Repetitive Production Research Articles

Timing and visual feedback constraints on repetitive finger force production

While much is known about sequential effects in motor timing, less is understood about whether movement parameters such as force show sequential dependencies. In this study, we examined the effect of timing constraints on repetitive unimanual force production sequences. Ten healthy participants produced a series of pinch grip forces in time to a metronome and to visually specified force amplitudes. Either visual feedback of force produced or the auditory metronome removed 10 s into the experimental trial, with participants performing continued responses for the remaining 20 s. In the continuation trials, a negative lag-1 autocorrelation in the inter-response intervals (IRIs) was observed as is commonly seen in motor timing tasks. However, removal of visual feedback resulted in a systematic increase in mean force output through the course of the trial, resulting in positive lag-1 autocorrelation values. An interaction was found between mean IRI and peak force (PF) magnitude, with greater force variability seen for the larger intervals. However, the imposition of dual force and timing constraints had no effect either on the underlying variability of the PF or on the IRIs. The results are discussed in the context of force and time being independently specified components of a generalized motor program.

Repetitive production of positron emitters using deuterons accelerated by multiterawatt laser pulses

Positron emitters (11)C, (13)N, and (15)O, which can be used in positron emission tomography, were produced using deuterons accelerated by irradiation of laser pulses approximately 70 TW in peak power and approximately 30 fs in duration with a repetition of 10 Hz during a period of as long as 200 s. Every laser pulse irradiates the fresh surface of a long strip of a solid-state thin film. Deuterons contained in the film are accelerated in the relativistic plasma induced by the pulse. The deuterons are repetitively incident on solid plates, which are placed near the film, to produce positron emitters by nuclear reactions. The radioactivities of the activated plates are measured after the termination of laser irradiation. In activation of graphite, boron-nitride, and melamine plates, the products had total activities of 64, 46, and 153 Bq, respectively. Contamination in the setup was negligible even after several thousands of laser shots. Our apparatus is expected to greatly contribute to the construction of a compact PET diagnostic system in the future.

Intractable Chronic Motor Tics Dramatically Respond to Clerodendrum inerme (L) Gaertn

Tics are characterized by involuntary, sudden, rapid, repetitive, nonrhythmic, stereotyped movements or phonic productions. Those who suffer from either motor or phonic tics, but not both, for more than 1 year are diagnosed with chronic tic disorder. Several pharmacological interventions have been proposed for the treatment of tic disorder. Dopamine D2 receptor blockers and dopamine depletors are thought to be the most effective ones clinically. However, such treatments are suboptimal in terms of effectiveness and side effects, such as body weight gain and extrapyramidal symptoms. We report on a 13-year-old girl, with chronic motor tic disorder refractory to multiple anti-tic therapies, who showed dramatic improvement and remission after taking the crude leaf extract of Clerodendrum inerme (L) Gaertn. No side effects were observed during a follow-up of more than 2 years. To the best of our knowledge, this is the first report on the anti-tic effect of Clerodendrum inerme.

A proposal for integrating production control and quality control

PurposeThe purpose of this paper is to present a practical proposal for integrating production control (PC) and quality control (QC) at the shop floor level.Design/methodology/approachThe proposed method is based on three principles which relate PC and QC at the shop floor level. The proposal is applied successfully at the world's largest pencil factory.FindingsThe results show that the proposed method contributes to improve four performance indicators related to PC and QC at the company studied: increase the average throughput in about 28.9 per cent; reduce the average value of work in process (WIP) in about 35.6 per cent, reduce the average lead time by about 45.4 per cent, and reduce the average defect rate by about 71.4 per cent.Research limitations/implicationsThe proposal (mainly because of principle III) is developed to be applied in repetitive production (RP) systems, i.e. environments characterized by low production volume and low product variety.Practical implicationsSome practical implications for industrial managers arises from this study: managers must consider the importance of integrated PC and QC functions in order to get better results concerning performance indicators such as throughput, WIP, lead time, and rejection rate; the materials flow simplification is a prerequisite for a lot of improvement initiatives at the shop floor level; the adequate choice of the production control system (PCS) is vital in order to get positive results regarding the performance indicators related to PC; the determination of the production pace (or rate) for a RP system must take account capacity restrictions and the influence of defect rate on production rate.Originality/valueThe paper is original in that it shows that the performance of the shop floor level can be improved by means of integrating PC and QC, by discussing and implementing a method which simplifies the material flow in the shop floor level, chooses the most adequate PCS and shows how the production rate influence on the rejection rate. Therefore, the paper is important for those which practice industrial management, more specifically on PC and QC functions.

