Schwarzschild and Synge once again

We complete the historical overview about the geometry of a Schwarzschild black hole at its horizon by emphasizing the contribution made by J. L. Synge in 1950 to its clarification.Comment: 2 pages, LaTeX, submitted for publication; 2 references, one Note, and an Acknowledgement are adde

Care coordination in a business-to-business and a business-to-consumer model for telemonitoring patients with chronic diseases

__Introduction:__ For telemonitoring to support care coordination, a sound business model is conditional. The aim of this study is to explore the systemic and economic differences in care coordination via business-to-business and business-to-consumer models for telemonitoring patients with chronic diseases. __Methods:__ We performed a literature search in order to design the business-to-business and business-to-consumer telemonitoring models, and to assess the design elements and themes by applying the activity system theory, and describe the transaction costs in each model. The design elements are content, structure, and governance, while the design themes are novelty, lock-in, complementarities, and efficiency. In the transaction cost analysis, we looked into all the elements of a transaction in both models. __Results:__ Care coordination in the business-to-business model is designed to be organized between the places of activity, rather than the participants in the activity. The design of the business-to-business model creates a firm lock-in but for a limited time. In the business-to-consumer model, the interdependencies are to be found between the persons in the care process and not between the places of care. The differences between the models were found in both the design elements and the design themes. __Discussion:__ Care coordination in the business-to-business and business-to-consumer models for telemonitoring chronic diseases differs in principle in terms of design elements and design themes. Based on the theoretical models, the transaction costs could potentially be lower in the business-to-consumer model than in the business-to-business, which could be a promoting economic principle for the implementation of telemonitoring

Assessment of a Business-to-Consumer (B2C) model for Telemonitoring patients with Chronic Heart Failure (CHF)

Background: The purpose of this study is to assess the Business-to-Consumer (B2C) model for telemonitoring patients with Chronic Heart Failure (CHF) by analysing the value it creates, both for organizations or ventures that provide telemonitoring services based on it, and for society. Methods: The business model assessment was based on the following categories: caveats, venture type, six-factor alignment, strategic market assessment, financial viability, valuation analysis, sustainability, societal impact, and technology assessment. The venture valuation was performed for three jurisdictions (countries) - Singapore, the Netherlands and the United States - in order to show the opportunities in a small, medium-sized, and large country (i.e. population). Results: The business model assessment revealed that B2C telemonitoring is viable and profitable in the Innovating in Healthcare Framework. Analysis of the ecosystem revealed an average-to-excellent fit with the six factors. The structure and financing fit was average, public policy and technology alignment was good, while consumer alignment and accountability fit was deemed excellent. The financial prognosis revealed that the venture is viable and profitable in Singapore and the Netherlands but not in the United States due to relatively high salary inputs. Conclusions: The B2C model in telemonitoring CHF potentially creates value for patients, shareholders of the service provider, and society. However, the validity of the results could be improved, for instance by using a peer-reviewed framework, a systematic literature search, case-based cost/efficiency inputs, and varied scenario inputs

Generation of Porous Particle Structures using the Void Expansion Method

The newly developed "void expansion method" allows for an efficient generation of porous packings of spherical particles over a wide range of volume fractions using the discrete element method. Particles are randomly placed under addition of much smaller "void-particles". Then, the void-particle radius is increased repeatedly, thereby rearranging the structural particles until formation of a dense particle packing. The structural particles' mean coordination number was used to characterize the evolving microstructures. At some void radius, a transition from an initially low to a higher mean coordination number is found, which was used to characterize the influence of the various simulation parameters. For structural and void-particle stiffnesses of the same order of magnitude, the transition is found at constant total volume fraction slightly below the random close packing limit. For decreasing void-particle stiffness the transition is shifted towards a smaller void-particle radius and becomes smoother.Comment: 9 pages, 8 figure

Quantifying environmental heterogenety: habitat size necessary for successful development of cod Gadus morhua eggs in the Baltic Sea

Spatial and temporal variability in environmental factors can exert major influences on survival and growth of living organisms. However, in many key areas of fisheries science (e.g. growth, survival and recruitment determination), environmental heterogeneity is usually ignored because of insufficient environmental or fisheries data or lack of evidence that such heterogeneity impacts response variables. For the eastern Baltic Sea (ICES Subdivisions 25 to 32), we evaluated spatial and temporal differences in conditions affecting the survival of cod Gadus morhua L. eggs at survival on four distinct spawning sites within the assessment area. We intercalibrated ways of quantifying the volume of water ('reproductive volume') at each site where salinity, oxygen and temperature conditions permitted successful egg development. We have developed and compared a time series (1952 to 1996) of reproductive volumes among the areas to identify spatial differences. The results of 2 independent volume-estimation methods are comparable, indicating that highly significant differences exist among the sites, and that the westernmost spawning ground, Bornholm Basin, has on average the highest reproductive volume and the lowest variability among the 4 sites. These findings may be useful in evaluating how spatial and temporal variability in environmental conditions affect egg hatching success and possibly recruitment in the Baltic stock

