2,472 research outputs found
Sales Growth of New Pharmaceuticals Across the Globe: The Role of Regulatory Regimes
Prior marketing literature has overlooked the role of regulatory regimes in explaining international sales growth of new products. This paper addresses this gap in the context of new pharmaceuticals (15 new molecules in 34 countries) and sheds light on the effect regulatory regimes have on new drug sales across the globe. Based on a time-varying coefficient model, we find that differences in regulation substantially contribute to cross-country variation in sales. One of the regulatory constraints investigated, i.e. manufacturer price controls, has a positive effect on drug sales. The other forms of regulation such as restrictions of physician prescription budgets and the prohibition of direct-to-consumer advertising tend to hurt sales. The effect of manufacturer price controls is similar for newly launched and mature drugs. In contrast, regulations on physician prescription budget and direct-to-consumer advertising have a differential effect for newly launched and mature drugs. While the former hurts mature drugs more, the latter has a larger effect on newly launched drugs. In addition to these regulatory effects, we find that national culture, economic wealth, introduction timing, lagged sales and competition, also affect drug sales. Our findings may be used as input by managers for international launch and sales decisions. They may also be used by public policy administrators to compare drug sales in their country to other countries and to assess the role of regulatory regimes therein.economics;regulation;culture;drug;international new product growth;penalized splines;pharmaceutical;timevarying effects
On The Predictive Content Of Production Surveys: A Pan-European Study
For over forty years, Business Tendency Surveys have been collected in multiple member states of the European Union. Previous research has studied the predictive accuracy of the expectation variables included in those surveys through bivariate, within-country, Granger-causality tests, which has resulted in mixed conclusions. We extend previous research in various ways, as we (i) explicitly allow for cross-country influences, and (ii) do so using both bivariate and multivariate Granger-causality tests. Specifically, the multivariate El-Himdi and Roy test is adapted to jointly test the forecasting value of multiple production expectation series, to assess whether part of this joint effect is indeed due to cross-country influences, and to determine which countries' expectation series have most "clout" in predicting the production levels in the other member countries, or have higher "receptivity", in that their production levels are Granger-caused by the other countries' expectations.business surveys;cross-correlations;granger causality;production expectations
Modeling Within- and Across-Customer Association in Lifetime Value with Copulas
Recent advances in linking Recency-Frequency-Monetary value (RFM) data to Customer Lifetime Value (CLV) in non-contractual settings rely on the assumption of independence between the transaction and spend processes. We propose to model jointly the inter- and intra-customer dependency between both processes using copulas, hereby accounting for the double correlation within and across customers. Applied to a unique data set of securities' transactions, we nd that modeling both associations enhances the accuracy of CLV predictions, thus improving customer valuation and selection tasks.Association;Copula;Customer Lifetime Value;Across and Within Customers
Low Energy Singlets in the Excitation Spectrum of the Spin Tetrahedra System Cu_2Te_2O_5Br_2
Low energy Raman scattering of the s=1/2 spin tetrahedra system
Cu_2Te_2O_5Br_2 is dominated by an excitation at 18 cm^{-1} corresponding to an
energy E_S=0.6\Delta, with \Delta the spin gap of the compound. For elevated
temperatures this mode shows a soft mode-like decrease in energy pointing to an
instability of the system. The isostructural reference system Cu_2Te_2O_5Cl_2
with a presumably larger inter-tetrahedra coupling does not show such a low
energy mode. Instead its excitation spectrum and thermodynamic properties are
compatible with long range Neel-ordering. We discuss the observed effects in
the context of quantum fluctuations and competing ground states.Comment: 5 pages, 2 figures, ISSP-Kashiwa 2001, Conference on Correlated
Electron
Relation between Kitaev magnetism and structure in -RuCl
Raman scattering has been employed to investigate lattice and magnetic
excitations of the honeycomb Kitaev material -RuCl and its
Heisenberg counterpart CrCl. Our phonon Raman spectra give evidence for a
first-order structural transition from a monoclinic to a rhombohedral structure
for both compounds. Significantly, only -RuCl features a large
thermal hysteresis, consistent with the formation of a wide phase of
coexistence. In the related temperature interval of K, we observe a
hysteretic behavior of magnetic excitations as well. The stronger magnetic
response in the rhombohedral compared to the monoclinic phase evidences a
coupling between the crystallographic structure and low-energy magnetic
response. Our results demonstrate that the Kitaev magnetism concomitant with
fractionalized excitations is susceptible to small variations of bonding
geometry.Comment: 9 pages, 8 figures, To appear in PR
Dynamical Dzyaloshinsky-Moriya interaction in KCuF3: Raman evidence for an antiferrodistortive lattice instability
In the orbitally ordered, quasi-one dimensional Heisenberg antiferromagnet
KCuF3 the low-energy Eg and B1g phonon modes show an anomalous softening (25%
and 13%) between room temperature and the characteristic temperature T_S = 50
K. In this temperature range a freezing-in of F ion dynamic displacements is
proposed to occur. In addition, the Eg mode at about 260 cm-1 clearly splits
below T_S. The width of the phonon lines above T_S follows an activated
behavior with an activation energy of about 50 K. Our observations clearly
evidence a reduction of the structural symmetry below T_S and indicate a strong
coupling of lattice and spin fluctuations for T>T_S.Comment: 7 pages, 9 figure
Positive contraction mappings for classical and quantum Schrodinger systems
The classical Schrodinger bridge seeks the most likely probability law for a
diffusion process, in path space, that matches marginals at two end points in
time; the likelihood is quantified by the relative entropy between the sought
law and a prior, and the law dictates a controlled path that abides by the
specified marginals. Schrodinger proved that the optimal steering of the
density between the two end points is effected by a multiplicative functional
transformation of the prior; this transformation represents an automorphism on
the space of probability measures and has since been studied by Fortet,
Beurling and others. A similar question can be raised for processes evolving in
a discrete time and space as well as for processes defined over non-commutative
probability spaces. The present paper builds on earlier work by Pavon and
Ticozzi and begins with the problem of steering a Markov chain between given
marginals. Our approach is based on the Hilbert metric and leads to an
alternative proof which, however, is constructive. More specifically, we show
that the solution to the Schrodinger bridge is provided by the fixed point of a
contractive map. We approach in a similar manner the steering of a quantum
system across a quantum channel. We are able to establish existence of quantum
transitions that are multiplicative functional transformations of a given Kraus
map, but only for the case of uniform marginals. As in the Markov chain case,
and for uniform density matrices, the solution of the quantum bridge can be
constructed from the fixed point of a certain contractive map. For arbitrary
marginal densities, extensive numerical simulations indicate that iteration of
a similar map leads to fixed points from which we can construct a quantum
bridge. For this general case, however, a proof of convergence remains elusive.Comment: 27 page
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