Gestural intrusions in Taiwanese and English.

Kinematic studies of repetitive speech production tasks involving English sequences such as “cop top” have provided abundant evidence for gestural intrusion errors: errorful constrictions that are co‐produced with intended target constrictions (Pouplier and Goldstein, 2005; Goldstein et al., 2007). These intrusions have been analyzed as transitions to more dynamically stable coordination modes. This work investigates Taiwanese speakers’ production of similar repetitive sequences such as [kap tap]. If the speech sequences are planned and executed in Taiwanese in the same way as in English, similar patterns of intrusive speech errors should be observed. However, analysis of the kinematic data from three speakers shows that these effects in Taiwanese differ from those in English in a number of ways. A systematic comparison of Taiwanese and English intrusions is presented in terms of frequency of occurrence (much higher in Taiwanese), standard deviation of magnitude (smaller in Taiwanese), and temporal relationships to intended gestures. The results are discussed with respect to the language‐specific regularities of gestural coordination and their implications for the mode‐locking account of speech errors. [Work supported by NIH‐NIDCD DC008780.]

Kinetics of Repeat Propagation in the Microgene Polymerization Reaction

Repetitive DNA is a periodic copolymer with the intrinsic property of exponential propagation to longer repeats. Microgene polymerization reaction (MPR) is a model system in which a short nonrepetitive homo-duplex DNA evolves to multiple repetitive products during heat-cool cycles. The mechanism underlying this process involves staggered annealing of complementary DNA strands of variable lengths and polymerase-mediated filling-in of the generated overhangs. MPR is considered here as a process sharing common features with two polymerization types, chain-growth and step-growth, and significant distinctions from both types were highlighted. The involved reaction stages were formulated and a kinetic model was derived and tested experimentally. The model can quantitatively explain MPR propagation and be used as a good approximation for this phenomenon.

Fast and repetitive in-capillary production of [18F]FDG

The increasing demand for radiopharmaceuticals to be provided reproducibly and flexibly with high frequency for clinical application and animal imaging would be better met by improved or even new strategies for automated tracer production. Radiosynthesis in microfluidic systems, i.e. narrow tubing with a diameter of approximately 50-500 microm, holds promise for providing the means for repetitive multidose and multitracer production. In this study, the performance of a conceptually simple microfluidic device integrated into a fully automated synthesis procedure for in-capillary radiosynthesis (ICR) of clinical grade [(18)F]FDG was evaluated. The instrumental set-up consisted of pumps for reagent and solvent delivery into small mixing chambers, micro-fluidic capillaries, in-process radioactivity monitoring, solid-phase extraction and on-column deprotection of the (18)F-labelled intermediate followed by on-line formulation of [(18)F]FDG. In-capillary(18)F-fluorination of 2.1 micromol 1,3,4,6-tetra-O-acetyl-2-O-trifluoromethanesulphonyl-beta-D-mannopyranose (TATM; precursor for [(18)F]FDG) in acetonitrile (MeCN) at a flow rate of 0.3 ml/min within 40 s and subsequent on-line hydrolysis of the intermediate by treatment with 0.3 M NaOH for 1 min at 40 degrees C resulted in a radiochemical yield of 88 +/- 4% within <7 min. Reproducibility, robustness and suitability as a fast and efficient radiopharmaceutical research tool for (18)F-fluorination was demonstrated by eight independent, sequentially performed ICRs which provided identical tracer quality (radiochemical purity >97%, MeCN <5 microg/ml) and similar absolute yields (approximately 1.4 GBq). The described ICR process is a simple and efficient alternative to classic radiotracer production systems and provides a comparatively cheap instrumental methodology for the repetitive production of [(18)F]FDG with remarkably high efficiency and high yield under fully automated conditions. Although the results concerning the levels of activity need to be confirmed after installation of the equipment in a suitable GMP hot-cell environment, we expect the instrumental design to allow up-scaling without major difficulties or fundamental restrictions. Furthermore, we are convinced that similar or nearly identical procedures, and thus instrumentation, will allow ICR of other (18)F-labelled radiopharmaceuticals.

