One-dimensional cutting stock problems and solution procedures

This paper provides an introduction to one-dimensional cutting stock problems and solution procedures. The first problem considered requires that both trim loss and pattern changes be controlled. Both linear programming and sequential heuristic procedures are discussed along with the ways they can be used jointly to generate the best possible solutions to this type of problem. Two other important classes of one-dimensional problems are discussed along with ways in which they can be solved.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30249/1/0000644.pd

Solving the two-stage cutting stock problem

This paper describes an important class of cutting stock problems not previously discussed in the literature. The problem is one of determining the patterns to be used in a two-stage cutting process with restrictions imposed on the locations of cuts in the first stage. A particularly difficult version of this problem from the plastic film industry is presented and solved.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23683/1/0000652.pd

Cutting stock problems and solution procedures

This paper discusses some of the basic formulation issues and solution procedures for solving one- and two- dimensional cutting stock problems. Linear programming, sequential heuristic and hybrid solution procedures are described. For two-dimensional cutting stock problems with rectangular shapes, we also propose an approach for solving large problems with limits on the number of times an ordered size may appear in a pattern.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29128/1/0000167.pd

Load planning for shipments of low density products

This paper presents a complex computer-based heuristic procedure for sizing customer orders and developing three dimensional load diagrams for rail and truck shipment of low density products. This heuristic procedure was developed for, and is in various phases of implementation at, a large multinational U.S.-based consumer products company. Products are shipped daily in high volume from inventory in corrugated containers of various sizes depending on the product package sizes and customer requirements. Vehicles used include railcars, truck trailers and tandem truck trailers, which also vary in size depending upon need and availability. In most cases, product volume or material handling considerations limit the amount of product loaded into vehicles before weight restrictions are met. Hence, the emphasis here is on low density products. The procedure developed has been demonstrated to significantly increase vehicle utilization, and improve customer service. It is fast and accurate enough to be used in real time during the order entry process. It has also been used successfully in a vehicle feasibility study of single versus tandem trailers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28752/1/0000582.pd

One-dimensional cutting stock decisions for rolls with multiple quality grades

This paper presents a procedure for solving one-dimensional cutting stock problems when both the master rolls and customer orders have multiple quality gradations.The procedure described here is a two-stage sequential heuristic. An innovative shadow price-based procedure is first used to select slitting patterns for master rolls with variable quality characteristics. Then a residual problem for the available first-quality (`perfect') master rolls is solved with a linear programming model.An important characteristic of this approach is its robustness. The procedure can deal effectively with problems of varying size and complexity and can also easily be adapted to changing circumstances with respect to production quality and demand.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28751/1/0000581.pd

Optimisation of Quantum Trajectories Driven by Strong-field Waveforms

Quasi-free field-driven electron trajectories are a key element of strong-field dynamics. Upon recollision with the parent ion, the energy transferred from the field to the electron may be released as attosecond duration XUV emission in the process of high harmonic generation (HHG). The conventional sinusoidal driver fields set limitations on the maximum value of this energy transfer, and it has been predicted that this limit can be significantly exceeded by an appropriately ramped-up cycleshape. Here, we present an experimental realization of such cycle-shaped waveforms and demonstrate control of the HHG process on the single-atom quantum level via attosecond steering of the electron trajectories. With our optimized optical cycles, we boost the field-ionization launching the electron trajectories, increase the subsequent field-to-electron energy transfer, and reduce the trajectory duration. We demonstrate, in realistic experimental conditions, two orders of magnitude enhancement of the generated XUV flux together with an increased spectral cutoff. This application, which is only one example of what can be achieved with cycle-shaped high-field light-waves, has farreaching implications for attosecond spectroscopy and molecular self-probing

Attosecond chirp-encoded dynamics of light nuclei Attosecond chirp-encoded dynamics of light nuclei

International audienceWe study the spectral phase of high-order harmonic emission as an observable for probing ultrafast nuclear dynamics after the ionization of a molecule. Using a strong-field approximation theory that includes nuclear dynamics, we relate the harmonic phase to the phase of the overlap integral of the nuclear wavefunctions of the initial neutral molecule and the molecular ion after an attosecond probe delay. We determine experimentally the group delay of the high harmonic emission from D 2 and H 2 molecules, which allows us to verify the relation between harmonic frequency and the attosecond delay. The small difference in the harmonic phase between H 2 and D 2 calculated theoretically is consistent with our experimental results

