307 research outputs found

    Optimization of schedule stability and efficiency under processing time variability and random machine breakdowns in a job shop environment

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    The ability to cope with uncertainty in dynamic scheduling environments is becoming an increasingly important issue. In such environments, any disruption in the production schedule will translate into a disturbance of the plans for several external activities as well. Hence, from a practical point of view, deviations between the planned and realized schedules are to be avoided as much as possible. The term stability refers to this concern. We propose a proactive approach to generate efficient and stable schedules for a job shop subject to processing time variability and random machine breakdowns. In our approach, efficiency is measured by the makespan, and the stability measure is the sum of the variances of the realized completion times. Because the calculation of the original measure is mathematically intractable, we develop a surrogate stability measure. The version of the problem with the surrogate stability measure is proven to be NP-hard, even without machine breakdowns; a branch-and-bound algorithm is developed for this problem variant. A tabu search algorithm is proposed to handle larger instances of the problem with machine breakdowns. The results of extensive computational experiments indicate that the proposed algorithms are quite promising in performance. Copyright Β© 2011 Wiley Periodicals, Inc

    Direct Measurement of the System-Environment Coupling as a Tool For Understanding Decoherence and Dynamical Decoupling

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    Decoherence is a major obstacle to any practical implementation of quantum information processing. One of the leading strategies to reduce decoherence is dynamical decoupling --- the use of an external field to average out the effect of the environment. The decoherence rate under any control field can be calculated if the spectrum of the coupling to the environment is known. We present a direct measurement of the bath coupling spectrum in an ensemble of optically trapped ultracold atoms, by applying a spectrally narrow-band control field. The measured spectrum follows a Lorentzian shape at low frequencies, but exhibits non-monotonic features at higher frequencies due to the oscillatory motion of the atoms in the trap. These features agree with our analytical models and numerical Monte-Carlo simulations of the collisional bath. From the inferred bath-coupling spectrum, we predict the performance of well-known dynamical decoupling sequences: CPMG, UDD and CDD. We then apply these sequences in experiment and compare the results to predictions, finding good agreement in the weak-coupling limit. Thus, our work establishes experimentally the validity of the overlap integral formalism, and is an important step towards the implementation of an optimal dynamical decoupling sequence for a given measured bath spectrum.Comment: 9 pages, 6 figure

    The Supercooling of a Nematic Liquid Crystal

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    We investigate the supercooling of a nematic liquid crystal using fluctuating non-linear hydrodynamic equations. The Martin-Siggia-Rose formalism is used to calculate renormalized transport coefficients to one-loop order. Similar theories for isotropic liquids have shown substantial increases of the viscosities as the liquid is supercooled or compressed due to feedback from the density fluctuations which are freezing. We find similar results here for the longitudinal and various shear viscosities of the nematic. However, the two viscosities associated with the nematic director motion do not grow in any dramatic way; i.e.\ there is no apparent freezing of the director modes within this hydrodynamic formalism. Instead a glassy state of the nematic may arise from a ``random anisotropy" coupling of the director to the frozen density.Comment: Late

    Evaluation of the glycemic effect of methotrexate in psoriatic arthritis patients with metabolic syndrome. a pilot study

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    Methotrexate (MTX) is a systemic immunosuppressant drug used for the treatment of psoriasis and psoriatic arthritis. Previous studies demonstrated a potential association between psoriasis and diabetes mellitus, obesity, atherosclerosis, hypertension, eventuating into metabolic syndrome. This study aimed at exploring the glycemic effects of MTX in psoriatic arthritis (PsA) patients. In this prospective cross-sectional study, 27 patients with PsA were evaluated. The status of PsA and presence of accompanying metabolic syndrome was determined by standard criteria and indices. Blood indicators including HbA1c, erythrocyte sedimentation rate, fasting blood sugar, total cholesterol, high-density lipoprotein, triglycerides, and C-reactive protein were examined before and 12 weeks after MTX therapy. There were no significant changes between HbA1c levels before and after MTX therapy in both genders (men: P=0.131, women: P=0.803). In addition, HbA1c levels in PsA patients with metabolic syndrome were not different before and after treatment (P=0.250). Finally, HbA1c levels did not change in PsA patients without metabolic syndrome before and after therapy (P=0.506). MTX in PsA patients does not appear to have hyperglycaemic effects in the short-term and can be safely used in patients with metabolic syndrome and diabete