Operation and control of flow manufacturing based on constraints management for high-mix/low-volume production

The existing technology of flow manufacturing, which is mainly appropriate for high volume and repetitive production, is proven difficult to be applied in high-mix/low-volume environments. To adapt lean production into the latter, a new type of flow manufacturing is proposed based on flow path management technology. This paper first describes the general operation framework of the proposed new mode. The main idea is the dynamic formation of adaptable virtual production lines (called flow paths) corresponding to different product families. The application of different theories of constraints/drum-buffer-rope (TOC/DBR) control policies depends on the differences in scope of variety and scale of demand for these product families. The overall architecture of the proposed mechanism of constraint management-based operation and control is introduced. For the implementation, a mathematical programming method is suggested for the dynamic planning of flow paths, and a TOC/DBR ‘path-specific’ mechanism with group scheduling is used for the control over each flow path.We also study other critical issues including the identification and management of resource bottlenecks, and the setting of the buffer size in the deployment of the TOC/DBR mechanism.

Cobacabana (control of balance by card-based navigation): A card-based system for job shop control

Existing card-based production control systems such as Kanban are mostly dedicated to repetitive production environments. Cards-based systems for job shop control are lacking, while particularly this industry segment shows a need for simple control systems. This paper aims at filling the gap by presenting a simple card-based system for job shop control, the Cobacabana ( control of balance by card- based navigation) system. It is based on the concept of workload control (WLC), which has already proven its value in job shops. Developments towards more robust norms now allow for transforming the WLC concept into a simple card-based system, with loops of cards accompanying orders from release until completion at critical work centers. Cards returning from work centers authorize the planner to release new orders. A card-based display supports the planner with an overview of the shop floor situation, based on non-released cards. An additional loop of cards between sales and planning enables support of the order acceptance and due date promising function. A card-based acceptance display indicates what delivery dates are realistic, considering the current workload situation. Both the scientific roots of the system and practical implementation issues are discussed in this paper.

A GA optimization model for workgroup-based repetitive scheduling (WoRSM)

Most construction repetitive scheduling methods developed so far have been based on the premise that a repetitive project is comprised of many identical production units. Recently Huang and Sun [Huang RY, Sun KS. Non-unit based planning and scheduling of repetitive construction project. J Constr Eng Manage ASCE 2006;132(6):585–97] developed a workgroup-based repetitive scheduling method that takes the view that a repetitive construction project consists of repetitive activities of workgroups. Instead of repetitive production units, workgroups with repetitive or similar activities in a repetitive project are identified and employed in the planning and scheduling. The workgroup-based approach adds more flexibility to the planning and scheduling of repetitive construction projects and enhances the effectiveness of repetitive scheduling. This work builds on previous research and develops an optimization model for workgroup-based repetitive scheduling. A genetic algorithm (GA) is employed in model formation for finding the optimal solution. A chromosome representation, as well as specification of other parameters for GA analysis, is described in the paper. A sample case study is used for model validation and demonstration. Results and findings are reported.

Repetitive Production of Nanosecond Gigawatt Microwave Pulses

This paper presents the results of the theoretical and experimental studies of an efficient and stably operating microwave source with a nanosecond high-current electron beam in an extended backward-wave-oscillator-type slow-wave structure. The possibilities for stabilization of the RF field phase and for minimization of the pulse-to-pulse peak power spread have been demonstrated. Possible mechanisms of the stabilization of peak microwave power are considered, with emphasis placed on the mode in which a part of the particles are reflected in an intense RF field.

