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Sample records for homeostatic gain control

  1. Human Homeostatic Control Matrix in Norm

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    Alexander G. Kruglov

    2016-09-01

    Full Text Available We undertook our research to study and systemize the relationship between hemodynamics and biochemical parameters of arterial and venous blood in healthy people. Hemodynamic and biochemical characteristics were obtained through a probe by using catheterization in various vascular areas (aorta, brain, heart, lungs, and liver. Correlation and factor analyses were conducted to study the relationship between the obtained characteristics of the regional and systemic blood flow. Due to the nature of the correlation analysis, the significant (p<0.05 relation signs (+, 0, - without regard to their power were considered. The obtained results suggested that there are sets of both intra-organ and system regulatory relationships between metabolic and hemodynamic characteristics. The complex of relationships among the studied parameters makes it possible to maintain the homeostatic equilibrium in the body. The psychophysiological control system includes the subsystems we described: 1 the cardiac-hepatic-pulmonary complex having properties of the metabolic and hemodynamic information field providing biological stability of the homeostasis; any significant imbalance of its elements triggers afferent information flows actualizing an afferent synthesis; 2 the mind forming gradient patterns of targeted behavior to eliminate metabolic imbalance, to achieve goals both as coded biological parameters and as the highest forms of behavior, to reach the ultimate goal: parametric, homeostatic equilibrium in the “biosphere” of the human body. By using the results of our research and the complex of dynamic relationships in human homeostasis, we built a homeostatic control matrix (HCM.

  2. Gaining control

    NARCIS (Netherlands)

    Enden, van der E.; Laan, van der R.

    2008-01-01

    The article reports on the efforts of companies to find a solution for tax risk management, tax accounting and being in control. In trying to find a solution, companies work towards an integrated tax control framework (TCF), a tax risk management and control environment embedded in the internal cont

  3. Gaining control

    NARCIS (Netherlands)

    Enden, van der E.; Laan, van der R.

    2008-01-01

    The article reports on the efforts of companies to find a solution for tax risk management, tax accounting and being in control. In trying to find a solution, companies work towards an integrated tax control framework (TCF), a tax risk management and control environment embedded in the internal cont

  4. Gaining control

    NARCIS (Netherlands)

    Enden, van der E.; Laan, van der R.

    2008-01-01

    The article reports on the efforts of companies to find a solution for tax risk management, tax accounting and being in control. In trying to find a solution, companies work towards an integrated tax control framework (TCF), a tax risk management and control environment embedded in the internal

  5. Robust concentration and frequency control in oscillatory homeostats.

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    Kristian Thorsen

    Full Text Available Homeostatic and adaptive control mechanisms are essential for keeping organisms structurally and functionally stable. Integral feedback is a control theoretic concept which has long been known to keep a controlled variable A robustly (i.e. perturbation-independent at a given set-point A(set by feeding the integrated error back into the process that generates A. The classical concept of homeostasis as robust regulation within narrow limits is often considered as unsatisfactory and even incompatible with many biological systems which show sustained oscillations, such as circadian rhythms and oscillatory calcium signaling. Nevertheless, there are many similarities between the biological processes which participate in oscillatory mechanisms and classical homeostatic (non-oscillatory mechanisms. We have investigated whether biological oscillators can show robust homeostatic and adaptive behaviors, and this paper is an attempt to extend the homeostatic concept to include oscillatory conditions. Based on our previously published kinetic conditions on how to generate biochemical models with robust homeostasis we found two properties, which appear to be of general interest concerning oscillatory and homeostatic controlled biological systems. The first one is the ability of these oscillators ("oscillatory homeostats" to keep the average level of a controlled variable at a defined set-point by involving compensatory changes in frequency and/or amplitude. The second property is the ability to keep the period/frequency of the oscillator tuned within a certain well-defined range. In this paper we highlight mechanisms that lead to these two properties. The biological applications of these findings are discussed using three examples, the homeostatic aspects during oscillatory calcium and p53 signaling, and the involvement of circadian rhythms in homeostatic regulation.

  6. Asthma Triggers: Gain Control

    Science.gov (United States)

    ... Search Asthma Contact Us Share Asthma Triggers: Gain Control Breathing Freely: Controlling Asthma Triggers This video features ... Air Quality: Biological Pollutants Help Your Child Gain Control Over Asthma Top of Page Molds About Molds ...

  7. Digital automatic gain control

    Science.gov (United States)

    Uzdy, Z.

    1980-01-01

    Performance analysis, used to evaluated fitness of several circuits to digital automatic gain control (AGC), indicates that digital integrator employing coherent amplitude detector (CAD) is best device suited for application. Circuit reduces gain error to half that of conventional analog AGC while making it possible to automatically modify response of receiver to match incoming signal conditions.

  8. Dynamic Networks of Human Homeostatic Control in Norm

    Directory of Open Access Journals (Sweden)

    Veronica A. Sherman

    2016-06-01

    Full Text Available The research has been undertaken to study the regional and common relationships between hemodynamic and metabolic parameters of human body functioning in individuals without clinical signs of pathology (in "norm". Indicators of hemodynamics and metabolism were obtained by catheterization in a variety of areas: LV, RV, RA, CS, Ao, fixed SS, IJV, SVC, right VH, renal vena, and PA. Correlation and factor analyses were conducted for the study of: 1 the relationship between biochemical parameters in the blood stream, 2 the relationship between hemodynamic parameters, 3 relationship between the hemodynamic and biochemical parameters. Due to the nature of the correlation analysis, the significant (p<0.05 relation signs (+, 0, - without regard to their power were considered. The obtained results in the study of brain blood flow, heart, liver, lungs, kidneys suggested the existence of the primary homeostatic control of the factors determining rheological and thrombogenic properties of blood; the regulation of brain gas exchange and intracranial venous pressure by the minimum level of pressure in the cerebral outflow pathway—the pressure in RA; the regulating relationships between blood flow in CS with blood flow in HV, RA, SS, and LV; and the existence of a synergistic complex of the relationships between the studied biochemical and hemodynamic characteristics that form the human homeostasis control matrix in norm.

  9. Commutated automatic gain control system

    Science.gov (United States)

    Yost, S. R.

    1982-01-01

    The commutated automatic gain control (AGC) system was designed and built for the prototype Loran-C receiver is discussed. The current version of the prototype receiver, the Mini L-80, was tested initially in 1980. The receiver uses a super jolt microcomputer to control a memory aided phase loop (MAPLL). The microcomputer also controls the input/output, latitude/longitude conversion, and the recently added AGC system. The AGC control adjusts the level of each station signal, such that the early portion of each envelope rise is about at the same amplitude in the receiver envelope detector.

  10. Brown-adipose-tissue macrophages control tissue innervation and homeostatic energy expenditure.

    Science.gov (United States)

    Wolf, Yochai; Boura-Halfon, Sigalit; Cortese, Nina; Haimon, Zhana; Sar Shalom, Hadas; Kuperman, Yael; Kalchenko, Vyacheslav; Brandis, Alexander; David, Eyal; Segal-Hayoun, Yifat; Chappell-Maor, Louise; Yaron, Avraham; Jung, Steffen

    2017-06-01

    Tissue macrophages provide immunological defense and contribute to the establishment and maintenance of tissue homeostasis. Here we used constitutive and inducible mutagenesis to delete the nuclear transcription regulator Mecp2 in macrophages. Mice that lacked the gene encoding Mecp2, which is associated with Rett syndrome, in macrophages did not show signs of neurodevelopmental disorder but displayed spontaneous obesity, which was linked to impaired function of brown adipose tissue (BAT). Specifically, mutagenesis of a BAT-resident Cx3Cr1(+) macrophage subpopulation compromised homeostatic thermogenesis but not acute, cold-induced thermogenesis. Mechanistically, malfunction of BAT in pre-obese mice with mutant macrophages was associated with diminished sympathetic innervation and local titers of norepinephrine, which resulted in lower expression of thermogenic factors by adipocytes. Mutant macrophages overexpressed the signaling receptor and ligand PlexinA4, which might contribute to the phenotype by repulsion of sympathetic axons expressing the transmembrane semaphorin Sema6A. Collectively, we report a previously unappreciated homeostatic role for macrophages in the control of tissue innervation. Disruption of this circuit in BAT resulted in metabolic imbalance.

  11. Homeostatic control of synaptic activity by endogenous adenosine is mediated by adenosine kinase.

    Science.gov (United States)

    Diógenes, Maria José; Neves-Tomé, Raquel; Fucile, Sergio; Martinello, Katiuscia; Scianni, Maria; Theofilas, Panos; Lopatár, Jan; Ribeiro, Joaquim A; Maggi, Laura; Frenguelli, Bruno G; Limatola, Cristina; Boison, Detlev; Sebastião, Ana M

    2014-01-01

    Extracellular adenosine, a key regulator of neuronal excitability, is metabolized by astrocyte-based enzyme adenosine kinase (ADK). We hypothesized that ADK might be an upstream regulator of adenosine-based homeostatic brain functions by simultaneously affecting several downstream pathways. We therefore studied the relationship between ADK expression, levels of extracellular adenosine, synaptic transmission, intrinsic excitability, and brain-derived neurotrophic factor (BDNF)-dependent synaptic actions in transgenic mice underexpressing or overexpressing ADK. We demonstrate that ADK: 1) Critically influences the basal tone of adenosine, evaluated by microelectrode adenosine biosensors, and its release following stimulation; 2) determines the degree of tonic adenosine-dependent synaptic inhibition, which correlates with differential plasticity at hippocampal synapses with low release probability; 3) modulates the age-dependent effects of BDNF on hippocampal synaptic transmission, an action dependent upon co-activation of adenosine A2A receptors; and 4) influences GABAA receptor-mediated currents in CA3 pyramidal neurons. We conclude that ADK provides important upstream regulation of adenosine-based homeostatic function of the brain and that this mechanism is necessary and permissive to synaptic actions of adenosine acting on multiple pathways. These mechanistic studies support previous therapeutic studies and implicate ADK as a promising therapeutic target for upstream control of multiple neuronal signaling pathways crucial for a variety of neurological disorders.

  12. Homeostatic Control of the Thyroid Pituitary Axis: Perspectives for Diagnosis and Treatment

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    Rudolf eHoermann

    2015-11-01

    Full Text Available The long-held concept of a proportional negative feedback control between the thyroid and pituitary gland requires reconsideration in the light of more recent studies. Homeostatic equilibria depend on dynamic interrelationships between thyroid hormones and pituitary thyrotropin (TSH. They display a high degree of individuality, thyroid-state-related hierarchy and adaptive conditionality. Molecular mechanisms involve multiple feedback loops on several levels of organization, different time scales and varying conditions of their optimum operation, including a proposed feedforward motif. This supports the concept of a dampened response and multistep regulation, making the interactions between TSH, FT4 and FT3 situational and mathematically more complex. As a homeostatically integrated parameter, TSH becomes neither normatively fixed nor a precise marker of euthyroidism. This is exemplified by the therapeutic situation with L-thyroxine (L-T4 where TSH levels defined for optimum health may not apply equivalently during treatment. In particular, an FT3-FT4 dissociation, discernible FT3-TSH disjoint and conversion inefficiency have been recognised in L-T4-treated athyreotic patients. In addition to regulating T4 production, TSH appears to play an essential role in maintaining T3 homeostasis by directly controlling deiodinase activity. While still allowing for tissue-specific variation this questions the currently assumed independence of the local T3 supply. Rather it integrates peripheral and central elements into an overarching control system. On L-T4 treatment, altered equilibria have been shown to give rise to lower circulating FT3 concentrations in the presence of normal serum TSH. While data on T3 in tissues are largely lacking in humans, rodent models suggest that the disequilibria may reflect widespread T3 deficiencies at the tissue level in various organs.As a consequence, the use of TSH, valuable though it is in many situations, should be

  13. Turing mechanism for homeostatic control of synaptic density during C. elegans growth

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    Brooks, Heather A.; Bressloff, Paul C.

    2017-07-01

    We propose a mechanism for the homeostatic control of synapses along the ventral cord of Caenorhabditis elegans during development, based on a form of Turing pattern formation on a growing domain. C. elegans is an important animal model for understanding cellular mechanisms underlying learning and memory. Our mathematical model consists of two interacting chemical species, where one is passively diffusing and the other is actively trafficked by molecular motors, which switch between forward and backward moving states (bidirectional transport). This differs significantly from the standard mechanism for Turing pattern formation based on the interaction between fast and slow diffusing species. We derive evolution equations for the chemical concentrations on a slowly growing one-dimensional domain, and use numerical simulations to demonstrate the insertion of new concentration peaks as the length increases. Taking the passive component to be the protein kinase CaMKII and the active component to be the glutamate receptor GLR-1, we interpret the concentration peaks as sites of new synapses along the length of C. elegans, and thus show how the density of synaptic sites can be maintained.

  14. A polarised population of dynamic microtubules mediates homeostatic length control in animal cells.

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    Remigio Picone

    Full Text Available Because physical form and function are intimately linked, mechanisms that maintain cell shape and size within strict limits are likely to be important for a wide variety of biological processes. However, while intrinsic controls have been found to contribute to the relatively well-defined shape of bacteria and yeast cells, the extent to which individual cells from a multicellular animal control their plastic form remains unclear. Here, using micropatterned lines to limit cell extension to one dimension, we show that cells spread to a characteristic steady-state length that is independent of cell size, pattern width, and cortical actin. Instead, homeostatic length control on lines depends on a population of dynamic microtubules that lead during cell extension, and that are aligned along the long cell axis as the result of interactions of microtubule plus ends with the lateral cell cortex. Similarly, during the development of the zebrafish neural tube, elongated neuroepithelial cells maintain a relatively well-defined length that is independent of cell size but dependent upon oriented microtubules. A simple, quantitative model of cellular extension driven by microtubules recapitulates cell elongation on lines, the steady-state distribution of microtubules, and cell length homeostasis, and predicts the effects of microtubule inhibitors on cell length. Together this experimental and theoretical analysis suggests that microtubule dynamics impose unexpected limits on cell geometry that enable cells to regulate their length. Since cells are the building blocks and architects of tissue morphogenesis, such intrinsically defined limits may be important for development and homeostasis in multicellular organisms.

  15. Determination of optimal gains for constrained controllers

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    Kwan, C.M.; Mestha, L.K.

    1993-08-01

    In this report, we consider the determination of optimal gains, with respect to a certain performance index, for state feedback controllers where some elements in the gain matrix are constrained to be zero. Two iterative schemes for systematically finding the constrained gain matrix are presented. An example is included to demonstrate the procedures.

  16. Homeostatic control of brain function – new approaches to understand epileptogenesis

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    Detlev eBoison

    2013-07-01

    Full Text Available Neuronal excitability of the brain and ongoing homeostasis depends not only on intrinsic neuronal properties but also on external environmental factors; together these determine the functionality of neuronal networks. Homeostatic factors become critically important during epileptogenesis, a process which involves complex disruption of self-regulatory mechanisms. Here we focus on the bioenergetic homeostatic network regulator adenosine, a purine nucleoside whose availability is regulated largely by astrocytes. Endogenous adenosine affects complex network function through adenosine receptor-mediated pathways, through mitochondrial bioenergetics, and through adenosine receptor-independent epigenetic functions. Accumulating evidence from our laboratories shows that disruption of adenosine homeostasis plays a major role in epileptogenesis. Conversely, we have found that reconstruction of adenosine’s homeostatic functions provides new hope for the prevention of epileptogenesis. We will discuss how adenosine-based therapeutic approaches may interfere with epileptogenesis on an epigenetic level, and how dietary interventions can be used to restore network homeostasis in the brain. We conclude that reconstruction of homeostatic functions in the brain offers a new conceptual advance for the treatment of neurological conditions that goes far beyond current target-centric treatment approaches.

  17. Selective insulin resistance in homeostatic and cognitive control brain areas in overweight and obese adults.

    Science.gov (United States)

    Kullmann, Stephanie; Heni, Martin; Veit, Ralf; Scheffler, Klaus; Machann, Jürgen; Häring, Hans-Ulrich; Fritsche, Andreas; Preissl, Hubert

    2015-06-01

    Impaired brain insulin action has been linked to obesity, type 2 diabetes, and neurodegenerative diseases. To date, the central nervous effects of insulin in obese humans still remain ill defined, and no study thus far has evaluated the specific brain areas affected by insulin resistance. In 25 healthy lean and 23 overweight/obese participants, we performed magnetic resonance imaging to measure cerebral blood flow (CBF) before and 15 and 30 min after application of intranasal insulin or placebo. Additionally, participants explicitly rated pictures of high-caloric savory and sweet food 60 min after the spray for wanting and liking. In response to insulin compared with placebo, we found a significant CBF decrease in the hypothalamus in both lean and overweight/obese participants. The magnitude of this response correlated with visceral adipose tissue independent of other fat compartments. Furthermore, we observed a differential response in the lean compared with the overweight/obese group in the prefrontal cortex, resulting in an insulin-induced CBF reduction in lean participants only. This prefrontal cortex response significantly correlated with peripheral insulin sensitivity and eating behavior measures such as disinhibition and food craving. Behaviorally, we were able to observe a significant reduction for the wanting of sweet foods after insulin application in lean men only. Brain insulin action was selectively impaired in the prefrontal cortex in overweight and obese adults and in the hypothalamus in participants with high visceral adipose tissue, potentially promoting an altered homeostatic set point and reduced inhibitory control contributing to overeating behavior. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  18. Gaining Control Over Fecal Incontinence.

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    Gump, Kendra; Schmelzer, Marilee

    2016-01-01

    Strategies that improve the regularity and efficiency of defecation can eliminate or minimize episodes of fecal incontinence. The medical-surgical nurse's role in identifying patients with fecal incontinence is discussed, along with various treatments to control bowel elimination.

  19. Gaining and sustaining schistosomiasis control

    DEFF Research Database (Denmark)

    Ezeamama, Amara E.; He, Chun-La; Shen, Ye;

    2016-01-01

    BACKGROUND: The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was established in 2008 to answer strategic questions about schistosomiasis control. For programme managers, a high-priority question is: what are the most cost-effective strategies for delivering preventiv...

  20. Gaining and sustaining schistosomiasis control

    DEFF Research Database (Denmark)

    Ezeamama, Amara E.; He, Chun-La; Shen, Ye

    2016-01-01

    BACKGROUND: The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was established in 2008 to answer strategic questions about schistosomiasis control. For programme managers, a high-priority question is: what are the most cost-effective strategies for delivering preventive...... chemotherapy (PCT) with praziquantel (PZQ)? This paper describes the process SCORE used to transform this question into a harmonized research protocol, the study design for answering this question, the village eligibility assessments and data resulting from the first year of the study. METHODS: Beginning......-aged children. Seven studies are currently being implemented in five African countries. During the first year, villages were screened for eligibility, and data were collected on prevalence and intensity of infection prior to randomisation and the implementation of different schemes of PZQ intervention...

  1. Gain control mechanisms in spinal motoneurons

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    Michael David Johnson

    2014-07-01

    Full Text Available Motoneurons provide the only conduit for motor commands to reach muscles. For many years, motoneurons were in fact considered to be little more than passive wires. Systematic studies in the past 25 years however have clearly demonstrated that the intrinsic electrical properties of motoneurons are under strong neuromodulatory control via multiple sources. The discovery of potent neuromodulation from the brainstem and its ability to change the gain of motoneurons shows that the passive view of the motor output stage is no longer tenable. A mechanism for gain control at the motor output stage makes good functional sense considering our capability of generating an enormous range of forces, from very delicate (e.g. putting in a contact lens to highly forceful (emergency reactions. Just as sensory systems need gain control to deal with a wide dynamic range of inputs, so to might motor output need gain control to deal with the wide dynamic range of the normal movement repertoire. Two problems emerge from the potential use of the brainstem monoaminergic projection to motoneurons for gain control. First, the projection is highly diffuse anatomically, so that independent control of the gains of different motor pools is not feasible. In fact, the system is so diffuse that gain for all the motor pools in a limb likely increases in concert. Second, if there is a system that increases gain, probably a system to reduce gain is also needed. In this review, we summarize recent studies that show local inhibitory circuits within the spinal cord, especially reciprocal and recurrent inhibition, have the potential to solve both of these problems as well as constitute another source of gain modulation.

  2. Photonic homeostatics

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    Liu, Timon C.; Li, Fan-Hui

    2010-11-01

    Photonic homeostatics is a discipline to study the establishment, maintenance, decay, upgrading and representation of function-specific homoestasis (FSH) by using photonics. FSH is a negative-feedback response of a biosystem to maintain the function-specific fluctuations inside the biosystem so that the function is perfectly performed. A stress may increase sirtuin 1 (SIRT1) activities above FSH-specific SIRT1 activity to induce a function far from its FSH. On the one hand, low level laser irradiation or monochromatic light (LLL) can not modulate a function in its FSH or a stress in its stress-specific homeostasis (StSH), but modulate a function far from its FSH or a stress far from its StSH. On the other hand, the biophotons from a biosystem with its function in its FSH should be less than the one from the biosystem with its function far from its FSH. The non-resonant interaction of low intensity laser irradiation or monochromatic light (LIL) and a kind of membrane protein can be amplified by all the membrane proteins if the function is far from its FSH. This amplification might hold for biophoton emission of the membrane protein so that the photonic spectroscopy can be used to represent the function far from its FSH, which is called photonomics.

  3. Two scale high gain adaptive control

    NARCIS (Netherlands)

    Polderman, Jan W.; Mareels, I.M.Y.; Mareels, Iven

    2004-01-01

    Simple adaptive controllers based on high gain output feedback suffer a lack of robustness with respect to bounded disturbances. Existing modifications achieve boundedness of all solutions but introduce solutions that, even in the absence of disturbances, do not achieve regulation. In this paper a

  4. Weight Gain Through Self-Control Procedures

    Science.gov (United States)

    Gulanick, Nancy; And Others

    1975-01-01

    Underweight subjects were assigned to either a self-reinforcement condition, a self-punishment condition, or to a discussion/reflection control condition. The subjects received one treatment session per week over a five-week period. After treatment, the self-reinforcement groups gained significantly more pounds (kilograms) than either of the other…

  5. Contrast Gain Control Model Fits Masking Data

    Science.gov (United States)

    Watson, Andrew B.; Solomon, Joshua A.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    We studied the fit of a contrast gain control model to data of Foley (JOSA 1994), consisting of thresholds for a Gabor patch masked by gratings of various orientations, or by compounds of two orientations. Our general model includes models of Foley and Teo & Heeger (IEEE 1994). Our specific model used a bank of Gabor filters with octave bandwidths at 8 orientations. Excitatory and inhibitory nonlinearities were power functions with exponents of 2.4 and 2. Inhibitory pooling was broad in orientation, but narrow in spatial frequency and space. Minkowski pooling used an exponent of 4. All of the data for observer KMF were well fit by the model. We have developed a contrast gain control model that fits masking data. Unlike Foley's, our model accepts images as inputs. Unlike Teo & Heeger's, our model did not require multiple channels for different dynamic ranges.

  6. Homeostatic theory of obesity

    Directory of Open Access Journals (Sweden)

    David F Marks

    2015-06-01

    Full Text Available Health is regulated by homeostasis, a property of all living things. Homeostasis maintains equilibrium at set-points using feedback loops for optimum functioning of the organism. Imbalances in homeostasis causing overweight and obesity are evident in more than 1 billion people. In a new theory, homeostatic obesity imbalance is attributed to a hypothesized ‘Circle of Discontent’, a system of feedback loops linking weight gain, body dissatisfaction, negative affect and over-consumption. The Circle of Discontent theory is consistent with an extensive evidence base. A four-armed strategy to halt the obesity epidemic consists of (1 putting a stop to victim-blaming, stigma and discrimination; (2 devalorizing the thin-ideal; (3 reducing consumption of energy-dense, low-nutrient foods and drinks; and (4 improving access to plant-based diets. If fully implemented, interventions designed to restore homeostasis have the potential to halt the obesity epidemic.

  7. Homeostatic theory of obesity.

    Science.gov (United States)

    Marks, David F

    2015-01-01

    Health is regulated by homeostasis, a property of all living things. Homeostasis maintains equilibrium at set-points using feedback loops for optimum functioning of the organism. Imbalances in homeostasis causing overweight and obesity are evident in more than 1 billion people. In a new theory, homeostatic obesity imbalance is attributed to a hypothesized 'Circle of Discontent', a system of feedback loops linking weight gain, body dissatisfaction, negative affect and over-consumption. The Circle of Discontent theory is consistent with an extensive evidence base. A four-armed strategy to halt the obesity epidemic consists of (1) putting a stop to victim-blaming, stigma and discrimination; (2) devalorizing the thin-ideal; (3) reducing consumption of energy-dense, low-nutrient foods and drinks; and (4) improving access to plant-based diets. If fully implemented, interventions designed to restore homeostasis have the potential to halt the obesity epidemic.

  8. DNA supercoiling in Escherichia coli is under tight and subtle homeostatic control, involving gene-expression and metabolic regulation of both topoisomerase I and DNA gyrase

    DEFF Research Database (Denmark)

    Snoep, J.L.; van der Weijden, C.C.; Andersen, H.W.;

    2002-01-01

    DNA of prokaryotes is in a nonequilibrium. structural state, characterized as 'active' DNA supercoiling. Alterations in this state affect many life processes and a homeostatic control of DNA supercoiling has been suggested [Menzel, R. & Gellert. M. (1983) Cell 34, 105-113]. We here report on a new...

  9. Gain control in the sonar of odontocetes.

    Science.gov (United States)

    Ya Supin, Alexander; Nachtigall, Paul E

    2013-06-01

    The sonar of odontocetes processes echo-signals within a wide range of echo levels. The level of echoes varies widely by tens of decibels depending on the level of the emitted sonar pulse, the target strength, the distance to the target, and the sound absorption by the water media. The auditory system of odontocetes must be capable of effective perception, analysis, and discrimination of echo-signals within all this variability. The sonar of odontocetes has several mechanisms to compensate for the echo-level variation (gain control). To date, several mechanisms of the biosonar gain control have been revealed in odontocetes: (1) adjustment of emitted sonar pulse levels (the longer the distance to the target, the higher the level of the emitted pulse), (2) short-term variation of hearing sensitivity based on forward masking of the echo by the preceding self-heard emitted pulse and subsequent release from the masking, and (3) active long-term control of hearing sensitivity. Recent investigations with the use of the auditory evoked-potential technique have demonstrated that these mechanisms effectively minimize the variation of the response to the echo when either the emitted sonar pulse level, or the target distance, or both vary within a wide range. A short review of these data is presented herein.

  10. Perception and Homeostatic Control of Iron in the Rhizobia and Related Bacteria.

    Science.gov (United States)

    O'Brian, Mark R

    2015-01-01

    Iron is an essential nutrient, but it can also be toxic. Therefore, iron homeostasis must be strictly regulated. Transcriptional control of iron-dependent gene expression in the rhizobia and other taxa of the Alphaproteobacteria is fundamentally different from the Fur paradigm in Escherichia coli and other model systems. Rather than sense iron directly, the rhizobia employ the iron response regulator (Irr) to monitor and respond to the status of an iron-dependent process, namely, heme biosynthesis. This novel control mechanism allows iron homeostasis to be integrated with other cellular processes, and it permits differential control of iron regulon genes in a manner not readily achieved by Fur. Moreover, studies of Irr have defined a role for heme in conditional protein stability that has been subsequently described in eukaryotes. Finally, Irr-mediated control of iron metabolism may reflect a cellular strategy that accommodates a greater reliance on manganese.

  11. IL-4 directly signals tissue-resident macrophages to proliferate beyond homeostatic levels controlled by CSF-1

    Science.gov (United States)

    Ruckerl, Dominik; Thomas, Graham D.; Hewitson, James P.; Duncan, Sheelagh; Brombacher, Frank; Maizels, Rick M.; Hume, David A.; Allen, Judith E.

    2013-01-01

    Macrophages (MΦs) colonize tissues during inflammation in two distinct ways: recruitment of monocyte precursors and proliferation of resident cells. We recently revealed a major role for IL-4 in the proliferative expansion of resident MΦs during a Th2-biased tissue nematode infection. We now show that proliferation of MΦs during intestinal as well as tissue nematode infection is restricted to sites of IL-4 production and requires MΦ-intrinsic IL-4R signaling. However, both IL-4Rα–dependent and –independent mechanisms contributed to MΦ proliferation during nematode infections. IL-4R–independent proliferation was controlled by a rise in local CSF-1 levels, but IL-4Rα expression conferred a competitive advantage with higher and more sustained proliferation and increased accumulation of IL-4Rα+ compared with IL-4Rα− cells. Mechanistically, this occurred by conversion of IL-4Rα+ MΦs from a CSF-1–dependent to –independent program of proliferation. Thus, IL-4 increases the relative density of tissue MΦs by overcoming the constraints mediated by the availability of CSF-1. Finally, although both elevated CSF1R and IL-4Rα signaling triggered proliferation above homeostatic levels, only CSF-1 led to the recruitment of monocytes and neutrophils. Thus, the IL-4 pathway of proliferation may have developed as an alternative to CSF-1 to increase resident MΦ numbers without coincident monocyte recruitment. PMID:24101381

  12. Hedonic and homeostatic overlap following fat ingestion

    OpenAIRE

    Begg, Denovan P.; Woods, Stephen C.

    2013-01-01

    Ingestion of fatty foods increases dopamine release in the substantianigra producing a positive hedonic state. Tellez et al. (2013) demonstrate that an intestinal signal generated by fat consumption, oleoylethanolamide, stimulates central dopamine activity, thus regulating the reward value of fat and establishing a link between caloric-homeostatic and hedonic-homeostatic controllers.

  13. Controlling noise in plasmonic structures with gain

    Science.gov (United States)

    Vyshnevyy, A. A.; Fedyanin, D. Yu.

    2017-09-01

    Loss compensation by gain medium gives the possibility to exploit subwavelength confinement of light in plasmonic nanostructures and construct nanoscale plasmonic circuits. However, due to fundamentally unavoidable spontaneous emission from the gain medium, lossless waveguides suffer from strong photonic noise, which limits their practical applications. Here we demonstrate the possibility of significant decrease of the noise level while preserving physical dimensions of lossless plasmonic waveguides with gain. Our findings are aimed at extending the communication capabilities of on-chip plasmonic networks.

  14. Stabilizing Gain Selection of Networked Variable Gain Controller to Maximize Robustness Using Particle Swarm Optimization

    CERN Document Server

    Pan, Indranil; Ghosh, Soumyajit; Gupta, Amitava; 10.1109/PACC.2011.5978958

    2012-01-01

    Networked Control Systems (NCSs) are often associated with problems like random data losses which might lead to system instability. This paper proposes a method based on the use of variable controller gains to achieve maximum parametric robustness of the plant controlled over a network. Stability using variable controller gains under data loss conditions is analyzed using a suitable Linear Matrix Inequality (LMI) formulation. Also, a Particle Swarm Optimization (PSO) based technique is used to maximize parametric robustness of the plant.

  15. Bumpless Transfer between Observer-based Gain Scheduled Controllers

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Stoustrup, Jakob; Trangbæk, Klaus

    2005-01-01

    This paper deals with bumpless transfer between a number of observer-based controllers in a gain scheduling architecture. Linear observer-based controllers are designed for a number of linear approximations of a nonlinear system in a set of operating points, and gain scheduling control can...

  16. Aircraft nonlinear optimal control using fuzzy gain scheduling

    Science.gov (United States)

    Nusyirwan, I. F.; Kung, Z. Y.

    2016-10-01

    Fuzzy gain scheduling is a common solution for nonlinear flight control. The highly nonlinear region of flight dynamics is determined throughout the examination of eigenvalues and the irregular pattern of root locus plots that show the nonlinear characteristic. By using the optimal control for command tracking, the pitch rate stability augmented system is constructed and the longitudinal flight control system is established. The outputs of optimal control for 21 linear systems are fed into the fuzzy gain scheduler. This research explores the capability in using both optimal control and fuzzy gain scheduling to improve the efficiency in finding the optimal control gains and to achieve Level 1 flying qualities. The numerical simulation work is carried out to determine the effectiveness and performance of the entire flight control system. The simulation results show that the fuzzy gain scheduling technique is able to perform in real time to find near optimal control law in various flying conditions.

  17. A Unified Approach to High-Gain Adaptive Controllers

    Directory of Open Access Journals (Sweden)

    Ian A. Gravagne

    2009-01-01

    Full Text Available It has been known for some time that proportional output feedback will stabilize MIMO, minimum-phase, linear time-invariant systems if the feedback gain is sufficiently large. High-gain adaptive controllers achieve stability by automatically driving up the feedback gain monotonically. More recently, it was demonstrated that sample-and-hold implementations of the high-gain adaptive controller also require adaptation of the sampling rate. In this paper, we use recent advances in the mathematical field of dynamic equations on time scales to unify and generalize the discrete and continuous versions of the high-gain adaptive controller. We prove the stability of high-gain adaptive controllers on a wide class of time scales.

  18. A novel control method for on-off gain and gain tilt of fiber Raman amplifiers

    Institute of Scientific and Technical Information of China (English)

    Xue Feng(冯雪); Wei Zhang(张巍); Xiaoming Liu(刘小明); Jiangde Peng(彭江得)

    2004-01-01

    Considering spectrum tilt due to signal-to-signal Raman scattering (SSRS) in backward distributed fiber Raman amplifiers (B-DFRA), an inverse tilted on-off gain profile is adopted to achieve flat net gain. A simple approximate linear relationship of pump power at each wavelength versus on-off gain level and tilt was derived numerically and experimentally so that a novel control method was established. Since there are only 3 pre-determinable constants required for individual pump wave, it is easy to be realized. As an example, maximum errors less than 0.2 and 0.4 dB respectively for average gain and gain tilt were achieved over C+L band in 100-km back-pumped standard single-mode fiber (SMF) experimentally.

  19. Adaptive Human Control Gains During Precision Grip

    Directory of Open Access Journals (Sweden)

    Erik D. Engeberg

    2013-03-01

    Full Text Available Eight human test subjects attempted to track a desired position trajectory with an instrumented manipulandum (MN. The test subjects used the MN with three different levels of stiffness. A transfer function was developed to represent the human application of a precision grip from the data when the test subjects initially displaced the MN so as to learn the position mapping from the MN onto the display. Another transfer function was formed from the data of the remainder of the experiments, after significant displacement of the MN occurred. Both of these transfer functions accurately modelled the system dynamics for a portion of the experiments, but neither was accurate for the duration of the experiments because the human grip dynamics changed while learning the position mapping. Thus, an adaptive system model was developed to describe the learning process of the human test subjects as they displaced the MN in order to gain knowledge of the position mapping. The adaptive system model was subsequently validated following comparison with the human test subject data. An examination of the average absolute error between the position predicted by the adaptive model and the actual experimental data yielded an overall average error of 0.34mm for all three levels of stiffness.

  20. L2-gain and passivity techniques in nonlinear control

    CERN Document Server

    van der Schaft, Arjan

    2017-01-01

    This standard text gives a unified treatment of passivity and L2-gain theory for nonlinear state space systems, preceded by a compact treatment of classical passivity and small-gain theorems for nonlinear input-output maps. The synthesis between passivity and L2-gain theory is provided by the theory of dissipative systems. Specifically, the small-gain and passivity theorems and their implications for nonlinear stability and stabilization are discussed from this standpoint. The connection between L2-gain and passivity via scattering is detailed. Feedback equivalence to a passive system and resulting stabilization strategies are discussed. The passivity concepts are enriched by a generalised Hamiltonian formalism, emphasising the close relations with physical modeling and control by interconnection, and leading to novel control methodologies going beyond passivity. The potential of L2-gain techniques in nonlinear control, including a theory of all-pass factorizations of nonlinear systems, and of parametrization...

  1. Help Your Child Gain Control Over Asthma

    Science.gov (United States)

    ... a pet inside, keep it out of your child’s bedroom. • Keep pets off of your furniture. • Vacuum carpets and furniture when your child is not around. Vacuum every week to help control pet hair and dust. 23 Cockroaches (“roaches” or other “ ...

  2. Gain scheduled control of linear systems with unsymmetrical saturation actuators

    Science.gov (United States)

    Wu, Wen-Juan; Duan, Guang-Ren

    2016-11-01

    The problem of stabilisation of a class of nonlinear continuous-time systems with asymmetric saturations on the control is studied in this paper. By combining the parametric Lyapunov equation approach and gain scheduling technique, a state feedback gain scheduling controller is proposed to solve the stabilisation problem of systems with unsymmetrical saturated control. The proposed gain scheduled approach is to increase the value of the design parameter so that the convergence rate of the closed-loop system can be increased. Numerical simulations show the effectiveness of the proposed approach.

  3. Neural responses to macronutrients: hedonic and homeostatic mechanisms.

    Science.gov (United States)

    Tulloch, Alastair J; Murray, Susan; Vaicekonyte, Regina; Avena, Nicole M

    2015-05-01

    The brain responds to macronutrients via intricate mechanisms. We review how the brain's neural systems implicated in homeostatic control of feeding and hedonic responses are influenced by the ingestion of specific types of food. We discuss how these neural systems are dysregulated in preclinical models of obesity. Findings from these studies can increase our understanding of overeating and, perhaps in some cases, the development of obesity. In addition, a greater understanding of the neural circuits affected by the consumption of specific macronutrients, and by obesity, might lead to new treatments and strategies for preventing unhealthy weight gain. Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.

  4. An output amplitude configurable wideband automatic gain control with high gain step accuracy

    Institute of Scientific and Technical Information of China (English)

    何晓丰; 莫太山; 马成炎; 叶甜春

    2012-01-01

    An output amplitude configurable wideband automatic gain control (AGC) with high gain step accuracy for the GNSS receiver is presented.The amplitude of an AGC is configurable in order to cooperate with baseband chips to achieve interference suppression and be compatible with different full range ADCs.And what's more,the gain-boosting technology is introduced and the circuit is improved to increase the step accuracy.A zero,which is composed by the source feedback resistance and the source capacity,is introduced to compensate for the pole.The AGC is fabricated in a 0.18 μm CMOS process.The AGC shows a 62 dB gain control range by 1 dB each step with a gain error of less than 0.2 dB.The AGC provides 3 dB bandwidth larger than 80 MHz and the overall power consumption is less than 1.8 mA,and the die area is 800 × 300μm2.

  5. Gain Scheduling for the Orion Launch Abort Vehicle Controller

    Science.gov (United States)

    McNamara, Sara J.; Restrepo, Carolina I.; Madsen, Jennifer M.; Medina, Edgar A.; Proud, Ryan W.; Whitley, Ryan J.

    2011-01-01

    One of NASAs challenges for the Orion vehicle is the control system design for the Launch Abort Vehicle (LAV), which is required to abort safely at any time during the atmospheric ascent portion of ight. The focus of this paper is the gain design and scheduling process for a controller that covers the wide range of vehicle configurations and flight conditions experienced during the full envelope of potential abort trajectories from the pad to exo-atmospheric flight. Several factors are taken into account in the automation process for tuning the gains including the abort effectors, the environmental changes and the autopilot modes. Gain scheduling is accomplished using a linear quadratic regulator (LQR) approach for the decoupled, simplified linear model throughout the operational envelope in time, altitude and Mach number. The derived gains are then implemented into the full linear model for controller requirement validation. Finally, the gains are tested and evaluated in a non-linear simulation using the vehicles ight software to ensure performance requirements are met. An overview of the LAV controller design and a description of the linear plant models are presented. Examples of the most significant challenges with the automation of the gain tuning process are then discussed. In conclusion, the paper will consider the lessons learned through out the process, especially in regards to automation, and examine the usefulness of the gain scheduling tool and process developed as applicable to non-Orion vehicles.

  6. Effects of oral contraceptives on selected parameters of the homeostatic control system in young women having a sudden disorder of the auditory and/or balance system.

    Science.gov (United States)

    Urbaniak, Joanna; Zielińska-Bliźniewska, Hanna; Miłoński, Jarosław; Pietkiewicz, Piotr; Kuśmierczyk, Krzysztof; Olszewski, Jurek

    2015-02-01

    The purpose of the paper was to assess the effects of oral contraceptives on selected parameters of the homeostatic control system in women having a sudden disorder of the auditory and/or balance system. The study included 105 young women divided into two groups: Group I--52 women with the disorder of the auditory and/or balance system using hormonal contraceptives for at least 2 months, aged 20-49; and Group II--53 women without any disorder of the auditory and/or balance system using hormonal contraceptives for at least 2 months, aged 18-40. The patients included in the study underwent a full otoneurological evaluation, detailed laryngological diagnostics and an evaluation of selected parameters of the homeostatic control system--fibrinogen level, D-dimer level, evaluation of APTT and PT indicator, plasma estradiol and progesterone with the Roche Cobas analyser by means of chemiluminescence. The vertigo occurring in the study group was most often central (59.6% of cases), mixed with compensation in 36.6% of cases, and peripheral only in 3.8% of cases, indicating labyrinth damage in 40.4% of cases. An analysis of the progesterone level, considering the menstrual cycle phase in the group, showed that its value was abnormal in 51.0% of women in the study group and 47.1% in the control group. In their own studies, the authors observed that the estradiol level in the plasma, considering the menstrual cycle phase in the study group, was abnormal in 41.2% of women and that the differences in its concentration were statistically significant in the study and control groups (p = 0.005), which may have a negative impact on the possibility of a thromboembolic episode.

  7. Gain Scheduling Control based on Closed-Loop System Identification

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Trangbæk, Klaus

    This paper deals with system identification and gain scheduling control of multi-variable nonlinear systems. We propose a novel scheme where a linear approximation of the system model is obtained in an operating point; then, a Youla-Kucera (YJBK) parameter specifying the difference between...... the first and a second operating point is identified in closed-loop using system identification methods with open-loop properties. Next, a linear controller is designed for this linearised model, and gain scheduling control can subsequently be achieved by interpolating between each controller...

  8. Humanoid Walking Robot: Modeling, Inverse Dynamics, and Gain Scheduling Control

    OpenAIRE

    Elvedin Kljuno; Williams, Robert L.

    2010-01-01

    This article presents reference-model-based control design for a 10 degree-of-freedom bipedal walking robot, using nonlinear gain scheduling. The main goal is to show concentrated mass models can be used for prediction of the required joint torques for a bipedal walking robot. Relatively complicated architecture, high DOF, and balancing requirements make the control task of these robots difficult. Although linear control techniques can be used to control bipedal robots, nonlinear control is n...

  9. Robust Optimal Adaptive Control Method with Large Adaptive Gain

    Science.gov (United States)

    Nguyen, Nhan T.

    2009-01-01

    In the presence of large uncertainties, a control system needs to be able to adapt rapidly to regain performance. Fast adaptation is referred to the implementation of adaptive control with a large adaptive gain to reduce the tracking error rapidly. However, a large adaptive gain can lead to high-frequency oscillations which can adversely affect robustness of an adaptive control law. A new adaptive control modification is presented that can achieve robust adaptation with a large adaptive gain without incurring high-frequency oscillations as with the standard model-reference adaptive control. The modification is based on the minimization of the Y2 norm of the tracking error, which is formulated as an optimal control problem. The optimality condition is used to derive the modification using the gradient method. The optimal control modification results in a stable adaptation and allows a large adaptive gain to be used for better tracking while providing sufficient stability robustness. Simulations were conducted for a damaged generic transport aircraft with both standard adaptive control and the adaptive optimal control modification technique. The results demonstrate the effectiveness of the proposed modification in tracking a reference model while maintaining a sufficient time delay margin.

  10. Remote Robot Control With High Force-Feedback Gain

    Science.gov (United States)

    Kim, Won S.

    1993-01-01

    Improved scheme for force-reflecting hand control of remote robotic manipulator provides unprecedently high force-reflection gain, even when dissimilar master and slave arms used. Three feedback loops contained in remote robot control system exerting position-error-based force feedback and compliance control. Outputs of force and torque sensors on robot not used directly for force reflection, but for compliance control, while errors in position used to generate reflected forces.

  11. Application of gain scheduling to the control of batch bioreactors

    Science.gov (United States)

    Cardello, Ralph; San, Ka-Yiu

    1987-01-01

    The implementation of control algorithms to batch bioreactors is often complicated by the inherent variations in process dynamics during the course of fermentation. Such a wide operating range may render the performance of fixed gain PID controllers unsatisfactory. In this work, a detailed study on the control of batch fermentation is performed. Furthermore, a simple batch controller design is proposed which incorporates the concept of gain-scheduling, a subclass of adaptive control, with oxygen uptake rate as an auxiliary variable. The control of oxygen tension in the biorector is used as a vehicle to convey the proposed idea, analysis and results. Simulation experiments indicate significant improvement in controller performance can be achieved by the proposed approach even in the presence of measurement noise.

  12. Control of Spacecraft Formation with Disturbance Rejection and Exponential Gains

    Directory of Open Access Journals (Sweden)

    R. Schlanbusch

    2013-01-01

    Full Text Available We address the problem of state feedback translational motion control of a spacecraft formation through a modified sliding surface controller using variable gains and I^2 action for disturbance rejection. The exponential varying gains ensure faster convergence of the state trajectories during attitude maneuver while keeping the gains small (and the system less stiff for station keeping. Integral action is introduced for rejection of disturbances with a constant nonzero mean such as aerodynamic drag. A direct consequence is a drop in energy consumption when affected by sensor noise and a decrease in size of the error states residual when operating close to the equilibrium point. A large number of simulation results are presented to show the control performance.

  13. Gain-assisted control of the Goos-Haenchen shift

    Energy Technology Data Exchange (ETDEWEB)

    Ziauddin,; Qamar, Sajid [Centre for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)

    2011-11-15

    A gain-assisted model is considered to study the Goos-Haenchen (GH) shift behavior in the reflected and transmitted light. In this model, a probe light is incident on a cavity containing three-level dilute gaseous atomic medium. The atom-field interaction follows two-photon Raman transitions, and the dielectric susceptibility of the medium exhibits dispersion and gain properties [L. J. Wang, A. Kuzmich, and A. Dogariu, Nature (London) 406, 227 (2000)]. Under appropriate conditions, two gain peaks are observed with anomalous dispersion between the peaks, whereas normal dispersion can be observed at and around the gain maxima. The manipulation of the detuning associated with the probe light field which interacts with the intracavity medium during its propagation through the cavity can lead to a control over negative and positive GH shift in the reflected and transmitted light beam via the anomalous and normal dispersion of the medium.

  14. Cognitive adaptation of sonar gain control in the bottlenose dolphin.

    Science.gov (United States)

    Kloepper, Laura N; Smith, Adam B; Nachtigall, Paul E; Buck, John R; Simmons, James A; Pacini, Aude F

    2014-01-01

    Echolocating animals adjust the transmit intensity and receive sensitivity of their sonar in order to regulate the sensation level of their echoes; this process is often termed automatic gain control. Gain control is considered not to be under the animal's cognitive control, but previous investigations studied animals ensonifying targets or hydrophone arrays at predictable distances. To test whether animals maintain gain control at a fixed level in uncertain conditions, we measured changes in signal intensity for a bottlenose dolphin (Tursiops truncatus) detecting a target at three target distances (2.5, 4 and 7 m) in two types of sessions: predictable and unpredictable. Predictable sessions presented the target at a constant distance; unpredictable sessions moved the target randomly between the three target positions. In the predictable sessions the dolphin demonstrated intensity distance compensation, increasing the emitted click intensity as the target distance increased. Additionally, as trials within sessions progressed, the animal adjusted its click intensity even from the first click in a click train, which is consistent with the animal expecting a target at a certain range. In the unpredictable sessions there was no significant difference of intensity with target distance until after the 7th click in a click train. Together, these results demonstrate that the bottlenose dolphin uses learning and expectation for sonar gain control.

  15. Observer-based H-infinity output feedback control with feedback gain and observer gain variations for Delta operator system

    Institute of Scientific and Technical Information of China (English)

    Ruiquan LIN; Fuwen YANG; Renchong PENG

    2009-01-01

    Considering that the controller feedback gain and the observer gain are of additive norm-bounded variations, a design method of observer-based H-infinity output feedback controller for uncertain Delta operator systems is proposed in this paper. A sufficient condition of such controllers is presented in linear matrix inequality (LMI) forms. A numerical example is then given to illustrate the effectiveness of this method, that is, the obtained controller guarantees the closed-loop system asymptotically stable and the expected H-infinity performance even if the controller feedback gain and the observer gain are varied.

  16. A gain-control theory of binocular combination.

    Science.gov (United States)

    Ding, Jian; Sperling, George

    2006-01-24

    In binocular combination, light images on the two retinas are combined to form a single "cyclopean" perceptual image, in contrast to binocular rivalry which occurs when the two eyes have incompatible ("rivalrous") inputs and only one eye;s stimulus is perceived. We propose a computational theory for binocular combination with two basic principles of interaction: in every spatial neighborhood, each eye (i) exerts gain control on the other eye's signal in proportion to the contrast energy of its own input and (ii) additionally exerts gain control on the other eye's gain control. For stimuli of ordinary contrast, when either eye is stimulated alone, the predicted cyclopean image is the same as when both eyes are stimulated equally, coinciding with an easily observed property of natural vision. The gain-control theory is contrast dependent: Very low-contrast stimuli to the left- and right-eye add linearly to form the predicted cyclopean image. The intrinsic nonlinearity manifests itself only as contrast increases. To test the theory more precisely, a horizontal sine wave grating of 0.68 cycles per degree is presented to each eye. The gratings differ in contrast and phase. The predicted (and perceived) cyclopean grating also is a sine wave; its apparent phase indicates the relative contribution of the two eyes to the cyclopean image. For 48 measured combinations of phase and contrast, the theory with only one estimated parameter accounts for 95% of the variance of the data. Therefore, a simple, robust, physiologically plausible gain-control theory accurately describes an early stage of binocular combination.

  17. Gain Scheduling of PID Controller Based on Fuzzy Systems

    Directory of Open Access Journals (Sweden)

    Singh Sandeep

    2016-01-01

    Full Text Available This paper aims to utilize fuzzy rules and reasoning to determine the controller parameters and the PID controller generates the control signal. The objective of this study is to simulate the proposed scheme on various processes and arrive at results providing better response of the system when compared with best industrial auto-tuning technique: Ziegler-Nichols. The proposed scheme is based upon the Ultimate Gain (Ku and the Period (Tu of the system. The error and rate of change in error gains are tuned manually to get the desired response using LabVIEW. This can also be done with various optimization techniques. A thumb rule for choosing the ranges for Kc, Kd and Ki has been obtained experimentally.

  18. Neural Network Based PID Gain Tuning of Chemical Plant Controller

    Science.gov (United States)

    Abe, Yoshihiro; Konishi, Masami; Imai, Jun; Hasegawa, Ryusaku; Watanabe, Masamori; Kamijo, Hiroaki

    In these years, plant control systems are highly automated and applied to many industries. The control performances change with the passage of time, because of the deterioration of plant facilities. This is why human experts tune the control system to improve the total plant performances. In this study, PID control system for the oil refining chemical plant process is treated. In oil refining, there are thousands of the control loops in the plant to keep the product quality at the desired value and to secure the safety of the plant operation. According to the ambiguity of the interference between control loops, it is difficult to estimate the plant dynamical model accurately. Using neuro emulator and recurrent neural networks model (RNN model) for emulation and tuning parameters, PID gain tuning system of chemical plant controller is constructed. Through numerical experiments using actual plant data, effect of the proposed method was ascertained.

  19. Fitts' law with an isometric controller: effects of order of control and control-display gain.

    Science.gov (United States)

    Kantowitz, B H; Elvers, G C

    1988-03-01

    Twenty-four male subjects performed a discrete positioning task using an isometric controller. Two levels of order of control (position and velocity) were factorially crossed with two levels of control-display gain. Fitts' law functions were found for each of the four conditions. The velocity control conditions had significantly steeper slopes than the corresponding position control conditions, but there was no main effect for gain. A predicted interaction between control-display gain and order of control was found, indicating that the relative benefit of high gain is greater for velocity control than for position control. The reaction time (RT) regression lines had steeper negative slopes than those attained by Jagacinski, Repperger, Moran, Ward, and Glass (1980), who used an isotonic controller. This is in agreement with the results of Falkenberg and Newell (1980), who found that as average velocity increases, RT decreases. The components of Fitts' law were investigated, and this showed that the RT finding was due to the amplitude of the target, which covaried with average velocity, but was not due to the width.

  20. Humanoid Walking Robot: Modeling, Inverse Dynamics, and Gain Scheduling Control

    Directory of Open Access Journals (Sweden)

    Elvedin Kljuno

    2010-01-01

    Full Text Available This article presents reference-model-based control design for a 10 degree-of-freedom bipedal walking robot, using nonlinear gain scheduling. The main goal is to show concentrated mass models can be used for prediction of the required joint torques for a bipedal walking robot. Relatively complicated architecture, high DOF, and balancing requirements make the control task of these robots difficult. Although linear control techniques can be used to control bipedal robots, nonlinear control is necessary for better performance. The emphasis of this work is to show that the reference model can be a bipedal walking model with concentrated mass at the center of gravity, which removes the problems related to design of a pseudo-inverse system. Another significance of this approach is the reduced calculation requirements due to the simplified procedure of nominal joint torques calculation. Kinematic and dynamic analysis is discussed including results for joint torques and ground force necessary to implement a prescribed walking motion. This analysis is accompanied by a comparison with experimental data. An inverse plant and a tracking error linearization-based controller design approach is described. We propose a novel combination of a nonlinear gain scheduling with a concentrated mass model for the MIMO bipedal robot system.

  1. Cutting edge: JAM-C controls homeostatic chemokine secretion in lymph node fibroblastic reticular cells expressing thrombomodulin.

    Science.gov (United States)

    Frontera, Vincent; Arcangeli, Marie-Laure; Zimmerli, Claudia; Bardin, Florence; Obrados, Elodie; Audebert, Stéphane; Bajenoff, Marc; Borg, Jean-Paul; Aurrand-Lions, Michel

    2011-07-15

    The development and maintenance of secondary lymphoid organs, such as lymph nodes, occur in a highly coordinated manner involving lymphoid chemokine production by stromal cells. Although developmental pathways inducing lymphoid chemokine production during organogenesis are known, signals maintaining cytokine production in adults are still elusive. In this study, we show that thrombomodulin and platelet-derived growth factor receptor α identify a population of fibroblastic reticular cells in which chemokine secretion is controlled by JAM-C. We demonstrate that Jam-C-deficient mice and mice treated with Ab against JAM-C present significant decreases in stromal cell-derived factor 1α (CXCL12), CCL21, and CCL19 intranodal content. This effect is correlated with reduced naive T cell egress from lymph nodes of anti-JAM-C-treated mice.

  2. The Role of Cholinergic Basal Forebrain Neurons in Adenosine-Mediated Homeostatic Control of Sleep: Lessons from 192 IgG-Saporin Lesions

    Science.gov (United States)

    Kalinchuk, Anna V.; McCarley, Robert W.; Stenberg, Dag; Porkka-Heiskanen, Tarja; Basheer, Radhika

    2013-01-01

    A topic of high current interest and controversy is the basis of the homeostatic sleep response, the increase in non-rapid-eye-movement (NREM) sleep and NREM-delta activity following sleep deprivation (SD). Adenosine, which accumulates in the cholinergic basal forebrain (BF) during SD, has been proposed as one of the important homeostatic sleep factors. It is suggested that sleep-inducing effects of adenosine are mediated by inhibiting the wake-active neurons of the BF, including cholinergic neurons. Here we examined the association between SD-induced adenosine release, the homeostatic sleep response and the survival of cholinergic neurons in the BF after injections of the immunotoxin 192 IgG-saporin (saporin) in rodents. We correlated SD-induced adenosine level in the BF and the homeostatic sleep response with the cholinergic cell loss 2 weeks after local saporin injections into the BF, as well as 2 and 3 weeks after intracerebroventricular (ICV) saporin injections. Two weeks after local saporin injection there was an 88% cholinergic cell loss, coupled with nearly complete abolition of the SD-induced adenosine increase in the BF, the homeostatic sleep response, and the sleep-inducing effects of BF adenosine infusion. Two weeks after ICV saporin injection there was a 59% cholinergic cell loss, correlated with significant increase in SD-induced adenosine level in the BF and an intact sleep response. Three weeks after ICV saporin injection there was an 87% cholinergic cell loss, nearly complete abolition of the SD-induced adenosine increase in the BF and the homeostatic response, implying that the time course of ICV saporin lesions is a key variable in interpreting experimental results. Taken together, these results strongly suggest that cholinergic neurons in the BF are important for the SD-induced increase in adenosine as well as for its sleep-inducing effects and play a major, although not exclusive, role in sleep homeostasis. PMID:18805464

  3. Gain Scheduling Control of an Islanded Microgrid Voltage

    Directory of Open Access Journals (Sweden)

    Haritza Camblong

    2014-07-01

    Full Text Available The aim of this research study has been to design a gain scheduling (GS digital controller in order to control the voltage of an islanded microgrid in the presence of fast varying loads (FVLs, and to compare it to a robust controller. The inverter which feeds the microgrid is connected to it through an inductance-capacitor-inductance (LCL filter. The oscillatory and nonlinear behaviour of the plant is analyzed in the whole operating zone. Afterwards, the design of the controllers which contain two loops in cascade are described. The first loop concerns the current control, while the second is linked to the voltage regulation. Two controllers, one defined as Robust and another one as GS controller, are designed for the two loops, emphasizing in their robustness and their ability to damp the oscillatory plant behaviour. To finish, some simulations are carried out to study and compare the two kinds of controllers in different operating points. The results show that both controllers damp the oscillatory behaviour of the plant in closed loop (CL, and that the GS controller ensures a better rejection of current disturbances from FVLs.

  4. Structured, Gain-Scheduled Control of Wind Turbines

    DEFF Research Database (Denmark)

    Adegas, Fabiano Daher

    2013-01-01

    Improvements in cost-effectiveness and reliability of wind turbines is a constant in the industry. This requires new knowledge and systematic methods for analyzing and designing the interaction of structural dynamics, aerodynamics, and controllers. This thesis presents novel methods and theoretical...... control developments, which contributes to the analysis and design of wind turbines in an integrated aeroservoelastic process. From a control point of view, a wind turbine is a challenging system since the wind, which is the energy source driving the machine, is a poorly known disturbance. Additionally......, wind turbines inherently exhibit time-varying nonlinear dynamics along their nominal operating trajectory, motivating the use of advanced control techniques such as gain-scheduling, to counteract performance degradation or even instability problems by continuously adapting to the dynamics of the plant...

  5. Robust, Gain-Scheduled Control of Wind Turbines

    DEFF Research Database (Denmark)

    Østergaard, Kasper Zinck

    Wind turbines are today large and efficient machines, which are combined into wind farms operating on par with conventional power plants. When looking back, this is significantly different from the status only a few years ago, when wind turbines were sold mainly to private people. This change...... in turbine owners has resulted in a new focus on operational reliability instead of turbine size. This research deals with investigating model-based gain-scheduling control of wind turbines by use of linear parameter varying (LPV) methods. The numerical challenges grow quickly with the model size...

  6. A high multivitamin diet fed to Wistar rat dams during pregnancy increases maternal weight gain later in life and alters homeostatic, hedonic and peripheral regulatory systems of energy balance.

    Science.gov (United States)

    Pannia, Emanuela; Cho, Clara E; Kubant, Ruslan; Sánchez-Hernández, Diana; Huot, Pedro S P; Chatterjee, Diptendu; Fleming, Alison; Anderson, G Harvey

    2015-02-01

    High multivitamin (10-fold, HV) and high folic acid (Fol) diets fed to pregnant Wistar rats increase body weight and characteristics of the metabolic syndrome in their offspring. Our objective was to determine the effects of a HV maternal diet on dams and whether methyl vitamins contribute to these effects. Pregnant Wistar rats were fed AIN-93G diets containing either (1) recommended multivitamins (RV, control), (2) HV, (3) HV with recommended Fol (HVRF; 1-fold Fol), or (4) RV with high methyl group vitamins (HMethyl; 10-fold Fol, vitamin B12 and B6). All groups were fed a RV diet during lactation until weaning and a RV high fat (HF; 60% fat) diet for 16 weeks post-weaning. The HV, HVRF and HMethyl diet fed dams gained 45% more weight from 2 to 15 weeks post-weaning and their weight gain (WG) was positively associated with cumulative post-weaning food intake (FI). However, only HV dams had a reduced preference for a sucrose solution, lower mesolimbic dopamine (DA) turnover in the nucleus accumbens (NAc), and higher expression of several genes involved in FI regulation in the arcuate nucleus of the hypothalamus (ARC). Energy conserving peroxisome proliferator-activated receptor (Ppar)-γ in adipose and -α in liver was also greater in these dams consistent with their WG. In conclusion, HV, HVRF and HMethyl maternal diets exacerbate maternal WG when dams are exposed to a HF diet post-weaning. However, the diets differed in their effects on central and peripheral regulatory systems of energy balance. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. LPV gain-scheduled control of SCR aftertreatment systems

    Science.gov (United States)

    Meisami-Azad, Mona; Mohammadpour, Javad; Grigoriadis, Karolos M.; Harold, Michael P.; Franchek, Matthew A.

    2012-01-01

    Hydrocarbons, carbon monoxide and some of other polluting emissions produced by diesel engines are usually lower than those produced by gasoline engines. While great strides have been made in the exhaust aftertreatment of vehicular pollutants, the elimination of nitrogen oxide (NO x ) from diesel vehicles is still a challenge. The primary reason is that diesel combustion is a fuel-lean process, and hence there is significant unreacted oxygen in the exhaust. Selective catalytic reduction (SCR) is a well-developed technology for power plants and has been recently employed for reducing NO x emissions from automotive sources and in particular, heavy-duty diesel engines. In this article, we develop a linear parameter-varying (LPV) feedforward/feedback control design method for the SCR aftertreatment system to decrease NO x emissions while keeping ammonia slippage to a desired low level downstream the catalyst. The performance of the closed-loop system obtained from the interconnection of the SCR system and the output feedback LPV control strategy is then compared with other control design methods including sliding mode, and observer-based static state-feedback parameter-varying control. To reduce the computational complexity involved in the control design process, the number of LPV parameters in the developed quasi-LPV (qLPV) model is reduced by applying the principal component analysis technique. An LPV feedback/feedforward controller is then designed for the qLPV model with reduced number of scheduling parameters. The designed full-order controller is further simplified to a first-order transfer function with a parameter-varying gain and pole. Finally, simulation results using both a low-order model and a high-fidelity and high-order model of SCR reactions in GT-POWER interfaced with MATLAB/SIMULINK illustrate the high NO x conversion efficiency of the closed-loop SCR system using the proposed parameter-varying control law.

  8. Divisive gain modulation of motoneurons by inhibition optimizes muscular control.

    Science.gov (United States)

    Vestergaard, Mikkel; Berg, Rune W

    2015-02-25

    When using muscles, the precision with which force is delivered is as important as the delivery of force itself. Force is regulated by both the number of recruited motoneurons and their spike frequency. While it is known that the recruitment is ordered to reduce variability in force, it remains unclear whether the motoneuron gain, i.e., the slope of the transformation between synaptic input and spiking output, is also modulated to reduce variability in force. To address this issue, we use turtle hindlimb scratching as a model for fine motor control, since this behavior involves precise limb movement to rub the location of somatic nuisance touch. We recorded intracellularly from motoneurons in a reduced preparation where the limbs were removed to increase mechanical stability and the motor nerve activity served as a surrogate for muscle force. We found that not only is the gain of motoneurons regulated on a subsecond timescale, it is also adjusted to minimize variability. The modulation is likely achieved via an expansive nonlinearity between spike rate and membrane potential with inhibition having a divisive influence. These findings reveal a versatile mechanism of modulating neuronal sensitivity and suggest that such modulation is fundamentally linked to optimization.

  9. Modeling of a Multiple Digital Automatic Gain Control System

    Institute of Scientific and Technical Information of China (English)

    WANG Jingdian; LU Xiuhong; ZHANG Li

    2008-01-01

    Automatic gain control (AGC) has been used in many applications. The key features of AGC, including a steady state output and static/dynamic timing response, depend mainly on key parameters such as the reference and the filter coefficients. A simple model developed to describe AGC systems based on several simple assumptions shows that AGC always converges to the reference and that the timing constant depends on the filter coefficients. Measures are given to prevent oscillations and limit cycle effects. The simple AGC system is adapted to a multiple AGC system for a TV tuner in a much more efficient model. Simulations using the C language are 16 times faster than those with MATLAB, and 10 times faster than those with a mixed register transfer level (RTL)-simulation program with integrated circuit emphasis (SPICE) model.

  10. Evaluation Performance of IC Engine: Linear Tunable Gain Computed Torque Controller vs. Sliding Mode Controller

    Directory of Open Access Journals (Sweden)

    Shahnaz Tayebi Haghighi

    2013-05-01

    Full Text Available Design a nonlinear controller for second order nonlinear uncertain dynamical systems (e.g., internal combustion engine is one of the most important challenging works. This paper focuses on the comparative study between two important nonlinear controllers namely; computed torque controller (CTC and sliding mode controller (SMC and applied to internal combustion (IC engine in presence of uncertainties. In order to provide high performance nonlinear methodology, sliding mode controller and computed torque controller are selected. Pure SMC and CTC can be used to control of partly known nonlinear dynamic parameters of IC engine. Pure sliding mode controller and computed torque controller have difficulty in handling unstructured model uncertainties. To solve this problem applied linear error-based tuning method to sliding mode controller and computed torque controller for adjusting the sliding surface gain (λ and linear inner loop gain (K. Since the sliding surface gain (λ and linear inner loop gain (K are adjusted by linear error-based tuning method. In this research new λ and new K are obtained by the previous λ and K multiple gains updating factor(α. The results demonstrate that the error-based linear SMC and CTC are model-based controllers which works well in certain and uncertain system. These controllers have acceptable performance in presence of uncertainty.

  11. Accurately control and flatten gain spectrum of L-band erbium doped fiber amplifier based on suitable gain-clamping

    Science.gov (United States)

    Yang, Jiuru; Meng, Xiangyu; Liu, Chunyu

    2016-04-01

    The increasing traffic with dynamic nature requires the applications of gain-clamped L-band erbium-doped fiber amplifier (EDFA). However, the weak or over clamping may lead the unexpected gain-compression and flatness-worsening. In this article, to enhance practicality, we modify the partly gain-clamping configuration and utilize a pair of C-band fiber Bragg gratings (FBGs) to non-uniformly compress the gain spectrum of L-band. Through a comprehensive test and comparison, the suitable gain-clamping region for the amplified signals is found, and the gain in L-band is accurately controlled and flattened under the matched central wavelength of FBGs. The experimental results show that, our designed L-band EDFA achieves a trade-off among the output gain, flatness and stability. The ±0.44 dB flatness and 20.2 dB average gain are together obtained in the range of 1570-1610 nm, with the ±0.1 dB stability of signals in over 30 dBm dynamic range.

  12. On controllability of neuronal networks with constraints on the average of control gains.

    Science.gov (United States)

    Tang, Yang; Wang, Zidong; Gao, Huijun; Qiao, Hong; Kurths, Jürgen

    2014-12-01

    Control gains play an important role in the control of a natural or a technical system since they reflect how much resource is required to optimize a certain control objective. This paper is concerned with the controllability of neuronal networks with constraints on the average value of the control gains injected in driver nodes, which are in accordance with engineering and biological backgrounds. In order to deal with the constraints on control gains, the controllability problem is transformed into a constrained optimization problem (COP). The introduction of the constraints on the control gains unavoidably leads to substantial difficulty in finding feasible as well as refining solutions. As such, a modified dynamic hybrid framework (MDyHF) is developed to solve this COP, based on an adaptive differential evolution and the concept of Pareto dominance. By comparing with statistical methods and several recently reported constrained optimization evolutionary algorithms (COEAs), we show that our proposed MDyHF is competitive and promising in studying the controllability of neuronal networks. Based on the MDyHF, we proceed to show the controlling regions under different levels of constraints. It is revealed that we should allocate the control gains economically when strong constraints are considered. In addition, it is found that as the constraints become more restrictive, the driver nodes are more likely to be selected from the nodes with a large degree. The results and methods presented in this paper will provide useful insights into developing new techniques to control a realistic complex network efficiently.

  13. Emerging Links between Homeostatic Synaptic Plasticity and Neurological Disease

    Directory of Open Access Journals (Sweden)

    Dion eDickman

    2013-11-01

    Full Text Available Homeostatic signaling systems are ubiquitous forms of biological regulation, having been studied for hundreds of years in the context of diverse physiological processes including body temperature and osmotic balance. However, only recently has this concept been brought to the study of excitatory and inhibitory electrical activity that the nervous system uses to establish and maintain stable communication. Synapses are a primary target of neuronal regulation with a variety of studies over the past 15 years demonstrating that these cellular junctions are under bidirectional homeostatic control. Recent work from an array of diverse systems and approaches has revealed exciting new links between homeostatic synaptic plasticity and a variety of seemingly disparate neurological and psychiatric diseases. These include autism spectrum disorders, intellectual disabilities, schizophrenia, and Fragile X Syndrome. Although the molecular mechanisms through which defective homeostatic signaling may lead to disease pathogenesis remain unclear, rapid progress is likely to be made in the coming years using a powerful combination of genetic, imaging, electrophysiological, and next generation sequencing approaches. Importantly, understanding homeostatic synaptic plasticity at a cellular and molecular level may lead to developments in new therapeutic innovations to treat these diseases. In this review we will examine recent studies that demonstrate homeostatic control of postsynaptic protein translation, retrograde signaling, and presynaptic function that may contribute to the etiology of complex neurological and psychiatric diseases.

  14. Emerging links between homeostatic synaptic plasticity and neurological disease.

    Science.gov (United States)

    Wondolowski, Joyce; Dickman, Dion

    2013-11-21

    Homeostatic signaling systems are ubiquitous forms of biological regulation, having been studied for hundreds of years in the context of diverse physiological processes including body temperature and osmotic balance. However, only recently has this concept been brought to the study of excitatory and inhibitory electrical activity that the nervous system uses to establish and maintain stable communication. Synapses are a primary target of neuronal regulation with a variety of studies over the past 15 years demonstrating that these cellular junctions are under bidirectional homeostatic control. Recent work from an array of diverse systems and approaches has revealed exciting new links between homeostatic synaptic plasticity and a variety of seemingly disparate neurological and psychiatric diseases. These include autism spectrum disorders, intellectual disabilities, schizophrenia, and Fragile X Syndrome. Although the molecular mechanisms through which defective homeostatic signaling may lead to disease pathogenesis remain unclear, rapid progress is likely to be made in the coming years using a powerful combination of genetic, imaging, electrophysiological, and next generation sequencing approaches. Importantly, understanding homeostatic synaptic plasticity at a cellular and molecular level may lead to developments in new therapeutic innovations to treat these diseases. In this review we will examine recent studies that demonstrate homeostatic control of postsynaptic protein translation, retrograde signaling, and presynaptic function that may contribute to the etiology of complex neurological and psychiatric diseases.

