160 research outputs found
Flow shop scheduling with earliness, tardiness and intermediate inventory holding costs
We consider the problem of scheduling customer orders in a flow shop with the objective of minimizing the sum of tardiness, earliness (finished goods inventory holding) and intermediate (work-in-process) inventory holding costs. We formulate this problem as an integer program, and based on approximate solutions to two di erent, but closely related, Dantzig-Wolfe reformulations, we develop heuristics to minimize the total cost. We exploit the duality between Dantzig-Wolfe reformulation and Lagrangian relaxation to enhance our heuristics. This combined approach enables us to develop two di erent lower bounds on the optimal integer solution, together with intuitive approaches for obtaining near-optimal feasible integer solutions. To the best of our knowledge, this is the first paper that applies column generation to a scheduling problem with di erent types of strongly NP-hard pricing problems which are solved heuristically. The computational study demonstrates that our algorithms have a significant speed advantage over alternate methods, yield good lower bounds, and generate near-optimal feasible integer solutions for problem instances with many machines and a realistically large number of jobs
Downscaling the consolidation of goods – state of the art and transferability of micro-consolidation initiatives
Consolidation schemes are a popular measure in city logistics. The most common of
these consolidation schemes
are Urban Consolidation Centres (UCCs). However, many innovative experiences have been performed in the
cities across the globe, offering a large panel of alternative schemes. In particular, many experiences have
focused on down
scaling the consolidation effort by bundling the goods much closer to the reception point.
This paper aims in offering a closer view into different alternatives that exist regarding the physical micro
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consolidation of goods and to provide guidelines on se
lecting the most appropriate solutions for a specific city
area.
In order to do this, we will develop a transferability methodology, based on the study of case studies across the
Europe. We will build on the current transferability methodologies developed
under several EU projects and
adjust them for the specific case of the micro
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consolidation measures. This will lead us to the definition of the
most important features for the transferability of the micro
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consolidation measures. Based on this, we will
est
ablish for each feature a list of
attributes
for the transferability of the micro
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consolidation devices, which will
be prioritized according to their importance for the transferability success
Differences in efficacy of monepantel, derquantel and abamectin against multi-resistant nematodes of sheep
Drug resistance has become a global phenomenon in gastrointestinal nematodes of sheep, particularly resistance to macrocyclic lactones. New anthelmintics are urgently needed for both the control of infections with multi-resistant nematodes in areas where classical anthelmintics are no longer effective, and the prevention of the spread of resistance in areas where the problem is not as severe. Recently, two new active ingredients became commercially available for the treatment of nematode infections in sheep, monepantel (Zolvix®) and derquantel, the latter used only in a formulated combination with the macrocyclic lactone, abamectin (Startect®). In order to assess the potential of the new actives for the control and prevention of spread of anthelmintic resistance, two characterized multi-resistant field isolates from Australia were used in a GLP (good laboratory practice) conducted efficacy study in sheep. Eight infected sheep in each group were treated orally according to the product labels with 2.5 mg/kg body weight monepantel, 0.2 mg/kg abamectin, or with the combination of 2.0 mg/kg derquantel and 0.2 mg/kg abamectin. The results demonstrate that monepantel was fully effective against multi-resistant species, Trichostrongylus colubriformis and Haemonchus contortus (99.9%). In contrast, the combination of derquantel and abamectin was effective against T. colubriformis (99.9%), but was not effective against larval stages of the barber's pole worm H. contortus (18.3%)
A linear programming-based method for job shop scheduling
We present a decomposition heuristic for a large class of job shop scheduling problems. This heuristic utilizes information from the linear programming formulation of the associated optimal timing problem to solve subproblems, can be used for any objective function whose associated optimal timing problem can be expressed as a linear program (LP), and is particularly effective for objectives that include a component that is a function of individual operation
completion times. Using the proposed heuristic framework, we address job shop scheduling problems with a variety of objectives where intermediate holding costs need to be explicitly considered. In computational testing, we demonstrate the performance of our proposed solution approach
Recent advances in candidate-gene and whole-genome approaches to the discovery of anthelmintic resistance markers and the description of drug/receptor interactions
Anthelmintic resistance has a great impact on livestock production systems
worldwide, is an emerging concern in companion animal medicine, and represents
a threat to our ongoing ability to control human soil-transmitted helminths.
The Consortium for Anthelmintic Resistance and Susceptibility (CARS) provides
a forum for scientists to meet and discuss the latest developments in the
search for molecular markers of anthelmintic resistance. Such markers are
important for detecting drug resistant worm populations, and indicating the
likely impact of the resistance on drug efficacy. The molecular basis of
resistance is also important for understanding how anthelmintics work, and how
drug resistant populations arise. Changes to target receptors, drug efflux and
other biological processes can be involved. This paper reports on the CARS
group meeting held in August 2013 in Perth, Australia. The latest knowledge on
the development of molecular markers for resistance to each of the principal
classes of anthelmintics is reviewed. The molecular basis of resistance is
best understood for the benzimidazole group of compounds, and we examine
recent work to translate this knowledge into useful diagnostics for field use.
We examine recent candidate-gene and whole-genome approaches to understanding
anthelmintic resistance and identify markers. We also look at drug
transporters in terms of providing both useful markers for resistance, as well
as opportunities to overcome resistance through the targeting of the
transporters themselves with inhibitors. Finally, we describe the tools
available for the application of the newest high-throughput sequencing
technologies to the study of anthelmintic resistance
Influence of Genetic Background and Tissue Types on Global DNA Methylation Patterns
Recent studies have shown a genetic influence on gene expression variation, chromatin, and DNA methylation. However, the effects of genetic background and tissue types on DNA methylation at the genome-wide level have not been characterized extensively. To study the effect of genetic background and tissue types on global DNA methylation, we performed DNA methylation analysis using the Affymetrix 500K SNP array on tumor, adjacent normal tissue, and blood DNA from 30 patients with esophageal squamous cell carcinoma (ESCC). The use of multiple tissues from 30 individuals allowed us to evaluate variation of DNA methylation states across tissues and individuals. Our results demonstrate that blood and esophageal tissues shared similar DNA methylation patterns within the same individual, suggesting an influence of genetic background on DNA methylation. Furthermore, we showed that tissue types are important contributors of DNA methylation states
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Cross-tissue methylomic profiling strongly implicates a role for cortex-specific deregulation of ANK1 in Alzheimer’s disease neuropathology
Alzheimer’s disease (AD) is a chronic neurodegenerative disorder characterized by progressive neuropathology and cognitive decline. We describe a cross-tissue analysis of methylomic variation in AD using samples from three independent human post-mortem brain cohorts. We identify a differentially methylated region in the ankyrin 1 (ANK1) gene that is associated with neuropathology in the entorhinal cortex, a primary site of AD manifestation. This region was confirmed as significantly hypermethylated in two other cortical regions (superior temporal gyrus and prefrontal cortex) but not in the cerebellum, a region largely protected from neurodegeneration in AD, nor whole blood obtained pre-mortem, from the same individuals. Neuropathology-associated ANK1 hypermethylation was subsequently confirmed in cortical samples from three independent brain cohorts. This study represents the first epigenome-wide association study (EWAS) of AD employing a sequential replication design across multiple tissues, and highlights the power of this approach for identifying methylomic variation associated with complex disease
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