SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Process control

164

Although a number of leucine-rich repeat receptor-like kinase-encoding genes (LRR-RLKs) have been identified in plants, a functional role has been determined for only a few. Recent studies have demonstrated that an LRR-RLK, PXY/TDR, is important for the process of secondary vascular development. Other studies have indicated that PXY/TDR is unlikely to be the sole LRR-RLK involved in this complex process.

Concepts: Organism, Species, Process control

155

In many applications entanglement must be distributed through noisy communication channels that unavoidably degrade it. Entanglement cannot be generated by local operations and classical communication (LOCC), implying that once it has been distributed it is not possible to recreate it by LOCC. Recovery of entanglement by purely local control is however not forbidden in the presence of non-Markovian dynamics, and here we demonstrate in two all-optical experiments that such entanglement restoration can even be achieved on-demand. First, we implement an open-loop control scheme based on a purely local operation, without acquiring any information on the environment; then, we use a closed-loop scheme in which the environment is measured, the outcome controling the local operations on the system. The restored entanglement is a manifestation of “hidden” quantum correlations resumed by the local control. Relying on local control, both schemes improve the efficiency of entanglement sharing in distributed quantum networks.

Concepts: Environment, Natural environment, Experiment, Control theory, Control, Process control, Feed-forward, Open-loop controller

32

Our ability to predict species responses to environmental changes relies on accurate records of animal movement patterns. Continental-scale acoustic telemetry networks are increasingly being established worldwide, producing large volumes of information-rich geospatial data. During the last decade, the Integrated Marine Observing System’s Animal Tracking Facility (IMOS ATF) established a permanent array of acoustic receivers around Australia. Simultaneously, IMOS developed a centralised national database to foster collaborative research across the user community and quantify individual behaviour across a broad range of taxa. Here we present the database and quality control procedures developed to collate 49.6 million valid detections from 1891 receiving stations. This dataset consists of detections for 3,777 tags deployed on 117 marine species, with distances travelled ranging from a few to thousands of kilometres. Connectivity between regions was only made possible by the joint contribution of IMOS infrastructure and researcher-funded receivers. This dataset constitutes a valuable resource facilitating meta-analysis of animal movement, distributions, and habitat use, and is important for relating species distribution shifts with environmental covariates.

Concepts: Developed country, Quality control, Tracking, Process control, Geospatial, Wireless locating

28

The use of statistical process control (SPC) charts in healthcare is increasing. The general advice when plotting SPC charts is to begin by selecting the right chart. This advice, in the case of attribute data, may be limiting our insights into the underlying process and consequently be potentially misleading. Given the general lack of awareness that additional insights may be obtained by using more than one SPC chart, there is a need to review this issue and make some recommendations. Under purely common cause variation the control limits on the xmr-chart and traditional attribute charts (eg, p-chart, c-chart, u-chart) will be in close agreement, indicating that the observed variation (xmr-chart) is consistent with the underlying Binomial model (p-chart) or Poisson model (c-chart, u-chart). However, when there is a material difference between the limits from the xmr-chart and the attribute chart then this also constitutes a signal of an underlying systematic special cause of variation. We use one simulation and two case studies to demonstrate these ideas and show the utility of plotting the SPC chart for attribute data alongside an xmr-chart. We conclude that the combined use of attribute charts and xmr-charts, which requires little additional effort, is a useful strategy because it is less likely to mislead us and more likely to give us the insight to do the right thing.

Concepts: Scientific method, Control theory, Process control, Control system, Control engineering, Conservatism, Control chart, Statistical process control

28

Alcohol-related stimuli attract social drinkers' attention (attentional bias). We devised a dual task to test whether attentional biases to alcohol-related stimuli are modulated by cognitive control mechanisms. Sixteen nondependent healthy social drinkers were required to respond to the direction of a central arrow (target) and to ignore adjacent congruent (low cognitive load) or incongruent (high cognitive load) distracting arrows (flankers) in the presence of alcohol-related, neutral or plain grey backgrounds. Percentages of correct responses to the target and reaction time of correct responses (latency) were recorded. The difference score of the flanker effect (latency incongruent-latency congruent) between trials when backgrounds were alcohol-related relative to when they were neutral was also computed. Latencies increased in the presence of the alcohol-related images relative to both the neutral and the grey displays, but only under high cognitive load. Response accuracy did not show this significant difference. The flanker effect difference score correlated positively with the participants' average weekly alcohol intake. The data suggest that the presence of alcohol-associated stimuli attenuates cognitive control processes in social drinkers, an effect that was associated with the participants' average weekly alcohol intake.

Concepts: Psychology, Attention, Cognitive bias, Working memory, Process control, Bias, Attention span, Lol Tolhurst

27

Reviewers play a key role in science, although studies suggest the current peer-reviewing system has faults. We propose to introduce a quality control system to evaluate each journal’s review process, and produce a Review Quality Index. We propose four schemes that have the potential to reduce errors in a key step in scientific decision making: the reviewing process.