  15. Mechanisms of GABAergic Homeostatic Plasticity

    Directory of Open Access Journals (Sweden)

    Peter Wenner

    2011-01-01

    Full Text Available Homeostatic plasticity ensures that appropriate levels of activity are maintained through compensatory adjustments in synaptic strength and cellular excitability. For instance, excitatory glutamatergic synapses are strengthened following activity blockade and weakened following increases in spiking activity. This form of plasticity has been described in a wide array of networks at several different stages of development, but most work and reviews have focussed on the excitatory inputs of excitatory neurons. Here we review homeostatic plasticity of GABAergic neurons and their synaptic connections. We propose a simplistic model for homeostatic plasticity of GABAergic components of the circuitry (GABAergic synapses onto excitatory neurons, excitatory connections onto GABAergic neurons, cellular excitability of GABAergic neurons: following chronic activity blockade there is a weakening of GABAergic inhibition, and following chronic increases in network activity there is a strengthening of GABAergic inhibition. Previous work on GABAergic homeostatic plasticity supports certain aspects of the model, but it is clear that the model cannot fully account for some results which do not appear to fit any simplistic rule. We consider potential reasons for these discrepancies.

  16. POWER CONTROL AND ANTENNA GAIN OPTIMIZATION DURING WIMAX HANDOVER

    Directory of Open Access Journals (Sweden)

    P.P. Edwin Winston

    2012-04-01

    Full Text Available Wireless systems have recently been becoming faster and more intelligent. However the high speed access and intelligence make the power consumption of wireless systems high. In the WiMAX system, the MS transmission power is controlled in order to avoid exceeding the BS’s total receiving power from an antenna. Conventional wireless network design has long used base site sectorization and single, omni-directional antennas at the enduser device to serve the communications link, with advanced multi-antenna implementations operators have a new suite of tools to develop the robust wireless networks of the future. Revolutionary multiple antenna techniques at the base station and end-user device, paired with sophisticated signal processing and power consumption control, can dramatically improve the communications link for the most demanding applicationscenarios including heavily obstructed propagation environments and high speed mobility service. This paper presents results of an experimental study, simulation based, directed to determine the optimum transmission power and Antenna gain which influence on the overall handover performance in mobility scenarios, related toWiMAX communications. Based on them, optimal parameter sets can be provided by the network operator to mobile station, to guide its adaptation of the major WiMAX parameters to its speed and network topology and to help the handover decision.

  17. Flexible Joints Robotic Manipulator Control By Adaptive Gain Smooth Sliding Observer-Controller

    Directory of Open Access Journals (Sweden)

    A. FILIPESCU

    2003-12-01

    Full Text Available An adaptive gain sliding observer for uncertain parameter nonlinear systems together with an adaptive gain sliding controller is proposed in this paper. It considered nonlinear, SISO affine systems, with uncertainties in steady-state functions and parameters. A further parameter term, adaptively updated, has been introduced in steady state space model of the controlled system, in order to obtain useful information despite fault detection and isolation. By using of the sliding observer with adaptive gain, the robustness to uncertainties is increased and the parameters adaptively updated can provide useful information in fault detection. Also, the state estimation error is bounded accordingly with bound limits of the uncertainties. The both of them, the sliding adaptive observer and sliding controller are designed to fulfill the attractiveness condition of its corresponding switching surface. An application to a single arm with flexible joint robot is presented. In order to alleviate chattering, a parameterized tangent hyperbolic has been used as switching function, instead of pure relay one, to the observer and the controller. Also, the gains of the switching functions, to the sliding observer and sliding controller are adaptively updated depending of estimation error and tracking error, respectively. By the using adaptive gains, the transient and tracking response can be improved.

  18. Gain Scheduling Control of Gas Turbine Engines: Absolute Stability by Finding a Common Lyapunov Matrix

    OpenAIRE

    Pakmehr, Mehrdad; Fitzgerald, Nathan; Feron, Eric; Shamma, Jeff; Behbahani, Alireza

    2012-01-01

    This manuscript aims to develop and describe gain scheduling control concept for a gas turbine engine which drives a variable pitch propeller. An architecture for gain-scheduling control is developed that controls the turboshaft engine for large thrust commands in stable fashion with good performance. Fuel ow and propeller pitch angle are the two control inputs of the system. New stability proof has been developed for gain scheduling control of gas turbine engines using global linearization a...

  19. Gain-Scheduled Control of a Fossil-Fired Power Plant Boiler

    DEFF Research Database (Denmark)

    Hangstrup, M.; Stoustrup, Jakob; Andersen, Palle;

    1999-01-01

    In this paper the objective is to optimize the control of a coal fired 250 MW power plant boiler. The conventional control system is supplemented with a multivariable optimizing controller operating in parallel with the conventional control system. Due to the strong dependence of the gains...... and dynamics upon the load, it is beneficial to consider a gain-scheduling control approach. Optimization using complex mu synthesis results in unstable LTI controllers in some operating points of the boiler. A recent gain-scheduling approach allowing for unstable fixed LTI controllers is applied. Gain...

  20. Effects of phase on homeostatic spike rates.

    Science.gov (United States)

    Fisher, Nicholas; Talathi, Sachin S; Carney, Paul R; Ditto, William L

    2010-05-01

    Recent experimental results by Talathi et al. (Neurosci Lett 455:145-149, 2009) showed a divergence in the spike rates of two types of population spike events, representing the putative activity of the excitatory and inhibitory neurons in the CA1 area of an animal model for temporal lobe epilepsy. The divergence in the spike rate was accompanied by a shift in the phase of oscillations between these spike rates leading to a spontaneous epileptic seizure. In this study, we propose a model of homeostatic synaptic plasticity which assumes that the target spike rate of populations of excitatory and inhibitory neurons in the brain is a function of the phase difference between the excitatory and inhibitory spike rates. With this model of homeostatic synaptic plasticity, we are able to simulate the spike rate dynamics seen experimentally by Talathi et al. in a large network of interacting excitatory and inhibitory neurons using two different spiking neuron models. A drift analysis of the spike rates resulting from the homeostatic synaptic plasticity update rule allowed us to determine the type of synapse that may be primarily involved in the spike rate imbalance in the experimental observation by Talathi et al. We find excitatory neurons, particularly those in which the excitatory neuron is presynaptic, have the most influence in producing the diverging spike rates and causing the spike rates to be anti-phase. Our analysis suggests that the excitatory neuronal population, more specifically the excitatory to excitatory synaptic connections, could be implicated in a methodology designed to control epileptic seizures.

  1. Adaptive Control for Nonlinear Systems with Time-Varying Control Gain

    Directory of Open Access Journals (Sweden)

    Alejandro Rincon

    2012-01-01

    Full Text Available We propose a scheme for nonlinear plants with time-varying control gain and time-varying plant coefficients, on the basis of a plant model consisting of a Brunovsky-type model with polynomials as approximators. We develop an adaptive robust control scheme for this plant, under the following assumptions: (i the plant terms involve time-varying but bounded coefficients, being its upper bound unknown; (ii the control gain is unknown, not necessarily bounded, and only its signum is known. To achieve robustness, we use a combination of robustifying control inputs and dead zone-type update laws. We apply this methodology to the speed control of a permanent magnet synchronous motor (PMSM, and we achieve proper tracking results.

  2. Homeostasis balance, homeostasis imbalance or distinct motivational processes? Comments on Marks (2015) 'Homeostatic Theory of Obesity'.

    Science.gov (United States)

    Pelletier, Luc G; Guertin, Camille; Pope, J Paige; Rocchi, Meredith

    2016-01-01

    In his article, 'Homeostatic theory of obesity', Marks suggested that imbalances in homeostatic processes could explain weight gain and obesity. He proposes that over-consumption of high-caloric, low-nutrient and low satiating foods, combined with a stressful environment, is the origin of weight gain. Once weight gain occurs, individuals may develop body dissatisfaction and negative affect, leading to continued over-consumption, which sets in motion a system of feedback loops that leads to a Circle of Discontent and further weight gain. In this article, we attempt to clarify certain problematic aspects of Marks framework and identify specific directions that researchers should pursue to address these shortcomings.

  3. Control of microbial fuel cell voltage using a gain scheduling control strategy

    Science.gov (United States)

    Boghani, Hitesh C.; Michie, Iain; Dinsdale, Richard M.; Guwy, Alan J.; Premier, Giuliano C.

    2016-08-01

    Recent microbial fuel cell (MFC) research frequently addresses matters associated with scale and deployability. Modularisation is often needed to reduce ohmic losses with increasing volume. Series/parallel is then often an obvious strategy to enhance power quality during operation, to make best use of generated electricity. Hence, voltage reversal resulting from power and voltage mismatch between cells become virtually unavoidable. Control MFC voltages could be used to stabilise MFC stacks. Here, nonlinear MFCs are controlled using simple gain scheduled Proportional + Integral actions. Parsimonious control may be necessary for implementation in MFC arrays, so minimising costs. Controller parameterisation used several linearised models over the dynamic operating range of the MFCs. Controller gains were then scheduled according to the operating conditions. A digital potentiometer was used to actuate the control, varying the current sourced from the MFC. The results show that the controller was able to control MFC voltages, rejecting the disturbances. It was shown that the controller was transferable between MFCs with different power performances. This study demonstrates that the control of MFCs can be achieved with relatively simple digital approaches, plausibly implementable using low cost microcontrollers, and likely to be useful in the effective deployment of MFCs in large scale arrays.

  4. Multi-dimensional Gain Scheduling with Application to Power Plant Control

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Stoustrup, Jakob; Trangbæk, Klaus

    2003-01-01

    This paper deals with gain scheduling control of a power plant model, which is an example of a multi-dimensional nonlinear system. Linear observer-based controllers are designed for a number of linear approximations of the system model in a set of operating points, and gain-scheduling control can...

  5. Backstepping Designs for Aircraft Control - What is there to Gain?

    OpenAIRE

    Härkegård, Ola

    2001-01-01

    Aircraft flight control design is traditionally based on linear control theory, due to the existing wealth of tools for linear design and analysis. However, in order to achieve tactical advantages, modern fighter aircraft strive towards performing maneuvers outside the region where the dynamics of flight are linear, and the need for nonlinear tools arises. In this paper, backstepping is proposed as a possible framework for nonlinear flight control design. Its capabilities of handling five maj...

  6. Two stage dual gate MESFET monolithic gain control amplifier for Ka-band

    Science.gov (United States)

    Sokolov, V.; Geddes, J.; Contolatis, A.

    A monolithic two stage gain control amplifier has been developed using submicron gate length dual gate MESFETs fabricated on ion implanted material. The amplifier has a gain of 12 dB at 30 GHz with a gain control range of over 30 dB. This ion implanted monolithic IC is readily integrable with other phased array receiver functions such as low noise amplifiers and phase shifters.

  7. Homeostatic Immunity and the Microbiota.

    Science.gov (United States)

    Belkaid, Yasmine; Harrison, Oliver J

    2017-04-18

    The microbiota plays a fundamental role in the induction, education, and function of the host immune system. In return, the host immune system has evolved multiple means by which to maintain its symbiotic relationship with the microbiota. The maintenance of this dialogue allows the induction of protective responses to pathogens and the utilization of regulatory pathways involved in the sustained tolerance to innocuous antigens. The ability of microbes to set the immunological tone of tissues, both locally and systemically, requires tonic sensing of microbes and complex feedback loops between innate and adaptive components of the immune system. Here we review the dominant cellular mediators of these interactions and discuss emerging themes associated with our current understanding of the homeostatic immunological dialogue between the host and its microbiota. Published by Elsevier Inc.

  8. OPTIMAL-TUNING OF PID CONTROLLER GAINS USING GENETIC ALGORITHMS

    Directory of Open Access Journals (Sweden)

    Ömer GÜNDOĞDU

    2005-01-01

    Full Text Available This paper presents a method of optimum parameter tuning of a PID controller to be used in driving an inertial load by a dc motor thorough a gearbox. Specifically, the method uses genetic algorithms to determine the optimum controller parameters by minimizing the sum of the integral of the squared error and the squared controller output deviated from its steady state value. The paper suggests the use of Ziegler-Nichols settings to form the intervals for the controller parameters in which the population to be formed. The results obtained from the genetic algorithms are compared with the ones from Ziegler-Nichols in both figures and tabular form. Comparatively better results are obtained in the genetic algorithm case.

  9. Disruption of B-cell homeostatic control mediated by the BLV-Tax oncoprotein: association with the upregulation of Bcl-2 and signaling through NF-kappaB.

    Science.gov (United States)

    Szynal, Maud; Cleuter, Yvette; Beskorwayne, Terry; Bagnis, Claude; Van Lint, Carine; Kerkhofs, Pierre; Burny, Aisene; Martiat, Philippe; Griebel, Philip; Van den Broeke, Anne

    2003-07-17

    Transactivating proteins associated with complex onco-retroviruses including human T-cell leukemia virus-1 (HTLV-1) and bovine leukemia virus (BLV) mediate transformation using poorly understood mechanisms. To gain insight into the processes that govern tumor onset and progression, we have examined the impact of BLV-Tax expression on ovine B-cells, the targets of BLV in experimentally infected sheep, using B-cell clones that are dependent on CD154 and gammac-common cytokines. Tax was capable of mediating progression of B-cells from cytokine dependence to cytokine independence, indicating that the transactivator can over-ride signaling pathways typically controlled by cytokine receptor activation in B-cells. When examined in the presence of both CD154 and interleukin-4, Tax had a clear supportive role on B-cell growth, with an impact on B-cell proliferation, cell cycle phase distribution, and survival. Apoptotic B-cell death mediated by growth factor withdrawal, physical insult, and NF-kappaB inhibition was dramatically reduced in the presence of Tax. Furthermore, the expression of Tax was associated with higher Bcl-2 protein levels, providing rationale for the rescue signals mediated by the transactivator. Finally, Tax expression in B-cells led to a dramatic increase of nuclear RelB/p50 and p50/p50 NF-kappaB dimers, indicating that cellular signaling through NF-kappaB is a major contributory mechanism in the disruption of B-cell homeostasis. Although Tax is involved in aspects of pathogenesis that are unique to complex retroviruses, the viral strategies associated with this transactivating oncoprotein may have wide-ranging effects that are relevant to other B-cell malignancies.

  10. Development of an Automatic Gain Controller Card or Next Generation EDFAs

    Institute of Scientific and Technical Information of China (English)

    C. Y. Liaw; T. H. Cheng; C. Lu; M.Akiyama; T.Sakai; A.Wada

    2003-01-01

    This paper describes a low cost automatic gain controller card that provides fast transient gain control to maintain the power of the surviving channels when the number of input channels to an erbium-doped fiber amplifier (EDFA)changes rapidly.

  11. Moving HAIRS: Towards adaptive, homeostatic materials

    Science.gov (United States)

    Aizenberg, Joanna

    Dynamic structures that respond reversibly to changes in their environment are central to self-regulating thermal and lighting systems, targeted drug delivery, sensors, and self-propelled locomotion. Since an adaptive change requires energy input, an ideal strategy would be to design materials that harvest energy directly from the environment and use it to drive an appropriate response. This lecture will present the design of a novel class of reconfigurable materials that use surfaces bearing arrays of nanostructures put in motion by environment-responsive gels. Their unique hybrid architecture, and chemical and mechanical properties can be optimized to confer a wide range of adaptive behaviors. Using both experimental and modeling approaches, we are developing these hydrogel-actuated integrated responsive systems (HAIRS) as new materials with reversible optical and wetting properties, as a multifunctional platform for controlling cell differentiation and function, and as a first homeostatic system with autonomous self-regulation.

  12. Vector Control Algorithm for Electric Vehicle AC Induction Motor Based on Improved Variable Gain PID Controller

    Directory of Open Access Journals (Sweden)

    Gang Qin

    2015-01-01

    Full Text Available The acceleration performance of EV, which affects a lot of performances of EV such as start-up, overtaking, driving safety, and ride comfort, has become increasingly popular in recent researches. An improved variable gain PID control algorithm to improve the acceleration performance is proposed in this paper. The results of simulation with Matlab/Simulink demonstrate the effectiveness of the proposed algorithm through the control performance of motor velocity, motor torque, and three-phase current of motor. Moreover, it is investigated that the proposed controller is valid by comparison with the other PID controllers. Furthermore, the AC induction motor experiment set is constructed to verify the effect of proposed controller.

  13. Bidders' gains and family control of private target firms

    NARCIS (Netherlands)

    Gonenc, Halit; Hermes, Niels; van Sinderen, Erik

    2013-01-01

    This paper examines the announcement returns of bidders acquiring private firms owned by families versus the returns of bidders acquiring non-family controlled private firms. The sample consists of 391 acquisitions of private targets in seven continental European countries for the period 1997-2008.

  14. A High Efficiency Variable Gain Amplifier Circuit with Controllable Transconductance Amp

    Science.gov (United States)

    Okura, Tetsuro; Okura, Shunsuke; Ido, Toru; Taniguchi, Kenji

    A novel power reduction technique for a variable gain amplifier (VGA) with a two-stage operational amplifier is proposed. The technique improves the power consumption of a VGA by optimizing the bandwidth and the phase margin dynamically on all gain range of the VGA through controlling the input transconductance of opamp. A VGA utilizing the proposed technique shows 40% reduction of power consumption against a conventional VGA at the best condition of VGA gain range.

  15. Switched-Observer-Based Adaptive Neural Control of MIMO Switched Nonlinear Systems With Unknown Control Gains.

    Science.gov (United States)

    Long, Lijun; Zhao, Jun

    2016-05-02

    In this paper, the problem of adaptive neural output-feedback control is addressed for a class of multi-input multioutput (MIMO) switched uncertain nonlinear systems with unknown control gains. Neural networks (NNs) are used to approximate unknown nonlinear functions. In order to avoid the conservativeness caused by adoption of a common observer for all subsystems, an MIMO NN switched observer is designed to estimate unmeasurable states. A new switched observer-based adaptive neural control technique for the problem studied is then provided by exploiting the classical average dwell time (ADT) method and the backstepping method and the Nussbaum gain technique. It effectively handles the obstacle about the coexistence of multiple Nussbaum-type function terms, and improves the classical ADT method, since the exponential decline property of Lyapunov functions for individual subsystems is no longer satisfied. It is shown that the technique proposed is able to guarantee semiglobal uniformly ultimately boundedness of all the signals in the closed-loop system under a class of switching signals with ADT, and the tracking errors converge to a small neighborhood of the origin. The effectiveness of the approach proposed is illustrated by its application to a two inverted pendulum system.

  16. An application of gain-scheduled control using state-space interpolation to hydroactive gas bearings

    DEFF Research Database (Denmark)

    Theisen, Lukas Roy Svane; Camino, Juan F.; Niemann, Hans Henrik

    2016-01-01

    , it is possible to design a gain-scheduled controller using multiple controllers optimised for a single frequency. Gain-scheduling strategies using the Youla parametrisation can guarantee stability at the cost of increased controller order and performance loss in the interpolation region. This paper contributes...... with a gain-scheduling strategy using state-space interpolation, which avoids both the performance loss and the increase of controller order associated to the Youla parametrisation. The proposed state-space interpolation for gain-scheduling is applied for mass imbalance rejection for a controllable gas...... bearing scheduled in two parameters. Comparisons against the Youla-based scheduling demonstrate the superiority of the state-space interpolation....

  17. Comparison of gradient methods for gain tuning of a PD controller applied on a quadrotor system

    Science.gov (United States)

    Kim, Jinho; Wilkerson, Stephen A.; Gadsden, S. Andrew

    2016-05-01

    Many mechanical and electrical systems have utilized the proportional-integral-derivative (PID) control strategy. The concept of PID control is a classical approach but it is easy to implement and yields a very good tracking performance. Unmanned aerial vehicles (UAVs) are currently experiencing a significant growth in popularity. Due to the advantages of PID controllers, UAVs are implementing PID controllers for improved stability and performance. An important consideration for the system is the selection of PID gain values in order to achieve a safe flight and successful mission. There are a number of different algorithms that can be used for real-time tuning of gains. This paper presents two algorithms for gain tuning, and are based on the method of steepest descent and Newton's minimization of an objective function. This paper compares the results of applying these two gain tuning algorithms in conjunction with a PD controller on a quadrotor system.

  18. Homeostatic bioenergetic network regulation – a novel concept to avoid pharmacoresistance in epilepsy

    Science.gov (United States)

    Boison, Detlev; Masino, Susan A.; Geiger, Jonathan D.

    2011-01-01

    Introduction Despite epilepsy being one of the most prevalent neurological disorders, one third of all patients with epilepsy cannot adequately be treated with available antiepileptic drugs. One of the significant causes for the failure of conventional pharmacotherapeutic treatment is the development of pharmacoresistance in many forms of epilepsy. The problem of pharmacoresistance has called for the development of new conceptual strategies that improve future drug development efforts. Areas covered A thorough review of the recent literature on pharmacoresistance in epilepsy was completed and select examples were chosen to highlight the mechanisms of pharmacoresistance in epilepsy and to demonstrate how those mechanistic findings might lead to improved treatment of pharmacoresistant epilepsy. The reader will gain a thorough understanding of pharmacoresistance in epilepsy and an appreciation of the limitations of conventional drug development strategies. Expert opinion Conventional drug development efforts aim to achieve specificity of symptom control by enhancing the selectivity of drugs acting on specific downstream targets; this conceptual strategy bears the undue risk of development of pharmacoresistance. Modulation of homeostatic bioenergetic network regulation is a novel conceptual strategy to affect whole neuronal networks synergistically by mobilizing multiple endogenous biochemical and receptor-dependent molecular pathways. In our expert opinion we conclude that homeostatic bioenergetic network regulation might thus be used as an innovative strategy for the control of pharmacoresistant seizures. Recent focal adenosine augmentation strategies support the feasibility of this strategy. PMID:21731576

  19. Floquet control of the gain and loss in a PT-symmetric optical coupler

    Science.gov (United States)

    Wu, Yi; Zhu, Bo; Hu, Shu-Fang; Zhou, Zheng; Zhong, Hong-Hua

    2017-02-01

    Controlling the balanced gain and loss in a PT-symmetric system is a rather challenging task. Utilizing Floquet theory, we explore the constructive role of periodic modulation in controlling the gain and loss of a PT-symmetric optical coupler. It is found that the gain and loss of the system can be manipulated by applying a periodic modulation. Further, such an original non-Hermitian system can even be modulated into an effective Hermitian system derived by the high-frequency Floquet method. Therefore, compared with other PT symmetry control schemes, our protocol can modulate the unbroken PT-symmetric range to a wider parameter region. Our results provide a promising approach for controlling the gain and loss of a realistic system.

  20. Effect of Weight Gain on Cardiac Autonomic Control During Wakefulness and Sleep

    Science.gov (United States)

    Adachi, Taro; Sert-Kuniyoshi, Fatima H.; Calvin, Andrew D.; Singh, Prachi; Romero-Corral, Abel; van der Walt, Christelle; Davison, Diane E.; Bukartyk, Jan; Konecny, Tomas; Pusalavidyasagar, Snigdha; Sierra-Johnson, Justo; Somers, Virend K.

    2012-01-01

    Obesity has been associated with increased cardiac sympathetic activation during wakefulness, but the effect on sleep-related sympathetic modulation is not known. The aim of this study was to investigate the effect of fat gain on cardiac autonomic control during wakefulness and sleep in humans. We performed a randomized controlled study to assess the effects of fat gain on heart rate variability (HRV). We recruited 36 healthy volunteers, who were randomized to either a standardized diet to gain approximately 4 kg over 8 weeks followed by an 8 week weight loss period (n=20), or to serve as a weight-maintainer control (n=16). An overnight polysomnogram with power spectral analysis of HRV was performed at baseline, after weight gain, and after weight loss to determine the ratio of low frequency (LF) to high frequency (HF) power, and to examine the relationship between changes in HRV and changes in insulin, leptin and adiponectin levels. Mean weight gain was 3.9 kg in the fat gain group versus 0.1 kg in the maintainer group. LF/HF increased both during wakefulness and sleep after fat gain and returned to baseline after fat loss in the fat gain group, and did not change in the control group. Insulin, leptin and adiponectin also increased after fat gain and fell after fat loss, but no clear pattern of changes were seen that correlated consistently with changes in HRV. Short-term fat gain in healthy subjects is associated with increased cardiac sympathetic activation during wakefulness and sleep but the mechanisms remain unclear. PMID:21357280

  1. Raman-based distributed temperature sensor using simplex code and gain controlled EDFA

    Science.gov (United States)

    Bassan, F. R.; Penze, R. S.; Leonardi, A. A.; Fracarolli, J. P. V.; Floridia, C.; Rosolem, J. B.; Fruett, F.

    2015-09-01

    In this work we present a comparison between simplex coded and optical amplified simplex coded Raman based Distributed Temperature Sensing (DTS). An increase in performance is demonstrated using erbium doped fiber amplifier (EDFA) with proper gain control scheme that allows a DTS operates with simplex code. Using 63-bit simplex code and gain controlled EDFA we demonstrated the temperature resolution and dynamic range improvement in 16 °C @ 10 km and 4 dB, respectively.

  2. Learning to walk with an adaptive gain proportional myoelectric controller for a robotic ankle exoskeleton.

    Science.gov (United States)

    Koller, Jeffrey R; Jacobs, Daniel A; Ferris, Daniel P; Remy, C David

    2015-11-04

    Robotic ankle exoskeletons can provide assistance to users and reduce metabolic power during walking. Our research group has investigated the use of proportional myoelectric control for controlling robotic ankle exoskeletons. Previously, these controllers have relied on a constant gain to map user's muscle activity to actuation control signals. A constant gain may act as a constraint on the user, so we designed a controller that dynamically adapts the gain to the user's myoelectric amplitude. We hypothesized that an adaptive gain proportional myoelectric controller would reduce metabolic energy expenditure compared to walking with the ankle exoskeleton unpowered because users could choose their preferred control gain. We tested eight healthy subjects walking with the adaptive gain proportional myoelectric controller with bilateral ankle exoskeletons. The adaptive gain was updated each stride such that on average the user's peak muscle activity was mapped to maximal power output of the exoskeleton. All subjects participated in three identical training sessions where they walked on a treadmill for 50 minutes (30 minutes of which the exoskeleton was powered) at 1.2 ms(-1). We calculated and analyzed metabolic energy consumption, muscle recruitment, inverse kinematics, inverse dynamics, and exoskeleton mechanics. Using our controller, subjects achieved a metabolic reduction similar to that seen in previous work in about a third of the training time. The resulting controller gain was lower than that seen in previous work (β=1.50±0.14 versus a constant β=2). The adapted gain allowed users more total ankle joint power than that of unassisted walking, increasing ankle power in exchange for a decrease in hip power. Our findings indicate that humans prefer to walk with greater ankle mechanical power output than their unassisted gait when provided with an ankle exoskeleton using an adaptive controller. This suggests that robotic assistance from an exoskeleton can allow

  3. A Uniform Voltage Gain Control for Alignment Robustness in Wireless EV Charging

    Directory of Open Access Journals (Sweden)

    Yabiao Gao

    2015-08-01

    Full Text Available The efficiency of wireless power transfer is sensitive to the horizontal and vertical distances between the transmitter and receiver coils due to the magnetic coupling change. To address the output voltage variation and efficiency drop caused by misalignment, a uniform voltage gain frequency control is implemented to improve the power delivery and efficiency of wireless power transfer under misalignment. The frequency is tuned according to the amplitude and phase-frequency characteristics of coupling variations in order to maintain a uniform output voltage in the receiver coil. Experimental comparison of three control methods, including fixed frequency control, resonant frequency control, and the proposed uniform gain control was conducted and demonstrated that the uniform voltage gain control is the most robust method for managing misalignment in wireless charging applications.

  4. Demonstration of EDFA Cognitive Gain Control via GMPLS for Mixed Modulation Formats in Heterogeneous Optical Networks

    DEFF Research Database (Denmark)

    Oliveira, Juliano R.; Caballero Jambrina, Antonio; Magalhães, Eduardo

    2013-01-01

    We demonstrate cognitive gain control for EDFA operation in real-time GMPLS controlled heterogeneous optical testbed with 10G/100G/200G/400G lightpaths. Cognitive control maintains the network BER below FEC-limit for up to 6 dB of induced attenuation penalty....

  5. Gain-Scheduled Model Predictive Control of Wind Turbines using Laguerre Functions

    DEFF Research Database (Denmark)

    Adegas, Fabiano Daher; Wisniewski, Rafal; Larsen, Lars Finn Sloth

    2014-01-01

    This paper presents a systematic approach to design gain-scheduled predictive controllers for wind turbines. The predictive control law is based on Laguerre functions to parameterize control signals and a parameter-dependent cost function that is analytically determined from turbine data. These p...

  6. Adaptation as a mechanism for gain control in cockroach ON and OFF olfactory receptor neurons.

    Science.gov (United States)

    Burgstaller, Maria; Tichy, Harald

    2012-02-01

    In many sensory systems adaptation acts as a gain control mechanism that optimizes sensory performance by trading increased sensitivity to low stimulus intensity for decreased sensitivity to high stimulus intensity. Adaptation of insect antennal olfactory receptor neurons (ORNs) has been studied for strong odour concentrations, either pulsed or constant. Here, we report that during slowly oscillating changes in the concentration of the odour of lemon oil, the ON and OFF ORNs on the antenna of the cockroach Periplaneta americana adapt to the actual odour concentration and the rate at which concentration changes. When odour concentration oscillates rapidly with brief periods, adaptation improves gain for instantaneous odour concentration and reduces gain for the rate of concentration change. Conversely, when odour concentration oscillates slowly with long periods, adaptation increases gain for the rate of change at the expense of instantaneous concentration. Without this gain control the ON and OFF ORNs would, at brief oscillation periods, soon reach their saturation level and become insensitive to further concentration increments and decrements. At long oscillation periods, on the other hand, the cue would simply be that the discharge begins to change. Because of the high gain for the rate of change, the cockroach will receive creeping changes in odour concentration, even if they persist in one direction. Gain control permits a high degree of precision at small rates when it counts most, without sacrificing the range of detection and without extending the measuring scale.

  7. Gain-controlled erbium-doped fiber amplifier using mode-selective photonic lantern

    Science.gov (United States)

    Lopez-Galmiche, G.; Sanjabi Eznaveh, Z.; Antonio-Lopez, J. E.; Velazquez-Benitez, A. M.; Rodriguez-Asomoza, J.; Herrera-Piad, L. A.; Sanchez-Mondragon, J. J.; Gonent, C.; Sillard, P.; Li, G.; SchuÌlzgen, A.; Okonkwo, C.; Amezcua Correa, R.

    2016-02-01

    For the first time, we demonstrate the implementation of a core pumped few mode erbium amplifier utilizing a mode selective photonic lantern for spatial modal control of the pump light. This device is able to individually amplify the first six fiber modes with low differential modal gain. In addition, we obtained differential modal gain lower than 1 dB and signal gain of approximately 16.17 dB at λs = 1550 nm through forward pumping the LP21 modes at λp = 976 nm.

  8. Motivation by potential gains and losses affects control processes via different mechanisms in the attentional network.

    Science.gov (United States)

    Paschke, Lena M; Walter, Henrik; Steimke, Rosa; Ludwig, Vera U; Gaschler, Robert; Schubert, Torsten; Stelzel, Christine

    2015-05-01

    Attentional control in demanding cognitive tasks can be improved by manipulating the motivational state. Motivation to obtain gains and motivation to avoid losses both usually result in faster reaction times and stronger activation in relevant brain areas such as the prefrontal cortex, but little is known about differences in the underlying neurocognitive mechanisms of these types of motivation in an attentional control context. In the present functional magnetic resonance imaging (fMRI) study, we tested whether potential gain and loss as motivating incentives lead to overlapping or distinct neural effects in the attentional network, and whether one of these conditions is more effective than the other. A Flanker task with word stimuli as targets and distracters was performed by 115 healthy participants. Using a mixed blocked and event-related design allowed us to investigate transient and sustained motivation-related effects. Participants could either gain money (potential gain) or avoid losing money (potential loss) in different task blocks. Participants showed a congruency effect with increased reaction times for incongruent compared to congruent trials. Potential gain led to generally faster responses compared to the neutral condition and to stronger improvements than potential loss. Potential loss also led to shorter response times compared to the neutral condition, but participants improved mainly during incongruent and not during congruent trials. The event-related fMRI data revealed a main effect of congruency with increased activity in the left inferior frontal gyrus (IFG) and inferior frontal junction area (IFJ), the pre-supplementary motor area (pre-SMA), bilateral insula, intraparietal sulcus (IPS) and visual word form area (VWFA). While potential gain led to increased activity in a cluster of the IFJ and the VWFA only during incongruent trials, potential loss was linked to activity increases in these regions during incongruent and congruent trials. The

  9. Adaptive fuzzy dynamic surface control for the chaotic permanent magnet synchronous motor using Nussbaum gain

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Shaohua [School of Automation, Chongqing University, Chongqing 400044, China and College of Mechanical Engineering, Hunan University of Arts and Science, Hunan 415000 (China)

    2014-09-01

    This paper is concerned with the problem of adaptive fuzzy dynamic surface control (DSC) for the permanent magnet synchronous motor (PMSM) system with chaotic behavior, disturbance and unknown control gain and parameters. Nussbaum gain is adopted to cope with the situation that the control gain is unknown. And the unknown items can be estimated by fuzzy logic system. The proposed controller guarantees that all the signals in the closed-loop system are bounded and the system output eventually converges to a small neighborhood of the desired reference signal. Finally, the numerical simulations indicate that the proposed scheme can suppress the chaos of PMSM and show the effectiveness and robustness of the proposed method.

  10. Analysis and design of sliding mode controller gains for boost power factor corrector.

    Science.gov (United States)

    Kessal, Abdelhalim; Rahmani, Lazhar

    2013-09-01

    This paper presents a systematic procedure to compute the gains of sliding mode controller based on an optimization scheme. This controller is oriented to drive an AC-DC converter operating in continuous mode with power factor near unity, and in order to improve static and dynamic performances with large variations of reference voltage and load. This study shows the great influence of the controller gains on the global performances of the system. Hence, a methodology for choosing the gains is detailed. The sliding surface used in this study contains two state variables, input current and output voltage; the advantage of this surface is getting reactions against various disturbances-at the power source, the reference of the output, or the value of the load. The controller is experimentally confirmed for steady-state performance and transient response.

  11. Adaptive fuzzy dynamic surface control for the chaotic permanent magnet synchronous motor using Nussbaum gain

    Science.gov (United States)

    Luo, Shaohua

    2014-09-01

    This paper is concerned with the problem of adaptive fuzzy dynamic surface control (DSC) for the permanent magnet synchronous motor (PMSM) system with chaotic behavior, disturbance and unknown control gain and parameters. Nussbaum gain is adopted to cope with the situation that the control gain is unknown. And the unknown items can be estimated by fuzzy logic system. The proposed controller guarantees that all the signals in the closed-loop system are bounded and the system output eventually converges to a small neighborhood of the desired reference signal. Finally, the numerical simulations indicate that the proposed scheme can suppress the chaos of PMSM and show the effectiveness and robustness of the proposed method.

  12. Reliable gain-scheduled control of discrete-time systems and its application to CSTR model

    Science.gov (United States)

    Sakthivel, R.; Selvi, S.; Mathiyalagan, K.; Shi, Y.

    2016-10-01

    This paper is focused on reliable gain-scheduled controller design for a class of discrete-time systems with randomly occurring nonlinearities and actuator fault. Further, the nonlinearity in the system model is assumed to occur randomly according to a Bernoulli distribution with measurable time-varying probability in real time. The main purpose of this paper is to design a gain-scheduled controller by implementing a probability-dependent Lyapunov function and linear matrix inequality (LMI) approach such that the closed-loop discrete-time system is stochastically stable for all admissible randomly occurring nonlinearities. The existence conditions for the reliable controller is formulated in terms of LMI constraints. Finally, the proposed reliable gain-scheduled control scheme is applied on continuously stirred tank reactor model to demonstrate the effectiveness and applicability of the proposed design technique.

  13. Gain Scheduling Control of Nonlinear Systems Based on Neural State Space Models

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Stoustrup, Jakob

    2003-01-01

    This paper presents a novel method for gain scheduling control of nonlinear systems based on extraction of local linear state space models from neural networks with direct application to robust control. A neural state space model of the system is first trained based on in- and output training...... samples from the system, after which linearized state space models are extracted from the neural network in a number of operating points according to a simple and computationally cheap scheme. Robust observer-based controllers can then be designed in each of these operating points,and gain scheduling...

  14. Adaptive control of linear multivariable systems with high frequency gain matrix hurwitz

    Institute of Scientific and Technical Information of China (English)

    Ying ZHOU; Yuqiang WU; Shumin FEI

    2005-01-01

    A new adaptive control scheme is proposed for multivariable model reference adaptive control(MRAC) systems based on the nonlinear backstepping approach with vector form.The assumption on a priori knowledge of the high frequency gain matrix in existing results is relaxed and the new required condition for the high frequency gain matrix can be easily checked for certain plants so that the proposed method is widely applicable.This control scheme guarantees the global stability of the closed-loop systems and the tracking error can be arbitrary small.The simulation result for an application example shows the validity of the proposed nonlinear adaptive scheme.

  15. Gain-scheduled Linear Quadratic Control of Wind Turbines Operating at High Wind Speed

    DEFF Research Database (Denmark)

    Østergaard, Kasper Zinck; Stoustrup, Jakob; Brath, Per

    2007-01-01

    This paper addresses state estimation and linear quadratic (LQ) control of variable speed variable pitch wind turbines. On the basis of a nonlinear model of a wind turbine, a set of operating conditions is identified and a LQ controller is designed for each operating point. The controller gains....... Simulation results are given that display good performance of the observers and comparisons with a controller designed by classical methods displays the potential of the method.  ...

  16. Homeostatic Plasticity of Subcellular Neuronal Structures: From Inputs to Outputs.

    Science.gov (United States)

    Wefelmeyer, Winnie; Puhl, Christopher J; Burrone, Juan

    2016-10-01

    Neurons in the brain are highly plastic, allowing an organism to learn and adapt to its environment. However, this ongoing plasticity is also inherently unstable, potentially leading to aberrant levels of circuit activity. Homeostatic forms of plasticity are thought to provide a means of controlling neuronal activity by avoiding extremes and allowing network stability. Recent work has shown that many of these homeostatic modifications change the structure of subcellular neuronal compartments, ranging from changes to synaptic inputs at both excitatory and inhibitory compartments to modulation of neuronal output through changes at the axon initial segment (AIS) and presynaptic terminals. Here we review these different forms of structural plasticity in neurons and the effects they may have on network function. Copyright © 2016. Published by Elsevier Ltd.

  17. Noise Temperature Characteristics and Gain-control of Avalanche Photodiodes for Laser Radar

    Institute of Scientific and Technical Information of China (English)

    CAI Xi-ping; SHANG Hong-Bo; BAI Ji-yuan; YANG Shuang; WANG Li-na

    2008-01-01

    Avalanche photodiodes(APDs) are promising light sensors with high quantum efficiency and low noise. It has been extensively used in radiation detection, laser radar and other weak signal detection fields. Unlike other photodiodes, APD is a very sensitive light detector with very high internal gain. The basic theory shows that the gain of APD is related to the temperature. The internal gain fluctuates with the variation of temperature. Investigated was the influence of the variation of the gain induced by the fluctuation of temperature on the output from APD for a very weak laser pulse input in laser radar. An active reverse-biased voltage compensation method is used to stabilize the gain of APD. An APD model is setup to simulate the detection of light pulse signal. The avalanche process, various noises and temperature's effect are all included in the model. Our results show that for the detection of weak light signal such as in laser radar, even a very small fluctuation of temperature could cause a great effect on APD's gain. The results show that the signal-to-noise ratio of the APD's output could be improved effectively with the active gain-control system.

  18. L∞-gain adaptive fuzzy fault accommodation control design for nonlinear time-delay systems.

    Science.gov (United States)

    Wu, Huai-Ning; Qiang, Xiao-Hong; Guo, Lei

    2011-06-01

    In this paper, an adaptive fuzzy fault accommodation (FA) control design with a guaranteed L(∞)-gain performance is developed for a class of nonlinear time-delay systems with persistent bounded disturbances. Using the Lyapunov technique and the Razumikhin-type lemma, the existence condition of the L(∞) -gain adaptive fuzzy FA controllers is provided in terms of linear matrix inequalities (LMIs). In the proposed FA scheme, a fuzzy logic system is employed to approximate the unknown term in the derivative of the Lyapunov function due to the unknown fault function; a continuous-state feedback control strategy is adopted for the control design to avoid the undesirable chattering phenomenon. The resulting FA controllers can ensure that every response of the closed-loop system is uniformly ultimately bounded with a guaranteed L(∞)-gain performance in the presence of a fault. Moreover, by the existing LMI optimization technique, a suboptimal controller is obtained in the sense of minimizing an upper bound of the L(∞)-gain. Finally, the achieved simulation results on the FA control of a continuous stirred tank reactor (CSTR) show the effectiveness of the proposed design procedure.

  19. Adaptive Fuzzy Robust Control for a Class of Nonlinear Systems via Small Gain Theorem

    Directory of Open Access Journals (Sweden)

    Xingjian Wang

    2013-01-01

    Full Text Available Practical nonlinear systems can usually be represented by partly linearizable models with unknown nonlinearities and external disturbances. Based on this consideration, we propose a novel adaptive fuzzy robust control (AFRC algorithm for such systems. The AFRC effectively combines techniques of adaptive control and fuzzy control, and it improves the performance by retaining the advantages of both methods. The linearizable part will be linearly parameterized with unknown but constant parameters, and the discontinuous-projection-based adaptive control law is used to compensate these parts. The Takagi-Sugeno fuzzy logic systems are used to approximate unknown nonlinearities. Robust control law ensures the robustness of closed-loop control system. A systematic design procedure of the AFRC algorithm by combining the backstepping technique and small-gain approach is presented. Then the closed-loop stability is studied by using small gain theorem, and the result indicates that the closed-loop system is semiglobally uniformly ultimately bounded.

  20. Sliding mode control of wind-induced vibrations using fuzzy sliding surface and gain adaptation

    Science.gov (United States)

    Thenozhi, Suresh; Yu, Wen

    2016-04-01

    Although fuzzy/adaptive sliding mode control can reduce the chattering problem in structural vibration control applications, they require the equivalent control and the upper bounds of the system uncertainties. In this paper, we used fuzzy logic to approximate the standard sliding surface and designed a dead-zone adaptive law for tuning the switching gain of the sliding mode control. The stability of the proposed controller is established using Lyapunov stability theory. A six-storey building prototype equipped with an active mass damper has been used to demonstrate the effectiveness of the proposed controller towards the wind-induced vibrations.

  1. Presynaptic gain control by endogenous cotransmission of dopamine and GABA in the olfactory bulb.

    Science.gov (United States)

    Vaaga, Christopher E; Yorgason, Jordan T; Williams, John T; Westbrook, Gary L

    2017-03-01

    In the olfactory bulb, lateral inhibition mediated by local juxtaglomerular interneurons has been proposed as a gain control mechanism, important for decorrelating odorant responses. Among juxtaglomerular interneurons, short axon cells are unique as dual-transmitter neurons that release dopamine and GABA. To examine their intraglomerular function, we expressed channelrhodopsin under control of the DAT-cre promoter and activated olfactory afferents within individual glomeruli. Optical stimulation of labeled cells triggered endogenous dopamine release as measured by cyclic voltammetry and GABA release as measured by whole cell GABAA receptor currents. Activation of short axon cells reduced the afferent presynaptic release probability via D2 and GABAB receptor activation, resulting in reduced spiking in both mitral and external tufted cells. Our results suggest that short axon cells influence glomerular activity not only by direct inhibition of external tufted cells but also by inhibition of afferent inputs to external tufted and mitral cells.NEW & NOTEWORTHY Sensory systems, including the olfactory system, encode information across a large dynamic range, making synaptic mechanisms of gain control critical to proper function. Here we demonstrate that a dual-transmitter interneuron in the olfactory bulb controls the gain of intraglomerular afferent input via two distinct mechanisms, presynaptic inhibition as well as inhibition of a principal neuron subtype, and thereby potently controls the synaptic gain of afferent inputs. Copyright © 2017 the American Physiological Society.

  2. Gain scheduling of aircraft pitch attitude and control of discrete, affine, linear parametrically varying systems

    Science.gov (United States)

    Lin, Zhe

    This research is motivated by gain scheduling, a technique which has been successfully applied to many nonlinear control problems. In flight controls, the wide variations in the characteristics of the aircraft dynamics throughout the flight envelope make gain scheduling a particularly suitable design strategy. This research consists of two parts: (1) aircraft pitch attitude scheduling scheme designs, and (2) control of a class of linear parametrically varying (LPV) systems. In the first part, the classical gain scheduling technique and the single quadratic Lyapunov function (SQLF) based LPV technique are investigated. In the classical gain scheduling design, the Hinfinity mixed sensitivity GS/T method is chosen for local linear time invariant (LTI) designs to provide robustness to unmodeled dynamics and parametric uncertainties. Following a model reduction procedure that exploits the optimal controller structure, LTI controllers designed at the selected equilibrium points are reduced to second order controllers and realized in a feedback path configuration. Such controllers are shown to retain the superior robust performance at each flight condition, while having a low order that is amenable to scheduling. A gain-scheduling law is developed and simulation results verify that the closed-loop performance specifications are met. In the LPV design, the mixed sensitivity S/KS/T design setup is used. An approximation to the original LPV controller using the linear fractional transformation (LFT) representation is constructed. Our design exhibits potential applications of the LPV technique to commercial aircraft gain scheduling designs. In the second part, we consider a class of discrete, affine, linear parametrically varying (DALPV) systems. For this type of systems, the parameters are assumed to vary in a polytope and the state space matrices are assumed to depend affinely on the varying parameters. A sufficient condition is derived to analyze the stability and the

  3. Output feedback adaptive control of multivariable nonlinear systems using Nussbaum gain method

    Institute of Scientific and Technical Information of China (English)

    Zhou Ying; Wu Yuqiang

    2006-01-01

    A new output feedback adaptive control scheme for multi-input and multi-output nonlinear systems with parametric uncertainty is presented based on the Nussbaum gain method and the backstepping approach. The high frequency gain matrix of the linear part of the system is not necessarily positive definite, but can be transformed into a lower or upper triangular matrix whose signs of diagonal elements are unknown. The new required condition for the high frequency gain matrix can be easily checked for certain plants so that the proposed method is widely applicable. The global stability of the closed loop systems is guaranteed through this control scheme, at the same time the tracking error converges to zero.

  4. Operation of a homeostatic sleep switch.

    Science.gov (United States)

    Pimentel, Diogo; Donlea, Jeffrey M; Talbot, Clifford B; Song, Seoho M; Thurston, Alexander J F; Miesenböck, Gero

    2016-08-18

    Sleep disconnects animals from the external world, at considerable risks and costs that must be offset by a vital benefit. Insight into this mysterious benefit will come from understanding sleep homeostasis: to monitor sleep need, an internal bookkeeper must track physiological changes that are linked to the core function of sleep. In Drosophila, a crucial component of the machinery for sleep homeostasis is a cluster of neurons innervating the dorsal fan-shaped body (dFB) of the central complex. Artificial activation of these cells induces sleep, whereas reductions in excitability cause insomnia. dFB neurons in sleep-deprived flies tend to be electrically active, with high input resistances and long membrane time constants, while neurons in rested flies tend to be electrically silent. Correlative evidence thus supports the simple view that homeostatic sleep control works by switching sleep-promoting neurons between active and quiescent states. Here we demonstrate state switching by dFB neurons, identify dopamine as a neuromodulator that operates the switch, and delineate the switching mechanism. Arousing dopamine caused transient hyperpolarization of dFB neurons within tens of milliseconds and lasting excitability suppression within minutes. Both effects were transduced by Dop1R2 receptors and mediated by potassium conductances. The switch to electrical silence involved the downregulation of voltage-gated A-type currents carried by Shaker and Shab, and the upregulation of voltage-independent leak currents through a two-pore-domain potassium channel that we term Sandman. Sandman is encoded by the CG8713 gene and translocates to the plasma membrane in response to dopamine. dFB-restricted interference with the expression of Shaker or Sandman decreased or increased sleep, respectively, by slowing the repetitive discharge of dFB neurons in the ON state or blocking their entry into the OFF state. Biophysical changes in a small population of neurons are thus linked to the

  5. Adaptive Neuro-Fuzzy Based Gain Controller for Erbium-Doped Fiber Amplifiers

    Directory of Open Access Journals (Sweden)

    YUCEL, M.

    2017-02-01

    Full Text Available Erbium-doped fiber amplifiers (EDFA must have a flat gain profile which is a very important parameter such as wavelength division multiplexing (WDM and dense WDM (DWDM applications for long-haul optical communication systems and networks. For this reason, it is crucial to hold a stable signal power per optical channel. For the purpose of overcoming performance decline of optical networks and long-haul optical systems, the gain of the EDFA must be controlled for it to be fixed at a high speed. In this study, due to the signal power attenuation in long-haul fiber optic communication systems and non-equal signal amplification in each channel, an automatic gain controller (AGC is designed based on the adaptive neuro-fuzzy inference system (ANFIS for EDFAs. The intelligent gain controller is implemented and the performance of this new electronic control method is demonstrated. The proposed ANFIS-based AGC-EDFA uses the experimental dataset to produce the ANFIS-based sets and the rule base. Laser diode currents are predicted within the accuracy rating over 98 percent with the proposed ANFIS-based system. Upon comparing ANFIS-based AGC-EDFA and experimental results, they were found to be very close and compatible.

  6. Matching Automatic Gain Control Across Devices in Bimodal Cochlear Implant Users

    NARCIS (Netherlands)

    Veugen, L.C.E.; Chalupper, J.; Snik, A.F.M.; Opstal, A.J. van; Mens, L.H.M.

    2016-01-01

    OBJECTIVES: The purpose of this study was to improve bimodal benefit in listeners using a cochlear implant (CI) and a hearing aid (HA) in contralateral ears, by matching the time constants and the number of compression channels of the automatic gain control (AGC) of the HA to the CI. Equivalent AGC

  7. Adipose Tissue Remodeling as Homeostatic Inflammation

    Directory of Open Access Journals (Sweden)

    Michiko Itoh

    2011-01-01

    Full Text Available Evidence has accumulated indicating that obesity is associated with a state of chronic, low-grade inflammation. Obese adipose tissue is characterized by dynamic changes in cellular composition and function, which may be referred to as “adipose tissue remodeling”. Among stromal cells in the adipose tissue, infiltrated macrophages play an important role in adipose tissue inflammation and systemic insulin resistance. We have demonstrated that a paracrine loop involving saturated fatty acids and tumor necrosis factor-α derived from adipocytes and macrophages, respectively, aggravates obesity-induced adipose tissue inflammation. Notably, saturated fatty acids, which are released from hypertrophied adipocytes via the macrophage-induced lipolysis, serve as a naturally occurring ligand for Toll-like receptor 4 complex, thereby activating macrophages. Such a sustained interaction between endogenous ligands derived from parenchymal cells and pathogen sensors expressed in stromal immune cells should lead to chronic inflammatory responses ranging from the basal homeostatic state to diseased tissue remodeling, which may be referred to as “homeostatic inflammation”. We, therefore, postulate that adipose tissue remodeling may represent a prototypic example of homeostatic inflammation. Understanding the molecular mechanism underlying homeostatic inflammation may lead to the identification of novel therapeutic strategies to prevent or treat obesity-related complications.

  8. Adaptive-Gain Second-Order Sliding Mode Control of Attitude Tracking of Flexible Spacecraft

    Directory of Open Access Journals (Sweden)

    Chutiphon Pukdeboon

    2014-01-01

    finite-time second-order sliding mode control algorithms are presented to solve this problem. For the first controller, a novel second-order sliding mode control scheme is developed to achieve high-precision tracking performance. For the second control law, an adaptive-gain second-order sliding mode control algorithm combing an adaptive law with second-order sliding mode control strategy is designed to relax the requirement of prior knowledge of the bound of the system uncertainties. The rigorous proofs show that the proposed controllers provide finite-time convergence of the attitude and angular velocity tracking errors. Numerical simulations on attitude tracking control are presented to demonstrate the performance of the developed controllers.

  9. LNA with wide range of gain control and wideband interference rejection

    Science.gov (United States)

    Wang, Jhen-Ji; Chen, Duan-Yu

    2016-10-01

    This work presents a low-noise amplifier (LNA) design with a wide-range gain control characteristic that integrates adjustable current distribution and output impedance techniques. For a given gain characteristic, the proposed LNA provides better wideband interference rejection performance than conventional LNA. Moreover, the proposed LNA also has a wider gain control range than conventional LNA. Therefore, it is suitable for satellite communications systems. The simulation results demonstrate that the voltage gain control range is between 14.5 and 34.2 dB for such applications (2600 MHz); the input reflection coefficient is less than -18.9 dB; the noise figure (NF) is 1.25 dB; and the third-order intercept point (IIP3) is 4.52 dBm. The proposed LNA consumes 23.85-28.17 mW at a supply voltage of 1.8 V. It is implemented by using TSMC 0.18-um RF CMOS process technology.

  10. Visual information gain and task asymmetry interact in bimanual force coordination and control.

    Science.gov (United States)

    Hu, Xiaogang; Newell, Karl M

    2011-08-01

    This study examined the question of whether and how the influence of visual information on force coordination patterns is dependent on the settings of a task asymmetry constraint. In a bimanual isometric force experiment, the task asymmetry was manipulated via imposing different coefficients on the index finger forces such that the weighted sum of the finger forces matched the target force. The environmental constraint was quantified by the visual performance error and was manipulated through the change of visual gain (number of pixels on the screen representing the unit of force). The constraint arising from the individual was quantified by the bilateral coupling effect (i.e., symmetric force production) between hands. The results revealed improved performance in terms of lower variability and performance error and more complex total force structure with higher visual gain. The influence of visual gain on the force coordination pattern, however, was found to be dependent on the task coefficients imposed on the finger forces. Namely, the force sharing between hands became more symmetric with high visual gain only when the right finger force had the higher coefficient, and an error-compensatory strategy was evident with high gain only when symmetric coefficients were imposed on the two fingers. The findings support the proposition that the motor coordination and control patterns are organized by the interactive influence of different categories of constraints where the functional influence of the information provided is dependent on the motor output.

  11. Adaptive Robust Actuator Fault Accommodation for a Class of Uncertain Nonlinear Systems with Unknown Control Gains

    Directory of Open Access Journals (Sweden)

    Yuefei Wu

    2014-01-01

    Full Text Available An adaptive robust fault tolerant control approach is proposed for a class of uncertain nonlinear systems with unknown signs of high-frequency gain and unmeasured states. In the recursive design, neural networks are employed to approximate the unknown nonlinear functions, K-filters are designed to estimate the unmeasured states, and a dynamical signal and Nussbaum gain functions are introduced to handle the unknown sign of the virtual control direction. By incorporating the switching function σ algorithm, the adaptive backstepping scheme developed in this paper does not require the real value of the actuator failure. It is mathematically proved that the proposed adaptive robust fault tolerant control approach can guarantee that all the signals of the closed-loop system are bounded, and the output converges to a small neighborhood of the origin. The effectiveness of the proposed approach is illustrated by the simulation examples.

  12. A novel analog/digital reconfigurable automatic gain control with a novel DC offset cancellation circuit*

    Institute of Scientific and Technical Information of China (English)

    He Xiaofeng; Mo Taishan; Ma Chengyan; Ye Tianchun

    2011-01-01

    An analog/digital reconfigurable automatic gain control (AGC) circuit with a novel DC offset cancellation circuit for a direct-conversion receiver is presented. The AGC is analog/digital reconfigurable in order to be compatible with different baseband chips. What's more, a novel DC offset cancellation (DCOC) circuit with an HPCF (high pass cutoff frequency) less than 10 kHz is proposed. The AGC is fabricated by a 0.18 μm CMOS process. Under analog control mode, the AGC achieves a 70 dB dynamic range with a 3 dB-bandwidth larger than 60 MHz. Under digital control mode, through a 5-bit digital control word, the AGC shows a 64 dB gain control range by 2 dB each step with a gain error of less than 0.3 dB. The DC offset cancellation circuits can suppress the output DC offset voltage to be less than 1.5 mV, while the offset voltage of 40 mV is introduced into the input. The overall power consumption is less than 3.5 mA, and the die area is 800 × 300μm2.

  13. Auto gain control of EMCCD in Shack-Hartmann wavefront sensor for adaptive optics

    Science.gov (United States)

    Zhu, Zhaoyi; Li, Dayu; Hu, Lifa; Mu, QuanQuan; Cao, Zhaoliang; Wang, Yukun; Wang, Shaoxin; Xuan, Li

    2016-12-01

    Electron multiplying charge-coupled-device (EMCCD) applied in Shack-Hartmann wavefront sensor (S-H WFS) makes the wavefront sensing more efficient for adaptive optics (AO). However when the brightness of the observed target changes in large ranges in a few minutes, a fixed electron multiplying (EM) gain may not be optimum. Thus an auto-gain-control (AGC) method based on the spots image of the S-H WFS is proposed. The designed control value is the average value of the maximum signals of all the light spots in a frame. It has been demonstrated in the experiments that the control value is sensitive to the change of the target brightness, and is stable in the presence of detecting noises and turbulence influence. The goal value for control is predetermined based on the linear relation of the signal with the EM gain and the number of photons collected in sub-apertures. The conditions of the self-protection of the EMCCD are also considered for the goal value. Simulations and experiments indicate that the proposed control method is efficient, and keeps the sensing in a high SNR which reaches the upper SNR limit when sensing with EMCCD. The self-protection of the EMCCD is avoided during the whole sensing process.

  14. An improved test for detecting multiplicative homeostatic synaptic scaling.

    Directory of Open Access Journals (Sweden)

    Jimok Kim

    Full Text Available Homeostatic scaling of synaptic strengths is essential for maintenance of network "gain", but also poses a risk of losing the distinctions among relative synaptic weights, which are possibly cellular correlates of memory storage. Multiplicative scaling of all synapses has been proposed as a mechanism that would preserve the relative weights among them, because they would all be proportionately adjusted. It is crucial for this hypothesis that all synapses be affected identically, but whether or not this actually occurs is difficult to determine directly. Mathematical tests for multiplicative synaptic scaling are presently carried out on distributions of miniature synaptic current amplitudes, but the accuracy of the test procedure has not been fully validated. We now show that the existence of an amplitude threshold for empirical detection of miniature synaptic currents limits the use of the most common method for detecting multiplicative changes. Our new method circumvents the problem by discarding the potentially distorting subthreshold values after computational scaling. This new method should be useful in assessing the underlying neurophysiological nature of a homeostatic synaptic scaling transformation, and therefore in evaluating its functional significance.

  15. Design principles for the analysis and construction of robustly homeostatic biological networks.

    Science.gov (United States)

    Tang, Zhe F; McMillen, David R

    2016-11-07

    Homeostatic biological systems resist external disturbances, allowing cells and organisms to maintain a constant internal state despite perturbations from their surroundings. Many biological regulatory networks are known to act homeostatically, with examples including thermal adaptation, osmoregulation, and chemotaxis. Understanding the network topologies (sets of regulatory interactions) and biological parameter regimes that can yield homeostasis in a biological system is of interest both for the study of natural biological system, and in the context of designing new biological control schemes for use in synthetic biology. Here, we examine the mathematical properties of a function that maps a biological system's inputs to its outputs, we have formulated a novel criterion (the "cofactor condition") that compactly describes the conditions for homeostasis. We further analyze the problem of robust homeostasis, wherein the system is required to maintain homeostatic behavior when its parameter values are slightly altered. We use the cofactor condition to examine previously reported examples of robust homeostasis, showing that it is a useful way to unify a number of seemingly different analyses into a single framework. Based on the observation that all previous robustly homeostatic examples fall into one of three classes, we propose a "strong cofactor condition" and use it to provide an algorithm for designing new robustly homeostatic biological networks, giving both their topologies and constraints on their parameter values. Applying the design algorithm to a three-node biological network, we construct several robustly homeostatic genetic networks, uncovering network topologies not previously identified as candidates for exhibiting robust homeostasis.

  16. Effect of olive oil massage on weight gain in preterm infants: A randomized controlled clinical trial

    Directory of Open Access Journals (Sweden)

    Mahnaz Jabraeile

    2016-01-01

    Full Text Available Background: Despite the fact that effect of massage with or without oil on the baby′s weight gain is not clear, but recent studies have shown that massage with essential oils make lipid absorption through the skin. The aim of this study was to evaluate the effect of olive oil massage on weight gain in preterm infants. Materials and Methods: This study was a single-blind, randomized controlled clinical trial. In this study, infants who met inclusion criteria for the study were divided into two groups by using random numbers table. Newborns in intervention group were under massage for 10 days and 3 times for 15 min daily; the mother of these newborns had been trained already using olive oil. Moreover, the infants of the control group were under massaging without oil same as the above-mentioned method. Researchers weighed babies daily during 10 days and recorded it at the checklist. Data from the study were reviewed and analyzed by descriptive statistics and repeated measure test using the statistical software SPSS/13. Results: This study showed that the neonatal weight gain in the infants with the oil massage was 21 g daily in average, whereas the increase in infant massage without oil was 7 g. This difference was statistically significant (P < 0.001. Conclusion: Considering the positive effect of infant massage on weight gain in premature infants with olive oil, it is recommended that nurses use oil in infant massage in the neonatal units.

  17. Decentralized PI/PID controllers based on gain and phase margin specifications for TITO processes.

    Science.gov (United States)

    Maghade, D K; Patre, B M

    2012-07-01

    In this paper, a decentralized PI/PID controller design method based on gain and phase margin specifications for two-input-two-output (TITO) interactive processes is proposed. The decouplers are designed for systems to minimize the interaction between the loops, and the first order plus dead time (FOPDT) model is achieved for each decoupled subsystem based on the frequency response fitting. An independent PI/PID controller is designed for each reduced order decoupled subsystem to obtain the desired gain and phase margins, and the performance is verified on the original interactive system to show the effectiveness of the proposed design method for the general class of TITO systems. Simulation examples are incorporated to validate the usefulness of the presented algorithm. An experimentation is performed on the Level-Temperature reactor process to show the practical applicability of the proposed method for the interactive system.

  18. Homeostatic regulation of sleep in arrhythmic Siberian hamsters.

    Science.gov (United States)

    Larkin, Jennie E; Yokogawa, Tohei; Heller, H Craig; Franken, Paul; Ruby, Norman F

    2004-07-01

    Sleep is regulated by independent yet interacting circadian and homeostatic processes. The present study used a novel approach to study sleep homeostasis in the absence of circadian influences by exposing Siberian hamsters to a simple phase delay of the photocycle to make them arrhythmic. Because these hamsters lacked any circadian organization, their sleep homeostasis could be studied in the absence of circadian interactions. Control animals retained circadian rhythmicity after the phase shift and re-entrained to the phase-shifted photocycle. These animals displayed robust daily sleep-wake rhythms with consolidated sleep during the light phase beginning about 1 h after light onset. This marked sleep-wake pattern was circadian in that it persisted in constant darkness. The distribution of sleep in the arrhythmic hamsters over 24 h was similar to that in the light phase of rhythmic animals. Therefore, daily sleep amounts were higher in arrhythmic animals compared with rhythmic ones. During 2- and 6-h sleep deprivations (SD), it was more difficult to keep arrhythmic hamsters awake than it was for rhythmic hamsters. Because the arrhythmic animals obtained more non-rapid eye movement sleep (NREMS) during the SD, they showed a diminished compensatory response in NREMS EEG slow-wave activity during recovery sleep. When amounts of sleep during the SD were taken into account, there were no differences in sleep homeostasis between experimental and control hamsters. Thus loss of circadian control did not alter the homeostatic response to SD. This supports the view that circadian and homeostatic influences on sleep regulation are independent processes.

  19. Homeostatic regulation of memory systems and adaptive decisions.

    Science.gov (United States)

    Mizumori, Sheri J Y; Jo, Yong Sang

    2013-11-01

    While it is clear that many brain areas process mnemonic information, understanding how their interactions result in continuously adaptive behaviors has been a challenge. A homeostatic-regulated prediction model of memory is presented that considers the existence of a single memory system that is based on a multilevel coordinated and integrated network (from cells to neural systems) that determines the extent to which events and outcomes occur as predicted. The "multiple memory systems of the brain" have in common output that signals errors in the prediction of events and/or their outcomes, although these signals differ in terms of what the error signal represents (e.g., hippocampus: context prediction errors vs. midbrain/striatum: reward prediction errors). The prefrontal cortex likely plays a pivotal role in the coordination of prediction analysis within and across prediction brain areas. By virtue of its widespread control and influence, and intrinsic working memory mechanisms. Thus, the prefrontal cortex supports the flexible processing needed to generate adaptive behaviors and predict future outcomes. It is proposed that prefrontal cortex continually and automatically produces adaptive responses according to homeostatic regulatory principles: prefrontal cortex may serve as a controller that is intrinsically driven to maintain in prediction areas an experience-dependent firing rate set point that ensures adaptive temporally and spatially resolved neural responses to future prediction errors. This same drive by prefrontal cortex may also restore set point firing rates after deviations (i.e. prediction errors) are detected. In this way, prefrontal cortex contributes to reducing uncertainty in prediction systems. An emergent outcome of this homeostatic view may be the flexible and adaptive control that prefrontal cortex is known to implement (i.e. working memory) in the most challenging of situations. Compromise to any of the prediction circuits should result in

  20. Distributed temperature sensing system using a commercial OTDR and a standard EDFA with controlled gain

    Science.gov (United States)

    Bassan, Fabio R.; Salgado, Felipe C.; Fruett, Fabiano; Rosolem, Joao B.

    2016-05-01

    The distributed temperature sensor system based in the spontaneous Raman backscattering is demonstrated for the first time to our knowledge, using a commercial OTDR (Optical Time Domain Reflectometer) and a standard erbium doped fiber amplifier (EDFA) with controlled gain. We evaluated this approach in a 30 km of single mode fiber using an OTDR pulse width of 100 ns and an EDFA with 17 dBm of output power.

  1. Gain transient control for wavelength division multiplexed access networks using semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Gibbon, Timothy Braidwood; Osadchiy, Alexey Vladimirovich; Kjær, Rasmus;

    2009-01-01

    measurements how a near-saturated semiconductor optical amplifier (SOA) can be used to control these gain transients. An SOA is shown to reduce the penalty of transients originating in an EDFA from 2.3 dB to 0.2 dB for 10 Gb/s transmission over standard single mode fiber using a 231-1 PRBS pattern. The results...

  2. Adaptive gain control for spike-based map communication in a neuromorphic vision system.

    Science.gov (United States)

    Meng, Yicong; Shi, Bertram E

    2008-06-01

    To support large numbers of model neurons, neuromorphic vision systems are increasingly adopting a distributed architecture, where different arrays of neurons are located on different chips or processors. Spike-based protocols are used to communicate activity between processors. The spike activity in the arrays depends on the input statistics as well as internal parameters such as time constants and gains. In this paper, we investigate strategies for automatically adapting these parameters to maintain a constant firing rate in response to changes in the input statistics. We find that under the constraint of maintaining a fixed firing rate, a strategy based upon updating the gain alone performs as well as an optimal strategy where both the gain and the time constant are allowed to vary. We discuss how to choose the time constant and propose an adaptive gain control mechanism whose operation is robust to changes in the input statistics. Our experimental results on a mobile robotic platform validate the analysis and efficacy of the proposed strategy.

  3. Modeling lateral geniculate nucleus response with contrast gain control. Part 2: analysis.

    Science.gov (United States)

    Cope, Davis; Blakeslee, Barbara; McCourt, Mark E

    2014-02-01

    Cope et al. [J. Opt. Soc. Am. A30, 2401 (2013)] proposed a class of models for lateral geniculate nucleus (LGN) ON-cell behavior consisting of a linear response with divisive normalization by local stimulus contrast. Here, we analyze a specific model with the linear response defined by a difference-of-Gaussians filter, and a circular Gaussian for the gain pool weighting function. For sinusoidal grating stimuli, the parameter region for bandpass behavior of the linear response is determined, and the gain control response is shown to act as a switch (changing from "off" to "on" with increasing spatial frequency). It is also shown that large gain pools stabilize the optimal spatial frequency of the total nonlinear response at a fixed value independent of contrast and stimulus magnitude. Under- and super-saturation, as well as contrast saturation, occur as typical effects of stimulus magnitude. For circular spot stimuli, it is shown that large gain pools stabilize the spot size that yields the maximum response.

  4. Integrating Hebbian and homeostatic plasticity: introduction.

    Science.gov (United States)

    Fox, Kevin; Stryker, Michael

    2017-03-05

    Hebbian plasticity is widely considered to be the mechanism by which information can be coded and retained in neurons in the brain. Homeostatic plasticity moves the neuron back towards its original state following a perturbation, including perturbations produced by Hebbian plasticity. How then does homeostatic plasticity avoid erasing the Hebbian coded information? To understand how plasticity works in the brain, and therefore to understand learning, memory, sensory adaptation, development and recovery from injury, requires development of a theory of plasticity that integrates both forms of plasticity into a whole. In April 2016, a group of computational and experimental neuroscientists met in London at a discussion meeting hosted by the Royal Society to identify the critical questions in the field and to frame the research agenda for the next steps. Here, we provide a brief introduction to the papers arising from the meeting and highlight some of the themes to have emerged from the discussions.This article is part of the themed issue 'Integrating Hebbian and homeostatic plasticity'. © 2017 The Author(s).

  5. Preventing Weight Gain in Women in Rural Communities: A Cluster Randomised Controlled Trial.

    Directory of Open Access Journals (Sweden)

    Catherine Lombard

    2016-01-01

    Full Text Available Obesity is reaching epidemic proportions in both developed and developing countries. Even modest weight gain increases the risk for chronic illness, yet evidence-based interventions to prevent weight gain are rare. This trial will determine if a simple low-intensity intervention can prevent weight gain in women compared to general health information.We conducted a 1-yr pragmatic, cluster randomised controlled trial in 41 Australian towns (clusters randomised using a computer-generated randomisation list for intervention (n = 21 or control (n = 20. Women aged 18 to 50 yr were recruited from the general population to receive a 1-yr self-management lifestyle intervention (HeLP-her consisting of one group session, monthly SMS text messages, one phone coaching session, and a program manual, or to a control group receiving one general women's health education session. From October 2012 to April 2014 we studied 649 women, mean age 39.6 yr (+/- SD 6.7 and BMI of 28.8 kg/m(2 (+/- SD 6.9 with the primary outcome weight change between groups at 1 yr. The mean change in the control was +0.44 kg (95% CI -0.09 to 0.97 and in the intervention group -0.48 kg (95% CI -0.99 to 0.03 with an unadjusted between group difference of -0.92 kg (95% CI -1.67 to -0.16 or -0.87 kg (95% CI -1.62 to -0.13 adjusted for baseline values and clustering. Secondary outcomes included improved diet quality and greater self-management behaviours. The intervention appeared to be equally efficacious across all age, BMI, income, and education subgroups. Loss to follow-up included 23.8% in the intervention group and 21.8% in the control group and was within the anticipated range. Limitations include lack of sensitive tools to measure the small changes to energy intake and physical activity. Those who gained weight may have been less inclined to return for 1 yr weight measures.A low intensity lifestyle program can prevent the persistent weight gain observed in women. Key features included

  6. New Gain Controllable Resistor-less Current-mode First Order Allpass Filter and its Application

    Directory of Open Access Journals (Sweden)

    W. Jaikla

    2012-04-01

    Full Text Available New first order allpass filter (APF in current mode, constructed from 2 CCCCTAs and grounded capacitor, is presented. The current gain and phase shift can be electronically /orthogonally controlled. Low input and high output impedances are achieved which make the circuit to be easily cascaded to the current-mode circuit without additional current buffers. The operation of the proposed filter has been verified through simulation results which confirm the theoretical analysis. The application example as current-mode quadrature oscillator with non-interactive current control for both of oscillation condition and oscillation frequency is included to show the usability of the proposed filter.

