A5002910777- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Advanced Queuing Theory Analysis
- Supply Chain and Inventory Management
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Organ Transplantation Techniques and Outcomes
- Economic theories and models
- Banking stability, regulation, efficiency
- Liver Disease and Transplantation
- Sustainable Supply Chain Management
- Healthcare Operations and Scheduling Optimization
- Healthcare Policy and Management
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- State Capitalism and Financial Governance
- Consumer Market Behavior and Pricing
- History and Developments in Astronomy
- Liver Disease Diagnosis and Treatment
- Global Financial Regulation and Crises
- Superconducting Materials and Applications
- Transportation Planning and Optimization
- Recycling and Waste Management Techniques
Carnegie Mellon University
2010-2024
Turgut Özal University
2024
Sivas State Hospital
2024
Haliç University
2020-2023
Malatya Devlet Hastanesi
2021
Inonu University
2017
Doğuş University
2017
Ege University
1989-2016
We consider the problem of designing an efficient system for allocating donated livers to patients waiting transplantation. The trade-off between medical urgency and efficiency is at heart liver allocation problem. model transplant list as a multiclass fluid overloaded queues, which captures disease evolution by allowing switch classes, i.e., health levels. bicriteria objective minimizing total number patient deaths while transplantation (NPDWT) maximizing quality-adjusted life years (QALYs)...
Motivated by a collaborative study with one of the most comprehensive ocular imaging programs in United States, we investigate underlying three-way trade-off among operational, clinical, and financial considerations physicians’ decisions about ordering tests. Laboratory tests may be processed parallel thus have limited effect on patients’ waiting times; tests, contrast, require patient presence directly influence times. We use strategic queueing framework to model physician’s decision show...
Organ transplantation has been proven to be an effective treatment for end-stage kidney, heart, liver and lung diseases. Recognizing the effects of health inequalities related is important underserved populations. This scoping review aims map scope operational management literature on corresponding deceased donor organ highlight knowledge gaps direct future research. The document also describes some open questions that we hope will continue attract attention researchers interested in aspects...
We consider outsourcing in two important service settings: call center and order fulfillment operations. An factor both is the inherent economies of scale. Therefore, we advance a unifying model covering applications study associated contracting problem under information asymmetry. At time contracting, firm, “the originator,” faces uncertainty regarding demand volume but has private about its probability distribution. The true quickly observed once commences. provider invests capacity before...
We consider an assemble-to-order generalized M-system with multiple components and products, batch ordering of components, random lead times, lost sales. model the system as infinite-horizon Markov decision process seek optimal policy that specifies when a should be produced (i.e., inventory replenishment) whether arriving demand for each product satisfied allocation). characterize replenishment allocation policies under mild condition on component sizes via new type policy:...
Since the introduction of MELD-based allocation system, women are now 30% less likely than men to undergo liver transplant (LT) and have 20% higher waitlist mortality. These disparities in large part due height differences though no national policies been implemented reduce sex disparities. Patients were identified using Scientific Registry Transplant Recipients (SRTR) from 2014 2019. categorized into five groups by first dividing thirds then shortest third three capture more granular most...
In this paper, we present the results of a multisite photometric campaign devoted to γ Doradus type variable HR 8799. From Johnson and Strömgren data, were able identify three independent frequencies (f1 = 1.9791 cycle d−1, f2 1.7268 d−1 f3 1.6498 d−1) as well another signal, which are coupling term between two (f4 f1 − 0.2479 d−1). These four account for all observed variations down 1σ significance level. We discuss possible interpretation these using model quasi-stochastic amplitude...
Considering a sample of 20 eclipsing binary systems with δ Scuti type primaries, we discovered that there is possible relation among the pulsation periods primaries and orbital systems. According to this empirical relation, longer period binary, its pulsating primary. Among sample, masses secondaries separations between components are known for eight which log Ppuls versus F (the gravitational pull exerted per gram matter on surface by secondaries) diagram also verifies such an interrelation...
We consider a congestible system serving multiple classes of customers who differ in their delay sensitivity and valuation service (or product). Customers are endowed with convex-concave cost functions. A manager offers menu lead times corresponding prices to arriving customers, then choose the lead-time–price pair that maximizes net utility (value minus disutility price). investigate how such menus should be chosen dynamically (depending on backlog) maximize welfare. formulate novel fluid...