Gradient microfluidics enables rapid bacterial growth inhibition testing

Bacterial growth inhibition tests have become a standard measure of the adverse effects of inhibitors for a wide range of applications, such as toxicity testing in the medical and environmental sciences. However, conventional well-plate formats for these tests are laborious and provide limited information (often being restricted to an end-point assay). In this study, we have developed a microfluidic system that enables fast quantification of the effect of an inhibitor on bacteria growth and survival, within a single experiment. This format offers a unique combination of advantages, including long-term continuous flow culture, generation of concentration gradients, and single cell morphology tracking. Using Escherichia coli and the inhibitor amoxicillin as one model system, we show excellent agreement between an on-chip single cell-based assay and conventional methods to obtain quantitative measures of antibiotic inhibition (for example, minimum inhibition concentration). Furthermore, we show that our methods can provide additional information, over and above that of the standard well-plate assay, including kinetic information on growth inhibition and measurements of bacterial morphological dynamics over a wide range of inhibitor concentrations. Finally, using a second model system, we show that this chip-based systems does not require the bacteria to be labeled and is well suited for the study of naturally occurring species. We illustrate this using Nitrosomonas europaea, an environmentally important bacteria, and show that the chip system can lead to a significant reduction in the period required for growth and inhibition measurements (<4 days, compared to weeks in a culture flask)

Cefuroxime Pharmacokinetics in Pediatric Cardiovascular Surgery Patients Undergoing Cardiopulmonary Bypass

Objectives The objective of this study was to determine the pharmacokinetics of cefuroxime in children undergoing cardiopulmonary bypass (CPB) for cardiovascular surgery. Design A prospective study. Setting A tertiary pediatric teaching hospital. Participants Infants and children undergoing CPB were enrolled in the study. Intervention An initial dose (mean, 24.2 ± 1.6 mg/kg) of cefuroxime was administered before surgical incision, and a second dose (mean, 14.4 ± 7.9 mg/kg) was administered in the CPB prime solution. Serial blood samples were obtained before, during, and after the CPB process. Samples were shipped on dry ice to the analytic laboratory and concentrations determined by a validated high-performance liquid chromatography method. A 2-compartment pharmacokinetic model was fitted to the data using maximum a priori–Bayesian estimation, with weight as a covariate. Monte Carlo simulations of a single-dose (25 mg/kg pre-CPB) approach and a 2-dose (25 mg/kg pre- and 12.5-mg/kg prime solution dose) approach were performed. Measurements and Main Results Fifteen subjects (9 males/6 females) were enrolled in the study, with median (range) age and weight of 11 (3-34) months and 9.5 (4.5-15.4) kg, respectively. The median (range) duration of CPB was 136 (71-243) minutes. Median and range cefuroxime pharmacokinetic parameters were as follows: maximum concentration (Cmax) dose, 1: 328 (150-512) μg/mL; systemic clearance, 0.050 (0.041-0.058) L/h/kg; steady-state volume of distribution, 0.213 (0.081-0.423) L/kg; volume of distribution in the central compartment, 0.081 (0.046-0.162) L/kg; and elimination half-life, 3.76 (1.03-6.81) hours. The median 8-hour post–dose-simulated cefuroxime concentrations were 26.5 and 16.0 mg/L for the 2-dose and single-dose regimens, respectively. Conclusion Manufacturers recommend that pediatric doses of cefuroxime (25-50 mg/kg) can be used in infants and children undergoing CPB to maintain adequate serum concentrations for surgical-site infection prophylaxis. A second intraoperative dose, administered through the CPB circuit, provides no additional prophylactic advantage

Protein-coding variants implicate novel genes related to lipid homeostasis contributing to body-fat distribution.

Body-fat distribution is a risk factor for adverse cardiovascular health consequences. We analyzed the association of body-fat distribution, assessed by waist-to-hip ratio adjusted for body mass index, with 228,985 predicted coding and splice site variants available on exome arrays in up to 344,369 individuals from five major ancestries (discovery) and 132,177 European-ancestry individuals (validation). We identified 15 common (minor allele frequency, MAF ≥5%) and nine low-frequency or rare (MAF <5%) coding novel variants. Pathway/gene set enrichment analyses identified lipid particle, adiponectin, abnormal white adipose tissue physiology and bone development and morphology as important contributors to fat distribution, while cross-trait associations highlight cardiometabolic traits. In functional follow-up analyses, specifically in Drosophila RNAi-knockdowns, we observed a significant increase in the total body triglyceride levels for two genes (DNAH10 and PLXND1). We implicate novel genes in fat distribution, stressing the importance of interrogating low-frequency and protein-coding variants