  7. Robust Model Predictive Control of a Nonlinear System with Known Scheduling Variable and Uncertain Gain

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Poulsen, Niels Kjølstad; Niemann, Hans Henrik

    2012-01-01

    Robust model predictive control (RMPC) of a class of nonlinear systems is considered in this paper. We will use Linear Parameter Varying (LPV) model of the nonlinear system. By taking the advantage of having future values of the scheduling variable, we will simplify state prediction. Because...... of the special structure of the problem, uncertainty is only in the B matrix (gain) of the state space model. Therefore by taking advantage of this structure, we formulate a tractable minimax optimization problem to solve robust model predictive control problem. Wind turbine is chosen as the case study and we...

  8. Extremum-seeking with variable gain control for intensifying biogas production in anaerobic fermentation.

    Science.gov (United States)

    Liu, J; Olsson, G; Mattiasson, B

    2006-01-01

    A state-dependent variable-gain control system is implemented to follow the characteristics of a laboratory-scale up-flow anaerobic fixed-bed reactor dynamically. The transition from one state to another is determined on an hourly basis, depending on difference between the setpoint of the reactor pH and its true value. Considerable improvement of the process stability--reduction of oscillation in both the reactor pH and biogas production rate during high-rate operation, has been achieved, although the control structure is simple and intuitive.

  9. A novel analog power supply for gain control of the Multi-Pixel Photon Counter (MPPC)

    Science.gov (United States)

    Li, Zhengwei; Liu, Congzhan; Xu, Yupeng; Yan, Bo; Li, Yanguo; Lu, Xuefeng; Li, Xufang; Zhang, Shuo; Chang, Zhi; Li, Jicheng; Gao, He; Zhang, Yifei; Zhao, Jianling

    2017-04-01

    Silicon Photo-Multipliers (SiPM) are regarded as novel photo-detectors to replace conventional Photo-Multiplier Tubes (PMTs). However, the breakdown voltage dependence on the ambient temperature results in a gain variation of ∼3%/°C. This severely limits the application of this device in experiments with wide range of operating temperature, especially in space missions. An experimental setup was established to investigate the temperature and bias voltage dependence of gain for the Multi-Pixel Photon Counter (MPPC). The gain and breakdown voltage dependence on operating temperature of an MPPC can be approximated by a linear function, which is similar to the behavior of a zener diode. The measured temperature coefficient of the breakdown voltage is (59.4±0.4 mV)/°C. According to this fact, an analog power supply based on two zener diodes and an operational amplifier was designed with a positive temperature coefficient. The measured temperature dependence for the designed power supply is between 63.65-64.61 mV/°C at different output voltages. The designed power supply can bias the MPPC at an over-voltage with a temperature variation of ∼5 mV/°C. The gain variation of the MPPC biased at over-voltage of 2 V was reduced from 2.8 % / ° C to 0.3 % / ° C when biased the MPPC with the designed power supply for gain control. Detailed design and performance of the analog power supply in the temperature range from - 42.7 ° C to 20.9 ° C will be discussed in this paper.

  10. Distributed adaptive output consensus control of second-order systems containing unknown non-linear control gains

    Science.gov (United States)

    Wang, Gang; Wang, Chaoli; Du, Qinghui; Cai, Xuan

    2016-10-01

    In this paper, we address the output consensus problem of tracking a desired trajectory for a group of second-order agents on a directed graph with a fixed topology. Each agent is modelled by a second-order non-linear system with unknown non-linear dynamics and unknown non-linear control gains. Only a subset of the agents is given access to the desired trajectory information directly. A distributed adaptive consensus protocol driving all agents to track the desired trajectory is presented using the backstepping technique and approximation technique of Fourier series (FSs). The FS structure is taken not only for tracking the non-linear dynamics but also the unknown portion in the controller design procedure, which can avoid virtual controllers containing the uncertain terms. Stability analysis and parameter convergence of the proposed algorithm are conducted based on the Lyapunov theory and the algebraic graph theory. It is also demonstrated that arbitrary small tracking errors can be achieved by appropriately choosing design parameters. Though the proposed work is applicable for second-order non-linear systems containing unknown non-linear control gains, the proposed controller design can be easily extended to higher-order non-linear systems containing unknown non-linear control gains. Simulation results show the effectiveness of the proposed schemes.

  11. Design of Constant Gain Dissipative Controllers for Eigensystem Assignment in Passive Systems

    Science.gov (United States)

    Maghami, Peiman G.; Gupta, Sandeep

    1998-01-01

    Partial eigensystem assignment with output feedback can lead to an unstable closed-loop system. However, output feedback with passive linear time-invariant systems, such as flexible space structures, is guaranteed to be stable if the controller is dissipative. This paper presents a novel approach for synthesis of dissipative output feedback gain matrices for assigning a selected number of closed-loop poles. Dissipativity of a gain matrix is known to be equivalent to positive semidefiniteness of the symmetric part of the matrix. A sequential procedure is presented to assign one self-conjugate pair of closed-loop eigenvalues at each step using dissipative output feedback gain matrices, while ensuring that the eigenvalues assigned in the previous steps are not disturbed. The problem of assigning one closed-loop pair is reduced to a constrained solution of a system of quadratic equations, and necessary and sufficient conditions for the existence of a solution are presented. A minimax approach is presented for determining parameters which satisfy these conditions. This method can assign as many closed-loop system poles as the number of control inputs. A numerical example of damping enhancement for a flexible structure is presented to demonstrate the approach.

  12. Determinants of rapid weight gain during infancy: baseline results from the NOURISH randomised controlled trial

    Directory of Open Access Journals (Sweden)

    Mihrshahi Seema

    2011-11-01

    Full Text Available Abstract Background Rapid weight gain in infancy is an important predictor of obesity in later childhood. Our aim was to determine which modifiable variables are associated with rapid weight gain in early life. Methods Subjects were healthy infants enrolled in NOURISH, a randomised, controlled trial evaluating an intervention to promote positive early feeding practices. This analysis used the birth and baseline data for NOURISH. Birthweight was collected from hospital records and infants were also weighed at baseline assessment when they were aged 4-7 months and before randomisation. Infant feeding practices and demographic variables were collected from the mother using a self administered questionnaire. Rapid weight gain was defined as an increase in weight-for-age Z-score (using WHO standards above 0.67 SD from birth to baseline assessment, which is interpreted clinically as crossing centile lines on a growth chart. Variables associated with rapid weight gain were evaluated using a multivariable logistic regression model. Results Complete data were available for 612 infants (88% of the total sample recruited with a mean (SD age of 4.3 (1.0 months at baseline assessment. After adjusting for mother's age, smoking in pregnancy, BMI, and education and infant birthweight, age, gender and introduction of solid foods, the only two modifiable factors associated with rapid weight gain to attain statistical significance were formula feeding [OR = 1.72 (95%CI 1.01-2.94, P = 0.047] and feeding on schedule [OR = 2.29 (95%CI 1.14-4.61, P = 0.020]. Male gender and lower birthweight were non-modifiable factors associated with rapid weight gain. Conclusions This analysis supports the contention that there is an association between formula feeding, feeding to schedule and weight gain in the first months of life. Mechanisms may include the actual content of formula milk (e.g. higher protein intake or differences in feeding styles, such as feeding to schedule

  13. WGC Based Robust and Gain Scheduling PI Controller Design for Condensing Boilers

    Directory of Open Access Journals (Sweden)

    Cem Onat

    2014-05-01

    Full Text Available This paper addresses the water temperature PI control in condensing domestic boilers. The main challenge of this process under the controller design perspective is the fact that the dynamics of condensing boilers are strongly affected by the demanded water flow rate. First, a robust PI controller based on weighted geometrical center method is designed that stabilizes and achieves good performance for closed-loop system for a wide range of the water flow rate. Then, it is shown that if the water flow rate information is used to update the controller gains, through a technique known as gain scheduled control, the performance can be significantly improved. Important characteristics of these PI design approaches are that the resulting parameters are calculated numerically without using any graphical method or iterative optimization process and that it guarantees the stability of the closed-loop. Significantly, simulation results have demonstrated that the proposed tuning techniques can perform better for set point changes and load disturbance than other available methods in the literature.

  14. SEMICONDUCTOR INTEGRATED CIRCUITS: A low power automatic gain control loop for a receiver

    Science.gov (United States)

    Guofeng, Li; Zhiqing, Geng; Nanjian, Wu

    2010-09-01

    This paper proposes a new structure to lower the power consumption of a variable gain amplifier (VGA) and keep the linearity of the VGA unchanged. The structure is used in a high rate amplitude-shift keying (ASK) based IF-stage. It includes an automatic gain control (AGC) loop and ASK demodulator. The AGC mainly consists of six-stage VGAs. The IF-stage is realized in 0.18 μm CMOS technology. The measurement results show that the power consumption of the whole system is very low. The system consumes 730 μA while operating at 1.8 V. The minimum ASK signal the system could detect is 0.7 mV (peak to peak amplitude).

  15. A small-gain method for integrated guidance and control in terminal phase of reentry

    Science.gov (United States)

    Yan, Han; Tan, Shuping; He, Yingzi

    2017-03-01

    The guidance and control systems of reentry vehicles are usually designed separately and then integrated, but the scheme can be argued that synergistic relationships between the two subsystems are not fully exploited. In order to improve the performance of reusable launch vehicles (RLVs), this paper proposes an integrated guidance and control law for approach and landing of a RLV. According to the idea of reference-trajectory guidance, the angle of attack and bank angle commands are designed using sliding mode control (SMC) method to make the reference-trajectory tacking error converge into a small neighborhood of zero. An integrated guidance and control (IGC) law is developed utilizing generalized small-gain theorem to enforce the commands, and theoretical analysis shows that the law can guarantee the stability of the overall system. The Monte Carlo simulation confirms the effectiveness of the proposed design approach.

  16. Redesign of a Variable-Gain Output Feedback Longitudinal Controller Flown on the High-Alpha Research Vehicle (HARV)

    Science.gov (United States)

    Ostroff, Aaron J.

    1998-01-01

    This paper describes a redesigned longitudinal controller that flew on the High-Alpha Research Vehicle (HARV) during calendar years (CY) 1995 and 1996. Linear models are developed for both the modified controller and a baseline controller that was flown in CY 1994. The modified controller was developed with three gain sets for flight evaluation, and several linear analysis results are shown comparing the gain sets. A Neal-Smith flying qualities analysis shows that performance for the low- and medium-gain sets is near the level 1 boundary, depending upon the bandwidth assumed, whereas the high-gain set indicates a sensitivity problem. A newly developed high-alpha Bode envelope criterion indicates that the control system gains may be slightly high, even for the low-gain set. A large motion-base simulator in the United Kingdom was used to evaluate the various controllers. Desired performance, which appeared to be satisfactory for flight, was generally met with both the low- and medium-gain sets. Both the high-gain set and the baseline controller were very sensitive, and it was easy to generate pilot-induced oscillation (PIO) in some of the target-tracking maneuvers. Flight target-tracking results varied from level 1 to level 3 and from no sensitivity to PIO. These results were related to pilot technique and whether actuator rate saturation was encountered.

  17. Homeostatic plasticity of striatal neurons intrinsic excitability following dopamine depletion.

    Directory of Open Access Journals (Sweden)

    Karima Azdad

    Full Text Available The striatum is the major input structure of basal ganglia and is involved in adaptive control of behaviour through the selection of relevant informations. Dopaminergic neurons that innervate striatum die in Parkinson disease, leading to inefficient adaptive behaviour. Neuronal activity of striatal medium spiny neurons (MSN is modulated by dopamine receptors. Although dopamine signalling had received substantial attention, consequences of dopamine depletion on MSN intrinsic excitability remain unclear. Here we show, by performing perforated patch clamp recordings on brain slices, that dopamine depletion leads to an increase in MSN intrinsic excitability through the decrease of an inactivating A-type potassium current, I(A. Despite the large decrease in their excitatory synaptic inputs determined by the decreased dendritic spines density and the increase in minimal current to evoke the first EPSP, this increase in intrinsic excitability resulted in an enhanced responsiveness to their remaining synapses, allowing them to fire similarly or more efficiently following input stimulation than in control condition. Therefore, this increase in intrinsic excitability through the regulation of I(A represents a form of homeostatic plasticity allowing neurons to compensate for perturbations in synaptic transmission and to promote stability in firing. The present observations show that this homeostatic ability to maintain firing rates within functional range also occurs in pathological conditions, allowing stabilizing neural computation within affected neuronal networks.

  18. Interaural level difference-dependent gain control and synaptic scaling underlying binaural computation.

    Science.gov (United States)

    Xiong, Xiaorui R; Liang, Feixue; Li, Haifu; Mesik, Lukas; Zhang, Ke K; Polley, Daniel B; Tao, Huizhong W; Xiao, Zhongju; Zhang, Li I

    2013-08-21

    Binaural integration in the central nucleus of inferior colliculus (ICC) plays a critical role in sound localization. However, its arithmetic nature and underlying synaptic mechanisms remain unclear. Here, we showed in mouse ICC neurons that the contralateral dominance is created by a "push-pull"-like mechanism, with contralaterally dominant excitation and more bilaterally balanced inhibition. Importantly, binaural spiking response is generated apparently from an ipsilaterally mediated scaling of contralateral response, leaving frequency tuning unchanged. This scaling effect is attributed to a divisive attenuation of contralaterally evoked synaptic excitation onto ICC neurons with their inhibition largely unaffected. Thus, a gain control mediates the linear transformation from monaural to binaural spike responses. The gain value is modulated by interaural level difference (ILD) primarily through scaling excitation to different levels. The ILD-dependent synaptic scaling and gain adjustment allow ICC neurons to dynamically encode interaural sound localization cues while maintaining an invariant representation of other independent sound attributes. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Voluntary Fasting to Control Post-Ramadan Weight Gain among Overweight and Obese Women

    Directory of Open Access Journals (Sweden)

    Suriani Ismail

    2015-01-01

    Full Text Available Objectives: This study aimed to examine the effectiveness of an Islamic voluntary fasting intervention to control post-Ramadan weight gain. Methods: This study was conducted between July and November 2011. Two weight loss intervention programmes were developed and implemented among groups of overweight or obese Malay women living in the Malaysian cities of Putrajaya and Seremban: a standard programme promoting control of food intake according to national dietary guidelines (group B and a faith-based programme promoting voluntary fasting in addition to the standard programme (group A. Participants’ dietary practices (i.e., voluntary fasting practices, frequency of fruit/vegetable consumption per week and quantity of carbohydrates/protein consumed per day, body mass index (BMI, blood pressure, fasting blood high-density lipoprotein cholesterol (HDL-C and total cholesterol (TC:HDL-C ratio were assessed before Ramadan and three months post-Ramadan. Results: Voluntary fasting practices increased only in group A (P <0.01. Additionally, the quantity of protein/carbohydrates consumed per day, mean diastolic pressure and TC:HDL-C ratio decreased only in group A (P <0.01, 0.05, 0.02 and <0.01, respectively. Frequency of fruit/vegetable consumption per week, as well as HDL-C levels, increased only in group A (P = 0.03 and <0.01, respectively. Although changes in BMI between the groups was not significant (P = 0.08, BMI decrease among participants in group A was significant (P <0.01. Conclusion: Control of post-Ramadan weight gain was more evident in the faith-based intervention group. Healthcare providers should consider faith-based interventions to encourage weight loss during Ramadan and to prevent post-Ramadan weight gain among patients.

  20. Intelligent Control of Diesel Generators Using Gain-Scheduling Based on Online External-Load Estimation

    DEFF Research Database (Denmark)

    Mai, Christian; Jepsen, Kasper Lund; Yang, Zhenyu;

    2014-01-01

    keep a consistent performance for a wide range of operating conditions. Technically, a general nonlinear dynamic model is firstly developed based on fundamental principles of diesel generators. Then, the system parameters of this model can be identified experimentally or partially retrieved from...... the data-sheet for a specific unit. By combining an online external-load estimation with this specific units model, finally an intelligent control using the online gain scheduling strategy is proposed. The proposed solution is verified and analyzed based on a lab-sized emulator of a diesel generator, where...... a controlled AC-motor is employed to emulate a diesel engine. The testing results clearly show that the proposed control solution can lead to a better overall system performance than most existing solutions do, especially subject to widely diverse operating conditions....

  1. Gain tuning PI controllers for boiler turbine unit using a new hybrid jump PSO

    Directory of Open Access Journals (Sweden)

    Mohamed Sayed

    2015-05-01

    Full Text Available In this paper, a new hybrid jump PSO (HJPSO is proposed for tuning the gains of PI controllers to the boiler turbine unit. HJPSO based Gaussian and Cauchy mutation is proposed to improve the standard PSO performance. The new strategy is based on observing the local and global best particles which are not improved in a predefined number of iterations and moving these particles to a new best position. Besides, forming a new particle that handles the minimum error of each controller to replace the global best particle if it has best fitness. The simulation results show that the proposed algorithm has its ability in optimizing the control parameters and effectively achieved better performance when compared with other PSO algorithms.

  2. Stability of Gain Scheduling Control for Aircraft with Highly Nonlinear Behavior

    Directory of Open Access Journals (Sweden)

    Fany Mendez-Vergara

    2014-01-01

    Full Text Available The main goal of this work is to study the stability properties of an aircraft with nonlinear behavior, controlled using a gain scheduled approach. An output feedback is proposed which is able to guarantee asymptotical stability of the task-coordinates origin and safety of the operation in the entire flight envelope. The results are derived using theory of hybrid and singular perturbed systems. It is demonstrated that both body velocity and orientation asymptotic tracking can be obtained in spite of nonlinearities and uncertainty. The results are illustrated using numerical simulations in F16 jet.

  3. Social insect symbionts: evolution in homeostatic fortresses

    DEFF Research Database (Denmark)

    Hughes, David P; Pierce, Naomi E; Boomsma, Jacobus J

    2008-01-01

    The massive environmentally buffered nests of some social insects can contain millions of individuals and a wide variety of parasites, commensals and mutualists. We suggest that the ways in which these homeostatic fortress environments affect the evolution of social insect symbionts are relevant...... for epidemiology, evolutionary biology and macroecology. We contend that specialized parasites will tend to become less virulent and mutualists less cooperative, compared to those associated with solitary or small-colony hosts. These processes are expected to contribute to the very high symbiont diversity observed...

  4. Feedback shape control for deployable mesh reflectors using gain scheduling method

    Science.gov (United States)

    Xie, Yangmin; Shi, Hang; Alleyne, Andrew; Yang, Bingen

    2016-04-01

    This paper presents a theoretical study on the dynamic shape control problem of deployable mesh reflectors (DMRs) via feedback approaches. The reflector structure is simplified from a nonlinear model to be quasi-static with respect to temperature variations but dynamic with respect to mechanical vibrations. The orbital cycle is segmented into multiple temperature zones, and an H∞ robust state feedback controller is designed for each zone to guarantee the local stability of the system under the model uncertainty caused by thermal effects and to reject external force disturbances. At the same time, gain scheduling control method is adopted to compensate thermal distortions and to ensure smooth transition response when switching among the local robust controllers. A DMR model is considered in the case study to show the effectiveness of the control approach. The structural vibrations caused by external force disturbances can be sufficiently suppressed in a much shorter time. The closed loop response of the DMR structure shows that much higher surface accuracy is obtained during the orbiting mission compared to the open-loop configuration, and transient focal length and transient de-focus of the reflector are well controlled within the satisfactory bounds, demonstrating the numerical feasibility of the proposed method to solve the dynamic shape control problem of DMRs.

  5. Coherence-controlled transparency and far-from-degenerate parametric gain in a strongly-absorbing Doppler-broadened medium

    CERN Document Server

    George, T F; George, Thomas F.

    2000-01-01

    An inversionless gain of anti-Stokes radiation above the oscillation threshold in an optically-dense far-from-degenerate double-Lambda Doppler-broadened medium accompanied by Stokes gain is predicted. The outcomes are illustrated with numerical simulations applied to sodium dimer vapor. Optical switching from absorption to gain via transparency controlled by a small variation of the medium and of the driving radiation parameters which are at a level less than one photon per molecule is shown.

  6. Reward value-based gain control: divisive normalization in parietal cortex.

    Science.gov (United States)

    Louie, Kenway; Grattan, Lauren E; Glimcher, Paul W

    2011-07-20

    The representation of value is a critical component of decision making. Rational choice theory assumes that options are assigned absolute values, independent of the value or existence of other alternatives. However, context-dependent choice behavior in both animals and humans violates this assumption, suggesting that biological decision processes rely on comparative evaluation. Here we show that neurons in the monkey lateral intraparietal cortex encode a relative form of saccadic value, explicitly dependent on the values of the other available alternatives. Analogous to extra-classical receptive field effects in visual cortex, this relative representation incorporates target values outside the response field and is observed in both stimulus-driven activity and baseline firing rates. This context-dependent modulation is precisely described by divisive normalization, indicating that this standard form of sensory gain control may be a general mechanism of cortical computation. Such normalization in decision circuits effectively implements an adaptive gain control for value coding and provides a possible mechanistic basis for behavioral context-dependent violations of rationality.

  7. Analysis of sensorless control of brushless DC motor using unknown input observer with different gains

    Science.gov (United States)

    Astik, Mitesh B.; Bhatt, Praghnesh; Bhalja, Bhavesh R.

    2017-03-01

    A sensorless control scheme based on an unknown input observer is presented in this paper in which back EMF of the Brushless DC Motor (BLDC) is continuously estimated from available line voltages and currents. During negative rotation of motor, actual and estimated speed fail to track the reference speed and if the corrective action is not taken by the observer, the motor goes into saturation. To overcome this problem, the speed estimation algorithm has been implemented in this paper to control the dynamic behavior of the motor during negative rotation. The Ackermans method was used to calculate the gains of an unknown input observer which is based on the appropriate choice of the eigenvalues in advance. The criteria to choose eigenvalue is to obtain a balance between faster convergence rate and the least noise level. Simulations have been carried out for different disturbances such as step changes in motor reference speed and load torque. The comparative simulation results clearly depict that the disturbance effects in actual and estimated responses minimizes as observer gain setting increases.

  8. Design of a multivariable RF control system using gain-shaping in the frequency domain

    Science.gov (United States)

    Ziomek, C. D.; Jachim, S. P.; Natter, E. F.

    1991-05-01

    Due to the time-varying nature of the radio-frequency (RF) accelerator, RF field amplitude and phase parameters must be precisely controlled in order to confine and accelerate the charged particle beam. Typically, a feedback control system regulates the RF field, rejects noise and disturbances, and maintains operational stability over changes in the electrical structure of the accelerator. This paper describes a multivariable control system that compensates the electrical structure of the accelerator by using gain-shaping in the frequency domain. The amplitude and phase quantities have been resolved into in-phase and quadrature (I and Q) variables. These orthogonal variables have simple mathematical relationships, and can be analyzed using linear transfer function matrices. The transfer matrix theory has been applied to the design of the multivariable control system that regulates the RF field in-phase and quadrature components. Frequency-domain controllers compensate these two signals to provide desired frequency response characteristics. A control predistorter performs an inverse coupling function, so that the I and Q components are effectively decoupled by the accelerator. Furthermore, computer interface circuitry allows the adaptive optimization of the mathematical transfer functions of the compensators.

  9. Sliding mode controller gain adaptation and chattering reduction techniques for DSP-based PM DC motor drives

    DEFF Research Database (Denmark)

    Dal, Mehmet; Teodorescu, Remus

    2011-01-01

    In order to achieve and maintain the prospective benefits of sliding mode control (SMC) methodology, the phenomenon known as “chattering”, the main obstacle encountered in real-time applications, has to be suppressed. In this study, two promising switching control gain adaptation and chattering...... in order to find the best solution for chattering reduction. To find a practical solution a tunable low-pass filter (LPF) was used to average the discontinuous control term. The validity of the existing conditions for the gain adaptation methods are examined and observer gain value was determined through...

  10. Maximum Power Point Tracking Controller for Thermoelectric Generators with Peak Gain Control of Boost DC-DC Converters

    Science.gov (United States)

    Park, Jungyong; Kim, Shiho

    2012-06-01

    An analog maximum power point tracking (MPPT) circuit for a thermoelectric generator (TEG) is proposed. We show that the peak point of the voltage conversion gain of a boost DC-DC converter with an input voltage source having an internal resistor is the maximum power point of the TEG. The key characteristic of the proposed MPPT controller is that the duty ratio of the input clock pulse to the boost DC-DC converter shifts toward the maximum power point of the TEG by seeking the peak gain point of the boost DC-DC converters. The proposed MPPT technique provides a simple and useful analog MPPT solution, without employing digital microcontroller units.

  11. Single-beam water vapor detection system with automatic photoelectric conversion gain control

    Science.gov (United States)

    Zhu, C. G.; Chang, J.; Wang, P. P.; Wang, Q.; Wei, W.; Liu, Z.; Zhang, S. S.

    2014-11-01

    A single-beam optical sensor system with automatic photoelectric conversion gain control is proposed for doing high reliability water vapor detection under relatively rough environmental conditions. Comparing to a dual-beam system, it can distinguish the finer photocurrent variations caused by the optical power drift and provide timely compensation by automatically adjusting the photoelectric conversion gain. This system can be rarely affected by the optical power drift caused by fluctuating ambient temperature or variation of fiber bending loss. The deviation of the single-beam system is below 1.11% when photocurrent decays due to fiber bending loss for bending radius of 5 mm, which is obviously lower than the dual-beam system (8.82%). We also demonstrate the long-term stability of the single-beam system by monitoring a 660 ppm by volume (ppmv) water vapor sample continuously for 24 h. The maximum deviation of the measured concentration during the whole testing period does not exceed 10 ppmv. Experiments have shown that the new system features better reliability and is more apt for remote sensing application which is often subject to light transmission loss.

  12. [Open loop gain of the CO2-ventilation feedback control system in chronic obstructive pulmonary disease].

    Science.gov (United States)

    Kimura, H; Kunitomo, F; Okita, S; Tojima, H; Tatsumi, K; Kuriyama, T; Hashizume, I; Honda, Y

    1989-07-01

    To evaluate the stability of the CO2-ventilation feedback system, we measured its open loop gain (G) in 12 patients with chronic obstructive pulmonary disease (COPD) and 15 control subjects. Then, we compared G to the conventional slope of the CO2-ventilation response line (S) and that of the metabolic hyperbola (SL). G was determined as the ratio of S to SL by applying external dead space of 250 and 500 ml. G, S and 1/SL in the control and the COPD were +17.1 +/- 7.2 (Mean +/- SD), 1.70 +/- 0.75 L.min-1.Torr-1 and -10.4 +/- 2.0 L-1.min.Torr, and -7.2 +/- 3.3, 0.48 +/- 0.27 L.min-1.Torr-1 and -16.1 +/- 6.4 L-1.min.Torr, respectively. G was significantly correlated with S in both groups, but that was not the case in 1/SL. The magnitude of G and S in COPD was about 42% and 28% of the control, indicating that G was maintained more stable than S. These data suggest that the decreased G in the COPD resulted from insufficient compensation of ventilatory drive, whereas 1/SL increased higher than the control. We conclude that G can be used to indicate the stability of the CO2-ventilation feedback system better than S.

  13. A wideband LC-VCO with small VCO gain variation and adaptive power control

    Institute of Scientific and Technical Information of China (English)

    Li Bin; Fan Xiangning; Wang Zhigong

    2012-01-01

    A wideband LC tank voltage-controlled-oscillator (VCO) is proposed.To solve the impacts ofwideband operation on VCO gain (Kvco) variation and start-up constraint,a binary-weighted varactor array and a binary-weighted negative resistance array all with optimal unit values are designed.Implemented in a 0.18 μm CMOS process,the proposed VCO shows a frequency tuning range from 1.9 to 3.1 GHz,with a current consumption varying accordingly from 14.2 to 4 mA from a 1.8 V supply.With the proposed Kvco suppression technique,the Kvco varies from 50 to 60 MHz/V in the entire frequency range.The measured phase noise is -117 dBc/Hz at a 1 MHz offset from a 3 GHz carrier.

  14. CLOSED LOOP CONTROL OF THREE PORT CONVERTER WITH HIGH VOLTAGE GAIN

    Directory of Open Access Journals (Sweden)

    Santhi Mary Antony A

    2015-08-01

    Full Text Available Photovoltaic (PV system is one of the best renewable energy sources for power generation system due to their pollution free and low cost properties. The PV cells has less efficiency compared to other source of power generation. The system efficiency is improved by reducing components count, which reduces the losses. In this paper a new three port converter (TPC is proposed for stand-alone renewable power applications. The proposed converter has three switches to achieve the power flow control. Single inductor is used for common energy transfer element for two different sources. The coupled inductor is used to increase the voltage conversion ratio with reasonable duty cycle. Thus the proposed converter has high voltage gain with less components count. The output voltage is regulated through feedback network. The system performance is verified through simulation results.

  15. Homeostatic fluctuations of a tissue surface

    CERN Document Server

    Risler, Thomas; Prost, Jacques

    2015-01-01

    We study the surface fluctuations of a tissue with a dynamics dictated by cell-rearrangement, cell-division and cell-death processes. Surface fluctuations are calculated in the homeostatic state, where cell division and cell death equilibrate on average. The obtained fluctuation spectrum can be mapped onto several other spectra such as those characterizing incompressible fluids, compressible Maxwell elastomers or permeable membranes in appropriate asymptotic regimes. Since cell division and cell death are out-of-equilibrium processes, detailed balance is broken, but a generalized fluctuation-response relation is satisfied in terms of appropriate observables. Our work is a first step toward the description of the out-of-equilibrium fluctuations of the surface of a thick epithelium and its dynamical response to external perturbations.

  16. Automatic Gain Control in Mass Spectrometry using a Jet Disrupter Electrode in an Electrodynamic Ion Funnel

    Energy Technology Data Exchange (ETDEWEB)

    Page, Jason S.; Bogdanov, Bogdan; Vilkov, Andrey N.; Prior, David C.; Buschbach, Michael A.; Tang, Keqi; Smith, Richard D.

    2005-02-01

    We report on the use of a jet disrupter electrode in an electrodynamic ion funnel as an electronic valve to regulate the intensity of the ion beam transmitted through the interface of a mass spectrometer in order to perform automatic gain control (AGC). The ion flux is determined by either directly detecting the ion current on the conductance limiting orifice of the ion funnel or using a short mass spectrometry acquisition. Based upon the ion flux intensity, the voltage of the jet disrupter is adjusted to alter the transmission efficiency of the ion funnel to provide a desired ion population to the mass analyzer. Ion beam regulation by an ion funnel is shown to provide an unbiased control to within a few percent of a targeted ion intensity or abundance. The utility of ion funnel AGC was evaluated using a protein tryptic digest analyzed with liquid chromatography Fourier transform ion cyclotron resonance (LC-FTICR) mass spectrometry. The ion population in the ICR cell was accurately controlled to a variety of different levels, which improved data quality and provided better mass measurement accuracy.

  17. Homeostatic-like plasticity of the primary motor hand area is impaired in focal hand dystonia.

    Science.gov (United States)

    Quartarone, Angelo; Rizzo, Vincenzo; Bagnato, Sergio; Morgante, Francesca; Sant'Angelo, Antonino; Romano, Marcello; Crupi, Domenica; Girlanda, Paolo; Rothwell, John C; Siebner, Hartwig R

    2005-08-01

    The excitability of inhibitory circuits in patients with writer's cramp is reduced at multiple levels within the sensorimotor system, including the primary motor hand area (M1). Although this may play a major role in the pathophysiology of writer's cramp, it is still unclear what factors may cause the imbalance between inhibition and excitation to arise. One possibility is that homeostatic mechanisms that keep cortical excitability within a normal physiological range are impaired. In eight patients with writer's cramp and eight healthy age-matched controls, we combined low-frequency repetitive transcranial magnetic stimulation (rTMS) with transcranial direct current stimulation (TDCS) to probe regional homeostatic plasticity of the left M1. Confirming our previous study (Siebner et al., J Neurosci 2004; 24: 3379-85), 'facilitatory' preconditioning of the M1 with anodal TDCS enhanced the inhibitory effect of subsequent 1 Hz rTMS on corticospinal excitability. Conversely, 'inhibitory' preconditioning with cathodal TDCS reversed the after effect of 1 Hz rTMS, producing an increase in corticospinal excitability. The results were quite different in patients with writer's cramp. Following preconditioning with TDCS, 1 Hz rTMS induced no consistent changes in corticospinal excitability, indicating a loss of the normal 'homeostatic' response pattern. In addition, the normal inhibitory effect of preconditioning with cathodal TDCS was absent. The present data suggest that homeostatic mechanisms that stabilize excitability levels within a useful dynamic range are impaired in patients with writer's cramp. We propose that a faulty homeostatic response to acute increases in corticospinal excitability favours maladaptive motor plasticity. The role of homeostatic-like plasticity in the pathophysiology of task-specific dystonias warrants further study.

  18. Homeostasis balance, homeostasis imbalance or distinct motivational processes? Comments on Marks (2015 ‘Homeostatic Theory of Obesity’

    Directory of Open Access Journals (Sweden)

    Luc G Pelletier

    2016-01-01

    Full Text Available In his article, ‘Homeostatic theory of obesity’, Marks suggested that imbalances in homeostatic processes could explain weight gain and obesity. He proposes that over-consumption of high-caloric, low-nutrient and low satiating foods, combined with a stressful environment, is the origin of weight gain. Once weight gain occurs, individuals may develop body dissatisfaction and negative affect, leading to continued over-consumption, which sets in motion a system of feedback loops that leads to a Circle of Discontent and further weight gain. In this article, we attempt to clarify certain problematic aspects of Marks framework and identify specific directions that researchers should pursue to address these shortcomings.

  19. Design and performance of an Automatic Gain Control system for the High Energy X-Ray Timing Experiment

    Science.gov (United States)

    Pelling, Michael R.; Rothschild, Richard E.; Macdonald, Daniel R.; Hertel, Robert; Nishiie, Edward

    1991-01-01

    The High Energy X-Ray Timing Experiment (HEXTE), currently under development for the X-Ray Timing Explorer (XTE) mission, employs a closed loop gain control system to attain 0.5 percent stabilization of each of eight-phoswich detector gains. This Automatic Gain Control (AGC) system utilizes a split window discriminator scheme to control the response of each detector pulse height analyzer to gated Am-241 X-ray events at 60 keV. A prototype AGC system has been implemented and tested within the gain perturbation environment expected to be experienced by the HEXTE instrument in flight. The AGC system and test configuration are described. Response, stability and noise characteristics are measured and compared with theoretical predictions. The system is found to be generally suitable for the HEXTE application.

  20. Design and performance of an Automatic Gain Control system for the High Energy X-Ray Timing Experiment

    Science.gov (United States)

    Pelling, Michael R.; Rothschild, Richard E.; Macdonald, Daniel R.; Hertel, Robert; Nishiie, Edward

    1991-01-01

    The High Energy X-Ray Timing Experiment (HEXTE), currently under development for the X-Ray Timing Explorer (XTE) mission, employs a closed loop gain control system to attain 0.5 percent stabilization of each of eight-phoswich detector gains. This Automatic Gain Control (AGC) system utilizes a split window discriminator scheme to control the response of each detector pulse height analyzer to gated Am-241 X-ray events at 60 keV. A prototype AGC system has been implemented and tested within the gain perturbation environment expected to be experienced by the HEXTE instrument in flight. The AGC system and test configuration are described. Response, stability and noise characteristics are measured and compared with theoretical predictions. The system is found to be generally suitable for the HEXTE application.

  1. Controllable optical response by modifying the gain and loss of a mechanical resonator and cavity mode in an optomechanical system

    CERN Document Server

    Liu, Yu-Long; Zhang, Jing; Özdemir, Şahin Kaya; Yang, Lan; Nori, Franco; Liu, Yu-xi

    2016-01-01

    We theoretically study a strongly-driven optomechanical system which consists of a passive optical cavity and an active mechanical resonator. When the optomechanical coupling strength is varied, phase transitions, which are similar those observed in $\\mathcal{PT}$-symmetric systems, are observed. We show that the optical transmission can be controlled by changing the gain of the mechanical resonator and loss of the optical cavity mode. Especially, we find that: (i) for balanced gain and loss, optical amplification and absorption can be tuned by changing the optomechanical coupling strength through a control field; (ii) for unbalanced gain and loss, even with a tiny mechanical gain, both optomechanically-induced transparency and anomalous dispersion can be observed around a critical point, which exhibits an ultra-long group delay. The time delay $\\tau$ can be optimized by regulating the optomechanical coupling strength through the control field and improved up to several orders of magnitude ($\\tau\\sim2$ $\\math...

  2. Homeostatic imbalance between apoptosis and cell renewal in the liver of premature aging Xpd mice.

    Science.gov (United States)

    Park, Jung Yoon; Cho, Mi-Ook; Leonard, Shanique; Calder, Brent; Mian, I Saira; Kim, Woo Ho; Wijnhoven, Susan; van Steeg, Harry; Mitchell, James; van der Horst, Gijsbertus T J; Hoeijmakers, Jan; Cohen, Pinchas; Vijg, Jan; Suh, Yousin

    2008-06-11

    Unrepaired or misrepaired DNA damage has been implicated as a causal factor in cancer and aging. Xpd(TTD) mice, harboring defects in nucleotide excision repair and transcription due to a mutation in the Xpd gene (R722W), display severe symptoms of premature aging but have a reduced incidence of cancer. To gain further insight into the molecular basis of the mutant-specific manifestation of age-related phenotypes, we used comparative microarray analysis of young and old female livers to discover gene expression signatures distinguishing Xpd(TTD) mice from their age-matched wild type controls. We found a transcription signature of increased apoptosis in the Xpd(TTD) mice, which was confirmed by in situ immunohistochemical analysis and found to be accompanied by increased proliferation. However, apoptosis rate exceeded the rate of proliferation, resulting in homeostatic imbalance. Interestingly, a metabolic response signature was observed involving decreased energy metabolism and reduced IGF-1 signaling, a major modulator of life span. We conclude that while the increased apoptotic response to endogenous DNA damage contributes to the accelerated aging phenotypes and the reduced cancer incidence observed in the Xpd(TTD) mice, the signature of reduced energy metabolism is likely to reflect a compensatory adjustment to limit the increased genotoxic stress in these mutants. These results support a general model for premature aging in DNA repair deficient mice based on cellular responses to DNA damage that impair normal tissue homeostasis.

  3. Homeostatic imbalance between apoptosis and cell renewal in the liver of premature aging Xpd mice.

    Directory of Open Access Journals (Sweden)

    Jung Yoon Park

    Full Text Available Unrepaired or misrepaired DNA damage has been implicated as a causal factor in cancer and aging. Xpd(TTD mice, harboring defects in nucleotide excision repair and transcription due to a mutation in the Xpd gene (R722W, display severe symptoms of premature aging but have a reduced incidence of cancer. To gain further insight into the molecular basis of the mutant-specific manifestation of age-related phenotypes, we used comparative microarray analysis of young and old female livers to discover gene expression signatures distinguishing Xpd(TTD mice from their age-matched wild type controls. We found a transcription signature of increased apoptosis in the Xpd(TTD mice, which was confirmed by in situ immunohistochemical analysis and found to be accompanied by increased proliferation. However, apoptosis rate exceeded the rate of proliferation, resulting in homeostatic imbalance. Interestingly, a metabolic response signature was observed involving decreased energy metabolism and reduced IGF-1 signaling, a major modulator of life span. We conclude that while the increased apoptotic response to endogenous DNA damage contributes to the accelerated aging phenotypes and the reduced cancer incidence observed in the Xpd(TTD mice, the signature of reduced energy metabolism is likely to reflect a compensatory adjustment to limit the increased genotoxic stress in these mutants. These results support a general model for premature aging in DNA repair deficient mice based on cellular responses to DNA damage that impair normal tissue homeostasis.

  4. Bio-responsive polymer hydrogels homeostatically regulate blood coagulation

    Science.gov (United States)

    Maitz, Manfred F.; Freudenberg, Uwe; Tsurkan, Mikhail V.; Fischer, Marion; Beyrich, Theresa; Werner, Carsten

    2013-01-01

    Bio-responsive polymer architectures can empower medical therapies by engaging molecular feedback-response mechanisms resembling the homeostatic adaptation of living tissues to varying environmental constraints. Here we show that a blood coagulation-responsive hydrogel system can deliver heparin in amounts triggered by the environmental levels of thrombin, the key enzyme of the coagulation cascade, which—in turn—becomes inactivated due to released heparin. The bio-responsive hydrogel quantitatively quenches blood coagulation over several hours in the presence of pro-coagulant stimuli and during repeated incubation with fresh, non-anticoagulated blood. These features enable the introduced material to provide sustainable, autoregulated anticoagulation, addressing a key challenge of many medical therapies. Beyond that, the explored concept may facilitate the development of materials that allow the effective and controlled application of drugs and biomolecules. PMID:23868446

  5. Propagation of Homeostatic Sleep Signals by Segregated Synaptic Microcircuits of the Drosophila Mushroom Body.

    Science.gov (United States)

    Sitaraman, Divya; Aso, Yoshinori; Jin, Xin; Chen, Nan; Felix, Mario; Rubin, Gerald M; Nitabach, Michael N

    2015-11-16

    The Drosophila mushroom body (MB) is a key associative memory center that has also been implicated in the control of sleep. However, the identity of MB neurons underlying homeostatic sleep regulation, as well as the types of sleep signals generated by specific classes of MB neurons, has remained poorly understood. We recently identified two MB output neuron (MBON) classes whose axons convey sleep control signals from the MB to converge in the same downstream target region: a cholinergic sleep-promoting MBON class and a glutamatergic wake-promoting MBON class. Here, we deploy a combination of neurogenetic, behavioral, and physiological approaches to identify and mechanistically dissect sleep-controlling circuits of the MB. Our studies reveal the existence of two segregated excitatory synaptic microcircuits that propagate homeostatic sleep information from different populations of intrinsic MB "Kenyon cells" (KCs) to specific sleep-regulating MBONs: sleep-promoting KCs increase sleep by preferentially activating the cholinergic MBONs, while wake-promoting KCs decrease sleep by preferentially activating the glutamatergic MBONs. Importantly, activity of the sleep-promoting MB microcircuit is increased by sleep deprivation and is necessary for homeostatic rebound sleep (i.e., the increased sleep that occurs after, and in compensation for, sleep lost during deprivation). These studies reveal for the first time specific functional connections between subsets of KCs and particular MBONs and establish the identity of synaptic microcircuits underlying transmission of homeostatic sleep signals in the MB.

  6. Homeostatic plasticity: single hippocampal neurons see the light.

    Science.gov (United States)

    Sutton, Michael A

    2010-11-04

    Neurons adapt to altered network activity through homeostatic changes in synaptic function. In this issue of Neuron, Goold and Nicoll report that chronic hyperactivation of individual CA1 pyramidal neurons drives cell-autonomous, compensatory synapse elimination via CaMKIV-dependent transcription. These findings suggest that neurons gauge their intrinsic activity to instruct homeostatic regulation of synaptic inputs.

  7. Sulfur dioxide control by electric utilities: What are the gains from trade?

    Science.gov (United States)

    Carlson, Curtis Paul

    1999-11-01

    Title IV of the 1990 Clean Air Act Amendments (CAAA) established a market for transferable sulfur dioxide (SO2) emission allowances among electric utilities. This market offers firms facing high marginal pollution abatement costs the opportunity to purchase the tight to emit SO2 from firms with lower costs; as such, it is expected to yield cost savings compared to a command-and-control approach to environmental regulation. This thesis uses econometrically estimated marginal abatement cost functions for power plants affected by Title IV of the CAAA to evaluate the performance of the SO2 allowance market. Specifically, I investigate whether the much-heralded fall in the cost of abating SO2, compared to original estimates, can be attributed to allowance trading. I demonstrate that, for plants that use low-sulfur coal to reduce SO2 emissions, technical change and the fall in low sulfur coal prices have lowered marginal abatement cost curves by over 50% since 1985. This is the main source of cost reductions rather than trading per se. In the long run, allowance trading may achieve cost savings of 700-800 million per year compared to an "enlightened" command and control program characterized by a uniform emission rate standard. However, a comparison of potential cost savings in 1995 and 1996 with actual emissions costs suggest that most trading gains were unrealized in the first two years of the program.

  8. Controlling the dynamical behavior of nonlinear fiber ring resonators with balanced loss and gain

    CERN Document Server

    Deka, Jyoti P; Sarma, Amarendra K

    2015-01-01

    We show the possibility of controlling the dynamical behavior of a single fiber ring (SFR) resonator system with the fiber being an amplified (gain) channel and the ring being attenuated (loss) nonlinear dielectric medium. The system considered here is a simple alteration in the basic building block of the parity time (PT) symmetric synthetic coupler structures reported in A. Regensburger et al., Nature 488, 167 (2012). We find that this result in a dynamically controllable algorithm for the chaotic dynamics inherent in the system. We have also shown the dependence of the period doubling point upon the input amplitude, emphasizing on the dynamical aspects of our system. Moreover, the fact that the resonator essentially plays the role of a damped harmonic oscillator has been elucidated with the non-zero intensity inside the resonator due to constant influx of input light. This study may be a step forward to further investigations in regard to the inter-connectivity between the PT symmetry and chaos along with ...

  9. Controlling the gain shape of Er3+-doped fluorozirconate fibre amplifier by a coherent field

    Institute of Scientific and Technical Information of China (English)

    张惠芳; 吴金辉; 高锦岳

    2003-01-01

    We proposed a four-level system to explore the quantum interference effects on optical amplification. We found that the gain of the probe, including positions and values of gain peaks, can be adjusted by changing the coherent field and the incoherent pumping. At the same time, we can also modify the absorption profile of electromagnetically induced transparency by the incoherent pump. The results provide a method to flatten the gain of Erbium-doped fibre amplifiers.

  10. A new adjustable gains for second order sliding mode control of saturated DFIG-based wind turbine

    Science.gov (United States)

    Bounadja, E.; Djahbar, A.; Taleb, R.; Boudjema, Z.

    2017-02-01

    The control of Doubly-Fed induction generator (DFIG), used in wind energy conversion, has been given a great deal of interest. Frequently, this control has been dealt with ignoring the magnetic saturation effect in the DFIG model. The aim of the present work is twofold: firstly, the magnetic saturation effect is accounted in the control design model; secondly, a new second order sliding mode control scheme using adjustable-gains (AG-SOSMC) is proposed to control the DFIG via its rotor side converter. This scheme allows the independent control of the generated active and reactive power. Conventionally, the second order sliding mode control (SOSMC) applied to the DFIG, utilize the super-twisting algorithm with fixed gains. In the proposed AG-SOSMC, a simple means by which the controller can adjust its behavior is used. For that, a linear function is used to represent the variation in gain as a function of the absolute value of the discrepancy between the reference rotor current and its measured value. The transient DFIG speed response using the aforementioned characteristic is compared with the one determined by using the conventional SOSMC controller with fixed gains. Simulation results show, accurate dynamic performances, quicker transient response and more accurate control are achieved for different operating conditions.

  11. Homeostatic scaling of excitability in recurrent neural networks.

    Directory of Open Access Journals (Sweden)

    Michiel W H Remme

    Full Text Available Neurons adjust their intrinsic excitability when experiencing a persistent change in synaptic drive. This process can prevent neural activity from moving into either a quiescent state or a saturated state in the face of ongoing plasticity, and is thought to promote stability of the network in which neurons reside. However, most neurons are embedded in recurrent networks, which require a delicate balance between excitation and inhibition to maintain network stability. This balance could be disrupted when neurons independently adjust their intrinsic excitability. Here, we study the functioning of activity-dependent homeostatic scaling of intrinsic excitability (HSE in a recurrent neural network. Using both simulations of a recurrent network consisting of excitatory and inhibitory neurons that implement HSE, and a mean-field description of adapting excitatory and inhibitory populations, we show that the stability of such adapting networks critically depends on the relationship between the adaptation time scales of both neuron populations. In a stable adapting network, HSE can keep all neurons functioning within their dynamic range, while the network is undergoing several (pathophysiologically relevant types of plasticity, such as persistent changes in external drive, changes in connection strengths, or the loss of inhibitory cells from the network. However, HSE cannot prevent the unstable network dynamics that result when, due to such plasticity, recurrent excitation in the network becomes too strong compared to feedback inhibition. This suggests that keeping a neural network in a stable and functional state requires the coordination of distinct homeostatic mechanisms that operate not only by adjusting neural excitability, but also by controlling network connectivity.

  12. A digitally calibrated CMOS RMS power detector for RF automatic gain control

    Institute of Scientific and Technical Information of China (English)

    Yan Taotao; Wang Hui; Li Jinbo; Zhou Jianjun

    2013-01-01

    This paper presents the design and implementation of a digitally calibrated CMOS wideband radio frequency (RF) root-mean-square (RMS) power detector for high accuracy RF automatic gain control (AGC).The proposed RMS power detector demonstrates accurate power detection in the presence of process,supply voltage,and temperature (PVT) variations by employing a digital calibration scheme.It also consumes low power and occupies a small chip area.The measurement results show that the scheme improves the accuracy of the detector to better than 0.3 dB over the PVT variations and wide operating frequency range from 0.2 to 0.8 GHz.Implemented in a 0.18 μm CMOS process and occupying a small die area of 263 × 214 μm2,the proposed digitally calibrated CMOS RMS power detector only consumes 1.6 mA in power detection mode and 2.1 mA in digital calibration mode from a 1.8 V supply voltage.

  13. DFIG-Based Wind Turbine Robust Control Using High-Order Sliding Modes and a High Gain Observer

    OpenAIRE

    Beltran, Brice; Benbouzid, Mohamed; Ahmed-Ali, Tarek; Mangel, Hervé

    2011-01-01

    International audience; This paper deals with the power generation control in variable speed wind turbines. In this context, a control strategy is proposed to ensure power extraction optimization of a DFIG-based wind turbine. The proposed control strategy combines an MPPT using a high gain observer and second-order sliding mode for the DFIG control. This strategy presents attractive features such as chattering-free behavior, finite reaching time, robustness and unmodeled dynamics (generator a...

  14. Complement in the Homeostatic and Ischemic Brain

    Science.gov (United States)

    Alawieh, Ali; Elvington, Andrew; Tomlinson, Stephen

    2015-01-01

    The complement system is a component of the immune system involved in both recognition and response to pathogens, and it is implicated in an increasing number of homeostatic and disease processes. It is well documented that reperfusion of ischemic tissue results in complement activation and an inflammatory response that causes post-reperfusion injury. This occurs following cerebral ischemia and reperfusion and triggers secondary damage that extends beyond the initial infarcted area, an outcome that has rationalized the use of complement inhibitors as candidate therapeutics after stroke. In the central nervous system, however, recent studies have revealed that complement also has essential roles in synaptic pruning, neurogenesis, and neuronal migration. In the context of recovery after stroke, these apparent divergent functions of complement may account for findings that the protective effect of complement inhibition in the acute phase after stroke is not always maintained in the subacute and chronic phases. The development of effective stroke therapies based on modulation of the complement system will require a detailed understanding of complement-dependent processes in both early neurodegenerative events and delayed neuro-reparatory processes. Here, we review the role of complement in normal brain physiology, the events initiating complement activation after cerebral ischemia-reperfusion injury, and the contribution of complement to both injury and recovery. We also discuss how the design of future experiments may better characterize the dual role of complement in recovery after ischemic stroke. PMID:26322048

  15. Lasing oscillation condition and group delay control in gain-assisted plasmon-induced transparency

    CERN Document Server

    Deng, Zi-Lan; Wang, He-Zhou; Cheng, S H; Li, Jensen

    2012-01-01

    A gain-assisted plasmonic waveguide with two detuned resonators is investigated in the plasmon-induced transparency window. Phase map is employed to study power transmittance and group delay for varying gain coefficients and frequency detunings of the two resonators. The gain coefficient for lasing oscillation condition is analytically shown to vary quadratically with the frequency detuning. In the amplification regime below the lasing threshold, the spectrum implies not only large group delay, but also high transmittance and narrow linewidth. This is in contrast to those in the loss-compensation regime and the passive case in which there always exists a trade-off between the linewidth and the peak transmittance.

  16. Controllable optical response by modifying the gain and loss of a mechanical resonator and cavity mode in an optomechanical system

    Science.gov (United States)

    Liu, Yu-Long; Wu, Rebing; Zhang, Jing; Özdemir, Şahin Kaya; Yang, Lan; Nori, Franco; Liu, Yu-xi

    2017-01-01

    We theoretically study a strongly driven optomechanical system which consists of a passive optical cavity and an active mechanical resonator. When the optomechanical coupling strength is varied, phase transitions, which are similar to those observed in PT -symmetric systems, are observed. We show that the optical transmission can be controlled by changing the gain of the mechanical resonator and loss of the optical cavity mode. Especially, we find that (i) for balanced gain and loss, optical amplification and absorption can be tuned by changing the optomechanical coupling strength through a control field; (ii) for unbalanced gain and loss, even with a tiny mechanical gain, both optomechanically induced transparency and anomalous dispersion can be observed around a critical point, which exhibits an ultralong group delay. The time delay τ can be optimized by regulating the optomechanical coupling strength through the control field, and it can be improved up to several orders of magnitude (τ ˜2 ms ) compared to that of conventional optomechanical systems (τ ˜1 μ s ). The presence of mechanical gain makes the group delay more robust to environmental perturbations. Our proposal provides a powerful platform to control light transport using a PT -symmetric-like optomechanical system.

  17. Dynamic Sliding Mode Evolution PWM Controller for a Novel High-Gain Interleaved DC-DC Converter in PV System

    Directory of Open Access Journals (Sweden)

    Taizhou Bei

    2014-01-01

    Full Text Available Considering the disadvantages of the traditional high-gain DC-DC converter such as big size, high voltage stress of switches, and large input current ripple, a novel high-gain interleaved boost converter with coupled-inductor and switched-capacitor was proposed correspondingly and the operation principle together with the steady-state analysis of this converter was also described. Besides, a new control approach-dynamic sliding mode evolution PWM controller (DSME PWM for the novel topological converter based on both dynamic evolution and sliding mode control was also presented. From the simulation results and experimental validation the proposed converter can fulfill high-gain boost, low ripple of both the input current and the output voltage. Furthermore, MPPT technique can be also achieved in a short time by simulation. The efficiency and stability of the converter proposed in this paper can be improved.

  18. Exercise Training and Weight Gain in Obese Pregnant Women: A Randomized Controlled Trial (ETIP Trial.

    Directory of Open Access Journals (Sweden)

    Kirsti Krohn Garnæs

    2016-07-01

    Full Text Available The effectiveness of exercise training for preventing excessive gestational weight gain (GWG and gestational diabetes mellitus (GDM is still uncertain. As maternal obesity is associated with both GWG and GDM, there is a special need to assess whether prenatal exercise training programs provided to obese women reduce the risk of adverse pregnancy outcomes. Our primary aim was to assess whether regular supervised exercise training in pregnancy could reduce GWG in women with prepregnancy overweight/obesity. Secondary aims were to examine the effects of exercise in pregnancy on 30 outcomes including GDM incidence, blood pressure, blood measurements, skinfold thickness, and body composition.This was a single-center study where we randomized (1:1 91 pregnant women with a prepregnancy body mass index (BMI ≥ 28 kg/m2 to exercise training (n = 46 or control (standard maternity care (n = 45. Assessments were done at baseline (pregnancy week 12-18 and in late pregnancy (week 34-37, as well as at delivery. The exercise group was offered thrice weekly supervised sessions of 35 min of moderate intensity endurance exercise and 25 min of strength training. Seventeen women were lost to follow-up (eight in the exercise group and nine in the control group. Our primary endpoint was GWG from baseline testing to delivery. The principal analyses were done as intention-to-treat analyses, with supplementary per protocol analyses where we assessed outcomes in the women who adhered to the exercise program (n = 19 compared to the control group. Mean GWG from baseline to delivery was 10.5 kg in the exercise group and 9.2 kg in the control group, with a mean difference of 0.92 kg (95% CI -1.35, 3.18; p = 0.43. Among the 30 secondary outcomes in late pregnancy, an apparent reduction was recorded in the incidence of GDM (2009 WHO definition in the exercise group (2 cases; 6.1% compared to the control group (9 cases; 27.3%, with an odds ratio of 0.1 (95% CI 0.02, 0.95; p = 0

  19. Enhancement in the gain recovery of a semiconductor optical amplifier by device temperature control

    Indian Academy of Sciences (India)

    YOGESH KUMAR; M R SHENOY

    2016-12-01

    We present a numerical investigation on the temperature dependence of gain recovery, of a semiconductor optical amplifier (SOA). It is shown that the decrease in temperature significantly speed-up the gain recovery of the SOA. Under typical operating conditions, a 20 K reduction in temperature of the SOA results in a decrease of 150 ps in the gain recovery time. A comparative estimation of device temperature and assisted-light power requirements for enhancing the gain recovery has also been carried out. It is found that, a decrease of 8 K in the temperature of the SOA, is as effective in enhancing the gain recovery as injection of 25 dBm assistedlight power in the counter-propagating mode. Our study shows that under moderate current biasing conditions, temperature reduction is a better and convenient option to speed-up the gain recovery of an SOA, than the use of external assisted-light injection, which requires an additional laser source and wavelength division multiplexing(WDM) components for coupling and de-coupling, leading to insertion losses in the communication channel.

  20. Gain self-scheduled H∞ control for morphing aircraft in the wing transition process based on an LPV model

    Institute of Scientific and Technical Information of China (English)

    Yue Ting; Wang Lixin; Ai Junqiang

    2013-01-01

    This article investigates gain self-scheduled H∞ robust control system design for a tailless folding-wing morphing aircraft in the wing shape varying process.During the wing morphing phase,the aircraft's dynamic response will be governed by time-varying aerodynamic forces and moments.Nonlinear dynamic equations of the morphing aircraft are linearized by using Jacobian linearization approach,and a linear parameter varying (LPV) model of the morphing aircraft in wing folding is obtained.A multi-loop controller for the morphing aircraft is formulated to guarantee stability for the wing shape transition process.The proposed controller uses a set of inner-loop gains to provide stability using classical techniques,whereas a gain self-scheduled H∞ outer-loop controller is devised to guarantee a specific level of robust stability and performance for the time-varying dynamics.The closed-loop simulations show that speed and altitude vary slightly during the whole wing folding process,and they converge rapidly after the process ends.This proves that the gain self-scheduled H∞ robust controller can guarantee a satisfactory dynamic performance for the morphing aircraft during the whole wing shape transition process.Finally,the flight control system's robustness for the wing folding process is verified according to uncertainties of the aerodynamic parameters in the nonlinear model.

  1. Decision-directed automatic gain control for MAPSK systems. [M-ary Amplitude and Phase Shift Keying

    Science.gov (United States)

    Weber, W. J., III

    1974-01-01

    An automatic gain control (AGC) loop is presented for use with M-ary amplitude and phase shift keying (MAPSK) systems. The gain control amplifier is regulated by an error signal formed by the difference between the estimated amplitude level and the received amplitude level. The AGC performance is thus independent of the short-term average received signal energy. AGC loop analysis and simulation is presented for M-ary amplitude shift keying and quadrature amplitude shift keying. The AGC is shown to have a negligible degradation on the symbol probability of error for most practical cases. A generalized AGC for an arbitrary MAPSK system is presented.

  2. Effects of gain-scheduling methods in a classical wind turbine controller on wind turbine aeroservoelastic modes and loads

    DEFF Research Database (Denmark)

    Tibaldi, Carlo; Henriksen, Lars Christian; Hansen, Morten Hartvig

    2014-01-01

    The eects of dierent gain-scheduling methods for a classical wind turbine controller, operating in full load region, on the wind turbine aeroservoelastic modes and loads are investigated in this work. The dierent techniques are derived looking at the physical problem to take into account the chan......The eects of dierent gain-scheduling methods for a classical wind turbine controller, operating in full load region, on the wind turbine aeroservoelastic modes and loads are investigated in this work. The dierent techniques are derived looking at the physical problem to take into account...

  3. Improvement of Hydraulic Edge Position Control System by Proportion Sliding Mode of Self-tuning Switching Gain

    Directory of Open Access Journals (Sweden)

    Jin Baoquan

    2012-11-01

    Full Text Available Aiming at the problem of tracking performance degradation of hydraulic EPC system caused by time-varying inertia parameters, nonlinear and external disturbances, the proportion sliding mode control of fuzzy self-tuning gain was proposed. The EPC system state space model on deviation parameters was established and the main feedback sliding mode switching algorithm was designed. The fuzzy method was used to dynamically adjust the proportion sliding mode switching gain by product of the switching function and its derivative state and to adaptive compensate for the uncertainty of the system. At the same time to ensure the effectiveness of the design strategy, the controller model and physical model worked together to simulate the actual conditions. The fixed switching gain switch was, respectively greater and smaller and compared with the fuzzy self-tuning gain, in which the latter achieves a fast and coordinated control of chattering. The results show that after comprehensive consideration all interference the system is stable, fast response, high accuracy and to solve chattering problem caused by the traditional large switching gain of proportion sliding mode.

  4. Reversible Recruitment of a Homeostatic Reserve Pool of Synaptic Vesicles Underlies Rapid Homeostatic Plasticity of Quantal Content.

    Science.gov (United States)

    Wang, Xueyong; Pinter, Martin J; Rich, Mark M

    2016-01-20

    Homeostatic regulation is essential for the maintenance of synaptic strength within the physiological range. The current study is the first to demonstrate that both induction and reversal of homeostatic upregulation of synaptic vesicle release can occur within seconds of blocking or unblocking acetylcholine receptors at the mouse neuromuscular junction. Our data suggest that the homeostatic upregulation of release is due to Ca(2+)-dependent increase in the size of the readily releasable pool (RRP). Blocking vesicle refilling prevented upregulation of quantal content (QC), while leaving baseline release relatively unaffected. This suggested that the upregulation of QC was due to mobilization of a distinct pool of vesicles that were rapidly recycled and thus were dependent on continued vesicle refilling. We term this pool the "homeostatic reserve pool." A detailed analysis of the time course of vesicle release triggered by a presynaptic action potential suggests that the homeostatic reserve pool of vesicles is normally released more slowly than other vesicles, but the rate of their release becomes similar to that of the major pool during homeostatic upregulation of QC. Remarkably, instead of finding a generalized increase in the recruitment of vesicles into RRP, we identified a distinct homeostatic reserve pool of vesicles that appear to only participate in synchronized release following homeostatic upregulation of QC. Once this small pool of vesicles is depleted by the block of vesicle refilling, homeostatic upregulation of QC is no longer observed. This is the first identification of the population of vesicles responsible for the blockade-induced upregulation of release previously described. Significance statement: The current study is the first to demonstrate that both the induction and reversal of homeostatic upregulation of synaptic vesicle release can occur within seconds. Our data suggest that homeostatic upregulation of release is due to Ca(2+)-dependent

  5. Continuous higher-order sliding mode control with time-varying gain for a class of uncertain nonlinear systems.

    Science.gov (United States)

    Han, Yaozhen; Liu, Xiangjie

    2016-05-01

    This paper presents a continuous higher-order sliding mode (HOSM) control scheme with time-varying gain for a class of uncertain nonlinear systems. The proposed controller is derived from the concept of geometric homogeneity and super-twisting algorithm, and includes two parts, the first part of which achieves smooth finite time stabilization of pure integrator chains. The second part conquers the twice differentiable uncertainty and realizes system robustness by employing super-twisting algorithm. Particularly, time-varying switching control gain is constructed to reduce the switching control action magnitude to the minimum possible value while keeping the property of finite time convergence. Examples concerning the perturbed triple integrator chains and excitation control for single-machine infinite bus power system are simulated respectively to demonstrate the effectiveness and applicability of the proposed approach.

  6. New results on the robust stability of PID controllers with gain and phase margins for UFOPTD processes.

    Science.gov (United States)

    Jin, Q B; Liu, Q; Huang, B

    2016-03-01

    This paper considers the problem of determining all the robust PID (proportional-integral-derivative) controllers in terms of the gain and phase margins (GPM) for open-loop unstable first order plus time delay (UFOPTD) processes. It is the first time that the feasible ranges of the GPM specifications provided by a PID controller are given for UFOPTD processes. A gain and phase margin tester is used to modify the original model, and the ranges of the margin specifications are derived such that the modified model can be stabilized by a stabilizing PID controller based on Hermite-Biehlers Theorem. Furthermore, we obtain all the controllers satisfying a given margin specification. Simulation studies show how to use the results to design a robust PID controller.

  7. The dependence of neuronal encoding efficiency on Hebbian plasticity and homeostatic regulation of neurotransmitter release

    Science.gov (United States)

    Faghihi, Faramarz; Moustafa, Ahmed A.

    2015-01-01

    Synapses act as information filters by different molecular mechanisms including retrograde messenger that affect neuronal spiking activity. One of the well-known effects of retrograde messenger in presynaptic neurons is a change of the probability of neurotransmitter release. Hebbian learning describe a strengthening of a synapse between a presynaptic input onto a postsynaptic neuron when both pre- and postsynaptic neurons are coactive. In this work, a theory of homeostatic regulation of neurotransmitter release by retrograde messenger and Hebbian plasticity in neuronal encoding is presented. Encoding efficiency was measured for different synaptic conditions. In order to gain high encoding efficiency, the spiking pattern of a neuron should be dependent on the intensity of the input and show low levels of noise. In this work, we represent spiking trains as zeros and ones (corresponding to non-spike or spike in a time bin, respectively) as words with length equal to three. Then the frequency of each word (here eight words) is measured using spiking trains. These frequencies are used to measure neuronal efficiency in different conditions and for different parameter values. Results show that neurons that have synapses acting as band-pass filters show the highest efficiency to encode their input when both Hebbian mechanism and homeostatic regulation of neurotransmitter release exist in synapses. Specifically, the integration of homeostatic regulation of feedback inhibition with Hebbian mechanism and homeostatic regulation of neurotransmitter release in the synapses leads to even higher efficiency when high stimulus intensity is presented to the neurons. However, neurons with synapses acting as high-pass filters show no remarkable increase in encoding efficiency for all simulated synaptic plasticity mechanisms. This study demonstrates the importance of cooperation of Hebbian mechanism with regulation of neurotransmitter release induced by rapid diffused retrograde

  8. The dependence of neuronal encoding efficiency on Hebbian plasticity and homeostatic regulation of neurotransmitter release

    Directory of Open Access Journals (Sweden)

    Faramarz eFaghihi

    2015-04-01

    Full Text Available Synapses act as information filters by different molecular mechanisms including retrograde messenger that affect neuronal spiking activity. One of the well-known effects of retrograde messenger in presynaptic neurons is a change of the probability of neurotransmitter release. Hebbian learning describe a strengthening of a synapse between a presynaptic input onto a postsynaptic neuron when both pre- and postsynaptic neurons are coactive. In this work, a theory of homeostatic regulation of neurotransmitter release by retrograde messenger and Hebbian plasticity in neuronal encoding is presented. Encoding efficiency was measured for different synaptic conditions. In order to gain high encoding efficiency, the spiking pattern of a neuron should be dependent on the intensity of the input and show low levels of noise. In this work, we represent spiking trains as zeros and ones (corresponding to non-spike or spike in a time bin, respectively as words with length equal to three. Then the frequency of each word (here eight words is measured using spiking trains. These frequencies are used to measure neuronal efficiency in different conditions and for different parameter values. Results show that neurons that have synapses acting as band-pass filters show the highest efficiency to encode their input when both Hebbian mechanism and homeostatic regulation of neurotransmitter release exist in synapses. Specifically, the integration of homeostatic regulation of feedback inhibition with Hebbian mechanism and homeostatic regulation of neurotransmitter release in the synapses leads to even higher efficiency when high stimulus intensity is presented to the neurons. However, neurons with synapses acting as high-pass filters show no remarkable increase in encoding efficiency for all simulated synaptic plasticity mechanisms.

  9. Control of transient gain absorption via tunneling and incoherent pumping in triple quantum dots

    Science.gov (United States)

    Tian, Si-Cong; Zhang, Xiao-Jun; Wan, Ren-Gang; Wang, Li-Jie; Shu, Shi-Li; Wang, Tao; Lu, Ze-Feng; Sun, Fang-Yuan; Tong, Cun-Zhu

    2017-01-01

    The transient gain-absorption properties of the probe field in vertical triple quantum dots assisted by double tunneling and incoherent pumping are investigated. With a proper intensity value and detuning of the second tunneling, the transient gain in triple quantum dots with incoherent pumping can be completely eliminated. In addition, the incoherent pumping affects both the amplitude of the transient absorption and the steady-state value. The dependence of transient behaviors on other parameters, such as the radiative decay rate and the pure dephasing decay rate of the quantum dots, is also discussed. The scheme may have important applications in quantum information networks and communication.

  10. An analytical method for PID controller tuning with specified gain and phase margins for integral plus time delay processes.

    Science.gov (United States)

    Hu, Wuhua; Xiao, Gaoxi; Li, Xiumin

    2011-04-01

    In this paper, an analytical method is proposed for proportional-integral/proportional-derivative/proportional-integral-derivative (PI/PD/PID) controller tuning with specified gain and phase margins (GPMs) for integral plus time delay (IPTD) processes. Explicit formulas are also obtained for estimating the GPMs resulting from given PI/PD/PID controllers. The proposed method indicates a general form of the PID parameters and unifies a large number of existing rules as PI/PD/PID controller tuning with various GPM specifications. The GPMs realized by existing PID tuning rules are computed and documented as a reference for control engineers to tune the PID controllers.

  11. A flexible and high-performance bidirectional optical amplifier with all optical gain control using ASE noise path through multi-port circulators

    Institute of Scientific and Technical Information of China (English)

    An Vu Tran; Chang-Joon Chae; Rodney S. Tucker

    2003-01-01

    We report a flexible all-optical gain controlled bidirectional optical amplifier. The device achieves constant gain and low noise figure over a large input power range. Moreover, the device removes Rayleigh backscattered light and amplifier noise.

  12. Electrical and optical control of optical gain in a coupled triple quantum dot system operating in telecommunication window

    Science.gov (United States)

    Mehmannavaz, Mohammad Reza; Sattari, Hamed

    2014-12-01

    We investigate the light amplification and gain without inversion (GWI) in triple quantum dot molecules in both steady-state and transient state. We demonstrate that the light amplification and GWI of a light pulse can be controlled through the rates of the incoherent pumping and tunneling between electronic levels. The required switching times for switching of a light pulse from absorption to gain and vice versa is then discussed. We obtain switching time at about 40 ps, which resembles a high-speed optical switch in nanostructure. The proposed approach in QDMs may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.

