Models and Strategies for Variants of the Job Shop Scheduling Problem

Recently, a variety of constraint programming and Boolean satisfiability approaches to scheduling problems have been introduced. They have in common the use of relatively simple propagation mechanisms and an adaptive way to focus on the most constrained part of the problem. In some cases, these methods compare favorably to more classical constraint programming methods relying on propagation algorithms for global unary or cumulative resource constraints and dedicated search heuristics. In particular, we described an approach that combines restarting, with a generic adaptive heuristic and solution guided branching on a simple model based on a decomposition of disjunctive constraints. In this paper, we introduce an adaptation of this technique for an important subclass of job shop scheduling problems (JSPs), where the objective function involves minimization of earliness/tardiness costs. We further show that our technique can be improved by adding domain specific information for one variant of the JSP (involving time lag constraints). In particular we introduce a dedicated greedy heuristic, and an improved model for the case where the maximal time lag is 0 (also referred to as no-wait JSPs).Comment: Principles and Practice of Constraint Programming - CP 2011, Perugia : Italy (2011

Kinetic DTI of the cervical spine: diffusivity changes in healthy subjects

Introduction The study aims to assess the influence of neck extension on water diffusivity within the cervical spinal cord. Methods IRB approved the study in 22 healthy volunteers. All subjects underwent anatomical MR and diffusion tensor imaging (DTI) at 1.5 T. The cervical cord was imaged in neutral (standard) position and extension. Segmental vertebral rotations were analyzed on sagittal T2-weighted images using the SpineView® software. Spinal cord diffusivity was measured in cross-sectional regions of interests at multiple levels (C1–C5). Results As a result of non-adapted coil geometry for spinal extension, 10 subjects had to be excluded. Image quality of the remaining 12 subjects was good without any deteriorating artifacts. Quantitative measurements of vertebral rotation angles and diffusion parameters showed good intra-rater reliability (ICC= 0.84–0.99). DTI during neck extension revealed significantly decreased fractional anisotropy (FA) and increased radial diffusivity (RD) at the C3 level and increased apparent diffusion coefficients (ADC) at the C3 and C4 levels (p < 0.01 Bonferroni corrected). The C3/C4 level corresponded to the maximal absolute change in segmental vertebral rotation between the two positions. The increase in RD correlated positively with the degree of global extension, i.e., the summed vertebral rotation angle between C1 and C5 (R= 0.77, p= 0.006). Conclusion Our preliminary results suggest that DTI can quantify changes in water diffusivity during cervical spine extension. The maximal differences in segmental vertebral rotation corresponded to the levels with significant changes in diffusivity (C3/C4). Consequently, kinetic DTI measurements may open new perspectives in the assessment of neural tissue under biomechanical constraint

Associations of lumbar scoliosis with presentation of suspected early axial spondyloarthritis

Objective: Scoliosis may impact the mechanical loading and cause secondary changes of the sacroiliac joints and lumbar spine. Our goal was to look how lumbar scoliosis modify the clinical and imaging-study in patients with recent-onset inflammatory back pain (IBP) suggesting axial spondyloarthritis (axSpA).Methods: Baseline weight-bearing lumbar-spine radiographs obtained in the DESIR cohort of patients aged 18-50 years and having IBP for at least 3 months but less than 3 years suggesting axSpA were studied. After training on scoliosis detection based on Cobb's angle>10 degrees plus Nash-Moe grade >= 1, readers blinded to patient data measured spine lumbar scoliosis, sacral horizontal angle, lumbosacral angle and lumbar lordosis on the radiograph of the lumbar and scored sacroiliitis on the radiograph of the pelvis. Baseline MRIs T1 and STIR of the lumbar spine and sacroiliac joints were evaluated for respectively degenerative changes and signs of axSpA.Results: Of the 360 patients (50.8% females) 88.7% had lumbar pain and 69.3% met ASAS criteria for axSpA. Mean Cobb's angle was 3.2 degrees +/- 5.0 degrees and 28 (7.7%) patients had lumbar scoliosis. No statistical differences were observed for radiographic sacroiliitis, MRI sacroiliitis, modified Stoke Ankylosing Spondylitis Spinal Score, Pfirmmann score, high-intensity zone, protrusion, extrusion, MODIC score between patients with and without scoliosis. In both groups, degenerative changes by MRI were rare and predominated at L4-L5 and L5-S1.Conclusion: In patients with early IBP suggesting axSpA, lumbar scoliosis was not associated with inflammatory or degenerative changes. (C) 2019 Elsevier Inc. All rights reserved.Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas

Core-Guided and Core-Boosted Search for CP

Peer reviewe

Ten-year follow-up of degenerative spinal lesions on radiographs and MRI in axial spondyloarthritis: results of the DESIR (DEvenir des spondylarthropathies indifférenciées récentes) cohort

