Set Of Transition Probabilities Research Articles

Update of Atomic Data for the First Three Spectra of Actinium.

The present article describes a complete reanalysis of all published data on observed spectral lines and energy levels of the first three spectra of actinium (Ac I-III). In Ac I, three previously determined energy levels have been rejected, 12 new energy levels have been found; for six previously known levels, either the J values or the energies have been revised, and the ionization energy has been redetermined with an improved accuracy. In the line list of Ac I, three previous classifications have been discarded, 16 new ones have been found, and three have been revised. In Ac II, 16 new energy levels have been established, and 36 new identifications have been found for previously observed but unclassified lines. In both Ac I and Ac II, new sets of transition probabilities have been calculated. For all three spectra, complete datasets of critically evaluated energy levels, observed lines, and transition probabilities have been constructed to serve as recommended data on these spectra.

Exploring AoA/AoD Dynamics in Beam Alignment of Mobile Millimeter Wave MIMO Systems

In this paper, we present a priori-aided beam alignment scheme for time-varying millimeter wave multiple-input multiple-output (MIMO) systems, where the temporal correlations of the angle of departure (AoD) and angle of arrival (AoA) of the propagation path are exploited. Specifically, the variations of AoD and AoA between two consecutive channel realizations are described by a set of transition probabilities, respectively, which characterize the temporal correlations. We aim to maximize the average successful estimation probability (ASEP) by jointly optimizing the selected transmitting–receiving training beam pairs and their associated transmit power. When the transition probabilities are known, this problem is formulated as a mixed integer nonlinear programming (MINLP). Due to the non-convex nature of the formulated MINLP, we propose a semi-exhaustive search algorithm (SESA) to obtain a suboptimal solution. Moreover, in order to achieve maximum ASEP, we prove that the training beam pairs corresponding to the directions which have higher transition probabilities should be used more times than those with lower transition probabilities. Numerical results show that the proposed joint optimization with the SESA can achieve a higher ASEP than the existing works.

Experimental and Theoretical Radiative Lifetimes, Branching Fractions, Transition Probabilities, and Oscillator Strengths of Some Highly Excited Odd-parity Levels in Ir i

Abstract Radiative lifetimes of 62 odd-parity levels of Ir i in the energy range between 32513.43 and 58625.10 cm−1 were measured using the time-resolved laser-induced fluorescence technique. The lifetime values obtained are in the range from 3.2 to 345 ns. To our best knowledge, 59 results are reported for the first time. These are compared to computed data deduced from a pseudo-relativistic Hartree–Fock model including core-polarization contributions. From the combination of the experimental lifetime measurements and branching fraction calculations, a new set of transition probabilities and oscillator strengths is derived for 134 Ir i spectral lines of astrophysical interest in the wavelength region from 205 to 418 nm.

Transition probabilities of Ce I obtained from Boltzmann analysis of visible and near-infrared emission spectra

We report radiative transition probabilities for 5029 emission lines of neutral cerium within the wavelength range 417–1110 nm. Transition probabilities for only 4% of these lines have been previously measured. These results are obtained from a Boltzmann analysis of two high resolution Fourier transform emission spectra used in previous studies of cerium, obtained from the digital archives of the National Solar Observatory at Kitt Peak. The set of transition probabilities used for the Boltzmann analysis are those published by Lawler et al (2010 J. Phys. B: At. Mol. Opt. Phys. 43 085701). Comparisons of branching ratios and transition probabilities for lines common to the two spectra provide important self-consistency checks and test for the presence of self-absorption effects. Estimated 1σ uncertainties for our transition probability results range from 10% to 18%.

What cervical screening is appropriate for women who have been vaccinated against high risk HPV? A simulation study.