    Effects of maternal modafinil treatment on fetal development and neonatal growth parameters β€” a multicenter case series of the European Network of Teratology Information Services (ENITS)

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    \ua9 2023 The Authors. Acta Psychiatrica Scandinavica published by John Wiley & Sons Ltd.Objective: In recent years, safety concerns about modafinil exposure during pregnancy have emerged. In particular, increased risks for major congenital anomalies (MCA) and impaired fetal growth were reported, although study results were conflicting. Our investigation aims to examine previously reported safety signals. Method: Multicenter case series based on data from 18 Teratology Information Services from 12 countries. Modafinil exposed pregnancies with an estimated date of birth before August 2019 were included in this study. For prospectively ascertained pregnancies, cumulative incidences of pregnancy outcomes, rate of nonchromosomal MCA in first trimester exposed pregnancies and percentiles of neonatal/infant weight and head circumference (HC) were calculated. Potential dose-dependent effects on fetal growth were explored by linear regression models. Retrospectively ascertained cases were screened for pattern of MCA and other adverse events. Results: One hundred and seventy-five prospectively ascertained cases were included, of which 173 were exposed at least during the first trimester. Cumulative incidences for live birth, spontaneous abortion and elective termination of pregnancy were 76.9% (95% CI, 68.0%–84.8%), 9.3% (95% CI, 5.0%–16.9%), and 13.9% (95% CI, 8.1%–23.1%), respectively. Nonchromosomal MCA was present in 3/150 live births, corresponding to an MCA rate of 2.0% (95%CI, 0.6%–6.1%), none were reported in pregnancy losses. Compared to reference standards, birth weight (BW) tended to be lower and neonatal HC to be smaller in exposed newborns (data available for 144 and 73 of 153 live births, respectively). In nonadjusted linear regression models, each 100 mg increase of average dosage per pregnancy day was associated with a decrease in standard deviation score (SDS) of βˆ’0.28 SDS (95% CI, βˆ’0.45 to βˆ’0.10) for BW and of βˆ’0.28 SDS (95% CI, βˆ’0.56 to 0.01) for HC. Screening of 22 retrospectively reported cases did not reveal any specific pattern of MCA or other adverse outcomes. Conclusion: The results do not indicate an increased risk of MCA after in utero exposure to modafinil, but a tendency toward lower BW and reduced neonatal HC. However, these findings should be regarded as preliminary. Until further studies allow for a definite conclusion, modafinil should not be used during pregnancy

    Paper-based microfluidic system for tear electrolyte analysis

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    The analysis of tear constituents at point-of-care settings has a potential for early diagnosis of ocular disorders such as dry eye disease, low-cost screening, and surveillance of at-risk subjects. However, current minimally-invasive rapid tear analysis systems for point-of-care settings have been limited to assessment of osmolarity or inflammatory markers and cannot differentiate between dry eye subclassifications. Here, we demonstrate a portable microfluidic system that allows quantitative analysis of electrolytes in the tear fluid that is suited for point-of-care settings. The microfluidic system consists of a capillary tube for sample collection, a reservoir for sample dilution, and a paper-based microfluidic device for electrolyte analysis. The sensing regions are functionalized with fluorescent crown ethers, o-acetanisidide, and seminaphtorhodafluor that are sensitive to mono- and divalent electrolytes, and their fluorescence outputs are measured with a smartphone readout device. The measured sensitivity values of Na(+), K(+), Ca(2+) ions and pH in artificial tear fluid were matched with the known ion concentrations within the physiological range. The microfluidic system was tested with samples having different ionic concentrations, demonstrating the feasibility for the detection of early-stage dry eye, differential diagnosis of dry eye sub-types, and their severity staging

