A generalized Tullock contest

We construct a generalized Tullock contest under complete information where contingent upon winning or losing, the payoff of a player is a linear function of prizes, own effort, and the effort of the rival. This structure nests a number of existing contests in the literature and can be used to analyze new types of contests. We characterize the unique symmetric equilibrium and show that small parameter modifications may lead to substantially different types of contests and hence different equilibrium effort levels

Connection between effective-range expansion and nuclear vertex constant or asymptotic normalization coefficient

Explicit relations between the effective-range expansion and the nuclear vertex constant or asymptotic normalization coefficient (ANC) for the virtual decay $B\to A+a$ are derived for an arbitrary orbital momentum together with the corresponding location condition for the ($A+a$) bound-state energy. They are valid both for the charged case and for the neutral case. Combining these relations with the standard effective-range function up to order six makes it possible to reduce to two the number of free effective-range parameters if an ANC value is known from experiment. Values for the scattering length, effective range, and form parameter are determined in this way for the $^{16}$O+$p$, $\alpha+t$ and $\alpha+^3$He collisions in partial waves where a bound state exists by using available ANCs deduced from experiments. The resulting effective-range expansions for these collisions are valid up to energies larger 5 MeV.Comment: 17 pages, 6 figure

Microscopic description of the beta delayed deuteron emission from \bbox{^6}He

The beta delayed deuteron emission from $^6$He is studied in a dynamical microscopic cluster model. This model gives a reasonably good description for all the subsystems of $^6$He and $^6$Li in a coherent way, without any free parameter. The beta decay transition probability to the $^6$Li ground state is underestimated by a few percents. The theoretical beta delayed deuteron spectrum is close to experiment but it is also underestimated by about a factor 1.7. We argue that, in spite of their different magnitudes, both underestimations might have a common origin. The model confirms that the neutron halo part of the $^6$He wave function plays a crucial role in quenching the beta decay toward the $\alpha$ + d channel.Comment: LATEX with REVTEX, Submitted to Phys. Rev. C, 11 pages, 3 figures (not included) are available upon request. ATOMKI-93/

Supersymmetric transformations for coupled channels with threshold differences

The asymptotic behaviour of the superpotential of general SUSY transformations for a coupled-channel Hamiltonian with different thresholds is analyzed. It is shown that asymptotically the superpotential can tend to a diagonal matrix with an arbitrary number of positive and negative entries depending on the choice of the factorization solution. The transformation of the Jost matrix is generalized to "non-conservative" SUSY transformations introduced in Sparenberg et al (2006 J. Phys. A: Math. Gen. 39 L639). Applied to the zero initial potential the method permits to construct superpartners with a nontrivially coupled Jost-matrix. Illustrations are given for two- and three-channel cases.Comment: 17 pages, 3 explicit examples and figures adde

Coulomb corrected eikonal description of the breakup of halo nuclei

The eikonal description of breakup reactions diverges because of the Coulomb interaction between the projectile and the target. This divergence is due to the adiabatic, or sudden, approximation usually made, which is incompatible with the infinite range of the Coulomb interaction. A correction for this divergence is analysed by comparison with the Dynamical Eikonal Approximation, which is derived without the adiabatic approximation. The correction consists in replacing the first-order term of the eikonal Coulomb phase by the first-order of the perturbation theory. This allows taking into account both nuclear and Coulomb interactions on the same footing within the computationally efficient eikonal model. Excellent results are found for the dissociation of 11Be on lead at 69 MeV/nucleon. This Coulomb Corrected Eikonal approximation provides a competitive alternative to more elaborate reaction models for investigating breakup of three-body projectiles at intermediate and high energies.Comment: 19 pages, 9 figures, accepted for publication in Phys. Rev.

