Proactive Customer Service: Operational Benefits and Economic Frictions

Problem Definition: We study a service setting where the provider has information about some customers' future service needs and may initiate service for such customers proactively, if they agree to be flexible with respect to the timing of service delivery. Academic / Practical Relevance: Information about future customer service needs is becoming increasingly available through remote monitoring systems and data analytics. However, the literature has not systematically examined proactive service as a tool that can be used to better match demand to service supply when customers are strategic. Methodology: We combine i) queueing theory, and in particular a diffusion approximation developed specifically for this problem that allows us to derive analytic approximations for customer waiting times, with ii) game theory, which captures customer incentives to adopt proactive service. Results: We show that proactive service can reduce customer waiting times, even if only a relatively small proportion of customers agree to be flexible, the information lead time is limited, and the system makes occasional errors in providing proactive service - in fact we show that the system's ability to tolerate errors increases with (nominal) utilization. Nevertheless, we show that these benefits may fail to materialize in equilibrium because of economic frictions: customers will under-adopt proactive service (due to free-riding) and over-join the system (due to negative congestion-based externalities). We also show that the service provider can incentivize optimal customer behavior through appropriate pricing. Managerial Implications: Our results suggest that proactive service may offer substantial operational benefits, but caution that it may fail to fulfill its potential due to customer self-interested behavior

Can Yardstick Competition Reduce Waiting Times?

Yardstick competition is a regulatory scheme for local monopolists (e.g., hospitals), where the monopolist's reimbursement is linked to performance relative to other equivalent monopolists. This regulatory scheme is known to provide cost-reduction incentives and serves as the theoretical underpinning behind the hospital prospective reimbursement system used throughout the developed world. This paper uses a game-theoretic queueing model to investigate how yardstick competition performs in service systems (e.g., hospital emergency departments), where in addition to incentivizing cost reduction the regulator wants to incentivize waiting time reduction. We first show that the form of cost-based yardstick competition used in practice results in inefficiently long waiting times. We then demonstrate how yardstick competition can be appropriately modified to achieve the dual goal of cost and waiting-time reduction. In particular, we show that full efficiency (first-best) can be restored if the regulator makes the providers' reimbursement contingent on their service rates and is also able to charge a provider-specific "toll" to consumers. More importantly, if such a toll is not feasible, as may be the case in healthcare, we show that there exists an alternative and particularly simple yardstick-competition scheme, which depends on the average waiting time only, that can significantly improve system efficiency (second-best). This scheme is easier to implement as it does not require the regulator to have detailed knowledge of the queueing discipline. We conclude with a numerical investigation that provides insights on the practical implementation of yardstick competition for hospital Emergency Departments and also present a series of modelling extensions

Structural Evidence for Asymmetrical Nucleotide Interactions in Nitrogenase

The roles of ATP hydrolysis in electron-transfer (ET) reactions of the nitrogenase catalytic cycle remain obscure. Here, we present a new structure of a nitrogenase complex crystallized with MgADP and MgAMPPCP, an ATP analogue. In this structure the two nucleotides are bound asymmetrically by the Fe-protein subunits connected to the two different MoFe-protein subunits. This binding mode suggests that ATP hydrolysis and phosphate release may proceed by a stepwise mechanism. Through the associated Fe-protein conformational changes, a stepwise mechanism is anticipated to prolong the lifetime of the Fe-protein-MoFe-protein complex and, in turn, could orchestrate the sequence of intracomplex ET required for substrate reduction

Locating bugs without looking back

Bug localisation is a core program comprehension task in software maintenance: given the observation of a bug, e.g. via a bug report, where is it located in the source code? Information retrieval (IR) approaches see the bug report as the query, and the source code files as the documents to be retrieved, ranked by relevance. Such approaches have the advantage of not requiring expensive static or dynamic analysis of the code. However, current state-of-the-art IR approaches rely on project history, in particular previously fixed bugs or previous versions of the source code. We present a novel approach that directly scores each current file against the given report, thus not requiring past code and reports. The scoring method is based on heuristics identified through manual inspection of a small sample of bug reports. We compare our approach to eight others, using their own five metrics on their own six open source projects. Out of 30 performance indicators, we improve 27 and equal 2. Over the projects analysed, on average we find one or more affected files in the top 10 ranked files for 76% of the bug reports. These results show the applicability of our approach to software projects without history

Transit timing variation analysis of the low-mass brown dwarf KELT-1 b

We investigate whether there is a variation in the orbital period of the short-period brown dwarf-mass KELT-1 b, which is one of the best candidates to observe orbital decay. We obtain 19 high-precision transit light curves of the target using six different telescopes. We add all precise and complete transit light curves from open databases and the literature, as well as the available Transiting Exoplanet Survey Satellite (TESS) observations from sectors 17 and 57, to form a transit timing variation (TTV) diagram spanning more than 10 yr of observations. The analysis of the TTV diagram, however, is inconclusive in terms of a secular or periodic variation, hinting that the system might have synchronized. We update the transit ephemeris and determine an informative lower limit for the reduced tidal quality parameter of its host star of Q ′⋆>(8.5±3.9)×106 assuming that the stellar rotation is not yet synchronized. Using our new photometric observations, published light curves, the TESS data, archival radial velocities, and broadband magnitudes, we also update the measured parameters of the system. Our results are in good agreement with those found in previous analyses