Women vaccinated against HPV16/18 are approaching the age for cervical screening; however, an updated screening algorithm has not been agreed. We use a microsimulation model calibrated to real published data to determine the appropriate screening intensity for vaccinated women. Natural histories in the absence of vaccination were simulated for 300,000 women using 10,000 sets of transition probabilities. Vaccination with (i) 100% efficacy against HPV16/18, (ii) 15% cross‐protection, (iii) 22% cross‐protection, (iv) waning vaccine efficacy and (v) 100% efficacy against HPV16/18/31/33/45/52/58 was added, as were a range of screening scenarios appropriate to the UK. To benchmark cost‐benefits of screening for vaccinated women, we evaluated the proportion of cancers prevented per additional screen (incremental benefit) of current cytology and likely HPV screening scenarios in unvaccinated women. Slightly more cancers are prevented through vaccination with no screening (70.3%, 95% CR: 65.1–75.5) than realistic compliance to the current UK screening programme in the absence of vaccination (64.3%, 95% CR: 61.3–66.8). In unvaccinated women, when switching to HPV primary testing, there is no loss in effectiveness when doubling the screening interval. Benchmarking supports screening scenarios with incremental benefits of ≥2.0%, and rejects scenarios with incremental benefits ≤0.9%. In HPV16/18‐vaccinated women, the incremental benefit of offering a third lifetime screen was at most 3.3% (95% CR: 2.2–4.5), with an incremental benefit of 1.3% (−0.3–2.8) for a fourth screen. For HPV16/18/31/33/45/52/58‐vaccinated women, two lifetime screens are supported. It is important to know women's vaccination status; in these simulations, HPV16/18‐vaccinated women require three lifetime screens, HPV16/18/31/33/45/52/58‐vaccinated women require two lifetime screens, yet unvaccinated women require seven lifetime screens.

Future trends of Japanese households through micro-simulation model--an application of INAHSIM.

"INAHSIM (Integrated Analytical Model for Household Simulation) is a micro simulation model, which was first developed in 1984-85 by using actual initial population and a set of transition probabilities derived from vital statistics and other national sample surveys.... This paper is based on a new application of INAHSIM, where initial population of the model has been prepared by using the simulation model itself. In this way, it is confirmed that INAHSIM is applicable to countries where initial population is not available from census or national household surveys.... New simulations were executed for [Japan for] the period of 1991-2040." (SUMMARY IN JPN)

The impact of atomic data selection on nebular abundance determinations

Atomic data are an important source of systematic uncertainty in our determinations of nebular chemical abundances. However, we do not have good estimates of these uncertainties since it is very difficult to assess the accuracy of the atomic data involved in the calculations. We explore here the size of these uncertainties by using 52 different sets of transition probabilities and collision strengths, and all their possible combinations, to calculate the physical conditions and the total abundances of O, N, S, Ne, Cl and Ar for a sample of planetary nebulae and H ii regions. We find that atomic data variations introduce differences in the derived abundance ratios as low as 0.1–0.2 dex at low density, but that reach or surpass 0.6–0.8 dex at densities above 104 cm−3 in several abundance ratios, like O/H and N/O. Removing from the 52 data sets the four data sets that introduce the largest differences, the total uncertainties are reduced, but high-density objects still reach uncertainty factors of four for their values of O/H and N/O. We identify the atomic data that introduce most of the uncertainty, which involves the ions used to determine density, namely, the transition probabilities of the S+, O+, Cl++ and Ar+3 density diagnostic lines, and the collision strengths of Ar+3. Improved calculations of these data will be needed in order to derive more reliable values of chemical abundances in high-density nebulae. In the meantime, our results can be used to estimate the uncertainties introduced by atomic data in nebular abundance determinations.

Radiative data for highly excited 3d84d levels in Ni II from laboratory measurements and atomic calculations

This work reports new experimental radiative lifetimes and calculated oscillator strengths for transitions from 3d8 4d levels of astrophysical interest in singly ionized nickel. Radiative lifetimes of seven high-lying levels of even parity in Ni II (98400 -100600 cm-1) have been measured using the time-resolved laser-induced fluorescence method. Two-step photon excitation of ions produced by laser ablation has been utilized to populate the levels. Theoretical calculations of the radiative lifetimes of the measured levels and transition probabilities from these levels are reported. The calculations have been performed using a pseudo-relativistic Hartree-Fock method, taking into account core polarization effects. A new set of transition probabilities and oscillator strengths has been deduced for 477 Ni II transitions of astrophysical interest in the spectral range 194 - 520 nm depopulating even parity 3d8 4d levels. The new calculated gf-values are, on the average, about 20 % higher than a previous calculation by Kurucz (http://kurucz.harvard.edu) and yield lifetimes within 5 % of the experimental values.

