign of material fixation and of irresponsible consumerism. It reflects upon this cultural politics within the current austerity regime which manifests through a celebration and romanticisation of post-War restraint and re-animation of thrift practices and frugal living.

Reverberation in a trapezoidal room

The problem of sound decay in a trapezoidal room with a nonuniform distribution of wall absorption is considered. It is shown that the sound energy decay may be either anomalously slow, obeying the law ∼1/t, or fast, obeying an exponential law. It is found that the type of the decay law depends on the presence of stable ray trajectories in the room. Manifestations of stable ray trajectories in both laboratory and field experiments are demonstrated.