PG 1159-035, a pre-white dwarf with T_eff=140,000 K, is the prototype of both two classes: PG1159 spectroscopic class and DOV pulsating class. Previous studies 1159-035 photometric data obtained Whole Earth Telescope (WET) showed rich frequency spectrum allowing identification 122 pulsation modes. In this work, we used all available WET from 1983, 1985, 1989, 1993 2002 to identify periods identified 76 additional modes, increasing 198 number known modes in largest detected any star besides...
There are disparities in access to livers based on transplant patients’ height, which disproportionately affects Hispanics, Asians, and women (across all ethnicities), because short patients can receive transplants from a smaller pool of available deceased donors for medical reasons. Reduced likelihood transplantation leads higher mortality rates longer waiting times. We analyze fairness within the current U.S. liver allocation system where priority dynamically, their model end-stage disease...
We consider a continuous-time, rate-based model of network revenue management. Under mild assumptions, we construct simple ε-optimal bid-price control, which can be viewed as perturbation control in the classical sense [Williamson, E. L. 1992. Airline seat control. Ph.D. thesis, MIT, Cambridge, MA]. show that associated process forms martingale and corresponding booking controls converge an appropriate to optimal ε tends 0. Moreover, there exists generalized where is used conjunction with...
The Pennsylvania Adoption Exchange (PAE) helps caseworkers who represent children in Pennsylvania’s child welfare system by recommending prospective families for adoption. We describe PAE’s operational challenges using caseworker surveys, and analyze outcomes through a regression analysis of data collected over multiple years. A match recommendation spreadsheet tool implemented PAE incorporates insights from this allows managers to better utilize available information. Using discrete-event...
Within service systems, tasks can encompass diverse functionalities. In a two-phase queuing model featuring two customer priority classes, our study discerns distinct task functionalities executed by the first-phase server (referred to as auxiliary server). These aim facilitate priority-based second-phase expert). Load-balancing alleviate expert's workload, while differentiation enhance accurate prioritization in second phase reducing misclassification. With customers for both and expert...
The Importance of Considering System Congestion When Acquiring Used Items for Remanufacturing condition used items obtained by remanufacturers often varies widely and may only be truly known after an inspection. In “Technical Note–Optimal Procurement in Systems with Uncertain Used-Item Condition,” Nadar, Akan, Debo, Scheller-Wolf study the procurement problem taking into account this pre-inspection uncertainty as well quantities available different quality levels. authors provide a novel...
We consider an assemble‐to‐order (ATO) system with multiple products, components which may be demanded in different quantities by possible batch ordering of components, random lead times, and lost sales. model the as infinite‐horizon Markov decision process under average cost criterion. A control policy specifies when a should produced, whether arriving demand for each product satisfied. Previous work has shown that lattice‐dependent base‐stock rationing (LBLR) is optimal stationary special...
We provide a new method for solving very general model of an assemble-to-order system: multiple products, components that may be demanded in different quantities by batch production, random lead times, and lost sales, modeled as Markov decision process under the discounted cost criterion. A control policy specifies when should produced whether arriving demand each product satisfied. As optimal solutions our are computationally intractable even moderately sized systems, we approximate...
We discuss new photometric data collected on the γ Dor variables HD 224945 and 224638. Multiperiodicity was detected in both stars, thanks to clear spectral window of a multisite campaign that involved five observatories. shows shortest period among i.e., 0.3330 d. The pulsation behaviour is very different: displays set frequencies spread over an interval much larger than clearly found evidence for amplitude variations excited modes by comparing from different years. 224638 are best examples...
New photometric observations of the Algol-type binary system AB Cassiopeiae were obtained in B and V filters during 2001–2002 observing season at Ege University Observatory. As expected, new light curves system, which analyzed using Wilson-Devinney code, exhibit short-period oscillations due to pulsation primary component. A q-value search was performed, mass ratio found be 0.19. The residuals from observed-minus-computed reveal From clear cycles pulsations curves, we determined 21 times...