Project design with limited commitment and teams

We study the interaction between a group of agents who exert effort to complete a project and a manager who chooses its objectives. The manager has limited commitment power so that she can commit to the objectives only when the project is sufficiently close to completion. We show that the manager has incentives to extend the project as it progresses. This result has two implications. First, the manager will choose a larger project if she has less commitment power. Second, the manager should delegate the decision rights over the project size to the agents unless she has sufficient commitment power

Wind-US Code Physical Modeling Improvements to Complement Hypersonic Testing and Evaluation

This report gives an overview of physical modeling enhancements to the Wind-US flow solver which were made to improve the capabilities for simulation of hypersonic flows and the reliability of computations to complement hypersonic testing. The improvements include advanced turbulence models, a bypass transition model, a conjugate (or closely coupled to vehicle structure) conduction-convection heat transfer capability, and an upgraded high-speed combustion solver. A Mach 5 shock-wave boundary layer interaction problem is used to investigate the benefits of k- s and k-w based explicit algebraic stress turbulence models relative to linear two-equation models. The bypass transition model is validated using data from experiments for incompressible boundary layers and a Mach 7.9 cone flow. The conjugate heat transfer method is validated for a test case involving reacting H2-O2 rocket exhaust over cooled calorimeter panels. A dual-mode scramjet configuration is investigated using both a simplified 1-step kinetics mechanism and an 8-step mechanism. Additionally, variations in the turbulent Prandtl and Schmidt numbers are considered for this scramjet configuration

AFM imaging and nanoindentation of polymer of intrinsic microporosity PIM-1

Polymers of intrinsic microporosity (PIMs) have promising gas adsorption properties for potential applications such as incorporation into high-pressure hydrogen storage tanks in an effort to increase the storage capacity or decrease the operating pressure. Such applications require detailed mechanical characterisation and determination of the structure-properties relationships to enable optimisation of the interface between the polymer and the tank. In this study, we show that Atomic Force Microscopy (AFM) nanoindentation can be used to determine the elastic modulus of cast PIM-1 films and that this property is depth-dependent. Average values of elastic modulus obtained experimentally were 1.87 GPa and are compared with elastic tensile modulus and storage tensile modulus obtained in previous studies. In addition, Scanning Electron Microscopy (SEM) and AFM imaging was performed to investigate the surface structure of the cast PIM-1 film, which has been shown to be highly granular

Potentiation of Carboplatin-Mediated DNA Damage by the Mdm2 Modulator Nutlin-3a in a Humanized Orthotopic Breast-to-Lung Metastatic Model

Triple-negative breast cancers (TNBC) are typically resistant to treatment, and strategies that build upon frontline therapy are needed. Targeting the murine double minute 2 (Mdm2) protein is an attractive approach, as Mdm2 levels are elevated in many therapy-refractive breast cancers. The Mdm2 protein-protein interaction inhibitor Nutlin-3a blocks the binding of Mdm2 to key signaling molecules such as p53 and p73α and can result in activation of cell death signaling pathways. In the present study, the therapeutic potential of carboplatin and Nutlin-3a to treat TNBC was investigated, as carboplatin is under evaluation in clinical trials for TNBC. In mutant p53 TMD231 TNBC cells, carboplatin and Nutlin-3a led to increased Mdm2 and was strongly synergistic in promoting cell death in vitro. Furthermore, sensitivity of TNBC cells to combination treatment was dependent on p73α. Following combination treatment, γH2AX increased and Mdm2 localized to a larger degree to chromatin compared with single-agent treatment, consistent with previous observations that Mdm2 binds to the Mre11/Rad50/Nbs1 complex associated with DNA and inhibits the DNA damage response. In vivo efficacy studies were conducted in the TMD231 orthotopic mammary fat pad model in NOD.Cg-Prkdc(scid)Il2rg(tm1Wjl)/SzJ (NSG) mice. Using an intermittent dosing schedule of combined carboplatin and Nutlin-3a, there was a significant reduction in primary tumor growth and lung metastases compared with vehicle and single-agent treatments. In addition, there was minimal toxicity to the bone marrow and normal tissues. These studies demonstrate that Mdm2 holds promise as a therapeutic target in combination with conventional therapy and may lead to new clinical therapies for TNBC

