Two-sided Model Research Articles

Quality measures for colonoscopy: where should we be in 2015?

Colonoscopy is an effective colorectal cancer (CRC) screening and prevention modality as evidenced by a 30-year decline in both incident colon cancers and CRC mortality in the USA. The USA is unique among the developed countries in its use of colonoscopy as the most common method to screen for CRC. Individual patients gain maximum value from their colonoscopy experience when they undergo a comfortable exam that is of highest quality, during which all polyps are found and removed safely and completely, where their physicians adhere to all appropriate guidelines and when they (or their insurance) pay a reasonable amount for their care. Colonoscopy "quality" publications to date have been focused on how to improve the individual physician's procedural results and this narrow focus has birthed an entire industry (usually based on entering data into a national registry) that is focused on demonstrating a physician's success in achieving a certain threshold performance metric that is usually (a) marginally related to true health outcomes, (b) can be captured from the myriad electronic medical records (EMR) in existence today, and (c) is attainable by most practicing gastroenterologists. Medical societies have worked diligently to link these registries and recognition programs to commercial or federal payer-based incentive funds. As health care reform drives massive consolidation of delivery systems and reimbursement moves toward population-level two-sided financial risk models, our current measurement infrastructure will become irrelevant. The focus on "value" and the Triple Aim will drive development of a radically different approach. The process by which individual gastroenterologists (or practices) demonstrate the value of colonoscopy as a colorectal cancer (CRC) prevention tool will change dramatically. Essentially, six measures will be reported by a health system: (1) percent of eligible population screened, (2) access to colonoscopy services, (3) complication rates, (4) patient experience scores, (5) episode (bundle) cost, and (6) frequency with which interval cancers occur after a colonoscopy exam (likely using a 3-year interval). Each gastroenterologist within a health system will be evaluated using familiar metrics (cecal intubation, withdrawal time, adenoma detection rate) but these results will likely be used internally to determine whether they are included in a provider network. If they continue to be used in commercial or government incentive programs, then the enterprise electronic medical record will be constructed to populate external programs directly. Population-level metrics (listed above) will determine whether higher cost provider networks (including academic health centers) who might deliver better health outcomes can compete successfully for regional market share with lower cost providers. This article will outline a plan for a health system initiative focused on provision of colonoscopy for CRC prevention; a plan that will help a group of gastroenterologists (whether employed within a health system or independent) demonstrate why they should be a preferred provider and whether they will survive and thrive in the coming world of accountable care.

Two-sided Internet platforms: A business model lifecycle perspective

Multi-sided platforms bring together two or more distinct but interdependent groups of customers, normally described as B2B and B2C. Two-sided platforms have proliferated rapidly with the Internet and this has led to the development of new business models to monetize innovative value propositions in online markets. This paper puts forward a model of the evolution of the marketing strategies and business models of two-sided Internet businesses. In this model, Internet intermediaries are visualized as resource integrators, involving consumers and business partners in a process of co-creation of value—an integrated, two-sided business model. An analysis of five early stage Internet ventures reveals that the business models of these Internet ventures show a clear pattern of evolution from inception to maturity, from B2C towards B2B, and ultimately to an integrated combination (B2B&C and B2C&B). This is primarily due to a shift in the relative influence of different business stakeholders, identified as change agents in the context of the business modeling of two-sided Internet platforms.

The Impact of Within Platform Competition in Two-Sided Business Models

We analyze theoretically and empirically the impact of exogenous changes in competition in one side of a two-sided market on the optimal pricing of both sides. We consider both its positive impact through enhanced indirect network externalities and its negative impact on same side agents because of higher competitive pressures. We find that unambiguously within platform competition causes an increase in the price charged to the other side of the market while its impact on same side is ambiguous. We test our hypothesis in the context of the U.S. airport industry exploiting an exogenous change in competition driven by a regulatory change. Consistent with our hypotheses, we estimate that an increase of within airport airline competition increases commercial revenues per passenger. This increase only takes place in airports that adopt a platform business model. We also investigate the impact of passengers through with both sides of the airport are connected.

移动产业双边市场的商业模式研究—以苹果公司为例

移动终端市场增长迅速，可观的市场前景为全球移动产业提供了巨大的利润和发展的空间。国内企业如何在社会转型的时代背景下建立创新的商业模式，该问题具有重要的理论及实践意义。苹果公司所建立的商业模式值得研究与学习。本文围绕商业模式的问题，基于对苹果公司案例分析，对移动产业生态圈需要建立的“双边市场”商业模式理论进行了详细阐述，并为中国移动产业未来发展提供了理论启示和发展建议。 The demand for mobile devices and intelligent terminals has increased hugely in recent years, which creates a great mobile market. In this background, Chinese companies need to know how to build the innovative business model to seize the opportunity. And it is worth researching the case of Apple Inc., which achieves great commercial success in this industry. Based on case study from Apple Inc. and research on mobile industry ecosystems, this paper illustrates the two-sided market model that Chinese enterprises in mobile industry have to build, and also gives the theoretical implications and development advices.