  13. Optimal camera exposure for video surveillance systems by predictive control of shutter speed, aperture, and gain

    Science.gov (United States)

    Torres, Juan; Menéndez, José Manuel

    2015-02-01

    This paper establishes a real-time auto-exposure method to guarantee that surveillance cameras in uncontrolled light conditions take advantage of their whole dynamic range while provide neither under nor overexposed images. State-of-the-art auto-exposure methods base their control on the brightness of the image measured in a limited region where the foreground objects are mostly located. Unlike these methods, the proposed algorithm establishes a set of indicators based on the image histogram that defines its shape and position. Furthermore, the location of the objects to be inspected is likely unknown in surveillance applications. Thus, the whole image is monitored in this approach. To control the camera settings, we defined a parameters function (Ef ) that linearly depends on the shutter speed and the electronic gain; and is inversely proportional to the square of the lens aperture diameter. When the current acquired image is not overexposed, our algorithm computes the value of Ef that would move the histogram to the maximum value that does not overexpose the capture. When the current acquired image is overexposed, it computes the value of Ef that would move the histogram to a value that does not underexpose the capture and remains close to the overexposed region. If the image is under and overexposed, the whole dynamic range of the camera is therefore used, and a default value of the Ef that does not overexpose the capture is selected. This decision follows the idea that to get underexposed images is better than to get overexposed ones, because the noise produced in the lower regions of the histogram can be removed in a post-processing step while the saturated pixels of the higher regions cannot be recovered. The proposed algorithm was tested in a video surveillance camera placed at an outdoor parking lot surrounded by buildings and trees which produce moving shadows in the ground. During the daytime of seven days, the algorithm was running alternatively together

  14. Fuzzy Gain Scheduling of PI Controller for Dual Star Induction Machine fed by a Matrix Converter

    OpenAIRE

    B. Meliani; A. Meroufel; H. Khouidmi

    2012-01-01

    The aim of this paper is to present a full digital implementation of a field orientation controlled Double Star induction Machine, and a PI controller is designed to control the speed, the machine is fed by a matrix converter. The advent of vector control technique has partially solved DSIM control problems because they are sensitive to drive parameter variations and performance may deteriorate if conventional controllers are used. Fuzzy logic and neural network Based controllers are consider...

  15. Compensation for secondary uncertainty in electro-hydraulic servo system by gain adaptive sliding mode variable structure control

    Institute of Scientific and Technical Information of China (English)

    ZHANG You-wang; GUI Wei-hua

    2008-01-01

    Based on consideration of the differential relations between the immeasurable variables and measurable variables in electro-hydraulic servo system, adaptive dynamic recurrent fuzzy neural networks(ADRFNNs) were employed to identify the primary uncertainty and the mathematic model of the system was turned into an equivalent linear model with terms of secondary uncertainty. At the same time, gain adaptive sliding mode variable structure control(GASMVSC) was employed to synthesize the control effort. The results show that the unrealization problem caused by some system's immeasurable state variables in traditional fuzzy neural networks(TFNN) taking all state variables as its inputs is overcome. On the other hand, the identification by the ADRFNNs online with high accuracy and the adaptive function of the correction term's gain in the GASMVSC make the system possess strong robustness and improved steady accuracy, and the chattering phenomenon of the control effort is also suppressed effectively.

  16. Coaxial GaAs-AlGaAs core-multishell nanowire lasers with epitaxial gain control

    Energy Technology Data Exchange (ETDEWEB)

    Stettner, T., E-mail: Thomas.Stettner@wsi.tum.de, E-mail: Gregor.Koblmueller@wsi.tum.de, E-mail: Jonathan.Finley@wsi.tum.de; Zimmermann, P.; Loitsch, B.; Regler, A.; Mayer, B.; Winnerl, J.; Matich, S.; Riedl, H.; Kaniber, M.; Abstreiter, G.; Koblmüller, G., E-mail: Thomas.Stettner@wsi.tum.de, E-mail: Gregor.Koblmueller@wsi.tum.de, E-mail: Jonathan.Finley@wsi.tum.de; Finley, J. J., E-mail: Thomas.Stettner@wsi.tum.de, E-mail: Gregor.Koblmueller@wsi.tum.de, E-mail: Jonathan.Finley@wsi.tum.de [Walter Schottky Institut and Physik Department, TU München, Garching 85748 (Germany); Döblinger, M. [Department of Chemistry, Ludwig-Maximilians-Universität München, Munich 81377 (Germany)

    2016-01-04

    We demonstrate the growth and single-mode lasing operation of GaAs-AlGaAs core-multishell nanowires (NW) with radial single and multiple GaAs quantum wells (QWs) as active gain media. When subject to optical pumping lasing emission with distinct s-shaped input-output characteristics, linewidth narrowing and emission energies associated with the confined QWs are observed. Comparing the low temperature performance of QW NW laser structures having 7 coaxial QWs with a nominally identical structure having only a single QW shows that the threshold power density reduces several-fold, down to values as low as ∼2.4 kW/cm{sup 2} for the multiple QW NW laser. This confirms that the individual radial QWs are electronically weakly coupled and that epitaxial design can be used to optimize the gain characteristics of the devices. Temperature-dependent investigations show that lasing prevails up to 300 K, opening promising new avenues for efficient III–V semiconductor NW lasers with embedded low-dimensional gain media.

  17. Homeostatic role of heterosynaptic plasticity: models and experiments

    Science.gov (United States)

    Chistiakova, Marina; Bannon, Nicholas M.; Chen, Jen-Yung; Bazhenov, Maxim; Volgushev, Maxim

    2015-01-01

    Homosynaptic Hebbian-type plasticity provides a cellular mechanism of learning and refinement of connectivity during development in a variety of biological systems. In this review we argue that a complimentary form of plasticity—heterosynaptic plasticity—represents a necessary cellular component for homeostatic regulation of synaptic weights and neuronal activity. The required properties of a homeostatic mechanism which acutely constrains the runaway dynamics imposed by Hebbian associative plasticity have been well-articulated by theoretical and modeling studies. Such mechanism(s) should robustly support the stability of operation of neuronal networks and synaptic competition, include changes at non-active synapses, and operate on a similar time scale to Hebbian-type plasticity. The experimentally observed properties of heterosynaptic plasticity have introduced it as a strong candidate to fulfill this homeostatic role. Subsequent modeling studies which incorporate heterosynaptic plasticity into model neurons with Hebbian synapses (utilizing an STDP learning rule) have confirmed its ability to robustly provide stability and competition. In contrast, properties of homeostatic synaptic scaling, which is triggered by extreme and long lasting (hours and days) changes of neuronal activity, do not fit two crucial requirements for a hypothetical homeostatic mechanism needed to provide stability of operation in the face of on-going synaptic changes driven by Hebbian-type learning rules. Both the trigger and the time scale of homeostatic synaptic scaling are fundamentally different from those of the Hebbian-type plasticity. We conclude that heterosynaptic plasticity, which is triggered by the same episodes of strong postsynaptic activity and operates on the same time scale as Hebbian-type associative plasticity, is ideally suited to serve a homeostatic role during on-going synaptic plasticity. PMID:26217218

  18. Homeostatic role of heterosynaptic plasticity: Models and experiments

    Directory of Open Access Journals (Sweden)

    Marina eChistiakova

    2015-07-01

    Full Text Available Homosynaptic Hebbian-type plasticity provides a cellular mechanism of learning and refinement of connectivity during development in a variety of biological systems. In this review we argue that a complimentary form of plasticity - heterosynaptic plasticity - represents a necessary cellular component for homeostatic regulation of synaptic weights and neuronal activity. The required properties of a homeostatic mechanism which acutely constrains the runaway dynamics imposed by Hebbian associative plasticity have been well-articulated by theoretical and modeling studies. Such mechanism(s should robustly support the stability of operation of neuronal networks and synaptic competition, include changes at non-active synapses, and operate on a similar time scale to Hebbian-type plasticity. The experimentally observed properties of heterosynaptic plasticity have introduced it as a strong candidate to fulfill this homeostatic role. Subsequent modeling studies which incorporate heterosynaptic plasticity into model neurons with Hebbian synapses (utilizing an STDP learning rule have confirmed its ability to robustly provide stability and competition. In contrast, properties of homeostatic synaptic scaling, which is triggered by extreme and long lasting (hours and days changes of neuronal activity, do not fit two crucial requirements for a hypothetical homeostatic mechanism needed to provide stability of operation in the face of on-going synaptic changes driven by Hebbian-type learning rules. Both the trigger and the time scale of homeostatic synaptic scaling are fundamentally different from those of the Hebbian-type plasticity. We conclude that heterosynaptic plasticity, which is triggered by the same episodes of strong postsynaptic activity and operates on the same time scale as Hebbian-type associative plasticity, is ideally suited to serve homeostatic role during on-going synaptic plasticity.

  19. Reason's Enemy Is Not Emotion: Engagement of Cognitive Control Networks Explains Biases in Gain/Loss Framing.

    Science.gov (United States)

    Li, Rosa; Smith, David V; Clithero, John A; Venkatraman, Vinod; Carter, R McKell; Huettel, Scott A

    2017-03-29

    In the classic gain/loss framing effect, describing a gamble as a potential gain or loss biases people to make risk-averse or risk-seeking decisions, respectively. The canonical explanation for this effect is that frames differentially modulate emotional processes, which in turn leads to irrational choice behavior. Here, we evaluate the source of framing biases by integrating functional magnetic resonance imaging data from 143 human participants performing a gain/loss framing task with meta-analytic data from >8000 neuroimaging studies. We found that activation during choices consistent with the framing effect were most correlated with activation associated with the resting or default brain, while activation during choices inconsistent with the framing effect was most correlated with the task-engaged brain. Our findings argue against the common interpretation of gain/loss framing as a competition between emotion and control. Instead, our study indicates that this effect results from differential cognitive engagement across decision frames.SIGNIFICANCE STATEMENT The biases frequently exhibited by human decision makers have often been attributed to the presence of emotion. Using a large fMRI sample and analysis of whole-brain networks defined with the meta-analytic tool Neurosynth, we find that neural activity during frame-biased decisions was more significantly associated with default behaviors (and the absence of executive control) than with emotion. These findings point to a role for neuroscience in shaping long-standing psychological theories in decision science.

  20. Preventing weight gain: the baseline weight related behaviors and delivery of a randomized controlled intervention in community based women

    Directory of Open Access Journals (Sweden)

    Teede Helena J

    2009-01-01

    Full Text Available Abstract Background Women aged 25–45 years represent a high risk group for weight gain and those with children are at increased risk because of weight gain associated with pregnancy and subsequent lifestyle change. Average self-reported weight gain is approximately 0.60 kg per year, and weight gain is associated with increased risk of chronic disease. There are barriers to reaching, engaging and delivering lifestyle interventions to prevent weight gain in this population. Methods This study investigated the baseline weight related behaviors and feasibility of recruiting and delivering a low intensity self-management lifestyle intervention to community based women with children in order to prevent weight gain, compared to standard education. The recruitment and delivery of the cluster-randomized controlled intervention was in conjunction with 12 primary (elementary schools. Baseline data collection included demographic, anthropometric, behavioral and biological measures. Results Two hundred and fifty community based women were randomized as clusters to intervention (n = 127 or control (n = 123. Mean age was 40.4 years (SD 4.7 and mean BMI 27.8 kg/m2 (SD 5.6. All components of this intervention were successfully delivered and retention rates were excellent, 97% at 4 months. Nearly all women (90% reported being dissatisfied with their weight and 72% attempted to self-manage their weight. Women were more confident of changing their diet (mean score 3.2 than physical activity (mean score 2.7. This population perceived they were engaging in prevention behaviors, with 71% reporting actively trying to prevent weight gain, yet they consumed a mean of 68 g fat/day (SD30 g and 27 g saturated fat/day (SD12 g representing 32% and 13% of energy respectively. The women had a high rate of dyslipidemia (33% and engaged in an average of 9187 steps/day (SD 3671. Conclusion Delivery of this low intensity intervention to a broad cross-section of community based

  1. Dynamic gain control with a matrix inequality approach to uncertain systems with triangular and non-triangular nonlinearities

    Science.gov (United States)

    Koo, Min-Sung; Choi, Ho-Lim

    2016-04-01

    We consider the global regulation problem of uncertain systems with both triangular and non-triangular nonlinearities. For the global regulation in the presence of non-triangular nonlinearities, we propose a dynamic gain controller designed by using power order conditions and a matrix inequality condition imposed on non-triangular nonlinearities. Compared with the existing results, the proposed control method allows a class of nonlinear systems that have not been treated before. Analysis and examples are given to prove the general applicability of our control method.

  2. Automatic Ship Handling of the Maritime Search Mission using a Self-Tuning Fuzzy Gain Scheduling PD Controller

    Science.gov (United States)

    Yu, Ker-Wei; Hwang, Rey-Chue; Hsieh, Jer-Guang

    In this paper, the ship manoeuvring problems particular to maritime search and rescue are investigated. A solution to such problems is necessary for successful ship handling to save human life. A fuzzy gain scheduling Proportional Derivative (PD) controller, using a back-propagation algorithm, is developed to solve these maritime search and rescue problems. The parameters of the proposed PD controller are determined on-line by fuzzy rules and adjustable fuzzy reasons. The proposed controller is self-adaptive and can accommodate the effects caused by wave or wind disturbance. Some computer simulations are provided to illustrate the use of the main ideas.

  3. Differential modulation of global and local neural oscillations in REM sleep by homeostatic sleep regulation

    Science.gov (United States)

    Kim, Bowon; Kocsis, Bernat; Hwang, Eunjin; Kim, Youngsoo; Strecker, Robert E.; McCarley, Robert W.; Choi, Jee Hyun

    2017-01-01

    Homeostatic rebound in rapid eye movement (REM) sleep normally occurs after acute sleep deprivation, but REM sleep rebound settles on a persistently elevated level despite continued accumulation of REM sleep debt during chronic sleep restriction (CSR). Using high-density EEG in mice, we studied how this pattern of global regulation is implemented in cortical regions with different functions and network architectures. We found that across all areas, slow oscillations repeated the behavioral pattern of persistent enhancement during CSR, whereas high-frequency oscillations showed progressive increases. This pattern followed a common rule despite marked topographic differences. The findings suggest that REM sleep slow oscillations may translate top-down homeostatic control to widely separated brain regions whereas fast oscillations synchronizing local neuronal ensembles escape this global command. These patterns of EEG oscillation changes are interpreted to reconcile two prevailing theories of the function of sleep, synaptic homeostasis and sleep dependent memory consolidation. PMID:28193862

  4. Cocaine addiction as a homeostatic reinforcement learning disorder.

    Science.gov (United States)

    Keramati, Mehdi; Durand, Audrey; Girardeau, Paul; Gutkin, Boris; Ahmed, Serge H

    2017-03-01

    Drug addiction implicates both reward learning and homeostatic regulation mechanisms of the brain. This has stimulated 2 partially successful theoretical perspectives on addiction. Many important aspects of addiction, however, remain to be explained within a single, unified framework that integrates the 2 mechanisms. Building upon a recently developed homeostatic reinforcement learning theory, the authors focus on a key transition stage of addiction that is well modeled in animals, escalation of drug use, and propose a computational theory of cocaine addiction where cocaine reinforces behavior due to its rapid homeostatic corrective effect, whereas its chronic use induces slow and long-lasting changes in homeostatic setpoint. Simulations show that our new theory accounts for key behavioral and neurobiological features of addiction, most notably, escalation of cocaine use, drug-primed craving and relapse, individual differences underlying dose-response curves, and dopamine D2-receptor downregulation in addicts. The theory also generates unique predictions about cocaine self-administration behavior in rats that are confirmed by new experimental results. Viewing addiction as a homeostatic reinforcement learning disorder coherently explains many behavioral and neurobiological aspects of the transition to cocaine addiction, and suggests a new perspective toward understanding addiction. (PsycINFO Database Record

  5. An assessment of overall open-loop "gain" of CO2-ventilation feedback control system in hypoxia.

    Science.gov (United States)

    Masuyama, H; Akiyama, S; Honda, Y

    1985-01-01

    Overall open-loop gain of the CO2-ventilation feedback control system in hypoxia (GHCO2) was determined on 8 male and one female healthy subjects. They breathed in a closed circuit, and were subjected to the progressive hypoxia test. This procedure was first conducted without dead space (DS), then with 250, 500, and finally 750 ml DS, consecutively. GHCO2 was calculated by dividing the slope of the CO2 response curve (S) by that of the metabolic hyperbola (SL). GHCO2 was considerably larger than the overall open-loop gain of the O2-ventilation feedback control system (GO2) previously obtained. This was ascribed to the facts that S was larger than the slope of the hypoxia response curve, and that the absolute value of SL in GHCO2 was smaller than that in GO2.

  6. Fuzzy Gain Scheduling of PI Controller for Dual Star Induction Machine fed by a Matrix Converter

    Directory of Open Access Journals (Sweden)

    B. Meliani

    2012-06-01

    Full Text Available The aim of this paper is to present a full digital implementation of a field orientation controlled Double Star induction Machine, and a PI controller is designed to control the speed, the machine is fed by a matrix converter. The advent of vector control technique has partially solved DSIM control problems because they are sensitive to drive parameter variations and performance may deteriorate if conventional controllers are used. Fuzzy logic and neural network Based controllers are considered as potential candidates for such an application. In this paper the fuzzy logic system is used on-line to generate the PI controller parameters. Simulink results for a 4.5 kW six-phase induction machine are presented and analyzed using a matlab environment. Obtained results demonstrated that the proposed control scheme is able to obtain high performances.

  7. Improved synthetic-heterodyne Michelson interferometer vibrometer using phase and gain control feedback.

    Science.gov (United States)

    Galeti, José Henrique; Kitano, Cláudio; Connelly, Michael J

    2015-12-10

    Synthetic-heterodyne demodulation is a useful technique for dynamic displacement and velocity measurement using interferometric sensors as it can provide an output signal which is immune to interferometric drift. With the advent of cost effective, high-speed real-time signal processing systems and software, processing of the complex signals encountered in interferometry has become more feasible. In conventional synthetic-heterodyne demodulation schemes, to obtain the dynamic displacement or vibration of the object under test requires knowledge of the interferometer visibility and also the argument of two Bessel functions. In this paper, a new synthetic-heterodyne demodulation method is described leading to an expression for the dynamic displacement and velocity of the object under test that is significantly less sensitive to the received optical power. In addition, the application of two independent phase and gain feedback loops is used to compensate for the nonideal gain and phase response of the anti-aliasing filter required for the signal acquisition of the received wideband interferometer signal. The efficacy of the improved system is demonstrated by measuring the displacement sensitivity frequency response and linearity of a Piezoelectric Mirror-Shifter (PMS) over a range of 200 Hz-9 kHz. In addition, the system is used to measure the response of the PMS to triangular and impulse type stimuli. The experimental results show excellent agreement with measurements taken using two independent industry standard calibration methods.

  8. The Impact of Weight Gain on Motivation, Compliance, and Metabolic Control in Patients with Type 2 Diabetes Mellitus

    OpenAIRE

    Pi-Sunyer, F. Xavier

    2009-01-01

    Patients with type 2 diabetes, approximately 85% of whom are overweight or obese, often have an increased incidence of cardiovascular disease (CVD) risk factors such as hypertension and dyslipidemia. Both type 2 diabetes and obesity are independent risk factors for CVD. Unfortunately, many therapies aimed at maintaining and improving glucose control are associated with weight gain. Among the older antidiabetes agents, most, including the insulin secretagogues and sensitizers, can lead to weig...

  9. Weight Gain Prevention among Midlife Women: A Randomized Controlled Trial to Address Needs Related to the Physical and Social Environment

    Directory of Open Access Journals (Sweden)

    Courtney D. Perry

    2016-05-01

    Full Text Available Women tend to gain weight at midlife (40–60 years increasing risk of obesity-related chronic diseases. Within specific eating occasions, needs related to the physical and social environment may result in less healthy eating behavior, which can lead to weight gain over time. The purpose of this study was to determine if a dietitian-delivered nutrition counseling intervention tailored to eating occasion needs could improve diet and prevent weight gain among midlife women over two years. A randomized controlled trial was conducted with healthy midlife women (n = 354 in one U.S. metropolitan area. The intervention group (n = 185 received ten hours of individual nutrition counseling from dietitians over six months, while women in a control group (n = 169 received no counseling. Measured height, weight and waist circumference, and dietary intakes were collected at baseline and every six months over two years. Mixed linear models were used to test for intervention effect on change in outcome variables over time. Dietary intakes of fruit, reduced/low-fat dairy foods and refined grains were significantly improved over time in the intervention compared to control group. However, the intervention had no effect on weight over time (p = 0.48. Nutrition counseling tailored to address eating occasion needs improved self-reported diet but did not significantly affect weight change.

  10. Adaptive Switching Gain for a Discrete-Time Sliding Mode Controller

    NARCIS (Netherlands)

    Monsees, G.; Scherpen, J.M.A.

    2000-01-01

    Sliding Mode Control is a well-known technique capable of making the closed loop system robust with respect to certain kinds of parameter variations and unmodeled dynamics. The sliding mode control law consists of the linear control part which is based on the model knowledge and the discontinuous co

  11. Second order sliding control with state dependent gain and its application to a hydraulic drive

    DEFF Research Database (Denmark)

    Schmidt, Lasse; Andersen, Torben Ole; Pedersen, Henrik C.

    2013-01-01

    The application of sliding modes for control of hydraulic drives appear promising due to strong robustness toward plant uncertainties and disturbances. Especially high order sliding modes may be successfully implemented avoiding the discontinuous control seen in first order sliding controls. Howe...

  12. Mapping homeostatic synaptic plasticity using cable properties of dendrites.

    Science.gov (United States)

    Queenan, B N; Lee, K J; Tan, H; Huganir, R L; Vicini, S; Pak, D T S

    2016-02-19

    When chronically silenced, cortical and hippocampal neurons homeostatically upregulate excitatory synaptic function. However, the subcellular position of such changes on the dendritic tree is not clear. We exploited the cable-filtering properties of dendrites to derive a parameter, the dendritic filtering index (DFI), to map the spatial distribution of synaptic currents. Our analysis indicates that young rat cortical neurons globally scale AMPA receptor-mediated currents, while mature hippocampal neurons do not, revealing distinct homeostatic strategies between brain regions and developmental stages. The DFI presents a useful tool for mapping the dendritic origin of synaptic currents and the location of synaptic plasticity changes.

  13. Switching Controller Design for a Class of Markovian Jump Nonlinear Systems Using Stochastic Small-Gain Theorem

    Directory of Open Access Journals (Sweden)

    Jin Zhu

    2009-01-01

    Full Text Available Switching controller design for a class of Markovian jump nonlinear systems with unmodeled dynamics is considered in this paper. Based on the differential equation and infinitesimal generator of jump systems, the concept of Jump Input-to-State practical Stability (JISpS in probability and stochastic Lyapunov stability criterion are put forward. By using backsetpping technology and stochastic small-gain theorem, a switching controller is proposed which ensures JISpS in probability for the jump nonlinear system. A simulation example illustrates the validity of this design.

  14. Homeostatic interplay between bacterial cell-cell signaling and iron in virulence.

    Directory of Open Access Journals (Sweden)

    Ronen Hazan

    2010-03-01

    Full Text Available Pathogenic bacteria use interconnected multi-layered regulatory networks, such as quorum sensing (QS networks to sense and respond to environmental cues and external and internal bacterial cell signals, and thereby adapt to and exploit target hosts. Despite the many advances that have been made in understanding QS regulation, little is known regarding how these inputs are integrated and processed in the context of multi-layered QS regulatory networks. Here we report the examination of the Pseudomonas aeruginosa QS 4-hydroxy-2-alkylquinolines (HAQs MvfR regulatory network and determination of its interaction with the QS acyl-homoserine-lactone (AHL RhlR network. The aim of this work was to elucidate paradigmatically the complex relationships between multi-layered regulatory QS circuitries, their signaling molecules, and the environmental cues to which they respond. Our findings revealed positive and negative homeostatic regulatory loops that fine-tune the MvfR regulon via a multi-layered dependent homeostatic regulation of the cell-cell signaling molecules PQS and HHQ, and interplay between these molecules and iron. We discovered that the MvfR regulon component PqsE is a key mediator in orchestrating this homeostatic regulation, and in establishing a connection to the QS rhlR system in cooperation with RhlR. Our results show that P. aeruginosa modulates the intensity of its virulence response, at least in part, through this multi-layered interplay. Our findings underscore the importance of the homeostatic interplay that balances competition within and between QS systems via cell-cell signaling molecules and environmental cues in the control of virulence gene expression. Elucidation of the fine-tuning of this complex relationship offers novel insights into the regulation of these systems and may inform strategies designed to limit infections caused by P. aeruginosa and related human pathogens.

  15. Adaptive switching gain for a discrete-time sliding mode controller

    NARCIS (Netherlands)

    Monsees, G.; Scherpen, J.M.A.

    2002-01-01

    Sliding mode control is a well-known technique capable of making the closed loop system robust with respect to certain kinds of parameter variations and unmodelled dynamics. The sliding mode control law consists of a continuous component which is based on the model knowledge and discontinuous compon

  16. Toward a Psychophysics of Agency: Detecting Gain and Loss of Control over Auditory Action Effects

    Science.gov (United States)

    Repp, Bruno H.; Knoblich, Gunther

    2007-01-01

    Theories of agency--the feeling of being in control of one's actions and their effects--emphasize either perceptual or cognitive aspects. This study addresses both aspects simultaneously in a finger-tapping paradigm. The tasks required participants to detect when synchronization of their taps with computer-controlled tones changed to…

  17. Gaining Control and Predictability of Software-Intensive Systems Development and Sustainment

    Science.gov (United States)

    2015-02-04

    this would be a major design driver for the software architect (Naegle & Petross, 2007). Primary Software Acquisition Problem Areas Addressed The...control and produces significantly more predictability in the program management realm. The research conclusions and recommendations are designed to...provide more control and predictability to software-intensive systems development. Due to the TOC and architectural design focus, system sustainability

  18. An assessment of overall "gain" of the O2-feedback control system with and without external dead space breathing.

    Science.gov (United States)

    Masuyama, H; Hayashi, F; Honda, Y

    1983-01-01

    Overall gain of the O2-ventilation feedback control system (GO2) was determined in 9 male and one female healthy subjects. GO2 progressively increased with decreasing end-tidal PO2 (PETO2). This value did not exceed the overall gain of the CO2-ventilation feedback system (GCO2) even at a PETO2 level of 40 mmHg, suggesting that hypoxic stimulation did not become predominant in the present experimental condition. With addition of 250 ml of external dead space, PETO2 decrement (delta PETO2 X actual) was experimentally observed. The delta PETO2 X actual thus obtained was found to be in good agreement with the PETO2 decrement deduced from GO2 (delta PETO2 X expected). This result was similar to that found in the PETCO2 change previously seen in normoxia.

  19. Stress- and diet-induced fat gain is controlled by NPY in catecholaminergic neurons.

    Science.gov (United States)

    Zhang, Lei; Lee, I-Chieh J; Enriquez, Rondaldo F; Lau, Jackie; Vähätalo, Laura H; Baldock, Paul A; Savontaus, Eriika; Herzog, Herbert

    2014-08-01

    Neuropeptide Y (NPY) and noradrenaline are commonly co-expressed in sympathetic neurons. Both are key regulators of energy homeostasis and critical for stress-coping. However, little is known about the specific function of NPY in the catecholaminergic system in these regulations. Here we show that mice with NPY expression only in the noradrenergic and adrenergic cells of the catecholaminergic system (catNPY) exhibited exacerbated diet-induced obesity, lower body and brown adipose tissue temperatures compared to WT and NPY(-/-) mice under a HFD. Furthermore, chronic stress increased adiposity and serum corticosterone level in WT but not NPY(-/-) mice. Re-introducing NPY specifically to the catecholaminergic system in catNPY mice restored stress responsiveness associated with increased respiratory exchange ratio and decreased liver pACC to tACC ratio. These results demonstrate catecholaminergic NPY signalling is critical in mediating diet- and chronic stress-induced fat gain via effects on diet-induced thermogenesis and stress-induced increases in corticosterone levels and lipogenic capacity.

  20. Storage for free: a surprising property of a simple gain-control model of motion aftereffects.

    Science.gov (United States)

    van de Grind, Wim A; van der Smagt, Maarten J; Verstraten, Frans A J

    2004-01-01

    If a motion aftereffect (MAE) for given adaptation conditions has a duration T s, and the eyes are closed after adaptation during a waiting period tw=T s before testing, an unexpected MAE of a 'residual' duration TrT s is experienced. This effect is called 'storage' and it is often quantified by a storage factor sigma=TrT/T, which can reach values up to about 0.7-0.8. The phenomenon and its name have invited explanations in terms of inhibition of recovery during darkness. We present a model based on the opposite idea, that an effective test stimulus quickens recovery relative to darkness or other ineffective test stimuli. The model is worked out in mathematical detail and proves to explain 'storage' data from the literature, on the static MAE (sMAE: an MAE experienced for static test stimuli). We also present results of a psychophysical experiment with moving random pixel arrays, quantifying storage phenomena both for the sMAE and the dynamic MAE (dMAE: an MAE experienced for a random dynamic noise test stimulus). Storage factors for the dMAE are lower than for the sMAE. Our model also gives an excellent description of these new data on storage of the dMAE. The term 'storage' might therefore be a misnomer. If an effective test stimulus influences all direction tuned motion sensors indiscriminately and thus speeds up equalization of gains, one gets the storage phenomenon for free.

  1. An integrated approach to the design of an aircraft gain scheduled controller

    OpenAIRE

    Berglund, Erik

    1995-01-01

    This thesis addresses the problem of integrated design of the aircraft plant parameters and of the corresponding feedback controller. The plant parameters are typically the sizes of the control surfaces or other aerodynamical surfaces of the aircraft. The approach is to rewrite the aircraft dynamic requirements as linear matrix inequalities (LMI's) and to optimize a linear cost function associated with aircraft plant parameters, while meeting the LMI constraints. An algorithm using Matlab and...

  2. Application of a New Membership Function in Nonlinear Fuzzy PID Controllers with Variable Gains

    Directory of Open Access Journals (Sweden)

    Xuda Zhang

    2014-01-01

    Full Text Available This paper proposes a nonlinear fuzzy PID control algorithm, whose membership function (MF is adjustable, is universal, and has a wide adjustable range. Appling this function to fuzzy control theory will increase system’s tunability. The continuity of this function is proved. This method was employed in the simulation and HIL experiments. Effectiveness and feasibility of this function are demonstrated in the results.

  3. Gain Scheduling Control of Gas Turbine Engines: Stability by Computing a Single Quadratic Lyapunov Function

    Science.gov (United States)

    2013-06-01

    STABILITY BY COMPUTING A SINGLE QUADRATIC LYAPUNOV FUNCTION Mehrdad Pakmehr∗ PhD Candidate Decision and Control Laboratory (DCL) School of Aerospace...linearization and linear matrix inequality (LMI) techniques. Using convex optimization tools, a single quadratic Lyapunov function is computed for multiple...Scheduling Control of Gas Turbine Engines: Stability by Computing a Single Quadratic Lyapunov Function 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  4. Simple adaptive pH control in bioreactors using gain-scheduling methods.

    Science.gov (United States)

    Gnoth, S; Kuprijanov, A; Simutis, R; Lübbert, A

    2010-01-01

    A simple well-performing adaptive control technique for pH control in fermentations of recombinant protein production processes is described and its design procedure is explained. First, the entire control algorithm was simulated and parameterized. Afterwards it was tested in real cultivation processes. The results show that this simple technique leads to significant reductions in the fluctuations of the pH values in microbial cultures at a minimum of expenditures. The signal-to-noise ratio and thus the information captured by the pH signal were increased by about an order of magnitude. This leads to a substantial improvement in the noise of many other process signals that are used to monitor and control the process. For instance, respiratory off-gas data of CO(2) and its derived carbon dioxide production rate signals from the cultures carry much less noise as compared to those values obtained with conventional pH control. Detailed process analysis revealed that even very small pH jumps of 0.03 values during the fermentation were shown to result in pronounced deflections in CO(2)-volume fraction of 8% (peak to peak). The proposed controller, maintaining the pH within the interval of 0.01 around the setpoint, reduces the noise considerably.

  5. Homeostatic Imbalance between Apoptosis and Cell Renewal in the Liver of Premature Aging XpdTTD Mice

    Science.gov (United States)

    Park, Jung Yoon; Cho, Mi-Ook; Leonard, Shanique; Calder, Brent; Mian, I. Saira; Kim, Woo Ho; Wijnhoven, Susan; van Steeg, Harry; Mitchell, James; van der Horst, Gijsbertus T. J.; Hoeijmakers, Jan; Cohen, Pinchas; Vijg, Jan; Suh, Yousin

    2008-01-01

    Unrepaired or misrepaired DNA damage has been implicated as a causal factor in cancer and aging. XpdTTD mice, harboring defects in nucleotide excision repair and transcription due to a mutation in the Xpd gene (R722W), display severe symptoms of premature aging but have a reduced incidence of cancer. To gain further insight into the molecular basis of the mutant-specific manifestation of age-related phenotypes, we used comparative microarray analysis of young and old female livers to discover gene expression signatures distinguishing XpdTTD mice from their age-matched wild type controls. We found a transcription signature of increased apoptosis in the XpdTTD mice, which was confirmed by in situ immunohistochemical analysis and found to be accompanied by increased proliferation. However, apoptosis rate exceeded the rate of proliferation, resulting in homeostatic imbalance. Interestingly, a metabolic response signature was observed involving decreased energy metabolism and reduced IGF-1 signaling, a major modulator of life span. We conclude that while the increased apoptotic response to endogenous DNA damage contributes to the accelerated aging phenotypes and the reduced cancer incidence observed in the XpdTTD mice, the signature of reduced energy metabolism is likely to reflect a compensatory adjustment to limit the increased genotoxic stress in these mutants. These results support a general model for premature aging in DNA repair deficient mice based on cellular responses to DNA damage that impair normal tissue homeostasis. PMID:18545656

  6. LMI-based gain scheduled controller synthesis for a class of linear parameter varying systems

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Anderson, Brian; Lanzon, Alexander

    2006-01-01

    This paper presents a novel method for constructing controllers for a class of single-input multiple-output (SIMO) linear parameter varying (LPV) systems. This class of systems encompasses many physical systems, in particular systems where individual components vary with time, and is therefore...... the parameters are varying, with the degree of stability related directly to a bound on the average rate of allowable parameter variations. Thus, if knowledge of the parameter variations is available, the conservativeness of the design can be kept at a minimum. The construction of the controller is formulated...

  7. On a small-gain approach to distributed event-triggered control

    NARCIS (Netherlands)

    De Persis, Claudio; Sailer, R.; Wirth, F.

    2011-01-01

    We consider large-scale systems stabilized by distributed controllers, which communicate over a limited shared medium. In this context it is of interest to reduce the communication load. An approach in this direction is eventtriggered sampling, which attempts only to send “relevant” data. In order t

  8. Sliding mode attitude control with L 2-gain performance and vibration reduction of flexible spacecraft with actuator dynamics

    Science.gov (United States)

    Hu, Qinglei

    2010-09-01

    This paper presents a dual-stage control system design method for the rotational maneuver control and vibration stabilization of a flexible spacecraft. In this design approach, the sub-systems of attitude control and vibration suppression are designed separately using the low order model. Based on the sliding mode control (SMC) theory, a discontinuous attitude control law in the form of the input voltage of the reaction wheel is derived to control the orientation of the spacecraft, incorporating the L 2-gain performance criterion constraint. The resulting closed-loop system is proven to be uniformly ultimately bounded stability and the effect of the external disturbance on both attitude quaternion and angular velocity can be attenuated to the prescribed level as well. In addition, an adaptive version of the control law is designed for adapting the unknown upper bounds of the lumped disturbance such that the limitation of knowing the bound of the disturbance in advance is released. For actively suppressing the induced vibration, strain rate feedback control method is also investigated by using piezoelectric materials as additional sensors and actuators bonded on the surface of the flexible appendages. Numerical simulations are performed to show that rotational maneuver and vibration suppression are accomplished in spite of the presence of disturbance and uncertainty.

  9. Actively phase-controlled coupling between plasmonic waveguides via in-between gain-assisted nanoresonator: nanoscale optical logic gates.

    Science.gov (United States)

    Ho, Kum-Song; Han, Yong-Ha; Ri, Chol-Song; Im, Song-Jin

    2016-08-15

    The development of nanoscale optical logic gates has attracted immense attention due to increasing demand for ultrahigh-speed and energy-efficient optical computing and data processing, however, suffers from the difficulty in precise control of phase difference of the two optical signals. We propose a novel conception of nanoscale optical logic gates based on actively phase-controlled coupling between two plasmonic waveguides via an in-between gain-assisted nanoresonator. Precise control of phase difference between the two plasmonic signals can be performed by manipulating pumping rate at an appropriate frequency detuning, enabling a high contrast between the output logic states "1" and "0." Without modification of the structural parameters, different logic functions can be provided. This active nanoscale optical logic device is expected to be quite energy-efficient with ideally low energy consumption on the order of 0.1 fJ/bit. Analytical calculations and numerical experiments demonstrate the validity of the proposed concept.

  10. Modeling and distributed gain scheduling strategy for load frequency control in smart grids with communication topology changes.

    Science.gov (United States)

    Liu, Shichao; Liu, Xiaoping P; El Saddik, Abdulmotaleb

    2014-03-01

    In this paper, we investigate the modeling and distributed control problems for the load frequency control (LFC) in a smart grid. In contrast with existing works, we consider more practical and real scenarios, where the communication topology of the smart grid changes because of either link failures or packet losses. These topology changes are modeled as a time-varying communication topology matrix. By using this matrix, a new closed-loop power system model is proposed to integrate the communication topology changes into the dynamics of a physical power system. The globally asymptotical stability of this closed-loop power system is analyzed. A distributed gain scheduling LFC strategy is proposed to compensate for the potential degradation of dynamic performance (mean square errors of state vectors) of the power system under communication topology changes. In comparison to conventional centralized control approaches, the proposed method can improve the robustness of the smart grid to the variation of the communication network as well as to reduce computation load. Simulation results show that the proposed distributed gain scheduling approach is capable to improve the robustness of the smart grid to communication topology changes.

  11. High-gain adaptive regulator for a string equation with uncertain harmonic disturbance under boundary output feedback control

    Institute of Scientific and Technical Information of China (English)

    Baozhu GUO; Wei GUO

    2003-01-01

    This paper considers the boundary stabilization and parameter estimation of a one-dimensional wave equation in the case when one end is fixed and control and harmonic disturbance with uncertain amplitude are input at another end. A high-gain adaptive regulator is designed in terms of measured collocated end velocity. The existence and uniqueness of the classical solution of the closed-loop system is proven. It is shown that the state of the system approaches the standstill as time goes to infitv and meanwhile, the estimated parameter converges to the unknown parameter.

  12. Gain Parameter Adjustment Methods Comparison of Controller for Autonomous Rehabilitation Device

    OpenAIRE

    Eski, Ikbal; Kirnap, Ahmet

    2016-01-01

    PID controller design and comparison between two different gainparameter adjustment method for autonomous physical rehabilitation device ispresented in this paper. This device will be capable of doing repeatedtherapeutic exercises of shoulder joint. That devices main objective  is reducing physiotherapist work load. Thecontrollers tested with real angel values. Comparison of simulation resultsshowed Ziegler_Nichols adjustment method has better performance than Matlab'sauto-tune method.

  13. Combinations of Stroke Neurorehabilitation to Facilitate Motor Recovery: Perspectives on Hebbian Plasticity and Homeostatic Metaplasticity

    Directory of Open Access Journals (Sweden)

    Naoyuki eTakeuchi

    2015-06-01

    Full Text Available Motor recovery after stroke involves developing new neural connections, acquiring new functions, and compensating for impairments. These processes are related to neural plasticity. Various novel stroke rehabilitation techniques based on basic science and clinical studies of neural plasticity have been developed to aid motor recovery. Current research aims to determine whether using combinations of these techniques can synergistically improve motor recovery. When different stroke neurorehabilitation therapies are combined, the timing of each therapeutic program must be considered to enable optimal neural plasticity. Synchronizing stroke rehabilitation with voluntary neural and/or muscle activity can lead to motor recovery by targeting Hebbian plasticity. This reinforces the neural connections between paretic muscles and the residual motor area. Homeostatic metaplasticity, which stabilizes the activity of neurons and neural circuits, can either augment or reduce the synergic effect depending on the timing of combination therapy and types of neurorehabilitation that are used. Moreover, the possibility that the threshold and degree of induced plasticity can be altered after stroke should be noted. This review focuses on the mechanisms underlying combinations of neurorehabilitation approaches and their future clinical applications. We suggest therapeutic approaches for cortical reorganization and maximal functional gain in patients with stroke, based on the processes of Hebbian plasticity and homeostatic metaplasticity. Few of the possible combinations of stroke neurorehabilitation have been tested experimentally; therefore, further studies are required to determine the appropriate combination for motor recovery.

  14. Integration and In-Field Gains Selection of Flight and Navigation Controller for Remotely Piloted Aircraft System

    Directory of Open Access Journals (Sweden)

    Słowik Maciej

    2017-03-01

    Full Text Available In the paper the implementation process of commercial flight and navigational controller in own aircraft is shown. The process of autopilot integration were performed for the fixed-wing type of unmanned aerial vehicle designed in high-wing and pull configuration of the drive. The above equipment were integrated and proper software control algorithms were chosen. The correctness of chosen hardware and software solution were verified in ground tests and experimental flights. The PID controllers for longitude and latitude controller channels were selected. The proper deflections of control surfaces and stabilization of roll, pitch and yaw angles were tested. In the next stage operation of telecommunication link and flight stabilization were verified. In the last part of investigations the preliminary control gains and configuration parameters for roll angle control loop were chosen. This enable better behavior of UAV during turns. Also it affected other modes of flight such as loiter (circle around designated point and auto mode where the plane executed a pre-programmed mission.

  15. A model-based gain scheduling approach for controlling the common-rail system for GDI engines

    Science.gov (United States)

    di Gaeta, Alessandro; Montanaro, Umberto; Fiengo, Giovanni; Palladino, Angelo; Giglio, Veniero

    2012-04-01

    The progressive reduction in vehicle emission requirements have forced the automotive industry to invest in research for developing alternative and more efficient control strategies. All control features and resources are permanently active in an electronic control unit (ECU), ensuring the best performance with respect to emissions, fuel economy, driveability and diagnostics, independently from engine working point. In this article, a considerable step forward has been achieved by the common-rail technology which has made possible to vary the injection pressure over the entire engine speed range. As a consequence, the injection of a fixed amount of fuel is more precise and multiple injections in a combustion cycle can be made. In this article, a novel gain scheduling pressure controller for gasoline direct injection (GDI) engine is designed to stabilise the mean fuel pressure into the rail and to track demanded pressure trajectories. By exploiting a simple control-oriented model describing the mean pressure dynamics in the rail, the control structure turns to be simple enough to be effectively implemented in commercial ECUs. Experimental results in a wide range of operating points confirm the effectiveness of the proposed control method to tame efficiently the mean value pressure dynamics of the plant showing a good accuracy and robustness with respect to unavoidable parameters uncertainties, unmodelled dynamics, and hidden coupling terms.

  16. Gain-scheduling control of a monocular vision-based human-following robot

    CSIR Research Space (South Africa)

    Burke, Michael G

    2011-08-01

    Full Text Available -to-point controller, which is less prone to losing a faster moving target, is preferred. The platform?s angular velocity input is then generated by the weighted sum ?(k) = ( |?(k)| ?max ) ?1(k) + ( 1? |?(k)| ?max ) ?2(k), (7) with ?max the maximum... be further refined through the use of a Kalman filter. We select the measurement uncertainty as one third of the typical pose variation in straight line motion, weighted by a factor w = 1 ? ni/nt. Here ni indicates the number of inliers returned...

  17. Histone Methylation by the Kleefstra Syndrome Protein EHMT1 Mediates Homeostatic Synaptic Scaling

    NARCIS (Netherlands)

    Benevento, M; Iacono, G.; Selten, M.M; Ba, W; Oudakker, A.R; Frega, M; Keller, J.; Mancini, R.; Lewerissa, E.; Kleefstra, T; Stunnenberg, H.G.; Zhou, H.; Bokhoven, H; Nadif Kasri, N

    2016-01-01

    Homeostatic plasticity, a form of synaptic plasticity, maintains the fine balance between overall excitation and inhibition in developing and mature neuronal networks. Although the synaptic mechanisms of homeostatic plasticity are well characterized, the associated transcriptional program remains po

  18. [Grazing systems, rotenone and parasites control in crossbred calves: effect on live weight gain and on parasites burdens].

    Science.gov (United States)

    Catto, João B; Bianchin, Ivo; Santurio, Jânio M; Feijó, Gelson L D; Kichel, Armindo N; Silva, José M da

    2009-01-01

    Practices for endo and ectoparasite control in beef cattle were evaluated in two independent experiments. First, the effects of rotenone on Rhipicephalus (Boophilus) microplus ticks were evaluated in vitro and in experimentally infected calves. In the second trial, the effects of grazing systems associated with endo and ectoparasite treatments on parasite burden and weight gain of naturally parasited animals were evaluated. Rotenone showed acaricide action on larvae and engorged ticks during in vitro tests and on larvae in experimentally infected calves. Three treatments with endectocide decreased (P parasited by horn fly, tick and larvae of Dermatobia hominis and the group treated with rotenone were significantly less parasited by horn fly in relation to control. Animals under rotational grazing showed significantly higher EPG than those under continuous grazing. Three treatments with endectocide in the dry season plus three acaricide treatments with fipronil in the raining season reduced EPG, tick, and screw worm larva counts, and provided a significant increase (23 kg) of live weight gain in relation to untreated animals.

  19. A Sigma-Delta ADC with Decimation and Gain Control Function for a Bluetooth Receiver in 130 nm Digital CMOS

    Directory of Open Access Journals (Sweden)

    Koh Jinseok

    2006-01-01

    Full Text Available We present a discrete-time second-order multibit sigma-delta ADC that filters and decimates by two the input data samples. At the same time it provides gain control function in its input sampling stage. A 4-tap FIR switched capacitor (SC architecture was chosen for antialiasing filtering. The decimation-by-two function is realized using divided-by-two clock signals in the antialiasing filter. Antialiasing, gain control, and sampling functions are merged in the sampling network using SC techniques. This compact architecture allows operating the preceding blocks at twice the ADC's clock frequency, thus improving the noise performance of the wireless receiver channel and relaxing settling requirements of the analog building blocks. The presented approach has been validated and incorporated in a commercial single-chip Bluetooth radio realized in a 1.5 V 130 nm digital CMOS process. The measured antialiasing filtering shows better than 75 dB suppression at the folding frequency band edge. A 67 dB dynamic range was measured with a sampling frequency of 37.5MHz.

  20. Homeostatic tendencies of the earth's atmosphere

    Science.gov (United States)

    Lovelock, J. E.; Margulis, L.

    1974-01-01

    The concept is developed that the atmosphere of the earth flows in a closed system controlled by and for the biosphere. The environmental factors delimiting the biosphere are examined. It is found that neither oxygen nor pressure per se limit the distribution of life as a whole. Rather the major physical variables determining the distribution of organisms are solar radiation, temperature, water abundance, and the concentrations of hydrogen and other ions and elements. An attempt is made to model temperature and atmospheric composition of a lifeless earth.

  1. Feasibility of a controlled trial aiming to prevent excessive pregnancy-related weight gain in primary health care

    Directory of Open Access Journals (Sweden)

    Weiderpass Elisabete

    2008-08-01

    Full Text Available Abstract Background Excessive gestational weight gain and postpartum weight retention may predispose women to long-term overweight and other health problems. Intervention studies aiming at preventing excessive pregnancy-related weight gain are needed. The feasibility of implementing such a study protocol in primary health care setting was evaluated in this pilot study. Methods A non-randomized controlled trial was conducted in three intervention and three control maternity and child health clinics in primary health care in Finland. Altogether, 132 pregnant and 92 postpartum women and 23 public health nurses (PHN participated in the study. The intervention consisted of individual counselling on physical activity and diet at five routine visits to a PHN and of an option for supervised group exercise until 37 weeks' gestation or ten months postpartum. The control clinics continued their usual care. The components of the feasibility evaluation were 1 recruitment and participation, 2 completion of data collection, 3 realization of the intervention and 4 the public health nurses' experiences. Results 1 The recruitment rate was slower than expected and the recruitment period had to be prolonged from the initially planned three months to six months. The average participation rate of eligible women at study enrolment was 77% and the drop-out rate 15%. 2 In total, 99% of the data on weight, physical activity and diet and 96% of the blood samples were obtained. 3 In the intervention clinics, 98% of the counselling sessions were realized, their contents and average durations were as intended, 87% of participants regularly completed the weekly records for physical activity and diet, and the average participation percentage in the group exercise sessions was 45%. 4 The PHNs regarded the extra training as a major advantage and the high additional workload as a disadvantage of the study. Conclusion The study protocol was mostly feasible to implement, which

  2. Homeostatic Disorders in Acute Poisoning by Psychotropic Agents

    Directory of Open Access Journals (Sweden)

    M. V. Belova

    2007-01-01

    Full Text Available Objective: to determine the impact of the degree of oxidative stress on homeostatic parameters in critically ill patients with acute poisoning by psychotropic agents (PTA.Materials and methods. The components of lipid peroxidation (LPO and the antioxidative system (AOS, blood rheological and immunological parameters, and the markers of endogenous intoxication were studied in 43 patients with severe acute PTA intoxication before and during intensive detoxification therapy.Results. The first hours of poisoning were marked by LPO-AOS imbalance with a significant preponderance of peroxidation processes, by impaired blood viscous properties, the manifestations of secondary immunodeficiency and endogenous intoxication. There were changes in the study parameters during detoxification therapy and at the early somatogenic stage of the disease.Conclusion. In patients with acute poisoning-induced critical conditions, the degree of oxidative stress affects the time course of homeostatic changes and determines the severity of endotoxicosis at all stages of the disease. 

  3. Homeostatic reinforcement learning for integrating reward collection and physiological stability.

    Science.gov (United States)

    Keramati, Mehdi; Gutkin, Boris

    2014-12-02

    Efficient regulation of internal homeostasis and defending it against perturbations requires adaptive behavioral strategies. However, the computational principles mediating the interaction between homeostatic and associative learning processes remain undefined. Here we use a definition of primary rewards, as outcomes fulfilling physiological needs, to build a normative theory showing how learning motivated behaviors may be modulated by internal states. Within this framework, we mathematically prove that seeking rewards is equivalent to the fundamental objective of physiological stability, defining the notion of physiological rationality of behavior. We further suggest a formal basis for temporal discounting of rewards by showing that discounting motivates animals to follow the shortest path in the space of physiological variables toward the desired setpoint. We also explain how animals learn to act predictively to preclude prospective homeostatic challenges, and several other behavioral patterns. Finally, we suggest a computational role for interaction between hypothalamus and the brain reward system.

  4. Weight gain is associated with improved glycaemic control but with adverse changes in plasma lipids and blood pressure isn Type 1 diabetes.

    LENUS (Irish Health Repository)

    Ferriss, J B

    2012-02-03

    AIMS: To assess the effects of weight gain on metabolic control, plasma lipids and blood pressure in patients with Type 1 diabetes. METHODS: Patients in the EURODIAB Prospective Complications Study (n = 3250) were examined at baseline and 1800 (55%) were re-examined a mean of 7.3 years later. Patients had Type 1 diabetes, defined as a diagnosis made before age 36 years and with a need for continuous insulin therapy within a year of diagnosis. Patients were aged 15-60 years at baseline and were stratified for age, sex and duration of diabetes. RESULTS: The change in HbA(1c) from baseline to follow-up examination was significantly more favourable in those who gained 5 kg or more during follow-up (\\'marked weight gain\\') than in patients who gained less or no weight or lost weight (\\'less or no weight gain\\'). In those with marked weight gain, there was a significantly greater rise in plasma triglycerides and total cholesterol and significantly less favourable changes in low-density lipoprotein and high-density lipoprotein cholesterol compared with those with less or no weight gain, with or without adjustment for HbA(1c). Systolic and diastolic blood pressure also rose significantly more in the group with marked weight gain. CONCLUSION: Weight gain in patients with Type 1 diabetes has adverse effects on plasma lipids and blood pressure, despite a small improvement in glycaemic control.

  5. Distributed cerebellar plasticity implements adaptable gain control in a manipulation task: a closed-loop robotic simulation

    Directory of Open Access Journals (Sweden)

    Jesus A Garrido Alcazar

    2013-10-01

    Full Text Available Adaptable gain regulation is at the core of the forward controller operation performed by the cerebro-cerebellar loops and it allows the intensity of motor acts to be finely tuned in a predictive manner. In order to learn and store information about body-object dynamics and to generate an internal model of movement, the cerebellum is thought to employ long-term synaptic plasticity. LTD at the PF-PC synapse has classically been assumed to subserve this function (Marr, 1969. However, this plasticity alone cannot account for the broad dynamic ranges and time scales of cerebellar adaptation. We therefore tested the role of plasticity distributed over multiple synaptic sites (Gao et al., 2012; Hansel et al., 2001 by generating an analog cerebellar model embedded into a control loop connected to a robotic simulator. The robot used a three-joint arm and performed repetitive fast manipulations with different masses along an 8-shape trajectory. In accordance with biological evidence, the cerebellum model was endowed with both LTD and LTP at the PF-PC, MF-DCN and PC-DCN synapses. This resulted in a network scheme whose effectiveness was extended considerably compared to one including just PF-PC synaptic plasticity. Indeed, the system including distributed plasticity reliably self-adapted to manipulate different masses and to learn the arm-object dynamics over a time course that included fast learning and consolidation, along the lines of what has been observed in behavioral tests. In particular, PF-PC plasticity operated as a time correlator between the actual input state and the system error, while MF-DCN and PC-DCN plasticity played a key role in generating the gain controller. This model suggests that distributed synaptic plasticity allows generation of the complex learning properties of the cerebellum. The incorporation of further plasticity mechanisms and of spiking signal processing will allow this concept to be extended in a more realistic

  6. Control of periodontal infections: a randomized controlled trial I. The primary outcome attachment gain and pocket depth reduction at treated sites.

    Science.gov (United States)

    Goodson, J Max; Haffajee, Anne D; Socransky, Sigmund S; Kent, Ralph; Teles, Ricardo; Hasturk, Hatice; Bogren, Anna; Van Dyke, Thomas; Wennstrom, Jan; Lindhe, Jan

    2012-06-01

    To compare the treatment outcome of scaling and root planing (SRP) in combination with systemic antibiotics, local antibiotic therapy and/or periodontal surgery. One hundred and eighty-seven patients were assigned to eight groups treated by SRP plus none, one, two or three adjunctive treatments and monitored for 24 months in a randomized controlled clinical trial using a 2 × 2 × 2 factorial design. Systemic amoxicillin + metronidazole (SMA), local tetracycline delivery (LTC) and periodontal surgery (SURG) were evaluated as adjuncts. Changes in clinical attachment level (CAL) and probing pocket depth (PPD) were statistically evaluated by ancova of main effects. Effects of adjunctive therapy to SRP were minimal at 3 months. Between 3 and 6 months PPD reduction occurred particularly in patients receiving periodontal surgery. After 6 months, both CAL gain and PPD reduction reached a plateau that was maintained at 24 months in all groups. The 24-month CAL gain was improved by SMA (0.50 mm) while PPD was reduced by SMA (0.51 mm) and SURG (0.36 mm). Smoking reduced CAL gain and PPD reduction. Patients receiving adjunctive therapies generally exhibited improved CAL gain and/or PPD reduction when compared with the outcome of SRP alone. Only additive, not synergistic effects of the various adjunctive therapies were observed. © 2012 John Wiley & Sons A/S.

  7. Nascent Proteome Remodeling following Homeostatic Scaling at Hippocampal Synapses.

    Science.gov (United States)

    Schanzenbächer, Christoph T; Sambandan, Sivakumar; Langer, Julian D; Schuman, Erin M

    2016-10-19

    Homeostatic scaling adjusts the strength of synaptic connections up or down in response to large changes in input. To identify the landscape of proteomic changes that contribute to opposing forms of homeostatic plasticity, we examined the plasticity-induced changes in the newly synthesized proteome. Cultured rat hippocampal neurons underwent homeostatic up-scaling or down-scaling. We used BONCAT (bio-orthogonal non-canonical amino acid tagging) to metabolically label, capture, and identify newly synthesized proteins, detecting and analyzing 5,940 newly synthesized proteins using mass spectrometry and label-free quantitation. Neither up- nor down-scaling produced changes in the number of different proteins translated. Rather, up- and down-scaling elicited opposing translational regulation of several molecular pathways, producing targeted adjustments in the proteome. We discovered ∼300 differentially regulated proteins involved in neurite outgrowth, axon guidance, filopodia assembly, excitatory synapses, and glutamate receptor complexes. We also identified differentially regulated proteins that are associated with multiple diseases, including schizophrenia, epilepsy, and Parkinson's disease.

  8. Adaptive fuzzy output-feedback controller design for nonlinear systems via backstepping and small-gain approach.

    Science.gov (United States)

    Liu, Zhi; Wang, Fang; Zhang, Yun; Chen, Xin; Chen, C L Philip

    2014-10-01

    This paper focuses on an input-to-state practical stability (ISpS) problem of nonlinear systems which possess unmodeled dynamics in the presence of unstructured uncertainties and dynamic disturbances. The dynamic disturbances depend on the states and the measured output of the system, and its assumption conditions are relaxed compared with the common restrictions. Based on an input-driven filter, fuzzy logic systems are directly used to approximate the unknown and desired control signals instead of the unknown nonlinear functions, and an integrated backstepping technique is used to design an adaptive output-feedback controller that ensures robustness with respect to unknown parameters and uncertain nonlinearities. This paper, by applying the ISpS theory and the generalized small-gain approach, shows that the proposed adaptive fuzzy controller guarantees the closed-loop system being semi-globally uniformly ultimately bounded. A main advantage of the proposed controller is that it contains only three adaptive parameters that need to be updated online, no matter how many states there are in the systems. Finally, the effectiveness of the proposed approach is illustrated by two simulation examples.

  9. Development of Digital Hysteresis Current Control with PLL Loop Gain Compensation Strategy for PWM Inverters with Constant Switching Frequency

    Directory of Open Access Journals (Sweden)

    N. Belhaouchet

    2008-03-01

    Full Text Available Hysteresis current control is one of the simplest techniques used to control the magnitude and phase angle of motor current for motor drives systems. However, this technique presents several disadvantages such as operation at variable switching frequency which can reveal problems of filtering, interference between the phases in the case of the three-phase systems with insulated neutral connection or delta connection, and irregularity of the modulation pulses which especially causes an acoustic noise on the level of the machine for the high power drive. In this paper, a new technique is proposed for a variable-hysteresis-band controller based on dead beat control applied to three phase voltage source PWM inverters feeding AC motors. Its main aim is firstly ensure a constant switching frequency and secondly the synchronization of modulation pulses using the phase-locked-loop with loop gain compensation in order to ensure a better stability. The behavior of the proposed technique is verified by simulation.

  10. Gaining control over responses to implicit attitude tests: Implementation intentions engender fast responses on attitude-incongruent trials.

    Science.gov (United States)

    Webb, Thomas L; Sheeran, Paschal; Pepper, John

    2012-03-01

    The present research investigated whether forming implementation intentions could promote fast responses to attitude-incongruent associations (e.g., woman-manager) and thereby modify scores on popular implicit measures of attitude. Expt 1 used the Implicit Association Test (IAT) to measure associations between gender and science versus liberal arts. Planning to associate women with science engendered fast responses to this category-attribute pairing and rendered summary scores more neutral compared to standard IAT instructions. Expt 2 demonstrated that forming egalitarian goal intentions is not sufficient to produce these effects. Expt 3 extended these findings to a different measure of implicit attitude (the Go/No-Go Association Task) and a different stereotypical association (Muslims-terrorism). In Expt 4, managers who planned to associate women with superordinate positions showed more neutral IAT scores relative to non-planners and effects were maintained 3 weeks later. In sum, implementation intentions enable people to gain control over implicit attitude responses.

  11. Gimbals Drive and Control Electronics Design, Development and Testing of the LRO High Gain Antenna and Solar Array Systems

    Science.gov (United States)

    Chernyakov, Boris; Thakore, Kamal

    2010-01-01

    Launched June 18, 2009 on an Atlas V rocket, NASA's Lunar Reconnaissance Orbiter (LRO) is the first step in NASA's Vision for Space Exploration program and for a human return to the Moon. The spacecraft (SC) carries a wide variety of scientific instruments and provides an extraordinary opportunity to study the lunar landscape at resolutions and over time scales never achieved before. The spacecraft systems are designed to enable achievement of LRO's mission requirements. To that end, LRO's mechanical system employed two two-axis gimbal assemblies used to drive the deployment and articulation of the Solar Array System (SAS) and the High Gain Antenna System (HGAS). This paper describes the design, development, integration, and testing of Gimbal Control Electronics (GCE) and Actuators for both the HGAS and SAS systems, as well as flight testing during the on-orbit commissioning phase and lessons learned.

  12. A gene-based information gain method for detecting gene-gene interactions in case-control studies.

    Science.gov (United States)

    Li, Jin; Huang, Dongli; Guo, Maozu; Liu, Xiaoyan; Wang, Chunyu; Teng, Zhixia; Zhang, Ruijie; Jiang, Yongshuai; Lv, Hongchao; Wang, Limei

    2015-11-01

    Currently, most methods for detecting gene-gene interactions (GGIs) in genome-wide association studies are divided into SNP-based methods and gene-based methods. Generally, the gene-based methods can be more powerful than SNP-based methods. Some gene-based entropy methods can only capture the linear relationship between genes. We therefore proposed a nonparametric gene-based information gain method (GBIGM) that can capture both linear relationship and nonlinear correlation between genes. Through simulation with different odds ratio, sample size and prevalence rate, GBIGM was shown to be valid and more powerful than classic KCCU method and SNP-based entropy method. In the analysis of data from 17 genes on rheumatoid arthritis, GBIGM was more effective than the other two methods as it obtains fewer significant results, which was important for biological verification. Therefore, GBIGM is a suitable and powerful tool for detecting GGIs in case-control studies.

  13. Determination of all feasible robust PID controllers for open-loop unstable plus time delay processes with gain margin and phase margin specifications.

    Science.gov (United States)

    Wang, Yuan-Jay

    2014-03-01

    This paper proposes a novel alternative method to graphically compute all feasible gain and phase margin specifications-oriented robust PID controllers for open-loop unstable plus time delay (OLUPTD) processes. This method is applicable to general OLUPTD processes without constraint on system order. To retain robustness for OLUPTD processes subject to positive or negative gain variations, the downward gain margin (GM(down)), upward gain margin (GM(up)), and phase margin (PM) are considered. A virtual gain-phase margin tester compensator is incorporated to guarantee the concerned system satisfies certain robust safety margins. In addition, the stability equation method and the parameter plane method are exploited to portray the stability boundary and the constant gain margin (GM) boundary as well as the constant PM boundary. The overlapping region of these boundaries is graphically determined and denotes the GM and PM specifications-oriented region (GPMSOR). Alternatively, the GPMSOR characterizes all feasible robust PID controllers which achieve the pre-specified safety margins. In particular, to achieve optimal gain tuning, the controller gains are searched within the GPMSOR to minimize the integral of the absolute error (IAE) or the integral of the squared error (ISE) performance criterion. Thus, an optimal PID controller gain set is successfully found within the GPMSOR and guarantees the OLUPTD processes with a pre-specified GM and PM as well as a minimum IAE or ISE. Consequently, both robustness and performance can be simultaneously assured. Further, the design procedures are summarized as an algorithm to help rapidly locate the GPMSOR and search an optimal PID gain set. Finally, three highly cited examples are provided to illustrate the design process and to demonstrate the effectiveness of the proposed method.

  14. Heat recovery gain more than doubled. Heat recovery system controller; Rueckwaermezahl mehr als verdoppelt. WRG-Controller

    Energy Technology Data Exchange (ETDEWEB)

    Voit, Christian [Kulle und Hofstetter, TGA Consulting, Muenchen (Germany); Niederer, Martin [Konvekta AG, St. Gallen (Switzerland)

    2009-03-15

    The hospital at Munich-Bogenhausen, which is a top level hospital with more than 1000 beds, modernised its heat recovery system first installed in the eighties of last century. A modern high-efficiency integrated recirculation system was installed instead. The system has a novel heat recovery controller which not only detects deviations from optimal operation but also identifies the causes. The system supplier, Konvekta AG of St.Gallen, Switzerland, is able to guarantee a heat recovery rate of 87 percent on a long-term basis. The energy cost for preheating of the ambient air was reduced by 78 percent as compared to the original system. (orig.)

  15. Homeostatic regulation of excitatory synapses on striatal medium spiny neurons expressing the D2 dopamine receptor.

    Science.gov (United States)

    Thibault, Dominic; Giguère, Nicolas; Loustalot, Fabien; Bourque, Marie-Josée; Ducrot, Charles; El Mestikawy, Salah; Trudeau, Louis-Éric

    2016-05-01

    Striatal medium spiny neurons (MSNs) are contacted by glutamatergic axon terminals originating from cortex, thalamus and other regions. The striatum is also innervated by dopaminergic (DAergic) terminals, some of which release glutamate as a co-transmitter. Despite evidence for functional DA release at birth in the striatum, the role of DA in the establishment of striatal circuitry is unclear. In light of recent work suggesting activity-dependent homeostatic regulation of glutamatergic terminals on MSNs expressing the D2 DA receptor (D2-MSNs), we used primary co-cultures to test the hypothesis that stimulation of DA and glutamate receptors regulates the homeostasis of glutamatergic synapses on MSNs. Co-culture of D2-MSNs with mesencephalic DA neurons or with cortical neurons produced an increase in spines and functional glutamate synapses expressing VGLUT2 or VGLUT1, respectively. The density of VGLUT2-positive terminals was reduced by the conditional knockout of this gene from DA neurons. In the presence of both mesencephalic and cortical neurons, the density of synapses reached the same total, compatible with the possibility of a homeostatic mechanism capping excitatory synaptic density. Blockade of D2 receptors increased the density of cortical and mesencephalic glutamatergic terminals, without changing MSN spine density or mEPSC frequency. Combined blockade of AMPA and NMDA glutamate receptors increased the density of cortical terminals and decreased that of mesencephalic VGLUT2-positive terminals, with no net change in total excitatory terminal density or in mEPSC frequency. These results suggest that DA and glutamate signaling regulate excitatory inputs to striatal D2-MSNs at both the pre- and postsynaptic level, under the influence of a homeostatic mechanism controlling functional output of the circuit.

  16. Fuzzy-Logic-Based Gain-Scheduling Control for State-of-Charge Balance of Distributed Energy Storage Systems for DC Microgrids

    DEFF Research Database (Denmark)

    Aldana, Nelson Leonardo Diaz; Dragicevic, Tomislav; Vasquez, Juan Carlos

    2014-01-01

    -charge or deep-discharge in one of the energy storage units. Primary control in a microgrid is responsible for power sharing among units; and droop control is typically used in this stage. This paper proposes a modular and decentralized gain-scheduling control strategy based on fuzzy logic that ensures balanced...

  17. A Double-Blind Randomized Controlled Trial of Maternal Postpartum Deworming to Improve Infant Weight Gain in the Peruvian Amazon

    Science.gov (United States)

    Casapía, Martín; Aguilar, Eder; Silva, Hermánn; Montresor, Antonio; Rahme, Elham; Fraser, William D.; Marquis, Grace S.; Vercruysse, Jozef; Allen, Lindsay H.; Blouin, Brittany; Razuri, Hugo; Pezo, Lidsky

    2017-01-01

    Background Nutritional interventions targeting the critical growth and development period before two years of age can have the greatest impact on health trajectories over the life course. Compelling evidence has demonstrated that interventions investing in maternal health in the first 1000 days of life are beneficial for both mothers and their children. One such potential intervention is deworming integrated into maternal postpartum care in areas where soil-transmitted helminth (STH) infections are endemic. Methodology/Principal Findings From February to August 2014, 1010 mother-infant pairs were recruited into a trial aimed at assessing the effectiveness of maternal postpartum deworming on infant and maternal health outcomes. Following delivery, mothers were randomly assigned to receive either single-dose 400 mg albendazole or placebo. Participants were followed-up at 1 and 6 months postpartum. There was no statistically significant difference in mean weight gain between infants in the experimental and control groups (mean difference: -0.02; 95% CI: -0.1, 0.08) at 6 months of age. Further, deworming had no effect on measured infant morbidity indicators. However, ad hoc analyses restricted to mothers who tested positive for STHs at baseline suggest that infants of mothers in the experimental group had greater mean length gain in cm (mean difference: 0.8; 95% CI: 0.1, 1.4) and length-for-age z-score (mean difference: 0.5; 95% CI: 0.2, 0.8) at 6 months of age. Conclusions/Significance In a study population composed of both STH-infected and uninfected mothers, maternal postpartum deworming was insufficient to impact infant growth and morbidity indicators up to 6 months postpartum. Among STH-infected mothers, however, important improvements in infant length gain and length-for-age were observed. The benefits of maternal postpartum deworming should be further investigated in study populations having higher overall prevalences and intensities of STH infections and, in

  18. Comparison of weight gain and energy intake after subthalamic versus pallidal stimulation in Parkinson's disease.

    Science.gov (United States)

    Sauleau, Paul; Leray, Emmanuelle; Rouaud, Tiphaine; Drapier, Sophie; Drapier, Dominique; Blanchard, Sophie; Drillet, Gwenolla; Péron, Julie; Vérin, Marc

    2009-10-30

    To compare body mass index (BMI) and daily energy intake (DEI) after subthalamic versus pallidal deep brain stimulation (DBS). Weight gain following DBS in Parkinson's disease patients remains largely unexplained and no comparison of subthalamic and pallidal (GPi) stimulation has yet been performed. BMI and DEI, dopaminergic drug administration and motor scores were recorded in 46 patients with PD before STN (n = 32) or GPi (n = 14) DBS and 3 and 6 months after. At M6, BMI had increased by an average of 8.4% in the STN group and 3.2% in the GPi group. BMI increased in 28 STN and 9 GPi patients. This increase was significantly higher in the STN group (P weight gain, inadequately explained by motor improvement or reduced dopaminergic drug dosage, occurred in subthalamic DBS patients. The difference between groups suggests additional factors in the STN group, such as homeostatic control center involvement.

