Staggering Effects Research Articles

Decay of heavy particles from Z = 125 superheavy nuclei in the region A = 295–325 using different versions of proximity potential

Within the framework of Coulomb and proximity potential model (CPPM), the probable heavy particle decays from various isotopes of superheavy nuclei (SHN), [Formula: see text], within the range [Formula: see text]–[Formula: see text] have been studied using two versions of proximity potential; proximity 1977 and proximity 2000. The decay half lives evaluated using proximity 2000 is observed to be higher than the values obtained using proximity 1977. The effect of surface deformation on the decay half lives is studied using Coulomb and proximity potential for deformed nuclei (CPPMDN). As a result of the inclusion of deformation [Formula: see text], the penetrability of the decays are observed to be increased and accordingly the decay half lives are reduced. The estimated values are compared with other theoretical models, Universal curve (UNIV), Universal Decay law (UDL) and the scaling law of Horoi. The odd–even staggering (OES) effect is observed in the emission of odd mass clusters. An intriguing aspect of the study is the effect of the magicity at [Formula: see text] which is confirmed from the plot of [Formula: see text] against the neutron number of the daughter nuclei. Almost all the predicted half lives are favorable for experimental measurements. The Geiger–Nuttall (GN) plots and the Universal curve have been studied for various cluster emissions from various superheavy isotopes with [Formula: see text]. Finally, the linearity of the GN plot and the Universal curve of the heavy particle emissions very well established the strength of CPPM.

Systematic study of α decay for odd- A nuclei within a two-potential approach

$\alpha$ decay is usually associated with both ground and low-lying isomeric states of heavy and superheavy nuclei, and the unpaired nucleon plays a key role on $\alpha$ decay. In this work, we systematically studied the $\alpha$ decay half-lives of odd-$A$ nuclei, including both favored and unfavored $\alpha$ decay within the two-potential approach based on the isospin dependent nuclear potential. The $\alpha$ preformation probabilities are estimated by using an analytic formula taking into account the shell structure and proton-neutron correlation, and the parameters are obtained through the $\alpha$ decay half-lives data. The results indicate that in general the $\alpha$ preformation probabilities of even-$Z$, odd-$N$ nuclei are slightly smaller than the odd-$Z$, even-$N$ ones. We found that the odd-even staggering effect may play a more important role on spontaneous fission than $\alpha$ decay. The calculated half-lives can well reproduce the experimental data.

Международные аспекты создания Южно-Африканского Союза в 1910 г

The history of South Africa as a unified state is intertwined with the events of international scale. The colonization of South of Africa is linked to the resettlement of the Dutch and the English, engaged in various entrepreneurial activities - trade, mining, agriculture, etc. The formation of South African Union was preceded by a long period when the idea of uniting the British colonial possessions in southern Africa was consistently formed and created by long-term plans. At the same time, several powers competed for economic penetration into South Africa, for instance, albeit to a lesser degree, the United States of America in addition to Germany and England. From 1869 to 1886 the world's largest deposits of diamonds and gold were discovered, which produced a staggering effect on the whole world and radically changed the situation in the region. Conflict of interests in the struggle for control over the richest resources led to war (both campaigns are sometimes called the Boer War), which was the first one in the 20th century. The Anglo-Boer War, the largest international event is of interest from a wide variety of points of view, had left a notable mark in the history of Russia. The Russian government sought to support the Boers and take advantage of the difficulties of their then main rival in the world arena at a time, and the Boers in turn needed the support of world powers in their struggle. Although diplomatic relations with Russia were established the Russian embassy in Pretoria never appeared, due to the fact that a year later the war began. As a result of the war and the processes taking place in the southern part of Africa, emerged the British dominion - South African Union. The approval by the British Parliament of the “South Africa Act” liquidated the last obstacles to the establishment of the Union, and on May 31, 1910, the establishment of a new state, the South African Union, was officially proclaimed. Therefore the socio-economic and political processes that took place in South Africa were reflected in the world politics of that time and had serious consequences of the global scale. They had an important influence in shaping the foreign policy strategy of a new state as yet the dominion of Great Britain.