    Mind Perception: Real but Not Artificial Faces Sustain Neural Activity beyond the N170/VPP

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    Faces are visual objects that hold special significance as the icons of other minds. Previous researchers using event-related potentials (ERPs) have found that faces are uniquely associated with an increased N170/vertex positive potential (VPP) and a more sustained frontal positivity. Here, we examined the processing of faces as objects vs. faces as cues to minds by contrasting images of faces possessing minds (human faces), faces lacking minds (doll faces), and non-face objects (i.e., clocks). Although both doll and human faces were associated with an increased N170/VPP from 175–200 ms following stimulus onset, only human faces were associated with a sustained positivity beyond 400 ms. Our data suggest that the N170/VPP reflects the object-based processing of faces, whether of dolls or humans; on the other hand, the later positivity appears to uniquely index the processing of human facesβ€”which are more salient and convey information about identity and the presence of other minds

    Automated Workflow for Preparation of cDNA for Cap Analysis of Gene Expression on a Single Molecule Sequencer

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    Background: Cap analysis of gene expression (CAGE) is a 59 sequence tag technology to globally determine transcriptional starting sites in the genome and their expression levels and has most recently been adapted to the HeliScope single molecule sequencer. Despite significant simplifications in the CAGE protocol, it has until now been a labour intensive protocol. Methodology: In this study we set out to adapt the protocol to a robotic workflow, which would increase throughput and reduce handling. The automated CAGE cDNA preparation system we present here can prepare 96 β€˜HeliScope ready ’ CAGE cDNA libraries in 8 days, as opposed to 6 weeks by a manual operator.We compare the results obtained using the same RNA in manual libraries and across multiple automation batches to assess reproducibility. Conclusions: We show that the sequencing was highly reproducible and comparable to manual libraries with an 8 fold increase in productivity. The automated CAGE cDNA preparation system can prepare 96 CAGE sequencing samples simultaneously. Finally we discuss how the system could be used for CAGE on Illumina/SOLiD platforms, RNA-seq and fulllengt

    Foamy Macrophages from Tuberculous Patients' Granulomas Constitute a Nutrient-Rich Reservoir for M. tuberculosis Persistence

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    Tuberculosis (TB) is characterized by a tight interplay between Mycobacterium tuberculosis and host cells within granulomas. These cellular aggregates restrict bacterial spreading, but do not kill all the bacilli, which can persist for years. In-depth investigation of M. tuberculosis interactions with granuloma-specific cell populations are needed to gain insight into mycobacterial persistence, and to better understand the physiopathology of the disease. We have analyzed the formation of foamy macrophages (FMs), a granuloma-specific cell population characterized by its high lipid content, and studied their interaction with the tubercle bacillus. Within our in vitro human granuloma model, M. tuberculosis long chain fatty acids, namely oxygenated mycolic acids (MA), triggered the differentiation of human monocyte-derived macrophages into FMs. In these cells, mycobacteria no longer replicated and switched to a dormant non-replicative state. Electron microscopy observation of M. tuberculosis–infected FMs showed that the mycobacteria-containing phagosomes migrate towards host cell lipid bodies (LB), a process which culminates with the engulfment of the bacillus into the lipid droplets and with the accumulation of lipids within the microbe. Altogether, our results suggest that oxygenated mycolic acids from M. tuberculosis play a crucial role in the differentiation of macrophages into FMs. These cells might constitute a reservoir used by the tubercle bacillus for long-term persistence within its human host, and could provide a relevant model for the screening of new antimicrobials against non-replicating persistent mycobacteria
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