  19. Fuzzy PI Controller Based Fault Analysis and Recovery in Sensorless BLDC Motor using High Gain Hybrid Converter (HGHC

    Directory of Open Access Journals (Sweden)

    R. Jayanthi

    2014-12-01

    Full Text Available Renewable Energy Sources (RES has been widely used in various applications due to increase in power demand. In this study, a High Gain Hybrid Converter (HGHC has been used to utilize maximum power from PV panel and to control the battery mode of operation such as charging/discharging in an efficient manner. In the load side, sensor less BLDC motor has been used in this study. After the back EMF is generated in the load side BLDC motor, it is taken as feedback to the HGHC. So, this will act as the main supply and thus, more power can be saved. Moreover, this research study also focuses on the transient analysis of the BLDC motor. The inverter in BLDC motor plays a vital role as it is responsible for flux generation and fixing up of angle ‘θ’ to the motor for its operation. So, the failures in the switches of the inverter would greatly affect the overall functioning of the BLDC motor. Thus, this research study focuses on the failure analysis of these switches in the inverter. In order to analyze and recover these faults, error controllers have been used in this proposed study. The simulations are carried out in MATLAB r2011a and the results are taken. The results show the significant performance of the proposed model.

  20. Neuropeptides function in a homeostatic manner to modulate excitation-inhibition imbalance in C. elegans.

    Science.gov (United States)

    Stawicki, Tamara M; Takayanagi-Kiya, Seika; Zhou, Keming; Jin, Yishi

    2013-05-01

    Neuropeptides play crucial roles in modulating neuronal networks, including changing intrinsic properties of neurons and synaptic efficacy. We previously reported a Caenorhabditis elegans mutant, acr-2(gf), that displays spontaneous convulsions as the result of a gain-of-function mutation in a neuronal nicotinic acetylcholine receptor subunit. The ACR-2 channel is expressed in the cholinergic motor neurons, and acr-2(gf) causes cholinergic overexcitation accompanied by reduced GABAergic inhibition in the locomotor circuit. Here we show that neuropeptides play a homeostatic role that compensates for this excitation-inhibition imbalance in the locomotor circuit. Loss of function in genes required for neuropeptide processing or release of dense core vesicles specifically modulate the convulsion frequency of acr-2(gf). The proprotein convertase EGL-3 is required in the cholinergic motor neurons to restrain convulsions. Electrophysiological recordings of neuromuscular junctions show that loss of egl-3 in acr-2(gf) causes a further reduction of GABAergic inhibition. We identify two neuropeptide encoding genes, flp-1 and flp-18, that together counteract the excitation-inhibition imbalance in acr-2(gf) mutants. We further find that acr-2(gf) causes an increased expression of flp-18 in the ventral cord cholinergic motor neurons and that overexpression of flp-18 reduces the convulsion of acr-2(gf) mutants. The effects of these peptides are in part mediated by two G-protein coupled receptors, NPR-1 and NPR-5. Our data suggest that the chronic overexcitation of the cholinergic motor neurons imposed by acr-2(gf) leads to an increased production of FMRFamide neuropeptides, which act to decrease the activity level of the locomotor circuit, thereby homeostatically modulating the excitation and inhibition imbalance.

  1. Neuropeptides function in a homeostatic manner to modulate excitation-inhibition imbalance in C. elegans.

    Directory of Open Access Journals (Sweden)

    Tamara M Stawicki

    2013-05-01

    Full Text Available Neuropeptides play crucial roles in modulating neuronal networks, including changing intrinsic properties of neurons and synaptic efficacy. We previously reported a Caenorhabditis elegans mutant, acr-2(gf, that displays spontaneous convulsions as the result of a gain-of-function mutation in a neuronal nicotinic acetylcholine receptor subunit. The ACR-2 channel is expressed in the cholinergic motor neurons, and acr-2(gf causes cholinergic overexcitation accompanied by reduced GABAergic inhibition in the locomotor circuit. Here we show that neuropeptides play a homeostatic role that compensates for this excitation-inhibition imbalance in the locomotor circuit. Loss of function in genes required for neuropeptide processing or release of dense core vesicles specifically modulate the convulsion frequency of acr-2(gf. The proprotein convertase EGL-3 is required in the cholinergic motor neurons to restrain convulsions. Electrophysiological recordings of neuromuscular junctions show that loss of egl-3 in acr-2(gf causes a further reduction of GABAergic inhibition. We identify two neuropeptide encoding genes, flp-1 and flp-18, that together counteract the excitation-inhibition imbalance in acr-2(gf mutants. We further find that acr-2(gf causes an increased expression of flp-18 in the ventral cord cholinergic motor neurons and that overexpression of flp-18 reduces the convulsion of acr-2(gf mutants. The effects of these peptides are in part mediated by two G-protein coupled receptors, NPR-1 and NPR-5. Our data suggest that the chronic overexcitation of the cholinergic motor neurons imposed by acr-2(gf leads to an increased production of FMRFamide neuropeptides, which act to decrease the activity level of the locomotor circuit, thereby homeostatically modulating the excitation and inhibition imbalance.

  2. Nonlinear feedback drives homeostatic plasticity in H2O2 stress response

    Science.gov (United States)

    Goulev, Youlian; Morlot, Sandrine; Matifas, Audrey; Huang, Bo; Molin, Mikael; Toledano, Michel B; Charvin, Gilles

    2017-01-01

    Homeostatic systems that rely on genetic regulatory networks are intrinsically limited by the transcriptional response time, which may restrict a cell’s ability to adapt to unanticipated environmental challenges. To bypass this limitation, cells have evolved mechanisms whereby exposure to mild stress increases their resistance to subsequent threats. However, the mechanisms responsible for such adaptive homeostasis remain largely unknown. Here, we used live-cell imaging and microfluidics to investigate the adaptive response of budding yeast to temporally controlled H2O2 stress patterns. We demonstrate that acquisition of tolerance is a systems-level property resulting from nonlinearity of H2O2 scavenging by peroxiredoxins and our study reveals that this regulatory scheme induces a striking hormetic effect of extracellular H2O2 stress on replicative longevity. Our study thus provides a novel quantitative framework bridging the molecular architecture of a cellular homeostatic system to the emergence of nonintuitive adaptive properties. DOI: http://dx.doi.org/10.7554/eLife.23971.001 PMID:28418333

  3. Homeostatic regulation of gephyrin scaffolds and synaptic strength at mature hippocampal GABAergic postsynapses.

    Science.gov (United States)

    Vlachos, Andreas; Reddy-Alla, Suneel; Papadopoulos, Theofilos; Deller, Thomas; Betz, Heinrich

    2013-11-01

    Gephyrin is a scaffolding protein important for the postsynaptic clustering of inhibitory neurotransmitter receptors. Here, we investigated the properties of gephyrin scaffolds at γ-aminobutyric acid- (GABA-)ergic synapses in organotypic entorhino-hippocampal cultures prepared from a transgenic mouse line, which expresses green fluorescent protein-tagged gephyrin under the control of the Thy1.2 promoter. Fluorescence recovery after photobleaching revealed a developmental stabilization of postsynaptic gephyrin clusters concomitant with an increase in cluster size and synaptic strength between 1 and 4 weeks in vitro. Prolonged treatment of the slice cultures with diazepam or a GABAA receptor antagonist disclosed a homeostatic regulation of both inhibitory synaptic strength and gephyrin cluster size and stability in 4-weeks-old cultures, whereas at 1 week in vitro, the same drug treatments modulated GABAergic postsynapse and gephyrin cluster properties following a Hebbian mode of synaptic plasticity. Our data are consistent with a model in which the postnatal maturation of the hippocampal network endows CA1 pyramidal neurons with the ability to homeostatically adjust the strength of their inhibitory postsynapses to afferent GABAergic drive by regulating gephyrin scaffold properties.

  4. MCTP is an ER-resident calcium sensor that stabilizes synaptic transmission and homeostatic plasticity

    Science.gov (United States)

    Genç, Özgür; Dickman, Dion K; Ma, Wenpei; Tong, Amy; Fetter, Richard D; Davis, Graeme W

    2017-01-01

    Presynaptic homeostatic plasticity (PHP) controls synaptic transmission in organisms from Drosophila to human and is hypothesized to be relevant to the cause of human disease. However, the underlying molecular mechanisms of PHP are just emerging and direct disease associations remain obscure. In a forward genetic screen for mutations that block PHP we identified mctp (Multiple C2 Domain Proteins with Two Transmembrane Regions). Here we show that MCTP localizes to the membranes of the endoplasmic reticulum (ER) that elaborate throughout the soma, dendrites, axon and presynaptic terminal. Then, we demonstrate that MCTP functions downstream of presynaptic calcium influx with separable activities to stabilize baseline transmission, short-term release dynamics and PHP. Notably, PHP specifically requires the calcium coordinating residues in each of the three C2 domains of MCTP. Thus, we propose MCTP as a novel, ER-localized calcium sensor and a source of calcium-dependent feedback for the homeostatic stabilization of neurotransmission. DOI: http://dx.doi.org/10.7554/eLife.22904.001 PMID:28485711

  5. Spectrum efficiency gains resulting from the implementation of adaptive transmit power control in fixed terrestrial links at 38 GHz

    Science.gov (United States)

    Callaghan, S. A.; Inglis, I.; Hansell, P.

    2009-06-01

    Adaptive transmit power control (ATPC) can be used to improve the spectrum efficiency of terrestrial point-to-point fixed links by limiting the transmit power to that required to maintain a constant bit error rate regardless of the propagation conditions. This results in a reduced transmit power being used during clear-sky conditions, lowering the interference resulting from the ATPC link. This improves the frequency reuse factor associated with a given band and geographic area, providing a spectrum efficiency gain. The project described in this paper found that implementing ATPC in the 38 GHz terrestrial fixed links band gives significant improvements in spectrum efficiency as measured by the increase in the number of links assigned to channel 1 (from ˜50% to ˜70%) and the decrease in the maximum bandwidth used (from ˜300 MHz to ˜180 MHz). However, a model plan exposed to an exceptionally intense frontal rain event showed a number of additional outages caused by ATPC, amounting to approximately 12% of the number of outages caused directly by rain. In comparison, when exposed to an annualized simulated rain database the number of extra outages in this case falls to 2.6%.

  6. Comparison of dual-time-constant and fast-acting automatic gain control (AGC) systems in cochlear implants.

    Science.gov (United States)

    Boyle, Patrick J; Büchner, Andreas; Stone, Michael A; Lenarz, Thomas; Moore, Brian C J

    2009-04-01

    Cochlear implants usually employ an automatic gain control (AGC) system as a first stage of processing. AGC1 was a fast-acting (syllabic) compressor. AGC2 was a dual-time-constant system; it usually performed as a slow-acting compressor, but incorporated an additional fast-acting system to provide protection from sudden increases in sound level. Six experienced cochlear-implant users were tested in a counterbalanced order, receiving one-month of experience with a given AGC type before switching to the other type. Performance was evaluated shortly after provision of a given AGC type and after one-month of experience with that AGC type. Questionnaires, mainly relating to listening in quiet situations, did not reveal significant differences between the two AGC types. However, fixed-level and roving-level tests of sentence identification in noise both revealed significantly better performance for AGC2. It is suggested that the poorer performance for AGC1 occurred because AGC1 introduced cross-modulation between the target speech and background noise, which made perceptual separation of the target and background more difficult.

  7. Detailed description of a prepregnancy care program and its impact on maternal glucose control, weight gain, and dropouts.

    Science.gov (United States)

    Perea, Verónica; Orois, Aida; Amor, Antonio J; Jansà, Marga; Vidal, Merce; Gimenez, Marga; Conget, Ignacio; Vinagre, Irene

    2017-02-01

    The aim of this study was to analyze the clinical and metabolic changes observed during a prepregnancy care (PPC) program. We performed a retrospective, observational, cohort study of 104 women with type 1 diabetes initiating a PPC program from 2011 to 2014. The outcomes measured were changes in HbA1c levels, weight and hypoglycemic events during PPC. Risk factors associated with severe hypoglycemia events, achieving the HbA1c target and dropouts were evaluated. HbA1c decreased from 7.2 ± 0.8% (55.3 ± 8.8 mmol/mol) to 6.7 ± 0.9% (49.8 ± 10.3 mmol/mol) (P < .001) within a median of 14.2 months (interquartile interval 5.4-23.2); 71.2% obtained HbA1c  < 7% (53 mmol/mol). HbA1c at the end of PPC was associated with baseline HbA1c (β = .318, P = .001) and the number of previous pregnancies (β = .224, P = .038), PPC was accompanied by 1.4 ± 4.0 kg weight gain (P = .003) without changes in severe hypoglycemic events. The risk factors for severe hypoglycemia were severe hypoglycemic events during the 2 years before (odds ratio [OR] 11.99, confidence interval 95% 1.89-75.95) and PPC duration (OR 1.09, 1.03-1.16). A total of 33 patients (31.7%) dropped out from PPC during follow-up, with dropout being associated with age (OR 1.17, 1.04-1.36) and PPC duration (OR 1.06, 1.02-1.11). Our PPC program was associated with an improvement in glycemic control without a significant increase in severe hypoglycemic events, although with some weight gain. A considerable number of patients dropped out during follow-up, this being related to older age and a longer duration of the program. This information could be of help to design new and more effective PPC approaches. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Reinforcement processes in opiate addiction: a homeostatic model.

    Science.gov (United States)

    Schulteis, G; Koob, G F

    1996-11-01

    The development of tolerance and dependence has traditionally been considered an integral aspect of the drug addiction process, and opiate dependence has been studied extensively as a model system in this regard. However, recent emphasis on the positive reinforcing properties of drugs has led to the suggestion that tolerance, dependence, and withdrawal may be of secondary or even negligible importance in motivating compulsive drug use. The current article argues for an integrated view of addiction in the form of a homeostatic neuroadaptation model which emphasizes the motivational significance of both the positive affective state produced by opiates and the negative affective state characteristic of drug withdrawal. The model is supported by evidence at both the behavioral and neural systems levels of analysis. Understanding the important distinction between somatic and affective components of opiate withdrawal is key to recognizing the factors which contribute to the motivational significance of opiate dependence and withdrawal. In addition, the critical role of conditioning processes in the maintenance of compulsive drug use and relapse after periods of abstention is discussed. Finally, it is argued that both the positive reinforcement produced by acute administration of a drug and the negative affective state produced by withdrawal are common to multiple classes of abused drugs, suggesting that an understanding of homeostatic neuroadaptation within motivational systems provides a key to the etiology, treatment and prevention of drug addiction.

  9. Homeostatic Imbalance in Epithelial Ducts and Its Role in Carcinogenesis

    Directory of Open Access Journals (Sweden)

    Katarzyna A. Rejniak

    2012-01-01

    Full Text Available An epithelial duct is a well-defined multicellular structure composed of tightly packed cells separating and protecting body compartments that are used for enzyme secretion and its transport across the internal. The structural and functional integrity (homeostasis of such ducts is vital in carrying many life functions (breathing, lactation, production of hormones. However, the processes involved in maintaining the homeostatic balance are not yet fully understood. On the other hand, the loss of epithelial tissue architecture, such as filled lumens or ductal disorganization, are among the first symptoms of the emerging epithelial tumors (carcinomas. Using the previously developed biomechanical model of epithelial ducts: IBCell, we investigated how different signals and mechanical stimuli imposed on individual epithelial cells can impact the homeostatic (imbalance and integrity of the whole epithelial tissue. We provide a link between erroneous responses of individual epithelial cells to specific signals and the emerging ductal morphologies characteristic for preinvasive cancers observed in pathology specimens, or characteristic for multicellular structures arising from mutated cells cultured in vitro. We summarize our finding in terms of altered properties of epithelial cell polarization, and discuss the relative importance of various polarization signals on the formation of tumor-like multicellular structures.

  10. Homeostatic imbalance in epithelial ducts and its role in carcinogenesis.

    Science.gov (United States)

    Rejniak, Katarzyna A

    2012-01-01

    An epithelial duct is a well-defined multicellular structure composed of tightly packed cells separating and protecting body compartments that are used for enzyme secretion and its transport across the internal. The structural and functional integrity (homeostasis) of such ducts is vital in carrying many life functions (breathing, lactation, production of hormones). However, the processes involved in maintaining the homeostatic balance are not yet fully understood. On the other hand, the loss of epithelial tissue architecture, such as filled lumens or ductal disorganization, are among the first symptoms of the emerging epithelial tumors (carcinomas). Using the previously developed biomechanical model of epithelial ducts: IBCell, we investigated how different signals and mechanical stimuli imposed on individual epithelial cells can impact the homeostatic (im)balance and integrity of the whole epithelial tissue. We provide a link between erroneous responses of individual epithelial cells to specific signals and the emerging ductal morphologies characteristic for preinvasive cancers observed in pathology specimens, or characteristic for multicellular structures arising from mutated cells cultured in vitro. We summarize our finding in terms of altered properties of epithelial cell polarization, and discuss the relative importance of various polarization signals on the formation of tumor-like multicellular structures.

  11. Homeostatic responses by surviving cortical pyramidal cells in neurodegenerative tauopathy.

    Science.gov (United States)

    Crimins, Johanna L; Rocher, Anne B; Peters, Alan; Shultz, Penny; Lewis, Jada; Luebke, Jennifer I

    2011-11-01

    Cortical neuron death is prevalent by 9 months in rTg(tau(P301L))4510 tau mutant mice (TG) and surviving pyramidal cells exhibit dendritic regression and spine loss. We used whole-cell patch-clamp recordings to investigate the impact of these marked structural changes on spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs) of layer 3 pyramidal cells in frontal cortical slices from behaviorally characterized TG and non-transgenic (NT) mice at this age. Frontal lobe function of TG mice was intact following a short delay interval but impaired following a long delay interval in an object recognition test, and cortical atrophy and cell loss were pronounced. Surviving TG cells had significantly reduced dendritic diameters, total spine density, and mushroom spines, yet sEPSCs were increased and sIPSCs were unchanged in frequency. Thus, despite significant regressive structural changes, synaptic responses were not reduced in TG cells, indicating that homeostatic compensatory mechanisms occur during progressive tauopathy. Consistent with this idea, surviving TG cells were more intrinsically excitable than NT cells, and exhibited sprouting of filopodia and axonal boutons. Moreover, the neuropil in TG mice showed an increased density of asymmetric synapses, although their mean size was reduced. Taken together, these data indicate that during progressive tauopathy, cortical pyramidal cells compensate for loss of afferent input by increased excitability and establishment of new synapses. These compensatory homeostatic mechanisms may play an important role in slowing the progression of neuronal network dysfunction during neurodegenerative tauopathies.

  12. L-band automatic-gain-controlled erbium-doped fiber amplifier utilizing C-band backward-amplified spontaneous emission and electrical feedback monitor.

    Science.gov (United States)

    Shen, Jyi-Lai; Lee, Yueh-Chien; Huang, Chia-Chih

    2009-02-10

    A new L-band automatic-gain-controlled (AGC) erbium-doped fiber amplifier (EDFA) for dense wavelength-division-multiplexing transmission systems is presented, in which a single 1480 nm laser with an internal thermoelectric cooler is used as a primary pump for stable amplification. All C-band amplified spontaneous emission (ASE) is recycled by the secondary pump to enhance the gain efficiency. A fraction of the output signal is used as an electrical feedback monitor for the AGC to improve the gain-clamped (GC) flatness. Experimental results prove that the AGC EDFA has a gain flatness of better than 0.46 dB/40 nm, i.e., below 1.5%, and a higher gain of approximately 36.5 dB compared to that of approximately 35.3 dB for the conventional GC EDFA at -30 dBm input signal power. The best gain flatness of +/-0.25 dB can be achieved over the dynamic range greater than 20 dB. The dynamic range of noise figure is between 6.7 and 7.1. The 3 dB down bandwidth is more than 40 nm. Overall dynamics measurements for the AGC EDFA feedback stabilization have been carried out. The recorded corresponding rise time of 1.565 ms indicates that the system does not exhibit any overshoot of gain or ASE variation due to the signal at the beginning of the pulse.

  13. A low-power high-performance configurable auto-gain control loop for a digital hearing aid SoC

    Science.gov (United States)

    Chengying, Chen; Hainan, Liu; Yong, Hei; Jun, Fan; Xiaoyu, Hu

    2013-10-01

    A low-power, configurable auto-gain control loop for a digital hearing aid system on a chip (SoC) is presented. By adopting a mixed-signal feedback control structure and peak detection and judgment, it can work in automatic gain or variable gain control modes through a digital signal processing unit. A noise-reduction and dynamic range (DR) improvement technique is also used to ensure the DR of the circuit in a low-voltage supply. The circuit is implemented in an SMIC 0.13 μm 1P8M CMOS process. The measurement results show that in a 1 V power supply, 1.6 kHz input frequency and 200 mVp—p, the SFDR is 74.3 dB, the THD is 66.1 dB, and the total power is 89 μW, meeting the application requirements of hearing aid SoCs.

  14. Prolonged vestibular stimulation induces homeostatic plasticity of the vestibulo-ocular reflex in larval Xenopus laevis.

    Science.gov (United States)

    Dietrich, Haike; Straka, Hans

    2016-07-01

    Vestibulo-ocular reflexes (VOR) stabilise retinal images during head/body motion in vertebrates by generating spatio-temporally precise extraocular motor commands for corrective eye movements. While VOR performance is generally robust with a relatively stable gain, cerebellar circuits are capable of adapting the underlying sensory-motor transformation. Here, we studied cerebellum-dependent VOR plasticity by recording head motion-induced lateral rectus and superior oblique extraocular motor discharge in semi-intact preparations of Xenopus laevis tadpoles. In the absence of visual feedback, prolonged sinusoidal rotation caused either an increase or decrease of the VOR gain depending on the motion stimulus amplitude. The observed changes in extraocular motor discharge gradually saturated after 20 min of constant rotation and returned to baseline in the absence of motion stimulation. Furthermore, plastic changes in lateral rectus and superior oblique motor commands were plane-specific for horizontal and vertical rotations, respectively, suggesting that alterations are restricted to principal VOR connections. Comparison of multi- and single-unit activity indicated that plasticity occurs in all recorded units of a given extraocular motor nucleus. Ablation of the cerebellum abolished motoneuronal gain changes and prevented the induction of plasticity, thus demonstrating that both acquisition and retention of this type of plasticity require an intact cerebellar circuitry. In conclusion, the plane-specific and stimulus intensity-dependent modification of the VOR gain through the feed-forward cerebellar circuitry represents a homeostatic plasticity that likely maintains an optimal working range for the underlying sensory-motor transformation.

  15. All-optical pulse data generation in a semiconductor optical amplifier gain controlled by a reshaped optical clock injection

    Science.gov (United States)

    Lin, Gong-Ru; Chang, Yung-Cheng; Yu, Kun-Chieh

    2006-05-01

    Wavelength-maintained all-optical pulse data pattern transformation based on a modified cross-gain-modulation architecture in a strongly gain-depleted semiconductor optical amplifier (SOA) is investigated. Under a backward dark-optical-comb injection with 70% duty-cycle reshaping from the received data clock at 10GHz, the incoming optical data stream is transformed into a pulse data stream with duty cycle, rms timing jitter, and conversion gain of 15%, 4ps, and 3dB, respectively. The high-pass filtering effect of the gain-saturated SOA greatly improves the extinction ratio of data stream by 8dB and reduces its bit error rate to 10-12 at -18dBm.

  16. Solutions to the cocktail party problem in insects: selective filters, spatial release from masking and gain control in tropical crickets.

    Directory of Open Access Journals (Sweden)

    Arne K D Schmidt

    Full Text Available Insects often communicate by sound in mixed species choruses; like humans and many vertebrates in crowded social environments they thus have to solve cocktail-party-like problems in order to ensure successful communication with conspecifics. This is even more a problem in species-rich environments like tropical rainforests, where background noise levels of up to 60 dB SPL have been measured.Using neurophysiological methods we investigated the effect of natural background noise (masker on signal detection thresholds in two tropical cricket species Paroecanthus podagrosus and Diatrypa sp., both in the laboratory and outdoors. We identified three 'bottom-up' mechanisms which contribute to an excellent neuronal representation of conspecific signals despite the masking background. First, the sharply tuned frequency selectivity of the receiver reduces the amount of masking energy around the species-specific calling song frequency. Laboratory experiments yielded an average signal-to-noise ratio (SNR of -8 dB, when masker and signal were broadcast from the same side. Secondly, displacing the masker by 180° from the signal improved SNRs by further 6 to 9 dB, a phenomenon known as spatial release from masking. Surprisingly, experiments carried out directly in the nocturnal rainforest yielded SNRs of about -23 dB compared with those in the laboratory with the same masker, where SNRs reached only -14.5 and -16 dB in both species. Finally, a neuronal gain control mechanism enhances the contrast between the responses to signals and the masker, by inhibition of neuronal activity in interstimulus intervals.Thus, conventional speaker playbacks in the lab apparently do not properly reconstruct the masking noise situation in a spatially realistic manner, since under real world conditions multiple sound sources are spatially distributed in space. Our results also indicate that without knowledge of the receiver properties and the spatial release mechanisms the

  17. Regulation of Blood Glucose Concentration in Type 1 Diabetics Using Single Order Sliding Mode Control Combined with Fuzzy On-line Tunable Gain, a Simulation Study.

    Science.gov (United States)

    Dinani, Soudabeh Taghian; Zekri, Maryam; Kamali, Marzieh

    2015-01-01

    Diabetes is considered as a global affecting disease with an increasing contribution to both mortality rate and cost damage in the society. Therefore, tight control of blood glucose levels has gained significant attention over the decades. This paper proposes a method for blood glucose level regulation in type 1 diabetics. The control strategy is based on combining the fuzzy logic theory and single order sliding mode control (SOSMC) to improve the properties of sliding mode control method and to alleviate its drawbacks. The aim of the proposed controller that is called SOSMC combined with fuzzy on-line tunable gain is to tune the gain of the controller adaptively. This merit causes a less amount of control effort, which is the rate of insulin delivered to the patient body. As a result, this method can decline the risk of hypoglycemia, a lethal phenomenon in regulating blood glucose level in diabetics caused by a low blood glucose level. Moreover, it attenuates the chattering observed in SOSMC significantly. It is worth noting that in this approach, a mathematical model called minimal model is applied instead of the intravenously infused insulin-blood glucose dynamics. The simulation results demonstrate a good performance of the proposed controller in meal disturbance rejection and robustness against parameter changes. In addition, this method is compared to fuzzy high-order sliding mode control (FHOSMC) and the superiority of the new method compared to FHOSMC is shown in the results.

  18. Sleep homeostatic pressure and PER3 VNTR gene polymorphism influence antidepressant response to sleep deprivation in bipolar depression.

    Science.gov (United States)

    Dallaspezia, Sara; Locatelli, Clara; Lorenzi, Cristina; Pirovano, Adele; Colombo, Cristina; Benedetti, Francesco

    2016-03-01

    Combined Total sleep deprivation (TSD) and light therapy (LT) cause a rapid improvement in bipolar depression which has been hypothesized to be paralleled by changes in sleep homeostasis. Recent studies showed that bipolar patients had lower changes of EEG theta power after sleep and responders to antidepressant TSD+LT slept less and showed a lower increase of EEG theta power then non-responders. A polymorphism in PER3 gene has been associated with diurnal preference, sleep structure and homeostatic response to sleep deprivation in healthy subjects. We hypothesized that the individual variability in the homeostatic response to TSD could be a correlate of antidepressant response and be influenced by genetic factors. We administered three TSD+LT cycles to bipolar depressed patients. Severity of depression was rated on Hamilton Depression Rating Scale. Actigraphic recordings were performed in a group of patients. PER3 polymorphism influenced changes in total sleep time (F=2.24; p=0.024): while PER3(4/4) and PER3(4/5) patients showed a reduction in it after treatment, PER3(5/5) subjects showed an increase of about 40min, suggesting a higher homeostatic pressure. The same polymorphism influenced the change of depressive symptomatology during treatment (F=3.72; p=0.028). Sleep information was recorded till the day after the end of treatment: a longer period of observation could give more information about the possible maintenance of allostatic adaptation. A higher sleep homeostatic pressure reduced the antidepressant response to TSD+LT, while an allostatic adaptation to sleep loss was associated with better response. This process seems to be under genetic control. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Controlling slow and fast light and dynamic pulse-splitting with tunable optical gain in a whispering-gallery-mode microcavity

    Science.gov (United States)

    Asano, M.; Özdemir, Ş. K.; Chen, W.; Ikuta, R.; Yang, L.; Imoto, N.; Yamamoto, T.

    2016-05-01

    We report controllable manipulation of slow and fast light in a whispering-gallery-mode microtoroid resonator fabricated from Erbium (Er3+) doped silica. We observe continuous transition of the coupling between the fiber-taper waveguide and the microresonator from undercoupling to critical coupling and then to overcoupling regimes by increasing the pump power even though the spatial distance between the resonator and the waveguide was kept fixed. This, in turn, enables switching from fast to slow light and vice versa just by increasing the optical gain. An enhancement of delay of two-fold over the passive silica resonator (no optical gain) was observed in the slow light regime. Moreover, we show dynamic pulse splitting and its control in slow/fast light systems using optical gain.

  20. Controlling slow and fast light and dynamic pulse-splitting with tunable optical gain in a whispering-gallery-mode microcavity

    CERN Document Server

    Asano, Motoki; Chen, Weijian; Ikuta, Rikizo; Yang, Lan; Imoto, Nobuyuki; Yamamoto, Takashi

    2016-01-01

    We report controllable manipulation of slow and fast light in a whispering-gallery-mode (WGM) microtoroid resonator fabricated from Erbium (Er3+) doped silica. We observe continuous transition of the coupling between the fiber-taper waveguide and the microresonator from undercoupling to critical coupling and then to overcoupling regimes by increasing the pump power even though the spatial distance between the resonator and the waveguide was kept fixed. This, in turn, enables switching from fast to slow light and vice versa just by increasing the optical gain. An enhancement of delay of two-fold over the passive silica resonator (no optical gain) was observed in the slow light regime. Moreover, we show dynamic pulse splitting and its control in slow/fast light systems using optical gain.

  1. Enhancing depression mechanisms in midbrain dopamine neurons achieves homeostatic resilience.

    Science.gov (United States)

    Friedman, Allyson K; Walsh, Jessica J; Juarez, Barbara; Ku, Stacy M; Chaudhury, Dipesh; Wang, Jing; Li, Xianting; Dietz, David M; Pan, Nina; Vialou, Vincent F; Neve, Rachael L; Yue, Zhenyu; Han, Ming-Hu

    2014-04-18

    Typical therapies try to reverse pathogenic mechanisms. Here, we describe treatment effects achieved by enhancing depression-causing mechanisms in ventral tegmental area (VTA) dopamine (DA) neurons. In a social defeat stress model of depression, depressed (susceptible) mice display hyperactivity of VTA DA neurons, caused by an up-regulated hyperpolarization-activated current (I(h)). Mice resilient to social defeat stress, however, exhibit stable normal firing of these neurons. Unexpectedly, resilient mice had an even larger I(h), which was observed in parallel with increased potassium (K(+)) channel currents. Experimentally further enhancing Ih or optogenetically increasing the hyperactivity of VTA DA neurons in susceptible mice completely reversed depression-related behaviors, an antidepressant effect achieved through resilience-like, projection-specific homeostatic plasticity. These results indicate a potential therapeutic path of promoting natural resilience for depression treatment.

  2. Dynamic interplay among homeostatic, hedonic, and cognitive feedback circuits regulating body weight.

    Science.gov (United States)

    Hall, Kevin D; Hammond, Ross A; Rahmandad, Hazhir

    2014-07-01

    Obesity is associated with a prolonged imbalance between energy intake and expenditure, both of which are regulated by multiple feedback processes within and across individuals. These processes constitute 3 hierarchical control systems-homeostatic, hedonic, and cognitive-with extensive interaction among them. Understanding complex eating behavior requires consideration of all 3 systems and their interactions. Existing models of these processes are widely scattered, with relatively few attempts to integrate across mechanisms. We briefly review available empirical evidence and dynamic models, discussing challenges and potential for better integration. We conclude that developing richer models of dynamic interplay among systems should be a priority in the future study of obesity and that systems science modeling offers the potential to aid in this goal.

  3. Homeostatic regulation of Salmonella-induced mucosal inflammation and injury by IL-23.

    Directory of Open Access Journals (Sweden)

    Muyiwa Awoniyi

    Full Text Available IL-12 and IL-23 regulate innate and adaptive immunity to microbial pathogens through influencing the expression of IFN-γ, IL-17, and IL-22. Herein we define the roles of IL-12 and IL-23 in regulating host resistance and intestinal inflammation during acute Salmonella infection. We find that IL-23 alone is dispensable for protection against systemic spread of bacteria, but synergizes with IL-12 for optimal protection. IL-12 promotes the production of IFN-γ by NK cells, which is required for resistance against Salmonella and also for induction of intestinal inflammation and epithelial injury. In contrast, IL-23 controls the severity of inflammation by inhibiting IL-12A expression, reducing IFN-γ and preventing excessive mucosal injury. Our studies demonstrate that IL-23 is a homeostatic regulator of IL-12-dependent, IFN-γ-mediated intestinal inflammation.

  4. Preventing weight gain by lifestyle intervention in a general practice setting - three-year results of a randomized controlled trial

    NARCIS (Netherlands)

    ter Bogt, Nancy C. W.; Bemelmans, Wanda J. E.; Beltman, Frank W.; Broer, Jan; Smit, Andries J.; van der Meer, Klaas

    2011-01-01

    Background: Weight regain after initial loss of weight is common, which indicates a need for lifestyle counseling aimed at preventing weight gain instead of weight loss. This study was conducted to determine whether structured lifestyle counseling by nurse practitioners (NPs) group compared with usu

  5. 26 CFR 1.355-6 - Recognition of gain on certain distributions of stock or securities in controlled corporation.

    Science.gov (United States)

    2010-04-01

    ... recommendation, 20 unrelated individuals each purchases 30 shares of the outstanding D stock. Each client's... that clients purchase D stock, the trustee of several trusts qualified under section 401(a) sponsored... 26 Internal Revenue 4 2010-04-01 2010-04-01 false Recognition of gain on certain distributions...

  6. Homeostatic plasticity in human motor cortex demonstrated by two consecutive sessions of paired associative stimulation.

    Science.gov (United States)

    Müller, J Florian M; Orekhov, Yuriy; Liu, Yali; Ziemann, Ulf

    2007-06-01

    Long-term potentiation (LTP) and long-term depression (LTD) underlie most models of learning and memory, but neural activity would grow or shrink in an uncontrolled manner, if not guarded by stabilizing mechanisms. The Bienenstock-Cooper-Munro (BCM) rule proposes a sliding threshold for LTP/LTD induction: LTP induction becomes more difficult if neural activity was high previously. Here we tested if this form of homeostatic plasticity applies to the human motor cortex (M1) in vivo by examining the interactions between two consecutive sessions of paired associative stimulation (PAS). PAS consisted of repeated pairs of electrical stimulation of the right median nerve followed by transcranial magnetic stimulation of the left M1. The first PAS session employed an interstimulus interval equalling the individual N20-latency of the median nerve somatosensory-evoked cortical potential plus 2 ms, N20-latency minus 5 ms, or a random alternation between these intervals, to induce an LTP-like increase in motor-evoked potential (MEP) amplitudes in the right abductor pollicis brevis muscle (PAS(LTP)), an LTD-like decrease (PAS(LTD)), or no change (PAS(Control)), respectively. The second PAS session 30 min later was always PAS(LTP). It induced an moderate LTP-like effect if conditioned by PAS(Control), which increased if conditioned by PAS(LTD), but decreased if conditioned by PAS(LTP). Effects on MEP amplitude induced by the second PAS session exhibited a negative linear correlation with those in the first PAS session. Because the two PAS sessions activate identical neuronal circuits, we conclude that 'homosynaptic-like' homeostatic mechanisms in accord with the BCM rule contribute to regulating plasticity in human M1.

  7. A 0.04 mm (2) Buck-Boost DC-DC Converter for Biomedical Implants Using Adaptive Gain and Discrete Frequency Scaling Control.

    Science.gov (United States)

    George, Libin; Gargiulo, Gaetano Dario; Lehmann, Torsten; Hamilton, Tara Julia

    2016-06-01

    This paper presents the design of a reconfigurable buck-boost switched-capacitor DC-DC converter suitable for use in a wide range of biomedical implants. The proposed converter has an extremely small footprint and uses a novel control method that allows coarse and fine control of the output voltage. The converter uses adaptive gain control, discrete frequency scaling and pulse-skipping schemes to regulate the power delivered to a range of output voltages and loads. Adaptive gain control is used to implement variable switching gain ratios from a reconfigurable power stage and thereby make coarse steps in output voltage. A discrete frequency scaling controller makes discrete changes in switching frequency to vary the power delivered to the load and perform fine tuning when the output voltage is within 10% of the target output voltage. The control architecture is predominately digital and it has been implemented as part of a fully-integrated switched-capacitor converter design using a standard bulk CMOS 0.18 μm process. Measured results show that the converter has an output voltage range of 1.0 to 2.2 V, can deliver up to 7.5 mW of load power and efficiency up to 75% using an active area of only 0.04 mm (2), which is significantly smaller than that of other designs. This low-area, low-complexity reconfigurable power converter can support low-power circuits in biomedical implant applications.

  8. Ultrasonic testing of canning tubes in stainless steel of the EL 4 reactor; Controle par ultrasons des tubes de gaine en acier inoxydable du reacteur EL 4

    Energy Technology Data Exchange (ETDEWEB)

    Prot, A.; Monnier, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    From all the methods possible for controlling thin cans the one chosen, for numerous reasons, vas that making use of ultrasonic techniques. A method has been developed which should make it possible to carry out a rapid and efficient industrial control of canning tubes, The reasons for the choice of the ultrasonic method are given in detail, together with the principles of the method and the actual control parameters. In the present state of our research, it should be possible to control at least 50 000 tubes a year. Improvements brought about in the details of the control technique itself should make it possible to increase this rate considerably. (authors) [French] Parmi toutes les methodes possibles de controle des gaines minces, le procede retenu pour de multiples raisons a ete celui faisant appel a la technique des ultrasons. Une methode a ete mise au point qui doit permettre un controle industriel rapide et efficace des tubes de gaine. Sont exposes en detail, les raisons du choix de la methode par ultrasons, les principes de cette methode et les parametres du controle proprement dit. Dans l'etat actuel de nos etudes la cadence devrait permettre le controle de 50000 tubes par an au minimum. Des ameliorations de detail portant sur la technique de controle elle-meme, doivent permettre d'accelerer tres notablement cette cadence. (auteurs)

  9. Light-scattering properties of a woven shade-screen material used for daylighting and solar heat-gain control

    Energy Technology Data Exchange (ETDEWEB)

    Jonsson, Jacob; Jonsson, Jacob C.; Lee, Eleanor S.; Rubin, Mike

    2008-08-01

    Shade-screens are widely used in commercial buildings as a way to limit the amount of direct sunlight that can disturb people in the building. The shade screens also reduce the solar heat-gain through glazing the system. Modern energy and daylighting analysis software such as EnergyPlus and Radiance require complete scattering properties of the scattering materials in the system. In this paper a shade screen used in the LBNL daylighting testbed is characterized using a photogoniometer and a normal angle of incidence integrating sphere. The data is used to create a complete bi-directional scattering distribution function (BSDF) that can be used in simulation programs. The resulting BSDF is compared to a model BADFs, both directly and by calculating the solar heat-gain coefficient for a dual pane system using Window 6.

  10. An novel analog programmable power supply for active gain control of the Multi-Pixel Photon Counter (MPPC)

    CERN Document Server

    Li, Zhengwei; Xu, Yupeng; Yan, Bo; Li, Yanguo; Lu, Xuefeng; Li, Xufang; Zhang, Shuo; Chang, Zhi; Li, Jicheng; Zhang, Yifei; Zhao, Jianling

    2016-01-01

    Silicon Photo-Multipliers (SiPM) are regarded as novel photo-detector to replace conventional Photo-Multiplier Tubes (PMTs). However, the breakdown voltage dependence on the ambient temperature results in a gain variation of $\\sim$3$\\% /^{\\circ} \\mathrm C$. This can severely limit the application of this device in experiments with wide range of operating temperature, especially in space telescope. An experimental setup in dark condition was established to investigate the temperature and bias voltage dependence of gain for the Multi-Pixel Photon Counter (MPPC), one type of the SiPM developed by Hamamatsu. The gain and breakdown voltage dependence on operating temperature of an MPPC can be approximated by a linear function, which is similar to the behavior of a zener diode. The measured temperature coefficient of the breakdown voltage is $(59.4 \\pm 0.4$ mV)$/^{\\circ} \\mathrm C$. According to this fact, a programmable power supply based on two zener diodes and an operational amplifier was designed with a positiv...

  11. Fish and mammalian phagocytes differentially regulate pro-inflammatory and homeostatic responses in vivo.

    Directory of Open Access Journals (Sweden)

    Aja M Rieger

    Full Text Available Phagocytosis is a cellular mechanism that is important to the early induction of antimicrobial responses and the regulation of adaptive immunity. At an inflammatory site, phagocytes serve as central regulators for both pro-inflammatory and homeostatic anti-inflammatory processes. However, it remains unclear if this is a recent evolutionary development or whether the capacity to balance between these two seemingly contradictory processes is a feature already displayed in lower vertebrates. In this study, we used murine (C57BL/6 and teleost fish (C. auratus in vitro and in vivo models to assess the evolutionary conservation of this dichotomy at a site of inflammation. At the level of the macrophage, we found that teleost fish already displayed divergent pro-inflammatory and homeostatic responses following internalization of zymosan or apoptotic bodies, respectively, and that these were consistent with those of mice. However, fish and mice displayed significant differences in vivo with regards to the level of responsiveness to zymosan and apoptotic bodies, the identity of infiltrating leukocytes, their rate of infiltration, and the kinetics and strength of resulting antimicrobial responses. Unlike macrophages, significant differences were identified between teleost and murine neutrophilic responses. We report for the first time that activated murine, but not teleost neutrophils, possess the capacity to internalize apoptotic bodies. This internalization translates into reduction of neutrophil ROS production. This may play an important part in the recently identified anti-inflammatory activity that mammalian neutrophils display during the resolution phase of inflammation. Our observations are consistent with continued honing of inflammatory control mechanisms from fish to mammals, and provide added insights into the evolutionary path that has resulted in the integrated, multilayered responses that are characteristic of higher vertebrates.

  12. Modeling circadian and sleep-homeostatic effects on short-term interval timing

    Science.gov (United States)

    Späti, Jakub; Aritake, Sayaka; Meyer, Andrea H.; Kitamura, Shingo; Hida, Akiko; Higuchi, Shigekazu; Moriguchi, Yoshiya; Mishima, Kazuo

    2015-01-01

    Short-term interval timing i.e., perception and action relating to durations in the seconds range, has been suggested to display time-of-day as well as wake dependent fluctuations due to circadian and sleep-homeostatic changes to the rate at which an underlying pacemaker emits pulses; pertinent human data being relatively sparse and lacking in consistency however, the phenomenon remains elusive and its mechanism poorly understood. To better characterize the putative circadian and sleep-homeostatic effects on interval timing and to assess the ability of a pacemaker-based mechanism to account for the data, we measured timing performance in eighteen young healthy male subjects across two epochs of sustained wakefulness of 38.67 h each, conducted prior to (under entrained conditions) and following (under free-running conditions) a 28 h sleep-wake schedule, using the methods of duration estimation and duration production on target intervals of 10 and 40 s. Our findings of opposing oscillatory time courses across both epochs of sustained wakefulness that combine with increasing and, respectively, decreasing, saturating exponential change for the tasks of estimation and production are consistent with the hypothesis that a pacemaker emitting pulses at a rate controlled by the circadian oscillator and increasing with time awake determines human short-term interval timing; the duration-specificity of this pattern is interpreted as reflecting challenges to maintaining stable attention to the task that progressively increase with stimulus magnitude and thereby moderate the effects of pacemaker-rate changes on overt behavior. PMID:25741253

  13. Metamaterials with Gain

    Science.gov (United States)

    Hess, Ortwin

    2012-02-01

    Nanoplasmonic metamaterials are the key to an extreme control of light and allow us to conceive materials with negative or vanishing refractive index. Indeed, metamaterials enable a multitude of exciting and useful applications, such as subwavelength focusing, invisibility cloaking, and ``trapped rainbow'' stopping of light. The realization of these materials has recently advanced from the microwave to the optical regime. However, at optical wavelengths, metamaterials may suffer from high dissipative losses owing to the metallic nature of their constituent nanoplasmonic meta-molecules. It is therefore not surprising that overcoming loss restrictions by gain is currently one of the most important topics in metamaterials' research. At the same time, providing gain on the nanoplasmonic (metamolecular) level opens up exciting new possibilities such as a whole new type of metamaterial nano-laser with a cavity length of about a tenth of the wavelength. The talk gives an overview of the state of the art of gain-enhanced metamaterials. Particular focus will be placed on nano-plasmonic metamaterials (such as double-fishnet metamaterials) with integrated laser dyes as gain medium. The successful compensation of loss by gain is demonstrated on the meta-molecular level. On the basis of a comprehensive, microscopic Maxwell-Bloch Langevin approach of spatio-temporal light amplification and lasing in gain-enhanced nanoplasmonic (negative-index) metamaterials a methodology based on the discrete Poynting's theorem is introduced that allows dynamic tracing of the flow of electromagnetic energy into and out of ``microscopic'' channels (light field, plasmons, gain medium). It is shown that steady-state amplification can be achieved in nanoplasmonic metamaterials. Finally, a complex spatio-temporal interplay of light-field and coherent absorption dynamics is revealed in the lasing dynamics of a nanoplasmonic gain-enhanced double-fishnet metamaterial.

  14. Gain Flattening Filter Canceling Temperature Dependence of EDFA s gain

    Institute of Scientific and Technical Information of China (English)

    M.; Ohmura; Y.; Ishizawa; H.; Nakaji; K.; Hashimoto; T.; Shibata; M.; Shigehara; A.; Inoue

    2003-01-01

    We have developed a gain flattening filter (GFF) for an erbium doped fiber (EDF) without temperature control systems. This GFF, which consists of temperature-sensitive long period gratings (LPGs) and a temperature compensated slanted fiber Bragg grating (SFBG), follows the gain shift of EDF with temperature. Gain variation of the EDFA less than 0.25dBp-p was achieved with the bandwidth of 37nm, and the temperature range 0-65℃ without any temperature control systems.

  15. Homeostatic maintenance of ponderosa pine gas exchange in response to stand density changes.

    Science.gov (United States)

    McDowell, Nate G; Adams, Henry D; Bailey, John D; Hess, Marcey; Kolb, Thomas E

    2006-06-01

    Homeostatic maintenance of gas exchange optimizes carbon gain per water loss. Homeostasis is regulated by short-term physiological and long-term structural mechanisms, both of which may respond to changes in resource availability associated with competition. Therefore, stand density regulation via silvicultural manipulations may facilitate growth and survival through mechanisms operating at both short and long timescales. We investigated the responses of ponderosa pine (Pinus ponderosa) to stand basal area manipulations in Arizona, USA. Stand basal area was manipulated to seven replicated levels in 1962 and was maintained for four decades by decadal thinning. We measured basal area increment (BAI) to assess the response and sustainability of wood growth, carbon isotope discrimination (A) inferred from annual rings to assess the response of crown gas exchange, and ratios of leaf area to sapwood area (A(l):A(s)) to assess longer term structural acclimation. Basal area treatments increased soil water potential (r2 = 0.99) but did not affect photosynthetic capacity. BAI increased within two years of thinning, and the 40-year mean BAI was negatively correlated with stand basal area (r2 = 0.98). delta was negatively correlated with stand basal area for years 5 through 12 after thinning (r2 = 0.90). However, delta was relatively invariant with basal area for the period 13-40 years after initial thinning despite maintenance of treatment basal areas via repeated decadal thinnings. Independent gas exchange measurements verified that the ratio of photosynthesis to stomatal conductance was invariant with basal area, but absolute values of both were elevated at lower basal areas. A(l):A(s) was negatively correlated with basal area (r2 = 0.93). We hypothesize that increased A(l):A(s) is a homeostatic response to increased water availability that maximizes water-use efficiency and whole-tree carbon uptake. Elevated A(l):A(s) of trees at low basal areas was associated with greater

  16. Gaining control: changing relations between executive control and processing speed and their relevance for mathematics achievement over course of the preschool period.

    Science.gov (United States)

    Clark, Caron A C; Nelson, Jennifer Mize; Garza, John; Sheffield, Tiffany D; Wiebe, Sandra A; Espy, Kimberly Andrews

    2014-01-01

    Early executive control (EC) predicts a range of academic outcomes and shows particularly strong associations with children's mathematics achievement. Nonetheless, a major challenge for EC research lies in distinguishing EC from related cognitive constructs that also are linked to achievement outcomes. Developmental cascade models suggest that children's information processing speed is a driving mechanism in cognitive development that supports gains in working memory, inhibitory control and associated cognitive abilities. Accordingly, individual differences in early executive task performance and their relation to mathematics may reflect, at least in part, underlying variation in children's processing speed. The aims of this study were to: (1) examine the degree of overlap between EC and processing speed at different preschool age points; and (2) determine whether EC uniquely predicts children's mathematics achievement after accounting for individual differences in processing speed. As part of a longitudinal, cohort-sequential study, 388 children (50% boys; 44% from low income households) completed the same battery of EC tasks at ages 3, 3.75, 4.5, and 5.25 years. Several of the tasks incorporated baseline speeded naming conditions with minimal EC demands. Multidimensional latent models were used to isolate the variance in executive task performance that did not overlap with baseline processing speed, covarying for child language proficiency. Models for separate age points showed that, while EC did not form a coherent latent factor independent of processing speed at age 3 years, it did emerge as a distinct factor by age 5.25. Although EC at age 3 showed no distinct relation with mathematics achievement independent of processing speed, EC at ages 3.75, 4.5, and 5.25 showed independent, prospective links with mathematics achievement. Findings suggest that EC and processing speed are tightly intertwined in early childhood. As EC becomes progressively decoupled from

  17. Sleep Patterns and Homeostatic Mechanisms in Adolescent Mice

    Directory of Open Access Journals (Sweden)

    Giulio Tononi

    2013-03-01

    Full Text Available Sleep changes were studied in mice (n = 59 from early adolescence to adulthood (postnatal days P19–111. REM sleep declined steeply in early adolescence, while total sleep remained constant and NREM sleep increased slightly. Four hours of sleep deprivation starting at light onset were performed from ages P26 through adulthood (>P60. Following this acute sleep deprivation all mice slept longer and with more consolidated sleep bouts, while NREM slow wave activity (SWA showed high interindividual variability in the younger groups, and increased consistently only after P42. Three parameters together explained up to 67% of the variance in SWA rebound in frontal cortex, including weight-adjusted age and increase in alpha power during sleep deprivation, both of which positively correlated with the SWA response. The third, and strongest predictor was the SWA decline during the light phase in baseline: mice with high peak SWA at light onset, resulting in a large SWA decline, were more likely to show no SWA rebound after sleep deprivation, a result that was also confirmed in parietal cortex. During baseline, however, SWA showed the same homeostatic changes in adolescents and adults, declining in the course of sleep and increasing across periods of spontaneous wake. Thus, we hypothesize that, in young adolescent mice, a ceiling effect and not the immaturity of the cellular mechanisms underlying sleep homeostasis may prevent the SWA rebound when wake is extended beyond its physiological duration.

  18. Molecular substrates of schizophrenia: homeostatic signaling to connectivity.

    Science.gov (United States)

    Landek-Salgado, M A; Faust, T E; Sawa, A

    2016-01-01

    Schizophrenia (SZ) is a devastating psychiatric condition affecting numerous brain systems. Recent studies have identified genetic factors that confer an increased risk of SZ and participate in the disease etiopathogenesis. In parallel to such bottom-up approaches, other studies have extensively reported biological changes in patients by brain imaging, neurochemical and pharmacological approaches. This review highlights the molecular substrates identified through studies with SZ patients, namely those using top-down approaches, while also referring to the fruitful outcomes of recent genetic studies. We have subclassified the molecular substrates by system, focusing on elements of neurotransmission, targets in white matter-associated connectivity, immune/inflammatory and oxidative stress-related substrates, and molecules in endocrine and metabolic cascades. We further touch on cross-talk among these systems and comment on the utility of animal models in charting the developmental progression and interaction of these substrates. Based on this comprehensive information, we propose a framework for SZ research based on the hypothesis of an imbalance in homeostatic signaling from immune/inflammatory, oxidative stress, endocrine and metabolic cascades that, at least in part, underlies deficits in neural connectivity relevant to SZ. Thus, this review aims to provide information that is translationally useful and complementary to pathogenic hypotheses that have emerged from genetic studies. Based on such advances in SZ research, it is highly expected that we will discover biomarkers that may help in the early intervention, diagnosis or treatment of SZ.

  19. Endothelial Jagged-1 Is Necessary for Homeostatic and Regenerative Hematopoiesis

    Directory of Open Access Journals (Sweden)

    Michael G. Poulos

    2013-09-01

    Full Text Available The bone marrow (BM microenvironment is composed of multiple niche cells that, by producing paracrine factors, maintain and regenerate the hematopoietic stem cell (HSC pool (Morrison and Spradling, 2008. We have previously demonstrated that endothelial cells support the proper regeneration of the hematopoietic system following myeloablation (Butler et al., 2010; Hooper et al., 2009; Kobayashi et al., 2010. Here, we demonstrate that expression of the angiocrine factor Jagged-1, supplied by the BM vascular niche, regulates homeostatic and regenerative hematopoiesis through a Notch-dependent mechanism. Conditional deletion of Jagged-1 in endothelial cells (Jag1(ECKO mice results in a profound decrease in hematopoiesis and premature exhaustion of the adult HSC pool, whereas quantification and functional assays demonstrate that loss of Jagged-1 does not perturb vascular or mesenchymal compartments. Taken together, these data demonstrate that the instructive function of endothelial-specific Jagged-1 is required to support the self-renewal and regenerative capacity of HSCs in the adult BM vascular niche.

  20. A Randomized, Double-Blind, Placebo-Controlled Pilot Study of Betahistine to Counteract Olanzapine-Associated Weight Gain.

    Science.gov (United States)

    Barak, Nir; Beck, Yaffa; Albeck, Joseph H

    2016-06-01

    Patients with schizophrenia experience higher rates of obesity and related morbidity and mortality than the general population does. Given preclinical studies revealing the role of histamine H1 receptor in human eating behavior, and the potential of olanzapine to block with this system, we hypothesized that histamine H1 receptor agonists may be beneficial in reducing antipsychotic-associated weight gain. In the present study, 36 patients with a diagnosis of schizophrenia or schizoaffective disorder and treated with olanzapine were randomized to betahistine (48 mg/d) or matching placebo for 16 weeks. Study outcomes were change in body weight from baseline and effect on antipsychotic efficacy of olanzapine. The patients in the betahistine group had less weight gain (-1.95 kg) compared with placebo group (5.6 + 5.5 kg vs 6.9 + 5.6 kg, respectively). Positive and Negative Syndrome Scale Questionnaire showed improvement within each group and that subjects treated with betahistine enjoyed an improvement (reduction) by a mean of 35.7 points, higher when compared with placebo subjects who had a reduction of 26.6 points (P = 0.233). An almost equal amount of subjects in both groups experienced adverse effects during the course of this study (87.5% of betahistine vs 85.0% of placebo-treated subjects). Overall, there were no clinically marked differences in safety signals between both groups. A larger study addressing the weaknesses of this pilot study is warranted.

  1. High performance polarization-independent Quantum Dot Semiconductor Optical Amplifier with 22 dB fiber to fiber gain using Mode Propagation Tuning without additional polarization controller

    Science.gov (United States)

    Farmani, Ali; Farhang, Mahmoud; Sheikhi, Mohammad H.

    2017-08-01

    A detailed numerical investigation of polarization-independent quantum dot InAs/GaAs semiconductor optical amplifier (PIQS) based on a technique called mode propagation tuning (MPT) without the need for the polarization controller (PC) is reported, which can solve the limitation caused by polarization sensitivity in a semiconductor optical amplifier (SOA). Our calculations show that by a suitable tuning of the thickness of the active layer, only the TE0 and TM0 modes can propagate. Moreover, the gain saturation behavior of this SOA was measured at 1.55 μ m and found to be polarization-independent (PI). At active layer thickness of 1.7 μ m, the confinement factor was 0.75 and 0.7 for TE0 and TM0 modes, respectively, which leads to a gain difference up to 0.1 dB. The rate equations of the QD-SOA were also solved and a fiber to fiber gain of 22 dB was obtained. Additionally, a numerical simulation is presented which shows that the residual gain ripple and polarization sensitivity are sufficiently reduced when residual facet reflectivities of the SOA are in the range below 10-4 . In addition, the full-width at half-maximum of the horizontal and vertical far-field patterns (FFPs) are measured as 30° × 30°. The proposed structure can be used for logical applications.

  2. Controlling inbreeding and maximizing genetic gain using semi-definite programming with pedigree-based and genomic relationships.

    Science.gov (United States)

    Schierenbeck, S; Pimentel, E C G; Tietze, M; Körte, J; Reents, R; Reinhardt, F; Simianer, H; König, S

    2011-12-01

    Because of the relatively high levels of genetic relationships among potential bull sires and bull dams, innovative selection tools should consider both genetic gain and genetic relationships in a long-term perspective. Optimum genetic contribution theory using official estimated breeding values for a moderately heritable trait (production index, Index-PROD), and a lowly heritable functional trait (index for somatic cell score, Index-SCS) was applied to find optimal allocations of bull dams and bull sires. In contrast to previous practical applications using optimizations based on Lagrange multipliers, we focused on semi-definite programming (SDP). The SDP methodology was combined with either pedigree (a(ij)) or genomic relationships (f(ij)) among selection candidates. Selection candidates were 484 genotyped bulls, and 499 preselected genotyped bull dams completing a central test on station. In different scenarios separately for PROD and SCS, constraints on the average pedigree relationships among future progeny were varied from a(ij)=0.08 to a(ij)=0.20 in increments of 0.01. Corresponding constraints for single nucleotide polymorphism-based kinship coefficients were derived from regression analysis. Applying the coefficient of 0.52 with an intercept of 0.14 estimated for the regression pedigree relationship on genomic relationship, the corresponding range to alter genomic relationships varied from f(ij) = 0.18 to f(ij) = 0.24. Despite differences for some bulls in genomic and pedigree relationships, the same trends were observed for constraints on pedigree and corresponding genomic relationships regarding results in genetic gain and achieved coefficients of relationships. Generally, allowing higher values for relationships resulted in an increase of genetic gain for Index-PROD and Index-SCS and in a reduction in the number of selected sires. Interestingly, more sires were selected for all scenarios when restricting genomic relationships compared with restricting

  3. MYB-FL controls gain and loss of floral UV absorbance, a key trait affecting pollinator preference and reproductive isolation.

    Science.gov (United States)

    Sheehan, Hester; Moser, Michel; Klahre, Ulrich; Esfeld, Korinna; Dell'Olivo, Alexandre; Mandel, Therese; Metzger, Sabine; Vandenbussche, Michiel; Freitas, Loreta; Kuhlemeier, Cris

    2016-02-01

    Adaptations to new pollinators involve multiple floral traits, each requiring coordinated changes in multiple genes. Despite this genetic complexity, shifts in pollination syndromes have happened frequently during angiosperm evolution. Here we study the genetic basis of floral UV absorbance, a key trait for attracting nocturnal pollinators. In Petunia, mutations in a single gene, MYB-FL, explain two transitions in UV absorbance. A gain of UV absorbance in the transition from bee to moth pollination was determined by a cis-regulatory mutation, whereas a frameshift mutation caused subsequent loss of UV absorbance during the transition from moth to hummingbird pollination. The functional differences in MYB-FL provide insight into the process of speciation and clarify phylogenetic relationships between nascent species.

  4. Time course of the induction of homeostatic plasticity generated by repeated transcranial direct current stimulation of the human motor cortex.

    Science.gov (United States)

    Fricke, K; Seeber, A A; Thirugnanasambandam, N; Paulus, W; Nitsche, M A; Rothwell, J C

    2011-03-01

    Several mechanisms have been proposed that control the amount of plasticity in neuronal circuits and guarantee dynamic stability of neuronal networks. Homeostatic plasticity suggests that the ease with which a synaptic connection is facilitated/suppressed depends on the previous amount of network activity. We describe how such homeostatic-like interactions depend on the time interval between two conditioning protocols and on the duration of the preconditioning protocol. We used transcranial direct current stimulation (tDCS) to produce short-lasting plasticity in the motor cortex of healthy humans. In the main experiment, we compared the aftereffect of a single 5-min session of anodal or cathodal tDCS with the effect of a 5-min tDCS session preceded by an identical 5-min conditioning session administered 30, 3, or 0 min beforehand. Five-minute anodal tDCS increases excitability for about 5 min. The same duration of cathodal tDCS reduces excitability. Increasing the duration of tDCS to 10 min prolongs the duration of the effects. If two 5-min periods of tDCS are applied with a 30-min break between them, the effect of the second period of tDCS is identical to that of 5-min stimulation alone. If the break is only 3 min, then the second session has the opposite effect to 5-min tDCS given alone. Control experiments show that these shifts in the direction of plasticity evolve during the 10 min after the first tDCS session and depend on the duration of the first tDCS but not on intracortical inhibition and facilitation. The results are compatible with a time-dependent "homeostatic-like" rule governing the response of the human motor cortex to plasticity probing protocols.

  5. Homeostatic capabilities of the choroid plexus epithelium in Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Duncan John

    2004-12-01

    Full Text Available Abstract As the secretory source of vitamins, peptides and hormones for neurons, the choroid plexus (CP epithelium critically provides substances for brain homeostasis. This distributive process of cerebrospinal fluid (CSF volume transmission reaches many cellular targets in the CNS. In ageing and ageing-related dementias, the CP-CSF system is less able to regulate brain interstitial fluid. CP primarily generates CSF bulk flow, and so its malfunctioning exacerbates Alzheimers disease (AD. Considerable attention has been devoted to the blood-brain barrier in AD, but more insight is needed on regulatory systems at the human blood-CSF barrier in order to improve epithelial function in severe disease. Using autopsied CP specimens from AD patients, we immunocytochemically examined expression of heat shock proteins (HSP90 and GRP94, fibroblast growth factor receptors (FGFr and a fluid-regulatory protein (NaK2Cl cotransporter isoform 1 or NKCC1. CP upregulated HSP90, FGFr and NKCC1, even in end-stage AD. These CP adjustments involve growth factors and neuropeptides that help to buffer perturbations in CNS water balance and metabolism. They shed light on CP-CSF system responses to ventriculomegaly and the altered intracranial pressure that occurs in AD and normal pressure hydrocephalus. The ability of injured CP to express key regulatory proteins even at Braak stage V/VI, points to plasticity and function that may be boosted by drug treatment to expedite CSF dynamics. The enhanced expression of human CP 'homeostatic proteins' in AD dementia is discussed in relation to brain deficits and pharmacology.

  6. Arc/Arg3.1 Mediates Homeostatic Synaptic Scaling of AMPA Receptors

    National Research Council Canada - National Science Library

    Shepherd, Jason D; Rumbaugh, Gavin; Wu, Jing; Chowdhury, Shoaib; Plath, Niels; Kuhl, Dietmar; Huganir, Richard L; Worley, Paul F

    2006-01-01

    .... Here, we demonstrate that Arc/Arg3.1, an immediate-early gene (IEG) that is rapidly induced by neuronal activity associated with information encoding in the brain, mediates homeostatic synaptic scaling of AMPA type glutamate receptors (AMPARs...

  7. 零相差跟踪控制器增益特性处理技术%Gain-characteristics manipulation technique for zero phase error tracking controller

    Institute of Scientific and Technical Information of China (English)

    周黎; 杨世洪; 高晓东

    2012-01-01

    In a zero phase error tracking control system, the gain error increases as frequency increases; meanwhile, the zero phase error tracking control system exhibits amplification to high frequency noises. In order to solve these problems, a gain-characteristics manipulation method for zero phase error tracking controller is investigated based on the idea of op- timization. By setting the optimization objective function and restriction conditions, we design the gain error compensator with gain-compensation in low frequency band and gain-attenuation in high frequency band. The design process is given in details and the parameter calculation formulas are derived analytically. Simulation results indicate that the designed compensator effectively increases the tracking accuracy and reduces noise content in controller output, thus, improving the motion smoothness and providing advantages for engineering applications.%零相差跟踪控制系统增益误差随频率升高而增大,同时零相差跟踪控制器对高频噪声有放大作用.为了解决以上问题,本文研究了一种对零相差跟踪控制器增益特性的处理方法.采用了求解优化问题的思想,通过对优化目标函数及约束条件的设置,使设计得到的补偿器具有低频段增益误差补偿,高频段增益衰减的性能.文中详细介绍了补偿器的设计过程,理论推导了参数计算公式.比较仿真结果表明,所设计的补偿器有效地提高了轨迹跟踪精度,减小了控制器输出噪声含量,有利于提高运动平稳性,对工程实践具有参考价值.

  8. Application of matrix singular value properties for evaluating gain and phase margins of multiloop systems. [stability margins for wing flutter suppression and drone lateral attitude control

    Science.gov (United States)

    Mukhopadhyay, V.; Newsom, J. R.

    1982-01-01

    A stability margin evaluation method in terms of simultaneous gain and phase changes in all loops of a multiloop system is presented. A universal gain-phase margin evaluation diagram is constructed by generalizing an existing method using matrix singular value properties. Using this diagram and computing the minimum singular value of the system return difference matrix over the operating frequency range, regions of guaranteed stability margins can be obtained. Singular values are computed for a wing flutter suppression and a drone lateral attitude control problem. The numerical results indicate that this method predicts quite conservative stability margins. In the second example if the eigenvalue magnitude is used instead of the singular value, as a measure of nearness to singularity, more realistic stability margins are obtained. However, this relaxed measure generally cannot guarantee global stability.

  9. Application of matrix singular value properties for evaluating gain and phase margins of multiloop systems. [stability margins for wing flutter suppression and drone lateral attitude control

    Science.gov (United States)

    Mukhopadhyay, V.; Newsom, J. R.

    1982-01-01

    A stability margin evaluation method in terms of simultaneous gain and phase changes in all loops of a multiloop system is presented. A universal gain-phase margin evaluation diagram is constructed by generalizing an existing method using matrix singular value properties. Using this diagram and computing the minimum singular value of the system return difference matrix over the operating frequency range, regions of guaranteed stability margins can be obtained. Singular values are computed for a wing flutter suppression and a drone lateral attitude control problem. The numerical results indicate that this method predicts quite conservative stability margins. In the second example if the eigenvalue magnitude is used instead of the singular value, as a measure of nearness to singularity, more realistic stability margins are obtained. However, this relaxed measure generally cannot guarantee global stability.

  10. Homeostatic and Circadian Abnormalities in Sleep and Arousal in Gulf War Syndrome

    Science.gov (United States)

    2015-10-01

    areas would have deleterious impacts on short-term daytime function. Moreover, optimal sleep is not only critical for daytime learning and...1 Award Number: W81XWH-10-2-0129 TITLE: Homeostatic and Circadian Abnormalities in Sleep and Arousal in Gulf War Syndrome PRINCIPAL INVESTIGATOR...To) 4. TITLE AND SUBTITLE in Gul 5a. CONTRACT NUMBER W81XWH-10-2-0129 Homeostatic and Circadian Abnormalities in Sleep and Arousal f War Syndrome 5b

  11. Simultaneous gains tuning in boiler/turbine PID-based controller clusters using iterative feedback tuning methodology.

    Science.gov (United States)

    Zhang, Shu; Taft, Cyrus W; Bentsman, Joseph; Hussey, Aaron; Petrus, Bryan

    2012-09-01

    Tuning a complex multi-loop PID based control system requires considerable experience. In today's power industry the number of available qualified tuners is dwindling and there is a great need for better tuning tools to maintain and improve the performance of complex multivariable processes. Multi-loop PID tuning is the procedure for the online tuning of a cluster of PID controllers operating in a closed loop with a multivariable process. This paper presents the first application of the simultaneous tuning technique to the multi-input-multi-output (MIMO) PID based nonlinear controller in the power plant control context, with the closed-loop system consisting of a MIMO nonlinear boiler/turbine model and a nonlinear cluster of six PID-type controllers. Although simplified, the dynamics and cross-coupling of the process and the PID cluster are similar to those used in a real power plant. The particular technique selected, iterative feedback tuning (IFT), utilizes the linearized version of the PID cluster for signal conditioning, but the data collection and tuning is carried out on the full nonlinear closed-loop system. Based on the figure of merit for the control system performance, the IFT is shown to deliver performance favorably comparable to that attained through the empirical tuning carried out by an experienced control engineer.

  12. Parental Body Mass Index, Gestational Weight Gain, and Risk of Macrosomia: a Population-Based Case-Control Study in China.

    Science.gov (United States)

    Yang, Shaoping; Zhou, Aifen; Xiong, Chao; Yang, Rong; Bassig, Bryan A; Hu, Ronghua; Zhang, Yiming; Yao, Cong; Zhang, Yaqi; Qiu, Lin; Qian, Zhengmin; Trevathan, Edwin; Flick, Louise; Xu, Shunqing; Wang, Youjie; Xia, Wei; Zheng, Tongzhang; Zhang, Bin

    2015-09-01

    The prevalence of macrosomia has risen markedly worldwide, including in China, during the past two decades. Few epidemiological studies, however, have investigated the risk factors for macrosomia in China. This study was designed to investigate the associations between parental anthropometric characteristics, gestational weight gain (GWG), and risk of macrosomia in China. This population-based, case-control study in Wuhan, China, included a total of 6341 subjects (870 cases and 5471 controls). Multivariable logistic regression was conducted to calculate odds ratios (OR) and 95% confidence intervals (CI). Mothers or fathers who were overweight or obese before pregnancy had an elevated risk of giving birth to a macrosomic infant compared with their normal weight counterparts. Women with GWG above the Institute of Medicine (IOM) recommendation had an adjusted OR of 6.09 [95% CI 5.04, 7.35] for delivering a macrosomic infant compared with women who had GWG within the IOM recommendation. When stratified by maternal pre-pregnancy body mass index (BMI), women who were underweight or normal weight before pregnancy were observed to have a higher risk of macrosomia birth associated with greater GWG. Parental pre-pregnancy overweight/obesity and excessive GWG during pregnancy were highly associated with macrosomia. The association with GWG was most pronounced in mothers who had a normal or underweight pre-pregnancy BMI. Weight control efforts before pregnancy for mothers and fathers as well as control of maternal gain during pregnancy may reduce the risk of macrosomia. © 2015 John Wiley & Sons Ltd.

  13. Neuronal systems and circuits involved in the control of food intake and adaptive thermogenesis.

    Science.gov (United States)

    Caron, Alexandre; Richard, Denis

    2017-03-01

    With the still-growing prevalence of obesity worldwide, major efforts are made to understand the various behavioral, environmental, and genetic factors that promote excess fat gain. Obesity results from an imbalance between energy intake and energy expenditure, which emphasizes the importance of deciphering the mechanisms behind energy balance regulation to understand its physiopathology. The control of energy balance is assured by brain systems/circuits capable of generating adequate ingestive and thermogenic responses to maintain the stability of energy reserves, which implies a proper integration of the homeostatic signals that inform about the status of the energy stores. In this article, we overview the organization and functionality of key neuronal circuits or pathways involved in the control of food intake and energy expenditure. We review the role of the corticolimbic (executive and reward) and autonomic systems that integrate their activities to regulate energy balance. We also describe the mechanisms and pathways whereby homeostatic sensing is achieved in response to variations of homeostatic hormones, such as leptin, insulin, and ghrelin, while putting some emphasis on the prominent importance of the mechanistic target of the rapamycin signaling pathway in coordinating the homeostatic sensing process. © 2016 New York Academy of Sciences.