Design of an order-picking warehouse factoring vertical travel and space sharing

This paper considers the layout design problem of a single block order-picking rack-based warehouse that employs turnover-based storage assignment in both vertical and horizontal dimensions. An analytical expression for vertical travel distance is derived which is incorporated in the pick distance model. The effect of inventory staggering on storage space requirement is considered in arriving at warehouse dimensions. A model that incorporates area cost along with handling cost in optimizing warehouse design is developed and a solution algorithm is presented. The analytical model for vertical travel and the optimization model are applied to data from a real life case. It was found that the model would offer considerable operational cost savings, especially when space costs are high. Computational experiments show that the effect of inventory staggering is quite significant in the estimated storage space. Experiments also demonstrated the importance of segregating products based on turnover in the vertical dimension.

Probable Heavy Particle Decays from 306–339128 Superheavy Nuclei

The heavy particle decays that are probable from the isotopes of Z = 128 superheavy nuclei within the range A = 306–339 have been analyzed within the Coulomb and proximity potential model (CPPM). The study includes the evaluation of heavy particle decay half-lives of 24 clusters, including both odd and even clusters that are supposed to be emitted from the Z = 128 superheavy nuclei. The predicted values in comparison with the models Universal curve (UNIV), Universal decay law (UDL), and scaling law of Horoi et al. are observed to follow the same trend, and almost all the values lie well within the experimental limit (T 1/2 <1030s). The interesting point of the study is the confirmation of the importance of neutron magicity in the superheavy region, noticed from the plots of log10(T 1/2) vs. neutron number of the daughter nuclei. The minimum observed corresponds to the daughter nucleus with N = 184, which strongly supports the possibility of N = 184 to be a shell closure number. Also, the abrupt increase in the half-lives at A = 330 of the parent nuclei is the signature of neutron magicity at N = 202 associated with the parent nuclei. In addition, in the emission of odd mass clusters, the odd–even staggering (OES) effect is found which is more prominent in the case of heavy odd mass clusters. Importantly, the different slopes and intercepts obtained from the Geiger–Nuttall plots of log10(T 1/2) vs. Q −1/2 confirming the presence of shell closure effect and the plot of universal curve of log10(T 1/2) vs.−lnP revealed the reliability of the model CPPM.

Numerical investigation of the effect of stagger on the aerodynamic characteristics of a Busemann biplane

Busemann biplanes and its modified versions are recently being reinvestigated for possible low boom supersonic transport. The Busemann biplane offers a very favorable drag reduction at design supersonic Mach numbers due to wave cancellation effect. However, at the off design speeds its performance deteriorates and the wave cancellation effect offer no favorable drag reductions. Another problem associated with the Busemann biplane is the chocking of the flow due to inability of the biplane to engulf the normal starting shock wave in front of the biplane. This paper attempts to address the chocking problem through the numerical simulation of Busemann biplane with staggered airfoil configurations. Lift and drag characteristics of a Busemann biplane with staggered tandem airfoil configurations are investigated at various Mach numbers between 0.5 and 2.5 using Computational Fluid Dynamics. The stagger increases the throat area thus reduces the flow chocking characteristics of the Busemann biplane without effecting the wave cancellation much. The results suggest that a significant reduction in wave drag can be realized even at off-design conditions, especially at low Mach numbers through staggering of the Busemann biplanes.

Effect of Stagger on the Vibroacoustic Loads from Clustered Rockets

The effect of stagger startup on the vibroacoustic loads that form during the end-effects regime of clustered rockets is studied using both full-scale (hot-gas) and laboratory-scale (cold-gas) data with vehicle geometry. Both configurations comprise three nozzles with thrust-optimized parabolic contours that undergo free-shock separated flow and restricted-shock separated flow as well as an end-effects regime before flowing full. Acoustic pressure waveforms recorded at the base of the nozzle cluster are analyzed using various statistical metrics as well as time-frequency analysis. The findings reveal a significant reduction in end-effects regime loads when engine startups are staggered. However, regardless of stagger, both the skewness and kurtosis of the acoustic pressure time derivative elevate to the same levels, thereby demonstrating the intermittence and impulsiveness of the acoustic waveforms during the end-effects regime.

Even-odd staggering of the spectroscopic factor as new evidence forαclustering

We evidence a staggering effect of the experimental spectroscopic factors corresponding to even-even and odd-mass (odd-mass and odd-odd) $\ensuremath{\alpha}$ emitters. The comparison to the theoretical estimate within the standard Bardeen-Cooper-Schrieffer (BCS) approach reveals a similar staggering, but with a different behavior. It turns out that the ratio between corresponding experimental and theoretical spectroscopic factors is proportional to the experimental reduced decay width. A similar dependence was found in a previous work between the strength of the quadrupole-quadrupole $\ensuremath{\alpha}$-core interaction, describing the $\ensuremath{\alpha}$-decay fine structure and the reduced width. Thus, the even-odd staggering effect in the spectroscopic factor is a new evidence of the $\ensuremath{\alpha}$-clustering phenomenon in medium and heavy nuclei.

