Patterns of stent purchasing in a collaborative procurement organisation

Leveraging purchasing power through collaborative purchasing arrangements is widely used to deliver efficiency savings in public procurement. The success of such arrangements requires the purchasing behaviours of individual members of the collaborative organisation to change in order to realise the benefits of lower prices. However the actual purchasing behaviours of organisations within a collaborative purchasing arrangement have not been widely researched. The research uses a stationary stochastic model of buyer behaviour, the NBDDirichlet, to describe and predict the purchasing behaviours of buyers of coronary and ureteral stents in a collaborative purchasing organisation in the English National Health Service. The three year analysis period is a period of major change for each category, the result of supplier promotional activity in the ureteral stent case and purchasing management activity in the case of the coronary stents. Deviations between the observed patterns of behaviour and the model predictions point to violations of the basic Dirichlet requirements of stationary markets and lack of partitioning. In both the ureteral and coronary stent cases the research identifies a segment of frequent purchasers whose behaviour differs from the rest of the population. The impact of framework agreements in restricting the purchasing repertoire of buyers is also identified as a deviation from typical purchasing patterns. Both interventions result in changes to established loyalty patterns, whereby the initial high observed levels of loyalty towards particular suppliers are replaced by a greater willingness to purchase from alternative suppliers. The data analysis also provides preliminary evidence for purchase deceleration as buyers defer purchases during a negotiation period in anticipation of improved pricing

On the neutron radiative capture in the vicinity of the giant dipole resonance

A semimicroscopical approach is applied for describing partial photonucleon reactions accompanying the excitation of the giant dipole resonance (GDR). The approach is based on continuum-RPA and the phenomenological description of doorway-state coupling to many-quasiparticle configurations. Apart from the phenomenological mean field, the separable isovector momentum-dependent forces are taken into consideration together with the momentum-independent Landau-Migdal interaction. It allows us to describe satisfactorily the experimental values of the GDR energy and the photoabsorption cross section integrated over the GDR in Pb-208 along with some partial Pb-208(n,gamma)-reaction cross sections in the vicinity of the GDR. An attempt to establish a correspondence between the approach and the well-known DSD-model was also undertaken. (C) 2000 Elsevier Science B.V. All rights reserved

Neutrinoless double beta decay in seesaw models

We study the general phenomenology of neutrinoless double beta decay in seesaw models. In particular, we focus on the dependence of the neutrinoless double beta decay rate on the mass of the extra states introduced to account for the Majorana masses of light neutrinos. For this purpose, we compute the nuclear matrix elements as functions of the mass of the mediating fermions and estimate the associated uncertainties. We then discuss what can be inferred on the seesaw model parameters in the different mass regimes and clarify how the contribution of the light neutrinos should always be taken into account when deriving bounds on the extra parameters. Conversely, the extra states can also have a significant impact, cancelling the Standard Model neutrino contribution for masses lighter than the nuclear scale and leading to vanishing neutrinoless double beta decay amplitudes even if neutrinos are Majorana particles. We also discuss how seesaw models could reconcile large rates of neutrinoless double beta decay with more stringent cosmological bounds on neutrino masses.Comment: 34 pages, 5 eps figures and 1 axodraw figure. Final version published in JHEP. NME results available in Appendi

Promoting Functional Health in Midlife and Old Age: Long-Term Protective Effects of Control Beliefs, Social Support, and Physical Exercise

Previous studies have examined physical risk factors in relation to functional health, but less work has focused on the protective role of psychological and social factors. We examined the individual and joint protective contribution of control beliefs, social support and physical exercise to changes in functional health, beyond the influence of health status and physical risk factors in middle-aged and older adults. Given that functional health typically declines throughout adulthood, it is important to identify modifiable factors that can be implemented to maintain functioning, improve quality of life, and reduce disability.We conducted a national longitudinal study, Midlife in the United States (MIDUS), with assessments in 1995-1996 and 2004-2006, and 3,626 community-residing adults, aged 32 to 84, were included in the analyses. Functional health (Physical Functioning subscale of the SF-36) and protective factors were measured at both occasions. While controlling for socio-demographic, health status, and physical risk factors (large waist circumference, smoking, and alcohol or drug problems), a composite of the three protective variables (control beliefs, social support, and physical exercise) at Time 1 was significantly related to functional health change. The more of these factors at Time 1, the better the health maintenance over 10 years. Among middle-aged and older adults, declines in health were significantly reduced with an increased number of protective factors.Age-related declines in health were reduced among those with more protective factors up to a decade earlier in life. Modifiable psychological, social, and physical protective factors, individually and in the aggregate, are associated with maintenance of functional health, beyond the damaging effects of physical risk factors. The results are encouraging for the prospect of developing interventions to promote functional health and for reducing public health expenditures for physical disability in later life

Abnormal Wnt and PI3Kinase Signaling in the Malformed Intestine of lama5 Deficient Mice

Laminins are major constituents of basement membranes and are essential for tissue homeostasis. Laminin-511 is highly expressed in the intestine and its absence causes severe malformation of the intestine and embryonic lethality. To understand the mechanistic role of laminin-511 in tissue homeostasis, we used RNA profiling of embryonic intestinal tissue of lama5 knockout mice and identified a lama5 specific gene expression signature. By combining cell culture experiments with mediated knockdown approaches, we provide a mechanistic link between laminin α5 gene deficiency and the physiological phenotype. We show that laminin α5 plays a crucial role in both epithelial and mesenchymal cell behavior by inhibiting Wnt and activating PI3K signaling. We conclude that conflicting signals are elicited in the absence of lama5, which alter cell adhesion, migration as well as epithelial and muscle differentiation. Conversely, adhesion to laminin-511 may serve as a potent regulator of known interconnected PI3K/Akt and Wnt signaling pathways. Thus deregulated adhesion to laminin-511 may be instrumental in diseases such as human pathologies of the gut where laminin-511 is abnormally expressed as it is shown here

E1 transitions between spin-dipole and Gamow-Teller giant resonances

The branching ratios for E1 transitions between the spin-dipole (SD) and Gamow-Teller (GT) giant resonances in Nb-90 and Pb-208 are evaluated. Assuming the main GT state has a wave function close to that for the "ideal" GT state, we reduced the problem to calculate the SD and GT strength functions. These strength functions are evaluated within an extended continuum-random phase approximation approach