Improved and expanded measurements of transition probabilities in UV Ar ii spectral lines

Transition probabilities have a significant interest in the astrophysical field. The aim of this experiment is to extend the present data base of measured Ar II transition probabilities to the ultraviolet (UV) region and to improve the quality of some of the already existing data. Despite all the efforts made to assemble an accurate set of transition probabilities (Aki), some of the data recommended by the National Institute of Standards and Technology (NIST) for Ar II spectral lines in the UV region have uncertainties around 50percent. We measured relative intensities of spectral lines emitted from a low-pressure-pulsed discharge lamp which generates an argon plasma. Excitation temperatures of 19 000–22 000 K are determined from the Boltzmann-plot of 11 Ar II spectral lines for which accurate Aki data are available from the literature. The transition probabilities of these 11 spectral lines were used for calculating new Aki-values. Electron densities (Ne) of 3.5–9.0 × 10 22 m −3 are determined by two-wavelength interferometry method. The measurements yield to a collection of 43 atomic transition probabilities of Ar II lines in the spectral region of 294–386 nm, 11 of which are new, at least up to the authors knowledge, and 22 improved Aki-values for which the existing data in the literaturehaveuncertaintiesaround50percent.Comparisonwithprevious datashowshowour measurements have good agreement with the most accurate Aki-values from the bibliography, whereas some of the values recommended by NIST present a significant disagreement.

RADIATIVE LIFETIMES OF V I AND V II

New radiative lifetimes are reported for 168 levels of V I ranging in energy from 18086 cm–1 to 47702 cm–1, and for 31 levels of V II ranging in energy from 34593 cm–1 to 47420 cm–1. These lifetimes are measured using time-resolved laser-induced fluorescence on a slow atomic/ionic beam as part of an ongoing study of the radiative properties of the iron group elements. All but two of the V II lifetimes have been measured before using modern laser-based methods, but a large fraction of the V I lifetimes are reported here for the first time. Comparison to earlier measurements is discussed. These new lifetimes are, for the most part, accurate to ±5%. They will be combined with branching fraction measurements to produce a large set of transition probabilities for V I and V II which are needed by the astrophysics community for stellar abundance determinations.

0380 Dynamics of Exposure and Disease Progression: The Use of Compartmental Models

ObjectivesChronic diseases are usually slow-developing condition and their risk may result from both long-term exposure and successive exposure increments, hence calling for models accounting for dynamics of exposure and disease...

Analysis of exposure–response of CI-945 in patients with epilepsy: application of novel mixed hidden Markov modeling methodology

We propose to describe exposure-response relationship of an antiepileptic agent, using mixed hidden Markov modeling methodology, to reveal additional insights in the mode of the drug action which the novel approach offers. Daily seizure frequency data from six clinical studies including patients who received gabapentin were available for the analysis. In the model, seizure frequencies are governed by underlying unobserved disease activity states. Individual neighbouring states are dependent, like in reality and they exhibit their own dynamics with patients transitioning between low and high disease states, according to a set of transition probabilities. Our methodology enables estimation of unobserved disease dynamics and daily seizure frequencies in all disease states. Additional modes of drug action are achievable: gabapentin may influence both daily seizure frequencies and disease state dynamics. Gabapentin significantly reduced seizure frequencies in both disease activity states; however it did not significatively affect disease dynamics. Mixed hidden Markov modeling is able to mimic dynamics of seizure frequencies very well. It offers novel insights into understanding disease dynamics in epilepsy and gabapentin mode of action.