Phoneme-based rehabilitation of anomia in aphasia

This study investigated the effects of phonologic treatment for anomia in aphasia. We proposed that if treatment were directed at the level of the phonologic processor, opportunities for naming via a phonological route, as opposed to a strictly whole word route, would be enhanced, thereby improving naming. The participants, ten people with anomia and aphasia due to left hemisphere stroke, received 96 h of phoneme based treatment in 12 weeks. To learn if treatment improved naming, a single-subject, repeated probe design with replication was employed. The primary outcome measure was confrontation naming. Secondary outcome measures included phonologic production, nonword repetition and discourse production. Results suggest a positive treatment effect (confrontation naming), improvements in phonologic production and nonword repetition, and generalization to discourse production. When tested 3 months after the completion of treatment the effects appeared to be maintained.

The Impact of the Learning Curve in Laparoscopic Surgery

TP Wright originally introduced the concept of a learningcurve in aircraft manufacturing in 1936.1 He described a basic theoryfor costing the repetitive production of airplane assemblies. The termwas introduced to medicine in the 1980s after the advent of minimalaccess surgery. It also caught the attention of the public and the legalprofession when a surgeon told a public enquiry in Britain that a highdeath rate was inevitable while surgeons were on a learning curve.2Recently it has been labeled as a dangerous curve3 with a morbidity,mortality and unproven outcomes. Yet there is no standardization ofwhat the term means. In an endeavor to help laparoscopic surgeonstowards evidence based practices this commentary will define anddescribe the learning curve, its drawing followed by a discussion of thefactors affecting it, statistical evaluation, effect on randomized controlledtrials and clinical implications for both practice and training, thelimitations and pitfalls, ethical dilemmas and some thoughts to pavethe way ahead.

Conditional and marginal performance of the Poisson CUSUM control chart with parameter estimation

Cumulative Sum (CUSUM) type control charts are widely used in industry because of their effectiveness for process control. The Poisson CUSUM is a powerful and easy-to-implement control chart, which is appropriate for monitoring the counts of nonconformities in a unit from a repetitive production process. In the literature, control chart performances are generally evaluated under the assumption of known in-control process parameters. However, in-control process parameters are rarely known in practice and often parameter estimates from a reference sample are used instead. As a consequence of the additional variability introduced by parameter estimation, operational performance of a control chart might differ from the expected performance when the parameters are known. In this paper, effect of estimated process mean on the conditional and marginal performance of the Poisson CUSUM chart are quantified. The Markov Chain approach is used for calculating the aspects of the run length distribution. The effect of estimation on the in-control average run length performance is shown to be significant. Sample-size recommendations are provided.

Analysis of musculoskeletal loading in an index finger during tapping

Since musculoskeletal disorders of the upper extremities are believed to be associated with repetitive excessive muscle force production in the hands, understanding the time-dependent muscle forces during key tapping is essential for exploring the mechanisms of disease initiation and development. In the current study, we have simulated the time-dependent dynamic loading in the muscle/tendons in an index finger during tapping. The index finger model is developed using a commercial software package AnyBody, and it contains seven muscle/tendons that connect the three phalangeal finger sections. Our simulations indicate that the ratios of the maximal forces in flexor digitorum superficialis (FS) and flexor digitorum profundus (FP) tendons to the maximal force at the fingertip are 0.95 and 2.9, respectively, which agree well with recently published experimental data. The time sequence of the finger muscle activation predicted in the current study is consistent with the EMG data in the literature. The proposed model will be useful for bioengineers and ergonomic designers to improve keyboard design minimizing musculoskeletal loadings in the fingers.

