Hamiltonian model of heat conductivity and Fourier law

We investigate the stationary nonequilibrium states of a quasi one-dimensional system of heavy particles whose interaction is mediated by purely elastic collisions with light particles, in contact at the boundary with two heat baths with fixed temperatures $T^+$ and $T^-$. It is shown that Fourier law is satisfied with a thermal conductivity proportional to $\sqrt{T(x)}$ where $T(x)$ is the local temperature. Entropy flux and entropy production are also investigated.Comment: 12 pages, 4 figure

Measuring Imputed Cost in the Semiconductor Equipment Supply Chain

We consider the order-fulfillment process of a supplier producing a customized capital good, such as production equipment, commercial aircraft, medical devices, or defense systems. As is common in these industries, prior to receiving a firm purchase order from the customer, the supplier receives a series of shared forecasts, which are called “soft orders.” Facing a stochastic internal manufacturing lead time, the supplier must decide at what time to begin the fulfillment of the order. This decision requires a trade-off between starting too early, leading to potential holding or cancellation costs, and starting too late, leading to potential delay costs. We collect detailed data of shared forecasts, actual purchase orders, production lead times, and delivery dates for a supplier-buyer dyad in the semiconductor equipment supply chain. Under the assumption that the supplier acts rationally, optimally balancing the cancellation, holding, and delay costs, we are able to estimate the corresponding imputed cost parameters based on the observed data. Our estimation results reveal that the supplier perceives the cost of cancellation to be about two times higher and the holding costs to be about three times higher than the delay cost. In other words, the supplier is very conservative when commencing the order fulfillment, which undermines the effectiveness of the overall forecast-sharing mechanism

Information Sharing in a Long-Term Supply Chain Relationship: The Role of Customer Review Strategy

In this paper, we study the practice of forecast sharing and supply chain coordination with a game-theoretical model. We find that in a one-shot version of the game, forecasts are not shared truthfully by the customer. The supplier will rationally discount the forecast information in her capacity allocation. This results in Pareto suboptimality for both supply chain parties. However, we show that a more efficient, truth-sharing outcome can emerge as an equilibrium from a long-term relationship. In this equilibrium, forecast information is transmitted truthfully and trusted by the supplier, who in turn allocates the system-optimal capacity. This leaves both the customer and the supplier better-off, compared to the nontruthful-sharing equilibrium. We identify a multiperiod review strategy profile that supports the truthful-sharing equilibrium. The key element of this strategy is that the supplier computes a scoring index of the customer\u27s behavior that is updated over time and used to evaluate if the customer has sufficient incentive to share his private information truthfully in each transaction of the repeated game. Compared to trigger strategies, review strategies are more tolerant but require diligence and more monitoring effort

An Empirical Analysis of Forecast Sharing in the Semiconductor Equipment Supply Chain

We study the demand forecast-sharing process between a buyer of customized production equipment and a set of equipment suppliers. Based on a large data collection we undertook in the semiconductor equipment supply chain, we empirically investigate the relationship between the buyer\u27s forecasting behavior and the supplier\u27s delivery performance. The buyer\u27s forecasting behavior is characterized by the frequency and magnitude of forecast revisions it requests (forecast volatility) as well as by the fraction of orders that were forecasted but never actually purchased (forecast inflation). The supplier\u27s delivery performance is measured by its ability to meet delivery dates requested by the customers. Based on a duration analysis, we are able to show that suppliers penalize buyers for unreliable forecasts by providing lower service levels. Vice versa, we also show that buyers penalize suppliers that have a history of poor service by providing them with overly inflated forecasts