  14. Pupil diameter tracks changes in control state predicted by the adaptive gain theory of locus coeruleus function.

    Science.gov (United States)

    Gilzenrat, Mark S; Nieuwenhuis, Sander; Jepma, Marieke; Cohen, Jonathan D

    2010-05-01

    An important dimension of cognitive control is the adaptive regulation of the balance between exploitation (pursuing known sources of reward) and exploration (seeking new ones) in response to changes in task utility. Recent studies have suggested that the locus coeruleus-norepinephrine system may play an important role in this function and that pupil diameter can be used to index locus coeruleus activity. On the basis of this, we reasoned that pupil diameter may correlate closely with control state and associated changes in behavior. Specifically, we predicted that increases in baseline pupil diameter would be associated with decreases in task utility and disengagement from the task (exploration), whereas reduced baseline diameter (but increases in task-evoked dilations) would be associated with task engagement (exploitation). Findings in three experiments were consistent with these predictions, suggesting that pupillometry may be useful as an index of both control state and, indirectly, locus coeruleus function.

  15. Dt2 is a gain-of-function MADS-Domain factor gene that controls semi-determinacy in soybean

    Science.gov (United States)

    Similar to Arabidopsis, the wild soybean (Glycine soja) and many soybean (Glycine max) cultivars exhibit indeterminate stem growth controlled by a gene Dt1 – the functional counterpart of the Arabidopsis TFL1. Mutations in TFL1 and Dt1 both result in the shoot apical meristem (SAM) switching from ve...

  16. Design and Implementation of Adaptive Model Based Gain Scheduled Controller for a Real Time Non Linear System in LabVIEW

    Directory of Open Access Journals (Sweden)

    M. Kalyan Chakravarthi

    2015-05-01

    Full Text Available The aim of this study is to design and implement an Adaptive Model Based Gain Scheduled (AMBGS Controller using classical controller tuning techniques for a Single Spherical Nonlinear Tank System (SSTLLS. A varying range of development in the control mechanisms have been evidently seen in the last two decades. The control of level has always been a topic of discussion in the process control scenario. In this study a real time SSTLLS has been chosen for investigation. System identification of these different regions of nonlinear process is done using black box model, which is identified to be nonlinear and approximated to be a First Order plus Dead Time (FOPDT model. A proportional and integral controller is designed using LabVIEW and Skogestad’s and Ziegler Nichols (ZN tuning methods are implemented. The paper will provide details about the data acquisition unit, shows the implementation of the controller and compare the results of PI tuning methods used for an AMBGS Controller.

  17. Gaining Control over Radiolytic Synthesis of Uniform Sub-3-nanometer Palladium Nanoparticles: Use of Aromatic Liquids in the Electron Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Abellan Baeza, Patricia; Parent, Lucas R.; Al Hasan, Naila M.; Park, Chiwoo; Arslan, Ilke; Karim, Ayman M.; Evans, James E.; Browning, Nigel D.

    2016-01-07

    Synthesizing nanomaterials of uniform shape and size is of critical importance to access and manipulate the novel structure-property relationships arising at the nanoscale. In this work we synthesize Pd nanoparticles with well-controlled size using in situ liquid-stage scanning transmission electron microscopy (STEM) and demonstrate a match between the reaction kinetics and products of the radiolytic and chemical syntheses of size-stabilized Pd nanoparticles. We quantify the effect of electron dose on the nucleation kinetics, and compare these results with in situ small angle X-ray scattering (SAXS) experiments investigating the effect of temperature during chemical synthesis. This work introduces methods for precise control of nanoparticle synthesis in the STEM and provides a means to uncover the fundamental processes behind the size and shape stabilization of nanoparticles.

  18. More gain less pain: balance control learning shifts the activation patterns of leg and neck muscles and increases muscular parsimony.

    Science.gov (United States)

    Iodice, Pierpaolo; Cesinaro, Stefano; Romani, Gian Luca; Pezzulo, Giovanni

    2015-07-01

    Athletes such as skaters or surfers maintain their balance on very unstable platforms. Remarkably, the most skilled athletes seem to execute these feats almost effortlessly. However, the dynamics that lead to the acquisition of a defined and efficient postural strategy are incompletely known. To understand the posture reorganization process due to learning and expertise, we trained twelve participants in a demanding balance/posture maintenance task for 4 months and measured their muscular activity before and after a (predictable) disturbance cued by an auditory signal. The balance training determined significant delays in the latency of participants' muscular activity: from largely anticipatory muscular activity (prior to training) to a mixed anticipatory-compensatory control strategy (after training). After training, the onset of activation was delayed for all muscles, and the sequence of activation systematically reflected the muscle position in the body from top to bottom: neck/upper body muscles were recruited first and in an anticipatory fashion, whereas leg muscles were recruited after the disturbance onset, producing compensatory adjustments. The resulting control strategy includes a mixture of anticipatory and compensatory postural adjustments, with a systematic sequence of muscular activation reflecting the different demands of neck and leg muscles. Our results suggest that subjects learned the precise timing of the disturbance onset and used this information to deploy postural adjustments just-in-time and to transfer at least part of the control of posture from anticipatory to less-demanding feedback-based strategies. In turn, this strategy shift increases the cost-efficiency of muscular activity, which is a key signature of skilled performance.

  19. Gaining Control over Radiolytic Synthesis of Uniform Sub-3-nanometer Palladium Nanoparticles: Use of Aromatic Liquids in the Electron Microscope.

    Science.gov (United States)

    Abellan, Patricia; Parent, Lucas R; Al Hasan, Naila; Park, Chiwoo; Arslan, Ilke; Karim, Ayman M; Evans, James E; Browning, Nigel D

    2016-02-16

    Synthesizing nanomaterials of uniform shape and size is of critical importance to access and manipulate the novel structure-property relationships arising at the nanoscale, such as catalytic activity. In this work, we synthesize Pd nanoparticles with well-controlled size in the sub-3 nm range using scanning transmission electron microscopy (STEM) in combination with an in situ liquid stage. We use an aromatic hydrocarbon (toluene) as a solvent that is very resistant to high-energy electron irradiation, which creates a net reducing environment without the need for additives to scavenge oxidizing radicals. The primary reducing species is molecular hydrogen, which is a widely used reductant in the synthesis of supported metal catalysts. We propose a mechanism of particle formation based on the effect of tri-n-octylphosphine (TOP) on size stabilization, relatively low production of radicals, and autocatalytic reduction of Pd(II) compounds. We combine in situ STEM results with insights from in situ small-angle X-ray scattering (SAXS) from alcohol-based synthesis, having similar reduction potential, in a customized microfluidic device as well as ex situ bulk experiments. This has allowed us to develop a fundamental growth model for the synthesis of size-stabilized Pd nanoparticles and demonstrate the utility of correlating different in situ and ex situ characterization techniques to understand, and ultimately control, metal nanostructure synthesis.

  20. To Fear Is to Gain? The Role of Fear Recognition in Risky Decision Making in TBI Patients and Healthy Controls

    Science.gov (United States)

    Visser-Keizer, Annemarie C.; Westerhof-Evers, Herma J.; Gerritsen, Marleen J. J.; van der Naalt, Joukje; Spikman, Jacoba M.

    2016-01-01

    Fear is an important emotional reaction that guides decision making in situations of ambiguity or uncertainty. Both recognition of facial expressions of fear and decision making ability can be impaired after traumatic brain injury (TBI), in particular when the frontal lobe is damaged. So far, it has not been investigated how recognition of fear influences risk behavior in healthy subjects and TBI patients. The ability to recognize fear is thought to be related to the ability to experience fear and to use it as a warning signal to guide decision making. We hypothesized that a better ability to recognize fear would be related to a better regulation of risk behavior, with healthy controls outperforming TBI patients. To investigate this, 59 healthy subjects and 49 TBI patients were assessed with a test for emotion recognition (Facial Expression of Emotion: Stimuli and Tests) and a gambling task (Iowa Gambling Task (IGT)). The results showed that, regardless of post traumatic amnesia duration or the presence of frontal lesions, patients were more impaired than healthy controls on both fear recognition and decision making. In both groups, a significant relationship was found between better fear recognition, the development of an advantageous strategy across the IGT and less risk behavior in the last blocks of the IGT. Educational level moderated this relationship in the final block of the IGT. This study has important clinical implications, indicating that impaired decision making and risk behavior after TBI can be preceded by deficits in the processing of fear. PMID:27870900

  1. Muscle weakness and lack of reflex gain adaptation predominate during post-stroke posture control of the wrist

    Directory of Open Access Journals (Sweden)

    van der Helm Frans CT

    2009-07-01

    Full Text Available Abstract Background Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to wrist joint stiffness during an active posture task. Methods Continuous random torque perturbations applied to the wrist joint by a haptic manipulator had to be resisted maximally. Reflex provoking conditions were applied i.e. additional viscous loads and reduced perturbation signal bandwidth. Linear system identification and neuromuscular modeling were used to separate joint stiffness into the intrinsic resistance of the muscles including co-contraction and the reflex mediated contribution. Results Compared to an age and sex matched control group, patients showed an overall 50% drop in intrinsic elasticity while their reflexive contribution did not respond to provoking conditions. Patients showed an increased mechanical stability compared to control subjects. Conclusion Post stroke, we found active posture tasking to be dominated by: 1 muscle weakness and 2 lack of reflex adaptation. This adds to existing doubts on reflex blocking therapy as the sole paradigm to improve active task performance and draws attention to muscle strength and power recovery and the role of the inability to modulate reflexes in post stroke movement disorders.

  2. Gain Flattening Filter Canceling Temperature Dependence of EDFA's gain

    Institute of Scientific and Technical Information of China (English)

    M. Ohmura; Y. Ishizawa; H. Nakaji; K. Hashimoto; T. Shibata; M. Shigehara; A. Inoue

    2003-01-01

    We have developed a gain flattening filter(GFF) for an erbium doped fiber (EDF) without temperature control systems. This GFF, which consists of temperature-sensitive long period gratings (LPGs)and a temperature compensated slanted fiber Bragg grating (SFBG), follows the gain shift of EDF with temperature. Gain variation of the EDFA less than 0.25dBp-p was achieved with the bandwidth of 37nm,and the temperature range 0-65℃ without and temperature control systems.

  3. The dendritic cell response to classic, emerging, and homeostatic danger signals. Implications for autoimmunity.

    Science.gov (United States)

    Gallo, Paul M; Gallucci, Stefania

    2013-01-01

    Dendritic cells (DCs) initiate and control immune responses, participate in the maintenance of immunological tolerance and are pivotal players in the pathogenesis of autoimmunity. In patients with autoimmune disease and in experimental animal models of autoimmunity, DCs show abnormalities in both numbers and activation state, expressing immunogenic levels of costimulatory molecules and pro-inflammatory cytokines. Exogenous and endogenous danger signals activate DCs to stimulate the immune response. Classic endogenous danger signals are released, activated, or secreted by host cells and tissues experiencing stress, damage, and non-physiologic cell death; and are therefore referred to as damage-associated molecular patterns (DAMPs). Some DAMPs are released from cells, where they are normally sequestered, during necrosis (e.g., heat shock proteins, uric acid, ATP, HMGB1, mitochondria-derived molecules). Others are actively secreted, like Type I Interferons. Here we discuss important DAMPs in the context of autoimmunity. For some, there is a clear pathogenic link (e.g., nucleic acids and lupus). For others, there is less evidence. Additionally, we explore emerging danger signals. These include inorganic materials and man-made technologies (e.g., nanomaterials) developed as novel therapeutic approaches. Some nanomaterials can activate DCs and may trigger unintended inflammatory responses. Finally, we will review "homeostatic danger signals," danger signals that do not derive directly from pathogens or dying cells but are associated with perturbations of tissue/cell homeostasis and may signal pathological stress. These signals, like acidosis, hypoxia, and changes in osmolarity, also play a role in inflammation and autoimmunity.

  4. Imbalance of Clara cell-mediated homeostatic inflammation is involved in lung metastasis.

    Science.gov (United States)

    Tomita, T; Sakurai, Y; Ishibashi, S; Maru, Y

    2011-08-04

    We have previously shown that tumor necrosis factor (TNF)α produced from primary tumor-induced expression of two endogenous Toll-like receptor 4 (TLR4) ligands, S100A8 and serum amyloid A3 (SAA3), in pre-metastatic lungs. However, mechanistic details of the signaling network and relevance to pulmonary physiology are poorly understood. Here, we identify Clara cells as a control tower of the network. Clara cell ablation by naphthalene suppressed pulmonary recruitment of CD11b+TLR4+ cells and spontaneous lung metastasis. Clara cells turned out to express TLR4 through which SAA3 was auto-amplified. Reciprocal bone marrow transplantation between wild-type and TLR4 knockout mice demonstrated that pulmonary TLR4+ Clara cells could be derived from bone marrow. SAA3-induced TNFα expression in both alveolar type II cells and macrophages. Primary co-cultures of alveolar type II cells and Clara cells revealed that the induction of TNFα in alveolar type II cells was dependent on the Clara cell-mediated amplification of SAA3. SAA3 induction by bacterial endotoxin also required both Clara cells and TLR4. Thus, pulmonary metastatic soil may feature deregulation of homeostatic inflammatory responses to constant assaults of microbes with endotoxin.

  5. Metabolomic anatomy of an animal model revealing homeostatic imbalances in dyslipidaemia.

    Science.gov (United States)

    Ooga, Takushi; Sato, Hajime; Nagashima, Atsushi; Sasaki, Kazunori; Tomita, Masaru; Soga, Tomoyoshi; Ohashi, Yoshiaki

    2011-04-01

    Metabolomics is an emerging technology that reveals homeostatic imbalances in biological systems. Global determination of metabolite concentrations in body fluid and tissues provides novel anatomical aspects of pathological conditions that cannot be obtained from target-specific measurements. Here, we characterised metabolic imbalance in Watanabe heritable hyperlipidaemic rabbits as a model of hypercholesterolaemia. Using a mass spectrometry-based system, we measured a total of 335 metabolites in plasma and tissues (liver, aorta, cardiac muscle, and brain) from WHHL and healthy control rabbits. From the comparison between two metabolomic profiles, pathophysiological features including glutathione and phosphatidylcholine metabolism indicated the occurrence of oxidative stress in several tissues. Especially for the liver, imbalanced purine catabolism shed light on the transcriptional activation of xanthine oxidase, which is thought to act in absorbing or possibly triggering oxidative stress. We also applied this system to assess the therapeutic effects of simvastatin administration. After the treatment, a portion of the metabolomic features in pathological conditions showed alterations suggesting restoration of metabolism to the healthy condition. These changes were considered to be due to the pleiotropic action of statin, including antioxidant effects, rather than its main inhibitory action on cholesterol biosynthesis.

  6. Fuzzy Adaptive Control of Stochastic Nonlinear Systems with Unknown Virtual Control Gain Function%虚拟控制增益函数未知的随机非线性系统模糊自适应控制

    Institute of Scientific and Technical Information of China (English)

    王迎春; 张化光; 王以忠

    2006-01-01

    The problem of track control is studied for a class of strict-feedback stochastic nonlinear systems in which unknown virtual control gain function is the main feature. First, the so-called stochastic LaSalle theory is extended to some extent, and accordingly, the results of global ultimate boundedness for stochastic nonlinear systems are developed. Next, a new design scheme of fuzzy adaptive control is proposed. The advantage of it is that it does not require priori knowledge of virtual control gain function sign, which is usually demanded in many designs. At the same time,the track performance of closed-loop systems is improved by adaptive modifying the estimated error upper bound. By theoretical analysis, the signals of closed-loop systems are globally ultimately bounded in probability and the track error converges to a small residual set around the origin in 4th-power expectation.

  7. Application of multi-objective controller to optimal tuning of PID gains for a hydraulic turbine regulating system using adaptive grid particle swam optimization.

    Science.gov (United States)

    Chen, Zhihuan; Yuan, Yanbin; Yuan, Xiaohui; Huang, Yuehua; Li, Xianshan; Li, Wenwu

    2015-05-01

    A hydraulic turbine regulating system (HTRS) is one of the most important components of hydropower plant, which plays a key role in maintaining safety, stability and economical operation of hydro-electrical installations. At present, the conventional PID controller is widely applied in the HTRS system for its practicability and robustness, and the primary problem with respect to this control law is how to optimally tune the parameters, i.e. the determination of PID controller gains for satisfactory performance. In this paper, a kind of multi-objective evolutionary algorithms, named adaptive grid particle swarm optimization (AGPSO) is applied to solve the PID gains tuning problem of the HTRS system. This newly AGPSO optimized method, which differs from a traditional one-single objective optimization method, is designed to take care of settling time and overshoot level simultaneously, in which a set of non-inferior alternatives solutions (i.e. Pareto solution) is generated. Furthermore, a fuzzy-based membership value assignment method is employed to choose the best compromise solution from the obtained Pareto set. An illustrative example associated with the best compromise solution for parameter tuning of the nonlinear HTRS system is introduced to verify the feasibility and the effectiveness of the proposed AGPSO-based optimization approach, as compared with two another prominent multi-objective algorithms, i.e. Non-dominated Sorting Genetic Algorithm II (NSGAII) and Strength Pareto Evolutionary Algorithm II (SPEAII), for the quality and diversity of obtained Pareto solutions set. Consequently, simulation results show that this AGPSO optimized approach outperforms than compared methods with higher efficiency and better quality no matter whether the HTRS system works under unload or load conditions.

  8. A Cerebellar Framework for Predictive Coding and Homeostatic Regulation in Depressive Disorder.

    Science.gov (United States)

    Schutter, Dennis J L G

    2016-02-01

    Depressive disorder is associated with abnormalities in the processing of reward and punishment signals and disturbances in homeostatic regulation. These abnormalities are proposed to impair error minimization routines for reducing uncertainty. Several lines of research point towards a role of the cerebellum in reward- and punishment-related predictive coding and homeostatic regulatory function in depressive disorder. Available functional and anatomical evidence suggests that in addition to the cortico-limbic networks, the cerebellum is part of the dysfunctional brain circuit in depressive disorder as well. It is proposed that impaired cerebellar function contributes to abnormalities in predictive coding and homeostatic dysregulation in depressive disorder. Further research on the role of the cerebellum in depressive disorder may further extend our knowledge on the functional and neural mechanisms of depressive disorder and development of novel antidepressant treatments strategies targeting the cerebellum.

  9. Adherence to self-monitoring via interactive voice response technology in an eHealth intervention targeting weight gain prevention among Black women: randomized controlled trial.

    Science.gov (United States)

    Steinberg, Dori M; Levine, Erica L; Lane, Ilana; Askew, Sandy; Foley, Perry B; Puleo, Elaine; Bennett, Gary G

    2014-04-29

    eHealth interventions are effective for weight control and have the potential for broad reach. Little is known about the use of interactive voice response (IVR) technology for self-monitoring in weight control interventions, particularly among populations disproportionately affected by obesity. This analysis sought to examine patterns and predictors of IVR self-monitoring adherence and the association between adherence and weight change among low-income black women enrolled in a weight gain prevention intervention. The Shape Program was a randomized controlled trial comparing a 12-month eHealth behavioral weight gain prevention intervention to usual care among overweight and obese black women in the primary care setting. Intervention participants (n=91) used IVR technology to self-monitor behavior change goals (eg, no sugary drinks, 10,000 steps per day) via weekly IVR calls. Weight data were collected in clinic at baseline, 6, and 12 months. Self-monitoring data was stored in a study database and adherence was operationalized as the percent of weeks with a successful IVR call. Over 12 months, the average IVR completion rate was 71.6% (SD 28.1) and 52% (47/91) had an IVR completion rate ≥80%. At 12 months, IVR call completion was significantly correlated with weight loss (r =-.22; P=.04) and participants with an IVR completion rate ≥80% had significantly greater weight loss compared to those with an IVR completion rate educated participants were more likely to achieve high IVR call completion. Participants reported positive attitudes toward IVR self-monitoring. Adherence to IVR self-monitoring was high among socioeconomically disadvantaged black women enrolled in a weight gain prevention intervention. Higher adherence to IVR self-monitoring was also associated with greater weight change. IVR is an effective and useful tool to promote self-monitoring and has the potential for widespread use and long-term sustainability. Clinicaltrials.gov NCT00938535; http

  10. Gain scheduling using the Youla parameterization

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, Jakob

    1999-01-01

    Gain scheduling controllers are considered in this paper. The gain scheduling problem where the scheduling parameter vector cannot be measured directly, but needs to be estimated is considered. An estimation of the scheduling vector has been derived by using the Youla parameterization. The use...... in connection with H_inf gain scheduling controllers....

  11. Altered elemental profile as indicator of homeostatic imbalance in pathogenesis of oral submucous fibrosis.

    Science.gov (United States)

    Paul, Ranjan Rashmi; Chatterjee, Jyotirmoy; Das, Arabinda K; Cervera, M Luisa; de la Guardia, Miguel; Chaudhuri, Keya

    2002-01-01

    Oral submucous fibrosis (OSF) is a potential precancerous condition of the oral cavity and oropharynx. The etiopathogenesis of this complex precancerous condition is still obscure. In addition to deleterious oral habits, malnutrition, and possible genetic predisposition, altered bioelemental status is also likely to play an important role in its pathogenesis. The present study analyzed 68 elements by inductively coupled plasma-mass spectroscopy in oral mucosa of normal and OSF individuals and some interesting alterations in elemental profile in the diseased tissue have been noted, indicating a homeostatic imbalance. These bioelemental alterations leading to homeostatic imbalance might be considered as an important biological event in the pathogenesis of OSF.

  12. A 3.01-3.82 GHz CMOS LC voltage-controlled oscillator with 6.29% VCO-gain variation for WLAN applications

    Science.gov (United States)

    Xiaolong, Liu; Lei, Zhang; Li, Zhang; Yan, Wang; Zhiping, Yu

    2014-07-01

    A wideband low-phase-noise LC voltage-controlled oscillator (VCO) with low VCO gain (KVCO) variation for WLAN fractional-N frequency synthesizer application is proposed and designed on a 0.13-μm CMOS process. In order to achieve a low KVCO variation, an extra switched varactor array was added to the LC tank with the conventional switched capacitor array. Based on the proposed switched varactor array compensation technique, the measured KVCO is 43 MHz/V with only 6.29% variation across the entire tuning range. The proposed VCO provides a tuning range of 23.7% from 3.01 to 3.82 GHz, while consuming 9 mA of quiescent current from a 2.3 V supply. The VCO shows a low phase noise of -121.94 dBc/Hz at 1 MHz offset, from the 3.6 GHz carrier.

  13. Homeostatically maintained resting naïve CD4+ T cells resist latent HIV reactivation

    Directory of Open Access Journals (Sweden)

    Yasuko Tsunetsugu-Yokota

    2016-12-01

    Full Text Available Homeostatic proliferation (HSP is a major mechanism by which long-lived naïve and memory CD4+ T cells are maintained in vivo and suggested to contribute to the persistence of the latent HIV-1 reservoir. However, while many in vitro latency models rely on CD4+ T cells that were initially differentiated via T-cell receptor stimulation (TCR into memory/effector cells, latent infection of naïve resting CD4+ T cells maintained under HSP conditions has not been fully addressed. Here we describe an in vitro HSP culture system utilizing the cytokines IL-7 and IL-15 that allows studying latency in naïve resting CD4+ T cells. CD4+ T cells isolated from several healthy donors were infected with HIV pseudotypes expressing GFP and cultured under HSP conditions or TCR conditions as control. Cell proliferation, phenotype and GFP expression were analyzed by flow cytometry. RNA expression was quantified by qRT-PCR. Under HSP culture conditions, latently HIV-1 infected naïve cells are in part maintained in the non-dividing (= resting state. Although a few HIV-1 provirus+ cells were present in these resting GFP negative cells, the estimated level of GFP transcripts per infected cell seems to indicate a block at the post-transcriptional level. Interestingly, neither TCR nor the prototypic HDAC inhibitor SAHA were able to reactivate HIV-1 provirus from these cells. This lack of reactivation was not due to methylation of the HIV LTR. These results point to a mechanism of HIV control in HSP-cultured resting naïve CD4+ T cells that may be distinct from that in TCR-stimulated memory/effector T cells.

  14. Homeostatic Epithelial Renewal in the Gut Is Required for Dampening a Fatal Systemic Wound Response in Drosophila

    Directory of Open Access Journals (Sweden)

    Asuka Takeishi

    2013-03-01

    Full Text Available Effective defense responses involve the entire organism. To maintain body homeostasis after tissue damage, a systemic wound response is induced in which the response of each tissue is tightly orchestrated to avoid incomplete recovery or an excessive, damaging response. Here, we provide evidence that in the systemic response to wounding, an apoptotic caspase pathway is activated downstream of reactive oxygen species in the midgut enterocytes (ECs, cells distant from the wound site, in Drosophila. We show that a caspase-pathway mutant has defects in homeostatic gut cell renewal and that inhibiting caspase activity in fly ECs results in the production of systemic lethal factors after wounding. Our results indicate that wounding remotely controls caspase activity in ECs, which activates the tissue stem cell regeneration pathway in the gut to dampen the dangerous systemic wound reaction.

  15. AN OVERVIEW OF THE DEVELOPMENT OF LOW GAIN FEEDBACK AND LOW-AND-HIGH GAIN FEEDBACK

    Institute of Scientific and Technical Information of China (English)

    Zongli LIN

    2009-01-01

    Low gain feedback refers to certain families of stabilizing state feedback gains that are parameterized in a scalar and go to zero as the scalar decreases to zero. Low gain feedback was initially proposed to achieve semi-global stabilization of linear systems subject to input saturation. It was then combined with high gain feedback in different ways for solving various control problems. The resulting feedback laws are referred to as low-and-high gain feedback. Since the introduction of low gain feedback in the context of semi-global stabilization of linear systems subject to input saturation,there has been effort to develop alternative methods for low gain design, to characterize key features of low gain feedback, and to explore new applications of the low gain and low-and-high gain feedback.This paper reviews the developments in low gain and low-and-high gain feedback designs.

  16. Homeostatic imbalance of regulatory and effector T cells due to IL-2 deprivation amplifies murine lupus

    National Research Council Canada - National Science Library

    Jens Y. Humrich; Henner Morbach; Reinmar Undeutsch; Philipp Enghard; Stefan Rosenberger; Olivia Weigert; Lutz Kloke; Juliane Heimann; Timo Gaber; Susan Brandenburg; Alexander Scheffold; Jochen Huehn; Andreas Radbruch; Gerd-Rüdiger Burmester; Gabriela Riemekasten

    2010-01-01

    ...) are poorly understood. In the (NZBxNZW) F 1 mouse model of lupus, we found that CD4 + Foxp3 + Treg failed to maintain a competitive pool size in the peripheral lymphoid organs resulting in a progressive homeostatic imbalance of CD4...

  17. A cerebellar framework for predictive coding and homeostatic regulation in depressive disorder

    NARCIS (Netherlands)

    Schutter, D.J.L.G.

    2016-01-01

    Depressive disorder is associated with abnormalities in the processing of reward and punishment signals and disturbances in homeostatic regulation. These abnormalities are proposed to impair error minimization routines for reducing uncertainty. Several lines of research point towards a role of the c

  18. Homeostatic Synaptic Plasticity Can Explain Post-traumatic Epileptogenesis in Chronically Isolated Neocortex

    Science.gov (United States)

    Houweling, Arthur R.; Bazhenov, Maxim; Timofeev, Igor; Steriade, Mircea; Sejnowski, Terrence J.

    2010-01-01

    Chronically isolated neocortex develops chronic hyperexcitability and focal epileptogenesis in a period of days to weeks. The mechanisms operating in this model of post-traumatic epileptogenesis are not well understood. We hypothesized that the spontaneous burst discharges recorded in chronically isolated neocortex result from homeostatic plasticity (a mechanism generally assumed to stabilize neuronal activity) induced by low neuronal activity after deafferentation. To test this hypothesis we constructed computer models of neocortex incorporating a biologically based homeostatic plasticity rule that operates to maintain firing rates. After deafferentation, homeostatic upregulation of excitatory synapses on pyramidal cells, either with or without concurrent downregulation of inhibitory synapses or upregulation of intrinsic excitability, initiated slowly repeating burst discharges that closely resembled the epileptiform burst discharges recorded in chronically isolated neocortex. These burst discharges lasted a few hundred ms, propagated at 1–3 cm/s and consisted of large (10–15 mV) intracellular depolarizations topped by a small number of action potentials. Our results support a role for homeostatic synaptic plasticity as a novel mechanism of post-traumatic epileptogenesis. PMID:15483049

  19. A Presynaptic Glutamate Receptor Subunit Confers Robustness to Neurotransmission and Homeostatic Potentiation

    Directory of Open Access Journals (Sweden)

    Beril Kiragasi

    2017-06-01

    Full Text Available Homeostatic signaling systems are thought to interface with other forms of plasticity to ensure flexible yet stable levels of neurotransmission. The role of neurotransmitter receptors in this process, beyond mediating neurotransmission itself, is not known. Through a forward genetic screen, we have identified the Drosophila kainate-type ionotropic glutamate receptor subunit DKaiR1D to be required for the retrograde, homeostatic potentiation of synaptic strength. DKaiR1D is necessary in presynaptic motor neurons, localized near active zones, and confers robustness to the calcium sensitivity of baseline synaptic transmission. Acute pharmacological blockade of DKaiR1D disrupts homeostatic plasticity, indicating that this receptor is required for the expression of this process, distinct from developmental roles. Finally, we demonstrate that calcium permeability through DKaiR1D is necessary for baseline synaptic transmission, but not for homeostatic signaling. We propose that DKaiR1D is a glutamate autoreceptor that promotes robustness to synaptic strength and plasticity with active zone specificity.

  20. Requirement for Plk2 in orchestrated ras and rap signaling, homeostatic structural plasticity, and memory.

    Science.gov (United States)

    Lee, Kea Joo; Lee, Yeunkum; Rozeboom, Aaron; Lee, Ji-Yun; Udagawa, Noriko; Hoe, Hyang-Sook; Pak, Daniel T S

    2011-03-10

    Ras and Rap small GTPases are important for synaptic plasticity and memory. However, their roles in homeostatic plasticity are unknown. Here, we report that polo-like kinase 2 (Plk2), a homeostatic suppressor of overexcitation, governs the activity of Ras and Rap via coordination of their regulatory proteins. Plk2 directs elimination of Ras activator RasGRF1 and Rap inhibitor SPAR via phosphorylation-dependent ubiquitin-proteasome degradation. Conversely, Plk2 phosphorylation stimulates Ras inhibitor SynGAP and Rap activator PDZGEF1. These Ras/Rap regulators perform complementary functions to downregulate dendritic spines and AMPA receptors following elevated activity, and their collective regulation by Plk2 profoundly stimulates Rap and suppresses Ras. Furthermore, perturbation of Plk2 disrupts Ras and Rap signaling, prevents homeostatic shrinkage and loss of dendritic spines, and impairs proper memory formation. Our study demonstrates a critical role of Plk2 in the synchronized tuning of Ras and Rap and underscores the functional importance of this regulation in homeostatic synaptic plasticity. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. BACE1 Is Necessary for Experience-Dependent Homeostatic Synaptic Plasticity in Visual Cortex

    Directory of Open Access Journals (Sweden)

    Emily Petrus

    2014-01-01

    Full Text Available Alzheimer’s disease (AD is the most common form of age-related dementia, which is thought to result from overproduction and/or reduced clearance of amyloid-beta (Aβ peptides. Studies over the past few decades suggest that Aβ is produced in an activity-dependent manner and has physiological relevance to normal brain functions. Similarly, physiological functions for β- and γ-secretases, the two key enzymes that produce Aβ by sequentially processing the amyloid precursor protein (APP, have been discovered over recent years. In particular, activity-dependent production of Aβ has been suggested to play a role in homeostatic regulation of excitatory synaptic function. There is accumulating evidence that activity-dependent immediate early gene Arc is an activity “sensor,” which acts upstream of Aβ production and triggers AMPA receptor endocytosis to homeostatically downregulate the strength of excitatory synaptic transmission. We previously reported that Arc is critical for sensory experience-dependent homeostatic reduction of excitatory synaptic transmission in the superficial layers of visual cortex. Here we demonstrate that mice lacking the major neuronal β-secretase, BACE1, exhibit a similar phenotype: stronger basal excitatory synaptic transmission and failure to adapt to changes in visual experience. Our results indicate that BACE1 plays an essential role in sensory experience-dependent homeostatic synaptic plasticity in the neocortex.

  2. The Dendritic Cell Response to Classic, Emerging, and Homeostatic Danger Signals. Implications for Autoimmunity.

    Directory of Open Access Journals (Sweden)

    Paul Matthew Gallo

    2013-06-01

    Full Text Available Dendritic cells (DCs initiate and control immune responses, participate in the maintenance of immunological tolerance and are pivotal players in the pathogenesis of autoimmunity. In patients with autoimmune disease and in experimental animal models of autoimmunity, DCs show abnormalities in both numbers and activation state, expressing immunogenic levels of costimulatory molecules and pro-inflammatory cytokines. Exogenous and endogenous danger signals activate DCs to stimulate the immune response. Classic endogenous danger signals are released, activated, or secreted by host cells and tissues experiencing stress, damage, and non-physiologic cell death; and are therefore referred to as damage-associated molecular patterns (DAMPs. Some DAMPs are released from cells, where they are normally sequestered, during necrosis (e.g. heat shock proteins, uric acid, ATP, HMGB1, mitochondria-derived molecules. Others are actively secreted, like Type I Interferons. Here we discuss important DAMPs in the context of autoimmunity. For some, there is a clear pathogenic link (e.g. nucleic acids and lupus. For others, there is less evidence. Additionally, we explore emerging danger signals. These include inorganic materials and man-made technologies (e.g. nanomaterials developed as novel therapeutic approaches. Some nanomaterials can activate DCs and may trigger unintended inflammatory responses. Finally, we will review homeostatic danger signals, danger signals that do not derive directly from pathogens or dying cells but are associated with perturbations of tissue/cell homeostasis and may signal pathological stress. These signals, like acidosis, hypoxia and changes in osmolarity, also play a role in inflammation and autoimmunity.

  3. Glucose Homeostatic Law: Insulin Clearance Predicts the Progression of Glucose Intolerance in Humans.

    Directory of Open Access Journals (Sweden)

    Kaoru Ohashi

    Full Text Available Homeostatic control of blood glucose is regulated by a complex feedback loop between glucose and insulin, of which failure leads to diabetes mellitus. However, physiological and pathological nature of the feedback loop is not fully understood. We made a mathematical model of the feedback loop between glucose and insulin using time course of blood glucose and insulin during consecutive hyperglycemic and hyperinsulinemic-euglycemic clamps in 113 subjects with variety of glucose tolerance including normal glucose tolerance (NGT, impaired glucose tolerance (IGT and type 2 diabetes mellitus (T2DM. We analyzed the correlation of the parameters in the model with the progression of glucose intolerance and the conserved relationship between parameters. The model parameters of insulin sensitivity and insulin secretion significantly declined from NGT to IGT, and from IGT to T2DM, respectively, consistent with previous clinical observations. Importantly, insulin clearance, an insulin degradation rate, significantly declined from NGT, IGT to T2DM along the progression of glucose intolerance in the mathematical model. Insulin clearance was positively correlated with a product of insulin sensitivity and secretion assessed by the clamp analysis or determined with the mathematical model. Insulin clearance was correlated negatively with postprandial glucose at 2h after oral glucose tolerance test. We also inferred a square-law between the rate constant of insulin clearance and a product of rate constants of insulin sensitivity and secretion in the model, which is also conserved among NGT, IGT and T2DM subjects. Insulin clearance shows a conserved relationship with the capacity of glucose disposal among the NGT, IGT and T2DM subjects. The decrease of insulin clearance predicts the progression of glucose intolerance.

  4. Peripheral blood mononuclear cells: a potential source of homeostatic imbalance markers associated with obesity development.

    Science.gov (United States)

    Oliver, Paula; Reynés, Bàrbara; Caimari, Antoni; Palou, Andreu

    2013-04-01

    Peripheral blood mononuclear cells (PBMC) have a great potential for nutrition and obesity studies. PBMC reflect the nutritional response of key organs involved in energy homeostasis maintenance, which is altered in the obese state. Here, we aimed to determine the usefulness of PBMC as a source of early markers of obesity. To that purpose, we analysed whether PBMC could reflect the insensitivity to changes in feeding conditions associated with obesity during the development of this pathology. Expression of key genes central to energy metabolism was measured by Q-PCR in PBMC samples of normoweight (control) and cafeteria-fed (obese) rats in feeding, fasting and refeeding conditions. Samples were obtained monthly from 2 (beginning of cafeteria diet-feeding) to 6 months of age. In general terms, expression of genes related to fatty acid synthesis (Fasn, Srebp1) and adipogenesis (Pparg) decreased with fasting and increased with refeeding. Conversely, the expression of a key gene regulating beta-oxidation (Cpt1a) and the gene for an orexigenic neuropeptide (Npy)-in accordance with their metabolic role-increased with fasting and decreased with refeeding. This expression pattern disappeared in obese rats, in which insensitivity to feeding conditions was observed after only 1 month of cafeteria diet-feeding. Thus, during development, PBMC accurately reflect nutritional regulation of energy homeostasic genes and the insensitivity to feeding associated with obesity, even in the earlier stages with a low degree of overweight. For this reason, this set of blood cells could constitute a potential source of biomarkers of early homeostatic imbalance which would be useful in nutrition studies that could help prevent the occurrence of obesity.

  5. Distance-dependent homeostatic synaptic scaling mediated by A-type potassium channels

    Directory of Open Access Journals (Sweden)

    Hiroshi T Ito

    2009-11-01

    Full Text Available Many lines of evidence suggest that the efficacy of synapses on CA1 pyramidal neuron dendrites increases as a function of distance from the cell body. The strength of an individual synapse is also dynamically modulated by activity-dependent synaptic plasticity, which raises the question as to how a neuron can reconcile individual synaptic changes with the maintenance of the proximal-to-distal gradient of synaptic strength along the dendrites. As the density of A-type potassium channels exhibits a similar gradient from proximal (low-to-distal (high dendrites, the A-current may play a role in coordinating local synaptic changes with the global synaptic strength gradient. Here we describe a form of homeostatic plasticity elicited by conventional activity blockade (with TTX coupled with a block of the A-type potassium channel. Following A-type potassium channel inhibition for 12 hrs, recordings from CA1 somata revealed a significantly higher miniature excitatory postsynaptic current (mEPSC frequency, whereas in dendritic recordings, there was no change in mEPSC frequency. Consistent with mEPSC recordings, we observed a significant increase in AMPA receptor density in stratum pyramidale but not stratum radiatum. Based on these data, we propose that the differential distribution of A-type potassium channels along the apical dendrites may create a proximal-to-distal membrane potential gradient. This gradient may regulate AMPA receptor distribution along the same axis. Taken together, our results indicate that A-type potassium channels play an important role in controlling synaptic strength along the dendrites, which may help to maintain the computational capacity of the neuron.

  6. Time-varying auditory gain control in response to double-pulse stimuli in harbour porpoises is not mediated by a stapedial reflex

    Directory of Open Access Journals (Sweden)

    Asger Emil Munch Schrøder

    2017-04-01

    Full Text Available Echolocating animals reduce their output level and hearing sensitivity with decreasing echo delays, presumably to stabilize the perceived echo intensity during target approaches. In bats, this variation in hearing sensitivity is formed by a call-induced stapedial reflex that tapers off over time after the call. Here, we test the hypothesis that a similar mechanism exists in toothed whales by subjecting a trained harbour porpoise to a series of double sound pulses varying in delay and frequency, while measuring the magnitudes of the evoked auditory brainstem responses (ABRs. We find that the recovery of the ABR to the second pulse is frequency dependent, and that a stapedial reflex therefore cannot account for the reduced hearing sensitivity at short pulse delays. We propose that toothed whale auditory time-varying gain control during echolocation is not enabled by the middle ear as in bats, but rather by frequency-dependent mechanisms such as forward masking and perhaps higher-order control of efferent feedback to the outer hair cells.

  7. How voltage-gated calcium channels gate forms of homeostatic synaptic plasticity

    Directory of Open Access Journals (Sweden)

    C. Andrew eFrank

    2014-02-01

    Full Text Available Throughout life, animals face a variety of challenges such as developmental growth, the presence of toxins, or changes in temperature. Neuronal circuits and synapses respond to challenges by executing an array of neuroplasticity paradigms. Some paradigms allow neurons to up- or downregulate activity outputs, while countervailing ones ensure that outputs remain within appropriate physiological ranges. A growing body of evidence suggests that homeostatic synaptic plasticity (HSP is critical in the latter case. Voltage-gated calcium channels gate forms of HSP. Presynaptically, the aggregate data show that when synapse activity is weakened, homeostatic signaling systems can act to correct impairments, in part by increasing calcium influx through presynaptic CaV2-type channels. Increased calcium influx is often accompanied by parallel increases in the size of active zones and the size of the readily releasable pool of presynaptic vesicles. These changes coincide with homeostatic enhancements of neurotransmitter release. Postsynaptically, there is a great deal of evidence that reduced network activity and loss of calcium influx through CaV1-type calcium channels also results in adaptive homeostatic signaling. Some adaptations drive presynaptic enhancements of vesicle pool size and turnover rate via retrograde signaling, as well as de novo insertion of postsynaptic neurotransmitter receptors. Enhanced calcium influx through CaV1 after network activation or single cell stimulation can elicit the opposite response – homeostatic depression via removal of excitatory receptors.There exist intriguing links between HSP and calcium channelopathies – such as forms of epilepsy, migraine, ataxia, and myasthenia. The episodic nature of some of these disorders suggests alternating periods of stable and unstable function. Uncovering information about how calcium channels are regulated in the context of HSP could be relevant toward understanding these and other

  8. Analysis of reactor power behaviour using estimation of period for the gain adaptation in a state feedback controller; Atomos para el desarrollo de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Benitez R, J.S. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico); Perez C, J.H. [CINVESTAV, IPN, A.P. 14740 07000 Mexico D.F. (Mexico); Rivero G, T. [ITT, 50140 Metepec, Estado de Mexico (Mexico)

    2008-07-01

    In this paper a novel procedure for power regulation in a TRIGA Mark III nuclear reactor is presented. The control scheme combines state variable feedback with a first order predictor, which is incorporated to speed up the power response of the reactor without exceeding the safety requirement imposed by the reactor period. The simulation results using the proposed control strategy attains different values of steady-state power from different values of initial power in short time, complying at all times with the safety restriction imposed on the reactor period. The predictor, derived from the theory of first order numerical integration, produces very good results during the ascent of power. These results include a fast response and independence of the wide variety of potential operating conditions something not easy and even impossible to obtain with other procedures. By using this control scheme, the reactor period is maintained within safety limits during the start up of the reactor, which is normally the operating condition where an occurrence of a period scram is common. However, the predictor can not be used when the power is reaching the desired power level because the instantaneous power increases far above the desired level. Thus, when the power increases above certain power level, the state feedback gain is set constant to a predefined value. This causes some oscillations that decrease in a few seconds. Afterwards, the power response smoothly approaches, with a small overshoot, the desired power. This constraint on the use of the predictor prevents the unbounded increase of the neutron power. The control law proposed requires all the system's state variables. Since only the neutron power is available, it is necessary the estimation of the non measurable states. The key issue of the existence of a solution to this problem has been previously considered. One of the conclusions is that the point kinetic equations are observable under certain restrictions

  9. Design of Constant-Gain Digitally Controlled Oscillator%增益恒定的数控振荡器设计

    Institute of Scientific and Technical Information of China (English)

    陈鑫; 黄辉; 吴宁

    2012-01-01

    针对驱动能力可调的数控振荡器在输出频率范围内增益变化较大的问题,提出了一种电路设计方法,通过该方法设计出的数控振荡器结构具有增益恒定的特点.在SMIC 0.18 μm logic 1P6M CMOS工艺下设计并实现了一个采用该振荡器结构的数控锁相环,数控振荡器的面积为0.025 mm2.实测数据表明,该数控振荡器输出的频率范围为76 ~ 208 MHz.当锁相环输出208 MHz高频时钟时,四分频后的峰峰值抖动为110 ps,均方根抖动为14.82 ps,数控振荡器的功耗为1.512 mW.%The gain of the driven-adjustable digitally controlled oscillator (DCO) varies largely in the output frequency range. To solve the problem, a circuit design method is presented to keep the DCO gain invariant in time-domain. To verify the proposed design method, a digitally controlled phase-locked loop (DCPLL) with the DCO is implemented by SMIC 0.18 祄 logic 1P6M CMOS technology. The area of the DCO is 0.025 mm2. The measured results show that the frequency range of the DCO is from 76 MHz to 208 MHz. When the frequency of the DCO is 208 MHz, the measured peak-to-peak jitter and cycle jitter of the corresponding four-divided clock are 110 ps and 14.82 ps, respectively. The corresponding power of the DCO is 1.512 mW.

  10. The relationship between weight gain during pregnancy and urinary tract infections in pregnant women of Shahrekord, by using the “Nested case-control study”, in 2013

    Science.gov (United States)

    Rejali, Mehri; Ahmadi, Seyede Soghra; Hassanzadeh, Akbar; Yazdani, Rezvan; Ahmadi, Seyede Nafiseh

    2015-01-01

    Background and Objectives: Pregnancy is one of the most important and risky periods in mothers and the fetus life, which plays a key role in health and social activity of the person, family and community. This study is trying to see if there is a relation between increasing weight and urinary tract infection (UTI) in pregnancy by using the open nested case-control study in the city of Shahrekord. Materials and Methods: In a nested case-control study, one cohort including 832 patients was examined until week 26 to 30 of pregnancy and their UTIs were studied. The required information was collected by examining the health records of pregnant women and completion of the data registration forms. Data collection was controlled by using SPSS and analyzed by using an independent t-test, Chi-square test, Pearson correlation and logistic regression. Results: According to the results of the cohort study with 832 individuals, average weight gain of the group with a UTI was 11.13 ± 3.9 kg and it was 10.63 ± 3.9 kg in the group without UTI, showing no statistically significant difference (P = 0.245). According to the results, genitourinary problems had the highest predictive value for UTIs and the numbers of infertility and the childbirth variables were in the second and third positions, respectively. Conclusion: According to the results study we can conclude that screening and treatment of UTIs have been on time and appropriate in health systems of the city of Shahrekord which have lead to the reduction of infant and maternal diseases even with the condition in having no UTI, and continuing this process for screening and treatment is recommended. PMID:27462626

  11. Anti-homeostatic synaptic plasticity of glycine receptor function after chronic strychnine in developing cultured mouse spinal neurons.

    Science.gov (United States)

    Carrasco, M A; Castro, P A; Sepulveda, F J; Cuevas, M; Tapia, J C; Izaurieta, P; van Zundert, B; Aguayo, L G

    2007-03-01

    In this study, we describe a novel form of anti-homeostatic plasticity produced after culturing spinal neurons with strychnine, but not bicuculline or 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Strychnine caused a large increase in network excitability, detected as spontaneous synaptic currents and calcium transients. The calcium transients were associated with action potential firing and activation of gamma-aminobutyric acid (GABA(A)) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors as they were blocked by tetrodotoxin (TTX), bicuculline, and CNQX. After chronic blockade of glycine receptors (GlyRs), the frequency of synaptic transmission showed a significant enhancement demonstrating the phenomenon of anti-homeostatic plasticity. Spontaneous inhibitory glycinergic currents in treated cells showed a fourfold increase in frequency (from 0.55 to 2.4 Hz) and a 184% increase in average peak amplitude compared with control. Furthermore, the augmentation in excitability accelerated the decay time constant of miniature inhibitory post-synaptic currents. Strychnine caused an increase in GlyR current density, without changes in the apparent affinity. These findings support the idea of a post-synaptic action that partly explains the increase in synaptic transmission. This phenomenon of synaptic plasticity was blocked by TTX, an antibody against brain-derived neurotrophic factor (BDNF) and K252a suggesting the involvement of the neuronal activity-dependent BDNF-TrkB signaling pathway. These results show that the properties of GlyRs are regulated by the degree of neuronal activity in the developing network.

  12. A mathematical model of cancer stem cell driven tumor initiation: implications of niche size and loss of homeostatic regulatory mechanisms.

    Directory of Open Access Journals (Sweden)

    Sara N Gentry

    Full Text Available Hierarchical organized tissue structures, with stem cell driven cell differentiation, are critical to the homeostatic maintenance of most tissues, and this underlying cellular architecture is potentially a critical player in the development of a many cancers. Here, we develop a mathematical model of mutation acquisition to investigate how deregulation of the mechanisms preserving stem cell homeostasis contributes to tumor initiation. A novel feature of the model is the inclusion of both extrinsic and intrinsic chemical signaling and interaction with the niche to control stem cell self-renewal. We use the model to simulate the effects of a variety of types and sequences of mutations and then compare and contrast all mutation pathways in order to determine which ones generate cancer cells fastest. The model predicts that the sequence in which mutations occur significantly affects the pace of tumorigenesis. In addition, tumor composition varies for different mutation pathways, so that some sequences generate tumors that are dominated by cancerous cells with all possible mutations, while others are primarily comprised of cells that more closely resemble normal cells with only one or two mutations. We are also able to show that, under certain circumstances, healthy stem cells diminish due to the displacement by mutated cells that have a competitive advantage in the niche. Finally, in the event that all homeostatic regulation is lost, exponential growth of the cancer population occurs in addition to the depletion of normal cells. This model helps to advance our understanding of how mutation acquisition affects mechanisms that influence cell-fate decisions and leads to the initiation of cancers.

  13. Modeling energy intake by adding homeostatic feedback and drug intervention.

    Science.gov (United States)

    Gennemark, Peter; Hjorth, Stephan; Gabrielsson, Johan

    2015-02-01

    Energy intake (EI) is a pivotal biomarker used in quantification approaches to metabolic disease processes such as obesity, diabetes, and growth disorders. Eating behavior is however under both short-term and long-term control. This control system manifests itself as tolerance and rebound phenomena in EI, when challenged by drug treatment or diet restriction. The paper describes a model with the capability to capture physiological counter-regulatory feedback actions triggered by energy imbalances. This feedback is general as it handles tolerance to both increases and decreases in EI, and works in both acute and chronic settings. A drug mechanism function inhibits (or stimulates) EI. The deviation of EI relative to a reference level (set-point) serves as input to a non-linear appetite control signal which in turn impacts EI in parallel to the drug intervention. Three examples demonstrate the potential usefulness of the model in both acute and chronic dosing situations. The model shifts the predicted concentration-response relationship rightwardly at lower concentrations, in contrast to models that do not handle functional adaptation. A fourth example further shows that the model may qualitatively explain differences in rate and extent of adaptation in observed EI and its concomitants in both rodents and humans.

  14. Basolateral amygdala response to food cues in the absence of hunger is associated with weight gain susceptibility.

    Science.gov (United States)

    Sun, Xue; Kroemer, Nils B; Veldhuizen, Maria G; Babbs, Amanda E; de Araujo, Ivan E; Gitelman, Darren R; Sherwin, Robert S; Sinha, Rajita; Small, Dana M

    2015-05-20

    In rodents, food-predictive cues elicit eating in the absence of hunger (Weingarten, 1983). This behavior is disrupted by the disconnection of amygdala pathways to the lateral hypothalamus (Petrovich et al., 2002). Whether this circuit contributes to long-term weight gain is unknown. Using fMRI in 32 healthy individuals, we demonstrate here that the amygdala response to the taste of a milkshake when sated but not hungry positively predicts weight change. This effect is independent of sex, initial BMI, and total circulating ghrelin levels, but it is only present in individuals who do not carry a copy of the A1 allele of the Taq1A polymorphism. In contrast, A1 allele carriers, who have decreased D2 receptor density (Blum et al., 1996), show a positive association between caudate response and weight change. Regardless of genotype, however, dynamic causal modeling supports unidirectional gustatory input from basolateral amygdala (BLA) to hypothalamus in sated subjects. This finding suggests that, as in rodents, external cues gain access to the homeostatic control circuits of the human hypothalamus via the amygdala. In contrast, during hunger, gustatory inputs enter the hypothalamus and drive bidirectional connectivity with the amygdala. These findings implicate the BLA-hypothalamic circuit in long-term weight change related to nonhomeostatic eating and provide compelling evidence that distinct brain mechanisms confer susceptibility to weight gain depending upon individual differences in dopamine signaling.

  15. Low Dark-Current, High Current-Gain of PVK/ZnO Nanoparticles Composite-Based UV Photodetector by PN-Heterojunction Control.

    Science.gov (United States)

    Lee, Sang-Won; Cha, Seung-Hwan; Choi, Kyung-Jae; Kang, Byoung-Ho; Lee, Jae-Sung; Kim, Sae-Wan; Kim, Ju-Seong; Jeong, Hyun-Min; Gopalan, Sai-Anand; Kwon, Dae-Hyuk; Kang, Shin-Won

    2016-01-07

    We propose a solution-processable ultraviolet (UV) photodetector with a pn-heterojunction hybrid photoactive layer (HPL) that is composed of poly-n-vinylcarbazole (PVK) as a p-type polymer and ZnO nanoparticles (NPs) as an n-type metal oxide. To observe the effective photo-inducing ability of the UV photodetector, we analyzed the optical and electrical properties of HPL which is controlled by the doping concentration of n-type ZnO NPs in PVK matrix. Additionally, we confirmed that the optical properties of HPL dominantly depend on the ZnO NPs from the UV-vis absorption and the photoluminescence (PL) spectral measurements. This HPL can induce efficient charge transfer in the localized narrow pn-heterojunction domain and increases the photocurrent gain. It is essential that proper doping concentration of n-type ZnO NPs in polymer matrix is obtained to improve the performance of the UV photodetector. When the ZnO NPs are doped with the optimized concentration of 3.4 wt.%, the electrical properties of the photocurrent are significantly increased. The ratio of the photocurrent was approximately 10³ higher than that of the dark current.

  16. Low Dark-Current, High Current-Gain of PVK/ZnO Nanoparticles Composite-Based UV Photodetector by PN-Heterojunction Control

    Directory of Open Access Journals (Sweden)

    Sang-Won Lee

    2016-01-01

    Full Text Available We propose a solution-processable ultraviolet (UV photodetector with a pn-heterojunction hybrid photoactive layer (HPL that is composed of poly-n-vinylcarbazole (PVK as a p-type polymer and ZnO nanoparticles (NPs as an n-type metal oxide. To observe the effective photo-inducing ability of the UV photodetector, we analyzed the optical and electrical properties of HPL which is controlled by the doping concentration of n-type ZnO NPs in PVK matrix. Additionally, we confirmed that the optical properties of HPL dominantly depend on the ZnO NPs from the UV-vis absorption and the photoluminescence (PL spectral measurements. This HPL can induce efficient charge transfer in the localized narrow pn-heterojunction domain and increases the photocurrent gain. It is essential that proper doping concentration of n-type ZnO NPs in polymer matrix is obtained to improve the performance of the UV photodetector. When the ZnO NPs are doped with the optimized concentration of 3.4 wt.%, the electrical properties of the photocurrent are significantly increased. The ratio of the photocurrent was approximately 103 higher than that of the dark current.

  17. Active video games as a tool to prevent excessive weight gain in adolescents: rationale, design and methods of a randomized controlled trial

    Science.gov (United States)

    2014-01-01

    Background Excessive body weight, low physical activity and excessive sedentary time in youth are major public health concerns. A new generation of video games, the ones that require physical activity to play the games –i.e. active games- may be a promising alternative to traditional non-active games to promote physical activity and reduce sedentary behaviors in youth. The aim of this manuscript is to describe the design of a study evaluating the effects of a family oriented active game intervention, incorporating several motivational elements, on anthropometrics and health behaviors in adolescents. Methods/Design The study is a randomized controlled trial (RCT), with non-active gaming adolescents aged 12 – 16 years old randomly allocated to a ten month intervention (receiving active games, as well as an encouragement to play) or a waiting-list control group (receiving active games after the intervention period). Primary outcomes are adolescents’ measured BMI-SDS (SDS = adjusted for mean standard deviation score), waist circumference-SDS, hip circumference and sum of skinfolds. Secondary outcomes are adolescents’ self-reported time spent playing active and non-active games, other sedentary activities and consumption of sugar-sweetened beverages. In addition, a process evaluation is conducted, assessing the sustainability of the active games, enjoyment, perceived competence, perceived barriers for active game play, game context, injuries from active game play, activity replacement and intention to continue playing the active games. Discussion This is the first adequately powered RCT including normal weight adolescents, evaluating a reasonably long period of provision of and exposure to active games. Next, strong elements are the incorporating motivational elements for active game play and a comprehensive process evaluation. This trial will provide evidence regarding the potential contribution of active games in prevention of excessive weight gain in

  18. Homeostatic regulation of meiotic DSB formation by ATM/ATR

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Tim J.; Wardell, Kayleigh; Garcia, Valerie; Neale, Matthew J., E-mail: m.neale@sussex.ac.uk

    2014-11-15

    Ataxia–telangiectasia mutated (ATM) and RAD3-related (ATR) are widely known as being central players in the mitotic DNA damage response (DDR), mounting responses to DNA double-strand breaks (DSBs) and single-stranded DNA (ssDNA) respectively. The DDR signalling cascade couples cell cycle control to damage-sensing and repair processes in order to prevent untimely cell cycle progression while damage still persists [1]. Both ATM/ATR are, however, also emerging as essential factors in the process of meiosis; a specialised cell cycle programme responsible for the formation of haploid gametes via two sequential nuclear divisions. Central to achieving accurate meiotic chromosome segregation is the introduction of numerous DSBs spread across the genome by the evolutionarily conserved enzyme, Spo11. This review seeks to explore and address how cells utilise ATM/ATR pathways to regulate Spo11-DSB formation, establish DSB homeostasis and ensure meiosis is completed unperturbed.

  19. Homeostatic regulation of meiotic DSB formation by ATM/ATR.

    Science.gov (United States)

    Cooper, Tim J; Wardell, Kayleigh; Garcia, Valerie; Neale, Matthew J

    2014-11-15

    Ataxia-telangiectasia mutated (ATM) and RAD3-related (ATR) are widely known as being central players in the mitotic DNA damage response (DDR), mounting responses to DNA double-strand breaks (DSBs) and single-stranded DNA (ssDNA) respectively. The DDR signalling cascade couples cell cycle control to damage-sensing and repair processes in order to prevent untimely cell cycle progression while damage still persists [1]. Both ATM/ATR are, however, also emerging as essential factors in the process of meiosis; a specialised cell cycle programme responsible for the formation of haploid gametes via two sequential nuclear divisions. Central to achieving accurate meiotic chromosome segregation is the introduction of numerous DSBs spread across the genome by the evolutionarily conserved enzyme, Spo11. This review seeks to explore and address how cells utilise ATM/ATR pathways to regulate Spo11-DSB formation, establish DSB homeostasis and ensure meiosis is completed unperturbed.

  20. Effective Strategies to Recruit Young Adults Into the TXT2BFiT mHealth Randomized Controlled Trial for Weight Gain Prevention

    Science.gov (United States)

    Balestracci, Kate; Wong, Annette TY; Hebden, Lana; McGeechan, Kevin; Denney-Wilson, Elizabeth; Harris, Mark F; Phongsavan, Philayrath; Bauman, Adrian; Allman-Farinelli, Margaret

    2015-01-01

    Background Younger adults are difficult to engage in preventive health, yet in Australia they are gaining more weight and increasing in waist circumference faster than middle-to-older adults. A further challenge to engaging 18- to 35-year-olds in interventions is the limited reporting of outcomes of recruitment strategies. Objective This paper describes the outcomes of strategies used to recruit young adults to a randomized controlled trial (RCT), healthy lifestyle mHealth program, TXT2BFiT, for prevention of weight gain. The progression from enquiry through eligibility check to randomization into the trial and the costs of recruitment strategies are reported. Factors associated with nonparticipation are explored. Methods Participants were recruited either via letters of invitation from general practitioners (GPs) or via electronic or print advertisements, including Facebook and Google—social media and advertising—university electronic newsletters, printed posters, mailbox drops, and newspapers. Participants recruited from GP invitation letters had an appointment booked with their GP for eligibility screening. Those recruited from other methods were sent an information pack to seek approval to participate from their own GP. The total number and source of enquiries were categorized according to eligibility and subsequent completion of steps to enrolment. Cost data and details of recruitment strategies were recorded. Results From 1181 enquiries in total from all strategies, 250 (21.17%) participants were randomized. A total of 5311 invitation letters were sent from 12 GP practices—16 participating GPs. A total of 131 patients enquired with 68 participants randomized (68/74 of those eligible, 92%). The other recruitment methods yielded the remaining 182 randomized participants. Enrolment from print media was 26% of enquiries, from electronic media was 20%, and from other methods was 3%. Across all strategies the average cost of recruitment was Australian Dollar

  1. Effective Strategies to Recruit Young Adults Into the TXT2BFiT mHealth Randomized Controlled Trial for Weight Gain Prevention.

    Science.gov (United States)

    Partridge, Stephanie R; Balestracci, Kate; Wong, Annette Ty; Hebden, Lana; McGeechan, Kevin; Denney-Wilson, Elizabeth; Harris, Mark F; Phongsavan, Philayrath; Bauman, Adrian; Allman-Farinelli, Margaret

    2015-06-05

    Younger adults are difficult to engage in preventive health, yet in Australia they are gaining more weight and increasing in waist circumference faster than middle-to-older adults. A further challenge to engaging 18- to 35-year-olds in interventions is the limited reporting of outcomes of recruitment strategies. This paper describes the outcomes of strategies used to recruit young adults to a randomized controlled trial (RCT), healthy lifestyle mHealth program, TXT2BFiT, for prevention of weight gain. The progression from enquiry through eligibility check to randomization into the trial and the costs of recruitment strategies are reported. Factors associated with nonparticipation are explored. Participants were recruited either via letters of invitation from general practitioners (GPs) or via electronic or print advertisements, including Facebook and Google-social media and advertising-university electronic newsletters, printed posters, mailbox drops, and newspapers. Participants recruited from GP invitation letters had an appointment booked with their GP for eligibility screening. Those recruited from other methods were sent an information pack to seek approval to participate from their own GP. The total number and source of enquiries were categorized according to eligibility and subsequent completion of steps to enrolment. Cost data and details of recruitment strategies were recorded. From 1181 enquiries in total from all strategies, 250 (21.17%) participants were randomized. A total of 5311 invitation letters were sent from 12 GP practices-16 participating GPs. A total of 131 patients enquired with 68 participants randomized (68/74 of those eligible, 92%). The other recruitment methods yielded the remaining 182 randomized participants. Enrolment from print media was 26% of enquiries, from electronic media was 20%, and from other methods was 3%. Across all strategies the average cost of recruitment was Australian Dollar (AUD) $139 per person. The least expensive

  2. PI fussy multimodal controller of programmed gains for the operation in the wide range of a turbo gas unit; Controlador PI difuso multimodo de ganancias programadas para la operacion en rango amplio de una unidad turbogas

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Martinez, Arnulfo A.

    2004-11-15

    In this thesis work it was developed a new control algorithm which merges the characteristics of multimode control, gain scheduling control and fuzzy logic techniques, in order to obtain a control system which gives a better gas turbine speed and load control performance, as compared to the current control systems, which are based on conventional PI control algorithms. This new algorithm is intended to provide a better quality control system, which provides both better disturbance rejection response, as well as better reference tracking response. Switching logic (multimode control) and interpolation strategy (gain scheduling) implementation problems are solved applying fuzzy controllers, which retain the advantages of both strategies for non lineal processes in wide operation regions. Since the controllers implemented by the fuzzy system rules are of the same type (PI, Proportional Integral), the multimode gain scheduling fuzzy controller design was reduced to the design of a gain scheduling fuzzy PI controller (PI-GSF). In order to define the gain scheduling scheme, three well-known gain scheduling fuzzy controller design approaches were analyzed and the interpolation mechanism of each of them were compared. The incorporation of a generalized PI controller structure in the local controllers that conform the PI-GSF (see chapter 4), allowed to generate a better control action for both disturbance rejection and reference tracking. As a final product a PI-GSF controller was obtained, which constitutes a more effective control strategy and showed to be a viable solution to the outlined technological problem. With the PI-GSF controller the speed control performance of the generating unit during startup stage, as well as the load control during the generation stage were considerably improved, as compared to the performance obtained with the conventional PI. [Spanish] En este trabajo de tesis se desarrollo un nuevo algoritmo de control que conjunta las caracteristicas de

  3. Sleep recalibrates homeostatic and associative synaptic plasticity in the human cortex.

    Science.gov (United States)

    Kuhn, Marion; Wolf, Elias; Maier, Jonathan G; Mainberger, Florian; Feige, Bernd; Schmid, Hanna; Bürklin, Jan; Maywald, Sarah; Mall, Volker; Jung, Nikolai H; Reis, Janine; Spiegelhalder, Kai; Klöppel, Stefan; Sterr, Annette; Eckert, Anne; Riemann, Dieter; Normann, Claus; Nissen, Christoph

    2016-08-23

    Sleep is ubiquitous in animals and humans, but its function remains to be further determined. The synaptic homeostasis hypothesis of sleep-wake regulation proposes a homeostatic increase in net synaptic strength and cortical excitability along with decreased inducibility of associative synaptic long-term potentiation (LTP) due to saturation after sleep deprivation. Here we use electrophysiological, behavioural and molecular indices to non-invasively study net synaptic strength and LTP-like plasticity in humans after sleep and sleep deprivation. We demonstrate indices of increased net synaptic strength (TMS intensity to elicit a predefined amplitude of motor-evoked potential and EEG theta activity) and decreased LTP-like plasticity (paired associative stimulation induced change in motor-evoked potential and memory formation) after sleep deprivation. Changes in plasma BDNF are identified as a potential mechanism. Our study indicates that sleep recalibrates homeostatic and associative synaptic plasticity, believed to be the neural basis for adaptive behaviour, in humans.

  4. Sleep recalibrates homeostatic and associative synaptic plasticity in the human cortex

    Science.gov (United States)

    Kuhn, Marion; Wolf, Elias; Maier, Jonathan G.; Mainberger, Florian; Feige, Bernd; Schmid, Hanna; Bürklin, Jan; Maywald, Sarah; Mall, Volker; Jung, Nikolai H.; Reis, Janine; Spiegelhalder, Kai; Klöppel, Stefan; Sterr, Annette; Eckert, Anne; Riemann, Dieter; Normann, Claus; Nissen, Christoph

    2016-01-01

    Sleep is ubiquitous in animals and humans, but its function remains to be further determined. The synaptic homeostasis hypothesis of sleep–wake regulation proposes a homeostatic increase in net synaptic strength and cortical excitability along with decreased inducibility of associative synaptic long-term potentiation (LTP) due to saturation after sleep deprivation. Here we use electrophysiological, behavioural and molecular indices to non-invasively study net synaptic strength and LTP-like plasticity in humans after sleep and sleep deprivation. We demonstrate indices of increased net synaptic strength (TMS intensity to elicit a predefined amplitude of motor-evoked potential and EEG theta activity) and decreased LTP-like plasticity (paired associative stimulation induced change in motor-evoked potential and memory formation) after sleep deprivation. Changes in plasma BDNF are identified as a potential mechanism. Our study indicates that sleep recalibrates homeostatic and associative synaptic plasticity, believed to be the neural basis for adaptive behaviour, in humans. PMID:27551934

  5. Ag-dependent (in silico) approach implies a deterministic kinetics for homeostatic memory cell turnover

    CERN Document Server

    de Castro, Alexandre; Herai, Roberto

    2011-01-01

    Verhulst-like mathematical modeling has been used to investigate several complex biological issues, such as immune memory equilibrium and cell-mediated immunity in mammals. The regulation mechanisms of both these processes are still not sufficiently understood. In a recent paper, Choo et al. [J. Immunol., v. 185, pp. 3436-44, 2010], used an Ag-independent approach to quantitatively analyze memory cell turnover from some empirical data, and concluded that immune homeostasis behaves stochastically, rather than deterministically. In the paper here presented, we use an in silico Ag-dependent approach to simulate the process of antigenic mutation and study its implications for memory dynamics. Our results have suggested a deterministic kinetics for homeostatic equilibrium, what contradicts the Choo et al. findings. Accordingly, our calculations are an indication that a more extensive empirical protocol for studying the homeostatic turnover should be considered.

  6. Homeostatic structural plasticity can account for topology changes following deafferentation and focal stroke

    Directory of Open Access Journals (Sweden)

    Markus eButz

    2014-10-01

    Full Text Available After brain lesions caused by tumors or stroke, or after lasting loss of input (deafferentation, inter- and intra-regional brain networks respond with complex changes in topology. Not only areas directly affected by the lesion but also regions remote from the lesion site may alter their connectivity---a phenomenon known as diaschisis. Changes in network topology after brain lesions can lead to cognitive decline and increasing functional disability. However, the principles governing changes in network topology are poorly understood. Here, we investigated whether homeostatic structural plasticity can account for changes in network topology after deafferentation and brain lesions. Homeostatic structural plasticity postulates that neurons aim to maintain a desired level of electrical activity by deleting synapses when their activity is too high and by providing new synaptic contacts when their activity becomes too low. Using our Model of Structural Plasticity, we explored the consequences of local changes in connectivity induced by a focal loss of input for global network topology. In accordance with experimental and clinical data, we found that after partial deafferentation, the model network as a whole became more random, although it maintained its small-world topology, while deafferentated neurons increased their betweenness centrality as they rewired and returned to the homeostatic range of activity. Furthermore, their degree distributions became more tailed, indicating the emergence of hub neurons. Deafferented neurons also showed an increase in their global but a decrease in their local efficiency. Together, our results suggest that homeostatic structural plasticity may be an important driving force for lesion-induced network reorganization. Computational models with structural plasticity may therefore provide novel insights into the mechanics of brain recovery and inspire novel treatments of brain damage.

  7. Rivalry of homeostatic and sensory-evoked emotions: Dehydration attenuates olfactory disgust and its neural correlates.

    Science.gov (United States)

    Meier, Lea; Friedrich, Hergen; Federspiel, Andrea; Jann, Kay; Morishima, Yosuke; Landis, Basile Nicolas; Wiest, Roland; Strik, Werner; Dierks, Thomas

    2015-07-01

    Neural correlates have been described for emotions evoked by states of homeostatic imbalance (e.g. thirst, hunger, and breathlessness) and for emotions induced by external sensory stimulation (such as fear and disgust). However, the neurobiological mechanisms of their interaction, when they are experienced simultaneously, are still unknown. We investigated the interaction on the neurobiological and the perceptional level using subjective ratings, serum parameters, and functional magnetic resonance imaging (fMRI) in a situation of emotional rivalry, when both a homeostatic and a sensory-evoked emotion were experienced at the same time. Twenty highly dehydrated male subjects rated a disgusting odor as significantly less repulsive when they were thirsty. On the neurobiological level, we found that this reduction in subjective disgust during thirst was accompanied by a significantly reduced neural activity in the insular cortex, a brain area known to be considerably involved in processing of disgust. Furthermore, during the experience of disgust in the satiated condition, we observed a significant functional connectivity between brain areas responding to the disgusting odor, which was absent during the stimulation in the thirsty condition. These results suggest interference of conflicting emotions: an acute homeostatic imbalance can attenuate the experience of another emotion evoked by the sensory perception of a potentially harmful external agent. This finding offers novel insights with regard to the behavioral relevance of biologically different types of emotions, indicating that some types of emotions are more imperative for behavior than others. As a general principle, this modulatory effect during the conflict of homeostatic and sensory-evoked emotions may function to safeguard survival. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Homeostatic structural plasticity can account for topology changes following deafferentation and focal stroke.