Diagenesis of archaeological bone and tooth

An understanding of the structural complexity of mineralised tissues is fundamental for exploration into the field of diagenesis. Here we review aspects of current and past research on bone and tooth diagenesis using the most comprehensive collection of literature on diagenesis to date. Environmental factors such as soil pH, soil hydrology and ambient temperature, which influence the preservation of skeletal tissues are assessed, while the different diagenetic pathways such as microbial degradation, loss of organics, mineral changes, and DNA degradation are surveyed. Fluctuating water levels in and around the bone is the most harmful for preservation and lead to rapid skeletal destruction. Diagenetic mechanisms are found to work in conjunction with each other, altering the biogenic composition of skeletal material. This illustrates that researchers must examine multiple diagenetic pathways to fully understand the post-mortem interactions of archaeological skeletal material and the burial environment

Optimal reservation policies and market segmentation

When operating in a market with heterogeneous customers, a service firm (e.g., a car rental company or a hotel) needs to manage its capacity so as to maximize its revenue. To gauge the potential demand, a service firm often allows each customer to reserve a unit of service in advance. However, to avoid the loss associated with “no-shows”, service firms may require a non-refundable deposit. To determine an optimal reservation policy with a non-refundable deposit, we consider the case in which the market is divided into four segments (high vs. low valuation and high vs. low show-up probability). When customer demand and the firm׳s capacity are large so that they can be approximated by continuous values, we determine the optimal reservation policy analytically, and we establish analytical conditions under which the firm should discriminate against (i.e., price out) certain customer segments. For the case when customer demand and the firm׳s capacity are finite so that they take on discrete values, we find that some of the insights obtained from the “continuous” case continue to hold especially when the firm׳s capacity is large. However, the key difference is that in the former case, the firm discriminates mostly based on customers׳ valuation, whereas in the latter case it discriminates mostly based on customers׳ show-up probability

Multi-agent distributed method for dynamic power system rebalancing

Global efforts aim at utilizing the available information technology in order to enhance the power grid with resilience properties, precise accounting and new services. Towards this end, we provide methods to support an adaptive power grid and study the relative changes in supply and/or demand while in a quasi-steady state. Acknowledging that the absolute amount of the power demand/supply is not always the limiting factor, the proposed algorithm focuses on the deviations in the generated and/or demanded resources, as well as the location of these changes in the grid. Through our experimental evaluation study we show that the algorithm leads to a faster reconvergence to a new steady state operating point when compared to convergence from initial conditions after changes complete. We also show that changes can be resolved in a distributed and local manner, needing only limited and fast communication with nodes that are far from the locus of change

Distributed Optimization-Based Control of Electrical Distribution Systems with Active Distributed Resources

This paper describes a framework to support the electricity distribution system operator (DSO) in identifying the appropriate control strategy in a system due to the stochastic nature of the integrated intermittent distributed generation. A distributed optimization and control algorithm is applied in order to determine the look-ahead allocation of distributed resources for risk mitigation, as well as real-time controls to attempt to ensure that the electrical distribution system (DS) is managed in a reliable and cost-effective manner. The management of these active resources will thus ensure that the DS can be optimized to operate in an efficient manner while providing adequate security

Revisiting Turbulence Model Validation for High-Mach Number Axisymmetric Compression Corner Flows

Two axisymmetric shock-wave/boundary-layer interaction (SWBLI) cases are used to benchmark one- and two-equation Reynolds-averaged Navier-Stokes (RANS) turbulence models. This validation exercise was executed in the philosophy of the NASA Turbulence Modeling Resource and the AIAA Turbulence Model Benchmarking Working Group. Both SWBLI cases are from the experiments of Kussoy and Horstman for axisymmetric compression corner geometries with SWBLI inducing flares of 20 and 30 degrees, respectively. The freestream Mach number was approximately 7. The RANS closures examined are the Spalart-Allmaras one-equation model and the Menter family of kappa omega two equation models including the Baseline and Shear Stress Transport formulations. The Wind-US and CFL3D RANS solvers are employed to simulate the SWBLI cases. Comparisons of RANS solutions to experimental data are made for a boundary layer survey plane just upstream of the SWBLI region. In the SWBLI region, comparisons of surface pressure and heat transfer are made. The effects of inflow modeling strategy, grid resolution, grid orthogonality, turbulent Prandtl number, and code-to-code variations are also addressed

WaSH-UP Sustainable Livelihoods and Business Operations

The Water, Sanitation and Hygiene Upgrading Programme (WaSH- - UP) aims to alleviate South Africa’s water and sanitation crisis by collaborating with community members to develop a sustainable maintenance plan for public sanitation facilities. The goal of this project was to create a model to fund the Langrug facility by teaming up with co-researchers to implement a kiosk for selling health products. The project yielded a unique management plan, guidelines for savings group organization, and insight into informal settlement social complexities