Review of Stock Markets’ Reaction to New Events: Evidence from Brexit

Several studies have evolved to deal with the determinants of stock market volatility. However, there exists a gap in literature with regards to the interrelation among the broad categories of factors that trigger stock market reaction namely company fundaments, technical factors and market sentiments. This paper provides a holistic and comprehensive theoretical review of drivers of stock markets’ reaction as well as designs an interrelated conceptual framework of the factors that influence investors’ decision making to fill the gap in literature. Brexit is presented as a case study to illustrate how investors and stock markets are affected by new events or information. This study will reveal some of the global staggering effects of Brexit at the end of trading on June 24, 2016 in areas such as currencies, stock markets, banks, commodities, bonds, automakers and homebuilders as well as hedge fund. Barely 24 hours after the results of Brexit were declared; global stock markets lost about $2 trillion in value. The British pound plunged to almost $1.33, its lowest level in over 30 years against the US dollar and gold proved to be one of the few safe havens for investors on that day. In order for investors to insulate themselves against loses from Black Swans events, the conclusion of this study recommends some protective mechanisms for investors which include avoidance of overexposure and stockpiling of cash.

Isospin influence on the decay modes of the systems produced in the78,86Kr +40,48Ca reactions at 10 AMeV

The results of the analysis of the reactions 78,86Kr +40,48 Ca at 10 AMeV are presented. The experiment was performed at the INFN Laboratori Nazionali del Sud (LNS) in Catania by using the 4π multidetector CHIMERA, with beams delivered by the Superconductive Cyclotron. The competition among the various disintegration paths and in particular the isospin effects on the decay modes of the produced composite systems are investigated; this provides information about fundamental nuclear quantities such as level density, fission barrier and viscosity. Different isotopic composition and relative richness are observed among the reaction products of the two systems. An odd-even staggering effect is present in the charge distributions, in particular for the light fragments produced by the neutron-poor system. The kinematical characteristics of the IMF seem to indicate a high degree of the relaxation of the formed system. Besides, global features analysis seems to show some differences in the contribution arising from the various reaction mechanisms for the two reactions.

Methods for a quantitative evaluation of odd-even staggering effects

Odd-even effects, also known as "staggering" effects, are a common feature observed in the yield distributions of fragments produced in different types of nuclear reactions. We review old methods, and we propose new ones, for a quantitative estimation of these effects as a function of proton or neutron number of the reaction products. All methods are compared on the basis of Monte Carlo simulations. We find that some are not well suited for the task, the most reliable ones being those based either on a non-linear fit with a properly oscillating function or on a third (or fourth) finite difference approach. In any case, high statistic is of paramount importance to avoid that spurious structures appear just because of statistical fluctuations in the data and of strong correlations among the yields of neighboring fragments.

A method to calculate fission-fragment yields Y(Z,N) versus proton and neutron number in the Brownian shape-motion model

We propose a method to calculate the two-dimensional (2D) fission-fragment yield $Y(Z,N)$ versus both proton and neutron number, with inclusion of odd-even staggering effects in both variables. The approach is to use the Brownian shape-motion on a macroscopic-microscopic potential-energy surface which, for a particular compound system is calculated versus four shape variables: elongation (quadrupole moment Q2), neck d , left nascent fragment spheroidal deformation $ \epsilon_{f1}$ , right nascent fragment deformation $ \epsilon_{f2}$ and two asymmetry variables, namely proton and neutron numbers in each of the two fragments. The extension of previous models 1) introduces a method to calculate this generalized potential-energy function and 2) allows the correlated transfer of nucleon pairs in one step, in addition to sequential transfer. In the previous version the potential energy was calculated as a function of Z and N of the compound system and its shape, including the asymmetry of the shape. We outline here how to generalize the model from the “compound-system” model to a model where the emerging fragment proton and neutron numbers also enter, over and above the compound system composition.