    Science.gov (United States)

    Butz, Markus; Steenbuck, Ines D; van Ooyen, Arjen

    2014-01-01

    After brain lesions caused by tumors or stroke, or after lasting loss of input (deafferentation), inter- and intra-regional brain networks respond with complex changes in topology. Not only areas directly affected by the lesion but also regions remote from the lesion may alter their connectivity-a phenomenon known as diaschisis. Changes in network topology after brain lesions can lead to cognitive decline and increasing functional disability. However, the principles governing changes in network topology are poorly understood. Here, we investigated whether homeostatic structural plasticity can account for changes in network topology after deafferentation and brain lesions. Homeostatic structural plasticity postulates that neurons aim to maintain a desired level of electrical activity by deleting synapses when neuronal activity is too high and by providing new synaptic contacts when activity is too low. Using our Model of Structural Plasticity, we explored how local changes in connectivity induced by a focal loss of input affected global network topology. In accordance with experimental and clinical data, we found that after partial deafferentation, the network as a whole became more random, although it maintained its small-world topology, while deafferentated neurons increased their betweenness centrality as they rewired and returned to the homeostatic range of activity. Furthermore, deafferentated neurons increased their global but decreased their local efficiency and got longer tailed degree distributions, indicating the emergence of hub neurons. Together, our results suggest that homeostatic structural plasticity may be an important driving force for lesion-induced network reorganization and that the increase in betweenness centrality of deafferentated areas may hold as a biomarker for brain repair.

  9. Effects of lifestyle intervention on dietary intake, physical activity level, and gestational weight gain in pregnant women with different pre-pregnancy Body Mass Index in a randomized control trial.

    Science.gov (United States)

    Hui, Amy Leung; Back, Lisa; Ludwig, Sora; Gardiner, Phillip; Sevenhuysen, Gustaaf; Dean, Heather J; Sellers, Elisabeth; McGavock, Jonathan; Morris, Margaret; Jiang, Depeng; Shen, Garry X

    2014-09-24

    The objectives of this study were to assess the efficacy of lifestyle intervention on gestational weight gain in pregnant women with normal and above normal body mass index (BMI) in a randomized controlled trial. A total of 116 pregnant women (pregnant women completed the program. Participants were randomized into intervention and control groups. Women in the intervention group received weekly trainer-led group exercise sessions, instructed home exercise for 3-5-times/week during 20-36 weeks of gestation, and dietary counseling twice during pregnancy. Participants in the control group did not receive the intervention. All participants completed a physical activity questionnaire and a 3-day food record at enrolment and 2 months after enrolment. The participants in the intervention group with normal pre-pregnancy BMI (≤24.9 kg/M2, n = 30) had lower gestational weight gain (GWG), offspring birth weight and excessive gestational weight gain (EGWG) on pregnancy weight gain compared to the control group (n = 27, p changes were not detected between the intervention (n = 27) and control group (n = 29) in the above normal pre-pregnancy BMI participants. Intervention reduced total calorie, total fat, saturated fat and cholesterol intake were detected in women with normal or above normal pre-pregnancy BMI compared to the control group (p pregnant women with normal, but not above normal, pre-pregnancy BMI, which was associated with increased physical activity and decreased carbohydrate intake. NCT00486629.

  10. Homeostatic imbalance of regulatory and effector T cells due to IL-2 deprivation amplifies murine lupus.

    Science.gov (United States)

    Humrich, Jens Y; Morbach, Henner; Undeutsch, Reinmar; Enghard, Philipp; Rosenberger, Stefan; Weigert, Olivia; Kloke, Lutz; Heimann, Juliane; Gaber, Timo; Brandenburg, Susan; Scheffold, Alexander; Huehn, Jochen; Radbruch, Andreas; Burmester, Gerd-Rüdiger; Riemekasten, Gabriela

    2010-01-05

    The origins and consequences of a regulatory T cell (Treg) disorder in systemic lupus erythematosus (SLE) are poorly understood. In the (NZBxNZW) F(1) mouse model of lupus, we found that CD4(+)Foxp3(+) Treg failed to maintain a competitive pool size in the peripheral lymphoid organs resulting in a progressive homeostatic imbalance of CD4(+)Foxp3(+) Treg and CD4(+)Foxp3(-) conventional T cells (Tcon). In addition, Treg acquired phenotypic changes that are reminiscent of IL-2 deficiency concomitantly to a progressive decline in IL-2-producing Tcon and an increase in activated, IFN-gamma-producing effector Tcon. Nonetheless, Treg from lupus-prone mice were functionally intact and capable to influence the course of disease. Systemic reduction of IL-2 levels early in disease promoted Tcon hyperactivity, induced the imbalance of Treg and effector Tcon, and strongly accelerated disease progression. In contrast, administration of IL-2 partially restored the balance of Treg and effector Tcon by promoting the homeostatic proliferation of endogenous Treg and impeded the progression of established disease. Thus, an acquired and self-amplifying disruption of the Treg-IL-2 axis contributed essentially to Tcon hyperactivity and the development of murine lupus. The reversibility of this homeostatic Treg disorder provides promising approaches for the treatment of SLE.

  11. Phosphorylation of AMPA receptors is required for sensory deprivation-induced homeostatic synaptic plasticity.

    Directory of Open Access Journals (Sweden)

    Anubhuti Goel

    Full Text Available Sensory experience, and the lack thereof, can alter the function of excitatory synapses in the primary sensory cortices. Recent evidence suggests that changes in sensory experience can regulate the synaptic level of Ca(2+-permeable AMPA receptors (CP-AMPARs. However, the molecular mechanisms underlying such a process have not been determined. We found that binocular visual deprivation, which is a well-established in vivo model to produce multiplicative synaptic scaling in visual cortex of juvenile rodents, is accompanied by an increase in the phosphorylation of AMPAR GluR1 (or GluA1 subunit at the serine 845 (S845 site and the appearance of CP-AMPARs at synapses. To address the role of GluR1-S845 in visual deprivation-induced homeostatic synaptic plasticity, we used mice lacking key phosphorylation sites on the GluR1 subunit. We found that mice specifically lacking the GluR1-S845 site (GluR1-S845A mutants, which is a substrate of cAMP-dependent kinase (PKA, show abnormal basal excitatory synaptic transmission and lack visual deprivation-induced homeostatic synaptic plasticity. We also found evidence that increasing GluR1-S845 phosphorylation alone is not sufficient to produce normal multiplicative synaptic scaling. Our study provides concrete evidence that a GluR1 dependent mechanism, especially S845 phosphorylation, is a necessary pre-requisite step for in vivo homeostatic synaptic plasticity.

  12. Phosphorylation of AMPA receptors is required for sensory deprivation-induced homeostatic synaptic plasticity.

    Science.gov (United States)

    Goel, Anubhuti; Xu, Linda W; Snyder, Kevin P; Song, Lihua; Goenaga-Vazquez, Yamila; Megill, Andrea; Takamiya, Kogo; Huganir, Richard L; Lee, Hey-Kyoung

    2011-03-31

    Sensory experience, and the lack thereof, can alter the function of excitatory synapses in the primary sensory cortices. Recent evidence suggests that changes in sensory experience can regulate the synaptic level of Ca(2+)-permeable AMPA receptors (CP-AMPARs). However, the molecular mechanisms underlying such a process have not been determined. We found that binocular visual deprivation, which is a well-established in vivo model to produce multiplicative synaptic scaling in visual cortex of juvenile rodents, is accompanied by an increase in the phosphorylation of AMPAR GluR1 (or GluA1) subunit at the serine 845 (S845) site and the appearance of CP-AMPARs at synapses. To address the role of GluR1-S845 in visual deprivation-induced homeostatic synaptic plasticity, we used mice lacking key phosphorylation sites on the GluR1 subunit. We found that mice specifically lacking the GluR1-S845 site (GluR1-S845A mutants), which is a substrate of cAMP-dependent kinase (PKA), show abnormal basal excitatory synaptic transmission and lack visual deprivation-induced homeostatic synaptic plasticity. We also found evidence that increasing GluR1-S845 phosphorylation alone is not sufficient to produce normal multiplicative synaptic scaling. Our study provides concrete evidence that a GluR1 dependent mechanism, especially S845 phosphorylation, is a necessary pre-requisite step for in vivo homeostatic synaptic plasticity.

  13. Homeostatic imbalance of purine catabolism in first-episode neuroleptic-naive patients with schizophrenia.

    Directory of Open Access Journals (Sweden)

    Jeffrey K Yao

    Full Text Available BACKGROUND: Purine catabolism may be an unappreciated, but important component of the homeostatic response of mitochondria to oxidant stress. Accumulating evidence suggests a pivotal role of oxidative stress in schizophrenia pathology. METHODOLOGY/PRINCIPAL FINDINGS: Using high-pressure liquid chromatography coupled with a coulometric multi-electrode array system, we compared 6 purine metabolites simultaneously in plasma between first-episode neuroleptic-naïve patients with schizophrenia (FENNS, n = 25 and healthy controls (HC, n = 30, as well as between FENNS at baseline (BL and 4 weeks (4w after antipsychotic treatment. Significantly higher levels of xanthosine (Xant and lower levels of guanine (G were seen in both patient groups compared to HC subjects. Moreover, the ratios of G/guanosine (Gr, uric acid (UA/Gr, and UA/Xant were significantly lower, whereas the ratio of Xant/G was significantly higher in FENNS-BL than in HC. Such changes remained in FENNS-4w with exception that the ratio of UA/Gr was normalized. All 3 groups had significant correlations between G and UA, and Xan and hypoxanthine (Hx. By contrast, correlations of UA with each of Xan and Hx, and the correlation of Xan with Gr were all quite significant for the HC but not for the FENNS. Finally, correlations of Gr with each of UA and G were significant for both HC and FENNS-BL but not for the FENNS-4w. CONCLUSIONS/SIGNIFICANCE: During purine catabolism, both conversions of Gr to G and of Xant to Xan are reversible. Decreased ratios of product to precursor suggested a shift favorable to Xant production from Xan, resulting in decreased UA levels in the FENNS. Specifically, the reduced UA/Gr ratio was nearly normalized after 4 weeks of antipsychotic treatment. In addition, there are tightly correlated precursor and product relationships within purine pathways; although some of these correlations persist across disease or medication status, others appear to be lost among FENNS

  14. Sistema de pastejo, rotenona e controle de parasitas em bovinos cruzados: efeito no ganho de peso e no parasitismo Grazing systems, rotenone and parasites control in crossbred calves: effect on live weight gain and on parasites burdens

    Directory of Open Access Journals (Sweden)

    João B. Catto

    2009-12-01

    calves. In the second trial, the effects of grazing systems associated with endo and ectoparasite treatments on parasite burden and weight gain of naturally parasited animals were evaluated. Rotenone showed acaricide action on larvae and engorged ticks during in vitro tests and on larvae in experimentally infected calves. Three treatments with endectocide decreased (P < .05 the number of EPG and ticks and increased (P < .05 the weight gain in the dry season. Animals treated with only one application of levamisole showed EPG intermediate and different (P < .05 from the groups treated with endectocide (lower and control (higher in the dry season, but the weight gain obtained with this treatment did not differ from the control group. During the raining season the animals treated with fipronil were significantly less parasited by horn fly, tick and larvae of Dermatobia hominis and the group treated with rotenone were significantly less parasited by horn fly in relation to control. Animals under rotational grazing showed significantly higher EPG than those under continuous grazing. Three treatments with endectocide in the dry season plus three acaricide treatments with fipronil in the raining season reduced EPG, tick, and screw worm larva counts, and provided a significant increase (23 kg of live weight gain in relation to untreated animals.

  15. Improving mental health of adolescents with Type 1 diabetes: protocol for a randomized controlled trial of the Nothing Ventured Nothing Gained online adolescent and parenting support intervention.

    Science.gov (United States)

    Hackworth, Naomi J; Matthews, Jan; Burke, Kylie; Petrovic, Zvezdana; Klein, Britt; Northam, Elisabeth A; Kyrios, Michael; Chiechomski, Lisa; Cameron, Fergus J

    2013-12-17

    Management of Type 1 diabetes comes with substantial personal and psychological demands particularly during adolescence, placing young people at significant risk for mental health problems. Supportive parenting can mitigate these risks, however the challenges associated with parenting a child with a chronic illness can interfere with a parent's capacity to parent effectively. Interventions that provide support for both the adolescent and their parents are needed to prevent mental health problems in adolescents; to support positive parent-adolescent relationships; and to empower young people to better self-manage their illness. This paper presents the research protocol for a study evaluating the efficacy of the Nothing Ventured Nothing Gained online adolescent and parenting intervention which aims to improve the mental health outcomes of adolescents with Type 1 diabetes. A randomized controlled trial using repeated measures with two arms (intervention and wait-list control) will be used to evaluate the efficacy and acceptability of the online intervention. Approximately 120 adolescents with Type 1 diabetes, aged 13-18 years and one of their parents/guardians will be recruited from pediatric diabetes clinics across Victoria, Australia. Participants will be randomized to receive the intervention immediately or to wait 6 months before accessing the intervention. Adolescent, parent and family outcomes will be assessed via self-report questionnaires at three time points (baseline, 6 weeks and 6 months). The primary outcome is improved adolescent mental health (depression and anxiety). Secondary outcomes include adolescent behavioral (diabetes self-management and risk taking behavior), psychosocial (diabetes relevant quality of life, parent reported child well-being, self-efficacy, resilience, and perceived illness benefits and burdens); metabolic (HbA1c) outcomes; parent psychosocial outcomes (negative affect and fatigue, self-efficacy, and parent experience of child

  16. Comparing gains and losses.

    Science.gov (United States)

    McGraw, A Peter; Larsen, Jeff T; Kahneman, Daniel; Schkade, David

    2010-10-01

    Loss aversion in choice is commonly assumed to arise from the anticipation that losses have a greater effect on feelings than gains, but evidence for this assumption in research on judged feelings is mixed. We argue that loss aversion is present in judged feelings when people compare gains and losses and assess them on a common scale. But many situations in which people judge and express their feelings lack these features. When judging their feelings about an outcome, people naturally consider a context of similar outcomes for comparison (e.g., they consider losses against other losses). This process permits gains and losses to be normed separately and produces psychological scale units that may not be the same in size or meaning for gains and losses. Our experiments show loss aversion in judged feelings for tasks that encourage gain-loss comparisons, but not tasks that discourage them, particularly those using bipolar scales.

  17. EEA1 restores homeostatic synaptic plasticity in hippocampal neurons from Rett syndrome mice.

    Science.gov (United States)

    Xu, Xin; Pozzo-Miller, Lucas

    2017-08-15

    Rett syndrome is a neurodevelopmental disorder caused by loss-of-function mutations in MECP2, the gene encoding the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2). Mecp2 deletion in mice results in an imbalance of excitation and inhibition in hippocampal neurons, which affects 'Hebbian' synaptic plasticity. We show that Mecp2-deficient neurons also lack homeostatic synaptic plasticity, likely due to reduced levels of EEA1, a protein involved in AMPA receptor endocytosis. Expression of EEA1 restored homeostatic synaptic plasticity in Mecp2-deficient neurons, providing novel targets of intervention in Rett syndrome. Rett syndrome is a neurodevelopmental disorder caused by loss-of-function mutations in MECP2, the gene encoding the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2). Deletion of Mecp2 in mice results in an imbalance of synaptic excitation and inhibition in hippocampal pyramidal neurons, which affects 'Hebbian' long-term synaptic plasticity. Since the excitatory-inhibitory balance is maintained by homeostatic mechanisms, we examined the role of MeCP2 in homeostatic synaptic plasticity (HSP) at excitatory synapses. Negative feedback HSP, also known as synaptic scaling, maintains the global synaptic strength of individual neurons in response to sustained alterations in neuronal activity. Hippocampal neurons from Mecp2 knockout (KO) mice do not show the characteristic homeostatic scaling up of the amplitude of miniature excitatory postsynaptic currents (mEPSCs) and of synaptic levels of the GluA1 subunit of AMPA-type glutamate receptors after 48 h silencing with the Na(+) channel blocker tetrodotoxin. This deficit in HSP is bidirectional because Mecp2 KO neurons also failed to scale down mEPSC amplitudes and GluA1 synaptic levels after 48 h blockade of type A GABA receptor (GABAA R)-mediated inhibition with bicuculline. Consistent with the role of synaptic trafficking of AMPA-type of glutamate receptors in HSP, Mecp2 KO neurons

  18. Weight gain as a consequence of living a modern lifestyle: a discussion of barriers to effective weight control and how to overcome them.

    Science.gov (United States)

    Seaman, David R

    2013-12-01

    The purpose of this commentary is to discuss modern lifestyle factors that promote weight gain and to suggest methods for clinicians to more effectively educate patients about weight management. Most adults in the United States are overweight or obese. Multiple factors related to the modern lifestyle appear to play causal roles. In general, the population maintains sedentary lives and overconsumes calorie-dense foods. In particular, refined carbohydrates negatively impact metabolism and stimulate neural addiction mechanisms, which facilitate weight gain. As adipose tissue mass accumulates, satiation centers in the hypothalamus become resistant to insulin and leptin, which leads to increased caloric consumption. Several behavior issues further augment weight gain, such as eating too quickly, a lack of sleep, high stress levels, and a lack of exercise. Finally, adipose tissue accumulation alters the body weight set point, which leads to metabolic changes that function to resist weight loss efforts. Each of these factors may work together to augment weight gain and promote obesity. Health care providers, such as chiropractic physicians, who educate patients on wellness, prevention, and lifestyle changes are well positioned to address these issues. People need to be educated about the modern lifestyle factors that prevent effective weight management. Without this knowledge and the associated practical application of lifestyle choices that prevent weight gain, becoming overweight or obese appears to be an unavoidable consequence of living a modern lifestyle.

  19. Impulse control disorders in Parkinson's disease

    OpenAIRE

    Stacy, Mark

    2009-01-01

    Since the original descriptions of hedonistic homeostatic dysregulation syndrome and pathological gambling in Parkinson's disease, impulse control disorders, such as compulsive spending, punding, or binge eating, are increasingly recognized. Although the term hedonistic homeostatic dysregulation syndrome has been supplanted by the concept of the dopamine dysregulation syndrome, the features of severe dyskinesias, cyclical mood disorder with hypomania or manic psychosis, and impairment of soci...

  20. Insulin resistance as a predictor of gains in body fat, weight, and abdominal fat in nondiabetic women: a prospective study.

    Science.gov (United States)

    Tucker, Larry A; Tucker, Jared M

    2012-07-01

    The purpose was to determine the relationship between insulin resistance (IR) and risk of gaining body fat percentage (BF%), body weight, and abdominal fat over 18 months. A prospective cohort study was conducted using a sample of 226 women. IR was assessed using fasting blood insulin and glucose levels to calculate homeostatic model assessment (HOMA). Participants were divided into High (4th quartile) Moderate (2nd and 3rd quartiles), and Low (1st quartile) HOMA categories. BF% was estimated using plethysmography (Bod Pod), weight was measured in a standard swimsuit, and abdominal fat was indexed using the average of two circumferences taken at the umbilicus. Participants wore accelerometers and completed weighed food logs for 7 consecutive days to control for the effect of physical activity (PA) and energy intake, respectively. On average, women in the High HOMA group decreased in BF% (-0.48 ± 3.60), whereas those in the Moderate (0.40 ± 3.66) and Low HOMA (1.17 ± 3.15) groups gained BF% (F = 5.4, P = 0.0211). Changes in body weight showed a similar dose-response relationship (F = 4.7, P = 0.0317). However, baseline IR was not predictive of changes in abdominal fat (F = 0.8, P = 0.3635). Controlling for several covariates had little effect on gains in BF% and weight, but adjusting for initial BF% and/or initial weight nullified changes in BF% and weight across the IR groups. In conclusion, women with High HOMA tend to gain significantly less BF% and weight than women with low or moderate HOMA. The decreased risk appears unrelated to several covariates, except initial BF% and weight levels, which seem to play key roles in the relationships.

  1. Mini Review: Relational Stability in the Expression of Normality, Variation and Control of Thyroid Function

    Directory of Open Access Journals (Sweden)

    Rudolf Hoermann

    2016-11-01

    Full Text Available Thyroid hormone concentrations only become sufficient to maintain a euthyroid state through appropriate stimulation by pituitary TSH. In such a dynamic system under constant high pressure, guarding against overstimulation becomes vital. Therefore, several defensive mechanisms protect against accidental overstimulation, such as plasma protein binding, conversion of T4 into the more active T3, active transmembrane transport, counter-regulatory activities of reverse T3 and thyronamines and negative hypothalamic-pituitary-thyroid feedback control of TSH. TSH has gained a dominant but misguided role in interpreting thyroid function testing in assuming that its exceptional sensitivity thereby translates into superior diagnostic performance. However, TSH-dependent thyroid disease classification is heavily influenced by statistical analytic techniques such as uni- or multivariate-defined normality. This demands a separation of its conjoint roles as a sensitive screening test and accurate diagnostic tool. Homeostatic equilibria (set points in healthy subjects are less variable, and do not follow a pattern of random variation, rather indicating signs of early and progressive homeostatic control across the euthyroid range. In the event of imminent thyroid failure with a reduced FT4 output per unit TSH, conversion efficiency increases in order to maintain FT3 stability. In such situations, T3 stability takes priority over set point maintenance. This suggests a concept of relational stability. These findings have important implications for both TSH reference limits and treatment targets for patients on levothyroxine. The use of archival markers is proposed to facilitate the homeostatic interpretation of all parameters.

  2. Indoor acoustic gain design

    Science.gov (United States)

    Concha-Abarca, Justo Andres

    2002-11-01

    The design of sound reinforcement systems includes many variables and usually some of these variables are discussed. There are criteria to optimize the performance of the sound reinforcement systems under indoor conditions. The equivalent acoustic distance, the necessary acoustic gain, and the potential acoustic gain are parameters which must be adjusted with respect to the loudspeaker array, electric power and directionality of loudspeakers, the room acoustics conditions, the distance and distribution of the audience, and the type of the original sources. The design and installation of front of the house and monitoring systems have individual criteria. This article is about this criteria and it proposes general considerations for the indoor acoustic gain design.

  3. Higher gestational weight gain is associated with increasing offspring birth weight independent of maternal glycemic control in women with type 1 diabetes

    DEFF Research Database (Denmark)

    Secher, Anna L; Parellada, Clara B; Ringholm, Lene

    2014-01-01

    OBJECTIVE: We evaluate the association between gestational weight gain and offspring birth weight in singleton term pregnancies of women with type 1 diabetes. RESEARCH DESIGN AND METHODS: One hundred fifteen consecutive women referred at ...), and insufficient (n = 16) gestational weight gain. Diabetes duration was comparable, and median prepregnancy BMI was 25.3 (range 18-41) vs. 23.5 (18-31) vs. 22.7 (20-30) kg/m(2) (P = 0.05) in the three weight gain groups. Offspring birth weight and birth weight SD score decreased across the groups (3,681 [2......,374-4,500] vs. 3,395 [2,910-4,322] vs. 3,295 [2,766-4,340] g [P = 0.02] and 1.08 [-1.90 to 3.25] vs. 0.45 [-0.83 to 3.18] vs. -0.02 [-1.51 to 2.96] [P = 0.009], respectively). In a multiple linear regression analysis, gestational weight gain (kg) was positively associated with offspring birth weight (g) (β = 19...

  4. Weight gain - unintentional

    Science.gov (United States)

    ... be due to menstruation, heart or kidney failure, preeclampsia, or medicines you take. A rapid weight gain ... al. Position of the American Dietetic Association: weight management. J Am Diet Assoc . 2009;109:330-46. ...

  5. Estrogen response element-independent signaling partially restores post-ovariectomy body weight gain but is not sufficient for 17β-estradiol's control of energy homeostasis.

    Science.gov (United States)

    Mamounis, Kyle J; Yang, Jennifer A; Yasrebi, Ali; Roepke, Troy A

    2014-03-01

    The steroid 17β-estradiol (E2) modulates energy homeostasis by reducing feeding behavior and increasing energy expenditure primarily through estrogen receptor α (ERα)-mediated mechanisms. Intact ERαKO female mice develop obesity as adults exhibiting decreased energy expenditure and increased fat deposition. However, intact transgenic female mice expressing a DNA-binding-deficient ERα (KIKO) are not obese and have similar energy expenditure, activity and fat deposition as to wild type (WT) females, suggesting that non-estrogen response element (ERE)-mediated signaling is important in E2 regulation of energy homeostasis. Initial reports did not examine the effects of ovariectomy on energy homeostasis or E2's attenuation of post-ovariectomy body weight gain. Therefore, we sought to determine if low physiological doses of E2 (250 ng QOD) known to suppress post-ovariectomy body weight gain in WT females would suppress body weight gain in ovariectomized KIKO females. We observed that the post-ovariectomy increase in body weight was significantly greater in WT females than in KIKO females. Furthermore, E2 did not significantly attenuate the body weight gain in KIKO females as it did in WT females. E2 replacement suppressed food intake and fat accumulation while increasing nighttime oxygen consumption and activity only in WT females. E2 replacement also increased arcuate POMC gene expression in WT females only. These data suggest that in the intact female, ERE-independent mechanisms are sufficient to maintain normal energy homeostasis and to partially restore the normal response to ovariectomy. However, they are not sufficient for E2's suppression of post-ovariectomy body weight gain and its effects on metabolism and activity.

  6. Estrogen response element-independent signaling partially restores post-ovariectomy body weight gain but is not sufficient for 17β-estradiol’s control of energy homeostasis

    Science.gov (United States)

    Mamounis, Kyle J.; Yang, Jennifer A.; Yasrebi, Ali; Roepke, Troy A.

    2013-01-01

    The steroid 17β-estradiol (E2) modulates energy homeostasis by reducing feeding behavior and increasing energy expenditure primarily through estrogen receptor α (ERα)-mediated mechanisms. Intact ERαKO female mice develop obesity as adults exhibiting decreased energy expenditure and increased fat deposition. However, intact transgenic female mice expressing a DNA-binding-deficient ERα (KIKO) are not obese and have similar energy expenditure, activity and fat deposition to wild type (WT) females, suggesting that non-Estrogen Response Element (ERE)-mediated signaling is important in E2 regulation of energy homeostasis. However, initial reports did not examine the effects of ovariectomy on energy homeostasis or E2’s attenuation of post-ovariectomy body weight gain. Therefore, we sought to determine if low physiological doses of E2 (250 ng QOD) known to suppress post-ovariectomy body weight gain in WT females, would suppress body weight gain in ovariectomized KIKO females. We observed that the post-ovariectomy increase in body weight was significantly greater in WT females than in KIKO females. Furthermore, E2 did not significantly attenuate the body weight gain in KIKO females as it did in WT females. E2 replacement suppressed food intake and fat accumulation while increasing nighttime oxygen consumption and activity only in WT females. E2 replacement also increased arcuate POMC gene expression in WT females only. These data suggest that in the intact female, ERE-independent mechanisms are sufficient to maintain normal energy homeostasis and to partially restore the normal response to ovariectomy. However, they are not sufficient for E2’s suppression of post-ovariectomy body weight gain and attenuation of decreases in metabolism and activity. PMID:24252383

  7. A Switching Method for a Model Reference Robust Control with Unknown High Frequency Gain Sign%高频增益符号未知的模型参考鲁棒控制

    Institute of Scientific and Technical Information of China (English)

    袁丽娜; 林岩

    2006-01-01

    The problem of controlling a single-input-single-output plant without prior knowledge of high frequency gain sign is addressed by using the model reference robust control approach. A switching method is proposed based on a monitoring function so that after a finite number of switchings the tracking error converges to zero exponentially. Furthermore, it is shown that if some initial states of the closed-loop system are zero, only one switching is needed.

  8. Association between the insulin-induced gene 2 (INSIG2) and weight gain in a German sample of antipsychotic-treated schizophrenic patients: perturbation of SREBP-controlled lipogenesis in drug-related metabolic adverse effects?

    Science.gov (United States)

    Le Hellard, S; Theisen, F M; Haberhausen, M; Raeder, M B; Fernø, J; Gebhardt, S; Hinney, A; Remschmidt, H; Krieg, J C; Mehler-Wex, C; Nöthen, M M; Hebebrand, J; Steen, V M

    2009-03-01

    Atypical antipsychotics are nowadays the most widely used drugs to treat schizophrenia and other psychosis. Unfortunately, some of them can cause major metabolic adverse effects, such as weight gain, dyslipidemia and type 2 diabetes. The underlying lipogenic mechanisms of the antipsychotic drugs are not known, but several studies have focused on a central effect in the hypothalamic control of appetite regulation and energy expenditure. In a functional convergent genomic approach we recently used a cellular model and demonstrated that orexigenic antipsychotics that induce weight gain activate the expression of lipid biosynthesis genes controlled by the sterol regulatory element-binding protein (SREBP) transcription factors. We therefore hypothesized that the major genes involved in the SREBP activation of fatty acids and cholesterol production (SREBF1, SREBF2, SCAP, INSIG1 and INSIG2) would be strong candidate genes for interindividual variation in drug-induced weight gain. We genotyped a total of 44 HapMap-selected tagging single nucleotide polymorphisms in a sample of 160 German patients with schizophrenia that had been monitored with respect to changes in body mass index during antipsychotic drug treatment. We found a strong association (P=0.0003-0.00007) between three markers localized within or near the INSIG2 gene (rs17587100, rs10490624 and rs17047764) and antipsychotic-related weight gain. Our finding is supported by the recent involvement of the INSIG2 gene in obesity in the general population and implicates SREBP-controlled lipogenesis in drug-induced metabolic adverse effects.

  9. Modeling of Age-Dependent Epileptogenesis by Differential Homeostatic Synaptic Scaling.

    Science.gov (United States)

    González, Oscar C; Krishnan, Giri P; Chauvette, Sylvain; Timofeev, Igor; Sejnowski, Terrence; Bazhenov, Maxim

    2015-09-30

    Homeostatic synaptic plasticity (HSP) has been implicated in the development of hyperexcitability and epileptic seizures following traumatic brain injury (TBI). Our in vivo experimental studies in cats revealed that the severity of TBI-mediated epileptogenesis depends on the age of the animal. To characterize mechanisms of these differences, we studied the properties of the TBI-induced epileptogenesis in a biophysically realistic cortical network model with dynamic ion concentrations. After deafferentation, which was induced by dissection of the afferent inputs, there was a reduction of the network activity and upregulation of excitatory connections leading to spontaneous spike-and-wave type seizures. When axonal sprouting was implemented, the seizure threshold increased in the model of young but not the older animals, which had slower or unidirectional homeostatic processes. Our study suggests that age-related changes in the HSP mechanisms are sufficient to explain the difference in the likelihood of seizure onset in young versus older animals. Significance statement: Traumatic brain injury (TBI) is one of the leading causes of intractable epilepsy. Likelihood of developing epilepsy and seizures following severe brain trauma has been shown to increase with age. Specific mechanisms of TBI-related epileptogenesis and how these mechanisms are affected by age remain to be understood. We test a hypothesis that the failure of homeostatic synaptic regulation, a slow negative feedback mechanism that maintains neural activity within a physiological range through activity-dependent modulation of synaptic strength, in older animals may augment TBI-induced epileptogenesis. Our results provide new insight into understanding this debilitating disorder and may lead to novel avenues for the development of effective treatments of TBI-induced epilepsy.

  10. The core and conserved role of MAL is homeostatic regulation of actin levels.

    Science.gov (United States)

    Salvany, Lara; Muller, Julius; Guccione, Ernesto; Rørth, Pernille

    2014-05-15

    The transcription cofactor MAL is regulated by free actin levels and thus by actin dynamics. MAL, together with its DNA-binding partner, SRF, is required for invasive cell migration and in experimental metastasis. Although MAL/SRF has many targets, we provide genetic evidence in both Drosophila and human cellular models that actin is the key target that must be regulated by MAL/SRF for invasive cell migration. By regulating MAL/SRF activity, actin protein feeds back on production of actin mRNA to ensure sufficient supply of actin. This constitutes a dedicated homeostatic feedback system that provides a foundation for cellular actin dynamics.

  11. Homeostatic regulation of sleep in the white-crowned sparrow (Zonotrichia leucophrys gambelii

    Directory of Open Access Journals (Sweden)

    Cirelli Chiara

    2008-05-01

    Full Text Available Abstract Background Sleep is regulated by both a circadian and a homeostatic process. The homeostatic process reflects the duration of prior wakefulness: the longer one stays awake, the longer and/or more intense is subsequent sleep. In mammals, the best marker of the homeostatic sleep drive is slow wave activity (SWA, the electroencephalographic (EEG power spectrum in the 0.5–4 Hz frequency range during non-rapid eye movement (NREM sleep. In mammals, NREM sleep SWA is high at sleep onset, when sleep pressure is high, and decreases progressively to reach low levels in late sleep. Moreover, SWA increases further with sleep deprivation, when sleep also becomes less fragmented (the duration of sleep episodes increases, and the number of brief awakenings decreases. Although avian and mammalian sleep share several features, the evidence of a clear homeostatic response to sleep loss has been conflicting in the few avian species studied so far. The aim of the current study was therefore to ascertain whether established markers of sleep homeostasis in mammals are also present in the white-crowned sparrow (Zonotrichia leucophrys gambelii, a migratory songbird of the order Passeriformes. To accomplish this goal, we investigated amount of sleep, sleep time course, and measures of sleep intensity in 6 birds during baseline sleep and during recovery sleep following 6 hours of sleep deprivation. Results Continuous (24 hours EEG and video recordings were used to measure baseline sleep and recovery sleep following short-term sleep deprivation. Sleep stages were scored visually based on 4-sec epochs. EEG power spectra (0.5–25 Hz were calculated on consecutive 4-sec epochs. Four vigilance states were reliably distinguished based on behavior, visual inspection of the EEG, and spectral EEG analysis: Wakefulness (W, Drowsiness (D, slow wave sleep (SWS and rapid-eye movement (REM sleep. During baseline, SWA during D, SWS, and NREM sleep (defined as D and SWS

  12. A leech model for homeostatic plasticity and motor network recovery after loss of descending inputs.

    Science.gov (United States)

    Lane, Brian J

    2016-04-01

    Motor networks below the site of spinal cord injury (SCI) and their reconfiguration after loss of central inputs are poorly understood but remain of great interest in SCI research. Harley et al. (J Neurophysiol 113: 3610-3622, 2015) report a striking locomotor recovery paradigm in the leech Hirudo verbena with features that are functionally analogous to SCI. They propose that this well-established neurophysiological system could potentially be repurposed to provide a complementary model to investigate basic principles of homeostatic compensation relevant to SCI research.

  13. Homeostasis and change: A commentary on Homeostatic Theory of Obesity by David Marks

    Directory of Open Access Journals (Sweden)

    Carlo C DiClemente

    2016-03-01

    Full Text Available This commentary on David Marks’ article on the Homeostatic Theory of Obesity and his Circle of Discontent mechanism for maintaining problematic eating behavior and obesity offers a perspective on the promise and potential of this theory. At the same time, we challenge the author to incorporate more of a process perspective into the theory. This would include greater exploration of how individuals enter and exit this hypothesized Circle of Discontent, how these mechanisms lead to obesity rather than other internalizing or externalizing disorders, and how the interactions among key variables differ for males and females and developmental stages.

  14. Weight gain as a consequence of living a modern lifestyle: a discussion of barriers to effective weight control and how to overcome them

    OpenAIRE

    Seaman, David R

    2013-01-01

    Objective The purpose of this commentary is to discuss modern lifestyle factors that promote weight gain and to suggest methods for clinicians to more effectively educate patients about weight management. Discussion Most adults in the United States are overweight or obese. Multiple factors related to the modern lifestyle appear to play causal roles. In general, the population maintains sedentary lives and overconsumes calorie-dense foods. In particular, refined carbohydrates negatively impact...

  15. Integrating the cell stress response: a new view of molecular chaperones as immunological and physiological homeostatic regulators.

    Science.gov (United States)

    Henderson, Brian

    2010-01-01

    The response of cells to stress was first documented in the 1960s and 1970s and the molecular nature of the families of proteins that subserve this vital response, the molecular chaperones, were identified and subjected to critical study in the period from the late 1980s. This resulted in the rapidly advancing new field of protein folding and its role in cellular function. Emerging at the same time, but initially largely ignored, were reports that molecular chaperones could be released by cells and exist on the outer plasma membrane or in the body fluids. These secreted molecular chaperones were found to have intercellular signalling functions. There is now a growing body of evidence to support the hypothesis that molecular chaperones have properties ascribed to the Roman god Janus, the god of gates, doors, beginnings and endings, whose two faces point in different directions. Molecular chaperones appear to have one set of key functions within the cell and, potentially, a separate set of functions when they exist on the cell surface or in the various fluid phases of the body. Thus, it is a likely hypothesis that secreted molecular chaperones act as an additional level of homeostatic control possibly linking cellular stress to physiological systems such as the immune system. This review concentrates on three key molecular chaperones: Hsp10, Hsp60 and the Hsp70 family for which most information is available. An important consideration is the role that these proteins may play in human disease and in the treatment of human disease.

  16. B cell development in the bone marrow is regulated by homeostatic feedback exerted by mature B cells

    Directory of Open Access Journals (Sweden)

    Gitit eShahaf

    2016-03-01

    Full Text Available Cellular homeostasis in the B cell compartment is strictly imposed to balance cell production and cell loss. However, it is not clear whether B cell development in the bone marrow (BM is an autonomous process or subjected to regulation by the peripheral B cell compartment. To specifically address this question, we used mice transgenic for human CD20, where effective depletion of B lineage cells is obtained upon administration of mouse-anti-human CD20 antibodies, in the absence of any effect on other cell lineages and/or tissues. We followed the kinetics of B cell return to equilibrium by BrdU labeling and flow cytometry and analyzed the resulting data by mathematical modeling. Labeling was much faster in depleted mice. Compared to control mice, B cell-depleted mice exhibited a higher proliferation rate in the pro-/pre-B compartment, and higher cell death and lower differentiation in the immature B cell compartment. We validated the first result by analysis of the expression of Ki67, the nuclear protein expressed in proliferating cells, and the second using Annexin-V staining. Collectively, our results suggest that B lymphopoiesis is subjected to homeostatic feedback mechanisms imposed by mature B cells in the peripheral compartment.

  17. Critical role of quorum sensing-dependent glutamate metabolism in homeostatic osmolality and outer membrane vesiculation in Burkholderia glumae

    Science.gov (United States)

    Kang, Yongsung; Goo, Eunhye; Kim, Jinwoo; Hwang, Ingyu

    2017-01-01

    Metabolic homeostasis in cooperative bacteria is achieved by modulating primary metabolism in a quorum sensing (QS)-dependent manner. A perturbed metabolism in QS mutants causes physiological stress in the rice bacterial pathogen Burkholderia glumae. Here, we show that increased bacterial osmolality in B. glumae is caused by unusually high cellular concentrations of glutamate and betaine generated by QS deficiencies. QS negatively controls glutamate uptake and the expression of genes involved in the glutamine synthetase and glutamine oxoglutarate aminotransferase cycles. Thus, cellular glutamate levels were significantly higher in the QS mutants than in the wild type, and they caused hyperosmotic cellular conditions. Under the hypotonic conditions of the periplasm in the QS mutants, outer membrane bulging and vesiculation were observed, although these changes were rescued by knocking out the gltI gene, which encodes a glutamate transporter. Outer membrane modifications were not detected in the wild type. These results suggest that QS-dependent glutamate metabolism is critical for homeostatic osmolality. We suggest that outer membrane bulging and vesiculation might be the outcome of a physiological adaptation to relieve hypotonic osmotic stress in QS mutants. Our findings reveal how QS functions to maintain bacterial osmolality in a cooperative population. PMID:28272446

  18. Gain scheduling using the youla parameterization

    DEFF Research Database (Denmark)

    Niemann, H.H.; Stoustrup, Jakob

    1999-01-01

    Gain scheduling controllers are considered in this paper. The gain scheduling problem where the scheduling parameter vector theta cannot be measured directly, but needs to be estimated is considered. An estimation of the scheduling vector theta has been derived by using the Youla parameterization...

  19. 一种dB线性数字控制可变增益放大器的设计%Design of a dB-Linear Digitally-Controlled Variable Gain Amplifier

    Institute of Scientific and Technical Information of China (English)

    杨骁; 齐骋; 黄炜炜; 凌朝东

    2012-01-01

    A decibel-linear digitally-controlled variable gain amplifier (VGA) was designed based on common-source amplifier with diode-connected load. The gain of the amplifier was controlled by simultaneously changing bias current ratio and transistor size ratio, which made current density of input/diode-connected transistors stay constant with gain variation and achieved significant improvement in linearity at low gains. The circuit was designed in NEC 0. 35-μm CMOS process. Simulation results showed that the circuit had a dB-linear gain ranging from -11. 85 dB to 11. 64 dB with gain error less than 0. 5 dB, a 1-dB compression point of 8. 35 dBm for gain setting of -11. 85 dB, and a -3 dB bandwidth above 62 MHz, which may vary between 62 MHz and 240 MHz depending on gain setting.%设计了一种dB线性增益的数字控制可变增益放大器.以二极管做负载的全差分输入共源极放大器为原型,通过同时同比例地改变输入输出晶体管尺寸比和偏置电流比来控制增益变化,使输入输出晶体管的电流密度保持一恒定值,提高了电路在低增益时的线性度.电路采用NEC 0.35 μm CMOS标准工艺库进行设计.仿真结果表明,dB线性增益范围为-11.85 dB到11.64 dB,增益误差小于0.5 dB.增益为-11.85 dB时,其1-dB压缩点达到8.35 dBm,-3 dB增益带宽大于62 MHz,并且随设定的增益值在62 MHz和240 MHz之间变化.

  20. Relational Information Gain

    DEFF Research Database (Denmark)

    Lippi, Marco; Jaeger, Manfred; Frasconi, Paolo

    2011-01-01

    We introduce relational information gain, a refinement scoring function measuring the informativeness of newly introduced variables. The gain can be interpreted as a conditional entropy in a well-defined sense and can be efficiently approximately computed. In conjunction with simple greedy general......-to-specific search algorithms such as FOIL, it yields an efficient and competitive algorithm in terms of predictive accuracy and compactness of the learned theory. In conjunction with the decision tree learner TILDE, it offers a beneficial alternative to lookahead, achieving similar performance while significantly...

  1. A phosphatase-independent gain-of-function mutation in PTEN triggers aberrant cell growth in astrocytes through an autocrine IGF-1 loop.

    Science.gov (United States)

    Fernández, S; Genis, L; Torres-Alemán, I

    2014-08-07

    Loss-of-function mutations in the phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome10) contribute to aberrant cell growth in part through upregulation of the mitogenic IGF-1/PI3K/Akt pathway. In turn, this pathway exerts a homeostatic feedback over PTEN. Using mutagenesis analysis to explore a possible impact of this mutual control on astrocyte growth, we found that truncation of the C-terminal region of PTEN (Δ51) associates with a marked increase in NFκB activity, a transcription factor overactivated in astrocyte tumors. Whereas mutations of PTEN are considered to lead to a loss-of-function, PTENΔ51, a truncation that comprises a region frequently mutated in human gliomas, displayed a neomorphic (gain-of-function) activity that was independent of its phosphatase activity. This gain-of-function of PTENΔ51 includes stimulation of IGF-1 synthesis through protein kinase A activation of the IGF-1 promoter. Increased IGF-1 originates an autocrine loop that activates Akt and NFκB. Constitutive activation of NFκB in PTENΔ51-expressing astrocytes leads to aberrant cell growth; astrocytes expressing this mutant PTEN generate colonies in vitro and tumors in vivo. Mutations converting a tumor suppressor such as PTEN into a tumor promoter through a gain-of-function involving IGF-1 production may further our understanding of the role played by this growth factor in glioma growth and help us define druggable targets for personalized therapy.

  2. Geometry and dynamics of activity-dependent homeostatic regulation in neurons.

    Science.gov (United States)

    Olypher, Andrey V; Prinz, Astrid A

    2010-06-01

    To maintain activity in a functional range, neurons constantly adjust membrane excitability to changing intra- and extracellular conditions. Such activity-dependent homeostatic regulation (ADHR) is critical for normal processing of the nervous system and avoiding pathological conditions. Here, we posed a homeostatic regulation problem for the classical Morris-Lecar (ML) model. The problem was motivated by the phenomenon of the functional recovery of stomatogastric neurons in crustaceans in the absence of neuromodulation. In our study, the regulation of the ionic conductances in the ML model depended on the calcium current or the intracellular calcium concentration. We found an asymptotic solution to the problem under the assumption of slow regulation. The solution provides a full account of the regulation in the case of correlated or anticorrelated changes of the maximal conductances of the calcium and potassium currents. In particular, the solution shows how the target and parameters of the regulation determine which perturbations of the conductances can be compensated by the ADHR. In some cases, the sets of compensated initial perturbations are not convex. On the basis of our analysis we formulated specific questions for subsequent experimental and theoretical studies of ADHR.

  3. Bassoon-disruption slows vesicle replenishment and induces homeostatic plasticity at a CNS synapse.

    Science.gov (United States)

    Mendoza Schulz, Alejandro; Jing, Zhizi; Sánchez Caro, Juan María; Wetzel, Friederike; Dresbach, Thomas; Strenzke, Nicola; Wichmann, Carolin; Moser, Tobias

    2014-03-03

    Endbulb of Held terminals of auditory nerve fibers (ANF) transmit auditory information at hundreds per second to bushy cells (BCs) in the anteroventral cochlear nucleus (AVCN). Here, we studied the structure and function of endbulb synapses in mice that lack the presynaptic scaffold bassoon and exhibit reduced ANF input into the AVCN. Endbulb terminals and active zones were normal in number and vesicle complement. Postsynaptic densities, quantal size and vesicular release probability were increased while vesicle replenishment and the standing pool of readily releasable vesicles were reduced. These opposing effects canceled each other out for the first evoked EPSC, which showed unaltered amplitude. We propose that ANF activity deprivation drives homeostatic plasticity in the AVCN involving synaptic upscaling and increased intrinsic BC excitability. In vivo recordings from individual mutant BCs demonstrated a slightly improved response at sound onset compared to ANF, likely reflecting the combined effects of ANF convergence and homeostatic plasticity. Further, we conclude that bassoon promotes vesicular replenishment and, consequently, a large standing pool of readily releasable synaptic vesicles at the endbulb synapse.

  4. Zinc transport complexes contribute to the homeostatic maintenance of secretory pathway function in vertebrate cells.

    Science.gov (United States)

    Ishihara, Kaori; Yamazaki, Tomohiro; Ishida, Yoko; Suzuki, Tomoyuki; Oda, Kimimitsu; Nagao, Masaya; Yamaguchi-Iwai, Yuko; Kambe, Taiho

    2006-06-30

    Zinc transporters play important roles in a wide range of biochemical processes. Here we report an important function of ZnT5/ZnT6 hetero-oligomeric complexes in the secretory pathway. The activity of human tissue-nonspecific alkaline phosphatase (ALP) expressed in ZnT5(-)ZnT7(-/-) cells was significantly reduced compared with that expressed in wild-type cells as in the case of endogenous chicken tissue-nonspecific ALP activity. The inactive human tissue-nonspecific ALP in ZnT5(-)ZnT7(-/-) cells was degraded by proteasome-mediated degradation without being trafficked to the plasma membrane. ZnT5(-)ZnT7(-/-) cells showed exacerbation of the unfolded protein response as did the wild-type cells cultured under a zinc-deficient condition, revealing that both complexes play a role in homeostatic maintenance of secretory pathway function. Furthermore, we showed that expression of ZnT5 mRNA was up-regulated by the endoplasmic reticulum stress in various cell lines. The up-regulation of the hZnT5 transcript was mediated by transcription factor XBP1 through the TGACGTGG sequence in the hZnT5 promoter, and this sequence was highly conserved in the ZnT5 genes of mouse and chicken. These results suggest that zinc transport into the secretory pathway is strictly regulated for the homeostatic maintenance of secretory pathway function in vertebrate cells.

  5. Should I Gain Weight?

    Science.gov (United States)

    ... If you're having trouble with your body image, talk about how you feel with someone you like and trust who's been through it — maybe a parent, doctor, counselor, coach, or teacher. continue It's the Growth, Not the Gain No ...

  6. Tradeoff on gain-flatness and gain-stabilization of erbium doped fiber amplifier with FBGs

    Science.gov (United States)

    Buyin, Garidi; OuYang, Yunlun; Ma, Yu; Chang, Jinlong; Liu, Changxing; Yang, Jiuru

    2014-07-01

    It is a challenge to get gain-stabilization and gain-flatness of erbium doped fiber amplifier (EDFA) in C-band, simultaneously. In this article, we establish a gain-clamped EDFA model based uniform fiber grating-pair and optimize the reflectivity of grating by the designed targets. The tradeoff between stabilization and flatness can be obtained when an ideal reflectivity is adopted. The numerical results show that the gain-stabilization is controlled in +/-0.1dB and gain-flatness is less than +/-1.41dB in the range from 1535nm to 1565nm.

  7. Gain control for solar wall heating with transparent insulation (TI) - requirements for cost effective application of natural ventilation in multifunctional and ventilated facades (MFVF)

    Energy Technology Data Exchange (ETDEWEB)

    Haller, A.; Althaus, H.J. [Ernst Schweizer AG, Hedingen (Switzerland); Platzer, W.J. [Fraunhofer Inst. for Solar Energy Systems, ISE, Freiburg (Germany); Goerdt, W. [PSE Projektgesellschaft Solare Energiesysteme mbH, Freiburg (Germany)

    2000-07-01

    This paper describes the potential of natural ventilation for solar wall heating systems with TI in order to avoid overheating in summer. Based on a commercial facade system two prototypes have been built with different absorber characteristics. The measurements on a outdoor test site showed that it is possible to reach an equivalent energy transmission value (g-value) as low as 15% in ventilated mode. In heating mode with sealed ventilation cavity the g-value reaches 48%. With a lime stone mass wall this yields to a system efficiency of 36% and an U-value below 1 W/m{sup 2}K. The variation of the absorber characteristics showed that is possible to reach higher solar gains in winter at the cost of higher g-values in summer. The optimum depends on the application and its tolerance to summer heat gains. The experiments did also confirm the demanding requirements for the ventilation valve construction in closed state: 140 deg. C maximum operating temperature, U-value of 1 W/m{sup 2}K, air tightness comparable to a low energy window. In ventilation state, a open area of 600 dm{sup 2} per meter width with low pressure drop is required. Unfortunately no systems or products are commercially available to fulfil these requirements. Thus, three concepts were further investigated for this application. Test showed that there will be more development and investment required for a commercial facade product. (au)

  8. 一种低电压、低噪声、低失真度的语音信号自动增益控制电路%A Low Noise Low Distortion Automatic Gain Control Circuit

    Institute of Scientific and Technical Information of China (English)

    王明轩; 李冬梅

    2016-01-01

    This paper presents a kind of Automatic Gain Control (AGC)circuits which can be used in speech signal acquisition system,it has high gain range,low noise and high linearity.The proposed AGC is based on feedback topologies and the gain is digital controlled.The design indexes are 1 V supply voltage,0~40 dB gain range,2 dB gain step,8 kHz bandwidth.Aπ-type resistors network is used in the Programmable Gain Amplifier (PGA)as the passive feedback device to realize gain linearity in decibels and increase the gain accuracy.The hysteresis comparator eliminate the chattering effects when the output signal of Peak Detector changes rapidly around the threshold.The design is implemented in 0.18μm CMOS and occupies an active area of 0.41 mm2 .The power consumption of AGC is about 0.17 mW at 1 V supply voltage.The gain of AGC loop ranges from 0 dB to 40.2 dB in 2 dB step with gain error not more than 0.2 dB.The total harmonic distortion (THD)is below-70 dB over the audio frequencies at 1 kHz,0.4-Vpp differential output.The integrated noise in the audio range (20 Hz~20 kHz)is less than 5μVRMS when the gain of PGA is set at 0 dB.%提出了一种工作在低电压下的宽动态范围、低噪声、低失真度的可用于语音信号采集系统的自动增益控制电路(AGC).该AGC环路采用反馈式结构,数字式增益控制.设计指标为1 V工作电压,0~40 dB增益动态范围,2 dB增益步长,8 kHz带宽.采用π型电阻网络作为环路中可变增益放大器的无源反馈网络,提高增益的准确性并实现增益在对数单位下的线性.采用滞回比较器来减弱当峰值检测器输出信号在阈值电压附近小幅度快速变化而引起的抖动.基于UMC180 nm CMOS工艺完成电路及版图设计,芯片面积约为0.45 mm2.提取版图寄生参数后的电路仿真结果显示,AGC环路的功耗在1 V工作电压下约为0.17 mW;AGC的增益动态范围为0~40.2 dB,增益步长为2 d

  9. Neural pathways controlling homeostatic and hedonic feeding in rats on free-choice diets

    NARCIS (Netherlands)

    van den Heuvel, J.K.

    2014-01-01

    The incidence of obesity is closely associated with the increased intake of saturated fat and sugar-sweetened beverages, however the mechanisms that regulate the consumption of dietary fat and sugared beverages remain to be determined. We used a novel animal model of obesity that closely resembles t

  10. Neural pathways controlling homeostatic and hedonic feeding in rats on free-choice diets

    NARCIS (Netherlands)

    van den Heuvel, J.K.

    2014-01-01

    The incidence of obesity is closely associated with the increased intake of saturated fat and sugar-sweetened beverages, however the mechanisms that regulate the consumption of dietary fat and sugared beverages remain to be determined. We used a novel animal model of obesity that closely resembles

  11. Control of Rubisco function via homeostatic equilibration of CO2 supply

    Directory of Open Access Journals (Sweden)

    Abir U Igamberdiev

    2015-02-01

    Full Text Available Rubisco is the most abundant protein on Earth that serves as the primary engine of carbon assimilation. It is characterized by a slow rate and low specificity for CO2 leading to photorespiration. We analyze here the challenges of operation of this enzyme as the main carbon fixation engine. The high concentration of Rubisco exceeds that of its substrate CO2 by 2–3 orders of magnitude; however, the total pool of available carbon in chloroplast, i.e. mainly bicarbonate, is comparable to the concentration of Rubisco active sites. This makes the reactant stationary assumption (RSA, which is essential as a condition of satisfying the Michaelis-Menten (MM kinetics, valid if we assume that the delivery of CO2 from this pool is not limiting. The RSA is supported by active carbonic anhydrases (CA that quickly equilibrate bicarbonate and CO2 pools and supply CO2 to Rubisco. While the operation of stromal CA is independent of light reactions, the thylakoidal CA associated with PSII and pumping CO2 from the thylakoid lumen is coordinated with the rate of electron transport, water splitting and proton gradient across the thylakoid membrane. At high CO2 concentrations, CA becomes less efficient (the equilibrium becomes unfavourable, so a deviation from the MM kinetics is observed, consistent with Rubisco reaching its Vmax at approximately 50% lower level than expected from the classical MM curve. Previously, this deviation was controversially explained by the limitation of RuBP regeneration. At low ambient CO2 and correspondingly limited capacity of the bicarbonate pool, its depletion at Rubisco sites is relieved in that the enzyme utilizes O2 instead of CO2, i.e. by photorespiration. In this process, CO2 is supplied back to Rubisco, and the chloroplastic redox state and energy level are maintained. It is concluded that the optimal performance of photosynthesis is achieved via the provision of continuous CO2 supply to Rubisco by carbonic anhydrases and photorespiration.

  12. The homeostatic regulation of REM sleep: A role for localized expression of brain-derived neurotrophic factor in the brainstem.

    Science.gov (United States)

    Datta, Subimal; Knapp, Clifford M; Koul-Tiwari, Richa; Barnes, Abigail

    2015-10-01

    Homeostatic regulation of REM sleep plays a key role in neural plasticity and deficits in this process are implicated in the development of many neuropsychiatric disorders. Little is known, however, about the molecular mechanisms that underlie this homeostatic regulation process. This study examined the hypothesis that, during selective REM sleep deprivation (RSD), increased brain-derived neurotrophic factor (BDNF) expression in REM sleep regulating areas is critical for the development of homeostatic drive for REM sleep, as measured by an increase in the number of REM sleep transitions. Rats were assigned to RSD, non-sleep deprived (BSL), or total sleep deprivation (TSD) groups. Physiological recordings were obtained from cortical, hippocampal, and pontine EEG electrodes over a 6h period, in which sleep deprivation occurred during the first 3h. In the RSD, but not the other conditions, homeostatic drive for REM sleep increased progressively. BDNF protein expression was significantly greater in the pedunculopontine tegmentum (PPT) and subcoeruleus nucleus (SubCD) in the RSD as compared to the TSD and BSL groups, areas that regulate REM sleep, but not in the medial preoptic area, which regulates non-REM sleep. There was a significant positive correlation between RSD-induced increases in number of REM sleep episodes and increased BDNF expression in the PPT and SubCD. These increases positively correlated with levels of homeostatic drive for REM sleep. These results, for the first time, suggest that selective RSD-induced increased expression of BDNF in the PPT and SubCD are determinant factors in the development of the homeostatic drive for REM sleep.

  13. Extract of Irish potatoes (Solanum tuberosum L.) decreases body weight gain and adiposity and improves glucose control in the mouse model of diet-induced obesity.

    Science.gov (United States)

    Kubow, Stan; Hobson, Luc; Iskandar, Michèle M; Sabally, Kebba; Donnelly, Danielle J; Agellon, Luis B

    2014-11-01

    Both sexes of mice were fed a high fat diet (HFD) for 10 weeks without and with polyphenolic-rich potato extracts (PRPE) of cultivars Onaway and Russet Burbank. PRPE attenuated weight gain in male and female mice by as much as 63.2%, which was associated mostly with a reduction in adiposity. Mice receiving PRPE showed enhanced capacity for blood glucose clearance. Sex differences regarding the impact of HFD and PRPE on plasma levels of insulin, ghrelin, leptin, gastric inhibitory peptide, and resistin were noted. PRPE may serve as part of a preventative dietary strategy against the development of obesity and type 2 diabetes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Gaining Relational Competitive Advantages

    DEFF Research Database (Denmark)

    Hu, Yimei; Zhang, Si; Li, Jizhen

    2015-01-01

    Establishing strategic technological partnerships (STPs) with foreign partners is an increasingly studied topic within the innovation management literature. Partnering firms can jointly create sources of relational competitive advantage. Chinese firms often lack research and development (R......&D) capabilities but are increasingly becoming preferred technological partners for transnational corporations. We investigate an STP between a Scandinavian and a Chinese firm and try to explore how to gain relational competitive advantage by focusing on its two essential stages: relational rent generation...

  15. Learn and gain

    CERN Document Server

    Al-Alami, Suhair Eyad Jamal

    2013-01-01

    Initiating the slogan ""love it, live it"", Learn and Gain includes eight short stories, chosen to illustrate various modes of narration, as well as to provoke reflection and discussion on a range of issues. All texts utilized here illustrate how great writers can, with their insight and gift for words, help us to see the world we live in, in new probing and exciting ways. What characterises the book, the author believes, is the integration of the skills of literary competence, communicative c...

  16. 大型土建工程管理中成本控制增益均衡模型%The Cost Control Gain Equilibrium Model of The Large Civil Engineering Management

    Institute of Scientific and Technical Information of China (English)

    胡晓娟

    2015-01-01

    The increased cost of construction. For this, put forward a large civil engineering management cost control gain equilibrium model, using the data from the civil engineering construction of construction cost estimates, cost control gain balance model is established, through the forecast data and actual cost error gain balance calculation, the process of the project cost control for minimum error value. The simulation experiment indicates that the gain equalization algorithm can effectively improve the efficiency of soil construction cost management, reduce the error of cost management at the same time, with the most effective the most reasonable method, to budget, cost effective for the management of civil engineering to provide better protection.%提出大型土建工程管理中成本控制增益均衡模型,利用土建工程相关施工数据,对施工建设做成本预估,建立成本控制增益均衡模型,通过预估数据与实际成本误差进行增益均衡计算,使工程成本控制得到最小误差值的过程.仿真试验表明,这种增益均衡算法更能有效的提高土建工成本管理的效率,同时降低成本管理的误差,以最有效最合理的方法,对成本进行预算,有效的为土建工程的管理提供更好的保障.

  17. Homeostatic regulation of the PI(4,5)P2-Ca(2+) signaling system at ER-PM junctions.

    Science.gov (United States)

    Chang, Chi-Lun; Liou, Jen

    2016-08-01

    The phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2)-Ca(2+) signaling system is important for cell activation in response to various extracellular stimuli. This signaling system is initiated by receptor-induced hydrolysis of PI(4,5)P2 in the plasma membrane (PM) to generate the soluble second messenger inositol 1,4,5-trisphosphate (IP3). IP3 subsequently triggers the release of Ca(2+) from the endoplasmic reticulum (ER) store to the cytosol to activate Ca(2+)-mediated responses, such as secretion and proliferation. The consumed PM PI(4,5)P2 and ER Ca(2+) must be quickly restored to sustain signaling responses, and to maintain the homeostasis of PI(4,5)P2 and Ca(2+). Since phosphatidylinositol (PI), the precursor lipid for PM PI(4,5)P2, is synthesized in the ER membrane, and a Ca(2+) influx across the PM is required to refill the ER Ca(2+) store, efficient communications between the ER and the PM are critical for the homeostatic regulation of the PI(4,5)P2-Ca(2+) signaling system. This review describes the major findings that established the framework of the PI(4,5)P2-Ca(2+) signaling system, and recent discoveries on feedback control mechanisms at ER-PM junctions that sustain the PI(4,5)P2-Ca(2+) signaling system. Particular emphasis is placed on the characterization of ER-PM junctions where efficient communications between the ER and the PM occur, and the activation mechanisms of proteins that dynamically localize to ER-PM junctions to provide the feedback control during PI(4,5)P2-Ca(2+) signaling, including the ER Ca(2+) sensor STIM1, the extended synaptotagmin E-Syt1, and the PI transfer protein Nir2. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.

  18. Biomimetic emulsions reveal the effect of homeostatic pressure on cell-cell adhesion

    CERN Document Server

    Pontani, Lea-Laetitia; Viasnoff, Virgile; Brujic, Jasna

    2012-01-01

    Cell-cell contacts in tissues are continuously subject to mechanical forces due to homeostatic pressure and active cytoskeleton dynamics. While much is known about the molecular pathways of adhesion, the role of mechanics is less well understood. To isolate the role of pressure we present a dense packing of functionalized emulsion droplets in which surface interactions are tuned to mimic those of real cells. By visualizing the microstructure in 3D we find that a threshold compression force is necessary to overcome electrostatic repulsion and surface elasticity and establish protein-mediated adhesion. Varying the droplet interaction potential maps out a phase diagram for adhesion as a function of force and salt concentration. Remarkably, fitting the data with our theoretical model predicts binder concentrations in the adhesion areas that are similar to those found in real cells. Moreover, we quantify the adhesion size dependence on the applied force and thus reveal adhesion strengthening with increasing homeos...

  19. Diversity and noise effects in a model of homeostatic regulation of the sleep-wake cycle

    CERN Document Server

    Patriarca, Marco; Braun, Hans A; Hernández-García, Emilio; Toral, Raúl; 10.1371/journal.pcbi.1002650

    2012-01-01

    Recent advances in sleep neurobiology have allowed development of physiologically based mathematical models of sleep regulation that account for the neuronal dynamics responsible for the regulation of sleep-wake cycles and allow detailed examination of the underlying mechanisms. Neuronal systems in general, and those involved in sleep regulation in particular, are noisy and heterogeneous by their nature. It has been shown in various systems that certain levels of noise and diversity can significantly improve signal encoding. However, these phenomena, especially the effects of diversity, are rarely considered in the models of sleep regulation. The present paper is focused on a neuron-based physiologically motivated model of sleep-wake cycles that proposes a novel mechanism of the homeostatic regulation of sleep based on the dynamics of a wake-promoting neuropeptide orexin. Here this model is generalized by the introduction of intrinsic diversity and noise in the orexin-producing neurons in order to study the e...

  20. Homeostatic regulation of supercoiling sensitivity coordinates transcription of the bacterial genome.

    Science.gov (United States)

    Blot, Nicolas; Mavathur, Ramesh; Geertz, Marcel; Travers, Andrew; Muskhelishvili, Georgi

    2006-07-01

    Regulation of cellular growth implies spatiotemporally coordinated programmes of gene transcription. A central question, therefore, is how global transcription is coordinated in the genome. The growth of the unicellular organism Escherichia coli is associated with changes in both the global superhelicity modulated by cellular topoisomerase activity and the relative proportions of the abundant DNA-architectural chromatin proteins. Using a DNA-microarray-based approach that combines mutations in the genes of two important chromatin proteins with induced changes of DNA superhelicity, we demonstrate that genomic transcription is tightly associated with the spatial distribution of supercoiling sensitivity, which in turn depends on chromatin proteins. We further demonstrate that essential metabolic pathways involved in the maintenance of growth respond distinctly to changes of superhelicity. We infer that a homeostatic mechanism organizing the supercoiling sensitivity is coordinating the growth-phase-dependent transcription of the genome.

  1. Fortification of immune and homeostatic surveillance in cancer-like and cancer conditions the natural way

    Directory of Open Access Journals (Sweden)

    Simon Vassiliadis

    2015-10-01

    Full Text Available Background: Endometriosis, a non-lethal cancer-like inflammatory condition, and cancer share common features, with the major being the inability of the organism to confront the cause of disease initiation due to an incompetent immune and homeostatic surveillance, respectively. In addition, and to a degree, both diseases can be detected by identical diagnostic tools and treatment can be successfully achieved by a number of common substances found in nature that can fortify the organism’s defense mechanisms to combat disease. Thus, this commentary focuses on and discusses the remedial action pine bark extracts (Pycnogenol®, almond skins, Agaricus Blazei murrill, oleuropein and oleocanthal may have on a destabilized organism that fails to combat illness by its own. Such a similarity in diagnosis and treatment may become as an alternative approach to create models of investigation for both diseases.

  2. Long-Term Homeostatic Properties Complementary to Hebbian Rules in CuPc-Based Multifunctional Memristor

    Science.gov (United States)

    Wang, Laiyuan; Wang, Zhiyong; Lin, Jinyi; Yang, Jie; Xie, Linghai; Yi, Mingdong; Li, Wen; Ling, Haifeng; Ou, Changjin; Huang, Wei

    2016-10-01

    Most simulations of neuroplasticity in memristors, which are potentially used to develop artificial synapses, are confined to the basic biological Hebbian rules. However, the simplex rules potentially can induce excessive excitation/inhibition, even collapse of neural activities, because they neglect the properties of long-term homeostasis involved in the frameworks of realistic neural networks. Here, we develop organic CuPc-based memristors of which excitatory and inhibitory conductivities can implement both Hebbian rules and homeostatic plasticity, complementary to Hebbian patterns and conductive to the long-term homeostasis. In another adaptive situation for homeostasis, in thicker samples, the overall excitement under periodic moderate stimuli tends to decrease and be recovered under intense inputs. Interestingly, the prototypes can be equipped with bio-inspired habituation and sensitization functions outperforming the conventional simplified algorithms. They mutually regulate each other to obtain the homeostasis. Therefore, we develop a novel versatile memristor with advanced synaptic homeostasis for comprehensive neural functions.

  3. Learning and retrieval behavior in recurrent neural networks with pre-synaptic dependent homeostatic plasticity

    Science.gov (United States)

    Mizusaki, Beatriz E. P.; Agnes, Everton J.; Erichsen, Rubem; Brunnet, Leonardo G.

    2017-08-01

    The plastic character of brain synapses is considered to be one of the foundations for the formation of memories. There are numerous kinds of such phenomenon currently described in the literature, but their role in the development of information pathways in neural networks with recurrent architectures is still not completely clear. In this paper we study the role of an activity-based process, called pre-synaptic dependent homeostatic scaling, in the organization of networks that yield precise-timed spiking patterns. It encodes spatio-temporal information in the synaptic weights as it associates a learned input with a specific response. We introduce a correlation measure to evaluate the precision of the spiking patterns and explore the effects of different inhibitory interactions and learning parameters. We find that large learning periods are important in order to improve the network learning capacity and discuss this ability in the presence of distinct inhibitory currents.

  4. Diversity and noise effects in a model of homeostatic regulation of the sleep-wake cycle.

    Directory of Open Access Journals (Sweden)

    Marco Patriarca

    Full Text Available Recent advances in sleep neurobiology have allowed development of physiologically based mathematical models of sleep regulation that account for the neuronal dynamics responsible for the regulation of sleep-wake cycles and allow detailed examination of the underlying mechanisms. Neuronal systems in general, and those involved in sleep regulation in particular, are noisy and heterogeneous by their nature. It has been shown in various systems that certain levels of noise and diversity can significantly improve signal encoding. However, these phenomena, especially the effects of diversity, are rarely considered in the models of sleep regulation. The present paper is focused on a neuron-based physiologically motivated model of sleep-wake cycles that proposes a novel mechanism of the homeostatic regulation of sleep based on the dynamics of a wake-promoting neuropeptide orexin. Here this model is generalized by the introduction of intrinsic diversity and noise in the orexin-producing neurons, in order to study the effect of their presence on the sleep-wake cycle. A simple quantitative measure of the quality of a sleep-wake cycle is introduced and used to systematically study the generalized model for different levels of noise and diversity. The model is shown to exhibit a clear diversity-induced resonance: that is, the best wake-sleep cycle turns out to correspond to an intermediate level of diversity at the synapses of the orexin-producing neurons. On the other hand, only a mild evidence of stochastic resonance is found, when the level of noise is varied. These results show that disorder, especially in the form of quenched diversity, can be a key-element for an efficient or optimal functioning of the homeostatic regulation of the sleep-wake cycle. Furthermore, this study provides an example of a constructive role of diversity in a neuronal system that can be extended beyond the system studied here.