Comparative semi-empirical and ab initio atomic structure calculations in Yb-like tungsten W4 +

In this paper, we report on extensive calculations of radiative data in Yb-like tungsten ion using several independent atomic structure methods, i.e. the relativistic Hartree–Fock approach, the flexible atomic code and the multiconfiguration Dirac–Fock method. This multi-platform approach allowed us to check the consistency of our results. Advantages and shortcomings of semi-empirical and ab initio methods for atomic structure calculations in such a complex heavy ion are also discussed in detail. A new set of transition probabilities and oscillator strengths is reported for electric dipole lines together with magnetic dipole and electric quadrupole lines in this ion of interest for fusion plasma diagnostics.

Some aspects of modeling dependence in copula-based Markov chains

Dependence coefficients have been widely studied for Markov processes defined by a set of transition probabilities and an initial distribution. This work clarifies some aspects of the theory of dependence structure of Markov chains generated by copulas that are useful in time series econometrics and other applied fields. The main aim of this paper is to clarify the relationship between the notions of geometric ergodicity and geometric ρ-mixing; namely, to point out that for a large number of well known copulas, such as Clayton, Gumbel or Student, these notions are equivalent. Some of the results published in the last years appear to be redundant if one takes into account this fact. We apply this equivalence to show that any mixture of Clayton, Gumbel or Student copulas generates both geometrically ergodic and geometric ρ-mixing stationary Markov chains, answering in this way an open question in the literature. We shall also point out that a sufficient condition for ρ-mixing, used in the literature, actually implies Doeblin recurrence.

The cost-effectiveness of bevacizumab plus cisplatin and gemcitabine (BCG) compared with pemetrexed plus cisplatin (PC) induction treatment of advanced non-squamous non-small cell lung cancer (NSCLC) in Germany.

e18054 Background: New treatment options for advanced NSCLC can offer improved survival over standard chemotherapy (CT) but should also offer value for money. Bevacizumab, a humanized monoclonal antibody directed against VEGF has been shown to increase overall survival and time to progression in patients (pts) with advanced NSCLC when combined with CT compared with CT alone. Pemetrexed, a thymidylate synthase inhibitor, in combination with cisplatin has shown survival benefit over cisplatin plus gemcitabine. This analysis evaluated the cost-effectiveness of BCG compared with PC in Germany. Methods: A Markov model was used to evaluate the average costs and benefits of treating pts with advanced or recurrent NSCLC with either BCG or PC. The characteristics of an average German hospital pt (80 kg) were applied. The model assumes pts move from pre-progressive to progressed disease to death, according to a set of transition probabilities derived from the respective pivotal trials and appropriate indirect compa...

Generalized rule for the addition of entropies for underdetermined data

Underdetermined data are faced in many areas of computer science. It is of interest to determine which relations in information theory can be extended to underdetermined data (and in which form). In [1] (a brief exposition can be found in [2]), the entropy properties of underdetermined data were investigated and it was found that some of them coincide with the properties of the Shannon entropy, some are their modification, and some are considerably different. In this paper, we analyze the entropy addition rule H ( X ) + H ( Y | X ) = H ( XY ) , which plays an important role in information theory. For general underdetermined data, we show that a modification of this rule, called a generalized entropy addition rule, holds. Some special cases in which the usual entropy addition rule holds can be found in [3]. Let M = {0, 1, …, m – 1} and every T ⊆ M , T ≠ be assigned a symbol a T . The alphabet of all symbols a T is denoted by A , and its subalphabet { a 0 , a 1 , …, a m – 1 } whose symbols correspond to the singletons T is denoted by A 0 . Symbols in A 0 are called basic, while symbols in A are called underdetermined. A specification of a T is any basic symbol a i , i ∈ T . Consider underdetermined sources X that independently generate symbols a T ∈ A with probabilities p ( a T ) ≥ 0 . If p ( a T ) = 0 for all a T ∉ A 0 , then the source is called completely determined. The specification operation for a source X is defined by a set of transition probabilities p ( a i | a T ), T ⊆ M , i ∈ T , ( a i | a T ) = 1. Its application to X gives a completely determined source X ' generating symbols a i with probabilities p '( a i ) = ( a T ) p ( a i | a T ) . The source X ' is called a specification of X . To distinguish the symbols a i of X and X ' , a p iT ∈