Concepts: Scientific method, Quality control, Management, Control theory, Peer review, Process control, Control system, Control engineering

27

In this whitepaper, the Manufacturing Technical Committee of the Product Quality Research Institute provides information on the common, best practices in use today in the development of high-quality chemistry, manufacturing and controls documentation. Important topics reviewed include International Conference on Harmonization, in vitro-in vivo correlation considerations, quality-by-design approaches, process analytical technologies and current scale-up, and process control and validation practices. It is the hope and intent that this whitepaper will engender expanded dialog on this important subject by the pharmaceutical industry and its regulatory bodies.

Concepts: Management, Control theory, Automation, Process control, Control system, Controller, Control engineering, Gavin Rossdale

27

Semantic cognition requires a combination of semantic representations and executive control processes to direct activation in a task- and time-appropriate fashion [Jefferies, E., & Lambon Ralph, M. A. Semantic impairment in stroke aphasia versus semantic dementia: A case-series comparison. Brain, 129, 2132-2147, 2006]. We undertook a formal meta-analysis to investigate which regions within the large-scale semantic network are specifically associated with the executive component of semantic cognition. Previous studies have described in detail the role of left ventral pFC in semantic regulation. We examined 53 studies that contrasted semantic tasks with high > low executive requirements to determine whether cortical regions beyond the left pFC show the same response profile to executive semantic demands. Our findings revealed that right pFC, posterior middle temporal gyrus (pMTG) and dorsal angular gyrus (bordering intraparietal sulcus) were also consistently recruited by executively demanding semantic tasks, demonstrating patterns of activation that were highly similar to the left ventral pFC. These regions overlap with the lesions in aphasic patients who exhibit multimodal semantic impairment because of impaired regulatory control (semantic aphasia)-providing important convergence between functional neuroimaging and neuropsychological studies of semantic cognition. Activation in dorsal angular gyrus and left ventral pFC was consistent across all types of executive semantic manipulation, regardless of whether the task was receptive or expressive, whereas pMTG activation was only observed for manipulation of control demands within receptive tasks. Second, we contrasted executively demanding tasks tapping semantics and phonology. Our findings revealed substantial overlap between the two sets of contrasts within left ventral pFC, suggesting this region underpins domain-general control mechanisms. In contrast, we observed relative specialization for semantic control within pMTG as well as the most ventral aspects of left pFC (BA 47), consistent with our proposal of a distributed network underpinning semantic control.

Concepts: Cerebral cortex, Temporal lobe, Cerebrum, Superior temporal gyrus, Wernicke's area, Process control, Executive functions, Aphasia

26

To obtain high dynamic performance on induction motor drives (IMD), variable voltage and variable frequency operation has to be performed by measuring speed of rotation and stator currents through sensors and fed back them to the controllers. When the sensors are undergone a fault, the stability of control system, may be designed for an industrial process, is disturbed. This paper studies the negative effects on a 12.5 hp induction motor drives when the field oriented control system is subjected to sensor faults. To illustrate the importance of this study mine hoist load diagram is considered as shaft load of the tested machine. The methods to recover the system from sensor faults are discussed. In addition, the various speed sensorless schemes are reviewed comprehensively.

Concepts: Signal processing, Control theory, Feedback, Process control, Control system, Control engineering, Electric motor, Variable-frequency drive

25

The “Gate Control Theory of Pain” of 1965 became famous for integrating clinical observations and the understanding of spinal dorsal horn circuitry at that time into a testable model. While it became rapidly clear that spinal circuitry is much more complex than proposed by Melzack and Wall, their prediction of the clinical efficacy of transcutaneous electrical nerve stimulation (TENS) and spinal cord stimulation (SCS) has left an important clinical legacy also 50 years later. In the meantime it has been recognized that the sensitivity of the nociceptive system can be decreased or increased, and that this “gain control” can occur at peripheral, spinal and supraspinal levels. The resulting changes in pain sensitivity can be rapidly reversible or persistent, highly localized or widespread. Profiling of spatio-temporal characteristics of altered pain sensitivity (evoked pain to mechanical and/or heat stimuli) allows implications on the mechanisms likely active in a given patient, including peripheral or central sensitization, intraspinal or descending inhibition. This hypothesis generation in the diagnostic process is an essential step towards a mechanism-based treatment of pain. The challenge now is to generate the rational basis of multimodal pain therapy algorithms by including profile-based stratification of patients into studies on efficacy of pharmacological and non-pharmacological treatment modalities. This review outlines the current evidence base for this approach.

Concepts: Scientific method, Mathematics, Pain, Hypothesis, Control theory, Process control, PID controller, Control engineering