Eigenphase preserving two-channel SUSY transformations

We propose a new kind of supersymmetric (SUSY) transformation in the case of the two-channel scattering problem with equal thresholds, for partial waves of the same parity. This two-fold transformation is based on two imaginary factorization energies with opposite signs and with mutually conjugated factorization solutions. We call it an eigenphase preserving SUSY transformation as it relates two Hamiltonians, the scattering matrices of which have identical eigenphase shifts. In contrast to known phase-equivalent transformations, the mixing parameter is modified by the eigenphase preserving transformation.Comment: 16 pages, 1 figur

Addressing malnutrition in low- and middle-income countries with double-duty actions

Multiple forms of malnutrition co-exist (the double burden) in low- and middle-income countries, but most interventions and policies target only one form. Identifying shared drivers of the double burden of malnutrition is a first step towards establishing effective interventions that simultaneously address the double burden of malnutrition (known as double-duty actions). We identified shared drivers for the double burden of malnutrition, to assess which double-duty actions are likely to have the greatest reach in preventing all forms of malnutrition, in the context of the sustainable development goals. We reviewed existing conceptual frameworks of the drivers of undernutrition, obesity and environmental sustainability. Shared drivers affecting all forms of malnutrition and environmental sustainability were captured using a socio-ecological approach. The extent to which drivers were addressed by the five double-duty actions proposed by the WHO was assessed. Overall, eighty-three shared drivers for the double burden of malnutrition were identified. A substantial proportion (75·0%) could be addressed by the five WHO double-duty actions. ‘Regulations on marketing’ and ‘promotion of appropriate early and complementary feeding in infants’ addressed the highest proportion of shared drivers (65·1% and 53·0%, respectively). Twenty-four drivers were likely to be sensitive to environmental sustainability, with ‘regulations on marketing’ and ‘school food programmes and policies’ likely to have the greatest environmental reach. A quarter of the shared drivers remained unaddressed by the five WHO double-duty actions. Substantially more drivers could be addressed with minor modifications to the WHO double-duty actions and the addition of de novo actions

Protein C Activity in Dogs: Adaptation of a Commercial Human Colorimetric Assay and Evaluation of Effects of Storage Time and Temperature

Objectives of this study were to adapt a commercial human protein C (PC) colorimetric assay for use in dogs and to investigate effects of various storage conditions. The human assay was modified by using pooled canine plasma for calibration and by increasing the activation time. PC activity was measured in fresh canine plasma and in plasma stored under various conditions. PC activity of some stored samples was significantly different from that of fresh plasma; however, differences were small. No difference was detected in samples stored under similar conditions but analyzed in different laboratories using similar methodology. Results of this study indicate that the human colorimetric assay is suitable for canine samples if pooled canine plasma is used for calibration, that Clinical and Laboratory Standards Institute sample storage guidelines developed for testing in humans are appropriate for dogs, and that comparisons of results from laboratories using similar methodology are legitimate

Variational collocation for systems of coupled anharmonic oscillators

We have applied a collocation approach to obtain the numerical solution to the stationary Schr\"odinger equation for systems of coupled oscillators. The dependence of the discretized Hamiltonian on scale and angle parameters is exploited to obtain optimal convergence to the exact results. A careful comparison with results taken from the literature is performed, showing the advantages of the present approach.Comment: 14 pages, 10 table

Asymptotic normalization coefficients for mirror virtual nucleon decays in a microscopic cluster model

It has been suggested recently (Phys. Rev. Lett. 91, 232501 (2003)) that charge symmetry of nucleon-nucleon interactions relates the Asymptotic Normalization Coefficients (ANCs) of proton and neutron virtual decays of mirror nuclei. This relation is given by a simple analytical formula which involves proton and neutron separation energies, charges of residual nuclei and the range of their strong interaction with the last nucleon. Relation between mirror ANCs, if understood properly, can be used to predict astrophysically relevant direct proton capture cross sections using neutron ANCs measured with stable beams. In this work, we calculate one-nucleon ANCs for several light mirror pairs, using microscopic two-, three- and four-cluster models, and compare the ratio of mirror ANCs to the predictions of the simple analytic formula. We also investigate mirror symmetry between other characteristics of mirror one-nucleon overlap integrals, namely, spectroscopic factors and single-particle ANCs.Comment: 12 pages, submitted to Phys. Rev.