ObjectivesTo investigate the occurrence of spinal degenerative lesions (DL)s in axial spondyloarthritis (axSpA) inception cohort in radiographs and MRI over 10 years (10Y), to assess their changes over time and factors associated with them.MethodsWhole spine MRI and cervical and lumbar spine radiographs at baseline/5Y/10Y of patients with axSpA from the DESIR cohort were assessed for DLs by three readers. For descriptive analyses, DLs were defined by agreement between >= 2/3 readers or using the average of their assessments, at the patient level (>= 1 lesion/patient). To assess the progression of DLs over time, we used multilevel generalised estimating equation models considering individual reader data.ResultsImaging was available for 330 patients (mean age 34 [9] years, 47% male). At baseline, 53% of patients had >= 1 DL on radiographs and 94% on MRI; 71% and 97% had DL at 10Y, respectively. The most frequent lesion on radiographs was disc height loss (baseline: 45% of patients, 10Y: 65%) and MRI disc degeneration (86%, 95%). Progression over time on radiographs was detected for osteophytes (change/Y: 2.34%, 95% CI: 1.92-2.75), disc height loss (1.37%, 0.95-1.80) and facet joint osteoarthritis (1.30%, 0.90-1.69) and on MRI for disc bulging/herniation (1.19%, 0.74-1.64), Modic type I (1.01%, 0.69-1.33) and II (0.94%, 0.66-1.22) lesions. We also observed a significant increase per year in the total number of DLs on radiographs (beta: 1.81, 1.48-2.14) and MRI (beta: 4.17, 3.49-4.84). Associated factors in both modalities were increasing BMI and bDMARDs exposure.ConclusionIn axSpA spinal DLs, though common, progress very slowly over 10Y. Faster progression is observed with increasing BMI and bDMARDs exposure (severe axSpA).Key PointsQuestionThe long-term evolution of spinal DLs in axSpA on radiographs and MRI, and the associated factors, is currently poorly understood.FindingsSpinal DLs, although common, progress slowly over 10Y, but in patients with a higher BMI or exposed to bDMARDs, the progression is faster.Clinical relevanceUnderstanding the progression of spinal DLs in axSpA helps to refine the interpretation of long-term imaging, limit diagnostic errors and optimise management strategies, particularly in patients with the highest risk of progression of these lesions.Key PointsQuestionThe long-term evolution of spinal DLs in axSpA on radiographs and MRI, and the associated factors, is currently poorly understood.FindingsSpinal DLs, although common, progress slowly over 10Y, but in patients with a higher BMI or exposed to bDMARDs, the progression is faster.Clinical relevanceUnderstanding the progression of spinal DLs in axSpA helps to refine the interpretation of long-term imaging, limit diagnostic errors and optimise management strategies, particularly in patients with the highest risk of progression of these lesions.Key PointsQuestionThe long-term evolution of spinal DLs in axSpA on radiographs and MRI, and the associated factors, is currently poorly understood.FindingsSpinal DLs, although common, progress slowly over 10Y, but in patients with a higher BMI or exposed to bDMARDs, the progression is faster.Clinical relevanceUnderstanding the progression of spinal DLs in axSpA helps to refine the interpretation of long-term imaging, limit diagnostic errors and optimise management strategies, particularly in patients with the highest risk of progression of these lesions.Pathophysiology and treatment of rheumatic disease

The longitudinal changes of BOLD response and cerebral hemodynamics from acute to subacute stroke. A fMRI and TCD study

<p>Abstract</p> <p>Background</p> <p>By mapping the dynamics of brain reorganization, functional magnetic resonance imaging MRI (fMRI) has allowed for significant progress in understanding cerebral plasticity phenomena after a stroke. However, cerebro-vascular diseases can affect blood oxygen level dependent (BOLD) signal. Cerebral autoregulation is a primary function of cerebral hemodynamics, which allows to maintain a relatively constant blood flow despite changes in arterial blood pressure and perfusion pressure. Cerebral autoregulation is reported to become less effective in the early phases post-stroke.</p> <p>This study investigated whether any impairment of cerebral hemodynamics that occurs during the acute and the subacute phases of ischemic stroke is related to changes in BOLD response.</p> <p>We enrolled six aphasic patients affected by acute stroke. All patients underwent a Transcranial Doppler to assess cerebral autoregulation (Mx index) and fMRI to evaluate the amplitude and the peak latency (time to peak-TTP) of BOLD response in the acute (i.e., within four days of stroke occurrence) and the subacute (i.e., between five and twelve days after stroke onset) stroke phases.</p> <p>Results</p> <p>As patients advanced from the acute to subacute stroke phase, the affected hemisphere presented a BOLD TTP increase (p = 0.04) and a deterioration of cerebral autoregulation (Mx index increase, p = 0.046). A similar but not significant trend was observed also in the unaffected hemisphere. When the two hemispheres were grouped together, BOLD TTP delay was significantly related to worsening cerebral autoregulation (Mx index increase) (Spearman's rho = 0.734; p = 0.01).</p> <p>Conclusions</p> <p>The hemodynamic response function subtending BOLD signal may present a delay in peak latency that arises as patients advance from the acute to the subacute stroke phase. This delay is related to the deterioration of cerebral hemodynamics. These findings suggest that remodeling the fMRI hemodynamic response function in the different phases of stroke may optimize the detection of BOLD signal changes.</p