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The multi-commodity network flow problem (MCNF) consists in routing a set of commodities through a capacitated network at minimum cost and is relevant for routing containers in liner shipping networks. As commodity transit times are often a critical factor, the literature has introduced hard limits on commodity transit times. In practical contexts, however, these hard limits may fail to provide sufficient flexibility since routes with even tiny delays would be discarded. Motivated by a major liner shipping operator, we study an MCNF generalization where transit time restrictions are modeled as soft constraints, in which delays are discouraged using penalty functions of transit time. Similarly, early commodity arrivals can receive a discount in cost. We derive properties that distinguish this model from other MCNF variants and adapt a column generation procedure to efficiently solve it. Extensive numerical experiments conducted on realistic liner shipping instances reveal that the explicit consideration of penalty functions can lead to significant cost reductions compared to hard transit time deadlines. Moreover, the penalties can be used to steer the flow towards slower or faster configurations, resulting in a potential increase in operational costs, which generates a trade-off that we quantify under varying penalty functions.

This paper introduces the transit time constrained fixed charge multi-commodity network design problem. Transit times are origin-to-destination time limits for the commodities, which appear for example in transport systems with perishable goods. We discuss how to model the problem and present three different formulations of it. The first formulation is an exponential size path formulation, which we solve with a branch-and-price algorithm. Several speed up techniques from the literature on fixed charge multi-commodity network design problems are implemented, such as lifted cover inequalities and the recently proposed deep dual-optimal inequalities. In an extensive set of computational experiments, we show that these inequalities significantly improve the performance of the algorithm. The other two formulations are of polynomial size: one uses path indices and the other uses time indices. While the branch-and-price algorithm outperforms solving the compact formulations with a general-purpose mixed-integer programming solver, the study of compact models helps better understand the problem, and we can use them as benchmarks. A detailed sensitivity analysis of the branch-and-price algorithm shows that longer transit times and an increased ratio of fixed charge to flow cost increase the difficulty of solving the problem whereas the arc capacity has less impact. We further discuss in-depth implementational details.

We consider a strategic infrastructure and tanker fleet sizing problem in the liquefied natural gas business. The goal is to minimize long-term on-shore infrastructure and tanker investment cost combined with interrelated expected cost for operating the tanker fleet. A non-linear arc-based model and an exact solution method based on a set-partitioning formulation are developed. The latter approach allows very fast solution times. Computational results for a case study with a liner shipping company are presented, including an extensive sensitivity analysis to account for limited predictability of key parameter values, to analyze the solutions’ robustness and to derive basic decision rules.

Pediatric formulation development requires an understanding of the physico-chemical stability and the taste of the pharmaceutical drug product. Two model active pharmaceutical ingredients (compound X and compound Y) were used to develop a powder for reconstitution to a suspension and a solution dosage form after dilution with purified water. X-ray powder diffraction was used to monitor the physical stability of compound X in the suspension and high pressure liquid chromatography was used to monitor the chemical stability of compound Y in the solution. The most stable suspension (formulation T) and solution (formulation Z) were used to assess the change in taste-perception by different flavors using the Astree™ electronic tongue. The suspension was determined to be stable for 43 days and 21 days respectively at 5 °C and 25 °C/60% RH. Compound Y solution was chemically stable for up to 30 days at 25 °C/60% RH. The taste of the suspension was improved by Lemon and Cherry flavors. The taste of the solution was made better by Vanilla, Cherry, and Strawberry flavors. The significance of these results is that the e-Tongue can be used in the early stages of formulation development to eliminate flavors that do little to improve the palatability of a formulation.

Introduction This article describes an observational study of caring behaviors in the emergency departments of 4 Ascension Health hospitals and the impact of these behaviors on patient loyalty to the associated hospital. These hospitals were diverse in size and geography, representing 3 large urban community hospitals in metropolitan areas and 1 in a midsized city. Methods Research assistants from Purdue University (West Lafayette, IN) conducted observations at the first study site and validated survey instruments. The Purdue research assistants trained contracted observers at the subsequent study sites. The research assistants conducted observational studies of caregivers in the emergency departments at 4 study sites using convenience sampling of patients. Caring behaviors were rated from 0 (did not occur) to 5 (high intensity). The observation included additional information, for example, caregiver roles, timing, and type of visit. Observed and unobserved patients completed exit surveys that recorded patient responses to the likelihood-to-recommend (loyalty) questions, patient perceptions of care, and demographic information. Results Common themes across all study sites emerged, including (1) the area that patients considered most important to an ED experience (prompt attention to their needs upon arrival to the emergency department); (2) the area that patients rated as least positive in their actual ED experience (prompt attention to their needs upon arrival to the emergency department); (3) caring behaviors that significantly affected patient loyalty (eg, making sure that the patient is aware of care-related details, working with a caring touch, and making the treatment procedure clearly understood by the patient); and (4) the impact of wait time to see a caregiver on patient loyalty. A number of correlations between caring behaviors and patient loyalty were statistically significant (P Discussion The study results raised considerations for ED caregivers, particularly with regard to those caring behaviors that are most closely linked to patient loyalty but that occurred least frequently. The study showed through factor analysis that some caring behaviors tended to occur together, suggesting an underlying, unifying dimension to that factor.

A thin film of MgB 2 , grown on a SiN–Si substrate, with a superconducting transition temperature, T c , near 39 K has been irradiated with γ-rays from a 60 Co source. The total dose was 100 Krads (Si). Its pre- and post-irradiation noise has been measured and noise spectral density plots made. No change in d R /d T , pre- and post-irradiation was measured. At the mid-point of the transition, T = 38.24 K, a noise spectral density S V = 0.34 nV Hz −1/2 was measured at 10 Hz. The temperature noise, K n , of the MgB 2 film at different frequencies is compared to that of high temperature superconducting (HTS) thin films (YBaCuO and GdBaCuO with T c ∼ 90 K) used currently in HTS transition-edge bolometers. Even with the observed post-irradiation small increase in noise, its lower T c and K n values predict that high performance far IR bolometers can be developed using MgB 2 as a thermistor.

The external quantum efficiency in the spectral wavelength range 5–500 nm of a large active area Pt/n-type GaN Schottky photodiode that exhibits low reverse bias leakage current, is reported. The Schottky photodiodes were fabricated from n−/n+ epitaxial layers grown by low pressure metalorganic vapour phase epitaxy on single crystal c-plane sapphire. The current–voltage ( I – V ) characteristics of several 0.25 cm2 devices are presented together with the capacitance–voltage ( C – V ) characteristics of one of these devices. A leakage current as low as 14 pA at 0.5 V reverse bias is reported, for a 0.25 cm2 diode. The ultraviolet quantum efficiency measurements show that the diodes can be used as radiation hard detectors for the 5–365 nm spectral range without the use of visible blocking filters. A peak responsivity of 77.5 mA/W at 320 nm is reported for one of the fabricated devices, corresponding to a spectral detectivity, D * = 1.5 × 1 0 14 cm Hz 1 / 2 W - 1 . The average detectivity between 250 and 350 nm, for the same device, is reported to be D ¯ * = 1.3 × 1 0 14 cm Hz 1 / 2 W - 1 . The spatial responsivity uniformity variation was established, using H2 Lyman-α radiation, to be ±3% across the surface of a typical 0.25 cm2 diode.