Uncertainty and Investment: The Financial Intermediary Balance Sheet Channel

Rollover risk imposes market discipline on banks’ risk-taking behavior but it can be socially costly. I present a two-sided model in which a bank simultaneously lends to a firm and borrows from the short-term funding market. When the bank is capital constrained, uncertainty in asset quality and rollover risk create a negative externality that spills over to the real economy by ex ante credit contraction. Macroprudential and monetary policies can be used to reduce the social cost of market discipline and improve efficiency.

Uncertainty and Investment: The Financial Intermediary Balance Sheet Channel

Rollover risk imposes market discipline on banks’ risk-taking behavior but it can be socially costly. I present a two-sided model in which a bank simultaneously lends to a firm and borrows from the short-term funding market. When the bank is capital constrained, uncertainty in asset quality and rollover risk create a negative externality that spills over to the real economy by ex ante credit contraction. Macroprudential and monetary policies can be used to reduce the social cost of market discipline and improve efficiency.

The temperature and pressure jumps at the vapor–liquid interface: Application to a two-phase cooling system

The temperature and pressure jump boundary conditions at the liquid–vapor interfaces, obtained from the kinetic theory, are implemented for the numerical simulation of two-surfaces problem of evaporation and condensation. For a small temperature difference between two interfaces the system of the Navier–Stokes equations (NS) together with the energy conservation equation and the linear approximation of these equations with the same jump boundary conditions are considered in the vapor phase. The numerical and analytical solutions are compared with that obtained previously from the linearized kinetic equation. The analytical temperature profiles derived from the both linearized systems are very close to each other, while the temperature distribution obtained from the full NS and energy equations has an absolutely different character. The velocity and pressure in the vapor phase are found to be constant, though the full NS and energy equations solution gives abrupt change of velocity near the condensation interface. The inverse temperature gradient phenomenon occurs for the considered small temperature difference. The solution in the vapor phase is then applied to a coupled two-phase system problem, which can be realized in a heat-transfer device combining the principles of both thermal conductivity and phase transition. The coupled two-sided (liquid and vapor) model with jump boundary conditions proposed here allows us to estimate the values of the evaporative mass flux and the heat flux, which can be removed from a heat source.

Binary Power Allocation in Symmetric Wyner-Type Interference Networks

The Wyner interference network is a popular model used in research on cellular networks due to its simplicity and analytical tractability. In this paper, the optimal power allocation strategies in symmetric one- and two-sided Wyner models are investigated. We determine a sufficient condition for binary power control (BPC) to be optimal that can be applied to the one-sided symmetric model. We consider binary power schemes for the symmetric two-sided Wyner network. Using a method of grouping links and performing a piecewise comparison of the group rates, we are able to determine the optimal power policy that maximizes the network sum rate. The result of the optimization can be expressed as follows for both types of networks: When the interfering channel gain √ϵ is small, it is optimal (in the class of binary schemes) to have all links on; otherwise, alternate links are switched off to remove interference. We characterize the critical values of ϵ where the transitions occur.

Welfare Effects of Paid for Prioritization Services: A Matching Model with Non-Uniform Quality of Service

We develop a stylized two-sided model of the local broadband Internet market where prices are used to facilitate “interactions” between the Broadband Internet Service Provider’s (BISP) subscribers and Content and Application Service Providers (CASPS), as well as the priority (i.e., speed) of those interactions. The model is used to evaluate the welfare and distributional effects of several “paid for prioritization” services offered by a BISP. The evaluation is conducted across a variety of economic environments to test the robustness of the welfare effects. The environments are generated by defining parameters that determine whether CASP valuations for interactions are either greater than or less than comparable valuations of subscribers, whether the BISP operates in a high cost or low cost environment, and whether linear or nonlinear pricing strategies are used on the BISP platform. Analysis demonstrates that in the majority of the examined economic environments, the BISP’s resources are more efficiently allocated when it is allowed to charge a uniform (non-discriminatory) price for priority on both the subscriber and CASP sides of the market. The efficiency gain is most pronounced when CASP valuations for interactions are high relative to subscriber valuations, when priority service is priced on an interaction basis, and when total costs are low. In a non-linear “data cap” pricing environment in which CASPs are only able to obtain priority service on an all or nothing basis for each of their subscriber interactions, priority pricing does not enhance market efficiency unless CASP values exceed subscriber values and total costs are low.