Le jeu chez l’enfant victime d’événements traumatiques

Le jeu chez l’enfant victime d’événements traumatiques

Cyclic job scheduling in paced assembly lines with cross-trained workers

Paced or synchronous assembly lines allow concurrent manufacturing of a mix of products by repetitive production of a minimal product set (MPS). We refer to the associated production schedules as cyclic. We consider a paced assembly line where every job (or order) visits all m assembly stations in the same sequence and spends the same amount of time (known as the production cycle) at each station, by using the appropriate number of workers. Hence, associated with each job is an m-tuple of workforce requirements. Our objective is to find a cyclic schedule of jobs such that the total required workforce size is minimized. Assuming that each worker is cross-trained to work at a number of stations, we show that the problem is strongly NP-complete. In light of this result, we develop lower bounds, heuristic algorithms and an optimal branch-and-bound procedure. Our computational experiments show that our algorithms are computationally efficient and exhibit near-optimal performance. We also compare the savings in workforce size among systems with various levels of cross training.

An optimization model for workgroup-based repetitive scheduling

Most construction repetitive scheduling methods developed so far have been based on the premise that a repetitive project is comprised of many identical production units. Recently, Huang and Sun (2005) developed a workgroup-based repetitive scheduling method that takes the view that a repetitive construction project consists of repetitive activities of workgroups. Instead of repetitive production units, workgroups with repetitive or similar activities in a repetitive project are identified and employed in the planning and scheduling. The workgroup-based approach adds more flexibility to the planning and scheduling of repetitive construction projects and enhances the effectiveness of repetitive scheduling. This work builds on previous research and develops an optimization model for workgroup-based repetitive scheduling. A genetic algorithm (GA) is employed in model formation for finding the optimal or near-optimal solution. A chromosome representation, as well as specification of other parameters for GA analysis, is described in the paper. Two sample case studies, one simple and one sewer system project, are used for model validation and demonstration. Results and findings are reported.Key words: construction scheduling, repetitive project, workgroup, optimization, genetic algorithm.

An Analytical Strategy for Quaternary Ammonium Neuromuscular Blocking Agents in a Forensic Setting Using LC-MS/MS on a Tandem Quadrupole/Time-of-Flight Instrument

An analytical strategy is described for analyzing quaternary ammonium neuromuscular blocking agents in a wide variety of biological specimens in a forensic setting. Neuromuscular blocking agents such as succinylcholine, pancuronium, and tubocurarine, often used as paralytic agents during surgery, are occasionally suspected as paralytic poisoning agents involved in suspected homicide and suicide cases. Because suspicion in such cases can develop slowly, the age, nature, and quality of available specimens varies greatly. The compounds are challenging analytically because of their simultaneous precharged yet lipophilic character. An analytical strategy has been devised for extracting these compounds from complex matrices using a combination of a modified Bligh and Dyer liquid-liquid extraction (used in reverse) followed by reverse-phase ion pairing solid-phase extraction using heptafluorobutyric acid as an ion pairing reagent. Final analysis is by LC-MS/MS using a tandem quadrupole orthogonal acceleration time of flight instrument (Q-TOF) with repetitive product ion scanning at high resolution. Native and spiked specimens are compared for both quantitative and especially qualitative purposes. The method has been applied to a wide variety of fluid and tissue specimen types, including numerous specimens from exhumation autopsies. For most specimens, detection limits are in the 2 to 10 ng/g range. Succinylmonocholine has been demonstrated to be present at low levels in normal posthumous kidney and liver. The Q-TOF is an excellent platform for forensic analytical investigations. This analytical strategy should also be applicable to other problematic analytes and sample matrices.

Direct somatic embryogenesis and plant regeneration from leaf explants of Phalaenopsis amabilis

Leaf explants of Phalaenopsis amabilis var. formosa formed clusters of somatic embryos directly from epidermal cells without an intervening callus within 20 – 30 d when cultured on 1/2-strength modified Murashige and Skoog medium supplemented with 0.1, 1 and 3 mg dm−3 TDZ. Repetitive production of embryos involved secondary embryogenesis could be obtained by culturing segments of embryogenic masses on TDZ-containing media. Plantlet conversion from embryos was successfully achieved on regulator-free growth medium.