  5. Corruption of homeostatic mechanisms in the guanylyl cyclase C signaling pathway underlying colorectal tumorigenesis

    Science.gov (United States)

    Waldman, Scott A

    2010-01-01

    Colon cancer, the second leading cause of cancer-related mortality worldwide, originates from the malignant transformation of intestinal epithelial cells. The intestinal epithelium undergoes a highly organized process of rapid regeneration along the crypt-villus axis, characterized by proliferation, migration, differentiation and apoptosis, whose coordination is essential to maintaining the mucosal barrier. Disruption of these homeostatic processes predisposes cells to mutations in tumor suppressors or oncogenes, whose dysfunction provides transformed cells an evolutionary growth advantage. While sequences of genetic mutations at different stages along the neoplastic continuum have been established, little is known of the events initiating tumorigenesis prior to adenomatous polyposis coli (APC) mutations. Here, we examine a role for the corruption of homeostasis induced by silencing novel tumor suppressors, including the intestine-specific transcription factor CDX2 and its gene target guanylyl cyclase C (GCC), as early events predisposing cells to mutations in APC and other sequential genes that initiate colorectal cancer. CDX2 and GCC maintain homeostatic regeneration in the intestine by restricting cell proliferation, promoting cell maturation and adhesion, regulating cell migration and defending the intestinal barrier and genomic integrity. Elimination of CDX2 or GCC promotes intestinal tumor initiation and growth in aged mice, mice carrying APC mutations or mice exposed to carcinogens. The roles of CDX2 and GCC in suppressing intestinal tumorigenesis, universal disruption in their signaling through silencing of hormones driving GCC, and the uniform overexpression of GCC by tumors underscore the potential value of oral replacement with GCC ligands as targeted prevention and therapy for colorectal cancer. PMID:20592492

  6. Reorganization of Sleep by Temperature in Drosophila Requires Light, the Homeostat, and the Circadian Clock.

    Science.gov (United States)

    Parisky, Katherine M; Agosto Rivera, José L; Donelson, Nathan C; Kotecha, Sejal; Griffith, Leslie C

    2016-04-04

    Increasing ambient temperature reorganizes the Drosophila sleep pattern in a way similar to the human response to heat, increasing daytime sleep while decreasing nighttime sleep. Mutation of core circadian genes blocks the immediate increase in daytime sleep, but not the heat-stimulated decrease in nighttime sleep, when animals are in a light:dark cycle. The ability of per(01) flies to increase daytime sleep in light:dark can be rescued by expression of PER in either LNv or DN1p clock cells and does not require rescue of locomotor rhythms. Prolonged heat exposure engages the homeostat to maintain daytime sleep in the face of nighttime sleep loss. In constant darkness, all genotypes show an immediate decrease in sleep in response to temperature shift during the subjective day, implying that the absence of light input uncovers a clock-independent pro-arousal effect of increased temperature. Interestingly, the effects of temperature on nighttime sleep are blunted in constant darkness and in cry(OUT) mutants in light:dark, suggesting that they are dependent on the presence of light the previous day. In contrast, flies of all genotypes kept in constant light sleep more at all times of day in response to high temperature, indicating that the presence of light can invert the normal nighttime response to increased temperature. The effect of temperature on sleep thus reflects coordinated regulation by light, the homeostat, and components of the clock, allowing animals to reorganize sleep patterns in response to high temperature with rough preservation of the total amount of sleep.

  7. Cross-modulation of homeostatic responses to temperature, oxygen and carbon dioxide in C. elegans.

    Directory of Open Access Journals (Sweden)

    Eiji Kodama-Namba

    Full Text Available Different interoceptive systems must be integrated to ensure that multiple homeostatic insults evoke appropriate behavioral and physiological responses. Little is known about how this is achieved. Using C. elegans, we dissect cross-modulation between systems that monitor temperature, O₂ and CO₂. CO₂ is less aversive to animals acclimated to 15°C than those grown at 22°C. This difference requires the AFD neurons, which respond to both temperature and CO₂ changes. CO₂ evokes distinct AFD Ca²⁺ responses in animals acclimated at 15°C or 22°C. Mutants defective in synaptic transmission can reprogram AFD CO₂ responses according to temperature experience, suggesting reprogramming occurs cell autonomously. AFD is exquisitely sensitive to CO₂. Surprisingly, gradients of 0.01% CO₂/second evoke very different Ca²⁺ responses from gradients of 0.04% CO₂/second. Ambient O₂ provides further contextual modulation of CO₂ avoidance. At 21% O₂ tonic signalling from the O₂-sensing neuron URX inhibits CO₂ avoidance. This inhibition can be graded according to O₂ levels. In a natural wild isolate, a switch from 21% to 19% O₂ is sufficient to convert CO₂ from a neutral to an aversive cue. This sharp tuning is conferred partly by the neuroglobin GLB-5. The modulatory effects of O₂ on CO₂ avoidance involve the RIA interneurons, which are post-synaptic to URX and exhibit CO₂-evoked Ca²⁺ responses. Ambient O₂ and acclimation temperature act combinatorially to modulate CO₂ responsiveness. Our work highlights the integrated architecture of homeostatic responses in C. elegans.

  8. 飞翼布局无人机反步L2增益纵向着陆鲁棒控制%Backstepping L2 gain robust control of longitudinal landing of flying-wing UAV

    Institute of Scientific and Technical Information of China (English)

    谭健; 周洲; 祝小平; 许晓平

    2016-01-01

    For the longitudinal landing control problem of flying⁃wing UAV with unknown external disturbances, a backstepping L2 gain robust control scheme based on super twisting sliding mode disturbance observer and tracking differentiator is proposed. The tracking differentiator is introduced to calculate the derivative of virtual control law which is very difficult to evaluate with the traditional backstepping control. Super twisting sliding mode disturbance observer and L2 gain robust item are designed to increase the robustness of the control system. Simulation results show:the altitude and airspeed of UAV are tracked on control command, vertical ground speed is within the allowable range. Compared with traditional PID control scheme, the proposed control scheme has better automatical landing control performance.%针对存在干扰的飞翼布局无人机纵向着陆控制问题,提出一种基于super twisting滑模干扰观测器与跟踪微分器的反步L2增益鲁棒控制方案。为解决反步控制虚拟控制量求导复杂的问题,设计了跟踪微分器对虚拟控制量进行求导,同时综合采用super twisting滑模干扰观测器和L2增益鲁棒项增强了控制系统的鲁棒性。仿真结果表明,无人机高度、空速都跟踪上控制指令,垂直接地速度在允许的范围内,与传统的PID着陆控制方案相比具有更好的着陆控制性能。

  9. Homeostasis 3: nurses as external agents of control in hypothyroidism.

    Science.gov (United States)

    Clancy, John; McVicar, Andrew

    The role of healthcare practitioners in reversing homeostatic imbalances essentially makes them external agents of homeostatic control-they are replacing the usual assessment, controlling and effector aspects that operate intrinsically in health (homeostasis) but have failed in ill-health (homeostatic imbalances). This article examines the homeostatic imbalance of hypothyroidism, using a case study to draw analogies between the components of homeostatic theory and those of the nursing process. After reading this article, nurses should be able to explain: how the components of homeostasis are associated with health, and how failure of one or more of these components of homeostasis is associated with illness; that illness arises from a cellular, and therefore chemical, homeostatic imbalance; that hypothyroidism is a cellular imbalance of low levels of thyroid hormone, which is identified by signs and symptoms (i.e. other homeostatic imbalances) related to these low levels; and understand how primary care nurses looking after people with hypothyroidism are acting as external agents of homeostatic control.

  10. Homeostasis 4: nurses as agents of control in myocardial infarction.

    Science.gov (United States)

    Clancy, John; McVicar, Andrew; Hubbard, Julia

    The role of health practitioners in attempting to reverse homeostatic imbalances essentially makes them external agents of homeostatic control-they are replacing the assessment, controlling and effector mechanisms that operate during health (homeostasis), but have failed in ill-health (homeostatic imbalances). Myocardial infarction (MI) is the homeostatic imbalance examined in this article, which aims to apply the analogy between the components of homeostatic theory and the components of the nursing process (Clancy and McVicar, 2011b) to the condition. After reading the article, nurses should be able to understand that: the components of homeostasis are associated with health, and the failure of one or more of these components results in illness; illness arises from a cellular, hence chemical, homeostatic imbalance(s); MI results from a cellular imbalance leading to a restriction in blood flow to the myocardium, and is identified by signs and symptoms (i.e. other homeostatic imbalances) related to the ischaemia; when caring for people with MI, coronary care nurses are acting as external agents of homeostatic control.

  11. Giant enhancement of optical high-order sideband generation and their control in a dimer of two cavities with gain and loss

    Science.gov (United States)

    Li, Jiahui; Li, Jiahua; Xiao, Qian; Wu, Ying

    2016-06-01

    Parity-time (PT ) symmetric systems, which rely on the balanced gain-loss condition and render the Hamiltonian non-Hermitian, have provided a new platform to engineer effective light-matter interactions in recent years. Here we explore the high-order sideband features of the output fields obtained from a PT -symmetric optical system consisting of a passive nonlinear cavity coupled to an active linear cavity. By employing a perturbation technique, we derive analytic formulas used to determine the nonlinear transmission coefficient of optical second-order sideband in this structure. Using experimentally achievable parameters, it is clearly shown that the efficiency of the second-order sideband generation can be greatly enhanced in the PT -symmetric dimer, extremely in the vicinity of the transition point from unbroken- to broken-PT regimes. Moreover, we further analyzed the influences of the system parameters, including the photon-tunneling rate between two cavities, Kerr nonlinearity strength, and optical detuning, on the second-order sideband generation. Subsequently we investigate the higher-order sideband output spectrum by numerical simulations, where the sideband amplitude also is largely enhanced in the PT -symmetric arrangement, compared with the passive-passive double-cavity system. Our obtained results provide a new avenue for acquiring optical high-order sidebands and operating light, which may inspire further applications in chip-scale optical communications and optical frequency combs.

  12. Ability to Gain Control Over One’s Own Brain Activity and its Relation to Spiritual Practice: A Multimodal Imaging Study

    Directory of Open Access Journals (Sweden)

    Silvia E. Kober

    2017-05-01

    Full Text Available Spiritual practice, such as prayer or meditation, is associated with focusing attention on internal states and self-awareness processes. As these cognitive control mechanisms presumably are also important for neurofeedback (NF, we investigated whether people who pray frequently (N = 20 show a higher ability of self-control over their own brain activity compared to a control group of individuals who rarely pray (N = 20. All participants underwent structural magnetic resonance imaging (MRI and one session of sensorimotor rhythm (SMR, 12–15 Hz based NF training. Individuals who reported a high frequency of prayer showed improved NF performance compared to individuals who reported a low frequency of prayer. The individual ability to control one’s own brain activity was related to volumetric aspects of the brain. In the low frequency of prayer group, gray matter volumes in the right insula and inferior frontal gyrus were positively associated with NF performance, supporting prior findings that more general self-control networks are involved in successful NF learning. In contrast, participants who prayed regularly showed a negative association between gray matter volume in the left medial orbitofrontal cortex (Brodmann’s area (BA 10 and NF performance. Due to their regular spiritual practice, they might have been more skillful in gating incoming information provided by the NF system and avoiding task-irrelevant thoughts.

  13. Ghrelin modulates the fMRI BOLD response of homeostatic and hedonic brain centers regulating energy balance in the rat.

    Directory of Open Access Journals (Sweden)

    Miklós Sárvári

    Full Text Available The orexigenic gut-brain peptide, ghrelin and its G-protein coupled receptor, the growth hormone secretagogue receptor 1a (GHS-R1A are pivotal regulators of hypothalamic feeding centers and reward processing neuronal circuits of the brain. These systems operate in a cooperative manner and receive a wide array of neuronal hormone/transmitter messages and metabolic signals. Functional magnetic resonance imaging was employed in the current study to map BOLD responses to ghrelin in different brain regions with special reference on homeostatic and hedonic regulatory centers of energy balance. Experimental groups involved male, ovariectomized female and ovariectomized estradiol-replaced rats. Putative modulation of ghrelin signaling by endocannabinoids was also studied. Ghrelin-evoked effects were calculated as mean of the BOLD responses 30 minutes after administration. In the male rat, ghrelin evoked a slowly decreasing BOLD response in all studied regions of interest (ROI within the limbic system. This effect was antagonized by pretreatment with GHS-R1A antagonist JMV2959. The comparison of ghrelin effects in the presence or absence of JMV2959 in individual ROIs revealed significant changes in the prefrontal cortex, nucleus accumbens of the telencephalon, and also within hypothalamic centers like the lateral hypothalamus, ventromedial nucleus, paraventricular nucleus and suprachiasmatic nucleus. In the female rat, the ghrelin effects were almost identical to those observed in males. Ovariectomy and chronic estradiol replacement had no effect on the BOLD response. Inhibition of the endocannabinoid signaling by rimonabant significantly attenuated the response of the nucleus accumbens and septum. In summary, ghrelin can modulate hypothalamic and mesolimbic structures controlling energy balance in both sexes. The endocannabinoid signaling system contributes to the manifestation of ghrelin's BOLD effect in a region specific manner. In females, the

  14. Homeostatic imbalance and colon cancer: the dynamic epigenetic interplay of inflammation, environmental toxins, and chemopreventive plant compounds.

    Science.gov (United States)

    Sokolosky, Melissa L; Wargovich, Michael J

    2012-01-01

    The advent of modern medicine has allowed for significant advances within the fields of emergency care, surgery, and infectious disease control. Health threats that were historically responsible for immeasurable tolls on human life are now all but eradicated within certain populations, specifically those that enjoy higher degrees of socio-economic status and access to healthcare. However, modernization and its resulting lifestyle trends have ushered in a new era of chronic illness; one in which an unprecedented number of people are estimated to contract cancer and other inflammatory diseases. Here, we explore the idea that homeostasis has been redefined within just a few generations, and that diseases such as colorectal cancer are the result of fluctuating physiological and molecular imbalances. Phytochemical-deprived, pro-inflammatory diets combined with low-dose exposures to environmental toxins, including bisphenol-A (BPA) and other endocrine disruptors, are now linked to increasing incidences of cancer in westernized societies and developing countries. There is recent evidence that disease determinants are likely set in utero and further perpetuated into adulthood dependent upon the innate and environmentally acquired phenotype unique to each individual. In order to address a disease as multi-factorial, case-specific, and remarkably adaptive as cancer, research must focus on its root causes in order to elucidate the molecular mechanisms by which they can be prevented or counteracted via plant-derived compounds such as epigallocatechin-3-gallate (EGCG) and resveratrol. The significant role of epigenetics in the regulation of these complex processes is emphasized here to form a comprehensive view of the dynamic interactions that influence modern-day carcinogenesis, and how sensibly restoring homeostatic balance may be the key to the cancer riddle.

  15. Homeostatic imbalance and colon cancer: the dynamic epigenetic interplay of inflammation, environmental toxins, and chemopreventive plant compounds

    Directory of Open Access Journals (Sweden)

    Melissa L Sokolosky

    2012-06-01

    Full Text Available The advent of modern medicine has allowed for significant advances within the fields of emergency care, surgery, and infectious disease control. Health threats that were historically responsible for immeasurable tolls on human life are now all but eradicated within certain populations, specifically those that enjoy higher degrees of socio-economic status and access to healthcare. However, modernization and its resulting lifestyle trends have ushered in a new era of chronic illness; one in which an unprecedented number of people are estimated to contract cancer and other inflammatory diseases. Here, we explore the idea that homeostasis has been redefined within just a few generations, and that diseases such as colorectal cancer are the result of fluctuating physiological and molecular imbalances. Phytochemical-deprived, pro-inflammatory diets combined with low-dose exposures to environmental toxins, including bisphenol-A (BPA and other endocrine disruptors, are now linked to increasing incidences of cancer in westernized societies and developing countries. There is recent evidence that disease determinants are likely set in utero and further perpetuated into adulthood dependent upon the innate and environmentally-acquired genetic profile unique to each individual. In order to address a disease as multi-factorial, case-specific, and remarkably adaptive as cancer, research must focus on its root causes in order to elucidate the molecular mechanisms by which they can be prevented or counteracted via plant-derived compounds like epigallocatechin-3-gallate (EGCG and resveratrol. The significant role of epigenetics in the regulation of these complex processes is emphasized here to form a comprehensive view of the dynamic interactions that influence modern-day carcinogenesis, and how restoring homeostatic balance may be the key to the cancer riddle.

  16. Homeostasis 6: nurses as external control agents in rheumatoid arthritis.

    Science.gov (United States)

    Clancy, John; McVicar, Andrew; Mooney, Janice

    All disorders involve a disturbance of cellular and hence chemical function in the body. Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory disease that usually attacks synovial joints and surrounding ligaments, muscles and their tendons and blood vessels. This article applies the concept of health professionals operating as external agents of homeostatic control (Clancy and McVicar, 20011a; 2011b) to RA and to the care of affected patients, using a case scenario to illustrate attempts to minimize homeostatic imbalances. After reading the article, nurses should be able to understand: how the principles of homeostatic theory apply to skeletomuscular function, in particular to synovial joint function; the skeletomuscular homeostatic role in movement; and that homeostatic failure of reduced mobility, as in RA, is a result of nature-nurture interaction; that illness arises from a cellular, hence chemical, homeostatic imbalance(s) (Clancy and McVicar, 2011a; 2011b; 2011c; 2011d; 2011e). RA is considered a cellular (B-lymphocyte) hence chemical (autoantibody) imbalance that causes the homeostatic imbalances (inflammatory pain, reduced mobility, reduced activities of daily living) associated with the condition. Health professionals are able at act as external agents of homeostatic control to only a limited extent when caring for people with RA because, as with any progressive disorder, they will only be managing signs and symptoms to improve patients' quality of life.

  17. A single-cross, RNA interference-based genetic tool for examining the long-term maintenance of homeostatic plasticity

    Directory of Open Access Journals (Sweden)

    Douglas J. Brusich

    2015-03-01

    Full Text Available Homeostatic synaptic plasticity (HSP helps neurons and synapses maintain physiologically appropriate levels of output. The fruit fly Drosophila melanogaster larval neuromuscular junction (NMJ is a valuable model for studying HSP. Here we introduce a genetic tool that allows fruit fly researchers to examine the lifelong maintenance of HSP with a single cross. The tool is a fruit fly stock that combines the GAL4/UAS expression system with RNA interference (RNAi-based knock down of a glutamate receptor subunit gene. With this stock, we uncover important new information about the maintenance of HSP. We address an open question about the role that presynaptic CaV2-type Ca2+ channels play in NMJ homeostasis. Published experiments have demonstrated that hypomorphic missense mutations in the CaV2 α1a subunit gene cacophony (cac can impair homeostatic plasticity at the NMJ. Here we report that reducing cac expression levels by RNAi is not sufficient to impair homeostatic plasticity. The presence of wild-type channels appears to support HSP – even when total CaV2 function is severely reduced. We also conduct an RNAi- and electrophysiology-based screen to identify new factors required for sustained homeostatic signaling throughout development. We uncover novel roles in HSP for Drosophila homologs of Cysteine string protein (CSP and Phospholipase Cβ (Plc21C. We characterize those roles through follow-up genetic tests. We discuss how CSP, Plc21C, and associated factors could modulate presynaptic CaV2 function, presynaptic Ca2+ handling, or other signaling processes crucial for sustained homeostatic regulation of NMJ function throughout development. Our findings expand the scope of signaling pathways and processes that contribute to the durable strength of the NMJ.

  18. A single-cross, RNA interference-based genetic tool for examining the long-term maintenance of homeostatic plasticity.

    Science.gov (United States)

    Brusich, Douglas J; Spring, Ashlyn M; Frank, C Andrew

    2015-01-01

    Homeostatic synaptic plasticity (HSP) helps neurons and synapses maintain physiologically appropriate levels of output. The fruit fly Drosophila melanogaster larval neuromuscular junction (NMJ) is a valuable model for studying HSP. Here we introduce a genetic tool that allows fruit fly researchers to examine the lifelong maintenance of HSP with a single cross. The tool is a fruit fly stock that combines the GAL4/UAS expression system with RNA interference (RNAi)-based knock down of a glutamate receptor subunit gene. With this stock, we uncover important new information about the maintenance of HSP. We address an open question about the role that presynaptic CaV2-type Ca(2+) channels play in NMJ homeostasis. Published experiments have demonstrated that hypomorphic missense mutations in the CaV2 α1a subunit gene cacophony (cac) can impair homeostatic plasticity at the NMJ. Here we report that reducing cac expression levels by RNAi is not sufficient to impair homeostatic plasticity. The presence of wild-type channels appears to support HSP-even when total CaV2 function is severely reduced. We also conduct an RNAi- and electrophysiology-based screen to identify new factors required for sustained homeostatic signaling throughout development. We uncover novel roles in HSP for Drosophila homologs of Cysteine string protein (CSP) and Phospholipase Cβ (Plc21C). We characterize those roles through follow-up genetic tests. We discuss how CSP, Plc21C, and associated factors could modulate presynaptic CaV2 function, presynaptic Ca(2+) handling, or other signaling processes crucial for sustained homeostatic regulation of NMJ function throughout development. Our findings expand the scope of signaling pathways and processes that contribute to the durable strength of the NMJ.

  19. Change, Gain and Loss

    Institute of Scientific and Technical Information of China (English)

    Fu Mengzi

    2006-01-01

    @@ Five years have passed since the September 11 terrorist attacks occurred. America's counter-terrorism campaign is still on the way.Besides the momentary monumental significance of the fifth anniversary, five years is still too short in regard to the long-term counter-terrorism campaign. Yet, America's president's tenure is eight years at best; most of Bush's presidency time has passed. Five years ago, the U. S. encountered the most serious terrorist attack; the whole nation formed a consensus that counter-terrorism is its utmost priority. President Bush once enjoyed a support rate as high as 90% for over 16 months. But five years later, the trend changes. People can not help but ask: what are the gains and losses of the Republican Party in dealing with national security affairs?

  20. 高频增益符号未知时的变结构模型参考自适应控制%Variable Structure Model Reference Adaptive Control with Unknown High Frequency Gain Sign

    Institute of Scientific and Technical Information of China (English)

    董文瀚; 孙秀霞; 林岩

    2007-01-01

    A variable structure model reference adaptive control for plants with relative degree greater than one and unknown high frequency gain sign is proposed. A switching scheme is introduced based on a monitoring function designed for the first auxiliary error of the close loop system. It is shown that under the supervision of the monitoring function, the switching stops after at most a finite number of switchings and the tracking error converges to a residual set that can be made arbitrarily small by appropriately choosing some design parameters.

  1. Gain Efficient L-band EDFA With Dynamic Gain Equalization

    Institute of Scientific and Technical Information of China (English)

    Xiaoli Hui; Rujian Lin

    2003-01-01

    A gain efficient L-band erbium-doped fiber amplifier with dynamic gain equalization is presented. Using a single fiber Bragg grating and a static equalizer, the gain is clamped at 27dB with less than 0.5dB variations over 35nm.

  2. PER3 polymorphism predicts cumulative sleep homeostatic but not neurobehavioral changes to chronic partial sleep deprivation.

    Directory of Open Access Journals (Sweden)

    Namni Goel

    Full Text Available BACKGROUND: The variable number tandem repeat (VNTR polymorphism 5-repeat allele of the circadian gene PERIOD3 (PER3(5/5 has been associated with cognitive decline at a specific circadian phase in response to a night of total sleep deprivation (TSD, relative to the 4-repeat allele (PER3(4/4. PER3(5/5 has also been related to higher sleep homeostasis, which is thought to underlie this cognitive vulnerability. To date, no study has used a candidate gene approach to investigate the response to chronic partial sleep deprivation (PSD, a condition distinct from TSD and one commonly experienced by millions of people on a daily and persistent basis. We evaluated whether the PER3 VNTR polymorphism contributed to cumulative neurobehavioral deficits and sleep homeostatic responses during PSD. METHODOLOGY/PRINCIPAL FINDINGS: PER3(5/5 (n = 14, PER3(4/5 (n = 63 and PER3(4/4 (n = 52 healthy adults (aged 22-45 y demonstrated large, but equivalent cumulative decreases in cognitive performance and physiological alertness, and cumulative increases in sleepiness across 5 nights of sleep restricted to 4 h per night. Such effects were accompanied by increasing daily inter-subject variability in all groups. The PER3 genotypes did not differ significantly at baseline in habitual sleep, physiological sleep structure, circadian phase, physiological sleepiness, cognitive performance, or subjective sleepiness, although during PSD, PER3(5/5 subjects had slightly but reliably elevated sleep homeostatic pressure as measured physiologically by EEG slow-wave energy in non-rapid eye movement sleep compared with PER3(4/4 subjects. PER3 genotypic and allelic frequencies did not differ significantly between Caucasians and African Americans. CONCLUSIONS/SIGNIFICANCE: The PER3 VNTR polymorphism was not associated with individual differences in neurobehavioral responses to PSD, although it was related to one marker of sleep homoeostatic response during PSD. The comparability of PER3

  3. Intrinsic gain modulation and adaptive neural coding.

    Directory of Open Access Journals (Sweden)

    Sungho Hong

    Full Text Available In many cases, the computation of a neural system can be reduced to a receptive field, or a set of linear filters, and a thresholding function, or gain curve, which determines the firing probability; this is known as a linear/nonlinear model. In some forms of sensory adaptation, these linear filters and gain curve adjust very rapidly to changes in the variance of a randomly varying driving input. An apparently similar but previously unrelated issue is the observation of gain control by background noise in cortical neurons: the slope of the firing rate versus current (f-I curve changes with the variance of background random input. Here, we show a direct correspondence between these two observations by relating variance-dependent changes in the gain of f-I curves to characteristics of the changing empirical linear/nonlinear model obtained by sampling. In the case that the underlying system is fixed, we derive relationships relating the change of the gain with respect to both mean and variance with the receptive fields derived from reverse correlation on a white noise stimulus. Using two conductance-based model neurons that display distinct gain modulation properties through a simple change in parameters, we show that coding properties of both these models quantitatively satisfy the predicted relationships. Our results describe how both variance-dependent gain modulation and adaptive neural computation result from intrinsic nonlinearity.

  4. A randomized controlled trial comparing the efficacy and safety of two HMG preparations gaining their LH bioactivity from different HCG sources

    DEFF Research Database (Denmark)

    Lockwood, Gillian; Cometti, Barbara; Bogstad, Jeanette

    2017-01-01

    In this prospective, controlled, randomized, multicentre, non-inferiority study, efficacy and safety of two HMG preparations (Menopur(®)- Ferring and Meriofert®- IBSA Institut Biochimique SA) for ovarian stimulation were compared (270 women undergoing IVF aged between 18 and 39 years; BMI 30 kg/m(2......) or less; less than three prior completed assisted reproduction technique cycles). A standard long down-regulation with gonadotrophin-releasing hormone agonist protocol, with HCG triggering was used; primary end-point was total number of oocytes retrieved; attention was paid toovarian hyperstimulation...... syndrome (OHSS). No statistically significant differences between the treatment groups were reported for most of the clinically significant end-points, including embryo quality, fertilization rate, implantation rate, ongoing pregnancy rate and live birth rate. Total number of oocytes retrieved was higher...

  5. Good maintenance of exercise-induced bone gain with decreased training of female tennis and squash players: a prospective 5-year follow-up study of young and old starters and controls.

    Science.gov (United States)

    Kontulainen, S; Kannus, P; Haapasalo, H; Sievänen, H; Pasanen, M; Heinonen, A; Oja, P; Vuori, I

    2001-02-01

    This prospective 5-year follow-up study of 64 adult female racquet sports players and 27 controls assessed the changes in the playing-to-nonplaying arm bone mineral content (BMC) differences to answer three questions: (1) Are training-induced bone gains lost with decreased training? (2) Is the bone response to decreased training different if the playing career has been started before or at puberty rather than after it? (3) Are the possible bone changes related to the changes in training? The players were divided into two groups according to the starting age of their tennis or squash playing. The mean starting age was 10.5 years (SD, 2.2) among the players who had started training before or at menarche (young starters; n = 36) while 26.4 years (SD, 8.0) among those players who had begun training a minimum of 1 year after menarche (old starters; n = 28). At baseline of the 5-year follow-up, the mean age of the young starters was 21.6 years (SD, 7.6) and that of old starters was 39.4 years (SD, 10.5). During the follow-up, the young starters had reduced the average training frequency from 4.7 times a week (2.7) to 1.4 times a week (1.3) and the old starters from 4.0 times a week (1.4) to 2.0 times a week (1.4), respectively. The 5-year follow-up revealed that despite reduced training the exercise-induced bone gain was well maintained in both groups of players regardless of their clearly different starting age of activity and different amount of exercise-induced bone gain. The gain was still 1.3-2.2 times greater in favor of the young starters (at the follow-up, the dominant-to-nondominant arm BMC difference was 22% [8.4] in the humeral shaft of the young starters versus 10% [3.8] in the old starters, and 3.5% [2.4] in controls). In the players, changes in training were only weakly related to changes in the side-to-side BMC difference (r(s) = 0.05-0.34, all NS), and this was true even among the players who had stopped training completely a minimum 1 year before the

  6. Leading Gainful Employment Metric Reporting

    Science.gov (United States)

    Powers, Kristina; MacPherson, Derek

    2016-01-01

    This chapter will address the importance of intercampus involvement in reporting of gainful employment student-level data that will be used in the calculation of gainful employment metrics by the U.S. Department of Education. The authors will discuss why building relationships within the institution is critical for effective gainful employment…

  7. Process evaluation of TXT2BFiT: a multi-component mHealth randomised controlled trial to prevent weight gain in young adults.

    Science.gov (United States)

    Partridge, Stephanie R; Allman-Farinelli, Margaret; McGeechan, Kevin; Balestracci, Kate; Wong, Annette T Y; Hebden, Lana; Harris, Mark F; Bauman, Adrian; Phongsavan, Philayrath

    2016-01-19

    TXT2BFiT was one of the first few innovative mHealth programs designed for young adults (18-35 years) with demonstrated efficacy in weight management. However, research is lacking to understand intervention effectiveness, especially in complex, multi-component mHealth programs. This paper investigates participant perceptions of and engagement with the mHealth program components in the TXT2BFiT to understand program effects. Process evaluation data were collected continuously for the study duration. The TXT2BFiT program was a multi-component lifestyle program delivered intensively for 3-month followed by a 6-month maintenance phase. Program components included personalised coaching calls, text messages, emails, smartphone apps and website access. Process evaluation measures included frequency of use of components and frequency for number of components used (online survey data); dose delivered and engagement with program components (researcher logs and web platform reports); frequency, timing and difficulties experienced with program components (online survey data) and overall perceptions of program components (online survey data and semi-structured telephone interviews). Qualitative data analysis was performed using NVivo10. Over 80% of participants completed post-intervention (3-months, intervention, n = 110, control n = 104) and follow-up surveys (9-months, intervention, n = 96, control n = 104). Thirty intervention participants completed semi-structured telephone interviews. Participants reported high use of coaching calls, text messages and emails and no issues in content delivery from these components. These components were described as helping them to achieve their goals. Website and app use and engagement was low for the duration of the program. Participants would prefer incorporation of the self-monitoring apps and website resources into one smartphone application that can be individualised by entry of their personal data. Our process

  8. Homeostatic properties and phenotypic maturation of murine CD4+ pre-thymic emigrants in the thymus.

    Directory of Open Access Journals (Sweden)

    Jie Dong

    Full Text Available After a tightly regulated developmental program in the thymus, "mature" single positive (SP thymocytes leave the thymus and enter the periphery. These newly arrived recent thymic emigrants (RTEs are phenotypically and functionally immature, and will complete a dynamic maturation in the peripheral lymphoid organs before being licensed to be resident naïve T cells. To study the early events occurring in the RTE maturation process, we identified the phenotype of CD4(+ pre-RTEs, a population of CD4(+ SP thymocytes that have acquired the thymus egress capability. Compared to peripheral naïve T cells, CD4(+ pre-RTEs displayed superior survival capability in lymphoreplete mice and faster proliferation under lymphopenic condition. The differences in Bcl2/Bim expression and/or heightened IL-7 signaling pathway may account for the pre-RTEs' better responsiveness to homeostatic signals. Qa2, the expression of which indicates the phenotypic maturation of SPs and RTEs, was found to be upregulated in CD4(+ pre-RTEs in thymic perivascular space. Migratory dendritic cells that surround this region contribute to Qa2 expression in pre-RTEs. The dendritic cell-driven Qa2 induction of CD4(+ pre-RTEs is independent of MHC class II and Aire molecules.

  9. An intestinal microRNA modulates the homeostatic adaptation to chronic oxidative stress in C. elegans

    Science.gov (United States)

    Kato, Masaomi; Kashem, Mohammed Abul; Cheng, Chao

    2016-01-01

    Adaptation to an environmental or metabolic perturbation is a feature of the evolutionary process. Recent insights into microRNA function suggest that microRNAs serve as key players in a robust adaptive response against stress in animals through their capacity to fine-tune gene expression. However, it remains largely unclear how a microRNA-modulated downstream mechanism contributes to the process of homeostatic adaptation. Here we show that loss of an intestinally expressed microRNA gene, mir-60, in the nematode C. elegans promotes an adaptive response to chronic – a mild and long-term – oxidative stress exposure. The pathway involved appears to be unique since the canonical stress-responsive factors, such as DAF-16/FOXO, are dispensable for mir-60 loss to enhance oxidative stress resistance. Gene expression profiles revealed that genes encoding lysosomal proteases and those involved in xenobiotic metabolism and pathogen defense responses are up-regulated by the loss of mir-60. Detailed genetic studies and computational microRNA target prediction suggest that endocytosis components and a bZip transcription factor gene zip-10, which functions in innate immune response, are directly modulated by miR-60 in the intestine. Our findings suggest that the mir-60 loss facilitates adaptive response against chronic oxidative stress by ensuring the maintenance of cellular homeostasis. PMID:27623524

  10. EEG delta oscillations as a correlate of basic homeostatic and motivational processes.

    Science.gov (United States)

    Knyazev, Gennady G

    2012-01-01

    Functional significance of delta oscillations is not fully understood. One way to approach this question would be from an evolutionary perspective. Delta oscillations dominate the EEG of waking reptiles. In humans, they are prominent only in early developmental stages and during slow-wave sleep. Increase of delta power has been documented in a wide array of developmental disorders and pathological conditions. Considerable evidence on the association between delta waves and autonomic and metabolic processes hints that they may be involved in integration of cerebral activity with homeostatic processes. Much evidence suggests the involvement of delta oscillations in motivation. They increase during hunger, sexual arousal, and in substance users. They also increase during panic attacks and sustained pain. In cognitive domain, they are implicated in attention, salience detection, and subliminal perception. This evidence shows that delta oscillations are associated with evolutionary old basic processes, which in waking adults are overshadowed by more advanced processes associated with higher frequency oscillations. The former processes rise in activity, however, when the latter are dysfunctional.

  11. Renegade homeostatic cytokine responses in T1D: drivers of regulatory/effector T cell imbalance.

    Science.gov (United States)

    Gupta, Shipra; Cerosaletti, Karen; Long, S Alice

    2014-04-01

    Homeostatic cytokines contribute to the balance between regulatory and effector T cells (Tregs and Teffs respectively) and are necessary to maintain peripheral tolerance. These cytokines include IL-2 that supports Treg and IL-7 and IL-15 that drive Teff. In overt settings of lost tolerance (i.e. graft rejection), IL-2 Treg signatures are decreased while IL-7 and IL-15 Teff signatures are often enhanced. Similar cytokine profile imbalances also occur in some autoimmune diseases. In type 1 diabetes (T1D), there are underlying defects in the IL-2 pathway and Teff cytokine blockade can prevent and treat diabetes in NOD mice. In this review, we summarize evidence of IL-2, IL-7 and IL-15 genetic and cellular alterations in T1D patients. We then discuss how the combined effect of these cytokine profiles may together contribute to altered Treg/Teff ratios and functions in T1D. Implications for combination therapies and suggestions for integrated cytokine and Treg/Teff biomarker development are then proposed. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Homeostatic migration and distribution of innate immune cells in primary and secondary lymphoid organs with ageing.

    Science.gov (United States)

    Nikolich-Žugich, J; Davies, J S

    2017-03-01

    Ageing of the innate and adaptive immune system, collectively termed immune senescence, is a complex process. One method to understand the components of ageing involves dissociating the effects of ageing on the cells of the immune system, on the microenvironment in lymphoid organs and tissues where immune cells reside and on the circulating factors that interact with both immune cells and their microenvironment. Heterochronic parabiosis, a surgical union of two organisms of disparate ages, is ideal for this type of study, as it has the power to dissociate the age of the cell and the age of the microenvironment into which the cell resides or is migrating. So far, however, it has been used sparingly to study immune ageing. Here we review the limited literature on homeostatic innate immune cell trafficking in ageing in the absence of chronic inflammation. We also review our own recent data on trafficking of innate immune subsets between primary and secondary lymphoid organs in heterochronic parabiosis. We found no systemic bias in retention or acceptance of neutrophils, macrophages, dendritic cells or natural killer cells with ageing in primary and secondary lymphoid organs. We conclude that these four innate immune cell types migrate to and populate lymphoid organs (peripheral lymph nodes, spleen and bone marrow), regardless of their own age and of the age of lymphoid organs. © 2017 British Society for Immunology.

  13. Emerging Link between Alzheimer’s Disease and Homeostatic Synaptic Plasticity

    Directory of Open Access Journals (Sweden)

    Sung-Soo Jang

    2016-01-01

    Full Text Available Alzheimer’s disease (AD is an irreversible brain disorder characterized by progressive cognitive decline and neurodegeneration of brain regions that are crucial for learning and memory. Although intracellular neurofibrillary tangles and extracellular senile plaques, composed of insoluble amyloid-β (Aβ peptides, have been the hallmarks of postmortem AD brains, memory impairment in early AD correlates better with pathological accumulation of soluble Aβ oligomers and persistent weakening of excitatory synaptic strength, which is demonstrated by inhibition of long-term potentiation, enhancement of long-term depression, and loss of synapses. However, current, approved interventions aiming to reduce Aβ levels have failed to retard disease progression; this has led to a pressing need to identify and target alternative pathogenic mechanisms of AD. Recently, it has been suggested that the disruption of Hebbian synaptic plasticity in AD is due to aberrant metaplasticity, which is a form of homeostatic plasticity that tunes the magnitude and direction of future synaptic plasticity based on previous neuronal or synaptic activity. This review examines emerging evidence for aberrant metaplasticity in AD. Putative mechanisms underlying aberrant metaplasticity in AD will also be discussed. We hope this review inspires future studies to test the extent to which these mechanisms contribute to the etiology of AD and offer therapeutic targets.

  14. Retinoic acid receptor regulation of epimorphic and homeostatic regeneration in the axolotl.

    Science.gov (United States)

    Nguyen, Matthew; Singhal, Pankhuri; Piet, Judith W; Shefelbine, Sandra J; Maden, Malcolm; Voss, S Randal; Monaghan, James R

    2017-02-15

    Salamanders are capable of regenerating amputated limbs by generating a mass of lineage-restricted cells called a blastema. Blastemas only generate structures distal to their origin unless treated with retinoic acid (RA), which results in proximodistal (PD) limb duplications. Little is known about the transcriptional network that regulates PD duplication. In this study, we target specific retinoic acid receptors (RARs) to either PD duplicate (RA treatment or RARγ agonist) or truncate (RARβ antagonist) regenerating limbs. RARE-EGFP reporter axolotls showed divergent reporter activity in limbs undergoing PD duplication versus truncation, suggesting differences in patterning and skeletal regeneration. Transcriptomics identified expression patterns that explain PD duplication, including upregulation of proximal homeobox gene expression and silencing of distal-associated genes, whereas limb truncation was associated with disrupted skeletal differentiation. RARβ antagonism in uninjured limbs induced a loss of skeletal integrity leading to long bone regression and loss of skeletal turnover. Overall, mechanisms were identified that regulate the multifaceted roles of RARs in the salamander limb including regulation of skeletal patterning during epimorphic regeneration, skeletal tissue differentiation during regeneration, and homeostatic regeneration of intact limbs.

  15. Age-related regulation of genes: slow homeostatic changes and age-dimension technology

    Science.gov (United States)

    Kurachi, Kotoku; Zhang, Kezhong; Huo, Jeffrey; Ameri, Afshin; Kuwahara, Mitsuhiro; Fontaine, Jean-Marc; Yamamoto, Kei; Kurachi, Sumiko

    2002-11-01

    Through systematic studies of pro- and anti-blood coagulation factors, we have determined molecular mechanisms involving two genetic elements, age-related stability element (ASE), GAGGAAG and age-related increase element (AIE), a unique stretch of dinucleotide repeats (AIE). ASE and AIE are essential for age-related patterns of stable and increased gene expression patterns, respectively. Such age-related gene regulatory mechanisms are also critical for explaining homeostasis in various physiological reactions as well as slow homeostatic changes in them. The age-related increase expression of the human factor IX (hFIX) gene requires the presence of both ASE and AIE, which apparently function additively. The anti-coagulant factor protein C (hPC) gene uses an ASE (CAGGAG) to produce age-related stable expression. Both ASE sequences (G/CAGAAG) share consensus sequence of the transcriptional factor PEA-3 element. No other similar sequences, including another PEA-3 consensus sequence, GAGGATG, function in conferring age-related gene regulation. The age-regulatory mechanisms involving ASE and AIE apparently function universally with different genes and across different animal species. These findings have led us to develop a new field of research and applications, which we named “age-dimension technology (ADT)”. ADT has exciting potential for modifying age-related expression of genes as well as associated physiological processes, and developing novel, more effective prophylaxis or treatments for age-related diseases.

  16. Homeostatic model assessment and risk for hypertension during pregnancy: a longitudinal prospective study.

    Science.gov (United States)

    Romero-Gutiérrez, Gustavo; Malacara, Juan Manuel; Amador, Norma; Fierro-Martínez, César; Muñoz-Guevara, Luis Manuel; Molina-Rodríguez, Roberto

    2004-11-01

    The purpose of this study was to determine the association between insulin resistance and hypertension during pregnancy with the homeostatic model assessment (HOMA-IR). A longitudinal prospective study was carried out. One hundred sixty normotensive pregnant women were followed from the first trimester until delivery. HOMA-IR levels were determined each trimester. Statistical analysis included one-way analysis of variance and multivariate logistic regression. At follow-up, 134 women (83.8%) remained normotensive, 18 (11.2%) developed gestational hypertension, and 8 (5%) developed preeclampsia. At first trimester, HOMA-IR levels were higher in women who developed gestational hypertension (2.1 +/- 0.2) than in women who developed preeclampsia (1.2 +/- 0.0), or remained normotensive (1.2 +/- 0.3); p < 0.01. In the logistic regression analysis, HOMA-IR levels at first trimester were statistically significant ( p = 0.03) to predict development of gestational hypertension. Our results support the use of the HOMA-IR as an alternative index for the assessment of the risk for hypertension during pregnancy.

  17. Effects of homeostatic constraints on associative memory storage and synaptic connectivity of cortical circuits

    Directory of Open Access Journals (Sweden)

    Julio eChapeton

    2015-06-01

    Full Text Available The impact of learning and long-term memory storage on synaptic connectivity is not completely understood. In this study, we examine the effects of associative learning on synaptic connectivity in adult cortical circuits by hypothesizing that these circuits function in a steady-state, in which the memory capacity of a circuit is maximal and learning must be accompanied by forgetting. Steady-state circuits should be characterized by unique connectivity features. To uncover such features we developed a biologically constrained, exactly solvable model of associative memory storage. The model is applicable to networks of multiple excitatory and inhibitory neuron classes and can account for homeostatic constraints on the number and the overall weight of functional connections received by each neuron. The results show that in spite of a large number of neuron classes, functional connections between potentially connected cells are realized with less than 50% probability if the presynaptic cell is excitatory and generally a much greater probability if it is inhibitory. We also find that constraining the overall weight of presynaptic connections leads to Gaussian connection weight distributions that are truncated at zero. In contrast, constraining the total number of functional presynaptic connections leads to non-Gaussian distributions, in which weak connections are absent. These theoretical predictions are compared with a large dataset of published experimental studies reporting amplitudes of unitary postsynaptic potentials and probabilities of connections between various classes of excitatory and inhibitory neurons in the cerebellum, neocortex, and hippocampus.

  18. PMSG风力发电系统的最优跟踪增益调度控制%Optimal Tracking Gain Scheduling Control for PMSG-Based Wind Power Generation System

    Institute of Scientific and Technical Information of China (English)

    王伟; 纪志成

    2011-01-01

    The third-order nonlinear model of the PMSG-based wind power generation system (WECS) was established.In order to ensure maximum energy capture under rated wind speed, the nonlinear model was firsty linearized around different operating points, and the optimal tracking controller was designed for each operating point.And then a PMSG-based wind power generation control system was obtained using gain scheduling control with a stability preserving interpolation method.Simulation results indicate that the optimal tracking gain scheduling controller can effectively achieve maximum energy capture under rated wind speed.%在分析了 PMSG (永磁同步发电机)风力发电系统数学模型的基础上,以额定风速以下风能的最大捕获为目标,采用最优跟踪控制方法在系统不同工作点处设计了最优跟踪控制器,采用了一种能够保证稳定性的差值方法以插值增益调度的形式构成 PMSG 风力发电控制系统,并在 Matlab 中建立了 PMSG 风力发电控制系统的仿真模型.仿真结果表明,最优跟踪增益调度控制方法在额定风速以下能有效实现风力发电机组的最大风能捕获.

  19. Grape Seed Procyanidins and Cholestyramine Differentially Alter Bile Acid and Cholesterol Homeostatic Gene Expression in Mouse Intestine and Liver.

    Directory of Open Access Journals (Sweden)

    Rebecca M Heidker

    Full Text Available Bile acid (BA sequestrants, lipid-lowering agents, may be prescribed as a monotherapy or combination therapy to reduce the risk of coronary artery disease. Over 33% of adults in the United States use complementary and alternative medicine strategies, and we recently reported that grape seed procyanidin extract (GSPE reduces enterohepatic BA recirculation as a means to reduce serum triglyceride (TG levels. The current study was therefore designed to assess the effects on BA, cholesterol and TG homeostatic gene expression following co-administration with GSPE and the BA sequestrant, cholestyramine (CHY. Eight-week old male C57BL/6 mice were treated for 4 weeks with either a control or 2% CHY-supplemented diet, after which, they were administered vehicle or GSPE for 14 hours. Liver and intestines were harvested and gene expression was analyzed. BA, cholesterol, non-esterified fatty acid and TG levels were also analyzed in serum and feces. Results reveal that GSPE treatment alone, and co-administration with CHY, regulates BA, cholesterol and TG metabolism differently than CHY administration alone. Notably, GSPE decreased intestinal apical sodium-dependent bile acid transporter (Asbt gene expression, while CHY significantly induced expression. Administration with GSPE or CHY robustly induced hepatic BA biosynthetic gene expression, especially cholesterol 7α-hydroxylase (Cyp7a1, compared to control, while co-administration further enhanced expression. Treatment with CHY induced both intestinal and hepatic cholesterologenic gene expression, while co-administration with GSPE attenuated the CHY-induced increase in the liver but not intestine. CHY also induced hepatic lipogenic gene expression, which was attenuated by co-administration with GSPE. Consequently, a 25% decrease in serum TG levels was observed in the CHY+GSPE group, compared to the CHY group. Collectively, this study presents novel evidence demonstrating that GSPE provides additive and

  20. Metabolic and Homeostatic Changes in Seizures and Acquired Epilepsy-Mitochondria, Calcium Dynamics and Reactive Oxygen Species.

    Science.gov (United States)

    Kovac, Stjepana; Dinkova Kostova, Albena T; Herrmann, Alexander M; Melzer, Nico; Meuth, Sven G; Gorji, Ali

    2017-09-08

    Acquired epilepsies can arise as a consequence of brain injury and result in unprovoked seizures that emerge after a latent period of epileptogenesis. These epilepsies pose a major challenge to clinicians as they are present in the majority of patients seen in a common outpatient epilepsy clinic and are prone to pharmacoresistance, highlighting an unmet need for new treatment strategies. Metabolic and homeostatic changes are closely linked to seizures and epilepsy, although, surprisingly, no potential treatment targets to date have been translated into clinical practice. We summarize here the current knowledge about metabolic and homeostatic changes in seizures and acquired epilepsy, maintaining a particular focus on mitochondria, calcium dynamics, reactive oxygen species and key regulators of cellular metabolism such as the Nrf2 pathway. Finally, we highlight research gaps that will need to be addressed in the future which may help to translate these findings into clinical practice.

  1. Traditional Chinese medicine and the positive correlation with homeostatic evolution of human being: based on medical perspective.

    Science.gov (United States)

    Wang, Jie-Hua

    2012-08-01

    Adaptation is an eternal theme of biological evolution. The paper aims at exploring the conception of positive correlation between traditional Chinese medicine (TCM) and human homeostatic evolution based on medical perspective. Discussions mainly involve TCM conforming to natural laws and natural evolution of life, spontaneous harmonization of yin and yang and operating system of human self-healing, modern human immunology and human endogenous immune function in TCM, self-homeostasis of human micro-ecological state and balance mechanism on regulating base in TCM, as well as adaptation-eternal theme of biological evolution and safeguarding adaptability-value of TCM. In perspective of medicine, theory and practice of TCM are in positive correlation with human homeostatic evolution, and what TCM tries to maintain is human intrinsic adaptive capability to disease and nature. Therefore, it is the core value of TCM, which is to be further studied, explored, realized and known to the world.

  2. Fragile X protein FMRP is required for homeostatic plasticity and regulation of synaptic strength by retinoic acid.

    Science.gov (United States)

    Soden, Marta E; Chen, Lu

    2010-12-15

    Homeostatic synaptic plasticity adjusts the strength of synapses during global changes in neural activity, thereby stabilizing the overall activity of neural networks. Suppression of synaptic activity increases synaptic strength by inducing synthesis of retinoic acid (RA), which activates postsynaptic synthesis of AMPA-type glutamate receptors (AMPARs) in dendrites and promotes synaptic insertion of newly synthesized AMPARs. Here, we show that fragile X mental retardation protein (FMRP), an RNA-binding protein that regulates dendritic protein synthesis, is essential for increases in synaptic strength induced by RA or by blockade of neural activity in the mouse hippocampus. Although activity-dependent RA synthesis is maintained in Fmr1 knock-out neurons, RA-dependent dendritic translation of GluR1-type AMPA receptors is impaired. Intriguingly, FMRP is only required for the form of homeostatic plasticity that is dependent on both RA signaling and local protein synthesis. Postsynaptic expression of wild-type or mutant FMRP(I304N) in knock-out neurons reduced the total, surface, and synaptic levels of AMPARs, implying a role for FMRP in regulating AMPAR abundance. Expression of FMRP lacking the RGG box RNA-binding domain had no effect on AMPAR levels. Importantly, postsynaptic expression of wild-type FMRP, but not FMRP(I304N) or FMRPΔRGG, restored synaptic scaling when expressed in knock-out neurons. Together, these findings identify an unanticipated role for FMRP in regulating homeostatic synaptic plasticity downstream of RA. Our results raise the possibility that at least some of the symptoms of fragile X syndrome reflect impaired homeostatic plasticity and impaired RA signaling.

  3. Research data supporting "Emergence of homeostatic epithelial packing and stress dissipation through divisions oriented along the long cell axis"

    OpenAIRE

    Wyatt, Tom P. J.; Harris, Andrew R.; Lam, Maxine; CHENG*, Qian; Bellis, Julien; Dimitracopoulos, Andrea; Kabla, Alexandre J.; Charras, Guillaume T.; Baum, Buzz

    2015-01-01

    Data supporting publication 'Emergence of homeostatic epithelial packing and stress dissipation through divisions oriented along the cell long axis', PNAS. The tif files are image stacks. ImageJ (or Fiji) should be able to open them on any platform supporting the software. (http://imagej.nih.gov/ij/ or http://fiji.sc/Fiji ) "This work was supported by the Biotechnology and Biological Research Council [grant number BB/K013521], Engineering and Physical Research Council and the Wellcome Tr...

  4. A role for homeostatic drive in the perpetuation of complex chronic illness: Gulf War Illness and chronic fatigue syndrome.

    Directory of Open Access Journals (Sweden)

    Travis J A Craddock

    Full Text Available A key component in the body's stress response, the hypothalamic-pituitary-adrenal (HPA axis orchestrates changes across a broad range of major biological systems. Its dysfunction has been associated with numerous chronic diseases including Gulf War Illness (GWI and chronic fatigue syndrome (CFS. Though tightly coupled with other components of endocrine and immune function, few models of HPA function account for these interactions. Here we extend conventional models of HPA function by including feed-forward and feedback interaction with sex hormone regulation and immune response. We use this multi-axis model to explore the role of homeostatic regulation in perpetuating chronic conditions, specifically GWI and CFS. An important obstacle in building these models across regulatory systems remains the scarcity of detailed human in vivo kinetic data as its collection can present significant health risks to subjects. We circumvented this using a discrete logic representation based solely on literature of physiological and biochemical connectivity to provide a qualitative description of system behavior. This connectivity model linked molecular variables across the HPA axis, hypothalamic-pituitary-gonadal (HPG axis in men and women, as well as a simple immune network. Inclusion of these interactions produced multiple alternate homeostatic states and sexually dimorphic responses. Experimental data for endocrine-immune markers measured in male GWI subjects showed the greatest alignment with predictions of a naturally occurring alternate steady state presenting with hypercortisolism, low testosterone and a shift towards a Th1 immune response. In female CFS subjects, expression of these markers aligned with an alternate homeostatic state displaying hypocortisolism, high estradiol, and a shift towards an anti-inflammatory Th2 activation. These results support a role for homeostatic drive in perpetuating dysfunctional cortisol levels through persistent

  5. 连续搅拌反应釜过程的闭环增益成形PID控制器设计%PID controller design of closed-loop gain shaping in CSTR process

    Institute of Scientific and Technical Information of China (English)

    李述清; 张胜修; 张煜东; 胡波

    2011-01-01

    针对连续搅拌反应釜(CSTR)系统控制问题,设计了一种基于闭环增益成形算法的PID控制器,以提高PID控制器设计的简洁性和鲁棒性.首先假设期望闭环回路传递函数有一阶形式,同时将受控对象的一阶传递函数和PID控制器构成实际闭环回路传递函数.然后,比较期望闭环回路传递函数和实际闭环回路传递函数,即可确定PJD参数.最后,以某CSTR系统为例,利用该方法设计了PID控制器,并通过仿真结果比较,检验了该方法所得PID控制器的良好鲁棒稳定性和动态品质.%To solve the control problem of Continuous-Stirred-Tank-Reactor (CSTR), a straightforward PID design based on closed-loop gain shaping algorithm was proposed in this paper to enhance the simplicity and robustness of PID controller.Firstly, the transfer function of the anticipant closed-loop control system was assumed as a 1st order system, and the actual closed-loop transfer function was consisted of the 1 st order transfer function and PID controller.Then, the anticipated closedloop transfer function was compared with that of the actual closed-loop, thus the PID controller coefficients could be calculated.Finally, the robust PID controller was designed in a CSTR system.The simulation results demonstrate that the PID controller has better robust stability and dynamic performance.

  6. Homeostatic imbalance of purine catabolism in first-episode neuroleptic-naïve patients with schizophrenia.

    Science.gov (United States)

    Yao, Jeffrey K; Dougherty, George G; Reddy, Ravinder D; Keshavan, Matcheri S; Montrose, Debra M; Matson, Wayne R; McEvoy, Joseph; Kaddurah-Daouk, Rima

    2010-03-03

    Purine catabolism may be an unappreciated, but important component of the homeostatic response of mitochondria to oxidant stress. Accumulating evidence suggests a pivotal role of oxidative stress in schizophrenia pathology. Using high-pressure liquid chromatography coupled with a coulometric multi-electrode array system, we compared 6 purine metabolites simultaneously in plasma between first-episode neuroleptic-naïve patients with schizophrenia (FENNS, n = 25) and healthy controls (HC, n = 30), as well as between FENNS at baseline (BL) and 4 weeks (4w) after antipsychotic treatment. Significantly higher levels of xanthosine (Xant) and lower levels of guanine (G) were seen in both patient groups compared to HC subjects. Moreover, the ratios of G/guanosine (Gr), uric acid (UA)/Gr, and UA/Xant were significantly lower, whereas the ratio of Xant/G was significantly higher in FENNS-BL than in HC. Such changes remained in FENNS-4w with exception that the ratio of UA/Gr was normalized. All 3 groups had significant correlations between G and UA, and Xan and hypoxanthine (Hx). By contrast, correlations of UA with each of Xan and Hx, and the correlation of Xan with Gr were all quite significant for the HC but not for the FENNS. Finally, correlations of Gr with each of UA and G were significant for both HC and FENNS-BL but not for the FENNS-4w. During purine catabolism, both conversions of Gr to G and of Xant to Xan are reversible. Decreased ratios of product to precursor suggested a shift favorable to Xant production from Xan, resulting in decreased UA levels in the FENNS. Specifically, the reduced UA/Gr ratio was nearly normalized after 4 weeks of antipsychotic treatment. In addition, there are tightly correlated precursor and product relationships within purine pathways; although some of these correlations persist across disease or medication status, others appear to be lost among FENNS. Taken together, these results suggest that the potential for steady formation of

  7. Homeostatic modulation of stimulation-dependent plasticity in human motor cortex.

    Science.gov (United States)

    Ilić, N V; Milanović, S; Krstić, J; Bajec, D D; Grajić, M; Ilić, T V

    2011-01-01

    Since recently, it is possible, using noninvasive cortical stimulation, such as the protocol of paired associative stimulation (PAS), to induce the plastic changes in the motor cortex, in humans that mimic Hebb's model of learning. Application of TMS conjugated with peripheral electrical stimulation at strictly coherent temporal manner lead to convergence of inputs in the sensory-motor cortex, with the consequent synaptic potentiation or weakening, if applied repetitively. However, when optimal interstimulus interval (ISI) for induction of LTP-like effects is applied as a single pair, Motor evoked potential (MEP) amplitude inhibition is observed, the paradigm known as short-latency afferent inhibition (SLAI). Aiming to resolve this paradox, PAS protocols were applied, with 200 repetitions of TMS pulses paired with median nerve electrical stimulation, at ISI equal to individual latencies of evoked response of somatosensory cortex (N(20)) (PAS(LTP)), and at ISI of N(20) shortened for 5 msec (PAS(LTD)) - protocols that mimic LTP-like changes in the human motor cortex. MEP amplitudes before, during and after interventions were measured as an indicator based on output signals originating from the motor system. Post-intervention MEP amplitudes following the TMS protocols of PAS(LTP) and PAS(LTD) were facilitated and depressed, respectively, contrary to MEP amplitudes during intervention. During PAS(LTP) MEP amplitudes were significantly decreased in case of PAS(LTP), while in the case of PAS(LTD) an upward trend was observed. In conclusions, a possible explanation for the seemingly paradoxical effect of PAS can be found in the mechanism of homeostatic modulation of plasticity. Those findings indicate the existence of complex relationships in the development of plasticity induced by stimulation, depending on the level of the previous motor cortex excitability.

  8. Chemical control in steam systems by using a stabilized inorganic product with gain of energy and speed in detecting contaminations; Controle quimico em geradores de vapor, pelo uso de agente inorganico estabilizado, com ganhos de energia e celeridade na deteccao de contaminacoes

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Barny de; Pereira, Renato Andre Nunes [Kurita do Brasil, Rio de Janeiro, RJ (Brazil)

    2010-07-01

    This paper shows the basic conditions to control the relation between phosphate and sodium in high pressure boilers by applying a stabilized chemical product ensuring operation with low variability and energy gain by the eliminating of corrective blowdown. It presents the routine and the relevant benefits provided by a strong monitoring program of phosphate application in high pressure boilers as an important tool do detect deviations and to get better control of silica solubilization in this pressure level. (author)

  9. Climbing fiber signaling and cerebellar gain control

    NARCIS (Netherlands)

    G. Ohtsuki (Gen); C. Piochon (Claire); C.R.W. Hansel (Christian)

    2009-01-01

    textabstractThe physiology of climbing fiber signals in cerebellar Purkinje cells has been studied since the early days of electrophysiology. Both the climbing fiber-evoked complex spike and the role of climbing fiber activity in the induction of long-term depression (LTD) at parallel fiber-Purkinje

  10. Improved eating behaviours mediate weight gain prevention of young adults: moderation and mediation results of a randomised controlled trial of TXT2BFiT, mHealth program.

    Science.gov (United States)

    Partridge, Stephanie R; McGeechan, Kevin; Bauman, Adrian; Phongsavan, Philayrath; Allman-Farinelli, Margaret

    2016-04-02

    Explanatory evaluation of interventions for prevention of weight gain is required beyond changes in weight, to determine for whom the intervention works and the underlying mechanisms of change. It was hypothesised that participant characteristics moderate intervention effect on weight change and improved eating and physical activity behaviours during the 3-month program mediate the relationship between intervention and weight. In our randomised controlled trial, young adults at risk of weight gain (n = 250) were assigned either to an intervention group that received a 3-month mHealth (TXT2BFiT) program with 6-month maintenance or to a control group. Data were collected via online self-report surveys. Hypothesised moderators and mediators of the intervention effect on weight were independently assessed in PROCESS macro models for 3 and 9-month weight change. Males (P = 0.01), mid-20s age group (P = 0.04), and higher income earners (P = 0.02) moderated intervention effects on weight change at 3-months and males only at 9-months (P = 0.02). Weight change at 3 (-1.12 kg) and 9-months (-1.38 kg) remained significant when 3-month nutrition and physical activity behaviours were specified as mediators (P intervention group at 3-months accounted for 19 and 17% and decreased sugar-sweetened beverages accounted for 8 and 13% of indirect weight change effects at 3 and 9-months respectively. TXT2BFiT was effective for both young men and women. Small sustained behavioural changes, including increased vegetable intake and decreased sugar-sweetened beverages consumption significantly mediated the intervention's effects on weight change. Improved eating behaviours and increased physical activity accounted for approximately 40% of the weight change. The trial is registered with the Australian New Zealand Clinical Trials Registry ( ACTRN12612000924853 ).

  11. The V1 Population Gains Normalization

    NARCIS (Netherlands)

    Ganmor, Elad; Okun, Michael; Lampl, Ilan

    2009-01-01

    In this issue of Neuron, Busse et al. describe the population response to superimposed visual stimuli while Sit et al. examine the spatiotemporal evolution of cortical activation in response to small visual stimuli. Surprisingly, these two studies of V1 report that a single gain control model accoun

  12. Trial Protocol: Randomised controlled trial of the effects of very low calorie diet, modest dietary restriction, and sequential behavioural programme on hunger, urges to smoke, abstinence and weight gain in overweight smokers stopping smoking

    Directory of Open Access Journals (Sweden)

    Hajek Peter

    2010-10-01

    Full Text Available Abstract Background Weight gain accompanies smoking cessation, but dieting during quitting is controversial as hunger may increase urges to smoke. This is a feasibility trial for the investigation of a very low calorie diet (VLCD, individual modest energy restriction, and usual advice on hunger, ketosis, urges to smoke, abstinence and weight gain in overweight smokers trying to quit. Methods This is a 3 armed, unblinded, randomized controlled trial in overweight (BMI > 25 kg/m2, daily smokers (CO > 10 ppm; with at least 30 participants in each group. Each group receives identical behavioural support and NRT patches (25 mg(8 weeks,15 mg(2 weeks,10 mg(2 weeks. The VLCD group receive a 429-559 kcal/day liquid formula beginning 1 week before quitting and continuing for 4 weeks afterwards. The modest energy restricted group (termed individual dietary and activity planning(IDAP engage in goal-setting and receive an energy prescription based on individual basal metabolic rate(BMR aiming for daily reduction of 600 kcal. The control group receive usual dietary advice that accompanies smoking cessation i.e. avoiding feeling hungry but eating healthy snacks. After this, the VLCD participants receive IDAP to provide support for changing eating habits in the longer term; the IDAP group continues receiving this support. The control group receive IDAP 8 weeks after quitting. This allows us to compare IDAP following a successful quit attempt with dieting concurrently during quitting. It also aims to prevent attrition in the unblinded, control group by meeting their need for weight management. Follow-up occurs at 6 and 12 months. Outcome measures include participant acceptability, measured qualitatively by semi-structured interviewing and quantitatively by recruitment and attrition rates. Feasibility of running the trial within primary care is measured by interview and questionnaire of the treatment providers. Adherence to the VLCD is verified by the presence of

  13. Adaptive L-two-gain controller for flexible spacecraft attitude tracking%挠性卫星姿态跟踪自适应L2增益控制

    Institute of Scientific and Technical Information of China (English)

    肖冰; 胡庆雷; 马广富

    2011-01-01

    An adaptive L-two-gain controller is proposed for the attitude tracking of flexible spacecraft with external disturbances and input constraint.Neural networks are employed for the approximation of unknown system dynamics;an adaptive controller is developed to learn the undetermined parameters.Secondly, a robust controller is designed to achieve the L-two tracking performance with a desired disturbance-attenuation level.Finally, to treat the input constraint problem, the system is augmented with an auxiliary input signal error system.An improved adaptive L-two-gain controller is adopted to rapidly recover the unconstrained input signal when it goes beyond the input constraints.Simulations are carried out to study the effectiveness of the proposed control scheme; results show the theoretical and practical advantages of this approach.%针对在轨挠性卫星姿态跟踪时存在参数不确定、外部干扰以及控制输入受限等问题,提出了一种自适应L2增益控制方法.首先利用神经网络来逼近系统中的未知非线性动态特性,设计自适应控制律来处理系统中的不确定参数:其次设计了一鲁棒控制器使得干扰力矩对系统性能输出具有L2增益,从而实现对干扰的抑制控制.最后通过引入附加的输入误差系统,设计自适应L2增益控制器,使得当控制输入一旦超出幅值限制时能够立刻恢复到限制范围内,实现对输入受限问题的解决.仿真结果表明,该控制方法能够实现高精度的姿态跟踪控制,具有一定的可行性和有效性.

  14. 健康指导对血液透析患者控制体重增长过多的效果观察%Effect Observation of Health Guidance on Hemodialysis Patients Excessive Weight Gain Control

    Institute of Scientific and Technical Information of China (English)

    吕燕

    2014-01-01

    目的:运用健康教育使血液透析患者透析间期体重增长控制在干体重的5%以内。方法符合入选标准的60例患者随机分为实验组和对照组各30例,实验组给予针对性较强的健康教育加上常规护理,对照组则给予常规护理,并用调查问卷方式了解两组患者在透析间期体重控制的情况。结果实验组在透析间期体重控制在干体重的5%以内的也明显高于对照组(P<0.01)。结论对患者进行健康指导,提高透析质量,减少并发症的发生,从而提高患者的生活质量。%Objective to use the health education makes the blood dialysis interval weight gain control in dry weight within 5%. Methods 60 patients met the inclusion criteria were randomly divided into experimental group and control group with 30 cases in each group, the experimental group received targeted health education and routine nursing care, while the control group received routine nursing, and use the questionnaire to understand the two groups of patients in the interdialytic weight control. Results in the experimental group in the interdialytic weight control in dry weight within 5% were significantly higher than those in control group (P< 0.01). Conclusion health guidance for patients, improve the quality of dialysis, reduce complications, so as to improve the quality of life of the patients.

  15. Directionality switchable gain stabilized linear repeater

    Science.gov (United States)

    Ota, Takayuki; Ohmachi, Tadashi; Aida, Kazuo

    2004-10-01

    We propose a new approach to realize a bidirectional linear repeater suitable for future optical internet networks and fault location in repeater chain with OTDR. The proposed approach is the linear repeater of simple configuration whose directionality is rearranged dynamically by electrical control signal. The repeater is composed of a magneto-optical switch, a circulator, a dynamically gain stabilized unidirectional EDFA, and control circuits. The repeater directionality is rearranged as fast as 0.1ms by an electrical control pulse. It is experimentally confirmed that OTDR with the directionality switchable repeater is feasible for repeater chain. The detailed design and performance of the repeater are also discussed, including the multi-pass interference (MPI) which may arise in the proposed repeater, the effect of the MPI on SNR degradation of the repeater chain and the feed-forward EDFA gain control circuit.

  16. Multicriteria Gain Tuning for Rotorcraft Flight Controls (also entitled The Development of the Conduit Advanced Control System Design and Evaluation Interface with a Case Study Application Fly by Wire Helicopter Design)

    Science.gov (United States)

    Biezad, Daniel

    1997-01-01

    Handling qualities analysis and control law design would seem to be naturally complimenting components of aircraft flight control system design, however these two closely coupled disciplines are often not well integrated in practice. Handling qualities engineers and control system engineers may work in separate groups within an aircraft company. Flight control system engineers and handling quality specialists may come from different backgrounds and schooling and are often not aware of the other group's research. Thus while the handling qualities specifications represent desired aircraft response characteristics, these are rarely incorporated directly in the control system design process. Instead modem control system design techniques are based on servo-loop robustness specifications, and simple representations of the desired control response. Comprehensive handling qualities analysis is often left until the end of the design cycle and performed as a check of the completed design for satisfactory performance. This can lead to costly redesign or less than satisfactory aircraft handling qualities when the flight testing phase is reached. The desire to integrate the fields of handling qualities and flight,control systems led to the development of the CONDUIT system. This tool facilitates control system designs that achieve desired handling quality requirements and servo-loop specifications in a single design process. With CONDUIT, the control system engineer is now able to directly design and control systems to meet the complete handling specifications. CONDUIT allows the designer to retain a preferred control law structure, but then tunes the system parameters to meet the handling quality requirements.

  17. Intrinsic gain modulation and adaptive neural coding

    CERN Document Server

    Hong, Sungho; Fairhall, Adrienne

    2008-01-01

    In many cases, the computation of a neural system can be reduced to a receptive field, or a set of linear filters, and a thresholding function, or gain curve, which determines the firing probability; this is known as a linear/nonlinear model. In some forms of sensory adaptation, these linear filters and gain curve adjust very rapidly to changes in the variance of a randomly varying driving input. An apparently similar but previously unrelated issue is the observation of gain control by background noise in cortical neurons: the slope of the firing rate vs current (f-I) curve changes with the variance of background random input. Here, we show a direct correspondence between these two observations by relating variance-dependent changes in the gain of f-I curves to characteristics of the changing empirical linear/nonlinear model obtained by sampling. In the case that the underlying system is fixed, we derive relationships relating the change of the gain with respect to both mean and variance with the receptive fi...

  18. Diversity Gain through Antenna Blocking

    Directory of Open Access Journals (Sweden)

    V. Dehghanian

    2012-01-01

    Full Text Available As part of the typical usage mode, interaction between a handheld receiver antenna and the operator's RF absorbing body and nearby objects is known to generate variability in antenna radiation characteristics through blocking and pattern changes. It is counterintuitive that random variations in blocking can result in diversity gain of practical applicability. This diversity gain is quantified from a theoretical and experimental perspective. Measurements carried out at 1947.5 MHz verify the theoretical predictions, and a diversity gain of 3.1 dB was measured through antenna blocking and based on the utilized measurement setup. The diversity gain can be exploited to enhance signal detectability of handheld receivers based on a single antenna in indoor multipath environments.

  19. Developmental gains in visuospatial memory predict gains in mathematics achievement.

    Science.gov (United States)

    Li, Yaoran; Geary, David C

    2013-01-01

    Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.

  20. Developmental gains in visuospatial memory predict gains in mathematics achievement.

    Directory of Open Access Journals (Sweden)

    Yaoran Li

    Full Text Available Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4 were larger than gains in the capacity of the central executive (d = 1.6 that in turn were larger than gains in phonological memory span (d = 1.1. First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.