Investigation of gas purging process in pipeline by numerical method

Gas purging processes in pipeline safety maintenance were studied using the Computational Fluid Dynamics (CFD) methods. A new model (model 1) closer to actual working conditions and another two-side injection model were investigated. The simulation results showed that the relative purging efficiency of model 1 decreases compared to the ideal model (model 0), and two-sided injection model increases the efficiency relative to the single sided purging model. In addition, the models with different intake methods, outlet positions, outlet sizes and outlet pressures were simulated. If the outlet is opened after delaying some time, purging efficiency is improved. Furthermore if “relay purging” method is adopted, the efficiency is increased by 18% with two gas inlets and by 11% with a single inlet. The outlet position affects the average velocity in the last purging time. If the outlet diameter is equal or larger than that of the inlet, the purging efficiency is much higher.

Two-part tariff competition between two-sided platforms

Two-sided market models in which platforms compete in two-part tariffs, i.e., a subscription and a per-transaction fee, are often plagued by a continuum of equilibria. This paper incorporates heterogeneous trading behavior of agents into the existing framework. We show that this natural and realistic extension yields a unique equilibrium that has several reasonable properties. The equilibrium stays unique as the heterogeneity vanishes, thereby selecting a unique equilibrium from the continuum that exists under homogeneous trading behavior. We show that this equilibrium differs from equilibria obtained through other selection criteria. The analysis also provides novel empirical predictions.

Optimal Multiple Stopping with Negative Discount Rate and Random Refraction Times under Levy Models

This paper studies a class of optimal multiple stopping problems driven by Levy processes. Our model allows for a negative effective discount rate, which arises in a number of financial applications, including stock loans and real options, where the strike price can potentially grow at a higher rate than the original discount factor. Moreover, successive exercise opportunities are separated by i.i.d. random refraction times. Under a wide class of two-sided Levy models with a general random refraction time, we rigorously show that the optimal strategy to exercise successive call options is uniquely characterized by a sequence of up-crossing times. The corresponding optimal thresholds are determined explicitly in the single stopping case and recursively in the multiple stopping case.

Feedforward Active Noise Control With a New Variable Tap-Length and Step-Size Filtered-X LMS Algorithm

The fixed tap-length and step-size filtered-X least mean-square (FxLMS) algorithm is conventionally used in active noise control (ANC) systems. A tradeoff between the performance and the convergence rate is a well-known problem due to the choice of the step size. Although the variable-step-size FxLMS algorithms have been proposed for fast convergence, a long tap-length filter is frequently required in order to deal with different environments such that the convergence rate is still subject to a small step size for the long tap length. In this paper, we study a new ANC system with a variable tap-length and step-size FxLMS algorithm. Based on the assumption of an unsymmetric and two-sided exponential decay response model for the ANC control filter, the new FxLMS algorithm has the minimum mean-square deviation for the optimal filter coefficients. In the online secondary path modeling ANC system, simulation results show that the new algorithm with different kind of variable step sizes can provide significant improvements of convergence rate and noise reduction ratio, compared to the fixed-tap-length FxLMS algorithms.

Competition in Two-Sided Markets with Common Network Externalities

We study competition in two-sided markets with a common network externality rather those than with the standard inter-group effects. This type of externality occurs when both groups benefit, possibly with different intensities, from an increase in the size of one group and from a decrease in the size of the other. We explain why common externality is relevant for the health and education sectors. We focus on symmetric equilibrium and show that when the externality itself satisfies a homogeneity condition then platforms’ profits and price structures have some specific properties. Our results reveal how the rents coming from network externalities are shifted by platforms from one side to the other, according to the homogeneity degree. Prices are affected but in such a way that platforms only transfer rents from consumers to providers. In the specific but realistic case where the common network externality is homogeneous of degree zero, platforms’ profits do not depend on the intensity of the (common) network externality. This result differs from those of the two-sided models, which deal with standard positive inter-group network externality.

Net Neutrality with Competing Internet Platforms

We propose a two-sided model with two competing Internet platforms, and a continuum of Content Providers (CPs). We study the effect of a net neutrality regulation on capacity investments in the market for Internet access, and on innovation in the market for content. Under the alternative discriminatory regime, platforms charge a priority fee to those CPs which are willing to deliver their content on a fast lane. We find that under discrimination investments in broadband capacity and content innovation are both higher than under net neutrality. Total welfare increases, though the discriminatory regime is not always beneficial to the platforms as it can intensify competition for subscribers. As platforms have a unilateral incentive to switch to the discriminatory regime, a prisoner's dilemma can arise. We also consider the possibility of sabotage, and show that it can only emerge, with adverse welfare effects, under discrimination.