Delta I = 1 staggering effect for negative parity rotational bands with K = 1/2 in W/Os/Pt odd-mass nuclei

The anomalous negative-parity bands of odd-mass nuclei W/Os/Pt for N = 103 isotones are studied within the framework of particle rotor model (PRM). The phenomenon of ΔI = 1 staggering or signature splitting in energies occurs as one plots the gamma transitional energy over spin (EGOS) versus spin for the 1/2-[521] band originating from N = 5 single particle orbital. The rotational band with K = 1/2 separates into two signature partners. The levels with I = 1/2, 5/2, 9/2,… are displaced relatively to the levels with I = 3/2,7/2,11/2,…. The deviations of the level energies from the rigid rotor values is described by Coriolis coupling.

Ab initioestimations of the isotope shift for the first three elements of the K isoelectronic sequence

Isotope shifts (ISs) of ${D}_{1}\phantom{\rule{4.pt}{0ex}}(ns\phantom{\rule{0.16em}{0ex}}^{2}S_{1/2}\ensuremath{\rightarrow}np\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2})$ and ${D}_{2}\phantom{\rule{4.pt}{0ex}}(ns\phantom{\rule{0.16em}{0ex}}^{2}S_{1/2}\ensuremath{\rightarrow}np\phantom{\rule{0.16em}{0ex}}^{2}P_{3/2})$ transitions for the first three elements of the K isoelectronic sequence are calculated with all-order correlated relativistic coupled-cluster theory. To get precise ab initio results, all the orbitals of the reference states have been optimized by a linear regression technique. Some of the important IS estimations reported here were not available in literature. Interesting features of odd-even staggering and magic neutron number effects are also observed in the case of volume shift calculations. Energy-level corrections for a few levels due to a change in the nuclear model from a point nucleus to a Fermi nucleus have been studied with interesting correlation features and compared with other theoretical results available in literature.

Influence of the density of states on the odd-even staggering in the charge distribution of the emitted fragments in nuclear heavy-ion collisions

The fragmentation of thermalized sources is studied using a version of the Statistical Multifragmentation Model which employs state densities that take the pairing gap in the nuclear levels into account. Attention is focused on the properties of the charge distributions observed in the breakup of the source. Since the microcanonical version of the model used in this study provides the primary fragment excitation energy distribution, one may correlate the reduction of the odd-even staggering in the charge distribution with the increasing occupation of high-energy states. Thus, in the framework of this model, such staggering tends to disappear as a function of the total excitation energy of the source, although the energy per particle may be small for large systems. We also find that, although the deexcitation of the primary fragments should, in principle, blur these odd-even effects as the fragments follow their decay chains, the consistent treatment of pairing may significantly enhance these staggering effects on the final yields. In the framework of this model, we find that odd-even effects in the charge distributions should be observed in the fragmentation of relatively light systems at very low excitation energies. Our results also suggest that the odd-even staggering may provide useful information on the nuclear state density.

A decade of data from a specialist statewide child and adolescent eating disorder service: does local service access correspond with the severity of medical and eating disorder symptoms at presentation?

BackgroundEating disorders affect up to 3% of children and adolescents, with recovery often requiring specialist treatment. A substantial literature has accrued suggesting that lower access to health care services, experienced by rural populations, has a staggering effect on health-related morbidity and mortality. The aim of this study was to evaluate whether lower service access foreshadowed a more severe medical and symptom presentation among children and adolescents presenting to a specialist eating disorders program.MethodThe data source was the Helping to Outline Paediatric Eating Disorders (HOPE) Project registry (N ~1000), a prospective ongoing registry study comprising consecutive paediatric tertiary eating disorder referrals. The sample consisted of 399 children and adolescents aged 8 to 16 years (M =14.49, 92% female) meeting criteria for a DSM-5 eating disorder.ResultsConsistent with the hypotheses, lower service access was associated with a lower body mass index z-score and a higher likelihood of medical complications at intake assessment. Contrary to our hypothesis, eating pathology assessed at intake was associated with higher service access. No relationship was observed between service access and duration of illness or percentage of body weight lost.ConclusionsLower service access is associated with more severe malnutrition and medical complications at referral to a specialist eating disorder program. These findings have implications for service planning and provision for rural communities to equalize health outcomes.