Quantum Monte Carlo and variational approaches to the Holstein model

Based on the canonical Lang-Firsov transformation of the Hamiltonian we develop a very efficient quantum Monte Carlo algorithm for the Holstein model with one electron. Separation of the fermionic degrees of freedom by a reweighting of the probability distribution leads to a dramatic reduction in computational effort. A principal component representation of the phonon degrees of freedom allows to sample completely uncorrelated phonon configurations. The combination of these elements enables us to perform efficient simulations for a wide range of temperature, phonon frequency and electron-phonon coupling on clusters large enough to avoid finite-size effects. The algorithm is tested in one dimension and the data are compared with exact-diagonalization results and with existing work. Moreover, the ideas presented here can also be applied to the many-electron case. In the one-electron case considered here, the physics of the Holstein model can be described by a simple variational approach.Comment: 18 pages, 11 Figures, v2: one typo correcte

The Cost-Effectiveness Analysis of Philips Motiva Telehealth System

Objectives The clinical effectiveness of Motiva Monitor platform was established in the previous study (TEN-HMS). Patients randomly assigned to receive Usual Care had higher one year mortality (45%) than patients assigned to receive Nurse Telephone Support (27%) or Home Telemonitoring (29%) (p=0.032). Our intention is to provide insights in the cost-effectiveness of Motiva telehealth system by modeling the intervention and running the analysis on top of the reported data. Methods Effectiveness was established by mining the EuroQol-5D from the original database, while the information on costs came from the literature and the manufacturer of the equipment. Direct healthcare costs considered ER visits, GP, Specialist, Hospitalist and Nurse time and resources utilization. The induced (indirect) costs were not considered in the analysis. The approximation of the cost of medical consumption came from the Netherlands only, although the original study was run in three European countries. We assumed the payer perspective for our analysis. Results The results clearly show, within the parameters of our model, the increased effectiveness of Home Telemonitoring and Nurse Telephone Support in comparison to the Usual Care. The deterministic results show ICERs of € 14.842 and € 12.547 per QALY (discounted at 1.5% a year) for HTM and NTS respectfully. Probabilistic results show that NTS was the most effective strategy in health systems that pay more than €12.500 per QALY. In the subgroup analysis HTM dominated both NTS and UC at the threshold of €16.500 in NYHA IV group of Chronic Heart Failure patients. Conclusions Home telemonitoring by Motiva Monitor system reduces mortality and lowers the in-hospital length of stay. On the quality of life dimensions, Home Telemonitoring was similarly effective as the Nurse Telephone Support, but with more costs. The cost-effectiveness analysis shows that both NTS and HTM dominate the Usual Care at WTP of €15.000

Value of information analysis in telehealth for chronic heart failure management

Objectives Value of information (VOI) analysis provides information on opportunity cost of a decision in healthcare by estimating the cost of reducing parametric uncertainty and quantifying the value of generating additional evidence. This study is an application of the VOI methodology to the problem of choosing between home telemonitoring and nurse telephone support over usual care in chronic heart failure management in the Netherlands. Methods The expected value of perfect information (EVPI) and the expected value of partially perfect information (EVPPI) analyses were based on an informal threshold of €20K per quality-adjusted life-year. These VOI-analyses were applied to a probabilistic Markov model comparing the 20-year costs and effects in three interventions. The EVPPI explored the value of decision uncertainty caused by the following group of parameters: treatment-specific transition probabilities between New York Heart Association (NYHA) defined disease states, utilities associated with the disease states, number of hospitalizations and ER visits, health state specific costs, and the distribution of patients per NYHA group. We performed the analysis for two population sizes in the Netherlands—patients in all NYHA classes of severity, and patients in NYHA IV class only. Results The population EVPI for an effective population of 2,841,567 CHF patients in All NYHA classes of severity over the next 20 years is more than €4.5B, implying that further research is highly cost-effective. In the NYHA IV only analysis, for the effective population of 208,003 patients over next 20 years, the population EVPI at the same informal threshold is approx. €590M. The EVPPI analysis showed that the only relevant group of parameters that contribute to the overall decision uncertainty are transition probabilities, in both All NYHA and NYHA IV analyses. Conclusions Results of our VOI exercise show that the cost of uncertainty regarding the decision on reimbursement of telehealth interventions for chronic heart failure patients is high in the Netherlands, and that future research is needed, mainly on the transition probabilities

Stokes-operator-squeezed continuous-variable polarization states

We investigate nonclassical Stokes-operator variances in continuous-wave polarization-squeezed laser light generated from one and two optical parametric amplifiers. A general expression of how Stokes-operator variances decompose into two-mode quadrature operator variances is given. Stokes parameter variance spectra for four different polarization-squeezed states have been measured and compared with a coherent state. Our measurement results are visualized by three-dimensional Stokes-operator noise volumes mapped on the quantum Poincare sphere. We quantitatively compare the channel capacity of the different continuous-variable polarization states for communication protocols. It is shown that squeezed polarization states provide 33% higher channel capacities than the optimum coherent beam protocol