Introducing IR to Medical Students Interested in Primary Care Specialties

Introduction: Over the last several years, interventional radiologists have become increasingly recognized as part of a collaborative healthcare team. At the same time, interventional radiology (IR) is a field poorly represented in many medical school curricula. As IR management options are increasingly incorporated into the clinician’s arsenal, representation during medical education is critical. Several studies have demonstrated that interventional radiology interest group (IRIG) presentations and demonstrations increase knowledge and excitement about the specialty amongst medical students. However, current literature investigating the effect of these presentations on students interested in primary care specialties is lacking. Our study demonstrates that presenting cases specifically targeted toward students interested in primary care specialties increases their knowledge about the role of IR in their future practice.Methods: Case presentations were given to students who attended interest group meetings in family medicine, emergency medicine, pediatrics, and internal medicine. Presentations were developed specifically to consist of cases that are relevant to each interest group’s respective field. The majority of students were in their preclinical years and interested in a variety of non-radiology specialties. Surveys were administered prior to the presentation and following the presentation (7 questions each). All questions were answered on a Likert scale of 1-5 (1—disagree and 5—agree). Questions were centered around general knowledge of IR, the role of IR within their field, and the benefits of IR to their future practice. Descriptive statistics were calculated based on these results.Results: Responses from 81 participants to every question suggested an overall increase in the knowledge of the field of IR following the case presentation. The mean value to the question “I understand the role of IR in my specialty of interest” increased from 2.7 to 3.6 after the presentation. Students’ average response to the question, “I understand some IR procedures” increased 1.3 points on the scale.Conclusions: Medical students are generally not exposed to IR as a specialty despite its expanding role in clinical practice. Increasing medical student familiarity with IR is essential to producing physicians with a broad understanding of the management options at their disposal. Targeted case presentations given to pre-clinical and clerkship-level medical students interested in primary care specialties were effective in increasing understanding of the role of IR in their specialty of interest. Student-led presentations using interest groups as a networking platform are an effective method for forming first impressions and exposing future doctors to the applications of interventional radiology in their practice.https://scholarlycommons.henryford.com/merf2019edu/1001/thumbnail.jp

The contribution of feminist biblical hermeneutics to a theology of ministries

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

Optimizing astrophotonic spatial reformatters using simulated on-sky performance

One of the most useful techniques in astronomical instrumentation is image slicing. It enables a spectrograph to have a more compact angular slit, whilst retaining throughput and increasing resolving power. Astrophotonic components like the photonic lanterns and photonic reformatters can be used to replace bulk optics used so far. This study investigates the performance of such devices using end-to-end simulations to approximate realistic on-sky conditions. It investigates existing components, tries to optimize their performance and aims to understand better how best to design instruments to maximize their performance. This work complements the recent work in the field and provides an estimation for the performance of the new components.Comment: Conference proceedings in SPIE 2018 Austin Texa

Non-contrast renal magnetic resonance imaging to assess perfusion and corticomedullary differentiation in health and chronic kidney disease

AIMS Arterial spin labelling (ASL) MRI measures perfusion without administration of contrast agent. While ASL has been validated in animals and healthy volunteers (HVs), application to chronic kidney disease (CKD) has been limited. We investigated the utility of ASL MRI in patients with CKD. METHODS We studied renal perfusion in 24 HVs and 17 patients with CKD (age 22-77 years, 40% male) using ASL MRI at 3.0T. Kidney function was determined using estimated glomerular filtration rate (eGFR). T1 relaxation time was measured using modified look-locker inversion and xFB02;ow-sensitive alternating inversion recovery true-fast imaging and steady precession was performed to measure cortical and whole kidney perfusion. RESULTS T1 was higher in CKD within cortex and whole kidney, and there was association between T1 time and eGFR. No association was seen between kidney size and volume and either T1, or ASL perfusion. Perfusion was lower in CKD in cortex (136 ± 37 vs. 279 ± 69 ml/min/100 g; p < 0.001) and whole kidney (146 ± 24 vs. 221 ± 38 ml/min/100 g; p < 0.001). There was significant, negative, association between T1 longitudinal relaxation time and ASL perfusion in both the cortex (r = -0.75, p < 0.001) and whole kidney (r = -0.50, p < 0.001). There was correlation between eGFR and both cortical (r = 0.73, p < 0.01) and whole kidney (r = 0.69, p < 0.01) perfusion. CONCLUSIONS Significant differences in renal structure and function were demonstrated using ASL MRI. T1 may be representative of structural changes associated with CKD; however, further investigation is required into the pathological correlates of reduced ASL perfusion and increased T1 time in CKD

Extraterrestrial Moessbauer Spectroscopy: More than Three Years of Mars Exploration and Developments for Future Missions

The NASA Mars Exploration Rovers (MER), Spirit and Opportunity, landed on the Red Planet in January 2004. Both rovers are equipped with a miniaturized Moessbauer spectrometer MIMOS II. Designed for a three months mission, both rovers and both Moessbauer instruments are still working after more than three years of exploring the Martian surface. At the beginning of the mission, with a landed intensity of the Moessbauer source of 150 mCi, a 30 minute touch and go measurement produced scientifically valuable data while a good quality Moessbauer spectrum was obtained after approximately eight hours. Now, after about five halflives of the sources have passed, Moessbauer integrations are routinely planned to last approx.48 hours. Because of this and other age-related hardware degradations of the two rover systems, measurements now occur less frequently, but are still of outstanding quality and scientific importance. Summarizing important Moessbauer results, Spirit has traversed the plains from her landing site in Gusev crater and is now, for the greater part of the mission, investigating the stratigraphically older Columbia Hills. Olivine in rocks and soils in the plains suggests that physical rather than chemical processes are currently active