Isospin physics by CHIMERA detector

This contribution presents some recent results relative to the studies of isospin- asymmetric nuclear matter in experiments using the 4π detector CHIMERA and the beams delivered by the Superconductive Cyclotron at INFN-Laboratori Nazionali del Sud in Catania. In particular, we report the results of the experiments named "Reverse" and "Isodec", both included in the EXOCHIM activity supported by the CNSIII of INFN. In the Isodec experiment, the two systems 78Kr+40Ca (neutron poor) and 86Kr+48Ca (neutron rich) at 10A MeV were studied, looking at the competition between the various disintegration decay paths of medium mass compound nuclei, formed by fusion processes and at the isospin influence on the decay process. The results show the presence of a relaxed component in the reaction mechanism, the evidence of staggering effects in the Z distributions, as well as different isotopic composition and neutron enrichment for the reaction products in the two systems. In the Reverse experiment, mass asymmetric projectile-target combinations 124Sn+64Ni and 112Sn+58Ni were investigated at 35A MeV. We provide evidence that the Dynamical Fission process is about two times more probable than the equilibrated (statistical) Fission one in the neutron rich 124Sn+64Ni system with respect to the 112Sn+58Ni neutron poor one. The observed difference in the strength of the dynamical effects could arise from the difference in the entrance channel Isospin (N/Z) content.

Decay competition in IMF production in the collisions 78Kr+40Ca and 86Kr+48Ca at 10 AMeV

De-excitation modes of compound systems 118Ba and 134Ba' produced respectively in the 78Kr+40Ca and 86Kr+48Ca collisions at 10 A.MeV' are investigated. In particular' the competition between the various disintegration decay paths of medium mass compound nuclei' formed by fusion processes and the isospin (related to N/Z) of the entrance channel influence on the decay process' are studied. Data were taken at the INFN-Laboratori Nazionali del Sud (LNS) in ISODEC experiment' by using the CHIMERA array. The experiment complements and improves the previous experiment performed at GANIL where the same mechanisms were studied at lower excitation energies. The results show the presence of a relaxed component in the reaction mechanism' evident staggering effects in the Z distributions' as well as different isotopic composition and neutron enrichment for the reaction products in the two systems.

Axial–torsional vibrations of rotating pretwisted thin walled composite beams

Axial–torsional vibrations of rotating pretwisted thin-walled composite box beams exhibiting primary and secondary warping are investigated. Considering the nonlinear strain–displacement relations, the coupled nonlinear axial–torsional equations of motion are derived using Hamilton's principle. Ignoring the axial inertia term leads to differential equation of motion in terms of elastic torsion in the case of axially immovable beams. Centrifugal load in the presence of material anisotropy and pretwist angle leads to an induced static torque. The nonlinear equation should be linearized about the corresponding equilibrium state to obtain the linear differential equation of motion. Extended Galerkin's method is utilized to achieve the proper eigenvalue problem. The results obtained in this paper seek to clarify the individual and collective effects of axial loading, pretwist, stagger and fiber angles on the torsional behavior of the non-uniform thin-walled composite blades. The results are compared to available analytical and experimental results in the literature which reveals excellent agreements. The outcomes of this study are expected to offer better predictions of the dynamic behavior of this kind of structures in general, and in design of rotor blades of turbo-machinery, in particular.

A decade of data from a specialist statewide child and adolescent eating disorder service: does local service access correspond with the severity of medical and eating disorder symptoms at presentation?

BackgroundEating disorders affect up to 3% of children and adolescents, with recovery often requiring specialist treatment. A substantial literature has accrued suggesting that lower access to health care services, experienced by rural populations, has a staggering effect on health-related morbidity and mortality. The aim of this study was to evaluate whether lower service access foreshadowed a more severe medical and symptom presentation among children and adolescents presenting to a specialist eating disorders program.MethodThe data source was the Helping to Outline Paediatric Eating Disorders (HOPE) Project registry (N ~1000), a prospective ongoing registry study comprising consecutive paediatric tertiary eating disorder referrals. The sample consisted of 399 children and adolescents aged 8 to 16 years (M =14.49, 92% female) meeting criteria for a DSM-5 eating disorder.ResultsConsistent with the hypotheses, lower service access was associated with a lower body mass index z-score and a higher likelihood of medical complications at intake assessment. Contrary to our hypothesis, eating pathology assessed at intake was associated with higher service access. No relationship was observed between service access and duration of illness or percentage of body weight lost.ConclusionsLower service access is associated with more severe malnutrition and medical complications at referral to a specialist eating disorder program. These findings have implications for service planning and provision for rural communities to equalize health outcomes.