Randomized Shortest-Path Problems: Two Related Models

This letter addresses the problem of designing the transition probabilities of a finite Markov chain (the policy) in order to minimize the expected cost for reaching a destination node from a source node while maintaining a fixed level of entropy spread throughout the network (the exploration). It is motivated by the following scenario. Suppose you have to route agents through a network in some optimal way, for instance, by minimizing the total travel cost-nothing particular up to now-you could use a standard shortest-path algorithm. Suppose, however, that you want to avoid pure deterministic routing policies in order, for instance, to allow some continual exploration of the network, avoid congestion, or avoid complete predictability of your routing strategy. In other words, you want to introduce some randomness or unpredictability in the routing policy (i.e., the routing policy is randomized). This problem, which will be called the randomized shortest-path problem (RSP), is investigated in this work. The global level of randomness of the routing policy is quantified by the expected Shannon entropy spread throughout the network and is provided a priori by the designer. Then, necessary conditions to compute the optimal randomized policy-minimizing the expected routing cost-are derived. Iterating these necessary conditions, reminiscent of Bellman's value iteration equations, allows computing an optimal policy, that is, a set of transition probabilities in each node. Interestingly and surprisingly enough, this first model, while formulated in a totally different framework, is equivalent to Akamatsu's model ( 1996 ), appearing in transportation science, for a special choice of the entropy constraint. We therefore revisit Akamatsu's model by recasting it into a sum-over-paths statistical physics formalism allowing easy derivation of all the quantities of interest in an elegant, unified way. For instance, it is shown that the unique optimal policy can be obtained by solving a simple linear system of equations. This second model is therefore more convincing because of its computational efficiency and soundness. Finally, simulation results obtained on simple, illustrative examples show that the models behave as expected.

Lifetime measurements in Ru II and calculated oscillator strengths in Ru II and Ru III

A new set of theoretical f-values is reported for 178 Ru II transitions of astrophysical interest, involving energy levels below 58 000 cm−1. The theoretical model, including core-polarization effects, has been tested by comparing theoretical lifetimes with new measurements performed by time-resolved laser-induced fluorescence spectroscopy for 23 4d6(5D)5p odd levels of Ru II and by comparing theoretical and experimental Landé g-factors. The first set of transition probabilities is proposed for 25 strong lines depopulating the 4d55p5,7P° terms of Ru III. The new results will allow quantitative investigations of stellar spectra and allow the astrophysicists to refine the ruthenium abundance in stars.

Lifetime and transition probability determination in Xe IX

A new set of transition probabilities is proposed for Xe IX. They have been calculated by two different theoretical approaches i.e. a fully relativistic multiconfiguration Dirac–Fock (MCDF) method and a partly relativistic Hartree–Fock (HFR) approach taking core-polarization effects into account. Their accuracy has been evaluated through comparisons with lifetime measurements for 11 levels performed using beams of Xe + ions produced by a 2 MV Van de Graaff accelerator. The agreement theory-experiment is nice for most of the levels and gives more weight to the theoretical models used for the calculations and, consequently, to the new transition probabilities.

Lifetime and transition probability determination in xenon ions

Radiative lifetimes have been calculated for 15 levels of Xe VII belonging to the configurations 5s5p, 5p2, 5s5d, 5s6s, 5p5d, 4f5p, 5p5d and 5s5f and for 4 levels of the 5p and 5d configurations of Xe VIII. A relativistic Hartree-Fock approach including core-polarization effects, on the one hand, and a purely relativistic multiconfiguration Dirac-Fock method, on the other hand, have been used for the calculations. The accuracy of the present set of results has been assessed through comparisons with radiative lifetime measurements obtained by beam-foil spectroscopy. A good agreement between theory and experiment is observed for most of the levels. A new set of transition probabilities is proposed for 169 transitions of Xe VII and 45 transitions of Xe VIII.