Innovation of New Revenue Streams in Digital Media: Journalism as Customer Relationship

Abstract Recent digital transformations of the media landscape have altered media economics. Media outlets are experiencing a decline in newspaper circulation and are struggling to develop new revenue streams within digital media. Newspaper publishers are accustomed to a two-sided revenue model geared towards readers and advertisers. In digital publishing, such two-sided revenue models must be further developed. This article describes a model in which journalistic content functions as an engine for digital traffic, and how that market position is used to promote other commercial digital services. Unlike earlier advertising models, the media company itself has become both the advertiser and the owner of the promoted services. This article’s contribution is a description of how new revenue streams are being developed around digital journalistic products. A case study of the Schibsted Media Group, including examples from the media outlets VG (Norway) and Aftonbladet (Sweden), is used here as the empirical source.

The researcher and the consultant: a dialogue on null hypothesis significance testing

Since its introduction, null hypothesis significance testing (NHST) has caused much debate. Many publications on common misunderstandings have appeared. Despite the many cautions, NHST remains one of the most prevalent, misused and abused statistical procedures in the biomedical literature. This article is directed at practicing researchers with limited statistical background who are driven by subject matter questions and have empirical data to be analyzed. We use a dialogue as in ancient Greek literature for didactic purposes. We illustrate several, though only a few, irritations that can come up when a researcher with minimal statistical background but a good sense of what she wants her study to do, and of what she wants to do with her study, asks for consultation by a statistician. We provide insights into the meaning of several concepts including null and alternative hypothesis, one- and two-sided null hypotheses, statistical models, test statistic, rejection and acceptance regions, type I and II error, p value, and the frequentist' concept of endless study repetitions.

A new fractional finite volume method for solving the fractional diffusion equation

The inherent heterogeneities of many geophysical systems often gives rise to fast and slow pathways to water and chemical movement. One approach to model solute transport through such media is by fractional diffusion equations with a space–time dependent variable coefficient. In this paper, a two-sided space fractional diffusion model with a space–time dependent variable coefficient and a nonlinear source term subject to zero Dirichlet boundary conditions is considered.Some finite volume methods to solve a fractional differential equation with a constant dispersion coefficient have been proposed. The spatial discretisation employs fractionally-shifted Grünwald formulas to discretise the Riemann–Liouville fractional derivatives at control volume faces in terms of function values at the nodes. However, these finite volume methods have not been extended to two-dimensional and three-dimensional problems in a natural manner. In this paper, a new weighted fractional finite volume method with a nonlocal operator (using nodal basis functions) for solving this two-sided space fractional diffusion equation is proposed. Some numerical results for the Crank–Nicholson fractional finite volume method are given to show the stability, consistency and convergence of our computational approach. This novel simulation technique provides excellent tools for practical problems even when a complex transition zone is involved. This technique can be extend to two-dimensional and three-dimensional problems with complex regions.

Evaporation of a thin viscous liquid film sheared by gas in a microchannel

In the present paper a 3D non-stationary two-sided mathematical model of joint motion of evaporating liquid film and cocurrent gas flow in a microchannel with local heating has been developed. This model takes into account a deformable gas–liquid interface, convective heat transfer in the liquid and the gas phases as well as temperature dependence of surface tension and liquid viscosity. Assuming the lubrication theory to be valid, the problem has been reduced to five governing equations for the film thickness, temperature fields in the gas and liquid, vapor concentration in the gas phase and gas pressure. Numerically it is shown that for films sheared by gas in microchannels vapor is transported by forced convection and diffusion, and diffusion plays the most considerable role in vapor transport at low gas velocities. Also, it is shown that concentration and thermal boundary layers are formed. The boundary layers have a specific S-shaped form. The width of the vapor track increases along the gas flow direction in front of the heater and decreasesdownstream the heater. The distance over which the width decreases is an order of magnitude higher than the heater length. This fact can be explained by the condensation of the vapor.

A Unified Distance Function Framework for Workpiece Fixturing Modeling and Analysis

Fixtures are used in almost all modern manufacturing operations. In practice, there is a wide range of specifications on the manufacturing precision and thus different requirements on workpiece locating accuracy during each production process. In view of that, this paper developed a unified signed distance function framework. Under this framework, three systems of sensitivity equations, which link the locator source errors to the resulting workpiece localization error, were derived. Accordingly, unique linear, one-sided quadratic, and two-sided quadratic models have been developed. These three models, distinguished by whether or not taking into account workpiece and/or locator curvature effects, provide a range of locating precision analysis which is illustrated and verified by several examples. The developed modeling technique can handle general fixture locating rather than being limited to certain locating schemes. The proposed models are of practical relevance and have great potential to be applied towards locating scheme evaluation, fixture design, fault diagnosis, and tolerance analysis.