Service Systems with Heterogeneous Customers: Investigating the Effect of Telemedicine on Chronic Care

Medical specialists treating chronic conditions typically face a heterogeneous set of patients. Such heterogeneity arises because of differences in medical conditions as well as the travel burden each patient faces to visit the clinic periodically. Given this heterogeneity, we compare the strategic behavior of revenue-maximizing and welfare-maximizing specialists and prove that the former will serve a smaller patient population, spend more time with the patients, and have shorter waiting times. We also analyze the impact of telemedicine technology on patient utility and the specialists' operating decisions. We consider both the case when specialists can freely set their own fee for service and the case when fees are set exogenously by a third-party payer. We prove that with the introduction of telemedicine the specialists become more productive and the overall social welfare increases, though some patients, unexpectedly, will be worse off. Our analytical results lead to some important policy implications for facilitating the further deployment of telemedicine in the care of chronically ill patients

Hospital Readmissions Reduction Program does not provide the right incentives: issues and remedies

The Hospital Readmissions Reduction Program (HRRP) reduces Medicare payments to hospitals with higher-than-expected readmission rates where the expected readmission rate for each hospital is determined based on the readmission levels at other hospitals. Although similar relative-performance-based schemes are shown to lead to socially optimal outcomes in other settings (e.g., cost cutting efforts), HRRP differs from these schemes in three respects: (i) deviation from the targets are adjusted using a multiplier; (ii) the total financial penalty for a hospital with higher-than-expected readmission rate is capped; and (iii) hospitals with lower-than-expected readmission rates do not receive bonus payments. We study three regulatory schemes derived from HRRP to determine the impact of each feature, and use a principal-agent model to show that: (i) HRRP over-penalizes hospitals with excess readmissions because of the multiplier and its effect can be substantial; (ii) having a penalty cap can curtail the effect of financial incentives and result in a no-equilibrium outcome when the cap is too low; and (iii) not allowing bonus payments leads to many alternative symmetric equilibria, including one where hospitals exert no effort to reduce readmissions. These results show that HRRP does not provide the right incentives for hospitals to reduce readmissions. Next we show that a bundled payment type reimbursement method, which reimburses hospitals once for each episode of care (including readmissions), leads to socially optimal cost and readmissions reduction efforts. Finally we show that, when delays to accessing care are inevitable, the reimbursement schemes need to provide additional incentives for hospitals to invest sufficiently in capacity

When to Use Provider Triage in Emergency Departments

We study triage decisions in emergency departments (EDs) and provide a general procedure for determining when to apply provider triage (PT) based on operational and financial considerations using a steady-state many-server fluid approximation. We then apply the proposed method in the setting of a teaching hospital's ED and obtain closed-form expressions for the range of arrival rates for which PT outperforms the traditional nurse triage economically. We show that the proposed solution methodology based on this approximation procedure is asymptotically optimal under a many-server asymptotic regime. We also demonstrate via simulation experiments that the proposed policy performs within 0.82% of the best solution obtained via a computationally intensive total enumeration method

Effective Mass Dirac-Morse Problem with any kappa-value

The Dirac-Morse problem are investigated within the framework of an approximation to the term proportional to $1/r^2$ in the view of the position-dependent mass formalism. The energy eigenvalues and corresponding wave functions are obtained by using the parametric generalization of the Nikiforov-Uvarov method for any $\kappa$-value. It is also studied the approximate energy eigenvalues, and corresponding wave functions in the case of the constant-mass for pseudospin, and spin cases, respectively.Comment: 12 page

Nitrogenase Complexes: Multiple Docking Sites for a Nucleotide Switch Protein

Adenosine triphosphate (ATP) hydrolysis in the nitrogenase complex controls the cycle of association and dissociation between the electron donor adenosine triphosphatase (ATPase) (Fe-protein) and its target catalytic protein (MoFe-protein), driving the reduction of dinitrogen into ammonia. Crystal structures in different nucleotide states have been determined that identify conformational changes in the nitrogenase complex during ATP turnover. These structures reveal distinct and mutually exclusive interaction sites on the MoFe-protein surface that are selectively populated, depending on the Fe-protein nucleotide state. A consequence of these different docking geometries is that the distance between redox cofactors, a critical determinant of the intermolecular electron transfer rate, is coupled to the nucleotide state. More generally, stabilization of distinct docking geometries by different nucleotide states, as seen for nitrogenase, could enable nucleotide hydrolysis to drive the relative motion of protein partners in molecular motors and other systems